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Altitudinal migration as a factor in the nutrition of bighorn sheep Hebert, Daryll Marvin 1973

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c ALTITUDINAL MIGRATION AS A FACTOR IN THE NUTRITION OF BIGHORN SHEEP by DARYLL MARVIN HEBERT B.Sc, University of British Columbia, 1965 M.Sc, University of British Columbia, 1967 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in the Department of ZOOLOGY We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA 1973 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the Head of my Department or by his representatives. It i s understood that copying or publication of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. n i i o Zoology Department of The University of B r i t i s h Columbia Vancouver 8, Canada September 20th, 1973 i i . ABSTRACT A l t i t u d i n a l migration i s a feature common to most wild ungulates along the Rocky Mountain chain. This study, conducted from 1968-70 i n the East Kootenay region of B r i t i s h Columbia, used bighorn sheep as the experimental animal and undertook to examine various n u t r i t i o n a l parameters which might benefit populations of migratory animals. Basic range studies were conducted to complement extensive measurements of the n u t r i t i o n a l status of the various groups of captive sheep. Quantitative measurements were made of the species composition of several winter ranges and approximate composition of the winter and summer range diets along with phenology and forage moisture i n order to assess a v a i l a b i l i t y , p a l a t a b i l i t y and s u i t a b i l i t y for maintenance of wintering animals. Between year differences were found to influence a v a i l a b i l i t y of spring growth, nutrient intake and apparent d i g e s t i b i l i t y . Q u a l i t a t i v e measurements were conducted approximately monthly to determine crude protein, gross energy and phosphorus content of the winter and summer range forage. Animal t r i a l s were conducted over a two year period using two methods of d i e t simulation. During 1968-69, a i i i . s i ngle group of adult sheep was given forages varying i n q u a l i t y (crude protein) to represent the natural sequence of events on the range from early spring u n t i l l a t e winter. Two groups of y e a r l i n g sheep were used during the second year. One group, representing the c o n t r o l , was maintained on forage from the winter range year around. The other was given spring growth winter range forage, then changed to alpine range forage and f i n a l l y returned to winter range forage during the l a t e f a l l and winter period i n order to simulate the normal migratory pattern. The response of each group was measured through change i n body weight. The summer range forage was assessed f o r i t s a b i l i t y to supply nutrients i n the feed, i t s e f f e c t on feed intake and d i g e s t i b i l i t y and i t s influence on d i g e s t i b l e nutrients and nitrogen retained. I t proved superior to the corresponding winter range forage f o r a l l methods of evalu-ation. The improved q u a l i t y alpine forage given to the migratory group also found expression the following spring through better u t i l i z a t i o n of l a t e winter forage and early spring growth. A series of p r e d i c t i v e l i n e a r equations was estab-l i s h e d for each forage type i n order to estimate such things as crude protein from forage moisture, feed intake and d i g e s t i b i l i t y from nutrient content of the forage and feed i v . and nutrient intake using f e c a l nitrogen techniques. They served to demonstrate differences i n e f f i c i e n c y of forage u t i l i z a t i o n , between groups, and allowed a quantitative assessment of the e f f e c t of changes i n forage q u a l i t y on feed and nutrient intake. The c o l l e c t i o n of basic range data along with the animal t r i a l s allowed an estimation of the d i g e s t i b l e energy required for body maintenance, c a l c u l a t i o n of the yearly intake of nutrients and feed and i n s i g h t into nitrogen as the l i m i t i n g nutrient during the c r i t i c a l winter period. I t was found that minimum ambient temperature during the c r i t i c a l winter period increased feed intake even though forage q u a l i t y appeared to r e s t r i c t the amount of feed ingested. Also, examination of f e c a l and urinary pathways of protein loss indicated that the kidney was regulating nitrogen loss v i a the urine during periods of nitrogen shortage. C o l l e c t i o n of data of t h i s type provides opportuni-t i e s for future experimentation inv o l v i n g manipulation of •dietary composition, forage q u a l i t y and the establishment of p r e d i c t i v e equations and maintenance values by season. I t w i l l lead to a better understanding of carrying capacity through the comparison of feed and nutrient intake of several species on a single range, on a metabolic weight basis. V . TABLE OF CONTENTS Page ABSTRACT i i . TABLE OF CONTENTS V . LIST OF TABLES i x . LIST OF FIGURES xiv. ACKNOWLEDGMENTS xxv. INTRODUCTION 1 DESCRIPTION OF THE STUDY AREA 4 METHODS AND MATERIALS 6 ANIMAL METHODS 6 Experimental animals 6 Body weight change 6 Digestion t r i a l pens 7 Digestion t r i a l s 8 Scouring 8 PLANT METHODS 9 Diets 9 C o l l e c t i o n of forage 10 Simulation of natural d i e t s 10 Analysis of samples . 12 Range studies 13 RESULTS 15 CLIMATIC AND FORAGE DIFFERENCES BETWEEN YEARS . . 15 RANGE STUDIES . 23 v i Page Forage moisture . . 23 Phenology •. 32 Species composition of three winter ranges 39 SELECTION BETWEEN FORAGES UNDER CONTROLLED CONDITIONS 42 SPECIES COMPOSITION OF NATURAL AND PEN FED DIETS 45 CHANGE IN PLANT NUTRIENTS DURING 1968 53 SEASONAL TRENDS IN PLANT NUTRIENTS 58 Crude protein 58 Gross energy 66 The r e l a t i o n s h i p between crude protein and gross energy 72 Seasonal changes i n forage phosphorus 75 ANIMAL TRIALS .. 79 Introduction 79 Period of adjustment to the experimental d i e t s . 81 Apparent d i g e s t i b i l i t y of dry matter 8 4 Voluntary feed intake . 88 Ingested protein 9 3 Apparent d i g e s t i b l e protein 96 Nitrogen balance 10 0 Ingested energy 106 Apparent d i g e s t i b l e energy 109 The r a t i o of d i g e s t i b l e protein to d i g e s t i b l e energy 113 Fecal weights and protein loss 118 Changes i n urine volume and protein content of the urine 12 4 v i i Page A comparison of protein loss by the f e c a l and urinary pathways 131 Fecal energy losses I36 Feed intake r e l a t i o n s h i p s 138 Estimation of the l i m i t i n g nutrient 139 SIMULATED ALTITUDINAL MIGRATION 142 Sequence of feeding 142 Actual and calculated body weights 142 Apparent d i g e s t i b i l i t y 146 Voluntary feed intake •••• 149. Feed intake and apparent d i g e s t i b i l i t y 151 Feed intake - D i g e s t i b i l i t y changes and the e f f e c t on nutrient intake 162 Feed intake and nutrient content of the forage ... 166 Feed intake and ambient temperature 17 5 Ingested protein 183 Apparent digestible- : protein 189 Nitrogen balance studies 202 Ingested energy 212 Apparent d i g e s t i b l e energy 223 The d i g e s t i b l e protein to energy r a t i o 229 The f e c a l pathway ................................. 235 Absolute protein i n the urine i n r e l a t i o n to urine volume 24 4 A comparison of f e c a l and urinary protein loss .... 248 Voluntary water intake 2 52 AN ESTIMATION OF ENERGY FOR BODY MAITENANCE 263 v i i i Page A COMPARISON OF THE CONTROL AND EXPERIMENTAL GROUPS ON A HIGH QUALITY RATION AFTER BEING ON " SUB MAINTENANCE RATIONS 268 FEED AND NUTRIENT INTAKE PER YEAR 273 DISCUSSION AND CONCLUSIONS 282 SUMMARY 306 LITERATURE CITED 316 APPENDICES 325 A. SCIENTIFIC AND COMMON NAMES FOR PLANT SPECIES CITED 325 B. SPECIES COMPOSITION OF TWO WINTER RANGES IN THE EAST KOOTENAY 328' C. SPECIES COMPOSITION OF THE NATURAL DIETS FED DURING 1968-1969 331 D. PLANT NUTRIENT RELATIONSHIPS 333 E. ESTIMATION OF THE PERIOD OF ADJUSTMENT TO THE EXPERIMENTAL DIETS 343 F. THE APPROXIMATE COMPOSITION OF RATION 36-57..346 G. PLANT NUTRIENT-FEED INTAKE RELATIONSHIPS ... 3 48 H . A MEASURMENT OF FORAGE QUALITY, INTAKE, ANIMAL PERFORMANCE AND URINARY AND FECAL LOSSES FOR AN IMPROVED DIET 35 2 I. ENERGY METABOLISM 355 ix LIST OF TABLES Table Page 1. Monthly and yearly p r e c i p i t a t i o n records from the Cranbrook a i r p o r t for the three growing years studied 16 2. The proportion of the previous year's forage to the current year's growth, using blue-bunch wheatgrass as the indicator species (percentages based upon f i e l d dried weights) 17 3. A comparison of crude protein and gross energy values, for s i m i l a r dates, for d i e t s approximately s i m i l a r i n species composition and phenology 20 4. A comparison of d i g e s t i b i l i t y between years (1968 and 1969) on forages approximately s i m i l a r i n species composition and phenology 21 5. Forage moisture content of two winter range. grass mixtures showing v a r i a t i o n due to composition, l o c a t i o n and season, 1968 . . . 24 6. Forage moisture content of winter range grass mixtures showing seasonal v a r i a t i o n , 1969 25 7. Forage moisture content of subalpine and alpine mixtures, c o l l e c t e d during 1968 and 1969 . . 26 8. The timing of the phenological stages of winter range forages for three winter ranges, during 1968 . 33 9. The timing of phenological stages of forage from various s i t e s on the Premier Ridge winter range, 1969 34 10. A comparison of phenological stages of rough fescue on the E s t e l l a winter range, i n r e l a t i o n to elevation, 1969 35 11. The timing of phenological growth stages of sub-alpine and alpine forage, 1968 36 12. The timing of phenological growth stages of sub-alpine and alpine forage, 1969 38 X Table Page 13. The percent canopy coverage and frequency of occurrence for the Douglas f i r - bunchgrass vegetation type of the East side of Premier Ridge . . . 4 0 14. The percent canopy coverage and frequency of occurrence for the Agropyron-Purshia community of the B u l l River area and for the Wigwam winter range 41 15. The percent canopy coverage and frequency of occurrence for two s i t e s i n the Agropyron-Purshia community of the B u l l River area, on steep slopes where no domestic grazing occurs. 333 16. The percent canopy coverage and frequency of occurrence for three s i t e s on the Wigwam winter ranges 334 17. F i e l d s e l e c t i v i t y t r i a l s using an imprinted bighorn sheep, showing a comparison between Premier Ridge winter range and two summer ranges 44 18. A comparison of s e l e c t i o n under c o n t r o l l e d conditions between winter and summer range forages 46 19. A de s c r i p t i o n of the composition of the d i e t s fed to the adult ewe group during 1968-69 . . 48 20. A d e s c r i p t i o n of the composition of the winter range d i e t s fed to the control group during 1969-70 and to the experimental group ( A p r i l -July and October to March) 49 21. The composition of the summer range d i e t s fed to the experimental group during 1969 . . . . 51 .22. Crude protein and gross energy values with and without the energy contributed by the crude protein f r a c t i o n , i n winter and summer range forage cut i n 1968 54 23. The yearly change i n crude protein and gross energy with and without the energy contribu-t i o n of the protein f r a c t i o n i n winter and summer range plants, 1969-70 59 24. The seasonal changes i n the crude protein to gross energy r a t i o for winter and summer range forages, 1969-70 7 4 \ x i Table Page 25. The seasonal changes i n the phosphorus content of winter and summer range forages, 1969-70. 76 26. The decline i n protein intake and d i g e s t i b l e protein with changes i n d i e t 89 27. The r a t i o of ingested protein to crude protein content of the forage, 1968-69 . 95 28. The r a t i o of d i g e s t i b l e protein to crude protein content of the forage 99 29. A summary of nitrogen and protein balance as i t r e l a t e s to season and di e t a r y q u a l i t y expressed as percent crude protein, for the adult ewe group, 1968-69 i.02 30. Nitrogen retained per gram of ingested nitrogen, per kilogram of body weight and per kilogram of body weight*75 i n r e l a t i o n to changes i n die t a r y q u a l i t y for the adult ewe group . . . 105 31. The r a t i o of ingested energy to gross energy of the forage during 1968-69 108 32. The r a t i o of d i g e s t i b l e energy to gross energy content of the forage 112 33. The r a t i o of d i g e s t i b l e protein to d i g e s t i b l e energy for the adult ewe group while on d i e t s changing i n nutrient content 115 34. A summary of f e c a l loss and f e c a l protein f o r the adult ewe group, 1968-69 119 35. The change i n urine volume and loss of protein i n the uring during 1968-69, while on forage d e c l i n i n g i n q u a l i t y 125 36. A comparison of .protein loss by the f e c a l and urinary pathways i n r e l a t i o n to d e c l i n i n g dietary q u a l i t y during 1968-69, as shown by ingested protein 132 37. The actual and estimated d i g e s t i b l e protein i n r e l a t i o n to the d i g e s t i b l e energy intake while " the adult ewe group was on natural forages, 1968-69 140 38. The average feed intake per day for the control and experimental groups while on forage cut during 1969-70 150 x i i Table Page 39. The change i n d i g e s t i b i l i t y for i n d i v i d u a l s of the adult and yearling groups as affected by l e v e l of feeding . . J . . . 16 3; 40. The change i n d i g e s t i b i l i t y for the adult and ye a r l i n g animals as a u n i t , i n r e l a t i o n to l e v e l of feeding and q u a l i t y of the d i e t . . 165 41. The apparent d i g e s t i b l e protein intake and percent d i g e s t i b l e protein for the control and experimental group of sheep 190 42. The apparent d i g e s t i b l e protein intake per kilogram body weight for the c o n t r o l and experimental groups of sheep 194 43. A summary of nitrogen balance from the c o n t r o l and experimental groups, with the associated protein balance, during 1969-70 203 44. Nitrogen retained per gram of ingested protein, per kilogram of body v/eight and per kilogram of body weight*75 for the control group, during 1969-70 2 06 45. Nitrogen retained per gram of ingested protein, per kilogram of body weight and per kilogram of body w e i g h t * f o r the experimental group, during 1969-70 . 2 07 46. The d i g e s t i b l e protein to energy r a t i o for the control and experimental groups during 1969-70. 23 0 47. The change i n e f f i c i e n c y of nitrogen conversion among seasons for the control and experimental 25 5 group 48. A summary of comparative water intake between the control and experimental groups for each period. . . . ' 26 3 49. The approximate composition of r a t i o n 36-57 . . 3 47 50. A comparison of the n u t r i t i o n a l parameters between the control and experimental group .while on r a t i o n 36-57, a f t e r being on sub-maintenance rations 270 51. A comparison of the control and experimental groups on r a t i o n 36-57, with each n u t r i t i o n a l category expressed i n terms of body weight and body weight*75 f a f t e r being on sub-maintenance rations 272 x i i i Table Page 52. A comparison of annual feed and nutrient intake between the control and experimental group, during 1969-70 275 53. The percentage increase i n feed and nutrient intake by the experimental over the con t r o l group, based on yearly t o t a l s 276 54. The annual nutrient intake of the experimental group showing the contribution of the summer range forage between periods on winter range forage 279 55. The annual nutrient intake of the experimental group expressed i n terms of body weight, show-ing the contribution of the summer range forage between periods on winter range forage 2 8 0 56. The annual nutrient intake of the experimental group expressed i n terms of metabolic body weight showing the contribution of the summer range forage between periods on winter range forage . . . . . . . . 281 57. A summary of forage q u a l i t y , intake and animal performance when the adult ewe group was placed on an improved d i e t during the l a t e winter of 1968-69 353 58. A summary of urinary and f e c a l losses as protein and energy when the adult ewe group was placed on an improved d i e t during the la t e winter of 1968-69 354 x i v LIST OF FIGURES Figure Page 1. The r e l a t i o n between forage moisture content of winter and summer range forages, showing seasonal v a r i a t i o n . . . ^9 2. The r e l a t i o n s h i p between forage moisture and crude protein content of winter range forages, 1969 , • 30 3. The r e l a t i o n s h i p between forage moisture and crude protein content of subalpine and alpine range plants, 1969 30 4. The r e l a t i o n s h i p between forage moisture and crude protein content of winter and summer range plants, 1969 . . .. 31 5. The r e l a t i o n s h i p between crude protein and gross energy content for the d i e t s fed to the adult ewe group when the gross energy deter-mination includes that of the crude protein contribution 57 6. The r e l a t i o n s h i p between crude protein and gross energy content for the d i e t s fed to the adult ewe group when the gross energy determination does not include that of the crude protein contribution . . . . . 57 7. The seasonal changes i n crude protein i n winter range plants fed to captive sheep, 1969-70 . . gQ "8. The seasonal changes i n crude protein i n summer range plants fed to captive sheep, 1969-70. 55 9. The seasonal changes i n gross energy values of winter range plants, 1969-70, with and without the energy contribution made by the crude protein f r a c t i o n 68 10. The seasonal changes i n gross energy values of summer range plants, 1969-70, with and with-out the energy contribution made by the crude protein f r a c t i o n . . 69 XV Figure Page 11. The r e l a t i o n s h i p between the crude protein and gross energy content of winter range forage, when the energy contribution of the crude protein f r a c t i o n has not been separated . . . . 340 12. The r e l a t i o n s h i p between the crude protein and gross energy content of winter range forage when the energy contribution of the crude protein has been separated . 340 13. The r e l a t i o n s h i p between crude protein and gross energy for winter and summer range forage cut during 1969-70 for the experimental group. X = Premigratory, Y = Migratory, Z = Postmigratory 341 14. The r e l a t i o n s h i p between crude protein and gross energy for winter and summer range forage given to the experimental group, without the removal of the energy contribution of the crude protein f r a c t i o n 34 2 15. The r e l a t i o n s h i p between the crude protein and gross energy content of winter and summer range forage when the energy contribution of the crude protein has been removed . . . . . . . . 342 16. The annual cycle of t o t a l phosphorus i n winter and summer range plants, 1969-70 78 17. The average d a i l y voluntary feed intake of alpine forage for three adult ewes, using two day averages 83 18. The average d a i l y voluntary feed intake of winter range grass cut June 6 for three adult ewes, using two day averages 344 19. The average d a i l y voluntary feed intake of winter range grass cut July 24 for three adult ewes, using two day averages 34 5 20. The change i n average apparent d i g e s t i b i l i t y for three adult ewes i n r e l a t i o n to protein content of the d i e t 8 5 21. The r e l a t i o n s h i p between crude protein content of the forage and the apparent d i g e s t i b i l i t y of dry matter for the d i e t s fed the adult ewe group . 87 x v i Figure Page 22. The average feed intake for three adult ewes while on d i e t s cut during the summer of 1968 90 23. The r e l a t i o n s h i p between feed intake and apparent d i g e s t i b i l i t y for the adult ewe group . 9 2 24. The absolute protein intake for three adult ewes while on forage cut during the summer of 1968 94 25. The change i n apparent d i g e s t i b l e protein for the adult ewe group, with seasonally d e c l i n i n g dietary q u a l i t y 9 7 26. Changes i n nitrogen retained i n r e l a t i o n to dietary q u a l i t y , for the adult ewes, 1968-69 . . 3_03 27. The average d a i l y absolute energy intake for three adult ewes during 1968-69 1 ° 7 28. The change i n d i g e s t i b l e energy intake for three adult ewes with seasonally changing dietary q u a l i t y expressed as gross energy. 110 29. The r e l a t i o n s h i p between the d i g e s t i b l e protein to energy r a t i o and the crude protein to gross energy r a t i o during 196 8-69 . H7 30. The change i n f e c a l weight i n r e l a t i o n to changes i n apparent d i g e s t i b i l i t y of the d i e t , arranged i n seasonal sequence for the adult ewe group 120 31. The r e l a t i o n s h i p between apparent d i g e s t i b i l i t y and weight of feces per day for the adult ewe group, 1968-69 121 32. The quantity of protein l o s t i n the feces i n grams and as a percentage of ingested protein for the adult ewes, 1968-69 122 33. The change i n urine volume during the f a l l and winter of 1968-69, while on d i e t s d e c l i n i n g i n q u a l i t y 327 34. The r e l a t i o n s h i p between urine volume and water intake during 1968-69 . 128 x v i i Figure Page 35. The change i n average percent protein and t o t a l protein i n the urine for three adult ewes i n r e l a t i o n to changes i n d i e t , 1968-69 129 36. Absolute protein losses i n r e l a t i o n to ingested protein and crude protein content of the d i e t during 1968-69, arranged i n seasonal, sequence . 133 37. Protein l o s t i n the feces and urine as a per-cent of ingested protein and urinary protein as a percent of d i g e s t i b l e protein for the adult ewe group during 1968-69 135 38. The change i n f e c a l energy associated with d e c l i n i n g energy intake for the adult ewes during 1968-69, arranged i n seasonal sequence . 137 39. The r e l a t i o n s h i p between average feed intake and percent protein i n the feed 349 40. The r e l a t i o n s h i p between average feed intake and d i g e s t i b l e protein 349 41. The r e l a t i o n s h i p between feed intake and gross energy i n the feed 35O 42. The re l a t i o n s h i p between average feed intake and ingested energy 350 43. The re l a t i o n s h i p between feed intake and apparent d i g e s t i b l e energy 35I 44. The re l a t i o n s h i p between feed intake and the di g e s t i b l e protein to energy r a t i o 351 45. A comparison of the calculated weight and actual body weight change for the con t r o l group 14 3 46. A comparison of the calculated weight and actual body weight change for the experimental group 144 47. A de s c r i p t i o n of the seasonal changes i n apparent d i g e s t i b i l i t y of dry matter and a comparison of d i g e s t i b i l i t y between the con t r o l and experimental groups 148 48. A comparison of average d a i l y feed intake be-tween a migratory and non-migratory group of year l i n g sheep 151 x v i i i Figure Page 49. A comparison of average feed intake/kilogram body weight for a migratory and non-migratory group of yearling sheep 152 50. The r e l a t i o n s h i p between feed intake and apparent d i g e s t i b i l i t y of dry matter for both groups of sheep under the influence of dietary q u a l i t y (CP) and body weight change 157 51. The r e l a t i o n s h i p between the apparent digest-i b i l i t y of dry matter and d a i l y feed intake for the experimental group on winter and summer range forage (average values) 158 52. The re l a t i o n s h i p between the apparent digest- v: . i b i l i t y of dry matter and feed intake/kilogram body weight for the control group (average values) 159 53. The r e l a t i o n s h i p between the apparent digest-i b i l i t y of dry matter and feed intake/kilogram body weight for the experimental group (average values) 159 54. The r e l a t i o n s h i p between feed intake/kilogram body weight and apparent d i g e s t i b i l i t y of dry matter under the common influence of dietary q u a l i t y 160 55. The r e l a t i o n s h i p between feed intake and body weight change for both groups of sheep 167 56. The re l a t i o n s h i p between crude protein content of the d i e t and d a i l y feed intake for the control group 169 57. The r e l a t i o n s h i p between crude protein content of the d i e t and d a i l y feed intake/kilogram body weight for the control group . . . . . 171 58. The re l a t i o n s h i p between crude protein content of the feed and d a i l y feed intake for the experi-mental group 173 59. The re l a t i o n s h i p between crude protein content of the d i e t and feed intake/kilogram body weight for the experimental group . . . . . 173 60. The r e l a t i o n s h i p between gross energy content of the d i e t and feed intake/kilogram body weight for the experimental group 174 xix Figure Page 61. Average d a i l y feed intake/kilogram body weight for the control and experimental groups of sheep i n r e l a t i o n to changes i n ambient temperature. I ? 7 62. The r e l a t i o n s h i p between minimum ambient temp-erature and feed intake/kilogram body weight for the control group l 7 ^ 63. The r e l a t i o n s h i p between minimum ambient temp-erature and feed intake/kilogram body weight for the experimental group I 7 8 64. Changes i n minimum ambient temperature and d a i l y feed intake for the adult ewe group during November 1968 . . . . . . 1 7 9 65. Changes i n minimum ambient temperature and feed intake for the adult ewe group during February and January 1969 1 8 1 66. The r e l a t i o n s h i p between minimum ambient temp--erature and d a i l y feed intake for the adult ewe group. 67. The absolute protein intake for the migratory and non-migratory groups of sheep while on forage cut during 1969-70 i 8 4 68. The r e l a t i o n s h i p between body weight and the quantity of protein ingested shown as average values, for both groups of sheep I 8 7 69. The r e l a t i o n s h i p between crude protein content of the winter range feed and ingested protein, for the control group I 8 8 70. The r e l a t i o n s h i p between crude protein content of the winter and summer range forage and ingested protein, for the experimental group I 8 8 71. The change i n apparent d i g e s t i b l e protein intake for the control and experimental groups of sheep 1 9 1 72. The change in apparent d i g e s t i b l e protein intake/ kilogram body weight for the control and experi-mental groups of sheep I 9 2 73. The r e l a t i o n s h i p between body weight and absolute d i g e s t i b l e protein intake for both groups of sheep l 9 ^ XX Figure Page 74. The r e l a t i o n s h i p between the crude protein content of winter range forage and the apparent d i g e s t i b l e protein intake for the control group 197 75. The r e l a t i o n s h i p between the crude protein content of v/inter range forage and percent d i g e s t i b l e protein for the control group . . . 197 76. The r e l a t i o n s h i p between the crude protein content of the v/inter and summer range forage and the apparent d i g e s t i b l e protein intake for the experimental group . 198 77. The r e l a t i o n s h i p between the crude protein content of winter and summer range forage and percent d i g e s t i b l e protein for the experi-mental group 198 78. The r e l a t i o n s h i p between the crude protein content of winter range forage and d i g e s t i b l e protein intake/kilogram body weight for the control group 200 79. The r e l a t i o n s h i p between the crude protein content of winter and summer range forage and d i g e s t i b l e protein intake/kilogram body weight for the experimental group 20 0 80. The re l a t i o n s h i p between the apparent digest-i b i l i t y of dry matter and percent apparent d i g e s t i b l e protein for the control group . . . 201 81. The r e l a t i o n s h i p between the apparent digest-i b i l i t y of dry matter and percent apparent d i g e s t i b l e protein for the experimental group 201 82. A comparison of nitrogen retention between the control and experimental groups during 1969-70. 204 83. The r e l a t i o n s h i p between crude protein content of the winter and summer range forage and nitrogen retained/kilogram of nitrogen ingested for the experimental group 2 09 84. The r e l a t i o n s h i p between ingested protein and nitrogen retained/kilogram body weight for the control group . 210 85. The r e l a t i o n s h i p between ingested protein and nitrogen retained/kilogram body weight for the experimental group 21 0 xx i Figure Page 86. The re l a t i o n s h i p between d i g e s t i b l e p r o t e i n / kilogram body weight and nitrogen retained/ • ? n kilogram body weight for the control group* -87. The re l a t i o n s h i p between d i g e s t i b l e p r o t e i n / kilogram body weight and nitrogen retained/ kilogram body weight for the experimental group 211 88. Seasonal changes i n average absolute energy intake for the control and experimental groups of sheep during 1969-70 213 89. Seasonal changes i n the ingested energy intake/ kilogram body weight for the control and experimental groups . . . . . . . . .. . . 214 90. The re l a t i o n s h i p between body weight and ingested energy for the control and • experimental groups of sheep . . . . . . . 215 91. The re l a t i o n s h i p between gross energy content of the winter and summer range forage and ingested energy for the experimental group . . 3 56 92. The re l a t i o n s h i p between gross energy content of the winter and summer range forage and energy intake/kilogram body weight for the experi-mental group 3 56 93. A comparison of the seasonal changes of apparent d i g e s t i b l e energy for the control and experi-mental groups . . . . . . . . . . 218 94. A comparison of the seasonal changes i n percent d i g e s t i b l e energy between the control and experimental groups . . . 220 95. A comparison of the d i g e s t i b l e energy intake/ kilogram body weight between the control and experimental groups, during 1969-70 221 96. A comparison of the d i g e s t i b l e energy intake/ gram of feed intake r a t i o between the control and experimental groups during 1969-70. 223 97. The re l a t i o n s h i p between body weights and the di g e s t i b l e energy intake for in d i v i d u a l s of the control and experimental groups of yea r l i n g sheep 22 5 x x i i Figure Page 98. The r e l a t i o n s h i p between the gross energy content of winter range forage and the digest-i b l e energy intake/kilogram body weight for' 2 26 the control group 99. The r e l a t i o n s h i p between the gross energy content of the winter and summer range forage and the d i g e s t i b l e energy intake/kilogram body weight for the experimental group . . . . 226 100. The r e l a t i o n s h i p between the ingested energy content of winter range forage and digest-i b l e energy intake/kilogram body weight for the control group 2 27 101. The r e l a t i o n s h i p between the ingested energy content of winter and summer range forage and the d i g e s t i b l e energy intake/kilogram body weight for the experimental group 2 27 102. The re l a t i o n s h i p between the percent digest-i b l e energy and the apparent d i g e s t i b i l i t y of dry matter for the control group . . . . . . . 228 103. The r e l a t i o n s h i p between the percent digest-i b l e energy and the apparent d i g e s t i b i l i t y of dry matter for the experimental group . . . . 2 28 104. The re l a t i o n s h i p between the crude protein to gross energy r a t i o and the d i g e s t i b l e protein to energy r a t i o f or the control group . . . . 23 3 105. The r e l a t i o n s h i p between the crude protein to gross energy r a t i o and the d i g e s t i b l e protein to energy r a t i o for the experimental group . . 23 3 106. The pre d i c t i o n of the d i g e s t i b l e protein to energy r a t i o from the crude protein content of winter range forage fed to the control group 23 4 107. The pr e d i c t i o n of the d i g e s t i b l e protein to energy r a t i o from the crude protein content of winter and summer range forage fed to the experimental group . . . . . . . . . . . . . . 23 4 108. A comparison of absolute f e c a l loss for the control and experimental groups . . . . . . . 236 109. The change i n f e c a l loss (gm/day)/gram of feed intake per day for the control and experimental groups . . . . . . . . . 2 37 x x i i i F i g u r e Page 110. The change i n crud e p r o t e i n c o n t e n t o f t h e f e c e s f o r t h e c o n t r o l and e x p e r i m e n t a l groups o f sheep 2 39 111. The p r e d i c t i o n o f crud e p r o t e i n c o n t e n t o f t h e f e e d from f e c a l p r o t e i n c o n t e n t , f o r t h e c o n t r o l group 24 0 112. The p r e d i c t i o n o f crud e p r o t e i n c o n t e n t o f t h e f e e d from f e c a l p r o t e i n c o n t e n t , f o r t h e e x p e r i -m e n t a l group 240 113. The p r e d i c t i o n o f a p p a r e n t d i g e s t i b i l i t y o f d r y m a t t e r from f e c a l p r o t e i n c o n t e n t , f o r t h e c o n t r o l group 2.41 114. The p r e d i c t i o n o f a p p a r e n t d i g e s t i b i l i t y o f d r y m a t t e r from f e c a l p r o t e i n c o n t e n t , f o r t h e e x p e r i m e n t a l group 241 115. The p r e d i c t i o n o f f e e d i n t a k e / k i l o g r a m body weight: f r o m f e c a l p r o t e i n c o n t e n t , f o r t h e c o n t r o l group . . . . . . . 243 116. The p r e d i c t i o n o f f e e d i n t a k e / k i l o g r a m body w e i g h t from f e c a l p r o t e i n c o n t e n t , f o r t h e e x p e r i m e n t a l group . 24 3 117. A c o m p a r i s o n o f t h e change i n u r i n e volume between t h e c o n t r o l and e x p e r i m e n t a l groups o f sheep 24 5 118. A c o m p a r i s o n o f t h e average a b s o l u t e p r o t e i n l o s t i n t h e u r i n e , between t h e c o n t r o l and e x p e r i m e n t a l groups 246 119. S e a s o n a l changes i n a b s o l u t e f e c a l and u r i n a r y p r o t e i n l o s s / g r a m o f f e e d i n t a k e f o r t h e c o n t r o l group on w i n t e r range f o r a g e 249 120. S e a s o n a l changes i n a b s o l u t e f e c a l and u r i n a r y p r o t e i n l o s s / g r a m o f f e e d i n t a k e f o r t h e e x p e r i -m e n t a l group on w i n t e r and summer range f o r a g e 25 0 121. A c o m p a r i s o n o f t h e s e a s o n a l c o u r s e o f a b s o l u t e f e c a l and u r i n a r y p r o t e i n l o s s / g r a m o f i n g e s t e d p r o t e i n f o r t h e c o n t r o l group on w i n t e r range f o r a g e 253 xxiv Figure v Page 122. A comparison of the seasonal course of absolute f e c a l and urinary protein loss/gram of ingested protein for the experimental group on winter and summer range forage 251 123. The average d a i l y water intake for the adult ewe group 258 124. The r e l a t i o n s h i p between water intake and d i g e s t i b l e energy intake for the adult ewe group 259 125. The r e l a t i o n s h i p between water intake and d i g e s t i b l e energy intake for the control group. 260 126. The r e l a t i o n s h i p between water intake and the d i g e s t i b l e energy intake for the experimental group 260 127. A comparison of the average water intake between the control and experimental groups, by month. 261 128. The r e l a t i o n s h i p between water intake and the d i g e s t i b l e energy intake/kilogram body weight for the control group ., . . . . . . 262 129. The r e l a t i o n s h i p between water intake and d i g e s t i b l e energy intake/kilogram body weight for the experimental group 262 130. The r e l a t i o n s h i p between body weight change and d i g e s t i b l e energy/kilogram body weight for the control group 265 131. The r e l a t i o n s h i p between body weight change and d i g e s t i b l e energy/kilogram body weight for the experimental group 265 132. The r e l a t i o n s h i p between body weight change and d i g e s t i b l e energy/kilogram body weight-75 for the co n t r o l group 267 133. The r e l a t i o n s h i p between body weight change and d i g e s t i b l e energy/kilogram body weight*75 f o r the experimental group 267 XXV ACKNOWLEDGMENTS A study of t h i s type encompasses many d i s c i p l i n e s on i t s pathway to completion. In p a r t i c u l a r I am extremely g r a t e f u l to my supervisor, Dr. I. McTaggart Cowan, for h i s patience, encouragement and many suggestions throughout the project. Dr. V.C. Brink of the Department of Plant Science aided i n i d e n t i f y i n g many of the alpine and winter range plant species which were unfamiliar to me. Dr. A. J . Wood, of the University of V i c t o r i a , Dr. E. McEwan, Canadian W i l d l i f e Service and Dr. R. Hudson, Department of Animal Science, put forth several h e l p f u l suggestions during the organization and wri t i n g of the manuscript. Several organizations and people aided i n various aspects of the study. In t h i s regard I wish to express my sincere appreciation to: the B.C. Fish and W i l d l i f e Branch for the use of t h e i r s i c k l e mower and species composition data, Mr. I. Derics of the Department of Plant Science, members of the Canadian W i l d l i f e Service and National Parks Branch for t h e i r a i d i n capturing the experimental animals and Mrs. D. Lauriente for her computer analysis of my data and production of several f i g u r e s . The physical aspects of t h i s study were such that i t required substantial funding to undertake. I t i s e s p e c i a l l y s a t i s f y i n g to have such funds avai l a b l e and the f a i t h of one's supervisor when working-on an animal species" that has very r a r e l y been raised successfully under experi-mental conditions. It would have been v i r t u a l l y impossible to have completed t h i s study without the aid of my family. My brother, Keith, supervised much of the painstaking task of c o l l e c t i n g forage, aided me during trapping operations and maintained the animal unit i n my absence. My parents were extremely h e l p f u l during a l l phases of my graduate program allowing me the use of a l l t h e i r f a c i l i t i e s and a great portion of t h e i r time. It was g r a t i f y i n g to maintain a way of l i f e for myself, my wife and children that was compatible with the study and i t s academic commitments and.this period w i l l undoubtedly remain as one of the pleasant memories of my l i f e . INTRODUCTION Sheep, (Ovis canadensis canadensis, Shaw) along with most other ungulates of the mountainous areas of Canada undertake seasonal migrations to and from high alpine ranges. A l t i t u d i n a l migration i s an important but not unvaried feature of behaviour in these areas. The downward migration appears to be weather induced while the motivation f o r the upward movement appears to be food oriented. Capp (1968) suggests that separate summer and winter ranges e x i s t i n almost a l l l o c a l i t i e s , although the degree of separation varies greatly. The widespread occurrence of a l t i t u d i n a l migration Is strong evidence f o r i t s s u r v i v a l value. The nature of t h i s advantage i s unknown. The known fa c t s of phenology and the associated changes i n the chemical composi-t i o n of plants suggest that one of the probable advantages to be gained i s improved n u t r i t i o n . Recent observations have pointed out that c e r t a i n populations of bighorn sheep i n the East Kootenay region of B.C. remain on snow free alpine ranges through part or a l l of the winter months. Most populations u t i l i z e d i f f e r e n t ranges between seasons. In Jackson Hole, Wyoming, Martinka (1969) has shown that a s i g n i f i c a n t portion of the elk population remains i n the v i c i n t y of the winter range throughout the summer. The adequate range and pattern of feeding (grasses i n e a r l y summer, forbs i n midsummer and a l f a l f a i n late summer) appears to compensate for the non-migratory behaviour. There i s evidence that u t i l i z a t i o n of these ranges for 12 months of the year has decreased the forage available to wintering populations. There are few data upon differences i n s u r v i v a l , or of reproductive success, i n migratory versus sedentary populations of large game animals i n mountainous t e r r a i n . However, Morgan (1968) states that 10 percent of the Morgan Creek bighorn population has become non-migratory. In the spring of 1967, ewes, of t h i s population, which remained on the winter range throughout the summer were, almost t o t a l l y unsuccessful i n r a i s i n g lambs. The objective of the present study i s to explore the advantages of a l t i t u d i n a l migration, i f they e x i s t , the nature of t h i s improvement, and whether i t i s great enough to be s i g n i f i c a n t to the migrants. The mechanism of s u r v i v a l could operate at the l e v e l of the population or the i n d i v i d u a l . This could mean, at the population l e v e l , that a population remaining throughout the year on the low ranges experiences reduced s u r v i v a l or raises fewer young. I t could a r i s e from use of feed during the summer that would otherwise be a v a i l -able during the winter thus reducing the capacity of the winter range during the winter period. 3 Populations remaining on low ranges could deny themselves access to longer periods upon vegetation of a higher q u a l i t y and thus experience poorer n u t r i t i o n a l circumstances. This influence would f i n d expression especi-a l l y i n growing animals; through less e f f i c i e n t l a c t a t i o n by the mother or through a less d i g e s t i b l e weaning d i e t . The outcome could be lowered s u r v i v a l rates or young with a lower growth rate, smaller size i n autumn and a longer period to maturity. Advantages gained by migration could be a greater d i v e r s i t y of plant species available as feed; the p o s s i b i l i t y of prolonging access to plants i n an early stage of growth and thus increasing the t o t a l consumption of plant nutrients abundant i n early growth stages (e.g. protein and phosphorus) as opposed to those characterizing the mature stage of plant growth (e.g. calcium, crude f i b r e ) . This study i s designed to examine the assumption that an important advantage to the i n d i v i d u a l and through them to the population i s to be found i n the d i f f e r e n t i a l n u t r i t i o n of migratory versus non-migratory populations of bighorn. If the above hypothesis i s tenable, i t should be possible to demonstrate differences in n u t r i t i o n a l states and some of t h e i r concomitants between two groups of animals; one maintained s o l e l y on winter range feed and the other alternated between summer and winter range feed. This study was designed to examine the n u t r i t i o n a l advantages of migra-t i o n using c a p t i v e animals fed n a t u r a l d i e t s obtained from ranges a v a i l a b l e to w i l d l i v i n g bighorns i n a regime a p p r o x i -mating t h a t of migratory and non-migratory f l o c k s . Evidence of d i f f e r e n c e s between the two groups was sought i n terms of feed i n t a k e , weight g a i n , apparent d i g e s t i b i l i t y , apparent d i g e s t i b l e energy and p r o t e i n , n i t r o g e n balance and phosphorus i n t a k e . DESCRIPTION OF THE STUDY AREA The study area i s centered i n the Rocky Mountain Trench between Elko and Premier Ridge (49° 20' to 50 north l a t i t u d e ) B r i t i s h Columbia. The Trench i s a l o n g i t u d i n a l , g l a c i a t e d depression extending from Montana to the Yukon. The Rocky Mountains r i s e a b r u p t l y from the v a l l e y f l o o r on the east and on the west the P u r c e l l Mountains begin as rounded and wooded f o o t h i l l s , which give way to rugged mountains (Holland, 1964). The c l i m a t e i s such t h a t there i s higher p r e c i p i t a -t i o n i n winter than i n summer and a high p r o p o r t i o n of snow-f a l l . I t i s semi - a r i d w i t h a range i n mean annual p r e c i p i t a -t i o n between about 14 and 17 inches. The h e a v i e s t f a l l s of r a i n and snow are on the western slopes ( K e l l e y and H o l l a n d , 1961). The area i s c h a r a c t e r i z e d by four major v e g e t a t i o n zones: The Ponderosa pine-bunchgrass zone w i t h i t s l i g h t and dark brown s o i l s occurs at an elevation of approximately 2500 feet; the I n t e r i o r Douglas f i r zone has the o r t h i c brown s o i l s at an elevation of 2000 to 4500 feet; the Engelman spruce-subalpine f i r zone has o r t s e i n podzol s o i l s at an elevation of 3500 to 5500 feet; the alpine zone with i t s t h i n humus s o i l s occurs around 7000 feet (Krajina, 1965). The aspect of the slope w i l l a f f e c t the el e v a t i o n a l l i m i t s of each zone, to some degree. In the East Kootenay region, bighorn sheep inhabit the western slope of the Rocky Mountains from the Crowsnest Pass and B u l l River north to just south of Golden. There are no authentic records for Rocky Mountain bighorn in the Selkirk or P u r c e l l ranges on the west side of the Trench (Cowan and Guiguet, 1965) . METHODS AND MATERIALS Animal Methods Experimental animals. Three adult females and a 4.5 year old male bighorn from Waterton National Park and a male lamb of the same species from the Wigwam area, i n the Rocky Mountain Trench, were the experimental animals f o r the f i r s t year of the study (1968) . In 1969, the adult sheep were released and four y e a r l i n g female Rocky Mountain bighorn were obtained from Waterton and Banff National Parks to make up a group of 5 animals of even age. Two of these ewes formed the control group to represent the sedentary behaviour of animals remaining throughout the year on the winter range. The other three animals formed the experimental group which p a r a l l e l e d changes encountered by migratory, f r e e - l i v i n g bighorn as they moved from the winter to summer ranges and back to the winter range i n the autumn. Body weight change. Digestion t r i a l s were conducted at approximate monthly i n t e r v a l s during 1969-70, wherein actual d a i l y body weight change was obtained f o r each d i e t from weights taken before and a f t e r each 7 day digestion t r i a l . Therefore, actual weight change/month was determined from weekly weighings. In contrast, the calculated body weight for each month was determined as follows: weight change/digestion t r i a l X4 + body weight of previous month. This method was used to ascertain the maximum monthly body weight that could be achieved by the sheep, on each d i e t . The period of measured weight change (7 day digestion t r i a l ) was extrapolated over the three week period preceding the t r i a l . Calculated weights were obtained at monthly i n t e r v a l s i n order that a s p e c i f i c rate of gain at a p a r t i c u l a r body weight would not tend to overestimate max-imum growth (an animal gaining 1 pound/day at 98 pounds BW w i l l not do so at 150 pounds BW). Whereas actual weight measurement at weekly i n t e r v a l s included the behavioural i n t e r a c t i o n between the animal and the experimentor, the method using calculated weights reduced the behavioral i n t e r a c t i o n by using the maximum rate of gain obtained i n a 7 day t r i a l and extrapolating i t over the preceding three week period. Digestion t r i a l pens. Pens were constructed within a large unheated b u i l d i n g , giving shelter from wind, r a i n and snow throughout the year. Each pen was a 6 x 8 foot metabo-lism cage i n which the animal was maintained. The frame consisted of 2 x 4's, the walls and door of 3/8 inch plywood and the f l o o r was made of 2 x 2's with a 3/4 inch space between each member. Each pen was painted with outdoor enamel 8 to a height of four feet to f a c i l i t a t e cleaning. Feed trays and watering devices were constructed as described by Wood et a l . (1961). Feed boxes were 20 x 14 x 12 inches and were designed to hold natural forages. Water b o t t l e s , hoses and bowls were wrapped with 75 watt heat tapes and 2 inch f i b r e i n s u l a t i o n to prevent freezing i n winter. This system was adequate to -40°F. A l l pens were connected with drop gates 30 x 16 inches, so that animals could be run through the pens and into a weighing box. Digestion t r i a l s . The pens were b u i l t 18 inches above the f l o o r to allow c o l l e c t i o n of feces and urine. Feces were c o l l e c t e d on a screen of 1/4 inch mesh and urine on an i n c l i n e d polyethlene s t r i p , placed beneath the screen. Urine was removed d a i l y from a c o l l e c t i n g v e s s e l . Total feed and water intake were measured each day for a 7 day period and d i g e s t i b i l i t y figures calculated from the oven dry weights of feed and feces. Preliminary periods were approxi-mately 18 to 24 days. Animals were weighed every 7 days and before and a f t e r each t r i a l . Scouring. The pens were washed and d i s i n f e c t e d approximately every 3-4 weeks but oc c a s i o n a l l y animals contracted scours. The treatment consisted of 1 cc. of p e n i c i l l i n , injected intramuscularly the f i r s t day, three tabl e t s of aureomycin for each of three days and eight ounces 9 o f kaopectate f o r each o f two s u c c e s s i v e days, depending on the s e v e r i t y of the i n f e c t i o n . T h i s treatment r e s u l t e d i n the complete r e c o v e r y o f a l l animals. P l a n t Methods D i e t s . In d e s i g n i n g the experimental d i e t s i t was necessary to c o n s i d e r the s p e c i e s i n c l u d e d , the p r o p o r t i o n of g r a s s e s , f o r b s and shrubs as w e l l as the p a r t s of the p l a n t s used. To do t h i s , a p p r o p r i a t e l i t e r a t u r e was c o n s u l t e d , (Wasser, 1940; Honess and F r o s t , 1942; Murie, 1944; Cowan, 1947; Smith, 1954; Moser, 1962; Blood, 1967; Longhurst e t a l . 1968; Capp, 1968; Constan, 1969; Wilson, 1969; Lesperance e t a l . 1970). These f i n d i n g s were supplemented by s e l e c t i v i t y t r i a l s made i n the pens and by o b s e r v a t i o n of my completely tame ram w h i l e f r e e r a n g i n g . In g e n e r a l , s u b j e c t to seasonal a v a i l a b i l i t y , b i g h o r n s e l e c t 65-90 p e r c e n t g r a s s and g r a s s l i k e p l a n t s d u r i n g a 12 month p e r i o d and the remainder f o r b s and shurbs. There i s some seasonal v a r i a t i o n i n the forage mix w i t h the p r o p o r t i o n of g r a s s h i g h e s t i n the s p r i n g and on a l p i n e areas and lowest d u r i n g the w i n t e r months. There i s g e n e r a l agreement t h a t bluebunch wheatgrass* i s the key s p e c i e s and Constan (op. c i t . ) s t a t e s t h a t t h i s s p e c i e s , along w i t h rough fescue comprise over h a l f o f the * • See Appendix A f o r a l i s t o f common and s c i e n t i f i c names f o r p l a n t s p e c i e s . 10 w i n t e r d i e t on Montana ranges, e q u i v a l e n t to the d i e t a r y composition of the winter range forage used i n t h i s study. C o l l e c t i o n of forage. The Hughes and Galton ranges of the Rockies form the eastern boundary of the Rocky Mountain Trench and t h e i r f o o t h i l l s c o n t a i n some of the key winter ranges f o r bighorn sheep. Winter forage was cut from three main winter ranges: the east side of Premier Ridge, e l e v a t i o n 4000 f e e t ; along the banks of the B u l l R iver e l e v a t i o n 2700 f e e t ; and on the southwest slopes bordering the E l k R i v e r at E l k o , e l e v a t i o n 3000 to 3500 f e e t (Wigwam winter range). Summer range forage (subalpine and a l p i n e areas) was cut i n basins and s l i d e s of the Hughes range. Subalpine s l i d e s occurred between 5000 to 6000 f e e t and a l p i n e basins were above 6500 f e e t . S i m u l a t i o n of n a t u r a l d i e t s . Forage was obtained from winter and summer ranges f o r two years (1968 and 1969), w i t h the a i d of two a s s i s t a n t s c u t t i n g by hand and the use of a gas powered s i c k l e mower. I t was a i r d r i e d to approximately 10 (9 to 11.5) percent moisture and stored i n burlap sacks hung above the f l o o r , i n the weather t i g h t b u i l d i n g housing the experimental animals. Approximately 5000 pounds; 2000 pounds Kentucky bluegrass and c l o v e r from the Wigwam winter range and 3000 pounds (75 to 95 percent bluebunch wheatgrass) from Premier Ridge, B u l l R i v e r and the Wigwam range was cut from May to 11 September of 1968, while 6500 pounds was cut from A p r i l to the end of October 1969. The l a t t e r cut was mainly bluebunch wheatgrass.. Alpine forage was cut i n August 1968 and from l a t e June u n t i l the end of September 1969. Over-wintered forage from the winter range was cut during March 197 0. Forage was cut to ground l e v e l during A p r i l and May on the winter range and at a l l times on the summer range. Forage on the winter range during June, July and August was cut to 3 to 5 inches above the ground. Dormant forage, c o l l e c t e d from July u n t i l October 28 was' cut approximately 3 inches above ground using a s i c k l e mower. Bluebunch wheatgrass was s e l e c t i v e l y cut on the winter ranges so that i t contained mainly leaves. Three d i f f e r e n t d i e t s were cut i n October, from various winter ranges, and fed during the winter of 1969-70: 1) 40-50 percent bluebunch wheatgrass; the remaining 50-60 percent being Idaho and rough fescue, pine grass, June grass, needle grasses and browse, 2) no bluebunch wheatgrass; the d i e t contained a l l of the above species comprising 50 - 60 percent of the previous d i e t , 3) a Kentucky bluegrass d i e t (85-95) percent) with 5 percent other grasses and about 5 percent browse. Species composition of the d i e t was determined by cutting a s t r i p 1 x 10 feet i n a representative s i t e where cutting was taking place and then hand separating the material. Where necessary a sample was taken from the feed during the digestion t r i a l and hand separated. Analysis of samples. Forage, cut on the winter and summer ranges, was f i e l d dried to approximately 10 percent and fed to the captive sheep i n t h i s condition. A l l further c a l c u l a t i o n s ; apparent d i g e s t i b i l i t y , (ADM), apparent di g e s t -i b l e protein (ADP or DCP) and energy (ADE or DE) etc., were done on an oven-dried basis. Forage and f e c a l samples were a i r dried, stored i n p l a s t i c bags and frozen. Urine was subsampled each day on a percentage basis and s u l f u r i c acid added to preserve i t . The sample was stored i n a glass container and frozen. Forage and f e c a l samples were ground i n a Wiley m i l l , oven dried at 105° centrigrade (A.O.A.C. 1965) to a constant weight and the moisture content determined by subtraction. Future measurements using the experimental animals (feed intake, ingested protein (IP) and energy (IE), apparent d i g e s t i b l e drymatter-ADM, protein-ADP and energy-ADE and nitrogen balance) were done iising forage on a dry matter basis. Analysis f o r crude protein (CP) ( t o t a l nitrogen: NH^, NO2, N 03 ' & amino acids, etc.) i n the feed, feces and urine was done according to the macro-Kjeldahl method (A.O.A.C. 1965) and each sample was duplicated or i n some cases t r i p l i c a t e d so that v a r i a t i o n remained below .05 percent. Some urine samples were also analyzed f o r t o t a l nitrogen by the method of Chapman and Pratt (1961). Differences between the methods were n e g l i g i b l e . A quick t e s t f o r n i t r a t e s proved negative , 13 (Muller and Wideman, 1966). Gross energy (GE) determinations were done on feed and f e c a l samples using a Gallenkamp bomb calorimeter. A l l samples were duplicated. Total phosphorus determinations were performed on feed samples by Mr. B. yon Spindler of the Department of S o i l Science, University of B.C. using the Bray method of Black (1965). Range studies. Range studies were begun during the summer of 1968 and i n t e n s i f i e d during 1969. Forage moisture was determined at various i n t e r v a l s i n 1968 and each month from May to October of 1969. Deter-minations were made on a composite grass sample (key species) c o l l e c t e d a f t e r three p r e c i p i t a t i o n free days, from the same general area and from slopes approximately equal i n aspect. A more standardized method i s necessary (humidity, slope r a d i a t i o n , etc.) to achieve completely reproducible r e s u l t s . Phenology was determined monthly by the B.C. F i s h and W i l d l i f e Branch, (in l i t t ) from May to September of 1968. In 1969, I recorded phenological growth stages for key species from A p r i l u n t i l November. This consisted of measuring l e a f length and/or recording growth stages from f i v e i n d i v i d u a l plants for each of the key grass species. The basic species composition for the three winter ranges was obtained from the B.C. F i s h and W i l d l i f e Branch 14 ( i n l i t t ) . They f o l l o w e d the method of Poulton and T i d s a l e (1961) f o r s e l e c t i o n and la y o u t of macroplots and Daubenmire (1959) f o r o b t a i n i n g canopy-coverage and frequency of. occur-rence. A d e t a i l e d d e s c r i p t i o n of the species composition of the B u l l R i v e r and Wigwam ranges i s given i n Appendix B . S i t e s L-2 and L-3 are steep slopes ungrazed by c a t t l e but u t i l i z e d by bighorn sheep. Forage c o l l e c t e d a t B u l l R i v e r was taken from s i m i l a r s i t e s . S i t e s W-l, 2 and 3 on the Wigwam range d e s c r i b e v a r i o u s communities on the range which are used by bighorn sheep. RESULTS Climatic and Forage Differences Between Years The period of study, 1967-70, encountered great differences between the growing period of each year and between the winters separating each growing period. The winters of 1967-68 and 1969-70 could be considered mild, with a l i g h t snowfall (Table 1) and r e l a t i v e l y mild temperatures. This resulted i n a short c r i t i c a l winter period (January and February) of both years and an early spring green-up. P r e c i p i t a t i o n was lowered, presumably r e s u l t i n g i n lowered p r o d u c t i v i t y and reduced succulence of the forage. The l i g h t snowpack of the two years d i d not knock down over-wintering forage and therefore did not allow ungulates to graze much of the spring growth u n t i l i t reached 4 to 6 inches i n height and emerged from the previous years growth. Observations showed that con-siderably less spring growth had been grazed i n 1968 than i n 1969. This i s believed to have reduced the average nutrient, intake of sheep grazing on the winter ranges during the early spring. The proportion of old growth to new, avail a b l e to sheep, i s shown i n Table 2. The winter of 1968-69 was severe, with temperatures to -50°F and snow depths of three to four feet or more, on winter ranges (Table 1). The extremes i n snow depth extended 1967 - 1968 1968 - 1969 1969 - 1970 Description Precip- Precip- Precip-of Period Month i t a t i o n Total Month i t a t i o n Total Month i t a t i o n T o t a l November .61 November 1.23 November .11 Winter Preceding December 1.71 December 4 .69 December 1.31 The Growing Period January 2.54 5.83 January 3.96 11.15 January 1.58 3.68 Dormant Period February .47 February .78 February .47 March .50 March .49 March .21 A p r i l .46 A p r i l 1.52 A p r i l .86 May 3.13 May 2.53 May 1.23 Growing Period June 1.15 9 .02 June 6.02 11.62 June 1.71 July .94 July .34 July .67 6.75 August 1.39 August Trace August .62 September 1.95 September 1.21 September 1.66 Cured Stage October 1.11 1.11 October .40 .40 October .55 .55 Annual Total 15.96 23.17 10.98 TABLE 1. Monthly and yearly p r e c i p i t a t i o n records from the Cranbrook Airport for the three growing years studied. 17 Previous Snowpack Light Heavy Light Year 1967-68 1968-69 1969-70 Date July 3 July May 20 June 22 July 24 Percent New Growth 59 95-100 19.17 64.50 82.80 Percent Old Growth 41 0-5 80.83 35.40 18.20 TABLE 2. The proportion of previous year 1s forage to the current year's growth, using bluebunch wheatgrass as the in d i c a t o r species. (Percentages based upon f i e l d dried weights). 18 from l a t e December to the middle of March. This lengthened ' the c r i t i c a l period during which ungulates must obtain food and withstand cold temperatures. Winter mortality was higher than usual and during the f a l l of 1969 i t was evident that reproductive success had suffered severely i n many populations. The winter, although harsh, resulted i n many b e n e f i c i a l side e f f e c t s . During March, temperatures rose, snow began to melt at the base of trees and rockbluffs and spring green-up began. The abnormal snow depths produced abundant s o i l moisture and resulted i n greater subsequent forage productivity as compared to the summer of 1968. In June, a record r a i n f a l l of 6.02 inches caused forage to remain green and succulent l a t e r into the summer and greatly aided p r o d u c t i v i t y . The extreme weight of winter snow flattened a l l of the past years growth and allowed spring growth to emerge from old growth when only one to two inches i n height. This resulted i n deer, elk and sheep u t i l i z i n g the e a r l i e s t spring growth in l a t e March and early A p r i l . Almost every bluebunch wheatgrass, rough fescue and balsamroot plant was nipped o f f by grazing animals. The low proportion of previous years growth to current growth i s shown i n Table 2. Observations on the grazing habits of a tame bighorn lamb indicated the d i f f i c u l t y of a grazing animal to s e l e c t high q u a l i t y feed when old growth protected new growing forage. Bighorn tend to p u l l grass blades from t h e i r sheaths rather than nip them o f f . This has recently been supported by Geist (1971) (p. 268) who suggests that a p u l l i n g or plucking type of grazing increases the n u t r i t i o n a l content of each mouthful. During 1968 bighorns ingested considerable quantities of o l d growth while grazing i n t h i s fashion but not i n 1969 when only new growth was av a i l a b l e . ' The amount of old growth vegetation that occurs i n the spring d i e t of bighorns varies d i r e c t l y with the e f f e c t i v e -ness of the previous winter's snowpack i n f l a t t e n i n g the old growth and thus permitting the new growth to 'grow through' and become ava i l a b l e to grazing animals early i n the growing period. During early June, 1968 and 1970, previous year's growth comprised 65-75 percent of the standing forage crop (Table 2) while in 1969 i t was considerably l e s s . This produced a 2.5 percent difference i n absolute crude protein values (Table 3) of random cut forage between June of 1968 and 1969. The difference i n the energy content and the d i g e s t i -b i l i t y of spring d i e t s with considerable old growth (1968 and 70) and l i t t l e old growth (1969) i s s i g n i f i c a n t . There i s a .34 Kcal/gm difference i n June for these years. In the same way the apparent d i g e s t i b i l i t y of the 1969 random c l i p was 26 percent higher than that of 1968. The difference i n crude protein, gross energy (.10 Kcal/ gm), and d i g e s t i b i l i t y i s greatly reduced for July of these years as current year's growth forms the bulk of the standing Date of Sampling Description of Area of Sampling Percent Crude Protein Gross Energy Kcal/gm 1968 June 6 B u l l River Winter Range 7.59 4.11 July 24 Wigwam Winter Range 5.87 4.31 July 20 Premier Ridge Winter Range 4.78 4.24 August 5 Kootenay Base Alpine Area 13.68 4.29 1969 a June 15 Premier Ridge Winter Range 10.06 4.45 July 1-20 Premier Ridge Winter Range 5.97 4.18 Average of July 20 and August 25 Kootenay Base Alpine Range 15.08 4.42 TABLE 3. A comparison of crude protein and gross energy values, for sim i l a r dates, between years, f o r di e t s approximately s i m i l a r i n species composition and phenology. 21 Animal Group Composition of Date of Forage Average Winter Range Diet C o l l e c t i o n D i g e s t i b i l i t y Adult Ewes Mainly Agropyron 90-95 percent Adult Ewes Mainly Agropyron 90-95 percent 1968 June 6 July 24 52 .3 50 .6 Yearling Ewes Yearling Ewes Mainly Agropyron 65 - 70 percent Mainly Agropyron 85' - 90 percent 1969 June 1 - 1 0 July 1 - 1 0 71.84 56.79 TABLE 4. A comparison of d i g e s t i b i l i t y between years (1968 and 1969) on forages approximately s i m i l a r i n species composition and phenology. 22 crop. Alpine forage sampled at approximately the same date i n both years, contained s i m i l a r quantities of crude protein, since no previous year's forage i s present but approximately. .13 Kcal/gm more GE i n 1969 than 1968. The s i t u a t i o n of 1969 i s considered "normal" (Dietz et a l . 1962; McLean and Ti s d a l e , I 9 6 0 ; B l a i s d e l l et a l . 1952) when the proportion of old growth i s minimal and does not mask the changes i n q u a l i t y . This indicates that the drop i n d i g e s t i b i l i t y from June to July of t h i s year i s a d i r e c t r e s u l t of the reduction i n q u a l i t y of the forage rather than to a change i n composition. During 1968, the high propor-t i o n of previous year's growth resulted i n lower average forage q u a l i t y and reduced d i g e s t i b i l i t y (June) to the l e v e l of the July cut forage. D i g e s t i b i l i t y can be influenced by l e v e l of feeding (Blaxter, 1962; p. 192) as well as by q u a l i t y of the feed. In my experiments the l e v e l of feeding was s i m i l a r during June and July, 1968, (982.6 gm/day and 998 gm/day, respec-t i v e l y ) but d i f f e r e d between May (912 gm/day) (28.98 gm/ Kg BW/Day) and July (981.7 gm/day) (29.69 gm/Kg BW/Day)in 1969. A l s o , l e v e l of feeding i s i n part influenced by feed q u a l i t y . Thus, while differences i n d i g e s t i b i l i t y between June and July 1968 and between July 1968 and July 1969 are un l i k e l y to have been due to anything but feed q u a l i t y t h i s cannot be stated for the May - July 1969 period, although feed intake/Kg BW was s i m i l a r . 23 Range Studies Examination of the range variables pertinent to t h i s study included forage moisture, phenology, and species com-pos i t i o n of the range. Following sections on nutrient cycles i n the forage, species composition of the natural d i e t s , feed intake and other measurements of animal n u t r i t i o n are d i r e c t l y r e l a t e d to the above measureable range v a r i a b l e s . Forage moisture. Forage moisture varies greatly from day to day as a r e s u l t of changes i n c l i m a t i c conditions: p r e c i p i t a t i o n , humidity and temperature. Site factors and the proportion of o l d growth present i n the stand also add v a r i a b i l i t y to this determination (Tables 2 & 5). Forage moisture, was determined i n order to approximate d a i l y wet feed intakes of wild sheep using a i r or oven d r i e d feed intake data for captive sheep. Samples c o l l e c t e d during 1969, were taken randomly (Dietz et a l . 1962) and should represent forage growth (mainly new growth) as a v a i l a b l e . The determination of forage moisture from f i e l d samples c o l l e c t e d i n t h i s manner cl o s e l y approximates feed samples given to the sheep, allowing c a l c u l a t i o n of wet,feed intakes. The forage moisture content of winter range grass mixtures was determined from July u n t i l October, 1968, as shown i n Table 5. I t w i l l be seen that growing plants contain more moisture than over-wintered forage or mixtures of the two. Also, s i t e s which appear moister and usually 24 Date Forage of Area Approximate Description Moisture Sampling of Species of F i e l d Dried 1968 Sampling Mixture Sample to 10 Percent July 13 East Side of Premier Ridge July 2 5 Wigwam Range September 6 September " 20 90-95 percent Two Samples Agropyron of green growth  Poa and •Trif olium Poa and T r i f o l i u m Poa and T r i f o l i u m Old and New growth Old growth Dry l o c a t i o n 50 .7 36.7 11.5 36 .1 Moister l o c a t i o n 47.6 33.3 31.2 TABLE 5. Forage moisture content of two winter range grass mixtures showing v a r i a t i o n due to composition, location and season, 1968. 25 Date of Sampling, 1969 Area of Sampling Approximate Special Mixture Forage Moisture F i e l d Dried to '10 percent A p r i l 29 May 26 June 6 July 14 August 13 September 12 Premier Ridge Agropyron and Winter Range Festuca " Mainly Agropyron, Festuca and Calamagrostis Mainly Agropyron, Festuca, Calama-g r o s t i s , Koeleria, Balsamorhiza 4 0 - 5 0 percent Agropyron 60 45.3 34.2 42.2 35.2 10-15 TABLE 6. Forage moisture content of winter range grass mixtures showing seasonal v a r i a t i o n , 1969. 26 Date o f S a m p l i n g A r e a o f S a m p l i n g A p p r o x i m a t e S p e c i e s M i x t u r e F o r a g e Mois-t u r e F i e l d D r i e d t o 10 p e r c e n t  1968 August 19 Kootenay Base A l p i n e A r e a September 13 Kootenay Base A l p i n e A r e a M a i n l y Sedges Elymus g l a u c u s G r a s s and Sedges 47.7 59.1 47.6 1969 June 17 Kootenay Base G r a s s e s , Sedges 75.2 S u b a l p i n e S l i d e s F o r b s and Browse J u l y 11 " " \ 63.5 J u l y 16 Kootenay Base M a i n l y G r a s s e s , A l p i n e A r e a Sedges and F o r b s 70.7 August 12 " . " 35.7 September 25 " " 45.1 TABLE 7. Forage m o i s t u r e c o n t e n t o f s u b a l p i n e and a l p i n e m i x t u r e s , c o l l e c t e d d u r i n g 1968 and 1969. 27 harbour more luxuriant growth, produce - forage with a higher' water content. A x e r i c and hydric s i t e on the Wigwam range varied by approximately 11-12 percent forage moisture. Average forage moisture declined by approximately 20 percent during the sampling period. Forage moisture i s highest i n young plants, decreasing to a low as plants mature and become dormant (Table 6). This i s the reverse of changes i n crude f i b r e (Richards et a l . 1962) and adds to the succulence and p a l a t a b i l i t y of young plants. Forage moisture declined from 4 5 to 2 0 percent from A p r i l u n t i l mid-September, 1969. An observed increase i n forage moisture during July and August, 1969 i s l i k e l y due to the excessive p r e c i p i t a t i o n at that time, (Table 1). The forage moisture determination of June 6, occurred p r i o r to the excessive p r e c i p i t a t i o n i n June and i s consequently lower than the July and August determination. The alpine areas exhibited a consistently higher.;: moisture content (Table 7) for a l l periods of the summer and f a l l , when compared to winter range areas. This i s probably due to the higher snowpack, continuous water supply throughout the summer and lowered evapo-transpiration due to the lowered ambient temperatures. Thus, forage moisture declined 30 percent from June u n t i l the end of September, yet plants retained as much as 35 to 40 percent moisture at that time. The higher forage moisture content increasing 28 succulence and s o f t n e s s of the le a v e s may a i d i n improving p a l a t a b i l i t y . P l a n t moisture decreases from s p r i n g to f a l l f o r both w i n t e r and summer range p l a n t s ( F i g . 1) y e t the moisture content o f a l p i n e p l a n t s i s about 10 p e r c e n t h i g h e r than t h a t f o r w i n t e r range p l a n t s , when both are i n the e a r l y growth s t a g e . By l a t e September, a l p i n e forage c o n t a i n s about 30 p e r c e n t more moisture than does w i n t e r range f o r a g e . In t h i s s t u d y , the r e l a t i o n s h i p between forage moisture and crude p r o t e i n content was c a l c u l a t e d s e p a r a t e l y f o r a l p i n e and w i n t e r range v e g e t a t i o n . As shown i n F i g u r e 2, crude p r o t e i n i s s i g n i f i c a n t l y r e l a t e d (R = .916; p .= .0014) to forage moisture o f w i n t e r range forage on an a i r - d r y b a s i s . A s i m i l a r r e l a t i o n s h i p f o r L o u i s i a n a forage was examined by Campbell and Cassady, 1964. The s l i g h t d i s c r e p a n c y shown by two o f the lower p o i n t s i s p o s s i b l y due t o the abnormal p r e c i p i t a t i o n a t t h a t t i m e . P r e c i p i t a t i o n exceeded 6 inches d u r i n g June (Table 1). T h i s r e l a t i o n s h i p f o r s u b a l p i n e and a l p i n e ranges ( F i g . 3) i s a l s o s i g n i f i c a n t (R = .957; p = .043). For purposes of p r e d i c t i n g crude p r o t e i n c ontent from forage moisture the f o l l o w i n g r e g r e s s i o n s have been c a l c u l a t e d : Y = .1237 + .2203 x + 18.26 p = .0013 •Y = 7.932 + .1302 x + 20.12 p = .0052 f o r the w i n t e r and summer range f o r a g e s , r e s p e c t i v e l y . S ince the s l o p e of the l i n e s i s not s i g n i f i c a n t l y d i f f e r e n t (F = 2.424; p = .158) the r e s u l t s f o r both ranges 29 FIGURE 1. THE RELATION BETWEEN FORAGE MOISTURE CONTENT OF VENTER AND SUMMER RANGE FORAGES, SHOWING SEASONAL VARIATION. o CRUDE PROTEIN CONTENT IN PERCENT c CRUDE PROTEIN CONTENT IN PERCENT 31 0«0 10-0 50-0 30«0 40«0 50-0 G0»0 70*0 B0»0 FORAGE MOISTURE CONTENT IN PERCENT FIGURE 4.- The r e l a t i o n s h i p between forage moisture and crude protein content of winter and summer range plants, 1969. 32 were combined i n Figure 4. This r e l a t i o n s h i p i s described by the equation: Y = .7750 + .2323 X + 20.13 (p < .000). Phenology. Phenological growth stages were recorded on the winter, subalpine and alpine ranges during 1968,and 1969. Table 8 presents phenology on three winter ranges using bluebunch wheatgrass as the indicator species, since i t i s the most important and commonest grass species on the winter range. Information on other grasses was obtained to complement digestion t r i a l data. Table 9 contains the r e s u l t s of the det a i l e d study of phenology accompanying my digestion t r i a l s during the summer of 1969. There i s a s i m i l a r i t y i n timing of growth stages between years. The greatest v a r i a t i o n occurs during i n i t i a -t i o n of growth and during the f i r s t and second growth stages. This i s influenced by the onset of c r i t i c a l temperature for growth, moisture, snowpack, exposure, etc. As the summer progresses and s o i l temperatures s t a b i l i z e , the growth stages-coincide better between years and ranges. The s i m i l a r -i t y of growth stages between ranges and years w i l l a i d i n describing aspects of the n u t r i t i o n a l status of a grazing animal. At c e r t a i n dates throughout the year s p e c i f i c growth stages w i l l f u rnish approximations.of d i g e s t i b i l i t y , crude Winter Plant Spring 1st Leaf 2nd Leaf 3rd Leaf 4th Leaf Flower Seed Ripe/ Seeds Cured Range Species Growth Stage Stage Stage Stage Stage Mature Shedding Stage Agropyron A p r i l 1-7 A p r i l 20 A p r i l 30 May 15 May 20 June 9 July 3-10 Aug. 10-31 Sept. East Side Festuca April- 1-10 - - - - June 5-9 July 3-10 Aug. 10-31 Sept. Premier Ridge Koeleria A p r i l 15 - - - - June 10-15 July 10 Aug. 10-31 Sept. Balsamorhiza A p r i l 20 - - - May 9 May 26 - J u l y Spirea+ - - - - - July 7-14 Aug. 1-7 - Sept. B u l l River Agropyron A p r i l 1 A p r i l 15 A p r i l 22 A p r i l 30 May 15 June 5-9 July 10 Aug. 10 . Sept. River Bank Tragopogan - - - - - June 25 July 20 Aug. 7-14 Sept. Artemisia - - - - Aug. 7-14 - - Sept. Amelanchier+ - - - - - May 25 July 20 Aug. 20 Sept. Wigwam Agropyron A p r i l 15 A p r i l 26 A p r i l 30 May 15 May 20 June 10 July 10 Aug. 10 Sept. Poa - - - - - - July 20 Aug. 1-31 Oct. 15-30 T r i f o l i u m - - - - - July 1 July 20 - Oct. 15-30 Koeleria+ - - - - - June 25 July 7-14 Aug. 20 -Lomatium+ - - - - - June 14 June 30 July 30 -+ pata from B.C. F i s h & W i l d l i f e Branch Table 8. The timing of the phenological stages of winter range forages for three winter ranges, during 1968. w. Plant Species Premier Ridge S i t e Spring Growth 1st Leaf Stage 3rd Leaf Stage 4th Leaf Stage Flower Stage Seeds Ripe/ Mature Seeds Shedding Cured Stage Agropyron East A p r i l 9 A p r i l 21 May 9 May 26 June 10 July 1-10 J u l y 15-20 Sept. 7.86" 12.06" 13.62" Festuca n A p r i l 1-15 A p r i l 21 - May 9 ' June 1-10 J u l y 14 Aug. 15-Sept. 6.33" 8.66" 11.70" Calamagrostis II - May 26 - - June 11 J u l y 1 Jul y 15 Aug.-Sept. 13.51" Koeleria II - -' - - June 1 June 15 Jul y 1-15 Aug. 15-Sept. Stipa n - - - June 1 June 15 Jul y 15 Aug.-Sept. Bromus+ F l a t s - - - - June 25 J u l y 7 - -Poa+ It - . - - - June 7 . Ju l y 7 Jul y 20 -Balsamorhiza East A p r i l 20 May 9 6" - • - May 26 June 11 J u l y 14 Aug. A c h i l l e a II A p r i l 20 - • - June 10 July' 14 Aug. 1 Aug. 15 Amelanchier+ West _ - - - - June 20 Jul y 7 Aug. _ Purshia+ M - - - - May 25 J u l y 7 Aug. 14 -Spirea-r East - - - - " • June 1-7 Aug. Aug. 20 -+ Data c o l l e c t e d by B.C. F i s h and W i l d l i f e Branch Table 9. The timing of phenological stages of forage from various s i t e s on the Premier Ridge winter range, 1969. 35 protein and gross energy of the forage. I t i s evident from Tables 8 and 9 that grasses begin growth e a r l i e r than other forage types. They also enter the cured stage i n the f a l l e a r l i e r than the browse species l i s t e d but at approximately the same time as the forbs. This may be important in the s e l e c t i o n of feed by bighorn sheep. The progression of growth stages i s delayed in r e l a t i o n to increases i n elevation'. The difference between the E s t e l l a range and the Premier Ridge range (1000 to 1500 feet) was about 2 weeks i n time. Thus, an increase i n elevation of 1000 feet, between these 2 ranges, produced a difference of two phenological stages i n rough fescue (compare Table 10 to Table 9). S i m i l a r i l y , an increase i n elevation of approximately 1000 feet (5000 to 6000 feet on the E s t e l l a range produced a difference of two to three phenological stages i n rough fescue (Table 10). Date Description Area of Phenological Stage Remarks May 31 E s t e l l a winter range Ear l y seed head: 15-20 days Elevation 5000--5500 height 8.86" l a t e r than on f t . Premier Ridge. May 31 E s t e l l a winter range Medium le a f About 30 days elevation 6000--6500 stage: height l a t e r than on f t . 7.78" Premier Ridge. TABLE 10. A comparison of phenological stages of rough fescue on the E s t e l l a winter range, in r e l a t i o n to eleva-t i o n , 1969. Area Plant Type Spring Flower Seed/Fruit Seed/Fruit Cured Growth Staae Staae Shed Staae Wildhorse Grasses June 1-10 July 5-10 July 25-30 August 5 Aug. 25-Sept.1 Subalpine Slides Forbs June 1-10 Ju.ly 3-10 July 2 5-30 August 5 Aug. 25-Sept.1 Browse June 10-15 July 5 July 2 5 August 10 Aug. 25-Sept.1 • Kootenay Grasses July 10 July 30 Aug.5-10 Sept. 10 Frozen Sept.24 Base Alpine Sedges July 3 - July 20 Sept.1-10 Frozen Sept.24 Area Forbs July 3 July 10 -20 Aug.1-10 Sept.1-10 — Browse July 10 July 30 August September Frozen Sept. 24 TABLE 11.. The timing of phenological growth stages of subalpine and alpine forage, • 1968. 37 A l p i n e p l a n t s w e r e a p p r o x i m a t e l y 3 t o 4 m o n t h s l a t e r i n t h e i r d e v e l o p m e n t t h a n w i n t e r r a n g e p l a n t s ( c o m p a r e T a b l e 9 t o 1 1 ) . The. i n i t i a t i o n o f p l a n t g r o w t h i s d e l a y e d a t h i g h e r e l e v a t i o n s due t o s n o w p a c k and l o w e r e d t e m p e r a t u r e s , c o n t i n u i n g i n t o J u n e . The same s e q u e n c e a n d number o f g r o w t h s t a g e s a r e c o n d e n s e d i n t o a s h o r t e r t i m e p e r i o d p r o d u c i n g l e s s v a r i a t i o n i n p h e n o l o g i c a l s t a g e s b e t w e e n y e a r s , t h a n f o r p l a n t s o f t h e l o w e r r a n g e s . The s u b a l p i n e p l a n t s a t b o t h K o o t e n a y B a s e a n d t h e W i l d h o r s e a r e a b e g a n g r o w t h a b o u t t h e f i r s t week i n J u n e ( T a b l e s 11 a n d 1 2 ) . T h i s o c c u r r e d a p p r o x i m a t e l y 2 t o 2.5 m o n t h s a f t e r i n i t i a t i o n o f s p r i n g g r o w t h o n t h e w i n t e r r a n g e s . A l p i n e p l a n t s b e g a n g r o w t h d u r i n g t h e f i r s t h a l f o f J u l y . As shown i n T a b l e 1 2 , t h e d o r m a n t p e r i o d f o r a l p i n e f o r a g e o c c u r r e d when t h e p l a n t s f r o z e a r o u n d t h e end o f S e p t e m b e r . The K o o t e n a y B a s e s u b a l p i n e p l a n t s w e r e c u r e d a n d d r i e d b y S e p t e m b e r p r i o r t o b e i n g f r o z e n . A l t i t u d i n a l m i g r a t i o n a p p e a r s b e n e f i c i a l s i n c e i t a l l o w s a n i m a l s t o r e m a i n on f o r a g e i n e a r l y t o medium l e a f s t a g e s f r o m l a t e M a r c h t o e a r l y A u g u s t . The n u t r i t i o n a l s i g n i f i c a n c e w i l l b e e x p l a i n e d i n l a t e r s e c t i o n s . W i l d g r a z i n g u n g u l a t e s g e n e r a l l y e n c o u n t e r e a r l y g r o w t h s t a g e s and h i g h f o r a g e m o i s t u r e w h i l e i n t h e i r p o o r e s t p h y s i c a l c o n d i t i o n o f t h e y e a r . Y o u n g g r o w i n g p l a n t s s e r v e t o h e i g h t e n t h e n u t r i t i o n o f t h e g r a z i n g a n i m a l by p r o v i d i n g maximum s u c c u l e n c e , r e l a t i v e t o m a t u r e p l a n t s , n u t r i e n t Area Plant Type Spring Growth Early to Late Leaf Stage Flower Stage Seed/Fruit Stage Seed/Fruit Shed Kootenay Base Grasses Subalpine S l i d e s Sedges Forbs Kootenay Base Alpine Areas Browse Grasses Sedges Forbs June 1 - 5 May 27-June 1 June 1 June 1-5 J u l y 8-10 J u l y 5 J u l y 8-10 June 19 June 5-10 June 19 June 19 July 15 July 10-15 Jul y 10-15 J u l y 11-16 June 20 Jul y 10-15 Jul y 15 Jul y 20-30 J u l y 15-20 Jul y 15-20 Jul y 15-30 July 11 Jul y 20 Jul y 20-30 Aug. 10-15 July 25 Jul y 25-30 Aug. 10-15 Aug. 1-10 Aug. 10-15 Aug. 1-10 frozen Dt. 23 s e p  frozen Dept. 23 Jrozen at. 23 Table 12. The timing of phenological growth stages of subalpine and alpine forage, 1969. CO 39 intake and the lowest crude f i b r e content; thereby increasing p a l a t a b i l i t y (Sullivan, 1962). Species composition of three winter ranges. The f l o r i s t i c composition of three winter ranges was determined by the B.C. Fish and W i l d l i f e Branch i n 1967 using the macroplot method of analysis. This ent a i l e d a description by canopy coverage and frequency of occurrence i n percent* On the east side of Premier Ridge, bluebunch wheat-grass i s the most important species and occurs most frequently by both methods of analysis (Table 13). Idaho fescue ranks second and June grass t h i r d . The most common forbs are sunflower and yarrow. Saskatoon berry and f l a t -top spirea are the most common and important shrubs. On the B u l l River range, forage was cut from s i t e s ungrazed by c a t t l e (Table 14).* Bluebunch wheatgrass comprises about 55 percent by canopy cover and 100 percent by frequency of occurrence. June grass i s the next most common grass. The forbs appear to be equally ranked i n occurrence, averaging 3.3 percent by canopy cover and 25 percent by frequency of occurrence. S i m i l a r l y , on the Wigwam range (Table 14 blue-bunch wheatgrass i s the dominant species, while June grass and Idaho fescue rank second and t h i r d . Yarrow and lomatium comprise the bulk of the forbs. *See Appendix B for a de t a i l e d d e s c r i p t i o n of the species composition (Tables 15 and 16). Description Plant Species Canopy Coverage/Freq-uency of Occurrence Agropyron spicatum Calamagrostis rubescens Festuca idahoensis Grasses Festuca s c a b r e l l a Koeleria c r i s t a t a A c h i l l e a m i l l e f o l i u m Allium cernuum Forbs Antennaria rosea Aster spp. Astragalus miser Balsamorhiza s a g i t t a t a Epilobium alpinum Fragaria v i r g i n i a n a Hieracium spp. Amelanchier a l n i f o l i a Arctostaphylos Shrubs uva-ursi Populus tremuloides Pseudotsuga menziesii Rosa spp. Spirea b e t i f o l i a Elevation Site Features Slope Cover of vascular plants 45/97 t/5 18/75 t/1 14/83 1/23 1/6 t/3. t/3 1/5 10/41 t/3 t/1 t/5 3/10 t 1/7 t/1 3/17 2/33 3900 feet 42 percent 58 percent ? Collected by the B.C. Fish and W i l d l i f e Branch TABLE 13. The percent canopy coverage and frequency of occurrence for the Douglas fir-bunchgrass vegetation type of the east side of Premier Ridge. B u l l River Wigwam Winter Range Forage Canopy Cover/ Canopy Cover/ Type Plant Species Freq. of Occurrence Freq. of Occurrence Agropyron spicatum 54.7/100.0 32/95 Grass Festuca idahoensis - 5/36 Bromus tectorum 4/17 -Koeleria c r i s t a t a 7.5/45 20/97 Forbs A c h i l l e a m i l l e f o l i u m 2/20 2.5/20 Allium cernuum 1.5/24 Fragaria v i r g i n i a n a 3/16 Lomatium macrocarpum 8.2/78 Monarda f i s t u l o s a 6/64 Chrysopsis v i l l o s a 5.6/42.5 Epilobium minutum 2.8/36 Linum perenne 2.5/28.8 Shrubs Amelanchier a l n i f o l i a 7/27.5 Purshia t r i d e n t a t a 12.4/37.5 Symphoricarpus albus 10/67.5 10/70 Rosa woodsii TABLE 14. The percent canopy coverage and frequency of occurrence for the Agropyron-Purshia Community of the B u l l River Area and for the Wigwam Winter Range. 42 The i m p o r t a n c e o f b l u e b u n c h w h e a t g r a s s as a range f o r a g e i s e v i d e n t on e x a m i n a t i o n o f i t s f r e q u e n c y o f o c c u r r e n c e on t h e t h r e e w i n t e r r a n g e s (100 p e r c e n t ) . I t forms a p p r o x i m a t e l y 45 p e r c e n t o f t h e canopy c o v e r o f t h e t h r e e r a n g e s . I t s f r e q u e n c y o f use by sheep has been r e p o r t e d p r e v i o u s l y and b e a r s a d i r e c t r e l a t i o n s h i p t o i t s a v a i l a b i l i t y a l o n g w i t h i t s o t h e r i m p o r t a n t p h y s i c a l f a c t o r s ( a b i l i t y t o w i t h s t a n d heavy s n o w f a l l s ) . I t s i m p o r t a n c e i n t h e n u t r i t i o n a l s t a t u s o f g r a z i n g a n i m a l s w i l l be examined-i n l a t e r s e c t i o n s . The h i g h o c c u r r e n c e o f g r a s s e s on t h e v a r i o u s w i n t e r r a n g e s i n t h e E a s t Kootenay i n c o m p a r i s o n t o f o r b s and browse i s e v i d e n t on e x a m i n a t i o n o f T a b l e s 13 and 14. T h i s f a c t , a l o n g w i t h s e l e c t i o n t r i a l s done i n t h e f i e l d and under c o n t r o l l e d c o n d i t i o n s and i n f o r m a t i o n f rom t h e l i t e r a t u r e on f o o d h a b i t s r e s u l t e d i n t h e f o r m u l a t i o n o f e x p e r i m e n t a l - d i e t s shown i n a f o l l o w i n g s e c t i o n . S e l e c t i o n between Forages under C o n t r o l l e d C o n d i t i o n s F orage s e l e c t i o n t r i a l s were c o n d u c t e d t o d e t e r m i n e t h e r e l a t i o n s h i p between b i g h o r n d i e t s d e s c r i b e d i n t h e l i t e r -a t u r e and t h e a c t u a l d i e t s t o be f e d t o t h e c a p t i v e band. I u n d e r t o o k f i e l d s e l e c t i o n t r i a l s u s i n g a tame, i m p r i n t e d b i g h o r n w h i l e i n t h e lamb and y e a r l i n g c l a s s e s (1968 and 1969). The v a l i d i t y o f t h i s a p p r o a c h i s i n d i c a t e d i n s t u d i e s comparing s e l e c t i o n o f n a t u r a l browse by pen r a i s e d fawns 43 and wild trapped deer (Longhurst et a l . 1968). Selection t r i a l s i n the pens were conducted by presenting each animal with 8 ounces of each of two species or mixtures for a s p e c i f i e d time. F i e l d s e l e c t i v i t y t r i a l s c a r r i e d out on Premier Ridge winter range related the proportion of each plant type selected to i t s occurrence on the range (Table 17). Approx-imately 3 inches of snow covered the range at the time of the t r i a l . Bluebunch wheatgrass and rough fescue were selected most frequently during the f i e l d t r i a l , consistent with t h e i r high degree of a v a i l a b i l i t y . I t appeared that browse was selected s l i g h t l y higher than i t s a v a i l a b i l i t y on the range. The proportion of each plant type selected coincided with that described i n the l i t e r a t u r e and provided a basis fo r the fomulation of the simulated winter range d i e t s composed of natural forages. The subalpine and alpine f i e l d t r i a l s indicated a high preference for forbs (80 to 85 percent). Browse and grasses showed minimal s e l e c t i o n . The f i e l d data are not i n accordance with that presented i n the l i t e r a t u r e nor with s e l e c t i o n t r i a l s i n the pens (see following pages). This difference suggests that the growing forbs, confronted by our free-ranging animal, may have been more palatable than the same species cut for s e l e c t i o n i n the pen t e s t s . Also, growing forbs protruded above the grasses producing a Forage Type No. of Choices Percent Selection Occurrence of Species Date of Type of T r i a l Range Bluebunch Wheatgrass 30 70 .2 45.97 Rough Fescue 3 18/75 Yarrow 2 4 .3 1/23 Bearberry 5 t Douglas F i r 1 25 .5 t/1 Flat-top Spirea 2 2/33 Saskatoon Berry 4 3/10 December 4 19 6 8 Premier Ridge Winter Range Subalpine Sli d e Forbs 78 Grass and Sedges 2 Browse 12 84.8 2.2 13 Alpine Basin Forbs 54 Grass & Sedges 13 80.6 19.4 June 28 1969 Subalpine Sli d e at Kootenay Base July 17 Alpine Basin at 1969 Kootenay Base x Canopy Coverage and Frequency Occurrence TABLE 17. F i e l d s e l e c t i v i t y t r i a l s using an imprinted Bighorn Sheep, showing a comparison between Premier Ridge Winter Range and two summer ranges. d i f f e r e n c e i n a v a i l a b i l i t y . As shown on T a b l e 18, s u b a l p i n e g r a s s e s and sedges were p r e f e r r e d o v e r f o r b s . The d i f f e r e n c e b e i n g a p p r o x -i m a t e l y 63 p e r c e n t . I n two s e p a r a t e t r i a l s , an a l p i n e m i x t u r e was compared w i t h t h e two dominant w i n t e r range g r a s s e s , b l u e -bunch w h e a t g r a s s and f e s c u e . The a l p i n e m i x t u r e was s e l e c t e d c o n v i n c i n g l y o v e r t h e b l u e b u n c h w h e a t g r a s s . The f e s c u e was s e l e c t e d i n q u a n t i t i e s o n l y s l i g h t l y below t h a t o f t h e a l p i n e m i x t u r e ( T a b l e 1 8 ) . They d i f f e r e d by a p p r o x i m a t e l y 28 p e r -c e n t . B i g h o r n sheep s e l e c t e d a g r a s s m i x t u r e o v e r a browse m i x t u r e when b o t h were i n an e a r l y growth s t a g e . A s e r i e s o f t r i a l s was c o n d u c t e d u s i n g rough f e s c u e i n two p h e n o l o g i c a l s t a g e s , r e p r e s e n t i n g 1000 f e e t o f e l e v a t i o n a l d i f f e r e n c e (6000 1 t o 7000'). Fescue i n t h e e a r l y p h e n o l o g i c a l s t a g e i s s i g n i f i c a n t l y s e l e c t e d o v e r t h a t i n t h e l a t t e r s t a g e ( T a b l e 1 8 ) . S p e c i e s C o m p o s i t i o n o f N a t u r a l D i e t s and Pen Fed D i e t s E x p e r i m e n t a l d i e t s c u t on t h e w i n t e r r a n g e s and f e d d u r i n g 1968-70 were f o r m u l a t e d s e l e c t i v e l y t o f a v o r b l u e -bunch w h e a t g r a s s (50 t o 95 p e r c e n t ) . T h i s was done a c c o r d i n g t o f o o d h a b i t s t u d i e s by o t h e r a u t h o r s , s e l e c t i o n t r i a l s c o n d u c t e d d u r i n g t h i s s t u d y ( T a b l e s 17 and 18) and a v a i l -a b i l i t y o f t h e p l a n t s p e c i e s a c c o r d i n g t o i t s o c c u r r e n c e Nature of Test Number of Length of each F i r s t Choice T r i a l s T r i a l , min. Grams  Second Choice Grams Subalpine Forage (1) Agropyron spicatum i n seed-head stage (2) . 10 511.2 14 .20 Alpine mixture (1) Vs Festuca s c a b r e l l a (2) from Premier Ridge 15 539.6 390 .5 Subalpine Grasses & Sedges (1) Vs. sub-alpine forbs (2) 10 582.20 255 .6 New growth Grass (1) Vs. New growth browse (2) Premier Ridge 11 90 781.0 227.2 Festuca s c a b r e l l a (middle leaf stage) (1) Vs. Festuca s c a b r e l l a (seed head stage)(2) 15 923.0 269 .8 TABLE 18. A comparison of s e l e c t i o n under controlled conditions between winter and summer range forages. 47 on the respective range. The approximate composition of winter and summer range d i e t s used i n 1968, 1969 and l a t e winter of 1970 are shown in Tables 19 to 21. Diets were fed i n order of decreasing forage q u a l i t y during 1968, as w i l l be shown i n l a t e r sections and simulated c l o s e l y the natural progression of forage d e t e r i o r a t i o n on the ranges. Ration 36-57, composed mainly of ground corn, wheat and bran (see Appendix D) and fed i n a p e l l e t e d form represented a superior q u a l i t y r a t i o n . Alpine forage contained 81 per-cent grasses and sedges, 17 percent forbs and 2 percent browse. T r i a l s u t i l i z i n g winter range forage cut during June and July contained 92 to 95 percent bluebunch wheat-grass. The diets u t i l i z i n g bluebunch wheatgrass were s i m i l a r i n percent species composition but varied i n phenology and the percent of old growth present i n a standing bunch CTable 2) . Forage obtained from the Premier Ridge winter range during 1969-70 contained 88 to 99 percent grass (Table 20). Spring t r i a l s u t i l i z e d d i ets formulated to contain s p e c i f i c quantities of bluebunch wheatgrass and fescue (See Appendix C, Table 19-21). These species contained the greatest proportion of leafy material and were the f i r s t to begin vigorous growth. Previous year's growth was minimal due to the heavy snowpack (Table 2). The percentage of forbs and browse i n each d i e t varied throughout the year depending on 48 Diet Area Composition Percent Composition of Diet Ration 36-57 - Pelleted Ration* 100 Alpine Forage Kootenay Base Grass and Sedge** 80.81 Forbs 17.19 Browse 2.0 Winter Range B u l l River Grass 92.6 Forage Forbs 3.0 Browse 2.4 Winter Range Wigwam Grass 95.6 Forage Forbs 2.0 Browse 2.4 Winter Range Premier Ridge Grass 94 .0 Forage Forbs 4.0 Browse. 2.0 Winter Range Wigwam Grass 95.6 Forage Forbs 4.4 * See Appendix D f o r composition ** See Appendix C f o r species composition TABLE 19. A description of the composition of the die t s fed to the adult ewe group during 1968-69. 49 Date Forage Cut C o m p o s i t i o n o f D i e t * P e r c e n t Composi-t i o n o f D i e t A p r i l 15 - 20 G r a s s 99 F o r b s .5 Browse .5 May 10 - 15 G r a s s 90.9 F o r b s 8.2 Browse .9 May 15 - 25 G r a s s 94.7 F o r b s 0 Browse 5.3 J u l y 1 - 7 Grass 88.12 F o r b s 7.14 Browse 4.74 J u l y 1 0 - 2 0 and August G r a s s 88.1 1 0 - 2 0 F o r b s 7.2 Browse 4.7 S e p t . 15 - 20 G r a s s 90.0 F o r b s 7.0 Browse 3.0 * See A p p e n d i x C f o r s p e c i e s c o m p o s i t i o n TABLE 20. A d e s c r i p t i o n o f t h e c o m p o s i t i o n o f t h e w i n t e r range d i e t s f e d t o t h e c o n t r o l group d u r i n g 1969-70 and t o t h e e x p e r i m e n t a l group ( A p r i l -J u l y and O c t o b e r t o March) ( c u t on P r e m i e r R i d g e ) . 50 P e r c e n t Date C o m p o s i t i o n C o m p o s i t i o n Forage Cut A r e a o f D i e t o f D i e t O c t . 9 P r e m i e r Ridge G r a s s 95.0 F o r b s 4.0 Browse 1.0 O c t . 8 P r e m i e r R i d g e G r a s s 90.1 F o r b s 6.8 Browse 3.1 O c t . 20 - 25 Wigwam G r a s s 92.0 F o r b s 2.0 Browse 6.0 March 6 - 30 P r e m i e r Ridge G r a s s 95.0 F o r b s 2.0 Browse 3.0 TABLE 20. Cont. 51 Percent Date Composition Composition Forage Cut Area of Diet* of Diet June 10 -- 17 Kootenay Base Grass 31 .55 Subalpine Sedge 24 .55 Forbs 29 .56 Browse 14 .14 July 1 - 7 Kootenay Base Grass and Sedge 48 .98 Subalpine Forbs 40 .00 Browse 11 .02 Grass and Sedge 34 .35 Forbs 60 .85 Browse 4 .80 July 10 • - 15 Kootenay Base Grass 37 .45 Alpine Sedge 11 .84 Forbs 50 .71 Aug. 10 -- 20 Kootenay Base Grass and Sedge 45 .8 Alpine Forbs 35 .7 Grass 28 .9 Sedge 38 .1 Forbs 33 .0 Sept. 20 - 25 Kootenay Base Grass and Sedge 85 Alpine Forbs 15 * See Appendix C for species composition TABLE 21. The composition of the summer range diets fed to the experimental group during 1969. 52 seasonal a v a i l a b i l i t y and ease of c u t t i n g . S u f f i c i e n t forage was cut during October to feed both groups of sheep throughout the winter. These di e t s contained 90 to 95 percent grass (Table 20) but varied as to the species composition (See Appendix C). Thus, the d i e t fed during October and November contained approximately 50 percent bluebunch wheatgrass, that fed between December 4 and January 19 contained no bluebunch wheatgrass and that fed between January 20 and March 5 contained mainly Kentucky bluegrass. Overwintered grasses cut during March 1970, contained 50 percent bluebunch wheatgrass. The experimental group was placed on subalpine forage i n early June and digestion t r i a l s were conducted on subalpine and alpine mixtures from June u n t i l October. The composition of summer range forages i s presented i n Table 21. Subalpine forage contained more browse that alpine forage due to i t s r e l a t i v e a v a i l a b i l i t y . Grasses and sedges comprised 35 to 56 percent of the subalpine d i e t as compared to 45 to 85 percent of the alpine d i e t . Grasses and forbs were approximately equal in formulations of early cut diets from the summer range. During l a t e r cuts grasses comprised a larger percentage. During l a t e August and September forbs were s l i g h t l y d r i e r and more cured than grasses. In the alpine regions i t was d i f f i c u l t to f i n d large areas from which to cut s u f f i c i e n t forage for a preliminary and a digestion t r i a l period. In such cases two species 5 3 composition samples were taken i n order to describe the die t a r y mixture (See Appendix C). In l a te September,4 inches of snow and freezing b l i z z a r d s decreased the ease with which we could obtain forage. Cutting was s h i f t e d to a second alpine area where the grass was obtainable above the snow (See Appendix C, Table 21). Change i n Plant Nutrients during 1968 Preliminary work during the summer of 1968 indicated d e f i n i t e yearly changes i n crude protein and gross energy i n winter range plants. Differences between summer and winter range plants indicated s u f f i c i e n t p o t e n t i a l benefits to migrating animals to warrant a more extensive i n v e s t i g a t i o n i n 1969. Each value (Tables 22 and 23) was obtained using a sampling procedure producing a single subsample from the actual natural d i e t s fed during the digestion t r i a l s . They, thus, are not subject to tests for standard error or s i g -n i f i c a n c e s i m i l a r to those used for f i e l d sampling where several r e p l i c a t e s are tested f o r v a r i a t i o n . Forage was cut from June through August to show changes i n plant nutrients (Table 22) with time and maturity of the plants. A.sample cut i n June was 30 percent higher i n CP than two samples cut i n July from two winter ranges. The d i f f e r -ence i s masked by the presence of overwintered grass as shown previously i n Table 2. Date of Forage C o l l e c t i o n Feed Type Area Percent Crude Protein Gross Energy Kcal/gm Energy Content of Crude Protein Kcal Gross Energy Minus Crude Protein Fraction Kcal/gm June 6 Mainly Agropyron B u l l River Winter Range 7. 59 4.11 .43 3.89 July 24 II Wigwam Winter Range 5.87 4.31 .33 4.23 July 20 r i Premier Ridge Winter Range 4. 78 4.24 .27 4.16 August 5 Alpine Forage Kootenay Base Alpine Range 13.68 4.29 .77 4.08 Table 22. Crude protein and gross energy values with and without the energy contributed by the crude protein f r a c t i o n , i n winter and summer range forage cut i n 1968. 5 5 The a l p i n e sample c u t i n August c o n t a i n e d a p p r o x -i m a t e l y t w i c e as much c r u d e p r o t e i n as t h e J u l y j c u t w i n t e r range f o r a g e . T h i s sequence i n d i c a t e s t h a t c r u d e p r o t e i n d e c r e a s e s from s p r i n g t o f a l l i n w i n t e r range p l a n t s . A l p i n e f o r a g e u n d o u b t e d l y f o l l o w s a s i m i l a r t r e n d , b u t a p p r o x i m a t e l y 2 t o 3 months l a t e r , i n c o n f o r m i t y w i t h p h e n o l o g i c a l changes. The p r o t e i n c o n t e n t o f J u l y c u t f o r a g e i s s i m i l a r between y e a r s (compare T a b l e 22 t o 2 3 ) , w h i l e t h a t o f June' c u t f o r a g e i s l o w e r i n 1968 t h a n 1969, due m a i n l y t o t h e l a r g e amount o f p r e v i o u s y e a r ' s growth p r e s e n t i n a s t a n d i n g bunch d u r i n g 1968. The p r o t e i n c o n t e n t o f a l p i n e f o r a g e c u t i n A u gust o f b o t h y e a r s i s s i m i l a r ( T a b l e s 22 and 2 3 ) . Changes i n g r o s s energy ( T a b l e 22) f o r w i n t e r range p l a n t s appeared d i s s i m i l a r t o t h a t f o r c r u d e p r o t e i n . Gross energy i n c r e a s e d from June t o J u l y by .17 K cal/gm o r 4.1 p e r c e n t . The c y c l e i s d i r e c t l y comparable t o t h e change i n c a r b o h y d r a t e r o o t r e s e r v e s o f range p l a n t s shown by D o n a r t (1969). A more co m p l e t e e x p l a n a t i o n i s p r e s e n t e d i n t h e s e c t i o n on g r o s s energy f o r t h e a n n u a l c y c l e 1969. A l s o , t h e i n c r e a s e i n g r o s s energy may be due t o t h e d e c l i n e i n t h e p e r c e n t a g e o f p r e v i o u s y e a r s growth f r o m June t o J u l y . The g r o s s energy v a l u e o f a l p i n e f o r a g e was s l i g h t l y h i g h e r t h a n t h e average v a l u e f o r two J u l y c u t samples from t h e w i n t e r r a n g e . A t t h i s p o i n t i t i s r e a s o n a b l e t o assume 5 6 that a similar trend exists on both the summer and winter range. Therefore, migration can benefit animals i n terms of avai l a b l e energy, since high energy values occur i n alpine forage approximately three months l a t e r than i n winter range forage. A migrating animal can obtain high energy with high crude protein on the summer range but only high energy and low crude protein on the winter range, when measured i n the same month. The t o t a l gross energy determination was pa r t i t i o n e d so that the energy obtained from the crude protein f r a c t i o n could be removed (Table 22). This reduced the gross energy by about .45 Kcal/gm although the general trend was almost i d e n t i c a l . The major change occurred i n the alpine forage which declined from 4.29 to 4.08 Kcal/gm and f e l l below that for the winter range forage. The change i n the early summer growth from 4.11 to 3.89 Kcal/gm was also s i g n i f i c a n t . Crude protein to gross energy ratios w i l l be examined i n l a t e r sections. The r e l a t i o n s h i p between crude protein and gross energy content i s shown i n Figure 5 and i s described by the equation Y = 3.957 + .04191 x + 5.94. This r e l a t i o n s h i p i s s i g n i f i c a n t at the .05 l e v e l (p = .038). Conversely, when the energy content of the crude protein f r a c t i o n i s removed from the t o t a l gross energy the r e l a t i o n s h i p becomes inverse as shown i n Figure 6. I t i s described by the equation Y = 4.160 - .00619 x + 6.13. This r e l a t i o n s h i p i s not s i g n i f i c a n t at the .05 l e v e l (p = 1.0). Thus, the energy content of the GROSS ENERGY CONTENT IN KCAL / GM 58 CP f r a c t i o n has a d e f i n i t e a f f e c t on the slope of the l i n e and the s i g n i f i c a n c e of the r e l a t i o n s h i p . Seasonal Trends i n P l a n t N u t r i e n t s ' In 1969-70, p e r i o d i c sampling was undertaken to document the course of the change i n p r o t e i n and t o t a l energy values throughout a 12 month p e r i o d from i n i t i a t i o n of new growth i n A p r i l . I t can be seen t h a t the d e c l i n e i n crude p r o t e i n i s not c l o s e l y p a r a l l e l e d by the change i n gross energy (Table 23). Crude p r o t e i n . The annual c y c l e of crude p r o t e i n ( t o t a l n i t r o g e n x 6.25) i n range grasses has been documented by s e v e r a l workers: Watkins, 1943; Watkins .and - Knox, 1945; B l a i s d e l l et a l . 1952; McLean and T i s d a l e , 1960; Johnston and Bezeau, 1962; Harper, 1969. The r e s u l t s of s t u d i e s of d e c l i n e i n crude p r o t e i n through the annual c y c l e of the range grasses i s i l l u s t r a t e d i n Table 23 and F i g u r e 7 and are i n agreement wi t h the above authors. Crude p r o t e i n content of winter range grasses decreases from about 18 percent i n A p r i l to 2 percent the f o l l o w i n g March, p r i o r to new s p r i n g growth. The sample c o l l e c t e d on Premier Ridge on A p r i l 17 (Table 23), comprised the e a r l i e s t growth of bluebunch wheatgrass and rough fescue (about 2 to 4 inches i n h e i g h t ) . The p r o t e i n content was 20.78 and 15.00 percent, r e s p e c t i v e l y . The most r a p i d l o s s i n crude p r o t e i n occurred between A p r i l and J u l y (20 percent/month) w i t h a slower r a t e of d e c l i n e between J u l y Range Type Date of Forage C o l l e c t i o n Composition of Sample Percent Gross Crude Energy Protein Kcal/gm Energy Content of Crude Protein Kcal Gross Energy Minus Crude Protein Fraction Kcal/gm Winter A p r i l 5-10 A p r i l 15-20 May 10-15 May 15-25 July 1-7 July 10-20 Aug. 10-20 Sept.15-20 Oct. 9 Feb. 27 March 6-30 Agropyron spicatum Festuca s c a b r e l l a Agropyron-Festuca Mainly Agropyron* 20 15 14 11 10 7 5 5 3 3 3 2 .78 .00 .25 .20 .06 .15 .97 .16 .40 .22 .16 ;06 4. 4. 4. 4. 4. 4. 4. 4. 4. 4. 4. 4. 53 30 19 29 45 30 05 142 163 163 119 065 1.17 . 85 .81 .63 .57 .41 .34 .292 . 192 .182 .179 .116 24 05 94 12 31 19 ,94 06 11 11 07 03 Subalpine Alpine J u l y 1 - 7 July 10-15 August 10-20 Sept. 20-25 Nov. 4 May 18 Mixture * 16.01 17.25 12.91 11,59 9.19 7.00 4, 4 4 4, 4 4 47 42 424 396 588 546 .91 .97 .729 .655 .519 . 396 4, 4, 4, 4, 4, 4, 23 16 24 23 48 46 * See section on species composition of d i e t s . TABLE 23. The yearly change i n crude protein and gross energy with and without the energy contribution of the protein f r a c t i o n i n winter and summer range plants, 1969-70. FIGURE 7. The s e a s o n a l changes i n c r u d e p r o t e i n i n w i n t e r range p l a n t s f e d t o c a p t i v e sheep, 1969-70. 61 and September (17 p e r c e n t / m o n t h ) . T h e a c t u a l u n i t c h a n g e s i n c r u d e p r o t e i n c o n t e n t were 10.74 and 3.75 p e r c e n t r e s p e c t i v e l y . The t h r o u g h w i n t e r d e c l i n e amounted t o a n a c t u a l c hange o f 1.34 p e r c e n t b e t w e e n September and M a r c h (7 p e r c e n t / m o n t h ) . I t i s w e l l - k n o w n , h o w e v e r , t h a t g r a z i n g a n i m a l s f e e d s e l e c t i v e l y w h e r e as my s t a n d a r d f i e l d s a m p l e s were t a k e n somewhat r a n d o m l y . The v a l u e o f t h e d i f f e r e n c e b e t w e e n a s e l e c t i v e sample and a random s a m p l e i s r e f l e c t e d i n a s p e c i a l s ample c u t on November 25, c o n s i s t i n g e n t i r e l y o f t h e g r e e n l e a f t i p s o f b l u e b u n c h w h e a t g r a s s and f e s c u e . T h i s s a m p l e had a c r u d e p r o t e i n c o n t e n t o f 6.28 p e r c e n t , r o u g h l y t w i c e t h a t o f t h e random sample o f O c t o b e r (3.22 p e r c e n t ) w h i c h was s i m i l a r t o v a l u e s f o r November, p u b l i s h e d by B l a i s d e l l e t a l . 1952; McLean and T i s d a l e , 1960; D e m a r c h i , 1968. O b s e r v a -t i o n s on my tame b i g h o r n , w h i l e f r e e g r a z i n g , i n d i c a t e d t h a t i t was u n l i k e l y t h a t a b i g h o r n c o u l d o b t a i n 6.28 p e r c e n t c r u d e p r o t e i n w h i l e f e e d i n g on t h e a f o r e m e n t i o n e d s p e c i e s o f g r a s s . Some s e l e c t i o n was p o s s i b l e and e v i d e n t , h o w e v e r , and i t a p p e a r e d r e a s o n a b l e t o assume a v a l u e between 3.22 and 6.28 p e r c e n t c r u d e p r o t e i n f o r a w i l d g r a z i n g b i g h o r n s h e e p . The change f r o m O c t o b e r t o M a r c h i s so l i t t l e (1.16 p e r c e n t i n t h e b l u e b u n c h w h e a t g r a s s d i e t ) as t o be i n s i g n i f i -c a n t and p r o b a b l y r e f l e c t s t h e c o u r s e o f e v e n t s when t h e v e g e t a t i o n i s f r o z e n and r e l a t i v e s t a b i l i t y p r e v a i l s . T h e r e 62 was l i t t l e measurable e f f e c t n u t r i t i o n a l l y by t h i s change i n p r o t e i n , as w i l l be shown i n l a t e r s e c t i o n s . The g r e a t e s t change i n p l a n t p r o t e i n i s a t t r i b u t a b l e to advancing m a t u r i t y of the p l a n t , a s s o c i a t e d w i t h great increases i n crude f i b r e . Changes i n m a t u r i t y f o s t e r changes i n l e a f to stem r a t i o thereby producing l e s s l e a f m a t e r i a l i n a standing grass p l a n t w i t h season. Other f a c t o r s such as l e a c h i n g , dormancy, l e a f breakage and f r e e z i n g and thawing a l s o cause decreases i n p l a n t p r o t e i n (Watkins, 1943; McLean and T i s d a l e , 1960). The c a p t i v e sheep were maintained on winter range grasses cut i n October f o r the p e r i o d October - 1969 to March - 1970. During March and A p r i l , an overwintered d i e t of bluebunch wheatgrass was fed to the sheep. The c u t t i n g date, area and approximate species composition are described i n Table 20. This s e r i e s of t r i a l s was conducted i n order to assess the value of bluebunch wheatgrass as a d i e t a r y component. The n u t r i t i o n a l parameters of the f i e l d cut d i e t s fed during the winter v a r i e d depending upon the species mix i n d i f f e r e n t l o t s of feed. Thus, a d i e t c o n t a i n i n g 3.22 percent crude p r o t e i n was 50 percent bluebunch wheatgrass (fed i n October and November), another of 4.10 percent crude p r o t e i n contained no bluebunch wheatgrass (fed i n December to mid-January) . From mid January u n t i l March, the sheep were maintained on Kentucky bluegrass d i e t s c o n t a i n i n g an average 63 of 2.30 percent CP. A d i e t of overwintered bluebunch wheat-grass was cut and fed i n March and A p r i l and contained 2.06 percent CP. The a c t u a l d e c l i n e i n CP f o r d i e t s w i t h bluebunch wheatgrass was 1.16 percent from October u n t i l A p r i l w h i l e t h a t f o r the Kentucky bluegrass d i e t s was .52 percent from l a t e October u n t i l l a t e February. The c a p t i v e sheep were maintained on low p r o t e i n (natural) d i e t s which g r a d u a l l y d e c l i n e d i n CP from September u n t i l A p r i l . S i m i l a r l y , s e l e c t i v e g r a z i n g w i l d sheep must s u r v i v e on d i e t s d e c l i n i n g i n crude p r o t e i n throughout the w i n t e r . Animals w i n t e r i n g at 6000 to 7000 f e e t on south f a c i n g slopes of the Rockies i n November 1969 were feeding on the green leaves of grasses and sedges. Spring growth was observed on February 22, 197 0 on the Wigwam range and by March 15 on the Premier Ridge range, shortening the c r i t i c a l winter p e r i o d to approximately 3 to 3.5 months. The p e r i o d c a p t i v e animals were s u s t a i n e d on low q u a l i t y forage (5 months) represents an extended c r i t i c a l w i n t e r p e r i o d , not present i n the f i e l d d uring the w i n t e r of 1969-70 but evident i n previous w i n t e r s . The bluebunch wheatgrass d i e t cut i n October i s s l i g h t l y lower i n crude p r o t e i n than the d i e t of fescue, June grass, pinegrass and needlegrass. This i n d i c a t e s t h a t bluebunch wheatgrass i s of no p a r t i c u l a r d i e t a r y s i g n i f i c a n c e 64 i n the w i n t e r p r o t e i n n u t r i t i o n of a g r a z i n g u n g u l a t e . On the other hand, p h y s i c a l c h a r a c t e r i s t i c s making wheatgrasses a v a i l a b l e through most of the w i n t e r may not be p r e s e n t i n other g r a s s e s , thereby making them l e s s s u i t a b l e f o r w i n t e r g r a z i n g . A l s o , the n i t r o g e n p r o d u c t i o n per square meter may be g r e a t e r f o r stands of bluebunch wheatgrass than f o r other s p e c i e s . T h i s has been examined by Demarchi (1970). The crude p r o t e i n content of s u b a l p i n e and a l p i n e forage ( F i g . 8) shows a s i m i l a r t r e n d i n d e c l i n e from s p r i n g growth to f a l l dormancy or f r e e z i n g as t h a t f o r w i n t e r range f o r a g e . P r o t e i n content of s p r i n g growth on summer and w i n t e r ranges was approximately 17 p e r c e n t . Johnston e t a l . (1968) g i v e the p r o t e i n c o n t e n t o f s e v e r a l a l p i n e g r a s s e s and f o r b s of the a l p i n e tundra of A l b e r t a . T h e i r v a l u e s compare c l o s e l y t o those found i n t h i s study. The a l p i n e p l a n t s were c o l l e c t e d i n l a t e F a l l (cured stage) and c o n t a i n e d 5 t o 9 p e r c e n t p r o t e i n as they entered the w i n t e r . T h i s i s s i m i l a r t o the 9 percent v a l u e found i n t h i s study. In both s t u d i e s , the d e c l i n e i n crude p r o t e i n throughout the w i n t e r was minimal. During the s p r i n g p e r i o d on the w i n t e r range ( A p r i l through June) crude p r o t e i n d e c l i n e d 10 p e r c e n t i n 2.5 months. A s i m i l a r p e r i o d d u r i n g the s p r i n g growing season on a l p i n e ranges produced o n l y a 5.5 p e r c e n t d e c l i n e i n CP. The a l p i n e sample c o l l e c t e d on November 4 was encased i n i c e beneath 4 to 6 inches o f snow. The p r o t e i n content (9.2 percent) a t t h i s time i s r e l a t i v e l y h i g h and adequate 20 Q 19 LU 18 NG 17 RA 16 or 15 ME 14 UM 13 12 z 11 EIN 10 EIN t 9 O or 8 7 EP a 6 or o 5 1- 4 z UJ o 3 or UJ 2 Q. .11.25 16.61 .1^91 J1J59 .9.19 aug 15 sept 30 Tray may" 4 18 July 10 It DATE OF FORAGE COLLECTION FIGURE 8. The seasonal changes i n crude protein i n summer range plants fed to captive sheep, 1969--70. for animal growth. The sample taken i n May from beneath 3 feet of snow contained 7 percent protein and represents a 27 percent change in CP throughout the winter. By comparison, winter range forage declined 36 percent throughout the winter. I t i s believed that alpine plants are frozen before dormancy i n many years. The reduction i n protein loss from November u n t i l May, may represent preservation of protein by freezing and reduced leaching. The subalpine sample c o l l e c t e d on July 10 i s not the e a r l i e s t stage at which forage at t h i s elevation could be cut. During mid June, the protein content could range from 17 to 2 0 percent or higher. A migratory animal leaving the winter range i n June could improve i t s d i e t by 6 to 10 percent crude protein by moving on to subalpine ranges. An animal remaining on alpine ranges during November can obtain forage containing two to three times the protein found i n winter range grasses. These comparisons suggest the p o t e n t i a l advantage to the animal of migrating to alpine ranges as soon as new growth st a r t s on them i n the spring and of remaining on these ranges as l a t e as possible i n the autumn. Gross energy. The seasonal changes i n gross energy d i f f e r from that of other plant n u t r i e n t s . The changes are minor i n comparison with those of protein values and l i k e l y 67 i n s i g n i f i c a n t . As explained, the subsampling procedure from the natural diets did not allow appropriate s t a t i s t i c a l t e s t s . This cycle i n winter range and alpine range plants i s given i n Table 23 and described i n Figures 9 and 10. Gross energy declines from the e a r l i e s t spring growth on A p r i l 1-10 u n t i l mid May. I t increases from mid May u n t i l approximately June 15 and then declines to a minimum value the following March. The maximum to minimum decline i s .38 Kcal/gm or 8.85 percent. The high value i n June coincides with the early seed head stage and maximum l e a f development during active growth. Gross energy declines from June 15 u n t i l l a t e August and then increases during September and remains constant i n October. This increase may be the re s u l t of f a l l p r e c i p i t a t i o n and possible regrowth. Gross energy shows a t y p i c a l , gradual decrease throughout the winter months (.0 2 Kcal/gm/month). The s p e c i a l f i e l d sample c o l l e c t e d on November 5 had an elevated gross energy content (4.28 Kcal/gm) and i s .12 Kcal/gm or 3 percent greater than the October sample. I t was noted that the CP content of t h i s sample changed i n a p a r a l l e l manner. Donart (1969) showed a comparable cycle i n the carbohydrate reserves of two range grasses and t h i s probably explains the change i n gross energy content of the f o l i a g e of winter range grasses i n early spring. The high gross GROSS ENERGY INCLUDING PROTEIN GROSS ENERGY WITHOUT PROTEIN CONTRIBUTION DATE OF FORAGE COLLECTION FIGURE 9- The seasonal changes i n gross energy values of winter range plants, 1969-70, with and without the energy contribution made by the crude protein f r a c t i o n . — GROSS ENERGY INCLUDING PROTEIN GROSS ENERGY WITHOUT PROTEIN CONTRIBUTION DATE OF FORAGE COLLECTION FIGURE 10. The seasonal changes i n gross energy values of summer range plants, 1969-70, with and without the energy contribution made by the crude protein f r a c t i o n . 70 energy content o f f o l i a g e i n e a r l y A p r i l i s l i k e l y caused by d e p l e t i o n of r o o t r e s e r v e s as they move i n t o the f o l i a g e f o r . a c t i v e growth. The change i n c a l o r i c content may a l s o be a s s o c i a t e d w i t h a change i n com p o s i t i o n ( l i p i d versus s o l u b l e carbohydrate) w h i l e m a t e r i a l i s moving between the r o o t and the f o l i a g e . The d e c l i n e d u r i n g e a r l y May occurs when the f o l i a g e produces energy to r e b u i l d r o o t r e s e r v e s . The i n c r e a s e from May to June ( i n the f o l i a g e ) i n d i c a t e s t h a t r o o t r e s e r v e s are maximal and energy ( c e l l u l o s e and l i g n i n ) produced by p h o t o s y n t h e s i s i s remaining i n the f o l i a g e . Armstrong (1964) showed t h a t gross energy o f s e v e r a l p a s t u r e s p e c i e s d e c l i n e d w i t h m a t u r i t y . Values ranged from 4.5 to 4.7 Kcal/gm or s l i g h t l y h i g h e r than those i n t h i s s t u d y . Graham (1969) f e e l s t h a t g r o s s energy should be between 4.2 and 4.5 Kcal/gm f o r the normal d i e t s of ruminants. These v a l u e s are s i m i l a r to those achieved i n e a r l y growth winter range p l a n t s and a l l stages o f summer range growth. A sample c o l l e c t e d on A p r i l 17 had an average gross energy v a l u e of 4.42 Kcal/gm (Table 23). T h i s sample c o n s i s t e d of bluebunch wheatgrass (4.53 Kcal/gm) and rough fescue (4.30 Kcal/gm). The g r o s s energy c y c l e i n a l p i n e p l a n t s ( F i g . 10) d i f f e r s from the c y c l e shown i n winter range p l a n t s ( F i g . 7 ) . The h i g h v a l u e (4.47 Kcal/gm) i n s u b a l p i n e f o r a g e i s p r o b -a b l y due to advanced f o l i a g e development a f t e r r o o t r e s e r v e s have been r e b u i l t . There i s ver y l i t t l e change i n the 71 gross energy content of alpine forage between July 20 and the end of September. The depletion of root reserves, shown to occur in winter range plants, may have been missed i n alpine plants due to t h e i r rapid development. There i s a major increase i n gross energy from September 25 to November (4.40 to 4.60 Kcal/gm) when a frozen sample was c o l l e c t e d . There i s a s l i g h t decline during the winter, although gross energy of both the l a t e f a l l and early spring samples i s higher than a l l the other samples. The spring value i s not l i k e l y the lowest value to be achieved since spring melt and other degradative processes have not yet occurred. The p a r t i t i o n i n g of the t o t a l gross energy so that the portion contributed by crude protein (Table 23) could be removed i s compared to t o t a l gross energy for the winter range plants i n Figure 6 and the summer range plants i n Figure 10. The pa r t i t i o n e d energy for winter range plants p a r a l l e l s changes i n t o t a l energy but at a lower l e v e l . The greatest difference occurs when plant crude protein i s at i t s highest l e v e l . The comparison for alpine plants shows a similar trend (Fig. 10). The average gross energy value of alpine plants i s considerably higher than winter range plants throughout the year. The lack of f l u c t u a t i o n may be explained by the shorter growing season and the crowding together i n time of phenological stages. Gross energy reaches a high point i n winter range 72 f o r a g e a r o u n d J u n e 15 a n d i n a l p i n e f o r a g e a r o u n d A u g u s t 2 5 , two m o n t h s l a t e r . The d e l a y i n g r o w t h a n d a c c u m u l a t i o n o f g r o s s e n e r g y i n t h e l e a v e s o f a l p i n e p l a n t s a p p e a r s b e n e f i c i a l t o t h e e n e r g y n u t r i t i o n o f m i g r a t o r y a n i m a l s . The r e l a t i o n s h i p b e t w e e n c r u d e p r o t e i n a n d g r o s s  e n e r g y . The s e q u e n t i a l c h a n g e s i n c r u d e p r o t e i n a r e w e l l known a n d t h a t f o r g r o s s e n e r g y h a s b e e n p r e s e n t e d i n an e a r l i e r s e c t i o n . T h e s e two c o m p o n e n t s i n t h e w i n t e r r a n g e f o r a g e a r e r e l a t e d ( F i g . 11) ( A p p e n d i x D) a c c o r d i n g t o t h e c o r r e l a t i o n c o e f f i c i e n t R = .774 (p = .003) (Y = 4.06.4 + .09157 X + 5 . 8 7 ) . The r e l a t i o n s h i p l o s e s a l l s i g n i f i c a n c e when t h e e n e r g y c o n t r i b u t i o n o f t h e p r o t e i n f r a c t i o n h a s b e e n s e p a r a t e d ( F i g . 12) ( A p p e n d i x D ) . T h i s l a c k o f s i g n i f i -c a n c e i s shown by t h e r e g r e s s i o n (R = .250; p = 1.0) (Y = 4.057 + .00469 X + 5.87) . The g r e a t e s t d e p a r t u r e f r o m t h e s t r a i g h t l i n e r e l a t i o n s h i p o c c u r s i n J u n e d u r i n g p e a k e n e r g y c o n t e n t o f t h e f o r a g e w h i l e c r u d e p r o t e i n i s d e c r e a s i n g . The p r o t e i n t o e n e r g y r e l a t i o n s h i p i n t h e v e g e t a t i o n u s e d b y a g r o u p o f m i g r a t o r y s h e e p a s t h e y move f r o m t h e w i n t e r r a n g e a f t e r s p r i n g , g r o w t h i s c o m p l e t e ( l i n e X) , o n t o a l p i n e r a n g e w h e r e s p r i n g g r o w t h i s a c t i v e ( l i n e Y) a n d t h e n r e t u r n t o t h e w i n t e r r a n g e i n t h e autumn ( l i n e Z) i s shown 73 i n Figure 13 (Appendix D). The i n d i v i d u a l r e l a t i o n s h i p s are not s i g n i f i c a n t (R =-.925, p = > .1; R = .575; p = > .1; R = .934; p = .07) but have been used to describe the seasonal chain of events. Line "X" documents protein to energy r e l a t i o n s h i p s on the winter range as the plants mature and the root reserves (energy) are being replenished. Thus, crude protein declines while gross energy of the a e r i a l portions of the plant increase. Line "Y" depicts the s i t u a t i o n i n r a p i d l y growing alpine vegetation i n which the crude protein to gross energy content r e l a t i o n s h i p d i f f e r s from that of the winter range vegetation i n an equivalent phenological stage. By the time the snow forces the bighorn down onto the winter ranges i n autumn, vegetation i s dormant, dry and leached and the r e l a t i o n s h i p between protein and energy i s as represented i n l i n e "Z". The minimum values reached i n l a t e winter were 2.06 percent crude protein and 4.065 Kcal/gm gross energy. The o v e r a l l r e l a t i o n s h i p between these two v a r i a b l e s (Fig. 14) (Appendix D) during a yearly cycle i s s i g n i f i c a n t at the .01 l e v e l (R = .787 p = .0069) . In contrast, crude protein i s not s i g n i f i c a n t l y related to the p a r t i t i o n e d energy f r a c t i o n according to the c o r r e l a t i o n c o e f f i c i e n t (R = .172,p = 1.0) (Fig. 15 i n Appendix D) (Y = 4.12 + .0042 X + 5.74) . The actual crude protein to gross energy r a t i o s for 74 _ , , . crude Protein/ Date of Forage Composition Gross Energy Range Type C o l l e c t i o n of Sample Ratio Winter A p r i l 5-10 Agropyron-Festuca 4.05 A p r i l 15-20 " " 3.40 " May 10-15 Mainly Agropyron* 2.61 May 15-25 " " 2.26 " July 1-7 " " 1.66 July 10-20 " " 1.47 Aug. 10-20 " " 1.24 Sept. 15-20 ". " .81 Oct. 9 " -77 Feb. 27 " " .76 March 6-30 " " .51 Subalpine July 1 - 7 Mixture* 3.58 Alpine July 10-15 " 3.90 Aug. 10-20 " 2.92 Sept. 20-25 " 2.63 Nov. 4 " 2.00 May 18 " 1.54 * See section on species composition of d i e t s TABLE 24. The seasonal changes i n the crude protein to gross energy r a t i o for winter and summer range forages, 1969-70. winter and summer range forage are given i n Table 24 . Maximum r a t i o s were reached i n spring growth from both the winter and summer ranges but declined gradually throughout the summer and f a l l . The r a t i o for winter range forage p r i o r to migration was 3.08, 1.29 during the migratory period and .68 during the f a l l , a n d winter. In contrast, r a t i o s for summer range forage during the migratory period averaged 3.25. The decline i n r a t i o from early spring growth to over-wintered forage was 87.4 percent and 56.9 percent for winter and summer range forage, r e s p e c t i v e l y . The value i n c a l c u l a t i n g protein to energy r a t i o s l i e s i n i t s pr e d i c t i v e r e l a t i o n s h i p s . Seasonal changes i n forage phosphorus. The annual cycle of phosphorus i n native range plants has been reported by Watkins (1943) , Watkins and Knox (1945) , Johnston and Bezeau, (1962) and Johnston et al.(1968), Knox et a l . (1941). Most studies have described the phosphorus content f o r s p e c i f i c seasons without r e l a t i n g them to the annual cycle i n the plant species or of the range f l o r a available to a grazing animal. Monthly phosphorus values i n Table 25! serve to describe the annual cycle for some of the most important range species of the East Kootenay region of B r i t i s h Range Date of Forage Composition Total Percent Decline C o l l e c t i o n of Sample Phosphorus ppm. Between C o l l e c t i o n Periods Winter A p r i l 5 - 1 0 Agropyron spicatum Festuca s c a b r e l l a 2 2 0 0 2 8 0 0 " A p r i l 1 5 - 2 0 Agropyron-Festuca 2 6 0 0 1 9 . 2 " May 1 0 - 1 5 Mainly Agropyron* 2 1 0 0 9 . 5 " May 1 5 - 2 5 i i II 1 9 0 0 2 1 . 0 " July 1 0 - 2 0 M II 1 5 0 0 6 . 6 " August 1 0 - 2 0 II H 1 4 0 0 5 7 . 1 Sept. 1 5 - 2 0 II II 6 0 0 Oct. 9 8 0 0 Oct. 1 0 No Agropyron 6 0 0 " Oct. 1 5 •I II 8 0 0 Oct. 2 2 - 2 8 Poa pratensis 6 0 0 Feb. 2 7 Mainly Agropyron 5 0 0 March 6 - 3 0 H II 5 0 0 A p r i l ' 6 9 - March ' 7 0 = 8 1 . 0 Subalpine July 1 - 7 Mixture* 1 7 0 0 Alpine July 1 0 - 2 0 3 0 0 0 Alpine Aug. 1 0 - 2 0 n 3 0 0 0 Alpine Sept. 1 5 - 2 0 II 1 3 0 0 Alpine May 1 8 1 3 0 0 Max. to Min. = 5 6 . 6 * See section on species composition of d i e t s . TABLE 2 5 . The seasonal changes i n the phosphorus content of winter and summer range forages, 1 9 6 9 - 7 0 . Columbia. A comparison of the values obtained from the winter ranges and alpine summer ranges i s depicted i n Figure 16. The samples upon which these comparisons are made were taken monthly between A p r i l 1969 and March 1970. Maximum phosphorus values of winter range grasses, mainly bluebunch wheatgrass and rough fescue, reached 2600-2800 ppm. i n A p r i l but had declined to 1600 ppm. by early July. Decline was abrupt between July and September, with a t o t a l decline for the period of about 57 percent. Late winter values of 500 ppm. represented about an 81 percent loss from maximum values, the previous spring. Declines are minimal from early to late winter, during the period when forage i s frozen. The alpine range, with i t s l a t e r commencement of growth reached maximum level s toward the end of July (3000 ppm.) and maintained these throughout August. By freeze-up i n late September values had declined 56 percent to 1300 ppm. The May value represents the year-old growth as f i r s t exposed a f t e r snow melt i n the spring or as taken from beneath the snow cover. The much reduced decline during winter freeze-up i s comparable to that found on the winter range. In September, the phosphorus values of alpine vegetation are about twice those of the corresponding winter range forage and during late winter they are two to three times greater. — SUMMER RANGE PLANTS WINTER RANGE PLANTS ANNUAL REQUIREMENTS. FIGURE RANGE ADGT 10-20 DATE OF SAMPLING 16 THE ANNUAL CYCLE OF TOTAL PHOSPHORUS PLANTS, 1969-70. IN WINTER AND SUMMER 79 The phosphorus requirements of domestic sheep as l i s t e d by N.R.C. (1964) are .16 percent and .20 percent f o r gestation and l a c t a t i o n , r e s p e c t i v e l y . Watkins (1937; 43) suggest that .10 percent i s required for the winter main-tenance of range c a t t l e . As shown i n Figure 16 (annual requirements taken from N.R.C. and Watkins) spring cut winter range forage ( A p r i l 1 - June 15) provides adequate phosphorus during the l a s t 2.5 months of gestation. If the animals migrate to alpine ranges phosphorus needs are met during the l a c t a t i o n period. If they remain on the winter range throughout the summer phosphorus l e v e l s are below l a c t a t i o n requirements. For the is o l a t e d groups of sheep which remain on alpine ranges during the winter, phosphorus le v e l s appear adequate. For those that return to winter ranges, phosphorus l e v e l s i n winter range grasses drop below the winter maintenance l e v e l s described by Watkins (op. c i t ) . Also they are below the gestation requirements for the f i r s t 4 months of the gestation period. Animal T r i a l s Introduction. During the course of the study two methods were used to measure the influence of alpine forage on the n u t r i t i o n of bighorn sheep. Also, i t was important to determine the e f f e c t s of de c l i n i n g dietary q u a l i t y with season on the yearly n u t r i t i o n of t h i s species. 80 As mentioned, the annual d e c l i n e o f crude p r o t e i n i s w e l l documented and supported by the r e s u l t s of t h i s study. S i m i l a r , but l e s s dramatic d e c l i n e s of gross energy have been d e s c r i b e d , as w e l l as changes i n t o t a l phosphorus. A l l are r e l a t e d t o the seasonal p r o g r e s s i o n of p h e n o l o g i c a l stages. T r i a l s were conducted monthly d u r i n g 1969-70, u s i n g ' two groups of sheep. One group was maintained on w i n t e r range forage year around ( c o n t r o l ) w h i l e the o t h e r was a l t e r n a t e d between w i n t e r and summer range forage i n approx-imate synchrony w i t h the behaviour of w i l d b i g h o r n , i n o r d e r to measure the i n f l u e n c e of m i g r a t i o n ( e x p e r i m e n t a l ) . Both groups r e c e i v e d d i e t s d e c l i n i n g i n q u a l i t y as the annual c y c l e p r o g r e s s e d . During 1968, an i n s u f f i c i e n t number of animals prevented the use of two groups f o r comparative purposes. T h e r e f o r e , u s i n g a s i n g l e group, the e x p e r i m e n t a l d i e t s were arranged i n o r d e r o f d e c l i n i n g q u a l i t y u s i n g crude p r o t e i n as the g u i d e . T h i s served as an attempt t o s i m u l a t e the n a t u r a l c y c l e whereby animals r e c e i v e h i g h l y n u t r i t i o u s s p r i n g growth, then migrate to a l p i n e areas and subsequently r e t u r n to the w i n t e r range. Winter range forage c o l l e c t e d from e a r l y June u n t i l August d e s c r i b e d the n u t r i t i o n of a sedentary animal remaining on the w i n t e r range. A l p i n e forage served as a comparison f o r the m i g r a t o r y animal. R a t i o n 36-57 r e p r e s e n t e d the s p r i n g p e r i o d 81 p r i o r to migration. Low q u a l i t y diets cut i n l a t e July and containing 4 to 5 percent protein were given through-out the winter months. An experiment was conducted i n l a t e winter to determine the e f f e c t s of a s l i g h t dietary improve-ment, accompanied by a change i n species composition of the d i e t , on animals i n poor condition. The l a t t e r approach served to delineate guidelines (change i n forage nutrients, range of d i g e s t i b i l i t y , yearly changes i n body condition, the approximate influence of alpine vegetation, etc) which were used during the second year of the study i n order to more c l o s e l y simulate the natural cycle. Period of adjustment to the experimental d i e t s . The determination of d i g e s t i b i l i t y by the t o t a l c o l l e c t i o n method involves a preliminary period during which the animal adjusts to the d i e t . An inadequate adjustment period causes improper rumen adaptation and consequently d i g e s t i b i l i t y i s lowered. During 1968, the experimental d i e t s were fed i n descending order i n terms of q u a l i t y or the amount of nutrients they contained. Thus, the d i e t s d i f f e r e d i n form, qu a l i t y , p a l a t a b i l i t y and species composition. The data given in Figure 17 and 18-19 (Appendix G) indicate that an adjustment period of approximately 12 days i s necessary 82 to accommodate these die t a r y differences. Blaxter et a l . (1961) suggested that the period of adjustment as measured by maximal intake i s established at approximately 12 days. These experiements u t i l i z e d domestic sheep on a hay d i e t . During 1968, d a i l y intake measured-on an a i r - d r y basis, was used to e s t a b l i s h the period of maximal intake and subsequent adjustment. In each t r i a l feed intake increases u n t i l about the 12th day when i t begins to fluctuate around the average of a 7 day period taken a f t e r the 12th day. The sheep were changed from a high q u a l i t y p e l l e t e d r a t i o n (36-57) to a roughage r a t i o n of alpine forage (Fig. 17). Feed intake dropped markedly during the change and the i n i t i a l intake on alpine forage was only 300 to 350 grams per day. After 12 days dietary intake s t a b i l i z e d . The difference between i n i t i a l and maximal intake was 729 grams or 67.5 percent. The change from alpine to winter range forage (similar i n form but d e c l i n i n g i n q u a l i t y and d i f f e r i n g i n species composition) produced a subsequent drop i n feed intake. This decline was not as great as that experienced between the previous two d i e t s d i f f e r i n g i n form and q u a l i t y . The increase from I n i t i a l to maximal intake was 27 6 grams or 25 percent. >-< 1250 O "*"»» 1200 (/) s 1150 RA 1100 O 1050 z 1000 LU 950 < BOO Z 850 800 Q Ui LU 750 u_ 700 650 < 1- 600 z 3 550 _l 0 500 > UJ 450 0 400 < 350 UJ > 300 < 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 1ft 20 21 22 23 24 TIME IN DAYS FIGURE 17. The average d a i l y voluntary feed intake of alpine forage three adult ewes, using two day averages. 8 4 The change t o a l o w e r q u a l i t y w i n t e r range d i e t ( F i g . 1 9 ) , d i f f e r i n g o n l y i n q u a l i t y , produced v e r y l i t t l e d r o p i n f e e d i n t a k e d u r i n g t h e change. The d i f f e r e n c e between i n i t i a l and maximal f e e d i n t a k e was 163 grams o r 14 p e r c e n t . T h e r e f o r e , t h e s e d a t a i n d i c a t e t h a t a p p r o x i m a t e l y 12 days a r e needed t o a c h i e v e maximal i n t a k e and accompanying subsequent a d j u s t m e n t , i n d e p e n d e n t o f t h e t y p e o r q u a l i t y o f t h e d i e t . A l s o , l e s s f l u c t u a t i o n i n f e e d i n t a k e i s e n c o u n t e r e d when t h e d i e t s a r e s i m i l a r i n form, q u a l i t y and s p e c i e s c o m p o s i t i o n . I n a l l t r i a l s c o n d u c t e d , p r e l i m i n a r y p e r i o d s o f a t l e a s t 18 days were us e d . I n most c a s e s c o n s e c u t i v e t r i a l s u t i l i z e d s i m i l a r f o r a g e s so t h a t p r e l i m i n a r y and c o l l e c t i o n p e r i o d s were c o n t i n u o u s from one t r i a l t o t h e n e x t . A p p a r e n t d i g e s t i b i l i t y o f d r y m a t t e r . D i g e s t i b i l i t y o f d r y m a t t e r v a r i e s w i t h t h e n u t r i e n t q u a l i t y o f t h e f e e d and i s t h e r e f o r e r e l a t e d t o b o t h c r u d e p r o t e i n and g r o s s energy c o n t e n t o f t h e f o r a g e ( D i e t z e t a l . 1962; Bezeau and J o h n s t o n , 1962: C o r b e t t e t a l . . 1963). D i g e s t i b i l i t y changes t h r o u g h o u t t h e f a l l and w i n t e r , p a r a l l e l i n g changes i n d i e t a r y q u a l i t y (crude p r o t e i n ) as shown i n F i g u r e 20. An e x t r e m e l y h i g h d i g e s t i b i l i t y on r a t i o n 36-57 (see c o m p o s i t i o n i n Appendix F) (82.7 p e r c e n t ) may be 85 PERCENT CRUDE PROTEIN IN DIET FIGURE 20 . The change i n average apparent d i g e s t i b i l i t y f or three adult ewes i n r e l a t i o n to protein content of the d i e t . 86 associated with the form (concentrate) and high nutrient content i n balanced r a t i o s (protein to energy and calcium to phosphorus) of the r a t i o n . Th-3 change to alpine forage produced an 18 percent decline i n average d i g e s t i b i l i t y although crude protein declined only 6 percent. A change to June and July cut winter range forage gave comparative d i g e s t i b i l i t y figures for a sedentary animal. June cut forage containing 7.59 percent CP produced a further 12.6 percent decline i n d i g e s t i b i l i t y . This d i e t contained 6 percent less CP than the alpine forage fed previously. A further lowering of the protein content of winter range plants by 1.7 percent produced only a 2 percent decline i n d i g e s t i b i l i t y . The major decline i n d i g e s t i b i l i t y of winter range forage (12 percent) occurred when the CP.changed from 5.87 to 4.78 percent during l a t e winter. . A sharp increase i n the d i g e s t i b i l i t y of winter range forage (30 percent) occurred when CP increased by 1 percent from 4.78 to 5.87 (Appendix H) percent while gross energy remained r e l a t i v e l y stable. Also, the greatest v a r i a t i o n among in d i v i d u a l s i n apparent d i g e s t i b i l i t y occurred with the d i e t lowest i n crude protein and average d i g e s t i b i l i t y as shown by the standard errors of the l a t t e r three winter range diets ± .87, 9.7 and 1.47. The r e l a t i o n s h i p between crude protein content of 90.04. 87 30.0. B«0 10-0 ±E«0 14-0 IE'0 1B«0 20*0 CRUDE PROTEIN CONTENT IN PERCENT FIGURE 21 . The r e l a t i o n s h i p between crude protein content of the forage and the apparent d i g e s t i b i l i t y of dry matter for the diets fed the adult ewe group. 88 the forage and the apparent d i g e s t i b i l i t y of dry matter (Fig. 21) as described by the equation Y = 30.69 + 2.596 x ± 6.32. I t i s s i g n i f i c a n t at the .01 l e v e l (p = .0044). Voluntary feed intake. Changes in feed intake associated with changes i n the crude protein content of the d i e t for the adult ewe group are shown in Figure 22. The decline in crude protein content of the diets used to simulate the natural cycle was not p a r a l l e l e d by changes i n feed intake. Feed intake declined 7.5 percent when the d i e t was changed from rat i o n 36-57 to alpine forage. The maximum to minimum decline was 14 percent as crude protein declined from 20 to 5 percent. I t increased approximately 2 percent during the change from alpine to winter range forage. The increase i n feed intake with d e c l i n i n g crude protein content may.serve as a temporary and p a r t i a l compensation for reduced protein values. This has been examined by c a l c u l a t i n g protein intake per day and d i g e s t i b l e protein per day for the diets i n ques-t i o n . The r e s u l t s are shown in Table 26. As given in Table 2 6 protein intake declined between die t s as crude protein content of the d i e t s decreased, although feed intake increased (Fig. 22). S i m i l a r l y , the d i g e s t i b l e protein f r a c t i o n declined between d i e t s . Thus, Feed Protein Digestible Diet Intake Percent Intake Percent Protein Percent Gm/day Increase Gm/day Decline Gm/day Decline Alpine 978.58 133.85 81.33 44 53 Agropyron cut 982.64 74.57 38.01 June 6 2 21 45 Agropyron cut 998.18 58.58 20.53 July 24 TABLE 26. The decline i n protein intake and d i g e s t i b l e protein with changes i n d i e t . co vo 90 1070 1080 1050 1040 1030 1020 1010 1000 990 < 980 ct 9 7 0 £ 960 (/) 950 < 940 3 93° Z 920 UJ 910 <• 900 p 2 890 Q 8 8 0  111 U j 870 UJ 860 o < 850 UJ 840 < 830 820 810 800 105851 978.58 FIGURE 22. 1383 755 5?7 475 CRUDE PROTEIN CONTENT OFTHE FORAGE The average feed intake for three adult ewes while on diets cut during the summer of 1968. 91 i n c r e a s i n g feed i n t a k e d i d not adequately compensate f o r d e c l i n i n g dry matter d i g e s t i b i l i t y ( F i g . 20), p r o t e i n i n t a k e or d i g e s t i b l e p r o t e i n . At the end of t h i s sequence of feeding t r i a l s an improved d i e t (5.87 percent CP) was'fed (Appendix H). As shown, d i g e s t i b i l i t y increased markedly (30 p e r c e n t ) . Feed in t a k e d e c l i n e d a f u r t h e r 12 percent from the previous sequence. The reasons f o r t h i s are not apparent at t h i s time although B l a x t e r (1962), (pg. 287) suggests t h a t there may be s e v e r a l exceptions to the g e n e r a l i z a t i o n t h a t the i n t a k e of food v a r i e s w i t h i t s d i g e s t i b i l i t y . A l s o , there i s evidence t h a t apparent d i g e s t i b i l i t y i ncreases at lower l e v e l s of feeding ( B l a x t e r , op. c i t . pg. 193) (See s e c t i o n on feed i n t a k e d u r i n g 1969-70 of t h i s study). As shown p r e v i o u s l y , changes i n average d i g e s t i b i l i t y more c l o s e l y c o i n c i d e w i t h changes i n crude p r o t e i n content of the d i e t than does feed i n t a k e . The r e l a t i o n s h i p between d i g e s t i b i l i t y and feed i n t a k e i s shown i n F i g u r e 23. I t i s s i g n i f i c a n t at the .05 l e v e l according to the c o r r e l a t i o n c o e f f i c i e n t R = .887 ( p r o b a b i l i t y equals .045). A l s o , apparent d i g e s t i b i l i t y may be p r e d i c t e d from feed i n t a k e , according to the r e g r e s s i o n equation Y = - 222.0 + .284 x + 52.73. Thus, as d i g e s t i b i l i t y i n c r e a s e s by 1 percent the average feed i n t a k e per day i n c r e a s e s by only 3.50 grams. 92 FIGURE 23. The r e l a t i o n s h i p between feed Intake and apparent d i g e s t i b i l i t y for the adult ewe group. 93 Ingested protein. Accompanying the decrease i n crude protein content of the forage i s a steady decrease i n t o t a l protein intake as shown i n Figure 24. Ingested protein i s a product of crude protein of the forage and feed intake. The maximum decline i n crude protein of the forage during 1968-69 was 75.8 percent while that for ingested pro-t e i n was 79.2 percent. The greatest decline i n protein intake occurred during the change from r a t i o n 36-57 to alpine forage (36 percent) and from alpine to winter range forage (4 4 percent). Changes between winter range forages were accompanied by r e l a t i v e l y minor declines i n crude protein. Thus, the sheep ingested 44 percent more protein on alpine forage than on June cut winter range forage i n a s i m i l a r phenological stage and 56 percent more than July cut forage, i n a l a t e r growth stage. While on the p e l l e t e d r a t i o n containing 19.83 percent crude protein the ewes ingested 209.92 grams of protein/day. This i s s i m i l a r to r e s u l t s obtained by Hogan et a l . (1969) and Robinson and Forbes (1970) on domestic sheep of s i m i l a r body weight. Their sheep ingested 239-251 and 164-215 grams of protein per day while on rations containing 26 and 20-23 percent CP, res p e c t i v e l y . The r a t i o of ingested protein to crude protein content of the forage (Table 27) indicates the influence of forage protein as well as feed intake on protein intake. The 94 W 3 T m 759 -"187 4/78 CRUDE PROTEIN CONTENT OF THE FORAGE FIGURE 24- The absolute protein intake for three adult ewes while on forage cut during the summer of 19 68. 95 Crude Protein Content of the Forage Feed Type Ingested Protein Gm/day)/Crude Protein Content of the Forage 19.83 Ration 36-57 10.6 13.68 Alpine 9.7 7.59 Mainly Agropyron 9.8 5.87 H i t 9.9 4.78 •I i i 9.1 TABLE 27. The r a t i o of ingested protein to crude protein content of the forage, 1968-69. greatest intake of protein/unit of forage protein occurred on ra t i o n 36-57 according to the r a t i o of 10.6 The e f f i c i e n c y of protein ingestion (according to the ratio) declines to 9.7 during the change to alpine forage while crude protein changes from 19.83 to 13.68 percent. Under the influence of increasing feed intake e f f i c i e n c y increases according to the increase i n r a t i o (from 9.7 to 9.9) during the change from alpine to winter range forage. Forage protein declines to 5.87 percent at t h i s time. As both forage protein (4.78 percent) and feed intake decline the r a t i o (9.1) indicates the l e a s t e f f i c i e n t use of plant protein. During the experimental period i n A p r i l (Appendix H) a one percent increase i n feed protein over that of the previous d i e t (4.78 percent crude protein) provided a 4 gm/ day increase i n absolute ingested protein although the r a t i o declined to 8.0. The increase i n absolute protein intake i s not proportional to the change i n plant protein nor to the decline i n feed intake. The a b i l i t y to increase feed intake as a compensatory measure to maintain nutrient intake i s accompanied by an increase i n the e f f i c i e n t use of dietary protein but by a decrease i n the crude protein content of the feed as well as the actual amount of crude protein ingested. Apparent d i g e s t i b l e protein. The protein n u t r i t i o n of the captive bighorn ewes during 1968-69, i n the form of d i g e s t i b l e crude protein (DCP), i s described i n Figure 25. Crude protein of the feed and ingested protein have previously been shown to decline gradually throughout the year, s i m i l a r to that of DCP in Figure 25. According to Robinson and Forbes (1970) and Hungate (1966) , crude protein content of the d i e t a f f e c t s protein and dry matter d i g e s t i -b i l i t y , feed intake, microbial protein synthesis, and provides for the n u t r i t i o n of the f i b r e and starch digesting bacteria which ultimately leads to the n u t r i t i o n of the host i n the form of d i g e s t i b l e protein and energy. Apparent DCP declined from 174.09 grams per day while on p e l l e t e d r a t i o n 36-57 which contained about 20 percent 97 APPARENT DCP IN PERCENT APPARENT DCP IN G R A M S / DAY TJT83 13.68 75T~ 557 5 7 F CRUDE PROTEIN CONTENT OF THE DIET IN PERCENT FIGURE 25 . The change i n apparent d i g e s t i b l e p r o t e i n f o r the adult ewe group, with seasonally d e c l i n i n g d i e t a r y q u a l i t y . 98 crude protein to 0 grams per day i n l a t e winter, on a winter range r a t i o n which contained 4.7 8 percent crude protein. The o v e r a l l decline was 100 percent i n a period of 9 months. The zero value (actually negative (-2.72) by the formula T ingested protein - protein content of the feces = d i g e s t i b l e crude protein) obtained i n late winter indicates that more nitrogen was l o s t i n the feces than was ingested. The additional quantity l o s t was probably metabolic nitrogen. The change from p o s i t i v e to zero DCP values occurred i n March, a f t e r a period of 4 months on low q u a l i t y diets during which time the dietary crude protein content declined from 5.87 to 4.78 percent (Fig. 25). S i m i l a r l y , percent d i g e s t i b l e protein declined from 82.91 while on the high q u a l i t y r a t i o n 36-57 (20 percent CP) to 0(-4.19, according to the previous formula) i n l a t e winter while on low q u a l i t y r a t i o n (4.78 percent CP). The decline i s greater than that for dry matter d i g e s t i b i l i t y (see F i g . 20), e s p e c i a l l y during late winter. These data indicate that alpine forage (13.68 per-cent CP) provided 53 percent more d i g e s t i b l e protein than the corresponding winter range forage (7.59 percent CP). It produced a DCP value of 61 percent as compared to 51 percent for the winter range forage. The experiment i n early spring (Appendix H) u t i l i z e d 99 an improved d i e t containing 5.87 percent CP or approximately 1 percent more than the lowest q u a l i t y d i e t fed previously. This produced a large increase i n DCP (26.41 grams/day) and percent DCP (55.92 percent) s i m i l a r to that of dry matter d i g e s t i b i l i t y . This may indicate that the digestive capacity of the rumen was l i m i t e d by the low q u a l i t y diets and e s p e c i a l l y by lack of nitrogen. Nitrogen as a l i m i t i n g factor w i l l be examined i n a l a t e r section. Crude Protein Content of the Forage Feed Type Digestible Protein (Gm/7 daysj/Crude Pro-t e i n Content of the Forage  19.83 13.68 7.58 5.87 4.78 Ration 36-57. Alpine Mainly Agropyron 61.4 41.6 35.1 24.5 0 (-3.9) TABLE 28. The r a t i o of d i g e s t i b l e protein to crude protein content of the forage. I t was shown previously that the sheep increased t h e i r feed intake when placed on low q u a l i t y winter range forage in an apparent attempt to increase nutrient intake. The n e g l i g i b l e improvement i n nutrient intake was accompanied by a s l i g h t increase i n the proportion of protein ingested i n r e l a t i o n to the crude protein a v a i l a b l e i n the forage. 100 The apparent improvement i n e f f i c i e n c y i s l o s t when d i g e s t i b l e protein i s expressed as a r a t i o with CP of the forage. Thus, the r a t i o declines gradually (Table 28) corresponding to changes i n forage q u a l i t y . Although feed intake increased on the low q u a l i t y winter range forage, d i g e s t i b i l i t y declined, producing a decline i n e f f i c i e n c y of u t i l i z a t i o n of ingested protein. E f f i c i e n c y declined for the experimental improved d i e t (Appendix H) when ingested protein was expressed as a r a t i o with CP.Efficiency increased for thi s d i e t (31.7) when the DCP/CP r a t i o was examined. This p a r a l l e l s the decline i n feed intake and improvement i n dry matter d i g e s t i -b i l i t y noted e a r l i e r . Nitrogen balance. The i n i t i a l study, involving.the adult ewe group determined nitrogen retention using the d i e t s of d e c l i n i n g q u a l i t y (expressed as percent dietary crude protein). The decrease i n feed q u a l i t y coincided with season from September 1968 u n t i l A p r i l 1969. This allowed us to simulate the natural c y c l e , by feeding high q u a l i t y d i e t s i n the summer and f a l l and low q u a l i t y diets i n winter and early spring. The amount of nitrogen that i s retained i n the body i s measured by subtracting f e c a l and urine nitrogen losses from the quantity of ingested nitrogen. Nitrogen and protein 101 balance data are presented i n Table 29 and changes i n n i t r o -gen retention i l l u s t r a t e d i n Figure 26. Nitrogen retention i s also expressed as nitrogen retained per gram of nitrogen ingested, per kilogram of body weight and per kilogram of 75 body weight" as shown i n Table 30. Crude protein content of the forage declined seasonally and appeared to influence changes i n ingested and d i g e s t i b l e protein and therefore w i l l influence protein balance. Thus, a l l nitrogen and protein balance data i n t h i s section i s expressed against crude protein content of the d i e t and the seasonal period during which the d i e t was fed. Nitrogen retention declined sharply with changes i n crude protein content of the d i e t from September u n t i l January (Fig. 26). It decreased 46.3 percent when dietary q u a l i t y , as represented by crude protein, declined from 19.83 percent (ration 36-57) to 13.68 percent (alpine forage). A further decrease of 53.3 percent occurred during the change from alpine to winter range forage (7.59 percent CP) although both forage types were in the leaf stage. The winter range forage contained old growth from the previous year, a s i t u a t i o n not apparent i n alpine forage. A change to lower q u a l i t y winter range forage i n the seed-head stage, containing only 5.87 percent CP caused a 63.9 percent decline in nitrogen retention from the previous d i e t . Dietary Quality Expressed as Nitrogen Protein Percent Crude Seasonal Period Retention i n Grams Retention i n Grams Protein on Each Diet Per 7 day Period Per day Per 7 day period Per day 19.83 July 1-Sept. 11 96.91 13.84 608.07 86.87 13.68 Sept.12-Oct. 6 51.97 7.43 328 .80 46.97 7.59 Oct. 7-30 24 .33 3.47 160.44 22.92 5.87 Oct. 31-Jan. 11 8.80 1.25 56 .13 8.02 4.78 Jan. 12-March 4 - - - - ' 5.87 March 5-April 10 17.21 2.46 107.59 15.37 TABLE 29. A summary of nitrogen and protein balance as i t relates to season and dietary q u a l i t y expressed as percent crude protein, for the adult ewe group, 1968-69. 103 FIGURE 26 . Changes i n nitrogen retained i n r e l a t i o n to dietary q u a l i t y , for the adult ewes, 196 8-69. 104 In November, a f t e r e s t a b l i s h i n g the base l i n e for nitrogen retention on a forage providing 5.87 percent CP,. dietary q u a l i t y , using the crude protein content of the d i e t , as the q u a l i t y c r i t e r i a , was reduced to 4.78 percent and retained at t h i s point for about 2.5 months. Nitrogen balance data were not c a l c u l a t e d during t h i s period (January to March i n Table 29) because urine could not be c o l l e c t e d , due to low ambient temperatures. I t i s l i k e l y that nitrogen balance would have been strongly negative as i t had been previously shown that d i g e s t i b l e protein was negative during t h i s period (see F i g . 25). Dietary crude protein was then returned to 5.87 percent, (Appendix H) whereupon nitrogen retention increased 49.2 percent above that of the base l i n e . Nitrogen retained per gram of ingested nitrogen increased 66.6 percent (Table 30) and nitrogen retained per 75 kilogram body weight and per kilogram body weight* increased approximately 50 percent above that of the base l i n e . As shown on Table 30, dietary CP of the d i e t consumed October 31 to January 11 was approximately one t h i r d of that consumed between July 1 and September 11, producing a 69 percent difference in nitrogen retention per gram of ingested nitrogen. S i m i l a r l y , nitrogen retained per kilogram of body .75 weight and per kilogram of body weight declined approxi-mately 91 percent. Dietary Quality Expressed as Percent Crude Nitrogen Retained Per Gram of Ingested Nitrogen Retained Per Kilogram Body Nitrogen Retained Per Kilogram Body Protein Nitrogen Weight Weight -75 19.83 .42 .21 .59 13.68 .34 .112 .32 7.59 .29 .054 .15 5.87 .13 .019 .055 4.78 _ — _ TABLE 30. Nitrogen retained per gram of ingested nitrogen, per kilogram of body weight and per kilogram of body weight*75 i n r e l a t i o n to changes i n dietary q u a l i t y f o r the adult ewe group. o 106 The data i n t h i s section demonstrate conclusively that alpine forage containing 13.68 percent CP i s superior to winter range forage containing 7.59 percent CP when i n a s i m i l a r phenological stage. Thus, nitrogen retained was 53 percent higher on alpine forage and nitrogen retained per gram of nitrogen ingested, per kilogram of body weight and 75 per kilogram of body weight* were 14.7, 51.7 and 53 percent higher, respectively, than for the corresponding winter range forage. Ingested energy. E a r l i e r i t was noted that the amount of ingested protein declined i n r e l a t i o n to the l e v e l of crude protein i n the forage. S i m i l a r l y , ingested energy p a r a l l e l s changes -in gross energy content of the forage (Fig. 27). The change i n energy intake for the adult ewes i s s i m i l a r to that for feed intake (compare F i g . 27 to 22) but d i f f e r s from the gradual decrease shown by ingested protein or d i g e s t i b i l i t y . Energy intake i s greatest on the p e l l e t e d r a t i o n ; about 1000 Kcal/day higher than either the alpine or winter range d i e t s (Fig. 20). Energy intake on the alpine r a t i o n i s s i m i l a r to that of three winter range d i e t s fed i n l a t e f a l l and early winter. Gross energy values are also s i m i l a r except for the June 6 cut winter range forage which contains 107 5300 5200 5100 5000 4900 4800 4700 4600 4500 4400 4300 4200 4100 4O00 3900 3800 3700 3600 3500 3400 3300 3200 3100 3000 ,524a 29 4299.98 4027.91 FIGURE 27 4.95 323 4lT 4JI *2l GROSS ENERGY CONTENT OF THE FORAGE IN Kcal/gm The average d a i l y absolute energy intake for three adult ewes during 196 8-69. 108 Gross Energy-Content of the Forage Forage Type Ingested Energy (Kcal/day^/Gross Energy of the Forage (Kcal/gm) 4.95 Ration 36-57 1058.6 4.29 Alpine 978 .6 4.11 Mainly Agropyron 982.0 4.31 II H 997.6 4.24 i i II 949.9 TABLE 31. The r a t i o of ingested energy to gross energy of the forage during 1968-69. only 4.11 K cal/gm. The depletion of root reserves, p r i o r to the buildup of carbohydrates i n the a e r i a l portion of the plants (see the section on the annual cycle of gross energy) probably explains the low gross energy values at that time (4.11 K cal/gm) and subsequent low energy intake (4036.31 K cal/day) (Fig. 27). The e f f i c i e n c y of u t i l i z a t i o n of gross energy of the forage i s described by the r a t i o of ingested energy to gross energy content of the forage (Table 31). The r a t i o i s high-est for r a t i o n 36-57 (1058.6), declines by 80 units during the transfer to alpine forage and then begins to increase s l i g h t l y during the next two dietary changes on winter range forage. This increase i s s i m i l a r to that shown fo r feed . 1 0 9 i n t a k e and to t h a t of the ingested p r o t e i n to CP r a t i o d u r i n g the temporary compensatory p e r i o d explained p r e v i o u s l y . During the w i n t e r the r a t i o d e c l i n e s s h a r p l y as d i d t h a t f o r the corresponding p r o t e i n r a t i o , although gross energy of the forage remained r e l a t i v e l y constant. To t h i s p o i n t the compensatory e f f e c t has i n f l u e n c e d feed i n t a k e , the ingested p r o t e i n to CP r a t i o , energy i n t a k e and the ingested energy t o gross energy r a t i o . I t does not appear i n the DCP-CP r a t i o and w i l l be subsequently examined i n the d i g e s t i b l e energy to gross energy r a t i o . Apparent d i g e s t i b l e energy. A measurement of apparent d i g e s t i b l e energy (DE) serves to d e s c r i b e the r o l e of n a t u r a l winter and summer range forages as a source of energy duri n g an annual cycle.. Apparent DE i s de f i n e d as the d i f f e r e n c e between the heat of combustion of food ingested and the heat of combustion of m a t e r i a l excreted i n the feces. I t i s a measure of the apparent c a l o r i f i c value of the m a t e r i a l s absorbed from the gut. No attempt was made to determine metabolizable energy l o s s e s . Apparent DE i n t a k e s f o r the a d u l t ewe group and the gradual d e c l i n e are d e s c r i b e d i n F i g u r e 28. During the feeding p e r i o d , September 1968 t o March 1969, the ingested c a l o r i f i c and DE in t a k e d e c l i n e d i n r e l a t i o n to the gross energy content of the d i e t . The maximum t o minimum d e c l i n e of DE 110 _ DIGESTIBLE ENERGY IN 0 / o — DIGESTIBLE ENERGY - Kcal/day 495 429 ~4ll 43T*~ 424 GROSS ENERGY CONTENT OF DIET FED IN Kcal fcn FIGURE 28 • The change i n d i g e s t i b l e energy intake f o r three adult ewes with seasonally changing d i e t a r y q u a l i t y expressed as gross energy. I l l was 62 p e r c e n t . The ewes m a i n t a i n e d o n r a t i o n 36-57 d i g e s t e d a p p r o x i m a t e l y 4600 K c a l / d a y b u t a b s o r b e d a b o u t 44 p e r c e n t l e s s e n e r g y p e r d a y when c h a n g e d t o a l p i n e f o r a g e . The c h a n g e t o J u n e c u t w i n t e r r a n g e f o r a g e (4.11 K c a l / g m i n F i g u r e 28 r e s u l t e d i n a f u r t h e r d e c r e a s e o f DE o f 16 p e r -c e n t . T h u s , t h e DE i n t a k e ( K c a l / d a y ) a n d t h e p e r c e n t DE w e r e g r e a t e r f o r a l p i n e f o r a g e t h a n w i n t e r r a n g e f o r a g e w h i l e i n a s i m i l a r p h e n o l o g i c a l s t a g e . W h i l e on t h e l o w e s t q u a l i t y d i e t (4.78 p e r c e n t CP a n d 4.24 K c a l / g m ) ( a c c o r d i n g t o t h e CP c o n t e n t ) i n l a t e w i n t e r , DE d e c l i n e d t o 1740 K c a l / d a y a n d t h e p e r c e n t DE t o a b o u t 41 p e r c e n t . M a t u r e f o r a g e c u t d u r i n g J u l y ( 4 . 3 1 K c a l / g m ) c o n t a i n e d more g r o s s e n e r g y t h a n e i t h e r J u n e c u t f o r a g e (4.11 K c a l / g m ) o r a l p i n e f o r a g e (4.29 K c a l / g m ) . T h i s p r o d u c e d a s l i g h t i n c r e a s e i n b o t h t h e DE e n e r g y i n t a k e and p e r c e n t DE. I t a p p e a r s r e l a t e d t o t h e c o m p e n s a t o r y e f f e c t d e s c r i b e d e a r l i e r f o r o t h e r c o m p o n e n t s . A s s t a t e d i n an e a r l i e r s e c t i o n , t h e d i g e s t i v e c a p a c i t y o f t h e rumen a p p e a r s t o be r e d u c e d w h i l e on t h e l o w e s t q u a l i t y d i e t . T h e s e d a t a may i n d i c a t e t h a t g r o s s e n e r g y a s s u c h i s n o t l i m i t i n g p r o p e r rumen f u n c t i o n s i n c e g r o s s e n e r g y c h a n g e s w e r e r e l a t i v e l y m i n o r on t h e n a t u r a l d i e t s w h i l e DE c h a n g e d a b o u t 22 p e r c e n t . I t i s e n t i r e l y p o s s i b l e t h a t a v a i l a b l e e n e r g y i n t h e f o r m o f s o l u b l e c a r b o h y d r a t e i s l i m i t i n g . The p e r c e n t DE d e c l i n e d f r o m 88 t o 41 p e r c e n t d u r i n g 112 t h i s period, p a r a l l e l i n g changes i n dry matter d i g e s t i b i l i t y . Blaxter (1962) has shown that changes i n percent DE usually vary less than 1-3 percent with changes i n dry matter d i g e s t i b i l i t y . D igestible energy changes were s l i g h t (actual change = 4 7 percent) compared to the sharp decrease i n DCP (actual change = 87 percent) . The experimental period i n l a t e winter using the improved d i e t (Appendix H) produced an actual increase i n DE of 584.64 Kcal/day and one of 26.86 percent for the d i g e s t i -b i l i t y of energy. The magnitude of increase i s s i m i l a r to that for DCP and dry matter d i g e s t i b i l i t y (See Appendix H for comparison). These increases occurred during a dietary improvement of 1 percent crude protein and only .02 K c a l / gm gross energy. I t i s l i k e l y that the protein change i s more b e n e f i c i a l than the energy change. Gross Energy Digestible energy Content of (Kcal/day)/Gross energy the Forage Content of the For-(Kcal/gm) Feed Type age 4.9 5 Ration 36-57 930.9 4.29 Alpine 600.7 4.11 Mainly Agropyron 509.6 4.31 II II 519.3 4.24 II M 410.6 TABLE 32. The r a t i o of d i g e s t i b l e energy to gross energy content of the forage. 113 I t was shown e a r l i e r that feed intake and sub-sequently ingested energy increased s l i g h t l y during the change from alpine to winter range forage, as a com-pensatory measure. Also, the r a t i o of ingested energy per Kcal of plant energy showed a s l i g h t increase i n e f f i c i e n c y . When the d i g e s t i b i l i t y of energy i s considered, the r a t i o of DE to gross energy of the forage declines gradually (Table 32) from the highest to lowest q u a l i t y d i e t , with the exception of the Ju l y d i e t (4.31 Kcal/gm). Therefore, the compensatory e f f e c t shown by feed and nutrients at the ingested l e v e l i s reduced by the decline i n d i g e s t i b i l i t y and DE to gross energy r a t i o , s i m i l a r to that for the DCP r a t i o . The r a t i o for alpine forage i s higher than those obtained on winter range forage, i n d i c a t i n g that i t provides more DE per Kcal/gm of gross energy i n the forage. The r a t i o of d i g e s t i b l e protein to d i g e s t i b l e  energy. Singly, DCP and d i g e s t i b l e gross energy serve as p a r t i a l explanations of the year-long n u t r i t i o n of bighorn sheep. According to Wood and Cowan (1969), recent work fWood, 1964) suggests that data on the protein content of wild forages i s of li m i t e d value unless information on the availa b l e energy of such forages i s also recorded. I f either the l e v e l of d i g e s t i b l e energy or protein i s exces-sive the i n d i v i d u a l consuming the r a t i o n w i l l tend to grow slowly and w i l l y i e l d a carcass t h a t . i s high i n f a t or r e l a t i v e l y lean, r e s p e c t i v e l y . Any s e r i e s of gradations between extreme fatness or leanness can be achieved by manipulation of the protein to energy r a t i o . A r a t i o of d i g e s t i b l e protein to energy (Gm/Mcal) may serve to describe the o v e r a l l n u t r i t i o n of the animal in r e l a t i o n to general physical condition and weight gains at d i f f e r e n t points i n the yearly c y c l e . Preston (1966) suggested a r a t i o of 20.4 for maintenance of lambs and one of 22.4 for lambs gaining at the rate of .4 Kg/day. Robinson and Forbes (1970) achieved a r a t i o of 30.1 f o r optimum weight change i n lambs. The d i g e s t i b l e protein to energy r a t i o i s presented i n Table 33 for the adult ewes during 1968-69. The r a t i o varied between 37.8 and 0 (-3.1) on the highest and lowest q u a l i t y d i e t , r e s p e c t i v e l y . Only a few body weights were obtained for the adult ewes as they were highly excitable and extremely d i f f i c u l t to handle during the period they were i n c a p t i v i t y . The use of a r a t i o tends to minimize i n d i v i d u a l differences for d i g e s t i b i l i t y of n u t r i e n t s . The r a t i o was 37.8 and 30.6 on r a t i o n 36-57 and alpine forage, respectively. Both rations contained adequate quantities of protein and energy. The r a t i o of 18.2 for the June cut winter range forage i s also 115 Date Forage Description of Crude Protein Ratio of DP Collected the Diet Content i n Gm. to DE in M/cal — Ration 36-57 19.83 37 .8 August 5-10 Alpine Forage 13.68 30 .6 June 6 Mainly Agropyron 7 .59 18 .2 July 24 Mainly Agropyron 5.87 9 .2 July 20 Mainly Agropyron 4 .78 0 TABLE 33. The r a t i o of d i g e s t i b l e protein to d i g e s t i b l e energy for the adult ewe group while on di e t s changing i n nutrient content. 116 r e l a t i v e l y high. Crude protein has declined to 7.6 percent during the annual decline and gross energy has dropped to 4.11 K cal/gm during depletion of root reserves, producing a favourable r a t i o with a lower intake of nutrients. The change to July cut winter range forage caused a 50.5 percent decline i n the r a t i o . The decline i n the r a t i o arises from the continuing decline in crude protein along with an increase i n gross energy. Further declines i n crude protein and gross energy (July 20 cut forage i n Table 33) produced a second large decline i n the r a t i o to 0 (-3.1). The sheep were fed on these two lower q u a l i t y diets for about 4 months during the winter (Table 33). The greatest v a r i a t i o n among i n d i v i d u a l d i g e s t i b i l i t y of crude protein and gross energy occurred on the lowest q u a l i t y forage cut on July 20 (21 to 54 percent). During the experimental period i n e a r l y spring, (Appendix H), dietary protein was increased by 1 percent with only s l i g h t changes i n gross energy. This caused the r a t i o to increase to 11.35, s l i g h t l y higher than that achieved on an. e a r l i e r d i e t containing s i m i l a r quantities of nutrients (July 26 versus July 24 cut winter range forage). The r a t i o increased 14.45 units over the lowest q u a l i t y forage cut on July 20. Also, the lowest r a t i o of d i g e s t i b l e protein to d i g e s t i b l e energy i s associated with the lowest r a t i o of 117 0-0 0-5 LO 1-5 S-0 E-5 3-0 3-5 4-0 4-5 CRUDE PROTEIN TO GROSS ENERGY RATIO IN THE FORAGE FIGURE 29. The re l a t i o n s h i p between the d i g e s t i b l e protein to energy r a t i o and the crude protein to gross energy r a t i o during 1968-69 . 118 protein to energy i n the forage. As shown i n Figure 29 the pre d i c t i v e value of using the forage nutrient r a t i o to obtain the d i g e s t i b l e r a t i o i s very high. This r e l a t i o n -ship i s described by the equation Y =-8.73 + 12.1 x± 1.17 (P = .0032). The data in th i s section along with the r e s u l t s of the previous two sections provides evidence that crude protein rather than gross energy i s l i m i t i n g rumen function. The animals were lo s i n g weight during the period they were on July 20 cut forage and an index of physical condition showed them to be i n t h e i r poorest form. Fecal weights and protein l o s s . A measurement of the p o s i t i v e aspects of protein metabolism such as ingested,, d i g e s t i b l e and nitrogen balance necessitates an examination of the pathways through which protein i s l o s t . A summary of change i n f e c a l weight and f e c a l protein loss i s presented i n Table 34 and i l l u s t r a t e d i n Figures 3 0 and 32. The r e l a t i o n s h i p between f e c a l loss and the apparent d i g e s t i b i l i t y of dry matter i s given i n Figure 30. I t was explained previously that the diets were fed i n order of dec l i n i n g q u a l i t y , to simulate the natural cycle. This was shown to cause comparable declines i n d i g e s t i b i l i t y , ingested protein, etc. According to Figure 30 f e c a l weight increased (65.5 119 D e s c r i p t i o n F e c a l F e c a l of Weight P r o t e i n D i e t Grams/Day Grams/Day F e c a l P r o t e i n Grams of as a percent of Fe c a l Ingested P r o t e i n P r o t e i n Per Gram of Feces Ration 36-57 A l p i n e Forage Agropyron cut June 6 Agropyron cut J u l y 2 4 Agropyron cut J u l y 2 0 187.47 343.33 35.40 52.38 472.53 36.56 495.10 38.04 544.66 44.45 16 .86 39.13 49.03 64 .93 102.09 .18 .15 .077 .076 .081 TABLE 34. A summary of f e c a l l o s s and f e c a l p r o t e i n f o r the ad u l t ewe group, 1968-69. 120 56 54 52 ^50 ^48 X46 >44 Q42 2 38 5 36 °34 ^ 32 CO n n LU 30 a 28 u.26 °24 2^2 S22o LU 16| 14 FECAL WEIGHT APPARENT DIGESTIBILITY 82.7 544.7 38.2 J187.5 19.83 1X68" CRUDE 7.59 PROTEIN 5.87 4 CONTENT INO/o 78 85 80^ z 7 5 * LU fa £ 2 165^  Q 60 O >• 155 g oo 50 to LU o 145 Q Hog 35% 130 FIGURE 30. The change i n f e c a l weight i n r e l a t i o n to changes i n apparent d i g e s t i b i l i t y of the d i e t , arranged i n seasonal sequence for the adult ewe group. 121 500.0+ 450.0. 400.0.. 350.0. 300*0 i M UJ hi u. 250.0.. SOO.O 150.0 iOO.O. Y = 912.8 - 8.89. x + 15.71 + 35.0 40*0 45-0 50.0 55-0 S0«0 . 65.0 70»0 75-0 BO.O 65.0 APPARENT DIGESTIBILITY IN PERCENT FIGURE 31. The rel a t i o n s h i p between apparent d i g e s t i b i l i t y and weight of feces per day for the adult ewe group, 1968-69. 122 PROTEIN LOSS IN GRAMS FECAL PROTEIN AS A PERCENT OF INGESTED PROTEIN FIGURE 32. The quantity of protein l o s t i n the feces i n grams and as a percentage of ingested protein for the adult ewes, 1968-69. 123 percent) as dietary q u a l i t y (CP content) declined and changed inversely with changes i n apparent d i g e s t i b i l i t y of dry mat-t e r . This d i r e c t inverse r e l a t i o n s h i p i s only natural as f e c a l weight i s the undigested residue of the dry matter intake with the remainder being the digested portion. The proportionate inverse r e l a t i o n s h i p between f e c a l weight and apparent d i g e s t i b i l i t y given i n Figure 31 i s described by the equation Y = 912.8 - 8.89 x ± 15.71 (p = .0008). In t h i s equation f e c a l weight i s the dependent variable but for predi c t i v e purposes i t appears possible to determine the apparent d i g e s t i b i l i t y of a d i e t by measuring f e c a l weights. This a l l e v i a t e s the necessity of measuring feed intake (which i s often d i f f i c u l t on grass rations and during the winter months). The improvement i n feed q u a l i t y of the experimental d i e t (Appendix H) given to the animals in l a t e winter pro-duced a dramatic increase i n d i g e s t i b i l i t y with a corre-sponding decline i n f e c a l weight (52.9 percent). These data show that loss by the f e c a l route may account for 17 to 62 percent of the dry matter ingested Figure 30. This i n turn w i l l produce a great v a r i a t i o n i n the loss of nutrients as has been shown in the section on d i g e s t i b l e protein. Figure 32 indicates that f e c a l protein loss expressed i n absolute terms does not follow a s i m i l a r trend to that of crude protein of the feed or ingested protein. There i s 124 l i t t l e v a r i a t i o n i n absolute f e c a l protein loss from the highest to lowest q u a l i t y d i e t . When expressed as grams of protein l o s t as a percent of protein ingested, the l i n e p a r a l l e l s changes experienced by the previously described protein f r a c t i o n s and losses range between 17 and 100 percent for the respective d i e t s . Thus, the r a t i o increases as feed q u a l i t y declines, i n d i c a t i n g a loss i n e f f i c i e n c y of nitrogen conversion and absorption while on lower q u a l i t y d i e t s . When the r a t i o i s expressed as grams of f e c a l protein l o s t per gram of feces (Table 34) the r e l a t i o n s h i p i s opposite to that expressed as protein l o s t as a percent of protein ingested. I t implies that the concentration of pro-t e i n i n the feces i s highest on the best q u a l i t y d i e t but declines as feed q u a l i t y declines. Although f e c a l protein i s highly concentrated on the high q u a l i t y r a t i o n (Table 34), less protein i s l o s t by the f e c a l route (35.4 gm/day) than when the sheep were on lower q u a l i t y feeds (3 6-52 gm/day) with the exception of the experimentally improved d i e t of Kentucky bluegrass (Appendix H). In the l a t t e r case, feed intake declined while apparent d i g e s t i b i l i t y increased sharply, producing a drop i n f e c a l protein loss (20.82 gm/ day) . Changes i n urine volume and protein content of the urine. Changes i n urine volume recorded during 1968-69 for 125 Urine Total Urinary Description Volume Protein Percent of Diet ml/day Grams/Day Protein i n Urine Ration 36-57 1317.4 87.22 6.37 Alpine Forage 540.1 34.36 6 .62 Agropyron Cut June 6 158.6 10.93 8.02 Agropyron Cut 157.0 12.61 8.48 July 2 4 TABLE 35. The change i n urine volume and loss of protein i n the urine during 1968-69, while on forage d e c l i n i n g i n q u a l i t y . 126 the adult ewe group are shown i n Table 35 and i l l u s t r a t e d In Figure 33. As dietary q u a l i t y (CP content of the forage) declined throughout the year, i t was accompanied by com-parable changes i n the urine volume, water intake (Fig. 33) and protein content of the urine (Fig. 35) (urine N was converted to urine protein for purposes of comparison). Also, energy content of the d i e t was shown to be s i g -n i f i c a n t l y related to water intake (See Fig.124). Changes i n urine volume are also associated with voluntary water intake (Fig. 34). During my t e s t s , urine volume declined by 58 percent as dietary q u a l i t y decreased (change from r a t i o n 36-57 to alpine forage) and a further 70.8 percent when the d i e t was changed to winter range forage (Table 35). While on winter range forage from October u n t i l December, changes i n urine volume were minimal (Fig. 33). Urine volume was not recorded during December to March due to low ambient temperatures. During the experimental period on the improved d i e t (Appendix H) urine volume increased to 570.6 ml. or 72 percent above the base l i n e established e a r l i e r i n the year for a d i e t of s i m i l a r q u a l i t y . The changes i n urine volume, as stated above, are associated with declines i n water intake of 42 and 48 percent respectively. The r e l a t i o n s h i p between urine volume and water intake i s given i n Figure 34. I t i s s i g n i f i c a n t according to 127 — — ESTIMATED CHANGE IN URINE VOLUME 5.21 3.03 1.61 1.71 1.40 WATER INTAKE IN L ITRES/DAY FIGURE 33. The change i n u r i n e volume d u r i n g the f a l l and w i n t e r o f 1968-69, w h i l e on d i e t s d e c l i n i n g i n q u a l i t y . 128 1400-0. 1300.01 I E O O . O . 1100.0.. 1000.0.. <j 300»0.. \ ni eoo-oj. 21 M 2 7C0.0.. s! ^600.0.. n s 500.0.. 400.0.. 300.0.. 500.0. 100.0. O'O 0.5 FIGURE 34 . - 275.7 + 302.9 x + 1.49 H 1 1 1 1 + + L O 1-5 2.0 E.5 3.0 3*5 4.0 4.5 5»0 5.5 G-0 WATER INTAKE IN LITRES / DAY The r e l a t i o n s h i p between urine volume and water intake during 1968-69. : 129 1743 8U "—383 2 0 . 5 2 6 4 APPARENT DIGESTIBLE PROTEIN INTAKE-GRAMS/DAY FIGURE 35 . The change in average percent protein and t o t a l protein i n the urine for three adult ewes i n r e l a t i o n to changes i n d i e t , 1968-69. 130 the c o r r e l a t i o n c o e f f i c i e n t R = .959 (probability = .0097), Thus, urine volume may be predicted from the equation Y = -275.7 + 302.9 x + 1.49. Reductions i n dietary q u a l i t y were also associated with declines i n absolute protein content of the urine as shown i n Figure 35. Thus urine protein declined by 60.7 per-cent ( p a r a l l e l to N intake) as the d i e t was changed from ra t i o n 36-57 to alpine forage and a further 65 percent when changed to winter range forage. Dietary q u a l i t y as shown by d i g e s t i b l e protein (Fig. 35) declined 53.3 and 64 percent, respectively, while protein intake dropped 34.7 and 50.2 per-cent during the above changes i n urine protein. The change to a second low q u a l i t y winter range forage produced l i t t l e change i n urine protein l o s s . Also the change to the improved d i e t i n March and A p r i l (Appendix H and F i g . 35) caused l i t t l e change i n absolute urine protein l o s s . I t appears that urine protein loss i s s t a b i l i z e d at 11-13 gm/day on diets below 6-7 percent CP. A comparison of Figures 33 and 35 indicates that urine volume and absolute protein content of the urine decreased simultaneously, with changes i n dietary q u a l i t y , with the exception of the t r i a l on the improved d i e t . In contrast, percent protein i n the urine tends to increase during t h i s period. Thus, protein concentration i n the urine changes inversely with urine volume. During the experimental period (Appendix H) percent protein i n the urine declined sharply (4.72) as urine volume increased 131 (570.6 ml) si m i l a r to the r e l a t i o n s h i p described i n the previous statement. During the experimental period on the improved d i e t (Appendix H), urine volume increased greatly and protein concentration decreased, producing only a s l i g h t change i n absolute protein l o s s . A comparison of protein loss by the f e c a l and urinary  pathways. A l t i t u d i n a l migration improves the n u t r i t i o n a l status of an animal through increased feed and nutrient intake, improved d i g e s t i b i l i t y , succulence and p a l a t a b i l i t y . I f these benefits are to be maintained throughout the c r i t i c a l winter period nutrient loss should be reduced.. In t h i s regard the pathways of protein loss ( f e c a l and urinary) were examined (Table 36) to determine i f eithe r p h y s i o l o g i c a l process (digestion or urinary function) enhanced nutrient retention during times of s t r e s s . Absolute f e c a l protein (Fig. 36) remains r e l a t i v e l y stable as dietary protein declines from 20 to 5 percent crude protein. Therefore, f e c a l protein i s r e l a t i v e l y low in comparison to protein intake when migratory animals subsist on summer range feed, 'but r e l a t i v e l y high when on winter range feed. The e f f i c i e n c y of the f e c a l pathway as an aid to protein retention i s thereby reduced during the winter months. Description of the Diet T o t a l Ingested F e c a l Fecal P r o t e i n Urine Urine Protein Urine Pr o t e i n P r o t e i n P r o t e i n Protein as a Percent of Protein as a Percent of as a Percent of Loss Grams/Day Grams/Day Ingested Protein Grams/Day Ingested Protein D P gm/Day Ration 36-57 209.92 35.40 Alpine Forage 133.85 52.38 Cut August 5 16.86 39.13 87.22 34.36 41.55 25.67 49.99 42.25 122.62 86.74 Agropyron Cut June 6 74.57 36.56 49.03 10.93 14.65 28.76 47.49 Agropyron Cut Jul y 24 58.58 38.04 64.93 12.61 21.50 6 1 . 4 2 50.65 Agropyron Cut J u l y 20 43.54 44.45 102.09 55.45 Est. TABLE 36. A comparison of p r o t e i n l o s s by the f e c a l and urinary pathways i n r e l a t i o n to d e c l i n i n g d i e t a r y q u a l i t y during 1968-69, as shown by ingested p r o t e i n . OJ 133 210 190 UJ 6 170 01 150 130 110 O z < 90 70 50 30 10 — INGESTED PROTEIN -* FECAL - U R I N A R Y " !§M 13.W ~T5§ 5.87 CRUDE PROTEIN CONTENT OF THE DIET IN 4JK PERCENT "5707 FIGURE 36. Absolute protein losses i n r e l a t i o n to ingested protein and crude protein content of the d i e t during 1968-69, arranged i n seasonal sequence. 134 In contrast, absolute urinary protein loss p a r a l l e l e d declines in ingested and d i g e s t i b l e protein. When feed p r o t e i n ranged between 5.87 and 7.59 percent CP, for a period of 5.5 months during the winter, urine protein losses were minimal, ranging between 11 and 12.6 grams/day (Fig. 36). By comparison, during l a t e winter f e c a l protein losses were 71.4 percent greater than urinary protein losses while e a r l i e r , on high q u a l i t y forage (ration 36-57) and summer range forage) they were 2 8 percent lower. Protein loss expressed as a percent of ingested and di g e s t i b l e protein i s given i n Table 36 and i l l u s t r a t e d i n Figure 37. They are shown i n r e l a t i o n to d e c l i n i n g dietary q u a l i t y as expressed as grams of ingested protein per day. Fecal protein loss increased from about 16 percent of ingested protein on the high q u a l i t y d i e t to about 102 percent on the low qu a l i t y d i e t when metabolic protein contributes almost e n t i r e l y to the f e c a l protein. In contrast, urinary protein losses expressed as a percentage of ingested protein decline while CP of the higher q u a l i t y rations changes from 19.83 to 7.59 percent and ingested protein declines from 210 to 74.5 grams/day (Fig. 37). Similar declines in urinary protein loss were noted when expressed as a percentage of d i g e s t i b l e protein. When ingested protein f e l l below 74 grams/day and CP of the forage below 7.6 percent, the r a t i o of urinary protein to ingested and d i g e s t i b l e protein began to increase, as shown i n Figure 37. This i s due mainly to the decline i n 135 FECAL PROTEIN AS A PERCENT OF INGESTED PROTEIN "•URINARY " II II II DIGESTIBLE ' 209^  1333 74J6 58J6 4T6 ABSOLUTE PROTEIN I N T A K E / D A Y Protein l o s t i n the feces and urine as a percent of ingested protein and urinary protein as a percent of di g e s t i b l e protein for the adult ewe group during 196 8-69. 136 the ingested and d i g e s t i b l e protein f r a c t i o n since absolute urinary protein loss remains r e l a t i v e l y stable during t h i s period. I t i s not a r e a l increase in urinary protein. It appears then, that the f e c a l pathway accounts for the major portion of protein l o s t from the body when low qual i t y forage tends to retard d i g e s t i b i l i t y . On the other hand, the urinary pathway tends to counterbalance the high f e c a l loss on low q u a l i t y d i e t s by maintaining a r e l a t i v e l y low l e v e l of protein loss. Thus, urinary losses become mini-mal when ingested protein i s around 74 grams/day and crude protein of the forage about 7 percent. A measure of t o t a l protein loss (Table 3 6) indicates that protein l o s t from the body tends to decline with forage qu a l i t y . I t appears to s t a b i l i z e at about 50 gm/day on diets containing l e s s than 7 percent CP. Fecal energy losses. I t has been shown previously that f e c a l protein losses account for 16 to 100 percent of the ingested protein. In comparison, dry matter losses by the f e c a l route ranged from 17 to 62 percent. Loss of energy by the f e c a l route i s i l l u s t r a t e d i n Figure 38 i n terms of absolute energy loss and as a percentage of ingested energy. Loss of energy ranged from 632 to 2287 Kcal/day while the adult ewe group was on the highest and lowest q u a l i t y d i e t s , r e s p e c t i v e l y . Fecal energy changes inversely to ingested energy (Fig. 38) and to d i g e s t i b i l i t y of dry matter, as well as to changes i n the various protein f r a c t i o n s . 137 24 23 22 21 £ 20 § 19 g 18 i >-K 15 17 16 14 13 12 11 10 9 8| - A B S O L U T E FECAL ENERGY — —FECAL ENERGY AS A PERCENT OF INGESTED ENERGY > 5 6 . 8 / / 48.1 47.9 / 2287-0 5631.9 5240.3 58 [56 54 52 50> 48 a U J 46 Z UJ 42 40 2 38 1 36 u. 34 O 32 t; 30 S 28 £ 26 £ L 24 < 22 < 20 >" 118 £ 16 Lu 14 -» < 12 O UJ 10 u" 8 6 FIGURE 38 4198.1 4036.3 4299.9 4027.9 INGESTED ENERGY-Kcal/DAY The change i n f e c a l energy associated with declining energy intake for the adult ewes during 1968-69, arranged i n seasonal sequence. 138 S i m i l a r l y , the f e c a l to ingested energy r a t i o declines with changes i n dietary q u a l i t y . I t ranges from 12 to 57 percent on the highest and lowest q u a l i t y d i e t , r e s p e c t i v e l y . Changes are s i m i l a r to that experienced by dry matter d i g e s t i b i l i t y but considerably less than that encountered with protein l o s s . On the lowest q u a l i t y d i e t fed i n late winter 100 percent of the ingested protein i s found i n the feces whereas only 57 percent of the ingested energy i s l o s t by the f e c a l route. Feed intake r e l a t i o n s h i p s . I t has previously, been shown by several authors that feed intake i s p a r t l y deter-mined by the nutrient content of the forage. The r e l a t i o n -ship between feed intake and nutrient content of the forage, d i g e s t i b l e nutrient f r a c t i o n s and the protein to energy r a t i o i s shown in Figures 3 9 through 44 i n Appendix G. These rela t i o n s h i p s served as a preliminary estimate of the range of feed intake and plant nutrients to be used during the experimental period i n 1969-70. The range of feed intake while on the experimental d i e t s was approximately 915 to 1057 grams/day. This appears narrow i n comparison to d i g e s t i b i l i t y (38 to 83 percent), crude protein content of the forage (5 to 20 percent) and gross energy content of the forage (4.1 to 4.95 K cal/gm). At t h i s point i t i s not s i g n i f i c a n t that the majority of r e l a t i o n s h i p s show low l e v e l s of c o r r e l a t i o n . This i s due to the r e l a t i v e l y low number of digestion t r i a l s c a r r i e d 139 out under t h i s feeding regime. The s i g n i f i c a n t r e l a t i o n s h i p between feed intake and ingested energy occurred because energy intake i s dependent upon feed intake which i n turn can be shown to be dependent on crude protein content of the forage. Estimation of the l i m i t i n g n utrient. According to Crampton (1964) and Preston (1966) a r a t i o of approximately 20:1 (DP i n gm to DE i n megcal) i s required f o r maintenance of domestic sheep. The established r a t i o given above, included NH3 absorption but made no allowance for a d d i t i o n a l protein formed from recycled nitrogen (Purser, 1970) . Thus, t h i s r a t i o means that 20 grams of DP i s required for each 1000 Kcal of DE consumed at maintenance. The r a t i o can be used i n t h i s study to estimate whether protein or energy becomes l i m i t i n g in l a t e f a l l and winter. According to Table .37 the actual DP consumed i s above the estimated r a t i o of 20:1 on r a t i o n 36-57 and alpine forage. I t i s only s l i g h t l y below the r a t i o (1.8 gm) when on June 6 cut winter range forage i n r e l a t i o n to the energy content of that p a r t i c u l a r r a t i o n . This r a t i o n contained 7.59 percent CP. The three winter range rations cut i n July supplied i n s u f f i c i e n t DP according to the amount of DE the sheep consumed. Thus, the rat i o n cut July 24 provided 20.53 grams of DP but required 4 4.80 grams to meet the 20:1 standard (a difference of 54.1 percent). The forage cut on July 20 was fed throughout the winter. DP became negative as Description of Feed Type Actual DP Consumed Per Day in Gm. Actual DE Consumed Per Day in meg.cal Actual DP Consumed per meg. c a l DE Estimated DP Required for The Actual DE Intake Ration 36-57 Alpine Mainly Agropyron cut June 6 Mainly Agropyron cut July 24 Mainly Agropyron cut July 20 Mainly Poa pvatensis cut July 26 174.09 81.33. 38 .01 20.53 -2.72 26.41 4.61 2.64 2.09 2.24 1.41 2.33 37.7 30.8 18.2 9.1 11.3 92.20 52.80 41.80 44 .80 28.20 46 .66 Table 37. The actual and estimated d i g e s t i b l e protein i n r e l a t i o n to the d i g e s t i b l e energy intake while the adult ewe group was on natural forages, 1968-69. o 141 metabolic protein contributed almost e n t i r e l y to protein l o s s . The sheep required about 28 grams/day d i g e s t i b l e protein according to the quantity of DE consumed. In early spring (1969) the protein content of the d i e t was increased 1 percent bringing i t to 5.87 percent CP (Appendix E ) . This allowed the sheep to consume 26.41 grams/day (DP) whereas they required 4 6.60 grams/day i n r e l a t i o n to the DE consumed, i n order to achieve Crampton 1s standard. I t appears that winter range forage does not provide adequate nitrogen i n r e l a t i o n to the amount of DE i t can supply during the c r i t i c a l winter period. Thus, nitrogen metabolism i s greatly hindered and consequently the diges t i v e capacity of the rumen i s reduced. According to HoLson (1969), "Consideration of a l l r e s u l t s suggests that the concentration of nitrogen i n the feed may be governing the concentration and so the diges t i v e a c t i v i t i e s of the rumen micro-organisms i n the winter months and t h i s i s the basis of our p i l o t experiment on provision of cheap urea blocks as a deer winter-feed supplement." My experimental period showed that a 1 percent increase i n CP of the forage could reduce the difference between the actual and estimated DP consumed from about 102 percent to 43.3 percent. 142 Simulated A l t i t u d i n a l Migration ' Sequence of feeding. During the second year of the study, digestion t r i a l data were c o l l e c t e d for the two groups of sheep from A p r i l 1969 to A p r i l 1970 (see page 5). This was subsequently divided into three subperiods: premigratory, migratory, postmigratory. During the i n i t i a l period both groups were fed spring growth forage from the winter range. The re s u l t s were averaged f o r a l l animals and presented as that for a single group (see F i g . 47 and Table 35 as examples). In the migratory period the experimental group was given subalpine and alpine forage while the control group subsisted s o l e l y on winter range forage. Both groups were given winter range forage during the f a l l and winter (postmigratory) to complete the annual cycle. Actual and calculated body weights. For the control group, the actual and calculated body weights obtained through-out the year were s i m i l a r (Fig. 45). Monthly weight increased gradually from early spring u n t i l l a t e summer (6 months). This would indicate that the d i e t , feeding regime and procedure used during and between t r i a l s would c l o s e l y approximate the s i t u a t i o n of wild sheep on the winter range year-round. By comparison, the actual and calculated weights for the experimental and control groups (Fig. 45 and 46), were si m i l a r while they were both on spring growth winter range forage (premigratory). While the experimental group 90 88 86 co 84 o z 82 2 80 z 78 £ 76 I  72 1 70 CD 68 LLI 3 66 ce tu 64 < 62 60 ACTUAL WEIGHT CHANGE CALCULATED WEIGHT CHANGE PREMIGRATORY P0STMIGRAT0RY APR. MAY + WT. in Kilograms F I G U R E 45. JUN. JUL. JUL. AUG. SEPT. OCT. DATE BODY WEIGHT TAKEN (END OF MONTH) NOV. FEB. MAR A comparison of the calculated weight and actual body weight change for the control group. 152 148 144 140 136 132 128 124 120 116 112 108 104 100 96 92 88 84 < oz 80 76 72 68 64 60 h A C T U A L BODY WEIGHT C A L C U L A T E D BODY WEIGHT PREMIGRATORY (36.8)/' 71.3 S (32.4) /' ^74 ^y (33.6) 65 • ( 2 9 . 5 ) ^ ^ ^ 6 7 (30.5) 138.6 (63.0), / / / / / / / X89.6 (40.7) 105.6 (48.0^/ / / 120 / (54.5)/ / / / / MIGRATORY 145.8 (66.3) 140.1 .(63.7) \ \ \ \ \ 123.0 \ (55.9) \ \ \ 110.1 (50.0) POSTMIGRATORY APR. MAY JUN JUL. JUL. AUG SEPT OCT NOV FEB W T in kilograms DATE BODY WEIGHT . TAKEN (END OF MONTH) MAR. F I G U R E ! 46. A comparison of the calculated weight and actual body weight change for the experimental group. 1 4 5 subsisted on summer range forage, actual body weight continued to increase s t e a d i l y . The greater body weight achieved by the experimental group by the end of the migratory period demonstrates the superior q u a l i t y of the summer range forage. In f a c t , at peak autumn weights (actual) (October) t h i s group was 7.5 Kg (17.5 percent) heavier than the control group. The difference between groups at t h i s time, so far as calculated weights are concerned was 31.5 Kg. or 47.5 percent. The winter weight experience of the two groups further demonstrates the energetic advantages gained by the experi-mental animals fed through the summer on the d i e t simulating that obtained v i a migration. Whereas the spring weight of the control animals was the same at 2 years as i t had been at 1 year the mean weight of the experimental group was 7.3 Kg (25%) above that of a year e a r l i e r . . Both groups l o s t weight through the winter. The control group l o s t 2 0 percent of i t s October weight during the days (150 - 160) October to March (7.04 Kg) while the experimental group l o s t only 14 percent, (5.9 Kg). F i e l d weights for bighorn sheep i n t h i s area are r e l a t i v e l y scarce but Stelfox (1971) states that sheep i n Jasper sustain a 20 percent overwinter weight loss on an unproductive range (133 lb/acre; a i r - d r y ) . Those i n Waterton sustain only a 13 percent loss on a range more than 3 times productive (410 - 425 lb / a c r e ) . 146 Calculated weights for my experimental group i n February (55.9 Kg) c l o s e l y a l i g n with those c o l l e c t e d i n Banff Park during the same month (57.3 Kg). Also, Blood, et a l . (1970) give the weights of 2 year old ewes as 50.0 to 56.8 Kg. The calculated body weights achieved by the experimental group a l i g n with these f i e l d weights while the actual body weights during the same month were only s l i g h t l y helow the above f i e l d weights. At the s t a r t of the experiment, the actual weights of the 3 one year old ewes used i n t h i s study (28.6 - 29.5 Kg) were i d e n t i c a l to those given by Blood et a l . (op. c i t . ) for equal aged wild ranging animals (29.5 Kg) . My calculated body weights are somewhat closer to f i e l d weights taken by other workers than are the actual weights, when compared i n late winter. The difference between winter ranges i n and out of the parks (heavily grazed by cattle) may p a r t i a l l y account for t h i s difference between actual weights and f i e l d weights obtained i n parks. Also, the high rate of gain achieved during a t r i a l on summer range forage (used to form the calculated weight) (see methods) could not be maintained between t r i a l s (when actual weights were taken) for various reasons associated with pen feedings. Apparent d i g e s t i b i 1 i t y . A more intensive study of the apparent d i g e s t i b i l i t y of dry matter was conducted on both 147 winter and summer range forages during.1969-70. D i g e s t i -b i l i t y was determined at monthly i n t e r v a l s throughout the year with the exception of the coldest winter months (Fig. 47). Apparent d i g e s t i b i l i t y of winter range forage declined approximately 36 percent (79 to 43 percent) from A p r i l 1969 to A p r i l 1970 . During the; premigratory period, average d i g e s t i b i l i t y was 70.8 percent for the two groups on spring cut winter range forage. For the control group mean d i g e s t i b i l i t y declined during the period July through September to approximately 5 5.8 percent. At the same' time, the experimental group which was now on summer range forage (migratory period) experienced an increase i n d i g e s t i b i l i t y to 71.36 percent. Thus, migratory bighorn sheep are able to maintain apparent d i g e s t i b i l i t y above 70 percent from A p r i l u n t i l October or possibly November. Maturation of winter range forage (leaf to seed stage) probably accounts for the 15 percent decline (absolute terms) i n d i g e s t i b i l i t y between May and July experienced by the control group. This produced a 15.6 percent difference (absolute terms) i n average d i g e s t i b i l i t y between the control and experimental groups during t h i s period. Apparent d i g e s t i b i l i t y (Fig. 47) increased s l i g h t l y (53 to 59 percent) for the control group during the f a l l . This change may be the e f f e c t of f a l l regrowth improving p a l a t a b i l i t y due to some chemical change although crude BOTH GROUPS ON SPRING CUT WINTER RANGE FORAGE CONTROL GROUP EXPERIMENTAL GROUP MIGRATORY 71.64 POST MIGRATORY 72.O0 70.47 .55.94 .5t.06 • 43.78 APRIL MAY MAY JULY JULY AUG SEPT OCT MARCH 15-20 10-15 15-25 1-7 10-20 10-20 1S-20 9 &-30 •ATE. OF FORGET [XLLECTIDN F I G U R E 47. A d e s c r i p t i o n of the seasonal changes i n apparent d i g e s t i b i l i t y of dry matter and a comparison of d i g e s t i b i l i t y between the co n t r o l and experimental groups. CO 149 protein and gross energy remained r e l a t i v e l y stable. In October, the experimental group was changed from alpine to winter range forage i n order to complete the simulation of the actual migratory pattern (postmigratory). During the change i n forage type and q u a l i t y } d i g e s t i b i l i t y declined from 70.5 to 53 percent, reaching a point 3.0 percent (56 Vs. 53 percent) below that for the control group on s i m i l a r winter range forage at the same time. During the winter period the control group experienced, a greater decline i n mean apparent d i g e s t i b i l i t y (12 percent between October and April) than did the experimental group (2 percent between October and A p r i l ) . Voluntary feed intake. Voluntary feed intake was determined d a i l y throughout the year i n order to obtain a seasonal cycle of representative feed intake. A summary of average d a i l y feed intake and feed intake per kilogram of body weight i s given i n Table 38 and Figure 49 for the control and experimental groups. A comparison between groups for each measurement i s given i n Figures 48 and 49. The f i r s t expression of feed intake allows us to estimate forage removal from the range (see section on yearly feed intake) and w i l l eventually lead to an estimate of carrying capacity as range production figures become avai l a b l e . The expression on a body weight basis allows us to re l a t e feed intake to forage q u a l i t y changes without the influence of body Date Forage Cut Average Feed Intake Gm/Day Control Group .Sample Size N Standard Error of the Mean Average Feed Intake Gm/Day Exp. Group Sample Size N Standard Err o r of the Mean A p r i l 15-20+ 614.39 7 (male) + 29.53 614.39 7 (male) + 29.53 May 10-15+ 472.53 7 (male) + 15.86 472.53 7 (male) + 15.86 801.70 14 + 34.99 801.70 14 May 15-25+ 631.41 7 (male) + 22.57 631.41 7 (male) + 22.57 912.09 21 + 27.22 912.09 21 + 27.22 Ju l y 1-7 981.73 14 + 27.25 1078.26 14 + 61.09 J u l y 10-20 1022.54 14 + 40.49 1154.50 21 + 59.91 August 10-20 994.34 14 + 27.12 1202.77 21 + 52.50 Sept. 15-20 850.93 14 + 33.14 1195.94 21 + 51.19 October 9 681.54 14 + 24.46 811.08 21 + 57.04 March 6-30 538.73, 14 + 28.19 544.91 21 + 47.74 + Premigratory period. A l l sheep as one group. TABLE 38. The average feed intake per day for the co n t r o l and experimental groups while on forage cut during 1969-70. BOTH GROUPS ON SPRING CUT WINTER RANGE FORAGE CONTROL GROUP EXPEIUMENTAL GROUP PREMIGRATORY MIGRATORY POST MIGRATORY EXR 29.5 CONT. F I G U R E BODY WEIGHT IN KILOGRAMS 48. A comparison of average d a i l y feed intake between a migratory and non^ micrratorv crrouo of vp.arli.no shupn. 37-'36 35-34-£ 33-«> 32 < 31 -ce o 30-5 29 28 27 26 25 24 ? 23 D 22 UJ UJ CO < ui UJ 20 < UJ > < 19-18 -17 -16-15-.36.52 36.93 PREMIGRATORY \ I A \ \ \ MIGRATORY __?2.°9 31.99 28.45 X30.07 X BOTH GROUPS ON SPRING CUT WINTER RANGE FORAGE CONTROL GROUP EXPERI1CNTAL GROUP + 4-POST MIGRATORY .20.83 2058 J9.I2 \ \ \ \ 15.59 + \ M A R C H 6 - 3 0 A P R I L M A Y M A Y J U L Y J U L Y A U G S E P T O C T 1 5 - 2 0 1 0 - 1 5 1 5 - 2 5 1 - 7 1 0 - 2 0 1 0 - 2 0 1 5 - 2 0 9 DATE OF FORAGE CDLLETTIDN F I G U R E 4 9 . A comparison of for a mi' nra -t-nrv average feed intake/kilogram body weight - m i r r r f l t n r w n r o n n n f v o a r l i n r t c i ' n o o n . 153 weight fluctuations which normally occur throughout the annual cycle. Actual d a i l y feed intake i s shown separately f o r the male y e a r l i n g (Table 38) during A p r i l , May and June a f t e r which i t s weight and feed intake approximated that of the y e a r l i n g ewes i n the experimental group and was included i n the average. Average d a i l y feed intake increased (Fig. 48) from early spring u n t i l mid and late summer for the control (39.9 percent) and experimental groups (48.8 percent) of sheep respectively. During l a t e summer and early f a l l feed.intake began to decline for each group and continued to do so throughout the winter, reaching minimum level s i n early March. Actual feed intake was greater at a l l times for the experi-mental group since they were heavier and thus had a greater active body mass to maintain (Fig. 46). The maximum to minimum decline for the control group was 47.3 percent and for the experimental group, 54.6 percent. During the migratory period (Fig. 48) the experimental group took i n approximately 195.4 grams/day more feed than d i d the control group. Even though the experimental animals were now heavier than the controls (Fig. 45) there i s a r e a l d i f f e r -ence i n feed intake on a body weight basis (Fig. 49). The experimental group ingested 32.77 grams of feed/Kg body weight while the control group ingested only 2 7.92 grams/Kg BW. 154 In the postmigratory period (October to March) the experimental group took i n only 67.9 grams/day more than the control group. However, body weight differences between the two groups (see F i g . 45 & 46) r e s u l t i n a lower feed intake for the experimental group (17.4 gm/Kg BW) than for the control group (20.7 gm/Kg BW). Improved d i g e s t i b i l i t y for the experimental group at t h i s time, as shown previously (Fig. 47), may p a r t i a l l y account for the lower weight loss at a corresponding lower feed intake for t h i s group. I t i s possible also that the experimental animals, by v i r t u e of t h e i r greater weight gain during the summer period, have more stored f a t and are able to use i t during the c r i t i c a l winter period. Thus, a one pound weight loss for the experimental group composed mainly of body f a t contributes 426 4 Kcal to the active metabolic system whereas a one pound loss for the control, possibly composed mainly of proteinaceous tiss u e contributes only 2585 Kcal. At t h i s time the experimental group retains nitrogen more e f f i c i e n t l y than does the control group i n terms of BW and BW'^ (see section on nitrogen balance). The lowest feed intake for both groups occurred during March and A p r i l while on over-wintered forage and at a time when the animals were i n t h e i r poorest condition. For the experimental group on A p r i l cuts of winter forage and during the period on summer range forage, feed intake remained above 30 gm/Kg BW. This was associated with 155 periods of a c t i v e weight ga i n (.20 Kg/day; on s p r i n g cut winter range forage and .23 Kg/day on summer range f o r a g e ) . By comparison, domestic lambs and ewes g r a z i n g on a l p i n e ranges gained .20 and .13 Kg/day, r e s p e c t i v e l y , w h i l e f r e e g r a z i n g and .18 and .12 Kg/day, r e s p e c t i v e l y , w h i l e under the c o n t r o l of a herder ( S t r a s i a et a l . 1970). In May, feed i n t a k e dropped t o 25 gm/Kg BW and 2 9 gm/KG BW ( F i g . 49) during two feed t r i a l s on winter range forage (CP and GE d e c l i n e d during t h i s p e r i o d ) . These values were accompanied by weight gains of .09 and .15 Kg/day. . The average feed i n t a k e f o r the experimental group was 33.53 grams per kilogram body weight during periods of more a c t i v e weight gain whereas i t averaged 31.71 durin g the e n t i r e p e r i o d ; A p r i l 1 to October 1, when weight gains were between .09 and .23 Kg/day. The crude p r o t e i n to gross energy r a t i o averaged 3.2 during the pe r i o d of body growth, i n d i c a t -i ng an adequate balance. In c o n t r a s t , the c o n t r o l group had an average feed in t a k e of 27.92 grams per kilogram body weight during the mi-gra t o r y p e r i o d w h i l e making none to only s l i g h t weight g a i n s . The crude p r o t e i n to gross energy r a t i o d e c l i n e d to 1.3, i n d i c a t i n g major d i f f e r e n c e s between n u t r i e n t content of the forage given to the two groups of sheep d u r i n g t h i s p e r i o d . In the postmigratory p e r i o d the r a t i o . f e l l to 20.70 gm/Kg and 17.36 gm/Kg f o r the c o n t r o l and experimental groups, r e s p e c t i v e l y . The experimental group entered t h i s p e r i o d a t a higher body weight, achieved on the high q u a l i t y 156 summer range feed. The change to winter range feed produced a sharp decline i n feed intake with only s l i g h t changes i n body weight, thereby reducing the r a t i o below that of the control group. Data presented in t h i s section would indicate that where feed intake of the nature and q u a l i t y used i n t h i s expe-riment i s over 30 grams per kilogram body weight the yearling animals are a c t i v e l y gaining weight. When i t i s between 24 and 2 9 they are at maintenance, approximately, or gaining s l i g h t l y . When i t drops below 24 the animals begin to lose weight. Feed intake and apparent d i g e s t i b i l i t y . Previously i t was demonstrated that feed intake and the apparent d i g e s t i -b i l i t y of dry matter cycle seasonally. Both variables are dependent upon forage q u a l i t y , e s p e c i a l l y crude protein content (Wilson and McCarrick, 1966) . Only feed intake i s affected by body weight change. Combined data for both groups of animals indicate a s i g n i f i c a n t r e l a t i o n s h i p between feed intake and d i g e s t i b i l i t y (Fig. 50). This occurs as CP declines and body weight changes as i n Figure 45 and 46. Expression of t h i s r e l a t i o n s h i p f o r the ind i v i d u a l groups indicates a nonsignificant r e l a t i o n s h i p (Fig. 52) for the control group (p = .30), probably due to the influence of body weight on feed intake, yet a s i g n i f i c a n t r e l a t i o n s h i p (Fig. 51) for the experimental group (p = .0048). In a comparison of the two groups (without the influence of body weight) i t i s evident, that the experimental 157 17 16 15j o © 13 * 12 | l 1 E 10 LU 9 z 8 Q LU LU FIGURE 50. 30 34 38 42 46 50 54 58 62 66 70 74 78 82 86 APPARENT DIGESTIBILITY OF DRY MATTER (%) The r e l a t i o n s h i p between feed intake and apparent d i g e s t i b i l i t y of dry matter for both groups of sheep under the influence of dietary q u a l i t y (CP) and body weight change. 158 1300.04. 1200.0 Y = - 535.8 +22.93 x + 8.94 P = .0048 55.0 A P P A R E N T GO.O D I G E S T I B I L I T Y 65.0 I N P E R C E N T 75.0 The r e l a t i o n s h i p between the apparent d i g e s t i b i l i t y of dry matter and d a i l y feed intake for the experimental group on winter and summer range forage (average values). IGURE 52. The r e l a t i o n s h i p between the apparent d i g e s t i b i l i t y of dry matter and feed intake/kilogram body weight f o r the c o n t r o l group (average v a l u e s ) . 40.0+ APPARENT DIGESTIBILITY IN PERCENT FIGURE 53. The r e l a t i o n s h i p between the apparent d i g e s t i b i l i t y of dry matter and feed intake/kilogram body weight f o r the experimental group (average values). •-* 160 X O 37 36 35 34 33 32 31 30 k U £ 29 > 2d g 2 7 CQ 26 J>25 E* 24 ^ 23 Z ~ 22 <* 20 5 19 Q 13 UJ 16 15 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 APPARENT DIGESTIBILITY OF DRY MATTER ( % ) FIGURE 54. The r e l a t i o n s h i p b e t w e e n f e e d i n t a k e / k i l o g r a m b o d y w e i g h t a n d a p p a r e n t d i g e s t i b i l i t y o f d r y m a t t e r u n d e r t h e common i n f l u e n c e o f d i e t a r y q u a l i t y . 161 group o f a n i m a l s ( F i g . 53) responded more a c t i v e l y t o i n c r e a s e d d i g e s t i b i l i t y t h a n d i d t h e c o n t r o l group ( F i g . 5 2 ) . These d a t a have been computed from average v a l u e s f o r each group. F o r example, a 5 p e r c e n t i n c r e a s e (60 t o 65 p e r c e n t ) i n d i g e s t i b i l i t y o f t h e f o r a g e p r o v i d e d t o each group r e s u l t e d i n an i n c r e a s e o f 3.59 grams o f feed/Kg BW/day f o r t h e e x p e r i m e n t a l group b u t o n l y 1.66 grams o f feed/Kg BW/day f o r t h e c o n t r o l group. I f t h e p r o t e i n v a l u e s o f b o t h d i e t s were t h o s e o f t h e w i n t e r range f e e d p r i o r t o m i g r a t i o n ( a p p r o x i m a t e l y 10 p e r c e n t ) t h e d i f f e r e n c e i n f e e d i n t a k e a t 60 - 65 p e r c e n t d i g e s t i b i l i t y (1.93 grams/Kg BW/day) between t h e two g r o u p s , would r e s u l t i n t h e e x p e r i m e n t a l group r e c e i v i n g .20 grams o f p r o t e i n / K G BW/day more t h a n t h e c o n t r o l group. A c t u a l l y , t h e maximum p r o t e i n c o n t e n t and t h e p e r i o d o f use o f summer range f o r a g e by t h e e x p e r i m e n t a l group i s much g r e a t e r (16-17 p e r c e n t f o r 4 months v s . 14 p e r c e n t f o r 1 month) and t h e p r o t e i n g a i n o f t h a t group o v e r t h e c o n t r o l group i s c o r r e s p o n d i n g l y g r e a t e r . The m a j o r i t y o f p o i n t s i n t h e r e g r e s s i o n o f f e e d i n t a k e and d i g e s t i b i l i t y f o r t h e c o n t r o l group f a l l below 30 grams o f feed/Kg BW ( F i g . 5 2 ) . F o r t h e e x p e r i m e n t a l group a t l e a s t h a l f t h e p o i n t s f a l l above 30 grams o f feed/Kg BW ( F i g . 5 3 ) . Thus, i t i s e v i d e n t t h a t f o r a g e q u a l i t y and s p e c i e s c o m p o s i -t i o n a r e s t i m u l a t i n g a g r e a t e r f e e d i n t a k e and t h e r e i n a g r e a t e r n u t r i e n t i n t a k e f o r t h e e x p e r i m e n t a l group a t h i g h e r l e v e l s o f d i g e s t i b i l i t y . 162 Feed intake and apparent d i g e s t i b i l i t y decline simultaneously, with season, to about 15-20 grams/Kg BW/day at a d i g e s t i b i l i t y of 44-50 percent (Fig. 54). Thus, low values occur i n late winter on dormant, low q u a l i t y forage. I t i s evident that the dietary experience of the experimental group, with i t s period upon high q u a l i t y summer range feed, equips t h i s group to digest even the low q u a l i t y diets (50-51 percent d i g e s t i b i l i t y ) , experienced when i t returns to winter range feeds i n the autumn, more e f f i c i e n t l y than does the control group (44 percent d i g e s t i b i l i t y ) . .Feed Intake.- D i g e s t i b i l i t y Changes and the E f f e c t . on Nutrient Intake E a r l i e r sections described important n u t r i t i o n a l differences between the two groups of sheep, with the migratory group being superior i n each category. Within each group (adult and y e a r l i n g sheep) i t was noted that certain i n d i v i d u a l s ingested higher quantities of feed which i n turn lowered the apparent d i g e s t i b i l i t y of that feed. The following data t e s t the idea that t h i s combination of feeding and d i g e s t i b i l i t y i s n u t r i t i o n a l l y superior and w i l l promote greater survivorship among individ u a l s of t h i s type. Blaxter and Wilson (1962) show that the apparent d i g e s t i b i l i t y of hay of a given n u t r i t i o n a l q u a l i t y f e l l with increasing intake. In my study, feed intake for the i n d i v i d u a l adult ewes on the standard r a t i o n 36-57 (Table 39) ranged from 767.61 to 1209.84 grams per day. This increase was Description of Diet Feed Intake gm/day/animal Apparent D i g e s t i b i l i t y o„ "o Digestible Protein Intake gm/day/animal Age of Status Animal Ration 36-57 767.61 1198.48 1209.84 86 .1 83.2 78.9 134.77 190.20 197.29 Adult Alpine Forage 579.76 1034 .98 1321.00 68.1 65.1 61.6 48.19 88.77 . 107.03 Adult Alpine Forage Early Cut 1104.03 1422.96 77.29 70.46 142.65 170.85 Yearling Alpine Forage Later Cut 1249.23 1343.60 75.28 71.45 111.49 118.06 Yearling Table 39. The change i n d i g e s t i b i l i t y for individuals of the adult and y e a r l i n g groups, as affected by l e v e l of feeding. 164 accompanied by a d e c l i n e i n d i g e s t i b i l i t y from 86.1 to 78.9 percent r e s p e c t i v e l y . However, the animal w i t h the higher feed i n t a k e , d e s p i t e the lowered d i g e s t i b i l i t y , acquired 197.29 grams of DCP/day w h i l e the one w i t h the lower feed i n t a k e acquired 134.77 grams of DCP/day. This r e l a t i o n s h i p was s i m i l a r when the ewe group was maintained on a l p i n e forage. Again the g r e a t e s t DCP in t a k e (107.03 gm/day) was a s s o c i a t e d w i t h the hi g h e s t feed i n t a k e (1321 gm/day). The r e l a t i o n s h i p was confirmed w i t h the y e a r l i n g group (Table 39). Body weight d i f f e r e n c e s were minimal d u r i n g the comparison of i n d i v i d u a l s on any of the described r a t i o n s , and should not produce s i g n i f i c a n t d i f f e r e n c e s i n feed i n t a k e among i n d i v i d u a l s of a group. These data i n d i c a t e t h a t i n d i v i d u a l s which i n g e s t h i g h q u a n t i t i e s of summer or winter range feed, w h i l e s a c r i -f i c i n g e f f i c i e n c y of d i g e s t i o n , s t i l l b e n e f i t i n terms of n u t r i e n t i n t a k e . This i s a sharp d i s t i n c t i o n from d e c l i n e s i n feed i n t a k e and d i g e s t i b i l i t y t h a t a r i s e from reductions i n feed q u a l i t y (CP content) (Table 38). Subsequently, a comparison of the a d u l t ewe group as a u n i t w h i l e on d i e t s d i f f e r i n g i n q u a l i t y (CP content) i n d i c a t e s t h a t feed i n t a k e d e c l i n e s throughout the year i n response to d e c l i n i n g d i e t a r y q u a l i t y , without improvements i n d i g e s t i b i l i t y or n u t r i e n t i n t a k e (Table 40). In t h i s i n s t a n c e d i g e s t i b i l i t y and DCP p a r a l l e l e d Description Quality of of Diet Diet Crude Protein Feed Intake gm/day/group Apparent D i g e s t i b i l i t y Digestible Protein gm/day/group Age Status of Animal Mainly Agropyron Mainly Agropyron Mainly Agropyron Mainly Agropyron 5. 87 4.78 3.44 3.22 998.18 910.83 850 .92 681.54' 50 .6 38.16 58.99 55.94 20.53 -2.72 10 .06 5.48 Adult Adult Yearling Yearling Table 40. The change i n d i g e s t i b i l i t y for the adult and yearling animals as a uni t , i n r e l a t i o n to l e v e l of feeding and qua l i t y of the d i e t . H 166 declines i n feed intake and dietary q u a l i t y i n contrast to the previous experiment where d i g e s t i b i l i t y increased as feed intake declined. Results were s i m i l a r when tested with the yearling animals (Table 40). A comparison of the two d i f f e r e n t experiments suggests that although dietary q u a l i t y determines the change i n feed intake, apparent d i g e s t i b i l i t y , DCP, etc., i n d i v i d u a l s which have a higher feed intake on any p a r t i c u l a r q u a l i t y d i e t w i l l benefit by receiving a greater nutrient intake. Feed intake and nutrient content of the forage. Crude protein was highest i n spring cut v/inter range forage and alpine range forage (17-18 percent) and proceeded to a mini-mum value (2 percent) i n l a t e winter. Forage q u a l i t y changes of t h i s magnitude have been shown to influence feed intake (Hidiroglou et a l . 1966, Robinson and Forbes, 1970). A second major influence on feed intake i s that of body weight (Fig. 55). The v a r i a t i o n i n points shown by t h i s r e l a t i o n s h i p indicates that factors other than body weight (forage quality) are imposing t h e i r influence. In t h i s regard the feed intake-crude protein r e l a t i o n -ships (computed from average values) are given with and without the influence of body weight. The curve r e l a t i n g feed intake to crude protein of . the feed for the control group i s i n t e r e s t i n g as i t evinces two d i s t i n c t i v e phases (Fig. 56). Thus, as crude protein 167 17 16 15 14 J 3 £121 ^ 1 1 | 10 LU z 8 Q , LU 7 LU 1 » t t • 16 18 20 2 2 24 26 2 8 30 3 2 34 36 38 4 0 42 BODY WEIGHT ( kg ) FIGURE 55. The r e l a t i o n s h i p between feed intake and body weight change for both groups of sheep. 168 content decreases from 11 to 6 percent during the spring and summer there i s a gradual increase i n feed intake from 800 to 1020 grams/day. The change (line "a" i n Figure 56) i s described by the equation Y = 1190.0 - 31.30 x ± 2.61. I t i s s i g n i f i c a n t at the .05 l e v e l (p = .025). This represents a 45.5 percent decrease i n crude protein content of the forage yet only a 31 percent decline i n ingested crude protein i n consequence of a 21.6 percent increase i n feed intake. This indicates an attempt to compensate for declining nutrient qua l i t y of the forage. The point of maximum feed intake was reached at 5.7% CP (1020 gm per day or about 30 gm/Kg BW). Further decline i n protein was accompanied by a s t e a d i l y decreasing feed consumption u n t i l at 2 percent crude protein (line "b" i n F i g . 56), feed intake has declined to 540 grams/ day. The change throughout the winter i s described by the equation Y = 325.5 + 124.IX ± 1.58 and i s also s i g n i f i c a n t at the .05 l e v e l (p = .014). The point of i n t e r s e c t i o n of the two l i n e s ("a" and "b") occurs at approximately 5.7 percent CP. From these data i t may be in f e r r e d that on these types of wild vegetation the animals respond i n feed intake and nutrient extraction so as to grow i n weight where there i s 5.7 CP or better but are unable to do so at lower CP l e v e l s . This value w i l l be examined i n terms of a protein maintenance value i n a l a t e r section. The contrasting seasonal changes between crude protein 169 1100.0. 1000.0 900.0 z UJ 800.01 P 700.01 eoo.oi 500.0 Y = 1190.0 - 31.30 x + 2.61 4.0 6-0 B'O PERCENT CRUDE PROTEIN 10.0 IS'0 F T f n R F 56 The r e l a t i o n s h i p between crude p r o t e i n content of the FIGURE bo. d . e t ^ d a i i y f e e d i n t a k e f o r t h e c o n t r o l group. 170 (gradual decline) and feed intake (increase to mid-summer followed by decline) produce the two phased curve (Fig. 56) for the control group. Where the actual amount of CP ingested/day i s consid-ered under the influence of body weight, i t w i l l be seen that the feed intake at 2 percent CP y i e l d s but 11 grams of CP/ day whereas at 6 percent the intake i s 61 grams; at 7 percent 69 grams; at 10 and 11 percent, despite the lowered feed intake i t i s 91 grams; and 8 8 grams of CP/day, resp e c t i v e l y . I t would appear that increasing crude protein (from 2 to 6 percent) stimulates appetite dramatically for the control group, u n t i l the' maximum gross feed intake of 1020 grams/day i s reached. Thereafter, though gross feed intake declines the amount of CP ingested continues to increase at lea s t to a maximum of 91 grams of CP/day. Increased feed intake i n early spring and summer while CP declines may serve as a compensatory measure to maintain nutrient intake as body weight increases. When crude protein i s used as the independent variable and body weight i s accounted for (Fig. 57) feed intake/kilogram body weight i s d i r e c t l y r elated to the CP content of the forage according to the equation Y = 2 0.53 + .9481X ± 4.12. The r e l a t i o n s h i p i s s i g n i f i c a n t at the .05 l e v e l (p = .012). Also, t h i s indicates that the two phased curve described previously i s affected by changes i n body weight. 171 40.04-EO.O Y = 20.53 + .9481 x +. 4.12 0.0 S'O 4«0 6»0 8«0 10«0 PERCENT CRUDE PROTEIN 15.0 14.0 16.0 FIGURE 57. The r e l a t i o n s h i p between crude p r o t e i n content of the d i e t and d a i l y feed i n t a k e / k i l o g r a m body weight f o r the c o n t r o l group. 172 I t i s not possible to document a two phased curve for the experimental group as there are i n s u f f i c i e n t points for the period on winter range forage to analyze the r e l a t i o n s h i p s t a t i s t i c a l l y . For both groups there i s a period when feed intake increases as CP content declines (under the influence of body weight). Thus, i t appears that compensatory measures are operative for animals using both the summer and winter range i n response to d e c l i n i n g dietary q u a l i t y . The r e l a t i o n s h i p between feed intake and crude protein during a seasonal cycle for a migratory group of bighorn sheep i s shown i n Figure 58. I t i s described by the equation Y = 592.3 + 35.14 x + 5.45 and i s s i g n i f i c a n t at the .05 l e v e l (p = .014) . S i m i l a r l y , when crude protein i s used as the indepen-dent variable and body weight i s accounted for (Fig. 59) feed intake/kilogram body weight i s d i r e c t l y r elated to CP content of the forage for the experimental group. This r e l a t i o n s h i p i s described by the equation Y = 14.33 + 1.296 x + 5.24 and i s highly s i g n i f i c a n t (p = .0002). Thus, crude protein, as. a c r i t e r i o n of forage q u a l i t y , enables one to p r e d i c t feed . intake when body weight change i s minimal for both groups of sheep. The slope of the l i n e s i n Figures 57 and 59 does not appear s i g n i f i c a n t l y d i f f e r e n t (F =1.063, p = .319). The ease of measurement of CP content allows the p r e d i c t i o n of feed intake on a body weight basis and w i l l be useful i n d i e t and feed intake/kilogram body weight for the experimental group. 40*0 + + 4«0 4«i 4-5 4*3 4.4 4. GROSS ENERGY I N KCAL / GM FIGURE 60. The rel a t i o n s h i p between gross energy content of the d i e t and' feed intake/kilogram body weight for the experimental group. 175 the measurement of carrying capacity. There i s evidence to suggest that p a l a t a b i l i t y and species composition produce differences i n feed intake (Table 38) between the control and experimental groups when CP varies between 2 and 17 percent. At 11 percent CP the control group ingests 28.98 gm/kilogram body weight while on winter range feed. By comparison the experimental group ingests 30.77 gm/kilogram body weight while on alpine forage at 11 percent CP. This suggests that some other a t t r i b u t e involved i n p a l a t a b i l i t y or appetite i s operative when sheep are eating alpine vegetation as opposed to that obtained from lowland areas. The r e l a t i o n s h i p between feed intake/ Kg BW and gross energy content of the feed i s expressed by the equation Y =• 181.7 + 48.41 X +' .141 (p = .0001) fo r the experimental group (Fig. 60). This r e l a t i o n s h i p i s not s i g n i f i c a n t for the control group (p = .096) . Crude protein (p = .002) and gross energy (p = .0001) reveal a s i m i l a r r e l a t i o n s h i p to feed intake for the experi-mental group but not for the control group (p = .012 and .096). Feed intake and ambient temperature. The influence of minimum ambient temperature on a i r dry (10 percent moisture) feed intake during the c r i t i c a l winter period of 1969-70 was examined using low q u a l i t y forage (3.3 percent CP) available to the animals during that season. The t e s t was 176 standardized by holding forage q u a l i t y constant and expressing feed intake on a body weight basis. As shown i n Figure 61 feed intake/kilogram body weight increased sharply with d e c l i n i n g ambient temperature and declined gradually with increasing ambient temperature. Thus, feed intake increased 30 percent for the control group while ambient temperature declined from 19°F to -11°F (30°F). An inverse r e l a t i o n s h i p between feed intake/Kg BW and ambient temperature for both groups of sheep i s evident i n Figure 6 2 and 6 3 as ambient temperature increased. Con-sequently, feed intake/kilogram body weight can be predicted from ambient temperature during the c r i t i c a l winter period f o r the control group according to the equation Y = 28.95- .2728 x + 12.87. The r e l a t i o n s h i p i s s i g n i f i c a n t at the .01 l e v e l (p = .007). S i m i l a r l y , t h i s r e l a t i o n s h i p i s described by the equation Y =24.42 - .186 8 x + 11.14 for the experimental group. I t i s s i g n i f i c a n t at the .05 l e v e l (p = .0317). The slope of the l i n e s does not appear to be s i g n i f i c a n t l y d i f f e r -ent (F = .949, p = .352) as both groups responded s i m i l a r l y . Within the described range of ambient temperature feed intake changes .27 gm/Kg BW for each 1°F change i n temperature for the control group and .18 gm/Kg BW for the experimental group. Feed intake began to respond to minimum ambient temperature at 32°F (Fig. 64). During the period November 18 - 22 when ambient temperature was 27-38°F feed intake \ MINIMUM AMBIENT TEMPERATURE CONTROL GROUP EXPERIMENTAL GROUP \ 22 20 18 16 14 12 10 8 6 4 2 0 -2 -4 -6 -8 •10 -12 • -14 -16 DEC 19-25 DEC 26 JAN I JAN 2-8 JAN 9-15 JAN 16-22 JAN 23-29 JAN 30 FEB 5 FEB 5 FEB 12 TIME IN WEEKLY INTERVALS F I G U R E 61. Average d a i l y feed intake/kilogram body weight for the control and experimental groups of sheep i n r e l a t i o n to changes in ambient temperature during the c r i t i c a l winter period. 3 4 -O i . ao«a -15.0 -io«o -5«o o«o 5.0 IO.O i5«o ao«o AMBIENT TEMPERATURE IN F FIGURE 62. The r e l a t i o n s h i p between minimum ambient temperature and feed intake/kilogram body weight for the control group. 30-0+ 1375-1350-1325-1300-1275-1250-1225-1200-> < o 1175-CO 1150 -< CE 1125-o 1100-z 1075-UJ 1050-z 1025-o 1000-u UJ 975-u. 950-925-900-875-850-MINIMUIVT AMBIENT TEMPERATURE AVERAGE FEED INTAKE — A J L 9 10 ll 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 TIME IN DAYS (NOVEMBER) i 4 0 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 o U. UJ CE r -< CE UJ a. UJ i -h-z UJ CD z z z z > _ J < F I G U R E 64. Changes i n minimum ambient temperature and d a i l y f e e d i n t a k e f o r t h e a d u l t ewe group d u r i n g November 1968. 180 was 1187.83 grams/day; 118.16 grams/day or 9.1 p e r c e n t l e s s than when the average temperature was 2 5° F d u r i n g November 23 - 28.. This, change i n feed intake, was r e f l e c t e d a l s o i n crude p r o t e i n i n t a k e which was 6.94 grams/day l e s s and gross energy i n t a k e 509.27 Kcal/day l e s s . Forage q u a l i t y remained c o n s t a n t . d u r i n g t h i s p e r i o d and body weight was approximately s t a b l e . Extremes i n temperature were ex p e r i e n c e d i n l a t e December 1968 ( - 5 0°F ) and January 1969 ( F i g . 6 5 ) . Feed i n t a k e i n c r e a s e d markedly from 750 grams/day p r i o r to the c o l d s p e l l to 1148 gm/day d u r i n g the p e r i o d of extreme c o l d . T h i s i s an i n c r e a s e of 39 7.5 8 grams/day or 34.6 p e r c e n t . Crude p r o t e i n and gross energy i n t a k e s showed a s i m i l a r percentage i n c r e a s e . During the two month p e r i o d of feed i n t a k e and ambient temperature measurement shown i n F i g u r e 65 forage q u a l i t y d e c l i n e d s l i g h t l y . i t has p r e v i o u s l y been shown t h a t the r e s u l t i n g e f f e c t would be a d e c l i n e i n f e e d i n t a k e and body weight. The data i n t h i s f i g u r e i n d i c a t e t h a t the sharp i n c r e a s e i n feed i n t a k e i s a response to ambient temperature. Feed i n t a k e i s s i g n i f i c a n t l y r e l a t e d (p = .0002) t o ambient temperature f o r the a d u l t ewe group ( F i g . 66) a c c o r d -i n g t o the e q u a t i o n Y = 854.7 - 17.05 X + 10.77. W i t h i n the temperature range - 2 0 ° F to 1 0° F each 1° F change r e s u l t s i n a change i n feed i n t a k e of 17.1 gm/day. The r e l a t i o n s h i p between ambient temperature and f e e d intake/day i s e x c e l l e n t p r i o r t o and d u r i n g the c o l d s p e l l f o r AVERAGE FEED INTAKE IN GRAMS / DAY / 7 DAY PERIOD CD C m ON t—1 3 f+uQ CD CD cn CD Hi O 13 3 3 C 3 H 0) 3 cr H-C_| CD 3 r t Cu r t M CD ^ 3 13 SD CD r t CD n c r CD p. P) >< Ml H CD *£> CD C T i DJ • H-3 r t CD t-h O H r t CD -N! ->J ->l ® 00 CO CO 10 CO CO o o p o = = = Oro O I - J ° ro uv ->i o M w -g o ro O J - J Q ro oj O o n O o i O c n O c n O c j i O a i O cn O O oi O ro <- CO > c ro ro o ro ai co Tl m CD 70 70 •< ro o ro -r -r T T - r J_ _l_ _1_ _J I l_ K c o c l i S N O C D c n ^ r o i _ — 4- i i i O N ^ cn co o ro 4> o> co AVERAGE DAILY MINIMUM AMBIENT TEMR IN F 121 1150.0 1100.Ol 1050»0J-alooo.o Z 950.01 hi Z B UJ u. 300.0-L 850.0 800.0. 750.0. -S0.0 Y = 854.7 - 17.05 x + 10.77 -15.0 -10.0 -5.0 0.0 AMBIENT TEMPERATURE I N F 5.0 10 < FIGURE 6 6 The r e l a t i o n s h i p between minimum ambient temperature and d a i l y feed i n t a k e f o r the ad u l t ewe group. 183 the control and adult ewe groups, res p e c t i v e l y . In Figure 62 (designated as 0) and 66 (compensatory points are 1026.5 and. 1131.5 gm feed/day at 15 and 17°F, respectively) two points are out of phase with the described r e l a t i o n s h i p and have not been included i n the c a l c u l a t i o n of the equation. These occurred during the r i s e i n temperature a f t e r the cold s p e l l when there was a lag of about two weeks before nutrient and feed intake returned to the l e v e l i t had been at the same ambient temperature before the cold period. This lag was not noticed with the experimental group (Fig. 6 3) which had been on higher q u a l i t y feed during the summer and was i n better condition throughout the winter months than the control group. Ingested protein. A comparison of the protein intake between the migratory and nonmigratory groups of sheep (Fig. 67) indicates a superior feeding regime for the experimental group although protein intake for each group i s probably con t r o l l e d by s i m i l a r factors (CP and feed intake). Ingested protein for the control group experienced a gradual decline (max. to min. of 87.9 percent) throughout the period of measurement (1969 - 70) while that for the experi-mental group rose to 76.65 gm/day or 84.3 percent correspond-ing to the simulated spring migration but declined sharply during the f a l l and winter. While on overwintered forage, regardless of the previous feeding regime both groups ingested only 11 gm/day. BOTH GROUPS ON S P R I N G CUT WINTER RANGE FORAGE CONTROL GROUP EXPERIMENTAL GROUP POST MIGRATORY FIGURE BODY WEIGHT IN KILOGRAMS 67. The absolute protein intake for the migratory and non-migratory groups of sheep while on forage cut during 1969-70. co 185 The elevated protein intake for the experimental group on alpine forage i s an asset to the yearly protein n u t r i t i o n of an animal. This group took i n approximately 166.44 gm/day during the period they were on alpine forage or about 114.21 gm/day (68.6 percent) more than the control group ingested during the same period. Improved protein intake for the migratory group, e s p e c i a l l y during the winter period, i s primarily but not e n t i r e l y a consequence of larger body weights for t h i s group. For example, during late May the ye a r l i n g groups (30.82 Kg BW) ingested 91.8 grams/day of CP when the forage contained approximately 11 percent CP. By comparison, the experimental group (39.76 Kg BW) ingested 138.62 grams/day of CP from alpine forage that contained 11 percent CP. This becomes 3.0 gm/Kg BW and 3.4 gm/Kg BW for the two periods outlined above. This add i t i o n a l .4 gm/Kg BW probably arises from the greater nutrient content improved nutrient balance and p a l a t a b i l i t y of alpine forage. However, the important finding i s that the experimental group on a d i e t simulating that ava i l a b l e to migratory bighorn was able to mobilize energy and protein resources that permitted greater growth and weight gain than could be provided by the resources available to the control group. Thus, weight gain i s one expression of the advantage gained by migration. The r e l a t i o n s h i p between body weight and protein intake i s further expressed i n Figure 68. The great v a r i a t i o n i n the 186 d i s t r i b u t i o n of points indicates that other factors besides body weight may be a f f e c t i n g CP intake. The r e l a t i o n s h i p appears to be c u r v i l i n e a r as ingested protein remains r e l a t i v e l y constant between body weights of 16 to 32 Kg but increases approximately three times as body weight changes from 32 to 4 2 Kg. The amount of protein ingested i s d i r e c t l y related to the crude protein content of the forage (Figs. 69 and 70). The r e l a t i o n s h i p for the control group i s described by the equation Y = -1.780 + 9.078 X ± 3.29 and i s highly s i g n i f i c a n t (p = < .0001). Thus, each one percent r i s e i n the crude protein content of the forage i s accompanied by a 9.08 gram/ day increase i n protein intake. This r e l a t i o n s h i p for the experimental group i s described by the equation Y = -17.47 + 12.15 X + 5 .45. It i s s i g n i f i c a n t at the .0001 l e v e l (P = < .0001). The slope of the l i n e s expressing the r e l a t i o n s h i p between CP content of the forage and ingested protein for the two groups does not appear to be s i g n i f i c a n t l y d i f f e r e n t (F = 3.3163.and p = .0936) . A s i m i l a r increase i n crude protein content (1 per-cent) of the forage produces a 12.15 gm/day increase i n protein intake. The major difference between groups as far as protein intake i s concerned i s the range of crude protein i n the forage and subsequently the ingested protein a v a i l a b l e to each group. Thus, the control group received about 1.5 grams of ingested 187 350 325 300 275 250 225 D 200] O) 175 Z E 150 H O £ 125| 2 100! UJ S 75 Z 50 25 16 18 20 2 2 24 26 28 30 32 34 36 38 40 4 2 44 BODY WEIGHT IN KILOGRAMS FIGURE 68. The r e l a t i o n s h i p between body weight and the quantity of protein ingested shown as average values, for both groups of sheep. - 1 U - U+ 1 1 1 1 1 1 1 1 1 h 2.0 3>0 4-0 S>0 G-0 7.0 B-0 9-0 10-0 i l « 0 12« PERCENT CRUDE PROTEIN FIGURE 69. The r e l a t i o n s h i p between crude p r o t e i n c o n t e n t o f the w i n t e r range f e e d and i n g e s t e d p r o t e i n , f o r the c o n t r o l group. 189 protein/kilogram of body weight/day and the experimental group 3.9 grams, during the migratory period. Apparent d i g e s t i b l e protein. This section compares the apparent d i g e s t i b l e protein (DCP) intake of the two captive groups of y e a r l i n g sheep and examines some of the factors influencing DCP intake. The influence of feed intake and plant q u a l i t y on nutrient intake and apparent d i g e s t i b i l i t y ; has previously been documented, and r e l a t e d work by S u l l i v a n (1962) indicates that since d i g e s t i b l e protein content i s s i g n i f i c a n t l y correlated to crude protein content, deter-mination of the CP l e v e l of a plant can give a reasonably r e l i a b l e i n d i c a t i o n of i t s feeding value. The decline i n DP values determined at monthly in t e r v a l s (100 percent i n 12 months or approximately 8.5 percent/month) for the c o n t r o l group i s given i n Table 41 and i l l u s t r a t e d in Figure 71. By comparison, d a i l y benefits accrued by the experi-mental group.during the migratory period, i n terms of absolute DP intake (93.63 grams/day or 80.7 percent more than the control group on winter range forage) r e s u l t i n a DP intake greater than the control group of 9363 grams, during a 100 day migratory period. The major monthly decline (50 percent) for the control group i s associated with a l a t e phenological growth stage . (maturation and seedhead development) while the s i g n i f i c a n t increase for the experimental group i n the migratory period Date of Apparent Digestible Percent Digestible Apparent Digestible Percent Dig e s t i b l e Forage Protein (Grams/Day) Protein Protein (Grams/Day) Protein C o l l e c t i o n Control Group Control Group Experimental Group Experimental Group A p r i l 15-20 72.56 82.89 72 .56 82.89 May 10-15 59.54 66.43 59.54 66.43 May 15-25 62.56 73.98 62.56 73.98. July 1-7 31.81 45 .41 117.37 67.79 July 10-20 27.71 45.42 139.73 70.81 August 10-20 19.59 38.13 105.49 6 7. 82 September 15-20 10.06 34.76 101.10 72.92 October 9 5.07 22 .82 1.58 5.96 March 6-30 0(-6.12)* 0 0(-3.19)* 0 * Negative value established by equation (see section: d i g e s t i b l e protein for 1968-69). TABLE 41. The apparent d i g e s t i b l e protein intake and percent d i g e s t i b l e protein for the control and experimental groups of sheep. X 150 140 130 120 110 100 90 8 0 70 60 50 40 30 20 10 0 -10 -20 B O T H G R O U P S C N S P R I N G C U T W I N T E R R A N G E FORAGE C O N T R O L E S S J P — — — EKPERIf.CNTAL GROUP PREMIGRATORY POST MIGRATORY APRIL MAY MAY JULY JULY AUG SEPT OCT MARCH 15-20 10-15 15-25 1-7 10-20 10-20 15-20 9 6-30 • A T E CF FORAGE COLLECTION F I G U R E 7 i . The change i n apparent d i g e s t i b l e protein intake f o r the control and experimental groups of sheep. 4.50 ^ 4.25 >-'4.00 Q O 375 CD 3.50 < 3.25 or O3.00 o =J 2.75 ^ 2.50 W 2.25 ^2.00 ^ 1.75 Z 1.50 £ 1.25 S ioo Q L .75 UJ I -50 CD P .25 UJ 0 Q -.25 -.50 - P R E M I G R A T O R Y x BOTH OTPS OX SPRING CUT WINTER RANGE FORAGE . CONTROL GROUP EXPERIMENTAL GROUP ^ I G RATO RYV / A \ \ POST MIGRATORY APRIL MAY MAY JULY JULY AUG SEPT OCT MARCH 15-20 10-15 15-25 1-7 10-20 10-20 15-20 9 6-30 • A T E OF FORAGE COLLECTION F I G U R E 72. The change i n apparent d i g e s t i b l e p r o t e i n i n t a k e / k i l o g r a m body weight f o r the c o n t r o l and experimental groups of sheep. 193 i s associated with young growing forage i n the le a f stage. Negative d i g e s t i b l e protein values occurred during both years of the study (see F i g . 25 and Table 41) i n la t e winter. These figures resulted from the c a l c u l a t i o n : ingested pr o t e i n - f e c a l protein= d i g e s t i b l e protein. Thus, i t i s l i k e l y that ingested protein i s being digested but i s being masked by losses of metabolic protein. Similar changes occur for percent d i g e s t i b i l i t y of the ingested protein (Table 41). Thus, i t declines 83 percent for the control group over the 12 month period but averages 72 percent for the experimental group on high q u a l i t y feed (premigratory and migratory periods). The control group (Table 42) exhibits a c h a r a c t e r i s t i c decline i n DP/Kg BW/day (Fig. 72) of 100 percent during the yearly cycle. In contrast, r e a l benefits to the experimental group occur during the migratory period when DP intake averages 3.29 gm/Kg BW/day and i s 80.2 percent higher than that f o r the control group. " The DP intake declined from 4.31 to 1.95 gm/Kg BW/day (54.7 percent) during the premigratory period (April through June) under the influence of de c l i n i n g crude protein content of the forage and increasing body weight. Body weight tends to increase with the DP intake for both groups on a vari e t y of feeds given during a yearly period (Fig. 73). The v a r i a b i l i t y i n the d i s t r i b u t i o n of points indicates that factors other than body weight are a f f e c t i n g 194 Digestible Protein/ D i g e s t i b l e Protein/ Date of Forage Kilogram Body Wt. Kilogram Body Wt. Co l l e c t i o n Control Group Experimental Group A p r i l 15-20 4.31 4.31 May 10-15 2 .35 2.35 June 15-25 1.95 1.95 July 1-7 .96 3.94 July 10-20 .78 3.87 August 10-20 .56 2 .79 September 15-20 .28 2.54 October 9 .15 .03 March 6-30 (-.23) 0 (-.092) TABLE 42. The apparent d i g e s t i b l e protein intake/kilogram body weight for the control and experimental groups of sheep. 195 25 24 23 22 21 20 19 ^ 18 I17 e 16 5 15 Q 14 Z12 § 11 z" 10 ? 8 Di CL UJ _J OQ I-</> ui 7 6 5 4 3 2 1 0 -1 F I G U R E 73. 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 BODY WEIGHT IN KILOGRAMS The r e l a t i o n s h i p between body weight and absolute d i g e s t i b l e protein intake f o r both groups of sheep. the DP intake. In t h i s regard the influence of crude protein content of the forage on DP intake/day and percent DP i s given i n Figure 74 and 75, for the control group and Figure 76 and 77 for the experimental group. These regressions are based on average values for each group. The r e l a t i o n s h i p between DP intake and CP content of the forage for the control group (Fig. 74) i s described by the equation Y =-14.59 + 6.624 x + 4.12 and i s s i g n i f i c a n t at the .0001 l e v e l (p = < .0001). S i m i l a r l y , percent DP can be predicted from CP content of the winter range forage (Fig. 75) according to the equation Y = 4.146 + 5.963 x + 4.12. The r e l a t i o n s h i p i s s i g n i f i c a n t at the .0001 l e v e l (p = .0001). These relationships for the experimental group are described by the equations (Fig. 76) Y =-24.57 + 8.908 x ± 5.24 and (Fig. 77) Y = -.5562 + 5.211 x ± 5 . 2 4 . Both are s i g n i f i c a n t at the .0001 l e v e l (p = .0001 and p = .0013). A comparison of the slope of the l i n e s between groups (Fig. 74 and 76) indicates that the crude protein: DP intake/ day r e l a t i o n s h i p i s not s i g n i f i c a n t l y d i f f e r e n t at the .05 l e v e l (F = 2.7688, p = .1183) nor i s the CP/DP r e l a t i o n s h i p (in percent), (Fig. 75 and 77) (F = .304, p = .589). For each one percent increase i n the crude protein content of the winter range forage d i g e s t i b l e protein increases by 6.6 3 grams/day for the control group whereas i t increases 8.91 grams/day for the experimental group on the simulated migratory pattern. PERCENT CRUDE PROTEIN FIGURE 75. The r e l a t i o n s h i p between the crude p r o t e i n c o n t e n t of w i n t e r range forage and p e r c e n t d i g e s t i b l e p r o t e i n f o r the c o n t r o l group. -0 198 DIGESTIBLE PROTEIN IN GRAMS / DAY O. o H P - H . 3 1 <Q » re rt • ic 3- H rt re re p * t-< c r * o p* P' rt » 3 P-rt O • o r e s t t H, in O 3" rt Oi H-pj re re X H, 3 IC tl rt tti CD 3" 0 3 re h >a re o rt n 3" H i C n o a n> oi SiiOH TJ (t> n n> o 1 o> rt p - 3 re 3 a . p -re 3 3 rt rt 3" o oi ro o P- 3 01 rt ua TJ re H. TJ 3 O OJ rt C H TJ (D • 3 PERCENT DIGESTIBLE PROTEIN TJ O H o re rt £ re p - n p - 3 re 3 itP re OJ M i n rt o P-• n w o 3 3 rt CL « 3 - 3-re in p -C TJ re 3 . X 3 cr TJ re re re n rt n S p - n re 3 OJ re re 3 s 3 i a rt re rt 0> 3" p j p . r o o <n H o H OJ « o ua c c re o . •o re • 01 3 TJ OJ H o TJ rt re re H. p-O 3 re 3 O rt O 3 O. rt p - re lO 3 199 Crude protein appears to be the major influence on DP intake/kilogram body weight for both groups (Fig. 78 and 79). The re l a t i o n s h i p for the control group i s described by the equation Y = -1.099 + .3362 x + 4.12 and i s s i g n i f i -cant at the .0001 l e v e l (p = .0001). An increase of one percent i n the CP content of the forage produces an increase of .336 grams DP/kilogram body weight. S i m i l a r l y , for the experimental group the r e l a t i o n s h i p i s described by the equation Y =-.8279 + .2956 x ± 5.24 and i s also s i g n i f i c a n t at the .0001 l e v e l (p = .0000). Accordingly, a one percent r i s e i n CP content produces a .297 gram increase i n DP/ kilogram body weight. The slope of the l i n e s i s not s i g n i f i c a n t l y d i f f e r e n t (F = .9695, p = .3415). The control group on winter range forage appears more responsive to changes i n crude protein content as shown by the r e l a t i v e l y superior increase i n DP intake. This improve-ment i n response indicates a lower q u a l i t y d i e t a v a i l a b l e to that group over an extended period of time. The r e l a t i o n s h i p between the apparent d i g e s t i b i l i t y of dry matter and percent DP for the control group i s shown i n Figure 80. I t i s described by the equation Y =-89.23 + 2.255 x + 10.52 and i s s i g n i f i c a n t at the .001 l e v e l (p = .0005). S i m i l a r l y , for the experimental group (Fig. 81) the re l a t i o n s h i p i s described by the equation Y = -141.5 + 2.958 x ± 9.64 and i s also s i g n i f i c a n t at the .001 l e v e l (p = .0003). FIGURE 78. The r e l a t i o n s h i p between the crude p r o t e i n c o n t e n t o f w i n t e r range f o r a g e and d i g e s t i b l e p r o t e i n i n t a k e / k i l o g r a m body weight f o r the c o n t r o l group. S'0+ 0-0 2-0 4-0 G.O 8-0 10>0 12-0 14-0 1G-0 1B-0 PERCENT CRUDE PROTEIN FIGURE 79. The r e l a t i o n s h i p between the crude p r o t e i n c o n t e n t o f w i n t e r and summer range forage and d i g e s t i b l e p r o t e i n i n t a k e / k i l o g r a m body weight f o r the ex p e r i m e n t a l group. ro O O PERCENT APPARENT DIGESTIBLE PROTEIN 102 202 The slope of the lines does not appear s i g n i f i c a n t l y d i f f e r e n t (F = 1.423, p = .2527). Nitrogen balance studies. A quantitative estimation of nitrogen balance depends on the nitrogen ingested, the e f f i c i e n c y with which i t i s used i n the body and the pathways through which i t i s l o s t . D i f f i c u l t i e s a r i s e only when the balance t r i a l i s used to measure absolute instead of r e l a t i v e values, when we assume that p o s i t i v e balance i s i d e n t i c a l with accretion and negative balance with depletion (Duncan, 1967). Nitrogen balance i n the control group exhibits a t y p i c a l gradual decline (Table 4 3) (Fig. 82), from the premigratory (4.99 gm/day) to the postmigratory period (-1.78 gm/day, i n response to s i m i l a r changes i n forage q u a l i t y . The experimental group responded to the high q u a l i t y summer range forage by increasing nitrogen retention from 4.99 gm/day (premigratory) to 10.84 gm/day (migratory) (an increase i n retention of 54 percent). The nitrogen balance achieved by the migratory group on summer range forage i s an improve-ment of 83.7 percent over that for the control group (1.76 gm/day) on winter range forage, at the same time. The r a t i o of N retained/gm of N ingested averaged .33 for a l l sheep during the premigratory period. There i s an improvement i n e f f i c i e n c y of 21.9 percent for the experi-mental group during the change from spring growth winter range forage to summer range forage. By comparison, the improve-ment i n e f f i c i e n c y by the experimental group on summer range Date of Control Group Experimental Group  Forage Nitrogen Balance Protein Balance Nitrogen Balance Protein Balance C o l l e c t i o n i n Grams/Day i n Grams/Day i n Grams/Day i n Grams/Day A p r i l 15-20 5.47 . 34.16 5.47 34 .16 May 10-15 3.81 23.79 3.81 23.79 May 15-25 5.68 35.50 5.68 35.50 July 1-7 1.78 11.15 11.68 73.02 July 10-20 3.11 19 .47 11.99 74.93 August 10-20 1.67 10.47 7.99 49 .91 September 15-20 .47 2.93 11.69 73.06 March 6-30 -1.78 -11.12 -1.43 -8.91 Table 43. A summary of nitrogen balance from the control and experimental groups, with the associated protein balance, during 1969-70. BOTH GROUPS ON SPRING CUT WINTER RANGE FORAGE CONTROL GROUP 5 if) < Q I LU 0£ UJ O O Of —_ EXPERIMENTAL GROUP POST MIGRATORY APRIL MAY MAY JULY JULY AUG SEPT OCT MARCH 15-20 10-15 1S-2S 1-7 10-20 10-20 15-20 9 6-30 DATE CF FORAGE COLLECTION F I G U R E 82. A comparison of nitrogen retention between the c o n t r o l and experimental groups during 1969-70. o 205 forage over the control group on winter range forage i s 51.2 percent. The r e a l benefits to the experimental group over that for the control group i n terms of e f f i c i e n c y of retention, can best be demonstrated when body weight differences are minimal (N retained/Kg BW and/Kg BW « 7 5 ) (Table 44 and 45). At each i n t e r v a l of measurement the experimental group retains a greater proportion of N on i t s simulated migratory regime than does the control group on winter range forage year round. For example, the experimental group retained 83.6 percent more N/Kg BW during the migratory period than did the control group. Similar differences (82.7 percent during the migratory period) e x i s t between groups when N retention i s measured as a 75 function of metabolic body weight (N/Kg BW ). Both methods of measurement show a considerable improvement i n e f f i c i e n c y (.15 gm/Kg BW to .31 gm/Kg BW or 51.6 percent and .34 gm/Kg BW 7 5 to .75 gm/Kg BW 7 5 or 54.6 percent) between early growth winter range forage and summer range forage. Regardless of the difference i n feeding regimes between the two groups p r i o r to entering the c r i t i c a l winter period, nitrogen balance becomes negative on overwintered forage i n d i c a t i n g breakdown of body proteinaceous t i s s u e . By comparison, the control group loses -.15 and the experi-mental group -.10 gm N/Kg BW*75. Date of Forage C o l l e c t i o n , 1969-70 Nitrogen Retained Per Gram of Ingested Nitrogen Nitrogen Retained Per Kilogram Body Weight Nitrogen Retained Per Kilogram Body Weight * 7 5 May 10-15 .27 .123 .29 May 15-25 .39 .18 .42 July 1-7 .16 .054 .13 July 10-20 . 32 .088 .22 August 10-20 .22 .048 .12 September 15-20 .101 .013 .0 32 March 6-30 -1.00 -.068 -.15 Table 44. Nitrogen retained per gram of ingested protein, per kilogram of body weight and per kilogram of body weight*'5 f o r the control group, during 1969-70. O Date of Forage Nitrogen Retained Per Nitrogen Retained Per Nitrogen Retained C o l l e c t i o n , Gram of Ingested Kilogram Body Per Kilogram 1969-70 Nitrogen Weight Body Weight • 7May 10-15 .27 .123 .29 May 15-25 .39 .18 .42 July 1-7 .42 .38 .92 July 10-20 .38 .36 .82 August 10-20 .32 .21 .53 September 15-20 .52 .294 .73 March 6-30 -.79 ' -.042 -.100 Table 45. Nitrogen retained per gram of ingested protein, per kilogram of body weight and per kilogram of body weight*75 for the experimental group, during 19 69-70. 2 0 8 The r e l a t i o n s h i p between the CP content of the forage and r a t i o of nitrogen retention/gram of ingested nitrogen for the control and experimental groups indicates that d i f f e r -ences e x i s t between these groups i n t h e i r a b i l i t y to metabo-l i z e crude protein. These values and those following are based on averages for each group. For the control group t h i s r e l a t i o n s h i p i s not s i g n i f i c a n t at the .05 l e v e l (p = .098) while for the experi-mental group (Fig. 83) i t i s s i g n i f i c a n t at the .01 l e v e l (p = .0089) and may be predicted from the equation Y = -.6685 + .0753 X - 4.67 When body weight i s held r e l a t i v e l y constant, ingested protein i s related to nitrogen retained/kilogram body weight for the control group (Fig. 84) according to the equation Y = -.1061 + .003306 X ± 29.84 (p = .0119) and for the experimental group (Fig. 85) Y = -36.26 + .001970 X + 60.0 (p = .010). The r e l a t i o n s h i p i s highly s i g n i f i c a n t for both groups when DP and nitrogen retention are expressed i n terms of body weight. For the control group (Fig. 86) the equation i s Y = -.01249 + .0 7919 X + 1.46 (p = .0001) and for the experimental group. (Fig. 87) i t i s Y = -.02594 + .09430 X ± 1.4 (p = .0005) . These data indicate the d i r e c t influence of forage q u a l i t y (CP) on protein metabolism. The superior q u a l i t y alpine forage lends i t s e l f to improved nitrogen metabolism \ M Z F I G U R E 8 3 . The r e l a t i o n s h i p between crude protein content of the winter and summer range forage and nitrogen retained/kilogram of nitrogen ingested for the experimental group. 0-4+ 10-0 SO-0 30-0 40.0 50-0 GO-0 70-0 BO'O 30-0 lOO'O INGESTED PROTEIN IN GRAMS / DAY FIGURE 84. The r e l a t i o n s h i p between i n g e s t e d p r o t e i n and n i t r o g e n r e t a i n e d / k i l o g r a m body weight f o r the c o n t r o l group. 0-0 50-0 75-0 IDO'0, 1E5-0 ISO'O 175-0 apO-0 INGESTED PROTEIN IN GRAMS / DAY FIGURE 85. The r e l a t i o n s h i p between i n g e s t e d p r o t e i n and n i t r o g e n r e t a i n e d / k i l o g r a m body weight f o r the exp e r i m e n t a l group. O UJ < f-2 -0-1 -O-S 0>0 0-5 i>0 1-S B.O 5.5 3-0 3-5 4«0 4^5 DIGESTIBLE PROTEIN / KILOGRAM EDDY WEIGHT FIGURE 86. The r e l a t i o n s h i p between d i g e s t i b l e p r o t e i n / k i l o g r a m body weight and n i t r o g e n r e t a i n e d / k i l o g r a m body weight f o r the c o n t r o l group. 0-4+ -0-5 DIGESTIBLE PROTEIN / KILOGRAM BODY WEIGHT FIGURE 87. The r e l a t i o n s h i p between d i g e s t i b l e p r o t e i n / k i l o g r a m body weight and n i t r o g e n r e t a i n e d / k i l o g r a m body weight f o r the e x p e r i m e n t a l group. 212 i n the migratory animal with concommitant changes i n body weight and condition. Ingested energy. The c a l o r i f i c intake as with protein intake, i s greater for the experimental group during a l l periods of measurement i n the annual cycle 1969-70 (Fig. 88). Expressed as energy intake/kilogram body weight i t i s evident that the experimental group gains r e a l advantages i n i t s a b i l i t y to obtain a higher energy input from the summer range (Fig. 89). Energy intake increased gradually from spring (3438.81 Kcal/day) u n t i l midsummer for the control group, remained r e l a t i v e l y stable (4131.54 Kcal/day) u n t i l l a t e summer and declined sharply (2189.22) throughout the f a l l and winter (Fig. 88). The change i s approximately s i m i l a r to that shown by feed intake. The maximum to minimum decline which occurred during the f a l l and winter amounted to 1960.85 Kcal/day or 47.2 percent. For the experimental group energy intake increased 32.6 percent (1709.54 Kcal/day) during the change from spring growth winter range forage to alpine forage but declined 57.7 percent (3029.61 Kcal/day) when returned to dormant forage from the winter range. During the migratory period (approximately 100 days) th i s group ingested 24 percent (5244.24 vs 3984.24 Kcal/day) or 126,000 Kcal more energy than did the control group. X 60-58-56-54 -52-50-48-46 -44-42-40-38-36-34-32-30-28-26-24-22-20 -BOTH GROUPS ON SPRING CUT WINTER FLANGE FORAGE CONTROL GROUP EMPERIKCNTAL GROUP PREMIGRATORY 4081.93 y '3438.81 4-/ ^5797.23 MIGRATORY ' / X N •/ 5257.34^ ^-^5099.37 /4823.02 POST MIGRATORY ' 4150.07 4125.98 - 4 i i a 5 7 4- 4-MAV MAY viULV JULY AUG 10-15 15-55 1-7 10-20 10-SO • A T E CF FORAGE LTLLECTIDN \ 2214.63 2189.22 MARCH 6-30 w V>4 88. Seasonal changes i n average absolute energy intake for the contr o l and experimental groups of sheep during 1969-70. 170 162.0 A / \ 153.7 / \ / MIGRATORY \ POST MIGRATORY X BOTH GROUPS ON S P R I N G CUT WINTER RANGE FORAGE CONTROL GROUP EXPERIMENTAL GROUP 4- 4- 4- 4-83.7 79.7\ \ N64.2 APRIL MAY MAY JULY JULY AUG SEPT OCT MARCH 15-20 10-15 15-25 1-7 10-20 10-20 15-20 9 6-30 •ATE OF FORAGE COLLECTION ro FIGURE 89. Seasonal changes in the ingested energy intake/kilogram body weight for the control and experimental group. 215 72-70-68-66-64-62-60 -53-56-54-52-50-48-46-44-42" 40: 38-36' 34-32" sa -gs-26-24-22-20-18-16-14-16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 B O D Y WEIGHT IN K I L O G R A M S FIGURE 90. The re l a t i o n s h i p between body weight and ingested energy for the control and experimental groups of sheep. 216 C a l o r i f i c i n t a k e expressed as a f u n c t i o n of body weight ( F i g . 89) i l l u s t r a t e s the advantages t o a m i g r a t o r y p o p u l a t i o n o f b i g h o r n sheep. Thus, d u r i n g the m i g r a t o r y p e r i o d the experimental group r e c e i v e s an average of 147.2 K c a l / k i l o g r a m body weight as compared to 115.5 Kcal/Kg BW f o r the c o n t r o l group. T h i s d i f f e r e n c e s h o u l d r e s u l t i n more r a p i d growth and i n c r e a s e d food s t o r e s f o r the m i g r a t o r y group. A l s o , d u r i n g t h i s p e r i o d the average d a i l y c a l o r i f i c i n t a k e f o r f o u r d i g e s t i o n t r i a l s was a s s o c i a t e d w i t h weight gains, o f 10 and 2 kilograms f o r the r e s p e c t i v e groups. Thus, approximately 19 9 2.1 Kcal/day were r e q u i r e d f o r the c o n t r o l group f o r each k i l o g r a m g a i n i n body weight whereas o n l y 524.4 Kcal/day were r e q u i r e d f o r each k i l o g r a m g a i n i n body weight f o r the e x p e r i m e n t a l group. Changes i n energy i n t a k e correspond t o changes i n body weight f o r the two groups o f sheep ( F i g . 90). The v a r i a t i o n i n the d i s t r i b u t i o n of p o i n t s i n d i c a t e s t h a t f a c t o r s o t h e r than body weight a l s o i n f l u e n c e energy i n t a k e . Energy i n t a k e (average v a l u e s f o r the e x p e r i m e n t a l group) appears t o i n c r e a s e w i t h gross energy c o n t e n t o f summer range forage ( F i g . 91 i n Appendix I) and changes a c c o r d i n g to the e q u a t i o n . Y = - 2545.0+ 6857.0 X + .149 (p = .0064). T h i s r e l a t i o n s h i p i s improved (experimental) when body weight change i s accounted f o r as gross energy i s s i g n i f i c a n t l y r e l a t e d to i n g e s t e d e n e r g y / k i l o g r a m body weight ( F i g . 92 i n Appendix I) a c c o r d i n g to the e q u a t i o n Y = -842.1 217 + 222.2 X + .149 (p = .0001). Neither r e l a t i o n s h i p i s s i g n i f i c a n t for the control group (R = .415, p = .307 and R = .574, p = .135) on winter range forage. The regulation of feed and consequently energy intake by the CP content w i l l be discussed l a t e r . These data indicate that diets composed of alpine forage are of superior q u a l i t y and supply more gross energy per unit weight of feed and per unit body weight than does the forage on the winter ranges at the same time of year. Apparent d i g e s t i b l e energy. The s u r v i v a l of wild ungulates through the winter p a r t i a l l y depends on the c a l o r i f i c intake p r i o r to the winter period, which, i f s u f f i c i e n t energy i s available during t h i s period, provides adequate f a t reserves to meet shortages i n the food supply and enables the animals to withstand harsh winter temperatures. The f i n a l analysis of the energy n u t r i t i o n of the two groups l i e s i n the D E f r a c t i o n expressed as D E intake/day and i n terms of body weight and feed intake. The feces account for a minimum of less than 10 percent to a maximum of 70 percent of the heat of combustion of the food ingested (Blaxter, 1962. p. 186). They are by far the most important single factor i n the c a l c u l a t i o n determing the r e l a t i v e n u t r i t i v e value of d i f f e r e n t foods as energy sources. The actual amount of apparent D E absorbed from the digestive t r a c t throughout the year and a comparison between the control and experimental groups i s shown i n Figure 93. X — BOTH GROUPS ON SPRING CUT WINTER RANGE FORAGE CONTROL GROUP POST MIGRATDRY JULY JULY AUG 1-7 10-EO 10-SO • F FCKAGE CCLLECTIQM MARCH 6-30 F I G U R E 93. A comparison of the seasonal, changes of apparent d i g e s t i b l e energy for the control and experimental groups. 219 Digestible energy increased during the premigratory period (April through June) from about 2100 to 2650 Kcal/day for both groups of sheep on s i m i l a r spring cut winter range forage. I t began to decline for the control group during the early migratory period as the forage matured and reached the seed-head stage. The maximum to minimum decline was 63.3 percent. The D E intake increased during the migratory period, for the experimental group reaching a point 37.9 percent above the average intake for the premigratory period. This group took i n approximately 14 31 Kcal/day or 39 percent more than the control group on the corresponding winter range forage. Thus, the experimental group would take i n 143,100 Kcal more than the control group i f the migratory period was approxi-' Tnately 100 days i n length. The.actual benefits (143,100 Kcal of D E and 9363 grams of D P) from a l t i t u d i n a l migration f i n d expression i n an enhanced rate of body weight gain (.23 Kg/day vs. .03 Kg/ day for the control group). Monthly changes in percent D E (Fig. 94) for the two groups of sheep show s i m i l a r seasonal trends as for D E intake. The simulated migration allowed the experimental group to maintain D E at 70 percent for approximately 6 months while the winter range forage given to the control group over the same period produced a 22 percent decline. The d i f f e r -ence i n feeding regimes allowed the migratory group to digest 82-80-78-76 -74-72 -„8t.l7 X BOTH GROUPS ON SPRING CUT WINTER RANGE FORAGE COSVTROL GROUP ^ EXPERIMENTAL GROUP PREMIGRATORY \ POST MIGRATORY 51.86 42.77 APRIL MAY MAY JULY JULY AUG SEPT OCT 15-EO 10-15 15-HS 1-7 10-20 10-HO 15-20 9 • A T E OF FORAGE CCLLECTIQM MARCH 6-30 F I G U R E 94. A comparison of the seasonal changes i n percent d i g e s t i b l e energy between the control and experimental groups. —I 1 — _ _ — I _ 1 — I — . 1 1 [ 1 1— 1 — APRIL MAY MAY JULY JULY AUG SEPT OCT MARCH 15-20 10-15 15-HS 1-7 10-20 10-20 15-20 9 £ -30 •ATE OF FORAGE CTJLLECTION FIGURE 95, A comparison of the digestible energy intake/kilogram body weight between the control and experimental groups, during 1969-70. 222 52 percent of the available energy by winter's end or about 9 percent (52 vs. 43) more than the control group. Also, percent DE declined 14 percentage units for the control group throughout the winter (October to March), but only 2.7 percentage units for the experimental group. The expression of DE intake/kilogram body weight (Fig. 95) allows a comparison of absorbed energy between groups without the influence of body weight changes. During the premigratory period the DE-body weight r a t i o changed i n the same way as gross energy of the forage (Fig. 9). Otherwise, i t declined gradually f o r the control group during the remainder of the year (max to min = 73.9 percent) s i m i l a r to changes described for other energy and protein f r a c t i o n s expressed i n t h i s way. In contrast, the experimental group maintained the DE/kilogram of body weight r a t i o at 102.8 during the migratory period s i m i l a r to the figure for the premigratory period (103.2 Kcal/kilogram body weight). This i s 38 Kcal/kilogram body weight higher than for the control group on winter range forage. Thus, i f the migratory period was 100 days i n length the experimental group would take i n an add i t i o n a l 3800 Kcal/KG BW for the period. This w i l l produce rapid growth (.23 Kg/day) and provide adequate f a t reserves f o r the winter months. The forage intake r a t i o given i n Figure 96 describes the c a l o r i c density of the winter and summer range Ill z Q UJ UJ u. u. o 3.50 3.40 3.30 3.20 3.10 3.00 2.90 2.80 2.70 2.60 v 2.50 o K 2.40 UJ < O UJ < z z UJ UJ _ J CQ 2.30 2.20 2.10 <n 200 UJ (5 Q 1.90 1.80 CONTROL GROUP PREMIGRATfJRY ^ EXPERIMENTAL GROUP X SOTH GROUPS ON SPRING CUT WINTER RANGE FORAGE POST MIGRATORY APRIL 15-HO MARCH 6-30 F I G U R E 96. A comparison of the d i g e s t i b l e energy intake/gram of feed i n t a k e r a t i o between the c o n t r o l and experimental groups, d u r i n g 1969-70. ro 224 diets and i l l u s t r a t e s a comparison of c a l o r i c density of the two forage types given to the control and experimental groups. , The average c a l o r i c density of spring growth winter range feed given during the premigratory period was 3.14 Kcal/gm. The monthly changes i n t h i s period are s i m i l a r to those for the gross energy content of winter range forage (Figure 9). The decline to 2.33 Kcal/gm for the control group during the migratory period i s probably associated with maturation of the forage. C a l o r i c density of summer range forage fed to the experimental group was 3.16 Kcal/gm. The c a l o r i c density continued to decline for the control group during the postmigratory period, reaching 2.07 Kcal/gm during the winter months. I t declined to 2.Q1 Kcal/gm for the experimental group during t h i s period. The r e l a t i o n s h i p between DE intake and body weight i s such (Fig. 97) that forage q u a l i t y was examined as a c o n t r o l l i n g factor for the DE intake. Thus, the two feeding regimes were examined for t h e i r a b i l i t y to supply DE per unit of GE. When body weight d i f f e r -ences are minimal between groups i t i s seen that the winter range d i e t (Fig. 98) supplies 11.1 Kcal DE/Kg BW for each change i n GE of .1 Kcal/gm. Accordingly, the simulated migra-tory d i e t (Fig. 99) supplies 20.6 Kcal DE/Kg BW for a s i m i l a r change i n GE. S i m i l a r l y , the experimental group appears to be s l i g h t l y more e f f i c i e n t i n converting ingested energy to 225 58-56-54-52-50-48-46-44-42 -40-38-36-34-32-30-28-26-24-22-20-18 -16-14-12-10-8 -6 -16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 BODY WEIGHT IN KILOGRAMS F I G U R E 97. The r e l a t i o n s h i p between body weight and the d i g e s t i b l e energy intake for indivi d u a l s of the control and experimental groups of yearling sheep. 130.0+ 4.3 4-4 4.5 GROSS ENERGY CONTENT IN KCAL • 'GM FIGURE 98. The relationship between the gross energy content of winter range forage and the digestible energy intake/ kilogram body weight for the control group. 150.0+ 4.0 4.1 4.5 4*3 4-4 GROSS ENERGY CONTENT IN KCAL / GM 4-5 FIGURE 99. The relationship between the gross energy content of the winter and summer range forage and the digestible energy intake/kilogram body weight for the experimental group. ro 1XX).0+ + INGESTED ENERGY IN KCAL / DAY FIGURE 101. The relationship between the ingested energy content of winter and summer range forage and the digestible energy intake/kilogram body weight for the experimental group. ro 2 2 9 DE/Kg BW. According to the equation Y = -5.503 + .0195 X ± 715.3 (p = .025) the control group (Fig. 100) digests 1.94 Kcal of DE/Kg.BW for each 100 Kcal of energy ingested/day. By comparison, the experimental group (Fig. 101) takes i n 2.33 Kcal of DE/Kg BW for each 100 Kcal of energy ingested/ day according to the equation Y = -18.19 + .0232 X + 1189.0 (p = .0042). Other workers (Blaxter, 1962) suggest that the d i g e s t i b i l i t y of dry matter and energy usually vary by less than 1 to 2 percent. Regardless of the difference i n feeding regimes r e s u l t s for each group are s i m i l a r and support the above statement. For the control group (Fig. 10 2) the r e l a t i o n s h i p i s described by the equation Y = 1.545 + .9682 X + 10.90 (p = .0001) and for the experimental group (Fig. 103) i t i s Y = -2.690 +1.043 X + 9.082 (p = .0001). The d i g e s t i b l e protein to energy r a t i o . Previously, i t was indicated that the CP content of natural forages, and the r e s u l t i n g DP f r a c t i o n was of l i m i t e d value without the corresponding energy measurements. In t h i s regard, the DP/DE r a t i o (Table 46) can be used to describe the r e l a t i o n -ship between these nutrients with season. This r a t i o may serve as an index to describe the o v e r a l l n u t r i t i o n of the animal i n r e l a t i o n to general physical condition and weight change at various points i n the yearly cycle. Preston (1966) suggests a r a t i o of 20.4:1 for maintenance of domestic lambs and one of 22.4:1 for lambs 230 Date of Digestible Protein (Grams/Day Forage C o l l e c t i o n Digestible Energy (meg. cal.) Control Group Experimental Group A p r i l 15-20 34.7 34 .7 May 10-15 28.2 28.2 May 15-25 23.7 23.7 July 1-7 13.6 35.7 July 10-20 12.3 39 .6 August 10-20 8.6 25.1 September 15-20 4.8 27.7 October 9 3.1 1.05 March 6-30 (-6.3) 0 (-2.7) 0 Ratio Table 46. The d i g e s t i b l e protein to energy r a t i o for the control and experimental groups during 1969-70. 231 gaining .4 Kg/day. Robinson and Forbes (1970) suggest a r a t i o of 30:1 for optimum weight change i n lambs. In general, higher d i g e s t i b l e nutrient r a t i o s were associated with higher qu a l i t y (CP) winter and summer range forage. Seasonal trends are s i m i l a r to those for CP (Fig. 7) r e s u l t i n g in. a maximum to minimum decline of 100 percent. .During the premigratory period the r a t i o declined 11 units (31.7 percent) corresponding to phenological changes of the winter range forage from the growing to seed-head stage. The major change (42.6 percent/month) i n the r a t i o , over a short period of time (during June) occurred during the seed-head stage. Accordingly, the r a t i o declined 13.2 "units (July to September) during the period the experimental group was on alpine forage. The r a t i o declined 66 percent, for the control group, between the average for the premigratory and migratory period while increasing 10.8 percent (to 32.02) between these period for the experimental group. This, i n turn, produced a d i f f e r ence of 69 percent between groups on t h e i r respective simulated diets during the migratory period. The maximum r a t i o (39.6:1) was associated with early growth alpine forage of high CP and GE content and produced maximum body weight gains (.23 Kg/day). The association of the d i g e s t i b l e protein to energy r a t i o with body condition presented as body weight change can 232 be shown i n the following manner. In the premigratory period weight accretion of .195 Kg/day was associated with an average r a t i o of 28.91:1. The introd u c t i o n of. alpine forage into the feeding regime caused the r a t i o to increase to 32.02:1 and weight gains to .23 Kg/day. On the winter range, weight accretion became zero to s l i g h t l y p o s i t i v e (migratory period) for the control group as the r a t i o declined from 28.9:1 to 9.8:1. During the c r i t i c a l winter period the r a t i o declined to 0(-1.6) and 0(-.83) for the respective groups while body weight change and nitrogen balance became negative. The negative r a t i o occurs as a r e s u l t of the negative d i g e s t i b l e protein value described e a r l i e r . The d i g e s t i b l e protein to energy r a t i o may be predicted from the simpler crude protein to gross energy r a t i o according to the following equation Y =-8.392 + 13.45.x + .958 (Fig. 104) and Y = -7.475 + 12.41 x + 1.118 (Fig. 105) for the respective groups. Both re l a t i o n s h i p s are highly s i g n i f i c a n t at the .0001 l e v e l (p = < .0001 and p < .0001). This i s an extremely important and useful r e l a t i o n s h i p since a simple r a t i o can be used to calculate a more complex one which can then be associated with body condition and body weight change. Since the seasonal changes i n the DP/DE r a t i o (Table 46) coincide with those of the CP content (Fig. 4 and F i g . 5) for both feeding regimes, i t i s l i k e l y that the CP content 40'Ot-30-0i HD'Ol O.QI -lo-a, , . . . . . . . . 0-0 0-5 1>0 1'5 S-0 5'5 3'0 3'5 CRUDE PROTEIN TO GROSS ENERGY RATIO IN GM/KCAL/GM FIGURE 104. The relationship between the crude protein to gross energy ratio and the digestible protein to energy ra t i o for the control group. _1 < z r -< a: z UJ z M LU I-• a. CL LU _l m M r -in 40-0+ 35-01 30'0l E5-0I 20-Oi P 15'0. 10-0. +-0-0 0-5 1-0 1-5 a-0 5-5 3-0 3-5 4-0 CRUDE PROTEIN TO GROSS ENERGY RATIO IN GM/KCAL/GM FIGURE 105. The relationship between the crude protein to gross energy ratio and the digestible protein to energy ratio for the experimental group. o c DIGESTIBLE PROTEIN TO ENERGY RATIO IN GM/MCAL H, K H 0 01 3" t ft O a t~ «Q o-o a 1 Ml (H Hi n a. o o H-c g o rt ft rt w-0 3"0 ro s rt B- O O !» n M» c o 0. rt 0 ro 3" a o rrTJ « n a 0 0 H-rrifl iO a ro K- w n 3 rt 0 H-c o er •0 0 t-> 3 ID fl-ee 13 3 M, rt 0 rt 0 a> Ml H-3 * h- rt 3 O rt ro ro tl 3 « K 3 >< ro DIGESTIBLE PROTEIN TO ENERGY RATIO IN GM/MCAL 2 3 5 i s the main component determining the d i g e s t i b l e nutrient r a t i o . This i s supported by the high s i g n i f i c a n c e for the r e l a t i o n s h i p between CP content and the DP/DE r a t i o for the control group (Fig. 106) (Y = -8.134 + 3.136 X ± 4.117, p = .0001) and for the experimental group (Fig. 107) (Y = -6.848 + 2.787 X + 5.24, p = .0001). The slope of the l i n e s does not appear to be s i g n i f i c a n t l y d i f f e r e n t according to the analysis of covariance (F = 1.540, p = .234). The f e c a l pathway. Absolute f e c a l weight changed as expected (Fig. 108), i n response to d i g e s t i b i l i t y during the spring to f a l l seasons and as a consequence of lowered d i g e s t i b i l i t y and feed intake during the winter. In a l i k e manner, the digestive e f f i c i e n c y for each group (fecal weight/gram of feed intake) i s i l l u s t r a t e d and compared i n Figure 109. The marked influence of alpine forage on the e f f i c i e n c y of digestion d e f i n i t e l y shows an advantage to a migratory animal. Protein loss by the f e c a l route a r i s i n g from decline i n the weight of feces discharged per day as well as altered concentration of nitrogen per unit of feces can r e f l e c t changes i n dietary q u a l i t y . Change in f e c a l weight under the altered circumstances of the seasons and on the d i f f e r e n t experimental regimens has been described e a r l i e r . In the present study i t can be shown that the change i n protein concentration of the feces i s i n d i r e c t proportion X BOTH GROUPS ON SPRING CUT WINTER RANGE FORAGE CONTROL GROUP EXPERIMENTAL GROUP POST MIGRATORY MAY MAY JULY JULY AUG SEPT OCT MARCH 10-15 15-25 1-7 10-20 10-20 15-20 9 6-30 DATE OF FORAGE COLLECTION F I G U R E 108. A comparison of absolute f e c a l loss for the co n t r o l and experimental groups. ro as X BOTH GROUPS ON SPRING CUT WINTER RANGE FORAGE CONTROL GROUP EXPERIMENTAL GROUP POST MIGRATORY ui Q a u. u. o (3 < o r o r-X o UJ 5 < o UJ MAY MAY JULY JULY AUG SEPT OCT MARCH 10-15 15-H5 1-7 10-HO 10-SO 15-50 9 6-30 • A T E CF FORAGE CCLLECTIOM ro F I G U R E i o 9 . The change i n f e c a l l o s s (gm/day)/gram of feed i n t a k e / d a y f o r the c o n t r o l and e x p e r i m e n t a l groups. 238 to changes i n CP content of the feed (Fig. 7 and 8) f o r both the control and experimental groups (Fig. 110). That i s , i n the control group when feed protein declined from 17 to 2 percent, f e c a l protein went from 12 to 5.7 percent. S i m i l a r l y , the change i n feed protein for the experi-mental group on spring growth (17 to 11 percent) and over-wintered winter range forage (3 to 2 percent) was p a r a l l e l e d by f e c a l protein content (Fig. 110). As a r e s u l t of migration, f e c a l protein concentration increased 54 percent over that for the control group on winter range forage. Robinson and Forbes (19 70) show that v a r i a t i o n i n t o t a l f e c a l nitrogen output between treatments was not s i g n i f i c a n t when dietary crude protein ranged from 7 to 23 percent. The lack of change i s l i k e l y due to the corresponding change i n f e c a l protein concentration shown here. Fecal nitrogen index methods have been developed to estimate " i n vivo" d i g e s t i b i l i t y (Corbett et a l . 1963; O'Donovan et a l . 1967), feed intake (Lancaster, 1949; 1954; M i l f o r d , 1957; Hutchinson, 1958; Fels et a l . 1959) and feed nitrogen (Raymond, 1948). The technique was implemented i n t h i s study for the purpose of estimating the n u t r i t i o n a l parameters l i s t e d above, for the control and experimental groups of bighorn sheep and i n turn to deduce whether differences i n t h e i r feeding regimes produced a s i m i l a r v a r i a t i o n i n p r e d i c t a b i l i t y . The pred i c t i o n of percent crude protein of the feed CO UJ o LU X r-z z u h-o tr CL LL) O ce o I-u o ce UJ CL BOTH GROUPS ON SPRING CUT WINTER RANGE FORAGE CONTROL GROUP EXPERIMENTAL GROUP POST MIGRATORY APRIL MAY MAY JULY JULY AUG SEPT OCT MARCH 15-H0 10-15 1S-25 1-7 10-H0 10-H0 15-HO 9 G-30 • A T E CF FORAGE CCLLECTION F I G U R E 110. The change i n crude protein content of the feces for the control and experimental groups of sheep. 1B.0+ 5.0 7.0 9-0 11-0 13-0 15«0 17-0 1S-0 P E R C E N T C R U D E P R O T E I N I N T H E F E C E S FIGURE 112. The p r e d i c t i o n o f crude p r o t e i n c o n t e n t o f the f e e d from f e c a l p r o t e i n c o n t e n t , f o r the e x p e r i m e n t a l group. no -p>. o "a O APPARENT DIGESTIBILITY IN PERCENT 8 3° 2. N H 6 C ip. m ° M 2 C . M O z ^ 6 BI 8 4^- -p-Dl s 6 from f e c a l protein concentration (based on average values) i s given i n Figure 111 for the control group. I t i s described by the equation Y =-6.987 + 1.797 X + 2.19 and i s s i g n i f i -cant at the .0001 l e v e l (p < .0001). S i m i l a r l y , the r e l a t i o n -ship for the experimental group (based on average values) i n Figure 112 i s described by the equation Y = -.9400 + 1.034 X ± 4.58 and i s s i g n i f i c a n t at the .001 l e v e l (p = .0008). The analysis of covariance indicates that the slope of the l i n e s d i f f e r s i g n i f i c a n t l y (F = 5.033 p = .041). This means that • f e c a l protein can be used as a s a t i s f a c t o r y predictor of crude protein i n the forage. Apparent d i g e s t i b i l i t y may be determined from the composition of the feces (Fig. 113 and 114) , for the two groups of sheep. 0 1 Donovan (1967) has shown that there i s a s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n (+ .92 to + .97) between f e c a l nitrogen and d i g e s t i b l e organic matter for forage at varying stages of maturity. The r e l a t i o n s h i p between apparent d i g e s t i b i l i t y of dry matter and f e c a l protein for the control group (Fig. 113) i s described by the regression equation Y = 30.17 + 3.788 X + 2.19 and i s s i g n i f i c a n t at the .05 l e v e l (p = .0124). In the case of the experimental group (Fig. 114) i t i s described by the.equation Y = 50.53 + 1.426 X + 4.58 and i s also s i g n i f i c a n t at the .05 l e v e l (p = .044). Analysis of covariance indicates no s i g n i f i c a n t difference between slopes (F = 3.275, p = .091). Comparative c o r r e l a t i o n co-e f f i c i e n t values are R = .783 and R = .679. ro 244 The expression of f e c a l protein with feed intake/ kilogram body weight produces a pr e d i c t i v e l i n e a r r e l a t i o n -ship (Fig. 115 and 116) rather than a two phased curve which results from using feed intake/day. According to Forbes (1949) a steady increase i n f e c a l nitrogen excretion per unit of dry matter intake i s found when the protein content of the r a t i o n increases. The regression of f e c a l protein with feed intake/ kilogram body weight for the control group (Fig. 115) i s described by the equation Y =12.96 + 1.783 X ± 2.196 and i s s i g n i f i c a n t at the .01 l e v e l (p = .009). The same regression for the experimental group (Fig. 116) i s described by the equation Y = 13.48 + 1.307 X ± 4.58 (p = .0066). Analysis of covariance indicates that the slope of the l i n e s i s not s i g n i f i c a n t l y d i f f e r e n t (F = .479, p = .50). Absolute protein i n the urine i n r e l a t i o n to urine  volume. The pattern of change i n urine volume d i f f e r e d greatly between the two groups during April'1969 to A p r i l 1970 (Fig. 117). The maximum to minimum decline for the control group was approximately 95 percent. The greatest change (49.4 percent) occurred during the formation of seed-heads i n the forage between May and July. For the experimental group large increases i n urine volume (51 percent) are associated with migration to the summer range. At t h i s time urine volume d i f f e r e d by 80 percent between groups. Trends i n urine volume for each group p a r a l l e l changes X o 'z UJ 2 r> _i o > Ul Z or UJ < ce ui BOTH GROUPS ON SPRING CUT WINTER RANGE FORAGE CONTROL GROUP EKPERIfcOfTAL GROUP POST MIGRATORY APRIL MAY MAY JULY JULY AUG SEPT OCT MARCH 15-20 10-15 15-25 1-7 10-20 10-20 15-20 9 S-30 • A T E C F F C R A G E L J D L L E C T I D N 117. A comparison of the change i n urine volume between the control and experimental groups of sheep. ro VJ1 6 6 6 3 6 0 5 7 5 4 51 4 8 <j 4 5 4 2 3 9 < CC «> 3 6 85 o _ i z I-o cr a. >-cc < z or 3 3 3 3 0 2 7 2 4 21 18 15 12 9 6 3 X BOTH GROUPS ON S P R I N G CUT WINTER RANGE FORAGE CONTROL GROUP / ^ ' 6 - EXPERIMENTAL GROUP / ^ PREMIGRATORY POST MIGRATORY A P R I L MAY MAY J U L Y J U L Y AUG SEPT OCT MARCH 1 5 - 2 0 1 0 - 1 5 1 S - 2 S 1 - 7 1 0 - 2 0 1 0 - 2 0 1 5 - 2 0 9 6 - 3 0 • A T E OF FORAGE COLLECTION FIGURE 118. A comparison of the average absolute protein lost in the urine between the control and experimental group. 247 i n t h e i r r e s p e c t i v e v o l u n t a r y w a t e r i n t a k e s ( F i g . 127) . r e q u i r e d f o r d i g e s t i o n a nd m e t a b o l i s m when t h e f e e d i s g i v e n o n a n a i r d r y b a s i s . C h a n g e s i n w a t e r i n t a k e , f o r a n i m a l s o n t h e r a n g e , a r i s e f r o m p r e f o r m e d w a t e r o f t h e f e e d a nd v o l u n t a r y i n t a k e o f w a t e r a s r e q u i r e d t o m a i n t a i n b o d y f u n c t i o n . C o n s i d e r i n g t h e a v a i l a b i l i t y o f w a t e r o n a l p i n e a nd w i n t e r r a n g e s a n d t h e m o i s t u r e c o n t e n t o f t h e i r f o r a g e t y p e s i t a p p e a r s t h a t b o t h g r o u p s c a n s a t i s f y t h e i r w a t e r r e q u i r e -m e n t s a n d t h a t t h e m e a s u r e d c h a n g e s i n u r i n e v o l u m e ( F i g . 117) p a r a l l e l t h e q u a l i t y o f f o r a g e a n d q u a n t i t y o f w a t e r on t h e r e s p e c t i v e r a n g e . A b s o l u t e u r i n e p r o t e i n l o s s e s ( F i g . 118) f o l l o w a s i m i l a r p a t t e r n t o . t h a t o f u r i n e v o l u m e ( F i g . 117) f o r e a c h g r o u p o f s h e e p . The y e a r l y d e c l i n e i n u r i n a r y p r o t e i n l o s s was 87 p e r c e n t f o r t h e c o n t r o l g r o u p . The e x p e r i m e n t a l g r o u p l o s t a p p r o x i m a t e l y 76 p e r c e n t more p r o t e i n v i a t h i s p a t h w a y d u r i n g t h e m i g r a t o r y p e r i o d t h a n d i d t h e c o n t r o l g r o u p . C h a n g e s i n a b s o l u t e u r i n e p r o t e i n p a r a l l e l t h o s e o f n i t r o g e n b a l a n c e ( F i g . 82) r a t h e r t h a n o c c u r r i n g as a n i n v e r s e r e l a t i o n s h i p as m i g h t ,be e x p e c t e d . As a c o n s e q u e n c e , w h e r e n i t r o g e n r e t e n t i o n i s h i g h l a r g e q u a n t i t i e s o f p r o t e i n ( n i -t r o g e n ) a r e l o s t v i a t h e u r i n a r y p a t h w a y w i t h l a r g e v o l u m e s o f w a t e r . T h i s s e c t i o n p r o v i d e s t h e b a s i c d a t a f o r a c o m p a r i s o n o f t h e e f f i c i e n c y o f n i t r o g e n r e t e n t i o n ( s e e n e x t s e c t i o n ) a n d 2 4 8 allows one to examine more c l o s e l y the benefits of a l t i t u d i n a l migration to a population of bighorn sheep. Differences i n the feeding regime between years produced c o n f l i c t i n g r e s u l t s i n terms of concentration of protein i n the urine. Previously, the percent protein i n the urine (concentration), for the adult ewe group, increased as absolute urine protein declined. This trend was not evident for the y e a r l i n g groups. Percent protein averaged 5.56, 3.58 and 9.63 for the control group during the pre-migratory, migratory and postmigratory periods. For the experimental group i t averaged 5.19, 4.07 and 4.38 percent for the respective periods. •A comparison of f e c a l and urinary protein l o s s . The t o t a l quantity of protein l o s t from the body thru the f e c a l and urinary pathways p a r a l l e l s changes i n nitrogen retention and i s therefore i n d i r e c t l y related to dietary q u a l i t y . Protein removed v i a the urinary pathway i s not l o s t as such but as nitrogen i n the form of urea, ammonia, n i t r a t e s , etc. The term i s used here only for comparative purposes with other protein f r a c t i o n s described e a r l i e r . The expression of f e c a l and urinary protein loss in a r a t i o with d a i l y feed intake (Fig. 119) indicates that protein loss by the f e c a l route for the control group remains almost constant throughout the year regardless of changes i n dietary q u a l i t y . V a r i a t i o n i n f e c a l nitrogen output between treatments was not s i g n i f i c a n t when dietary crude protein . A B S O L U T E F E C A L P R O T E I N / G R A M O F F E E D I N T A K E A B S O L U T E U R I N E P R O T E I N / G R A M O F F E E D I N T A K E .063 .06 POST MIGRATORY .05 < 2 .04 UJ .03 5 .02 .01 .0 APRIL MAY MAY JULY JULY AUG SEPT OCT MARCH 15-HO 10-15 15-2S 1-7 10-20 10-20 15-20 9 6-30 • A T E CF FORAGE CCLLECTIDTM 119. Seasonal changes i n absolute f e c a l and urinary protein l o s s / gram of feed intake for the control group on winter range forage. A B S O L U T E F E C A L P R O T E I N / G M OF F E E D I N T A K E A B S O L U T E URINE P R O T E I N / G M OF F E E D INTAKE POST MIGRATORY JULY JULY AUG 1-7 10-20 10-20 C F F D R A G E L T L L E T T I D N MARCH 6-30 F I G U R E 120. Seasonal changes i n absolute f e c a l and urinary protein l o s s / gram of feed intake for the experimental group on winter and summer range forage. 251 ranged from 7 to 23 percent (Robinson and Forbes, 1970) . In t h i s study, f e c a l protein loss per gram of feed intake i s s l i g h t l y greater for the experimental group i n the migratory period (Fig. 120) under the influence of alpine feed. The greatest difference between groups (compare F i g . 119 to F i g . 120) can be shown i n the pathway of urinary protein l o s s . The control group shows a constant decline from spring to f a l l as crude protein content of the d i e t declines but s t a b i l i z e s at about .01 grams of urine protein per gram of feed intake when CP f a l l s below 6 percent. Conversely, urinary protein loss per gram of feed intake increases from the premigratory to the migratory period for the experimental group. The difference between curves indicates the influence of the better q u a l i t y alpine forage. For the experimental group urinary protein loss also s t a b i l i z e s at approximately .01 grams of urinary prot e i n per gram of feed intake throughout the winter portion of the postmigratory period regardless of the previous influence of alpine forage. That i s , as expected, the two groups perform i n the same way under equivalent conditions of protein input. The expression of f e c a l and urinary protein as a r a t i o with ingested protein serves to exemplify the difference i n dietary q u a l i t y between the winter and summer range and the e f f i c i e n c y of nitrogen u t i l i z a t i o n between the migratory and non-migratory groups of sheep. For example, the r a t i o increased 83 percent for the 252 control group (Fig. 121) from .17 grams of f e c a l p r o t e i n / gram of ingested protein, on spring cut winter range forage, to 1.0 3 on overwintered forage. By comparison, the r a t i o increased 86 percent for the experimental group (Fig. 122) during the same period. This indicates a decline i n the e f f i c i e n c y of protein retention i n the digestive t r a c t , with season. The s l i g h t loss i n e f f i c i e n c y for the migratory group on overwintered forage i s counterbalanced by the constancy of the r a t i o (.32) for t h i s group during the premigratory and migratory periods while that for the control group was increasing. Subsequently, the experimental group on alpine forage i s twice as e f f i c i e n t (.30 grams f e c a l p r o t e i n / gram of ingested protein) as the control group on winter range forage (.60 grams f e c a l protein/gram of ingested protein).during the migratory period. S i m i l a r l y , during the same time period, the control group l o s t an average of .21 grams of urine protein f o r each gram of protein ingested while the experimental group l o s t approximately .28 grams/gram of protein intake. The s l i g h t loss i n e f f i c i e n c y by the experimental group i s again counterbalanced by the large quantity of protein ingested and digested over that for the control group (see e a r l i e r sections on protein intake). A r a t i o was constructed to examine the e f f i c i e n c y of protein retention (DP/protein balance) at various seasons, z UJ ce 0. S 1.051; Z .95 2 O >>. UJ z cc Q z < o Ul U. z Ul f -o ce a. Ul »-3 _J o to co < .90-.85-.80-.75-.70-.65-(3 B0\ .55 UJ .50 X .45 .40 .35 .30 25 .20 .15-.10 ABSOLUTE PROTEIN IN THE FECES/GRAM OF INGESTED PROTEIN ABSOLUTE PROTEIN IN THE URINE /GRAM OF INGESTED PROTEIN A P R I L MAY MAY J U L Y J U L Y AUG SEPT OCT MARCH 1 5 - E O 1 0 - 1 5 1 5 - H S 1 - 7 1 0 - 5 0 1 0 - 2 0 1 5 - E O 9 6 - 3 0 •ATE OF FORAGE COLLECTIDN F I G U R E 1 2 1 . A c o m p a r i s o n o f the s e a s o n a l c o u r s e o f a b s o l u t e f e c a l and u r i n a r y p r o t e i n l o s s / g r a m o f i n g e s t e d p r o t e i n f o r the c o n t r o l group on w i n t e r range f o r a g e . z UJ I-o or CL o ui h-m UJ u. o < or UJ z pr Q Z < CO UJ o UJ U-UJ X z UI o or CL U h-=> _J o CO CO <* 1.30 1.25 1.20 1.15 1.10 l.05|-1.00 .95 .90 .85 .80 .75 .70 .65 .60 .55 .50 .45h .40 .35 .30 25 .20h .15 ABSOLUTE PROTEIN IN THE F E C E S / G R A M OF INGESTED PROTEIN ABSOLUTE PROTEIN IN THE URINE / G R A M OF INGESTED PROTEIN APRIL MAY MAY JULY JULY AUG SEPT OCT MARCH 15-20 10-15 15-2S 1-7 10-20 10-20 15-20 3 6-30 DATE OF FORAGE COLLECTION ro FIGURE 122. A comparison o f the s e a s o n a l c o u r s e o f a b s o l u t e f e c a l and u r i n a r y p r o t e i n l o s s / g r a m o f i n g e s t e d p r o t e i n f o r t h e e x p e r i m e n t a l group on w i n t e r and summer range f o r a g e . 255 P e r i o d E f f i c i e n c y R a t i o ; DP i n gm/Day  N retained/Kg BW C o n t r o l Experimental Premigratory 407.0:1 407.0:1 Migratory 437.0:1 373.4:1 Postmigratory 90.0:1 . 76.0:1 Table 47. The change i n e f f i c i e n c y of ni t r o g e n ' c o n v e r s i o n among seasons f o r the c o n t r o l and experimental groups. 2 5 6 when loss by the f e c a l pathway (DP,= ;ingested p r o t e i n - f e c a l protein) and urinary pathway (protein balance = digested protein-urinary protein) has been accounted f o r . In t h i s regard, e f f i c i e n c y of protein retention increased from the premigratory (2.8:1) to the migratory for the control (2.0:1) and experimental groups (1.7:1) of sheep and i s greater for the experimental than the control group at th i s time. During the postmigratory period the experimental group (76.0:1) i s s l i g h t l y more e f f i c i e n t i n protein retention than i s the control group. S i m i l a r l y when body weight differences are accounted for (DP i n gm/day/nitrogen retained/Kg BW) the experimental group i s more e f f i c i e n t i n converting DP to nitrogen retained during the migratory and postmigratory periods than i s the control group (Table 47). Voluntary water intake. Each r a t i o n used during the digestion t r i a l period was a i r dried to about 10 percent forage moisture. As forage moisture was r e l a t i v e l y constant i t allowed the determination of the e f f e c t s of energy intake on voluntary water intake. In addition to voluntary water intake, preformed water of the feed (10 percent) and metabolic water add to the t o t a l body water pool. Voluntary water intake comprises the bulk of water i n the body water pool (Taylor, 1968). Daily water intake declined s t e a d i l y throughout the 257 year (74 percent) for the adult ewe group (Fig. 123) corresponding to changes i n dietary q u a l i t y . During the l a s t experimental t r i a l , feed intake decreased while q u a l i t y increased s l i g h t l y . The increase i n water intake appeared to be a response to dietary q u a l i t y rather than changes i n dry matter intake. Accordingly, voluntary water intake i s re l a t e d to the DE energy f r a c t i o n (Fig. 124) from the equation Y = -1.111 + .001392 X + 1023.0. I t i s highly s i g n i f i c a n t (p = .0006) . S i m i l a r l y , water intake changes i n response to the DE intake for the control (Fig. 125) and experimental, groups (Fig. 126) of sheep according to the respective equations: Y = -1.015 + .001183 X ± 485.6, p = .02, Y = -1.354 + .001427 X ± 1039.0, p = .0062. In as much as water intake i s re l a t e d to DE i t i s to be expected that the experimental group on alpine forage w i l l reveal a higher intake than w i l l the control group on winter range forage. I t follows that the experimental group i n the migratory period w i l l have a higher water intake (43 percent greater) than when i t i s on vegetation of the winter range la t e i n the premigratory period. The differences between these events i s shown in Table 48 and i l l u s t r a t e d i n Figure 127. In the same way the seasonal decline experienced by both groups when on the low energy winter range feed during the autumn and winter conforms to t h i s g eneralization. 258 5 CO LU or UJ UJ UJ < UJ > < 5.51 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 I.Oh ,5.23 2 . 0 6 19.83 1 3 . 6 8 7.59 CRUDE PROTEIN CONTENT FXbURE. 123. The average d a i l y water i n t a k e f o r the adul ewe group. 259 ±000.0 EOOO-O 3000.0 4000*0 5000.0 DIGESTIBLE ENERGY IN KCAL /DAY FIGURE 124. The re l a t i o n s h i p between water intake and d i g e s t i b l e energy intake f o r the adult ewe group. FIGURE 125. The r e l a t i o n s h i p between water i n t a k e and d i g e s t -i b l e energy i n t a k e f o r the c o n t r o l group. o c rt a ^ 3 - P- !X ro us ro O w n O lt» 3 P- M rt tr o H P> rt 0 O P-M O (» 3 iQ 9 to H, <0 3 1 O « P • c >a -a •a >< tr p-3 rt rt S c ro x ro ro 3 \ * • * P- III p* rt O ro 9 3 rt tr tu o * • a ro S 3 ro a P-iQ rt 3" S-rt ro WATER INTAKE IN LITRES / DAY -P — P-WATER INTAKE IN LITRES / DAY (0 • H cr *a h- ro . ro ro n M . p- ro ro 3 3 M ro ro in 3 « rt rtva p-K O I - 3 P- 0) I 3 3 -I rt P-I ni TJ : x I ro t r \ ro x rt p- * P» ro o ro lO 3 3 * 3 tt rt cr ro o n a >< P-3 t rt ro ID p- *• i o ro 3" rt P 3 M i D* O M Q, P-rt iO 3" ro ro u 192 5.5 5.0 4.5 4 . 0 >-< o 3.5 CO UJ - FTOttGRATORY 3.0 2.5 UJ S 2.0 ce UJ § 1.5 UJ 5 1.0 oc UJ 5 0.5 0 EXPERIMENTAL GROUP \ X BOTH GROUPS ON SPRING CUT WINTER RANGE FORAGE i CONTROL GROUP / \ 5 4 7 / 2.33/ / / / + IGRATORY/ / 4.45 / 4.13 / 2.08 1.98 4-POST MIGRATORY APRIL MAY MAY JULY JULY AUG SEPT 15-20 10-15 1S-ES 1-7 1 0 - 2 0 10-20 15-20 • A T E O F F O R A G E L X L L E T T I O J — r — OCT 9 MARCH G-30 F I G U R E 127. A.comparison of the average water intake between the c o n t r o l and experimental groups, by month. no 263 Date of Average water intake i n l i t r e s / d a y Period Control Group Experimental Group Promigratory May - June 17 2.23 2.23 Migratory June 17 - Sept. 30 1.65 3.9 3 Postmigratory Sept. 30 - March 30 .46 1.60 Table 48. A summary of comparative water intakes between the control and experimental groups for each period. Water intake can also be used to monitor the DE intake/ kilogram body weight for each group according to the respective equations: Y = -.6782 + .03393 X + 18.0, p = .015, (Fig. 128). Y = -1.058 + .0466 X + 31.49, p = .011. (Fig. 129) Solving these equations indicates that the experimental group takes i n .047 l i t r e s / K c a l DE/Kg BW while on the simulated migratory feeding regime while the control group ingests only .0 34 l i t r e s / K c a l DE/Kg BW on winter range forage. An Estimation of Energy for Body Maintenance The energy needs of an animal are described as the food energy supplied equals food energy used for meeting maintenance expenditures plus food energy needed to meet 264 l a c t a t i o n demands plus food energy needed to increase body ' size (Blaxter, 1962). In t h i s experiment food energy supplied equalled food energy used for meeting maintenance expenditure since I used y e a r l i n g animals which were not l a c t a t i n g and maintenance was established at zero weight change. Determination of the energy required to maintain body weight should allow a f i r s t approximation of maintenance during the annual cycle of events facing a migratory and sedentary group of sheep. I t w i l l enable me to ascertain the season at which each group reached maintenance, the length of time spent at maintenance or below and the c l i m a t i c conditions (ambient temperature) occurring at the time maintenance was reached. Ideally, a maintenance curve should be established by season, for each group, i n order to standardize the influence of climate on body weight change and to determine the r e l a t i v e seasonal change i n maintenance requirements. The amount of DE required for maintenance of the control group (Fig. 130) on winter range feed as compared to the experimental group (Fig. 131) on i t s simulated migra-tory d i e t , v/hen important aspects of the yearly cycle (ambient temperature, feed type, etc.) are considered, becomes 65.7 Kcal/Kg BW, according to the equation Y = -.8807 + .01336 X + 18.0 (p = .0122) and 42.4 Kcal/Kg BW, according to the equation Y = -.3101 + .007298 X - 31.49 (p = .0466), for the BODY WEIGHT CHANGE IN POUNDS / DAY respective groups. These r e s u l t s are supported by those of other workers: U l l r e y et a l . (1969), Brockway and Maloiy, (1968) and Cowan et a l . (1957). Brody (1945, p. 483) suggests that the DE requirements for maintenance vary with metabolic body weight (BW*"^). In t h i s regard, the DE requirements become 156.3 Kcal/Kg BW 3 for the control group (Fig. 132) according to the equation: Y = -.5384 + .003443 X + 36 .84 (p = .0017). S i m i l a r l y , the value f o r the experimental group (Fig. 133) i s 111.8 Kcal/Kg BW-75 according to the equation: Y = -.169 + .00151 X + 73.85 (p = .038). The above data indicate that the control group approaches maintenance sometime in August. At th i s time ambient temperature may range from 60 to 80°F. Under t h i s p a r t i c u l a r condition of range and feed type th i s group w i l l remain at maintenance or below for approximately seven months. As ambient temperature declines from p o s i t i v e to negative during the f a l l and winter, maintenance requirements for t h i s group w i l l gradually increase. In contrast, the experimental group, supported by better q u a l i t y alpine forage, does not approach maintenance u n t i l i t returns to the winter range around November. At t h i s time ambient temperature may be below freezing. As winter temperatures decline t h i s group remains at maintenance or s l i g h t l y below for approximately four to f i v e months. The establishment of a maintenance value f o r DE includes the energy contributed by DP since body weight change BODY WEIGHT CHANGE IN KG / DAY 6 6 6 6 268 cannot be a t t r i b u t e d to e i t h e r p r o t e i n or energy under the co n d i t i o n s of t h i s experiment but to a combination of both. I t i s p o s s i b l e to e s t a b l i s h a r e l a t i o n s h i p between the n i t r o g e n requirements of an animal and the DE s u p p l i e d during a y e a r l y c y c l e . Subsequently, when n i t r o g e n balance reaches zero approximately 1421.9 K c a l of DE i s r e q u i r e d f o r animals of the c o n t r o l group to maintain themselves, accord-i n g to the equation: Y = -5.349 + .003762 X + 489.7; p = .039. For the experimental group approximately 1062.1 K c a l of DE i s r e q u i r e d according to the equation Y = -4.27 + .00402X +1005.0, p = .0063. The adequacy of the q u a l i t y of the two d i e t s to supply n i t r o g e n to maintain n i t r o g e n balance i s seen i n the f o l l o w i n g r e l a t i o n s h i p s . For the c o n t r o l group eipproximately 2.8 percent CP i s necessary to r e t a i n n i t r o g e n balance at zero, according to the equation: I Y = -1.539 + .5489 X + 4.14; p = .0023. The experimental group r e q u i r e s 3.5 percent CP according to the equation: Y = -2.984 + .8470 X ± 4.672; p =• .0088. ; . A Comparison of the C o n t r o l and Experimental Groups on a  High Q u a l i t y Ration a f t e r being on Submaintenance Rations. The c o n t r o l and experimental groups of sheep were maintained on low q u a l i t y r a t i o n s throughout the w i n t e r of 1969-70 (October u n t i l A p r i l ) . At the end of t h i s p e r i o d an experiment was conducted to measure the response of these groups to a d i e t of improved q u a l i t y (CP t 20.38 percent; GE -r 4.380 Kcal/gm). A description of the d i e t i s given i n Table 49 (Appendix F ) . P r i o r to the experiment the control group was i n much poorer body condition than the experi-mental group as judged from coat condition, general appearance and differences i n body weight. This experiment attempted to simulate the natural cycle whereby animals change from low q u a l i t y over-wintered forage to high q u a l i t y spring growth. Also, i t was conducted to measure differences i n nitrogen and energy metabolism between groups of sheep i n d i f f e r e n t body condition a f t e r existence on submaintenance rations. Pre-viously, with the adult ewe group, a s l i g h t improvement i n dietary q u a l i t y during l a t e winter produced an increase i n nitrogen retention. This e a r l i e r experiment, i n contrast to that described above, was conducted to determine the e f f e c t of supplementing free ranging animals during the l a t e c r i t i c a l winter period. As shown in Table 50, the response of the experimental group was superior to that of the control group for a l l nutrient categories. This means that the dietary experience of a group of bighorns during the summer, was s t i l l to be seen i n improved adaptive capacity 5-6 months l a t e r . Average apparent d i g e s t i b i l i t y was approximately 3 percent higher, feed intake 291.46 grams per day greater, protein intake 57.99 grams per day greater, etc. The d i g e s t i b l e energy intake was approximately 1153.35 Kcal per day greater for the experimental group, and the d i g e s t i b l e protein to energy r a t i o , approximately 270 N u t r i t i o n a l Control Experimental Description Category Group Group of Units D i g e s t i b i l i t y 77 .66 80. 78 Percent Feed Intake 868 .39 1 ,159. 85 Gm/Day Protein Intake 177 .09 235. 88 Gm/Day Digestible Protein 126 .78 187. 23 Gm/Day Protein Balance 63 • 74 102. 40 Gm/Day Energy Intake 3,803 .58 5 ,069. 68 Kcal/Day Digestible Energy 2,927 .32 4 ,080 . 67 Kcal/Day Dig. Protein to Energy Ratio 44 .6 45. 8 Fecal Weight 194 .46 . 229. 71 Gm/Day Fecal Protein 50 .31 48. 65 Gm/Day Urine Protein 63 .04 84. 81 Gm/Day Fecal Energy 4 .518 4. 291 Kcal/gm Fecal Energy 876 .26 989 . 86 Kcal/Day Table 50. A comparison of the n u t r i t i o n a l parameters between the control and experimental groups while on ra t i o n 36-57, a f t e r being on submaintenance r a t i o n s . 271 1.2 units higher. In terms of nutrients l o s t i n the feces, the experi-mental group had a larger f e c a l weight per day but l o s t less protein than the control group. S i m i l a r l y , f e c a l energy i n Kcal per gram was lower for the experimental group but due to the larger f e c a l weights, energy losses i n Kcal per day were s l i g h t l y higher. In terms of absolute amounts of protein and energy retained, the experimental group i s far superior i n every category. Each nutrient category was also expressed i n terms of body weight and body w e i g h t a s Shown i n Table 51. Subsequently, when weight differences are minimized, the experimental group i s superior i n every category. Larger quantities of each nutrient are retained per kilogram of body 75 weight and per kilogram of body weight by the experimental group than by the control group. When f e c a l losses are expressed i n terms of body weight the experimental group loses less i n each nutrient category than does the control group. The difference i n condition between groups a f t e r e x i s t i n g on submaintenance rations throughout the winter i s d i r e c t l y a t t r i b u t a b l e to the influence of alpine forage. This influence i s c a r r i e d over to the following spring when the animals begin a new annual cycle, providing evidence that animals i n better condition are more e f f i c i e n t users of high N u t r i t i o n a l Category Per Day Control Kg Body Weight Group K g • 75 Body Weight''° Experimental Group Kg Kg Body Weight Body Weight''° Feed Intake 28.41 66.75 29.39 73.6 8 Protein Intake 5.07 13.61 5.98 14.98 Digestible Protein 4.14 9 .74 4.74 11.89 Protein Balance 2.08 4.89 2.59 6 .51 Energy Intake 124.46 292 .35 128.47 322.09 Digestible Energy 95.79 225.01 103.41 259.25 Fecal Weight 6.36 14.95 5.82 14.59 Fecal Protein 1.64 3.86 1.23 3.09 Fecal Energy 28.67 67.35 25.08 62.88 Table 51. A comparison of the control and experimental groups on rati o n 36-57, with each n u t r i t i o n a l category expressed i n terms of body weight and body weight*' 5, a f t e r being on submaintenance rations. 273 q u a l i t y spring forage. When placed on r a t i o n 36-57 the control group took i n 2040.20 (291.4 gm/day) grams less feed per 7 day period than the experimental group. Their d i g e s t i b i l i t y was only 3 percent l e s s . The experimental group took i n 2 8.62 grams per kilogram body weight and the control group 2 8.34. The s i m i l a r i t y between these feed intake values indicates that the above difference i n feed intake i n grams can be att r i b u t e d to the 21 pound difference' i n body weight between groups. According to the scale set up previously, values of 28 are s l i g h t l y above maintenance and should be associated with s l i g h t p o s i t i v e weight gains. The migratory group gained .43 LB/day and the non-migratory group .21 LB/day. The e f f e c t of p e l l e t i n g the r a t i o n and i t s stimulatory e f f e c t (by comparing c a l o r i c density) a f t e r the sheep had been on an extremely low qu a l i t y r a t i o n may have caused greater changes i n weight for a value of 28 gm/Kg BW than that obtained for roughages. I t i s therefore obvious that one r e a l advantage gained from a l t i t u d i n a l migration i s the a c q u i s i t i o n of a physical state better able to respond to n u t r i t i o n a l opportunities where they occur. Feed and Nutrient Intake per Year Yearly intakes of feed and nutrients were based on data obtained from digestion t r i a l s undertaken monthly except 274 for the period December through March 1969-70 when p a r t i c u -l a r l y severe weather intervened. Data from a t r i a l conducted i n late November served to represent conditions i n December through February. A t r i a l conducted i n A p r i l represented the period March through A p r i l . Total yearly feed and nutrient intake for the control and experimental groups i s expressed i n grams or Kcal per year, grams or Kcal per kilogram body weight per year and 75 grams or Kcal per kxlogram body weight per year, as shown i n Table 52. The improvement i n intake by the experi-mental group i s given i n Table 53. Yearly intakes were greater for the experimental group for each n u t r i t i o n a l category expressed i n each of the above ways. Gross feed intake (dry matter basis) d i f f e r e d by approximately 57,000 grams/year (Table 52) or 16.6 percent (Table 53). Thus, a y e a r l i n g animal on the winter range consumed about 620 pounds/year (281.1 kilograms) while one that migrated consumed about 744 pounds/year (337.4 kilograms), oven day weight. Feed intake differences are a consequence of increases i n average body weight differences between groups during the year as well as large differences i n nutrient content of the forage (which also determines feed intake) between the feed n a t u r a l l y available to the two groups of animals. Dramatic declines i n crude protein content of winter range forage (see Figure 7) during a yearly cycle and large N u t r i t i o n a l Category T o t a l Intake Per Year Control Group Experimental Group Intake Per Intake Per T o t a l Intake Intake Per Intake Per 75 . ., 75 Kilogram BW Kilogram BW* Per Year Kilogram BW Kilogram BW Feed Intake gm 281875.48 9060.61 21338.03 338200.15 Prot e i n Intake gm 16452.43 528.84 1245.44 31917.58 D i g e s t i b l e Protein gm 8450.72 271.64 639.72 19896.42 Protein Balance gm 3461.00 111.25 262.00 10338.92 Energy Intake Kcal 1186190.54 38128.91 89794.89 1407165.02 D i g e s t i b l e Energy Kcal 705154.59 22666.66 53380.36 898952.87 9402.28 887.34 553.14 287.43 39120.51 24991.74 23038.16 2174.22 1355.33 704.28 95855.93 61236.57 Table 52. A comparison of annual feed and n u t r i e n t intake between the con t r o l and experimental group, during 1969-70. - J Percent Difference Percent Difference Percent Difference N u t r i t i o n a l Category Between Groups, Between Groups/Kilo- Between Groups/Kilo-Total Intake gram BW gram BW* 75  Feed Intake 16.6 3.6 7.3 Protein Intake 48.4 40.4 42.7 Digestible Protein 57.5 50 .9 52.7 Protein Balance 66.5 61.2 62.7 Energy Intake 15.6 2.5 6 . 3 Digestible Energy 21.5 9.3 12.8 Table 53. The percentage increase i n feed and nutrient intake by the experimental over the control group, based on yearly t o t a l s . 277 differences i n crude protein content between summer and winter range forage produce large differences between groups at each stage of protein metabolism (Table 52). Since feed intake differences are only 16.6 percent i t i s l i k e l y that the major portion of the 48.4 percent dif f e r e n c e i n protein intake between groups can be a t t r i b u t e d to differences i n forage q u a l i t y . The d i f f e r e n c e between groups becomes greater at each stage of protein metabolism (Table 53). Feed intake expressed on a basis of body weight s i m i l a r to that for metabolic body weight, of course reduces the between-group differences while differences i n protein intake remain large (Table 53). The observed differences i n crude protein, d i g e s t i b l e p r o t e i n intake and protein balance are due to differences i n forage q u a l i t y more than to increased amounts of feed consumed. The experimental group becomes more e f f i c i e n t or the control group l e s s e f f i c i e n t in retention and conversion of protein as i t i s metabolized as demonstrated by a 48.4 per-cent difference at the ingested protein l e v e l which increases to a 57.5 and 66.5 percent difference at the d i g e s t i b l e and protein retention l e v e l , r e s p e c t i v e l y . Feed and nutrient intake for the experimental group has been par t i t i o n e d into three periods; pre-migratory, migratory and postmigratory. Each n u t r i t i o n a l category i s expressed i n : either grams or Kcal per period or per day per 278 75 period and m terms of BW and BW* as shown i n Tables 54, • 5 5 and 56. In each method of expression the migratory period i s superior i n supplying feed and nutrients as compared to the pre and postmigratory periods. In Table 54, feed intake i s expressed i n grams per day for each period but does not account for weight changes for the experimental group between the pre and postmigratory periods. In th i s instance, feed intake per day i s 87.45 grams greater during the post than the premigratory period. When feed intake per day i s expressed i n terms of BW (Table 55) or .75 BW (Table 56) i t i s greater during the premigratory than the postmigratory period. When the seasonal grouping periods are ranked i n descending order of qu a l i t y (protein and energy intake) they become migratory, premigratory and postmigratory. Animals of the experimental group are more e f f i c i e n t users of protein during the migratory than the premigratory period but u t i l i z e energy approximately the same during each period. Both periods are superior to the postmigratory period i n terms of e f f i c i e n t use of these nutrients. Period Feed Intake Pr o t e i n Intake D i g e s t i b l e Protein Protein Balance Energy Intake D i g e s t i b l e Energy Gra/Period Gm/Period Gm/Period Gm/Perio'd Kcal/Period Kcal/Period Premigratory 56459.21 6791.52 4979.22 2238.82 247694.05 173486.56' A p r i l 1-June 15 (742.88)+ (89.36) (65.51) (29.46) (3259.13) (2282.72) Migratory 14.3075.84 19815.41 June 16-Oct.l5 (1172.75) (162.41) 13954.47 (114.38) 8253.66 (67.65) 646721.44 (5300.99) 446889. 52, (3663.03) Postmigratory 138665.10 5310.65 0ct.l6-March 31 (830.33) (31.80) 962.73 (5.76) -76.07 (-.45) 512749.53 (3070.36) 278616.79 (1668.36) + ( ) Intake per day Table 54. The annual n u t r i e n t intake of the experimental group showing the co n t r i b u t i o n of the summer range forage between periods on winter range forage. to Period Feed Intake Protein Intake D i g e s t i b l e Protein Protein Balance Energy Intake D i g e s t i b l e Energy Gm/Kg BW Gm/Kg BW Gm/Kg BW Gm/Kg BW Kcal/Kg BW Kcal/Kg BW Premigratory 2209.75 265.81 194.88 87.62 9694.48 6790.08 A p r i l 1 - June 15 (29.07)+ (3.49) (2.56) (1.15) (127.55) (89.34) Migratory 3857.53 534.53 376.23 222.53 17436.54 12048.78 June 16-0ct. 16 (31.61) (4.38) (3.08) (1.82) (142.92 (98.76) Postmigratory 3477.08 133.16 24.14 -1.91 12857.34 6986.37 0ct.l6-March 31 (20.82) (.79) (.14) (-.011) (76.99) (41.83) + ( ) Intake per day. Table 55. The annual n u t r i e n t intake of the experimental group expressed i n terms of body weight, showing the con t r i b u t i o n of the summer range forage between periods on winter range forage. co Period Feed Intake Gm/Kg-75 P r o t e i n Intake D i g e s t i b l e Protein Protein Balance Energy Intake D i g e s t i b l e Energy Gm/Kg-75 Gm/Kg-75 Gm/Kg-75 Kcal/Kg- 75 K c a l / K g ' 7 5 Premigratory 4939.56 A p r i l 1-June 15 (64.99)+ 594.18 (7.82) 435.62 (5.73) 195.87 (2.57) 21670.52 (285.13) 15178.17 (199.71) Migratory June 16-Oct.l6 9519.35 (78.03) 1318.39 (10.81) 928.44 (7.61) 549.14 (4.50) 43029.37 (352.70) 29733.16 (243.71) Postmigratory 0ct.l6-March 31 8732.06 (52.29) 334.40 (2.00) 60.62 (.36) -4.79 (-.03) 32289.00 (193.34) 17545.13 (105.06) + ( ) Intake per day Table 56. The annual n u t r i e n t intake of the experimental group expressed i n terms of metabolic body weight, showing the co n t r i b u t i o n of the summer range forage between periods on winter range forage. to CO 2 8 2 Discussion and Conclusions This study dealt mainly with the q u a l i t a t i v e factors a f f e c t i n g the year long n u t r i t i o n of a wild ungulate. The n u t r i t i o n a l assessment of a migratory and nonmigratory group of bighorn sheep was based on an experimental determination of the q u a l i t y of winter and summer range forage associated with such c r i t e r i a as species composition, phenology, and forage moisture. A n u t r i t i o n a l assessment of winter and summer range forage has demonstrated that c e r t a i n quantitative and q u a l i t a t i v e aspects of the forages available to wild ungulates determines t h e i r s u r v i v a l during the c r i t i c a l winter period. Snowfall d e f i n i t e l y l i m i t s the a v a i l a b i l i t y of forage at c e r t a i n times throughout the winter. This factor was not simulated i n the present study but i t , i s well known that during severe winters, when animals must subsist on low q u a l i t y forages, the s u r v i v a l of a wintering animal i s greatly influenced by the number and degree of quantitative feed l i m i t a t i o n s . The l i m i t a t i o n s imposed by heavy snowfall produce a reduction i n density and species d i v e r s i t y of vegetation available on the winter range, physical a v a i l a b i l i t y of forage through the snowcover and increase the length of time an animal i s dependent upon th i s old growth for subsistence. The i d e a l s i t u a t i o n appears to be one where a portion of the bunchgrass along with other herbaceous species remain 283 standing throughout the w i n t e r to p r o v i d e a s u b s i s t e n c e r a t i o n . Remaining bunchgrasses should be f l a t t e n e d t o p r o v i d e the e a r l y emergence of s p r i n g growth. Knight (1970) found t h a t e l k p r e f e r r e d new s p r i n g growth fescue when i t c o n t a i n e d l i t t l e or no o l d growth. R e s u l t s from t h i s study i n d i c a t e t h a t a heavy overwinter s n o w f a l l can improve the apparent d i g e s t i b i l i t y o f dry matter of s p r i n g growth by about 19 p e r c e n t , w i t h subsequent improvements i n dry matter and n u t r i e n t i n t a k e . V a r i o u s f o r a g e mixtures (with and without bluebunch wheatgrass) were fed throughout the second win t e r t o a s c e r t a i n the importance of bluebunch wheatgrass i n the w i n t e r n u t r i t i o n of w i l d u n g u l a t e s . Q u a l i t a t i v e assessment of t h i s s p e c i e s i n d i c a t e t h a t i t d i d not supply more CP, GE or phosphorus or t h a t i t s i g n i f i c a n t l y improved d i g e s t i b i l i t y more than d i d the other grass m i x t u r e s when fed d u r i n g the w i n t e r . One of the most important f a c t o r s i n the annual c y c l e i s the t i m i n g of s p r i n g green-up. A c c o r d i n g to Steen (1968) the most c r i t i c a l time f o r r e i n d e e r i s u s u a l l y A p r i l and May, as l a t e w i n t e r and e a r l y s p r i n g are the weak l i n k i n the n u t r i t i o n a l c h a i n of the y e a r . In t h i s study area green-up may occur i n l a t e March or e a r l y A p r i l but has been observed i n r e s t r i c t e d areas under s p e c i f i c c o n d i t i o n s of s l o p e and aspect i n l a t e F e b r u a r y . In t h i s r e g a r d , K l e i n (1965) g i v e s an e x c e l l e n t d i s c u s s i o n of the many f a c t o r s governing f o r a g e q u a l i t y . Cook and H a r r i s (1950) d i s c u s s 284 s i t e f a c t ors. Costello and Price (1939) describe the c l i m a t i c and elevational e f f e c t s on plant development and range readiness. The observations of these authors are supported and i n some cases complimented by the present study. Spring green-up occurring at the above times provides approximately 3 months between growth of spring forage and p a r t u r i t i o n . In most years t h i s w i l l allow adequate intake of CP, GE, phosphorus etc., for t h i s most important phase of fo e t a l development. Several authors working i n the w i l d l i f e f i e l d have attempted to assess the protein requirements of deer for growth (Ullrey et a l . 1967, Wood et a l . 1962, French et a l . 1956) and reproduction (Murphy and Coates, 1966; Verme, 1962). Most studies have u t i l i z e d a r t i f i c i a l rations (ground and/ or pelleted) to produce d i e t s varying i n protein content, allowing them to determine protein requirements of 12-18 percent for optimum growth and reproduction. The monthly n u t r i t i o n a l measurements achieved i n t h i s study indicate that summer range forage plays an important r o l e i n the l a t e winter s u r v i v a l of bighorn sheep and i n the provision of nutrients necessary to maintain reproductive condition. Recent work on forage moisture indicates i t s pote n t i a l value (Turner, 1972) for range and animal n u t r i t i o n work. In t h i s study, forage moisture content was useful i n predicting the crude protein content of both winter and summer range forage. The constancy of change for t h i s nutrient 285 throughout a yearly cycle i n most grassland areas of North ' America should allow the development of pr e d i c t i v e equations using forage moisture. Other workers (Abrams, 1961; Watkins, 1943; Richards et a l . 1962) have rel a t e d growth stage to aspects of forage q u a l i t y . S p e c i f i c a l l y , Osbourn et al.(1966) show a s i g n i f i c a n t inverse c o r r e l a t i o n between the apparent digest-i b i l i t y of organic matter and the phenological time at which forage i s harvested. In my study, forage preference tests confirmed the importance of phenology i n forage s e l e c t i v i t y by wild ungulates. If phenological stages are ranked; with the e a r l i e s t growth having rank 1 and the dormant forage having rank 10 then a cumulative index of phenological stages for spring u n t i l f a l l w i l l undoubtedly show a s i g n i f i c a n t inverse r e l a t i o n s h i p with such aspects of forage q u a l i t y as CP. Throughout t h i s study i t has been evident that basic range measurements, e s p e c i a l l y those undertaken on spring-growth winter-range forage and summer-range forage, such as forage moisture, phenology and forage q u a l i t y can be used as accurate predictors of body condition, weight and general animal performance i f proper consideration i s given to the standardization of forage c o l l e c t i o n and measurement. The lack of t h i s type of assessment i n range studies involving wild ungulates has been noted by Geist (1972). Also, range measurements such as gross energy .content of the forage can be useful i n determining turn out dates for 286 c a t t l e on r a n g e s where c a t t l e a n d w i l d l i f e o v e r l a p o r compe'te. S e v e r a l s t u d i e s , n o t a b l y t h o s e o f T r l i c a and Cook ( 1 9 7 2 ) , Mooney and B i l l i n g s ( 1 9 6 0 ) , and McDonough (1969) have begun t o examine t o t a l and s o l u b l e c a r b o h y d r a t e c o n t e n t o f r a n g e p l a n t s w i t h t h i s i n m i n d . The s t u d y o f t h e n u t r i t i o n o f w i l d u n g u l a t e s i s r e l a t i v e l y new i n c o m p a r i s o n t o t h a t o f d o m e s t i c a n i m a l s • o r t o o t h e r s t u d i e s o f w i l d a n i m a l s . I n v i e w o f t h i s i t i s d i f f i c u l t t o d e v i s e v a l i d c o m p a r i s o n s among s t u d i e s . I n a g r e e m e n t w i t h B l a x t e r ( 1 9 6 2 ) , I have d e t e r m i n e d t h a t b i g h o r n sheep u n d e r v a r y i n g c o n d i t i o n s o f d i e t a r y t y p e , f o r m and q u a l i t y , r e q u i r e a d j u s t m e n t p e r i o d s o f a t l e a s t 12 d a y s and more r e l i a b l y 18 d a y s b e f o r e an a d e q u a t e a s s e s s m e n t o f a new f o r a g e c a n be made. D i e t z e t a l . (1962) u s e d o n l y 5 - 7 d a y a d j u s t m e n t p e r i o d s , and g i v e s d i g e s t i b i l i t y f i g u r e s t h a t a p p e a r low i n c o m p a r i s o n t o t h e f o r a g e q u a l i t y . S i m i l a r l y , e x t e n s i v e n u t r i t i o n a l s t u d i e s u n d e r t a k e n by U l l r e y e t a l . (1964, 1967 and 1968) on w h i t e - t a i l e d d e e r u t i l i z e d s i n g l e s p e c i e s d i e t s , m a i n l y , and s h o r t e r a d j u s t m e n t p e r i o d s t h a n t h o s e u s e d i n t h i s s t u d y . A g a i n , d i g e s t i b i l i t y f i g u r e s a r e n o t e n t i r e l y c o m p a r a b l e a c c o r d i n g t o t h e q u a l i t y o f t h e d i e t . O t h e r a u t h o r s h ave u s e d " i n v i t r o " t e c h n i q u e s (Bezeau and J o h n s t o n , 1 9 6 2 ) , u s i n g rumen i n n o c u l u m f r o m d o m e s t i c a n i m a l s . D i f f e r e n c e s i n t h e f e e d i n g r e g i m e between y e a r s p r o d u c e d d i f f e r e n c e s i n t h e u t i l i z a t i o n o f f o r a g e s b e t w e e n 287 groups of experimental animals. I t appears that the continuous feeding of natural forages throughout the year i s more conducive to digestion and rumen function than i s the s i t u a t i o n where di e t s are changed i n a prescribed pattern at short i n t e r v a l s . This factor should be considered i n future experimental n u t r i t i o n a l studies with wild animals. Under the regime of periodic dietary change provided to the adult ewe group, digestion averaged 3 8.2 percent and nitrogen balance became negative, when CP content declined to about 5 percent; while under the continuous feeding regime i t averaged approximately 55 percent when dietary q u a l i t y , composition and phenology were sim i l a r and nitrogen balance did not become negative u n t i l CP content of the d i e t reached 3.22 percent CP. Generally, under either feeding regime the measure-ment of animal performance indicates that high elevation forage (alpine and subalpine) i s superior to that from the winter range and equips the migratory animal with s u f f i c i e n t n u t r i t i o n a l reserves to supplement the feed avai l a b l e on the winter range so as to ensure s u r v i v a l during most winters. The migratory group u t i l i z e d winter range forage more e f f i c i e n t l y than did the control group during the winter months through improved d i g e s t i b i l i t y of dry matter, protein and energy. S i m i l a r l y , superior nitrogen balance demonstrated by t h i s group indicated i t s a b i l i t y to u t i l i z e low q u a l i t y 288 forages more e f f i c i e n t l y than c o u l d the c o n t r o l group d u r i n g c r i t i c a l w i n t e r p e r i o d s . However, a t t h i s time i t does not appear t h a t r e s e r v e s brought down from the summer range can adequately compensate f o r the p e r i o d s when u n u s u a l l y heavy s n o w f a l l s cause food l i m i t a t i o n s d u r i n g the c r i t i c a l w inter p e r i o d . I t was demonstrated by experiments from t h i s study t h a t an animal which can respond to a d e c l i n e i n dry matter d i g e s t i b i l i t y by t a k i n g i n l a r g e r q u a n t i t i e s o f feed b e n e f i t s g r e a t l y , through i n c r e a s e s i n n u t r i e n t i n t a k e , d i g e s t i b i l i t y and n u t r i e n t b a l a n c e . I n d i v i d u a l s w i t h t h i s a b i l i t y appear b e t t e r a b l e t o s u r v i v e under the harsh w i n t e r c o n d i t i o n s which occur on the wint e r range through more e f f i c i e n t u t i l i z a t i o n of summer range f o r a g e . Feed i n t a k e on the summer range w i l l be l i m i t e d by fo r a g e q u a l i t y and rumen c a p a c i t y but i t i s u n l i k e l y t h a t animals a b l e t o i n g e s t g r e a t e r q u a n t i t i e s of feed w i l l be l i m i t e d by the p h y s i c a l a v a i l a b i l i t y o f f o r a g e . Animal performance g e n e r a l l y depends on the q u a l i t y of the d i e t ( U l l r e y e t a l . 1967) which i n t u r n i n f l u e n c e s feed i n t a k e and apparent d i g e s t i b i l i t y . I found t h a t CP was the s i n g l e most s i g n i f i c a n t f a c t o r a f f e c t i n g the d i g e s t i b i l i t y of dry matter, feed i n t a k e and the i n t a k e and d i g e s t i b i l i t y of v a r i o u s n u t r i e n t s whereas GE e x h i b i t e d l e s s i n f l u e n c e on these n u t r i t i o n a l measurements. Waite e t a l . (1964) i n d i c a t e d the s i g n i f i c a n c e of the n i t r o g e n component of the feed when they 2 8 9 s u g g e s t e d t h a t t h e r e d u c e d n i t r o g e n s t a t u s o f a n i m a l s f e d s o l e l y o n g r a s s i n w h i c h b o t h t h e p r o t e i n c o n t e n t a n d p r o t e i n d i g e s t i b i l i t y a r e l o w , may r e s u l t i n s u b - o p t i m u m c o n d i t i o n s o f rumen f l o r a . The i m p o r t a n c e o f CP i n t h e r e g u l a t i o n o f t h e n u t r i t i o n o f b i g h o r n s h e e p was e x e m p l i f i e d t h r o u g h o u t t h e s t u d y u s i n g p r e d i c t i v e l i n e a r e q u a t i o n s . S i g n i f i c a n t r e l a t i o n s h i p s b e t w e e n CP and a l m o s t a l l o t h e r n u t r i t i o n a l m e a s u r e m e n t s ( d i g e s t i b i l i t y , f e e d i n t a k e , p r o t e i n f r a c t i o n s , e n e r g y f r a c t i o n s ) , e s p e c i a l l y f o r t h e m i g r a t o r y g r o u p , d e m o n s t r a t e d t h e c o n t r o l e x h i b i t e d b y t h i s n u t r i e n t w h i c h was n o t e v i d e n t f o r t h e r e g r e s s i o n s w i t h GE. I i n t e r p r e t my f i n d i n g o f t h e i m p r o v e d p e r f o r m a n c e o f t h e m i g r a t o r y g r o u p o f s h e e p as c o m p a r e d t o t h e n o n -m i g r a t o r y g r o u p when f e e d i n g u p o n t h e same w i n t e r r a n g e g r a s s e s , a s a r i s i n g f r o m t h e p r o t e i n s t o r e s a c c u m u l a t e d o n t h e summer r a n g e . The i m p o r t a n c e o f p r o t e i n r e s e r v e s i n t h e rumen h a s b e e n e x a m i n e d b y s e v e r a l w o r k e r s . The p r e c i s e r e l a t i o n s h i p b e t w e e n d i e t a r y n i t r o g e n a n d t h e t r a n s f e r o f n i t r o g e n f r o m rumen t o omasum h a s b e e n d e m o n s t r a t e d by G r a y e t a l . (1958) . F u r t h e r m o r e , Hogan e t a l . (1969) h a s r e v e a l e d t h a t up t o 47 p e r c e n t o f t h e rumen b a c t e r i a l p r o t e i n may p a s s t h r o u g h t h e g a s t r o i n t e s t i n a l t r a c t t o be u t i l i z e d b y t h e a n i m a l d u r i n g t h e p e r i o d on l o w q u a l i t y d i e t s . M c N a u g h t e t a l . (1954) d e m o n s t r a t e d t h e s u p e r i o r d i g e s t i b i l i t y o f b a c t e r i a l n i t r o g e n . S i m i l a r l y , i t i s s i g n i f i c a n t t h a t t h i s a d v a n t a g e g a i n e d 290 through migration can s t i l l be detected the following spring i n better u t i l i z a t i o n of feed and nutrients. The mechanism operating here appears s i m i l a r to that suggested by Klein and Sch^nheyder (1970) i n the deer species they studied. They demonstrated a n . a b i l i t y to compensate for low nitrogen levels i n the forage by re c y c l i n g nitrogen through the s a l i v a and further conservation of ruminal nitrogen by r e c y c l i n g i t through successive generations of the microbial population. The apparent a b i l i t y to compensate for v a r i a t i o n i n forage nitrogen l e v e l s i s limited when deer are on range of general poor q u a l i t y or during f a l l and winter when forage nitrogen lev e l s are reduced. In my study the continuous decline of forage CP from 20' to 2 percent placed nitrogen i n short supply i n terms of the GE a v a i l a b l e . In l a t e winter, forage GE remained above 4 Kcal/gm and DE averaged 43 and 52 percent, s i m i l a r to the apparent d i g e s t i b i l i t y of dry matter, for the control and experimental group while both DP and nitrogen balance became negative. Hungate (1966, pg. 318) states that " V a r i a b i l i t y i n d i g e s t i b i l i t y i s determined i n some cases by the crude f i b r e content and i n others by the nitrogen content. When the nitrogen content of the feed f a l l s below a protein equivalent of 5 percent, d i g e s t i b i l i t y diminishes." The discrepancy I have shown between the d i g e s t i b i l i t y of nitrogen and that for energy and dry matter suggests that an examination of the ava i l a b l e energy component of the t o t a l 291 GE may indicate a secondary control of d i g e s t i b i l i t y while animals subsist on low q u a l i t y forage. ./ The negative DP values demonstrated as applicable to a l l my experimental groups doubtless a r i s e from the same processes described by Mclntyre and Williams (1970). They suggest that when sheep are fed on low protein content diets the t o t a l amount of protein leaving the pylorus may be greater than the amount supplied i n the d i e t due to microbial synthesis of protein i n the rumen from endogenous nitrogen sources, p a r t i c u l a r l y urea. U l l r e y et a l . (1967, 1968) obtained negative DP values with white-tailed deer on diets of balsam f i r , cedar and 4ack pine. In my study, DP declined to negative values by late winter although f e c a l nitrogen showed minor v a r i a t i o n through-out the year. Robinson and Forbes (1970) found no s i g n i f i c a n t v a r i a t i o n i n f e c a l nitrogen output between treatments (7 -26 percent CP) while there was a l i n e a r increase i n urinary nitrogen output with increasing dietary N intake. S i m i l a r l y , Livingston et a l . (1967) and E l l i o t t and Topps (1963) working with low protein content d i e t s (4 to 5 percent CP) found that a progressive reduction i n CP content of the r a t i o n reduces the actual amount of urea nitrogen excreted. The decline i n urinary nitrogen output was due mainly to t h i s d e c l i n i n g output of urea. The urea retained appears to contribute to negative DP values i n l a t e winter. Thus, my findings are substantiated and explained by the relevant research on 2 9 2 domestic sheep. The wide range of CP values necessary to provide high p o s i t i v e weight gains as well as negative DP values appeared to be l i n e a r l y related to dietary CP over the range of CP studied. Robinson and Forbes (1970) suggest that there i s an increase i n nitrogen retention with increasing dietary nitrogen intake on a c u r v i l i n e a r r e l a t i o n s h i p when CP values ranged from 7 to 26 percent. More det a i l e d work on summer range forage alone may e s t a b l i s h a s i m i l a r r e l a t i o n s h i p . Supplementation of the winter range-diet from rumen reserves of b a c t e r i a l protein obtained while on the summer range i n combination with possible urea recycling are mechanisms designed to e f f i c i e n t l y conserve nitrogen. These processes are complemented by a reduction i n urine nitrogen during periods of low nitrogen a v a i l a b i l i t y . My r e s u l t s indicate that loss of urine nitrogen s t a b i l i z e d at 1.6 - 1.9 grams of nitrogen/day (equivalent of 10-12 grams/day of protein) for the adult ewe group and .8 - 1.4 grams/day of nitrogen for the yearling groups when the CP content of the forage f e l l below 6 percent. This apparent s t a b i l i z a t i o n appears to be supported by the work of E l l i o t t and Topps (1963) but was d i f f i c u l t to ascertain i n the work of Schmidt-Nielson et a l . (1957) or Livingston et a l . (1962). Urine nitrogen s t a b i l i z a t i o n should be examined i n more d e t a i l with wild ungulates 2 9 3 i n order to f u l l y understand the degree of urea r e c y c l i n g and associated benefits during periods of low dietary protein intake. A preliminary i n t e r p r e t a t i o n of body maintenance was conducted at various points throughout the study, p r i o r to the assessment using change i n body weight. F i r s t l y , feed intake for the control group increased throughout the spring and early summer while the CP content of the forage declined from 14 to 5 - 6 percent, a f t e r which feed intake began to decline. S i m i l a r l y , s t a b i l i z a t i o n of urine protein occurred when CP content of the forage f e l l below 6 percent. In terms of nitrogen balance the control group required 2.8 percent and the experimental group 3.5 percent CP to r e t a i n i t at zero. These l a t t e r figures appear low but i t must be understood that urea r e c y c l i n g was not accounted f o r . Consideration of the DE required for maintenance indicated that approximtely 1400 and 1100 Kcal/day were necessary for zero nitrogen retention by the control and experimental groups of sheep, resp e c t i v e l y . At zero body weight change approximately 2100 and 1600 Kcal/day are required for the respective groups. Measurements obtained during the seasonal cycle indicate that both groups approached these values sometime i n October and November (Oct. 9 -Control - 1609 Kcal/day; Experimental - 1510 Kcal/day). The DE requirements at zero nitrogen retention are somewhat 294 lower than those at zero weight change, but may be s l i g h t l y • altered by urea r e c y c l i n g . Ultimately, maintenance was determined at zero weight change. This method produced values (65.7 and 42.7 Kcal/Kg BW for the control and experimental groups respectively) s i m i l a r to those obtained by U l l r e y et a l . (1969 and 1972). Comparing these computed values to those a c t u a l l y obtained during the t r i a l s indicates that the control group reached maintenance by August while the migratory group reached maintenance sometime i n October during the change from summer to winter range forage. The DE maintenance requirements i n association with the monthly period when maintenance i s reached indicates that 5 - 6 percent CP i s required for the control group and approximately 4 - 5 percent for the experimental group. The various methods give somewhat variable r e s u l t s which should be checked under more cont r o l l e d conditions ( i s o c a l o r i c d i e t s , etc.) but generally indicate that pre-liminary i n t e r p r e t a t i o n of maintenance can be accomplished with feed and urine analysis. These data indicate that the DE values for maintenance along with the CP required to maintain zero nitrogen balance can be r e l a t i v e l y low. In each determination of maintenance, with the exception of the CP requirements at zero nitrogen retention, the experimental group required less DE and CP than did the 2 9 5 control group. It appears that the superior q u a l i t y alpine* forage provided rumen reserves as well as improving body condition (fat reserves) and coat development for the experimental group. Therefore, the maintenance requirements, which are p a r t i a l l y dependent on these factors are considerably l e s s . This finding i s supported by several e a r l i e r studies. U l l r e y et a l . , (1967) found that faster gaining fawns were more e f f i c i e n t and t h i s r e f l e c t e d the r e l a t i v e l y lower maintenance costs for fawns which reached weights i n a shorter period of time. S i m i l a r l y , Blaxter (1962) found that high q u a l i t y d i e t s with higher metabolizable energy are used more e f f i c i e n t l y for maintaining an animal. Comparisons of energetic e f f i c i e n c y between groups, i n t h i s study indicated the superior feeding regime of the migratory group; Several authors (Johnston & Bezeau, 196 2; Abrams, 1961) have noted the possible e f f e c t of vitamin shortage (especially carotene) when forage becomes dormant and cured. At the summer's end (September) while the experimental group was involved with the l a s t digestion t r i a l on alpine forage and the control group was being maintained on cured winter forage a multiple vitamin tonic was administered for a period of one week. Both groups responded with improvements i n apparent d i g e s t i b i l i t y , feed intake and body weight gain i n proportion to d i e t a r y q u a l i t y . This type of p o s i t i v e response indicates that there may be an actual vitamin shortage i n 296 the forage avai l a b l e to an ungulate grazing on the range. Al t e r n a t e l y , the deficiency may be attributed to methods used while preserving harvested forage. Crampton and Harris (1956) f e e l that a deficiency of vitamin A may occur where there i s a late spring, e s p e c i a l l y on grass type ranges. However, they suggested that c a t t l e and sheep b u i l d up important vitamin reserves i n t h e i r l i v e r during the summer when they graze on succulent green forage. The succulent, a c t i v e l y growing alpine range forage probably contributes s i g n i f i c a n t quantities of vitamin A to migratory ungulates. In t h i s study feed consumption on a dry matter basis varied from 3.3 percent of l i v e body weight for the experimental group on alpine forage to 1.9 percent on overwintered forage during the post-migratory period. I t changed from 2.2 to 2.8 to 2.0 percent of l i v e body weight for the control group during the seasonal sequence of pre-migratory, migratory and post-migratory periods. The improve-ment i n feed intake shown by the experimental group under-going migration i s expressed i n large part i n superior body weight gains. These figures are within the range determined by Halls (1970) for range livestock and some big game animals. The examination of t o t a l dry matter intake serves to i n t e r r e l a t e most facets of t h i s study because i t i s influenced by nutrient and water content of the forage, water i n t a k e , p a l a t a b i l i t y , body weight and ambient temperature. The mechanisms regulating food intake have been adequately 297 examined by Balch and Campling (1962) who demonstrated the importance of the rate of disappearance of digesta from the reticulorumen and by Baile and Mayer (1970) who reviewed the chemostatic and physiologic controls. In t h i s study, several factors (forage q u a l i t y , body weight, ambient temperature, etc.) were operative at the same time i n th e i r control of dry matter intake. The influence of any single factor was d i f f i c u l t to determine or c o n t r o l . For example, during the summer when ambient temperature exerted a minimal e f f e c t , feed intake was shown to increase i n association with increases i n body weight while forage q u a l i t y (CP) declined to 6 percent CP. This resulted i n a two phased curve for the control group (Fig. 26) and a three phased curve for the experimental group (Fig. 13 - showing the CP - GE r e l a t i o n s h i p ) . Although under the influence of body weight change these curves indicated that the control of feed intake i n wild ungulates should be examined seasonally. In Figure 13, body weight exerts a greater influence i n early spring and summer than i n late summer and f a l l . When body weight i s accounted for (feed intake/Kg BW) the d i r e c t l i n e a r r e l a t i o n s h i p of feed intake and forage q u a l i t y (CP) i s evident f o r both the control and experimental group. Blaxter et a l . (1961) has shown that feed intake increases with increasing s i z e of sheep si m i l a r to that shown 298 i n Figure 55 of t h i s study. This r e s u l t was evident i n t h i s study even though forage q u a l i t y was d e c l i n i n g over the range of body weights shown i n Figure 55. There are c o n f l i c t i n g statements i n the l i t e r a t u r e regarding the r e l a t i o n s h i p between feed intake and forage q u a l i t y and the c l o s e l y related r e l a t i o n s h i p between feed intake and apparent d i g e s t i b i l i t y . Jones (1972) c i t e s evidence that both these r e l a t i o n s h i p s are c u r v i l i n e a r with feed intake d e c l i n i n g both on high q u a l i t y - highly d i g e s t i b l e forage and on low q u a l i t y - poorly digested forage. My studies support the findings of Blaxter et a l . (1961) that 73 dry matter intake/Kg body weight" and apparent d i g e s t i b i l i t y increased with feed q u a l i t y , as dry matter intake was greater when hay of good q u a l i t y was compared to that of medium qu a l i t y . The r e s u l t s obtained from the experiments conducted i n my study may not extend over the entire range of feed intake, d i g e s t i b i l i t y or q u a l i t y u t i l i z e d by Jones (1972) since many of the r e s u l t s he reviewed used pelleted concentrates. More det a i l e d work on the summer range may lead to a c u r v i l i n e a r r e l a t i o n s h i p i n d i c a t i n g possible chemoregulatory and p h y s i o l o g i c a l mechanisms determining voluntary.intake. I t i s not l i k e l y , at l e a s t under the conditions of t h i s study, that voluntary water intake affected the voluntary dry matter intake. This i s supported by work of Campling (1964). The amount of water occurring n a t u r a l l y i n fresh 299 forage taken from the f i e l d was approximately equal to that ingested when the animals were fed a i r dried forage. Considering the range of dietary types and t h e i r composition i t appears l i k e l y that differences i n p a l a t a b i l i t y play an important r o l e i n determining feed intake during the various seasons. P a l a t a b i l i t y differences were p a r t i a l l y reduced by feeding a l l forage on an a i r dried basis. However, the large improvement i n the feed intake of summer range forage could be at t r i b u t e d to enhanced p a l a t a b i l i t y of t h i s forage type over and above that produced by vegetative q u a l i t y and body weight change. It i s well known that animals respond to cold below a s p e c i f i c threshold (Graham et a l . 1959) by increasing energy intake provided the digestive q u a l i t i e s of the feed (CP, energy, fibre) permit the digestive t r a c t to process more feed. During the winter months feed intake for a l l groups of sheep was s i g n i f i c a n t l y influenced by minimum ambient temperature (Balch and Campling, 1962). U l l r e y et a l . (1970) note a s i g n i f i c a n t c o r r e l a t i o n of .68 between weekly mean temperature and weekly feed intake when the average weekly temperature was below freezing 7 out of 9 weeks. S i m i l a r l y i n t h i s study, the animals i n both groups responded to declining ambient temperature, beginning at approximately 32°F but es p e c i a l l y so at -20°F, by increasing feed intake. This occurred even though the o v e r a l l e f f e c t of d e c l i n i n g feed q u a l i t y was to produce measurable p a r a l l e l declines i n 300 apparent d i g e s t i b i l i t y and feed and nutrient intake between October and A p r i l . As mentioned previously, i n d i v i d u a l s which, under ce r t a i n conditions, can increase t h e i r feed intake at the expense of d i g e s t i b i l i t y , tend to improve t h e i r t o t a l nutrient intake. The period of increased feed intake persisted longer for the control group (compensatory period) than for the experimental group during a s i m i l a r decline i n ambient temperature. That the experimental group did not undergo a compensatory period was at t r i b u t e d to the b e n e f i c i a l e f f e c t s of summer range forage. This appears to substantiate the findings of Moose et a l . (1969) who showed that environ-mental temperature affected feed intake of lambs receiving low concentrate diets more than lambs receiving high concentrate d i e t s . Many people have expressed t h e i r views on sharp changes i n d i e t encountered by ungulates during the period they change from overwintered forage to succulent spring growth as well as the change they often undertake during winter feeding. The accepted theory, and that supported by data from the a g r i c u l t u r a l industry, suggests that t h i s change i s achieved with an ease and e f f i c i e n c y that depends upon the body condition of the animal and the rumen reserves i t harbours. In the present study, the d i e t for both groups of sheep was changed sharply from overwintered low q u a l i t y forage (2 percent CP) to the high q u a l i t y p e l l e t e d r a t i o n 36-57 301 (20 percent CP). At t h i s time the animals were i n r e l a t i v e l y -poor c o n d i t i o n (coat c o n d i t i o n , blood parameters: BUN, hematocrit, hemoglobin). The sharp change i n d i e t had no apparent harmful e f f e c t s on the sheep (with the exception of 2 l i g h t cases of d i a r r h e a ) . Both groups of sheep were fed ad l i b i t u m (1 to 3 pounds/day o f f e r e d , depending on the stage of intake) but ingested only 2-3 ounces/day f o r the f i r s t few days w h i l e g r a d u a l l y i n c r e a s i n g t h e i r i n t a k e over the next two weeks. Bighorn sheep, respond to abrupt changes i n t h e i r d i e t by prompt a l t e r a t i o n of t h e i r feed i n t a k e , thereby a s s u r i n g proper rumen adaptation. Two ounces of r a t i o n 36-57 provided them w i t h more CP than d i d 1.5 pounds of t h e i r n a t u r a l d i e t c u t i n February and March. The above data i n d i c a t e that bighorn sheep responded p o s i t i v e l y to an improved d i e t . An e a r l i e r experiment demonstrated t h a t a s l i g h t i n c r e a s e i n CP (1 percent) produced dramatic changes i n apparent d i g e s t i b i l i t y and n u t r i e n t i n t a k e . An increase of 1 percent CP provided an inc r e a s e of DP of .33 6 gm/Kg BW f o r the c o n t r o l group and .297 GM/Kg BW f o r the experimental group. By comparison, the present experiment showed t h a t the migratory group, being h e a v i e r , can i n g e s t l a r g e r absolute amounts of feed, and thus p r o t e i n , when the opp o r t u n i t y a r i s e s . However, as shown above the smaller animals i n the c o n t r o l group appear to be s l i g h t l y more e f f i c i e n t i n u t i l i z i n g an improved p r o t e i n supply when CP has been i n short supply. This f i n d i n g suggests that w i l d l i v i n g animals on a low p r o t e i n 302 d i e t could perhaps be better served by the provision of urea as a supplement rather than feeding hay or other a r t i f i c i a l supplements. Hobson (1969) i s experimenting with t h i s approach. This research has examined the hypothesis that the widespread habit of seasonal a l t i t u d i n a l migration dem-onstrated by most stocks of wild bighorn sheep conveys s i g n i f i c a n t n u t r i t i o n a l advantages upon the migrants. I have shown that the consequences of seasonal migration can be demonstrated by improved feed intake, apparent d i g e s t i b i l i t y , nitrogen and energy metabolism and e f f i c i e n c y . The t o t a l consequence can be seen i n the more rapid growth of the migrants, which revealed greater body size at a given point i n time. This does not mean that the non-migratory group might not achieve s i m i l a r sizes and weights eventually by prolonging the years of growth. In f a c t , compensatory growth was shown to occur during the second year i n the male yearling that had previously experienced a sub-maintenance r a t i o n for 6 to 8 months. In addition, the migrants demonstrated improved n u t r i t i o n a l performance when both groups were fed on the i d e n t i c a l winter range forage of low CP and GE content. This can be anticipated to provide the migrant group an improved capacity to survive the periods of winter malnutrition. An important c a l c u l a t i o n that could be substantiated by these r e s u l t s i s the establishment of carrying capacity values for t h i s winter range as well as associated ranges. Where forage y i e l d data are available from ranges with 303 r e l i a b l e estimates of animal numbers (sex and age composi-ti o n and body weights from the l i t e r a t u r e or the actual range) i t i s possible, using yearly or monthly feed intake figures, to estimate carrying capacity. The accuracy could be improved by modifying t o t a l y i e l d with food habit studies as well as using feed intake on a body weight basis. Where there are several ungulate species coexisting on a range, feed intake figures calculated on a metabolic body weight basis should be used to substantiate the v a l i d i t y of interspecies comparison. It w i l l be necessary i n future studies of t h i s type to p a r t i t i o n the GE measurement into i t s energy components (to t a l and soluble carbohydrate, crude f i b r e , c e l l u l o s e , l i g n i n , e t c . ) . It w i l l then be possible through multiple regression analysis to evaluate the importance of each protein and energy component. Undoubtedly, one of the most important contributions made by t h i s study i s the development of p r e d i c t i v e l i n e a r equations. Recently Harris et a l . (1971) reviewed t h i s topic and described the function of l i n e a r equations i n predicting nutrient r e q u i r e m e n t s , d i g e s t i b i l i t y , and as a method that has a p p l i c a t i o n i n solving p r a c t i c a l n u t r i t i o n problems. The usefulness of predicting various n u t r i t i o n a l parameters from basic range data (forage moisture, CP, energy) has previously been demonstrated. The development of f e c a l 3 0 4 nitrogen equations shows promise i n estimating feed and I nutrient intake of free ranging animals as well as assessing the general body condition of an i n d i v i d u a l or herd of grazing ungulates. This study emphasizes the importance of the length of time animals can spend on alpine forage and demonstrates the pronounced e f f e c t t h i s has on the d i g e s t i b i l i t y of dry matter and nutrients and on feed intake. High p o s i t i v e weight gains associated with the alpine d i e t established conclusively the combined p o s i t i v e influence of a l l facets (quality, p a l a t a b i l i t y , a v a i l a b i l i t y ) of t h i s vegetation. Body composition studies would provide i n t e r e s t i n g backup information to my study. My r e s u l t s strongly suggest that the influence of alpine forage was not e n t i r e l y r e s t r i c t e d to the summer period during which the forage was a v a i l a b l e . The high q u a l i t y alpine forage continued to exert i t s influence for a period of 1 to 2 months during the change from summer to winter range forage (late October to early December), i n the form of continuing gains i n weight. This occurred despite the fac t that the q u a l i t y of the winter range forage appeared inadequate to sustain t h i s change i n weight. I t seems probable that the l e v e l of nutrients a v a i l a b l e i n summer range forage provides the animal with reserves of protein that can be u t i l i z e d during the change to winter range forage as supple-mentary to and supportive of the d i r e c t d ietary intake. 305 In the f a l l , the change i n forage type for the experimental migrant group produced a sharp decline i n almost a l l n u t r i t i o n a l measurements, temporarily bringing them below those for the control group. By midwinter the migratory group had adapted to the winter range d i e t and greatly improved i t s n u t r i t i o n . I t i s u n l i k e l y that such a sharp change occurs i n the wild, at least i n the majority of years; rather, the change i n d i e t would be gradual and would promote a period of adjustment. The r e s u l t would be to maintain d i g e s t i b i l i t y measurements at lev e l s s l i g h t l y higher than those obtained i n t h i s study. 306 SUMMARY 1. The phenomenon of a l t i t u d i n a l migration, a feature common to the majority of ungulates throughout the Rocky Mountain Trench of southeastern B.C., was examined for i t s n u t r i t i o n a l benefits to migratory animals from the spring of 1968 through 1970. 2. Three groups of captive bighorn sheep were main-tained for various periods of time during the study, allowing n u t r i t i o n a l measurements to be made by the t o t a l c o l l e c t i o n method. 3. The captive sheep were fed natural grass d i e t s f o r 12 month periods in an attempt to simulate a non-migratory population of sheep which would.remain on the winter range as v/ell as a migratory population which would receive winter and summer range forage at s p e c i f i c seasons. 4. Approximately 6 tons of forage were s e l e c t i v e l y cut each year of the two year study. 5. ' The formulation of d i e t s was accomplished using information from f i e l d s e l ection t r i a l s with an imprinted sheep i n the lamb and yearling classes along with pen sele c t i o n t r i a l s which evaluated s e l e c t i o n between i n d i v i d -ual species and forage mixtures as well as se l e c t i o n between similar species i n d i f f e r e n t phenological stages. 6. Yearly p r e c i p i t a t i o n related to the amount of 307 snowfall and p a r t i a l l y to the l e v e l of forage moisture. • Forage moisture was useful i n pr e d i c t i n g the crude protein content of winter and summer range forage while the difference i n snowpack between years produced differences i n the proportion of old to new growth i n a standing bunch, with resultant differences i n apparent d i g e s t i b i l i t y and nutrient intake. 7. Qu a l i t a t i v e range measurements (CP, GE, phosphorus) were conducted throughout the year i n order to assess monthly changes in selected n u t r i t i o n a l components (nutrient intake, DP, DE, nitrogen balance). These measurements were i n turn correlated with more commonly measured features of range forage: species composition, forage moisture and phenology. A l l q u a l i t a t i v e and quantitative range measurements were c a r r i e d out on summer and winter range forages i n order to give a preliminary estimate of the n u t r i t i o n a l advantages encountered by a migratory band of bighorn sheep. 8. Subalpine and alpine range forage contained 17 to 11 percent CP, 4.47 to 4.40 Kcal/gm GE and 3000 to 1300 ppm phosphorus during the.migratory period when winter range contained only 7.2 to 3.4 percent CP, 4.3 to 4.16 Kcal/gm GE and 1500 to 800 ppm of phosphorus. 9 . Samples of summer range forage c o l l e c t e d between November (9 percent CP) and May 18 the following spring (7 percent CP) indicated that nutrients are preserved 308 in a l p i n e range forage throughout the winter due to freezing. This undoubtedly occurs on the winter range but to a much lesser degree. 10. Rumen adaptation to dietary change was established at about 12 to 15 days by the maximal feed intake method of Blaxter (1961) . 11. During the f i r s t year of the study the presentation of a dietary sequence for a si n g l e group of sheep pro-ceeded from the pellet e d r a t i o n 3 6-57 to alpine forage and f i n a l l y to three winter range forage mixtures d e c l i n i n g in q u a l i t y . This simulated the change from early growth spring forage, of a generally high q u a l i t y , to alpine forage, followed by the return to low q u a l i t y winter range forage. 12. This portion of the study further elucidated the benefits accruing from a l t i t u d i n a l migration previously demonstrated by the forage analysis. Feed intake declined from 1058 to 910 grams/day, apparent d i g e s t i b i l i t y of dry matter declined from 83 to 38 percent, protein intake from 210 to 44 grams/day, DP from 174 to -2.72 grams/day, nitrogen balance from 14 grams/day to an unmeasured negative value in la t e winter, ingested energy from 5240 to 4028 Kcal/day and DE from 4608 to 1741 Kcal/day during the seasonal change i n forage type from r a t i o n 36-57 and alpine forage to low qu a l i t y winter range forage. Estimations of energetic e f f i c i e n c y during changes i n 309 dietary q u a l i t y and composition provided s u f f i c i e n t evidence to support the contention that spring growth winter range forage along with alpine range forage were superior in the n u t r i t i o n a l e f f e c t s they produced when compared to winter range forage i n a si m i l a r or l a t e r phenological stage. 13. Trends i n feed intake data changed when the crude protein content of the forage f e l l below 6 percent, approximately. S i m i l a r l y , the CP content of the urine appeared to s t a b i l i z e at 11 to 12.6 grams/day regardless of decline i n the CP content below 7 percent. 14. Urinary protein was the major source of protein loss at higher l e v e l s of CP intake whereas f e c a l protein acted as the major source of protein loss at lower l e v e l s of CP intake, aft e r urine protein had s t a b i l i z e d . 15. During the c r i t i c a l l a t e winter period the captive animals were given an improved natural grass d i e t con-ta i n i n g approximately 1 percent more CP but si m i l a r in c a l o r i c content. Improvements i n apparent d i g e s t i b i l i t y and nutrient intake demonstrated that supplementation of wintering animals with s p e c i f i c nutrients may be a f e a s i b l e method of winter feeding. 16. Subsequently, i t was calculated that nitrogen became the l i m i t i n g factor i n l a t e winter i n proportion to the amount of energy. 17. I t appears l i k e l y then, that supplementation of 310 wintering animals with cheap nitrogen sources such as urea blocks may be more f e a s i b l e than u t i l i z i n g expensive winter feeding practices often demanded by the public. 18. The quantitative and q u a l i t a t i v e assessment of summer and winter range forage along with the preliminary n u t r i t i o n a l assessment of the benefits of a l t i t u d i n a l migration prompted a closer look at t h i s phenomenon using two groups of sheep, for purposes of comparison. The non-migratory or control group, comprised of two yearling females, u t i l i z e d winter range forage year round. The experimental group simulating the migratory pattern, comprised of two yearling females and a male, was changed from spring growth winter range forage to summer range forage and then back to winter range forage. 19. N u t r i t i o n a l benefits a t t r i b u t a b l e to alpine range forage were noted during t h i s part of the study as being of a greater magnitude than e a r l i e r measurements had indicated. 20. Alpine range forage contributed to improved yearly n u t r i t i o n by increasing feed intake by 19 5.4 gm/day, apparent d i g e s t i b i l i t y by 15.6 percent, ingested protein by 114.2 gm/day, DP by 93.63 gm/day, nitrogen balance by 51.2 percent, ingested energy by 1260 Kcal/day and DE by 1431 Kcal/day during the migratory period over that taken i n by the control group on winter range forage. 21. During the entire period the experimental group was 311 on alpine forage i t was calculated that they took i n 9363 grams of DP and 14 3,100 Kcal of DE more than did the control group. 22. Voluntary feed intake measured under an ad libitum feeding regime was p a r t i a l l y determined by forage q u a l i t y , body weight, p a l a t a b i l i t y , ambient temperature and species composition. Throughout the year, absolute feed intake produced a two phased curve for the experimental group. This indicated that future studies should provide a d e t a i l e d assessment of feed intake by season. Feed intake increased with the size of the animals but over a one year period body weight had a greater influence during the spring and summer than during the f a l l and winter. Similar d e t a i l e d studies of t h i s control factor should be conducted at seasonal i n t e r v a l s . "? 23. Feed intake, during the f a l l and winter months, was influenced by ambient temperature below 32° F. I t appeared that animals i n poorer condition, due to a poorer n u t r i -t i o n a l regime, exhibited compensatory feed intake during periods of r i s e i n ambient temperature a f t e r severe cold s p e l l s . 24. Voluntary water intake changed with the q u a l i t y of the d i e t , e s p e c i a l l y the DE component, but at no time did i t appear that the a v a i l a b i l i t y of water would l i m i t feed or nutrient intake. 25. In t h i s feeding regime, with the yearling groups, as 312 with the previous one, with the adult ewes, urine protein losses s t a b i l i z e d ( 5 - 9 gm/day) at l e v e l s of CP below 6 percent. 26. I t became evident that the period of rapid weight accretion began during spring green up on the winter range (a f l e x i b l e period between l a t e March and early A p r i l ) and continued throughout the period the experimental animals were on alpine forage, approximately 8 months. Alpine forage probably freezes around l a t e September in most years while s t i l l containing adequate quantities of CP (9 percent) and energy. Certain populations of bighorn sheep remain on alpine ranges year round and i f s u f f i c i e n t quantities of forage are available the improved qua l i t y over that of conventional winter range forage should aid i n t h e i r s u r v i v a l . 27. Changes i n body weight were used to estimate body maintenance requirements. Thus, DE requirements for maintenance are 65.7 Kcal/Kg BW and 42.4 Kcal/Kg BW f o r the control and experimental groups of sheep, re s p e c t i v e l y . These values become 156.3 Kcal/Kg BW'75 and 111.8 Kcal/Kg 75 BW for the respective groups when the maintenance requirments vary with metabolic weight. At zero nitrogen balance approximately 1421.9 and 1062.1 Kcal of DE are required. To improve the accuracy of these figures maintenance values should be calculated separately for each season. 28. The lower maintenance requirements of the experimental group were at t r i b u t e d to t h e i r superior coat condition, body condition i n the form of f a t reserves and rumen reserves which allowed more e f f i c i e n t u t i l i z a t i o n of forage. The period on summer range forage was the ultimate factor i n providing improved body form and condition. 29. Throughout the winter the experimental group digested 13 percent more forage than did the control group on s i m i l a r winter range forage as a r e s u l t of the influence of summer range forage. 30. In l a t e winter (1970), both groups were given the high q u a l i t y p e l l e t e d r a t i o n 36-57 to simulate the change from extremely poor q u a l i t y winter range forage to succulent high q u a l i t y spring growth. The experimental group was superior i n every n u t r i t i o n a l category measured i n d i c a t i n g the r e s i d u a l p o s i t i v e benefits of alpine forage given 8 months previously. 31. Feed and nutrient intake figures calculated on a yearly basis demonstrated that the control group required 281.1 Kg of feed/year while the experimental group ingested 337.4 Kg/year on a superior feeding regime. The migratory group received 17 percent more feed, 58 percent more DP and showed a 67 percent improvement i n protein balance on a yearly basis due to the influence of the summer range forage. These figures may serve as the basis for developing a carrying capacity model for t h i s range as well as other sim i l a r winter ranges. 314 32. Throughout the study p r e d i c t i v e l i n e a r equations • were e s t a b l i s h e d to f a c i l i t a t e f i e l d assessment of feed and n u t r i e n t i n t a k e . Thus, forage moisture appears u s e f u l i n e s t i m a t i n g CP content of the forage. S i m i l a r l y , p h e n o l o g i c a l growth stage may be c o r r e l a t e d w i t h n u t r i e n t content. The CP and GE content appear u s e f u l f o r purposes of p r e d i c t i n g feed and n u t r i e n t i n t a k e , DP, DE, n i t r o g e n balance and apparent d i g e s t i b i l i t y . Ambient temperature i s s i g n i f i c a n t l y r e l a t e d to feed in t a k e while water i n t a k e can be used to estimate energy i n t a k e . 33. Although CP was d e f i n i t e l y more u s e f u l than GE i n the p r e d i c t i o n of s p e c i f i c n u t r i t i o n a l parameters, the p a r t i t i o n i n g of t o t a l GE i n t o i t s f u n c t i o n a l components ( t o t a l and s o l u b l e carbohydrates, f i b r e , etc.) may provide f u r t h e r i n s i g h t i n t o the r o l e of energy i n the year long n u t r i t i o n of a w i l d animal. 34. F e c a l n i t r o g e n l i n e a r r e g r e s s i o n equations were developed f o r purposes of p r e d i c t i n g feed and n u t r i e n t i n t a k e , e t c . 35. The d i g e s t i b l e p r o t e i n to energy r a t i o has been c o r r e l a t e d w i t h maintenance and optimum growth f o r domestic animals. 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D ' i g e s t . i b l e a n d m e t a b o l i z a b l e e n e r g y r e q u i r e m e n t s f o r w i n t e r m a i n t e n a n c e o f M i c h i g a n w h i t e - t a i l e d d o e s . J . o f W i l d l . Mgmt. 3 4 ( 4 ) : 863-869. U l l r e y , D. E . , W. G. Y o u a t t , H. E . J o h n s o n , A . B . Cowan, R. L . C o v e r t , a n d W. T. M a g e e . 1972. D i g e s t i b i l i t y a n d e s t i m a t e d m e t a b o l i z a b i l i t y o f a s p e n b r o w s e f o r w h i t e -t a i l e d d e e r . J . o f W i l d l " . Mgmt. 36 (3) : 885-891. 324 Verme, L. J . 1962. Mo r t a l i t y of white-tailed deer fawns i n r e l a t i o n to n u t r i t i o n . Proc. 1st N a t l . White-tailed Deer Disease Symp. 1:15-38. Univ. Georgia, Athens. Waite, R., Margaret J . Johnston and D. G. Armstrong. 1964. The evaluation of a r t i f i c i a l l y d r i ed grass as a source of energy for sheep. J . Agric. S c i . 62:391-398. Wasser, C. H. 1940. Memorandum on food habits of bighorn sheep i n Rocky Mountain National Park. On f i l e , O f f i c e of Chief Park Ranger, Rocky Mountain National Park. Colorado. 3p. Watkins, W. E. 1937. The calcium and phosphorus contents of important New Mexico range forages. Ag r i . Exp. Sta. of the New Mexico College of Agriculture and Mechanic Arts . State- College, N. M. Tech. B u l l . 246. 75pp. Watkins, W. E. 1943. Composition of range grasses and browse at varying stages of maturity. New Mex. Agric. Exp. Sta. B u l l . 311. Watkins, W. E., and J . H. Knox. 1945. The monthly protein and phosphorus contents of two important range grasses i n southwestern New Mexico. J. of An. S c i . 4 (3):297-305 . Wilson, A. D. 1969. A review of browse in the n u t r i t i o n of grazing animals. • J . of Range Mgmt. 22 (11) :23-28. Wilson, R. K., and R. A. McCarrick. 1966. Apparent dry matter d i g e s t i b i l i t y , voluntary food intake and y i e l d s of dry matter of mixed swards, conserved as a r t i f i c a l l y dried grass and tetrapod hay, at progressive stages of maturity. Proc. 10th Int. Grassland Cong. 371-379. Wood, A. J . , H..C. Nordan, and I. McT. Cowan. 19 61. The care and management of wild ungulates for experimental purposes. J . W i l d l . Mgmt. 25(3);295-302. Wood, A. J . , I. McT. Cowan and H. C. Nordan. 1962. P e r i o d i c i t y of growth in ungulates as shown by deer of the genus Odocoileus. Can. J . Zool. 40 (4) :593-603. Wood, A. J... 1964. Early weaning and growth of the pig. Proc. XI. Int. Congr. Nutr. 89-99. E. and S. Livingston, Edinburgh. Wood, A. J . , and I. McT. Cowan. 1969. Post natal growth. From, A p r a c t i c a l guide to the study of the productivity of large herbivores. Ed. F. B. Golley and H. K. Buechner. Blackwell S c i e n t i f i c Publications. Oxford, England. APPENDIX A SCIENTIFIC AND COMMON NAMES FOR PLANT SPECIES CITED REFERENCES INCLUDE: FOREST SERVICE (1937), HERMANN (19 HITCHCOCK (1950), HUBBARD (1969) AND LYONS (1952). GRASS AND SEDGE: Agropyron spicatum Bromus tectorum Calamagrostis rubescens Elyitius glaucus Festuca idahoensis Festuca s c a b r e l l a Koeleria c r i s t a t a Poa pratensis Poa secunda Stipa columbiana Carex 2 spp. FORBS: A c h i l l e a m i l l e f o l i u m A c h i l l e a spp., Agoseris spp. Allium cernuum Anaphalis margaritacea Antennaria rosea Aster spp. Astragalus miser Balsamorhiza s a g i t t a t a Chrysopsis v i l l o s a Collomia grandiflora Epilobium alpinum Epilobium angustifolium Epilobium minutum Fragaria glauca Fragaria v i r g i n i a n a Hieracium Linum perenne Lomatium macrocarpum Monarda f i s t u l o s a Phlox hoodii Polygonum douglassi Senecio canus Thalictrum occidentale Tragopogon dubius T r i f o l i u m BROWSE: Amelanchier a l n i f o l i a Apocynum bluebunch wheatgrass downy chess pine grass blue wild-rye Idaho fescue rough fescue June grass Kentucky bluegrass Sandberg bluegrass Columbia needlegrass sedge common yarrow yarrow mountain-dandelion nodding onion pearly everlasting rosy pUssytoes aster milkvetch balsamroot golden aster collomia fireweed fireweed fireweed strawberry strawberry hawkweed fl a x b i s c u i t r o o t horsemint phlox ragwort meadow rue goatsbeard clover serviceberry dogbane 327 Arctostaphylos uva-ursi Artemisia f r i g i d a Populus tremuloides Pseudotsuga menziesii Purshia t r i d e h t a t a Rosa V7oodsii Spirea b e t i f o l i a Symphoricarpus albus bearberry s i l v e r sagebrush quaking aspen Douglas f i r antelope bitterbrush rose spirea snowberry APPENDIX B SPECIES COMPOSITION OF TWO WINTER RANGES IN THE EAST KOOTENAY Description Plant Species* Pl o t L-2 Canopy Cover/Freq. of Occurrence Pl o t L-3 Canopy Cover/Freq. of Occurrence Agropyron spicatum 55 .4/100.0 54 .1/100.0 Bromus tectbrura 4 .1/ 32 .5 t / 2.5 Grasses Koeleria c r i s t a t a 13 .3/ 87.5 t / 2.5 A c h i l l e a m i l l e f o l i u m 3 • 3/ 35.0 .8/ 5.0 Chrysopsis v i l l o s a 5 • 6/ 42.5 -Collomia gr a n d i f l o r a 3 • 4/ 30 .0 t / 2.5 Forbs Epilobium minutum 4 • 6/ 70.0 t / 2.5 Linum perenne 2 • 2/ 25.0 •2 • 7/ 32.5 Tragopogon dubius t / 2.5 3 .5/ 27.5 Amelanchier a l n i f o l i a - 7 .0/ 27.5 Shrubs Artemisia f r i g i d a 2 • 4/ 35 .0 14 • 1/ 67.5 Purshia t r i d e n t a t a 21 • 9/ 55 .00 2 .9/ 20.0 Symphoricarpus albus — 10 .0/ 67.5 Ground Cover Vascular plants 61 percent 54 percent L i t t e r 19 percent 22 percent Bare ground 19 percent 24 percent * C o l l e c t e d by B. C. Fish and W i l d l i f e Branch Table 15 The percent canopy coverage and frequency of occurrence for two s i t e s i n the Agropyron - Pursia community of the B u l l River Area, on steep slopes where no domestic grazing occurs. Description Plant Species* Canopy Cover/Frequency, of Occurrence WF 1 WF 2 WF 3 Agropyron spicatum 21/85 •38/100 38/100 Grass Festuca idahoensis 7/57 3/17 4/33 Koeleria c r i s t a t a 18/100 19/93 23/97 A c h i l l e a m i l l e f o l i u m 5/50 1/5 t/5 Allium cernuum 1/13 2/27 2/30 Fragaria v i r g i n i a n a • - 1/7 5/25 Forbs Lomatium macrocarpum 10/83 7/70 9/83 Monarda f i s t u l o s a t 7/70 5/57 Phlox hoodii 1/20 2/45 1/33 Polygonum douglassi - 1/30 1/13 Senecio canus 1/10 5/70 1/30 Trees and Shrubs Pseudotsuga menziesii t/3 t/3 t/3 Rosa woodsii 9/75 13/73 7/60 Ground Cover Vascular Plants 45 35 46 L i t t e r 13 12 12 Bare ground 10 5 3 Cryptograms 33 49 40 Elev a t i o n 3300 3200 3200 Slope n i l n i l n i l Aspect. n i l n i l n i l * C o l l e c t e d by the B.C. Fish and W i l d l i f e Branch Table 16 The percent canopy coverage and frequency of occurrence for three s i t e s on the Wigwam winter range. APPENDIX C SPECIES COMPOSITION OF THE NATURAL DIETS FED DURING 1968-70 Date Forage Cut Area Species Composition of Diet Percent Composition August 5-8 Kootenay Base Alpine Area Grass and Sedge Forbs Poa spp. Elymus glaucus 80.81 Carex 2 spp. Thalictrum occidentale A c h i l l e a spp. Anaphalis margaritacea 17.19 Fragaria glauca Epilobium angustifolium Agoseris spp. Browse Table 19. A des c r i p t i o n of the diets fed to the adult ewe group during 1968-69. Date Forage Cut Area Species Composition of Diet Percent Composition June 6 B u l l River Winter Range Grass Forbs Browse Agropyron spicatum Festuca spp. Koeleria c r i s t a t a 92.6 2.0 3 2.4 July 2 4 Wigwam Winter Range Grass Forbs Browse Agropyron spicatum 95 2 2 July 20 Premier Ridge Grass Forbs Browse Agropyron spicatum 94 4 2 July 24 Wigwam Winter Range Grass Forbs Poa pratensis Misc. grasses T r i f o l i u m spp. 93 2, 4 Table 19 Cont. Date Forage Species Composition of Percent Cut Diet Composition Comments A p r i l 15-20 Agropyron spicatum 50 s p e c i f i c a l l y Festuca spp. 40 selected for bunch-Calamagrostis rubescens 6 grass and fescue. Stipa spp. 3 Balsamorhiza s a g i t t a t a and 1 Spirea May 10-15 Agropyron spicatum 67.1 Festuca spp. 7.5 Calamagrostis rubescens 16.3 Balsamorhiza s a g i t t a t a 8.2 Amelanchier & Spirea .9 May 15-25 Agropyron spicatum 78 Festuca spp. 12.4 s e l e c t i v e l y cut Calamagrostis rubescens 4.3 to contain no Amelanchier, Spirea and Apocynum 5.3 . sunflower Table 20 A des c r i p t i o n of the composition of the winter range diets fed to the control group during 1969-70 and to the experimental group (A p r i l - J u l y and October to March). OJ OJ Date Forage Cut Species Composition of Diet Percent Composition Comments July 1-7 July 10-20 and August 10-20 Sept. 15-20 Agropyron spicatum Grass Festuca spp. Calamagrostis rubescens Koeleria c r i s t a t a Forbs Balsamorhiza s a g i t t a t a A c h i l l e a spp. Browse Amelanchier a l n i f o l i a Spirea Grass: s i m i l a r mixture as above Forbs: Browse: • " "• " " Grass: Forbs: Browse: ) 88.12 7 .14 4.74 88.1 7.2 4.7 90.0 7.0 3.0 cut with s i c k l e mower cut with s i c k l e mower fo r both t r i a l s . cut with s i c k l e mower Table 20 Cont. CO Date Forage Cut Area Species Composition of Diet Percent Composition Comments Oct. 9 Premier Grass Agropyron spicatum Ridge other grasses Forbs mainly Balsamorhiza Browse 50.0 45.0 4.0 1.0 cut with s i c k l e mower Oct. 10 Oct. 20-25 March 6-30 Premier Ridge , Wigwam Premier Ridge Grass Mixture: Calamagrostis rubescens Koeleria c r i s t a t a , Stipa spp., Festuca spp. no Agropyron Forbs Balsamorhiza & A c h i l l e a Browse Amelanchier and Spirea Kentucky bluegrass Forbs and misc. grasses Browse Symphoricarpus Grass Agropyron spicatum Misc. grasses Forbs Browse 90.1 6.8 3.1 92 2 5-10 50 4 5 1 2 3 Table 20 Cont. co CO cri Date of C o l l e c t i o n Area Plant Composition of Diet Percent Composition Remarks June 10-17 Kootenay Base-Subalpine Grasses 31 .55 (Preliminary period) Sedges 24 .55 Forbs: Fragaria, A c h i l l e a 29 .56 Browse 14 .14 July 1-7 Kootenay Base Subalpine Grasses and sedges 48 .98 Forbs 40 .00 Browse 11 .02 Grasses and sedges 34 .35 Forbs 60 .85 Browse 4 .80 July 10-15 Kootenay Base Alpine Grasses 37 .45 Sedges 11 .84 Forbs 50 .71 Sample one Sample two Table 21 The composition of the summer range diets fed to the experimental group during 1969. LO CO -J Date of C o l l e c t i o n Area Species Composition of Diet Percent Remarks Composition 10-20 Kootenay Base Aug. 20 -26 Grasses and Sedges 45 .8 Sample 1 Alpine Forbs 35 .7 Grasses 28 .9 Sedges 38 .1 Sample 2 Forbs 33 .0 23 Kootenay Base Sept. 23 -29 Grasses and Sedges 75 Fed Sept. Alpine Forbs:Fragaria & Epilobium 25 23 ,24 ,25,26 & 1/2 of 29 Grasses 95 Fed 27,28, & Sand Creek Forbs 5 1/2 of 29 Table 21 Cont. u> APPENDIX D PLANT NUTRIENT RELATIONSHIPS GROSS ENERGY CONTENT IN KCAL / GM c PI PARTITIONED GROSS ENERGY IN KCAL/GM O ro *3 0 3 3" 3 (0 <D rt H P, iQ n p->< IS tr i-C O 01 rt O rf p- 3 H-O rt O .3 (!) 3 3 a O i t ? H> P-o *o rt tn 3- cr [0 * (t H- rt O 3 S n r t o C ID O a t 3 ID i-l rt 13 Oi •S n 3 ro 0 iQ rt ro o ro n P- tli c 3 o o. ti ro 3- 0) a <a TJ in ro i o tr * rt ro 3* ro ro ro p-3 3 3 01 rt &i ro y 3 •a ro a a Pi ro *Q o> 3 n rt ro o ro n oi . Qj«£ 01 • •< n o xi c a m u oi. g o —I m M 2 n 5 H m 2 ?1 6 6 6 8 .8 341 2-0 4-0 G«0 8-0 10*0 IE'0 14*0 16-0 18-0 CRUDE PROTEIN CONTENT IN PERCENT FIGURE 13 . The re l a t i o n s h i p between crude protein and gross energy for winter.and summer range forage cut during 1969-70 for the experimental group. X = Premigratory, Y = Migratory, Z = Postmigratory* 4.50+ Y = 4.122 + .0042 X + 5.7 + 2-0 6-0 10'0 14-0 IB'O 32-0 CRUDE PROTEIN CONTENT IN PERCENT FIGURE 15. The r e l a t i o n s h i p between the crude p r o t e i n and".gross energy c o n t e n t o f w i n t e r and summer range f o r a g e when the energy c o n t r i b u t i o n o f the crude p r o t e i n has been removed. APPENDIX E ESTIMATION OF THE PERIOD OF ADJUSTMENT TO THE EXPERIMENTAL DIETS I 1150 1100 o I £ 10501 - 1000 Q LU LU i 950 >• z _ l o > UJ o < a: LU 900 850 800 750 FIGURE 18. (2 DAY AV.) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 TIME IN DAYS The average d a i l y voluntary feed intake of winter range grass cut June 6 for three adult ewes, using two day averages. 1250 Q 1200 & 1150i 2 1100 LU Lu >. 1000 cc 2 950| Z> _ J 9 > 900j UJ O g 850I LU 5 (2 DAY AV.) "6 8 10 12 14 16" TIME IN DAYS 18 20 22 24 FIGURE 19, c u t J u l v a ! ? ^ i 1 ^ 0 ^ 1 1 ^ ^ f e S d i n t a k S ° f W i n t e r range grass cut July 24 for three adult ewes, using two day averages! 346 APPENDIX F THE APPROXIMATE COMPOSITION OF RATION 36-5 7 347 Percent of Component Pounds per Ton Ration Ground Wheat 285 14.25 Ground Corn 600 30.0 Bran 245 12.25 Soybean (48.5%) 150 7.50 Fishmeal (72%) 110 5.50 Bone Meal 20 1.0 Grass Meal 200 10.0 Salt (100) 20 1.0 Molasses 150 7.50 Beet Pulp 200 10.00 Vitamin A (10) • 5 .025 Chromic Oxide 20 1.0 TOTAL 2000 .5 100.025 Table 49. The approximate composition of r a t i o n 36-57. APPENDIX G PLANT NUTRIENT - FEED INTAKE RELATIONSHIPS 1 1 0 0 . 0 + loao.ol FIGURE 40 . The r e l a t i o n s h i p between average feed i n t a k e and d i g e s t i b l e p r o t e i n . 1 1 0 0 . 0 . 1 0 4 0 . 0 . . ! 1 0 5 0 - 0 . . j 1 0 0 0 . 0 . . 9 8 0 - 0 . . 3 5 0 . 0 . . Y = 450.6 + 122.1 x + .328 P = .136 4 . 0 4 . 1 4 . 5 4 . 3 4 . 4 4 . 5 4 . 6 4-7 4*6 DROSS ENERGY IN THE FEED IN KCAL / GM FIGURE 41. The relationship between feed intake and gross energy i n the feed. . 5 . 0 1100.0.1. 1 1 0 0 . 0 DIGESTIBLE ENERGY IN KCAL / DAY DIGESTIBLE PROTEIN TO ENERGY RATIO FIGURE 4 3. The relationship between feed intake and apparent di g e s t i b l e energy. FIGURE 4 4. The relationship between feed intake and the digestible protein to energy r a t i o . APPENDIX H A MEASUREMENT OF FORAGE QUALITY, INTAKE, ANIMAL PERFORMANCE AND URINARY AND FECAL LOSSES FOR AN IMPROVED DIET. Measurement o f Forage Q u a l i t y , Intake and Animal Performance Value U n i t s Crude P r o t e i n 5.87 Perce n t Gross Energy 4.26 Kcal/gram D i g e s t i b i l i t y 68.5 Pe r c e n t Feed Intake 804.53 +37.1 Grams/Day Feed Intake 12.6 + .56 Grams/Kilogram Ingested P r o t e i n 47.23 Grams/Day D i g e s t i b l e P r o t e i n 26.41 Grams/Day Pe r c e n t D i g e s t i b l e P r o t e i n 55.92 ; Per c e n t N i t r o g e n Balance 17.21 Gm.N/7 Day 2.46 Gm.N/Day 107.59 Gm.CP/7 Day 15.37 Ingested P r o t e i n / C r u d e P r o t e i n i n Feed 8.0 DP (Gm/7 Day)/CP i n feed 31.7 N. Retained/Gin. o f i n g e s t e d N. .33 N.Retained/Kg Body Weight „ .0 38 N.Retained/Kg Body Weight" .107 Ingested Energy 3427.01 Kcal/Day D i g e s t i b l e Energy 2325.60 Kcal/Day P e r c e n t DE 6 7.93 Pe r c e n t Ingested Energy (Kcal/Day)/GE i n forage 804.4 DE (Kcal/Day)GE i n forage 545 .9 DP (Gm.)/DE i n Meal. 11.35 Table 57. A summary o f forage q u a l i t y , i n t a k e ewe group was p l a c e d on an improved and animal performance when d i e t d u r i n g the l a t e w i n t e r the a d u l t o f 1968-69. CO cn co Measurement of Urinary and Fecal Losses Value Units Fecal Weight Fecal Protein Fecal Protein(Percent of Ingested CP) Gm. of Fecal CP/Gm. of Feces Urine Volume Urine Protein Percent Protein i n Urine Urine CP (Percent of Ingested CP) Urine CP (Percent of DP) Fecal Energy Fecal Energy (Percent of Ingested GE) 256 20 44 ,20 ,82 .08 ,081 Gm/Day Gm/Day 570 11 4 23 41 ,6 03 72 35 76 Ml/Day Gm/Day 1101.41 32.14 Kcal/Day Table 58. A summary of urinary and f e c a l losses of protein and energy when the adult ewe group was placed on an improved d i e t during the l a t e winter of 1968-69. CO Ln 355 APPENDIX I ENERGY METABOLISM GOOO'GU. acoo-a GROSS ENERGY CONTENT IN KCAL / GM FIGURE 91. The r e l a t i o n s h i p between gross energy c o n t e n t o f the w i n t e r and summer range forage and i n g e s t e d energy f o r the e x p e r i m e n t a l group. 

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