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Performance of sheep raised in confinement, with special emphasis on their nutritional requirements Bryant, Ronald George 1972

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PERFORMANCE OF SHEEP RAISED IN CONFINEMENT WITH SPECIAL EMPHASIS ON THEIR NUTRITIONAL REQUIREMENTS by RONALD GEORGE BRYANT B.Scr.(Agr.) UNIVERSITY OF BRITISH COLUMBIA, 1970  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIEKCE i n the Department of Animal Science We accept t h i s t h e s i s as conforming t o the required standard  THE UNIVERSITY OF BRITISH COLUMBIA December, 1972  In presenting this thesis i n p a r t i a l fulfilment 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 freely available for reference and  study.  I further agree that permission for extensive copying of this thesis for scholarly purposes may by his representatives.  be granted by the Head of my Department or  It i s understood that copying or publication  of this thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission.  Department of  ANIMAL SCIENCE  The University of B r i t i s h Columbia Vancouver 8, Canada  ABSTRACT  Four main experiments were c a r r i e d out to study the n u t r i e n t r e quirements and management of sheep r a i s e d i n confinement. Experiment I was designed to study the reproductive performance and p r o t e i n u t i l i z a t i o n of ewe lambs bred to lamb a t approximately 14 to 16 months of age.  Rapeseed meal was compared to soybean meal as a source  of supplemental p r o t e i n d u r i n g the second h a l f of g e s t a t i o n .  Ewe weight  gains and lamb b i r t h weights were not a f f e c t e d by e i t h e r the l e v e l or the source of p r o t e i n .  Neither d r y matter nor p r o t e i n d i g e s t i b i l i t y were i n -  fluenced by the stage of g e s t a t i o n of the ewe.  No c o n s i s t e n t r e s u l t s were  obtained with regard to n i t r o g e n r e t e n t i o n of the ewes d u r i n g the l a s t h a l f of g e s t a t i o n .  The r e s u l t s suggest t h a t 11$ crude p r o t e i n (CP) i n the dry  matter supplying approximately 6 8 g d i g e s t i b l e crude p r o t e i n (DCP) may be adequate f o r t h i s c l a s s of ewes.  The r e s u l t s also i n d i c a t e d t h a t a l e v e l  of 2 2 $ rapeseed meal may be included i n the d i e t of g e s t a t i n g ewes without producing g o i t r o g e n i c or other adverse e f f e c t s . Experiment I I was conducted to assess the performance of ewe lambs during l a c t a t i o n when fed rapeseed meal or soybean meal together w i t h low q u a l i t y roughage.  Weight changes of the ewes and the average d a i l y gain of  the lambs over the eight week l a c t a t i o n period were not a f f e c t e d by the l e v e l or the source of p r o t e i n .  The r e s u l t s suggest t h a t 1 0 $ CP i n the dry matter  supplying approximately 92 g DCP may be adequate f o r the c l a s s of ewe studied.  A l e v e l of 2 5 $ rapeseed meal may be included i n the d i e t o f l a c -  t a t i n g ewes. I n Experiment I I I wheat and b a r l e y were compared as energy sources i n a l l - c o n c e n t r a t e r a t i o n s f o r lambs weaned at e i g h t weeks of age.  The  c e r e a l grains were fed i n the whole, r o l l e d , and p e l l e t e d forms together  ii with a pelleted protein supplement. Digestiblity t r i a l s were also conducted to measure the digestibility of energy and protein as influenced by grain, process and level of intake. rate of lambs fed wheat or barley.  There was no difference i n growth  Whole grains resulted in a faster rate  of gain than the pelleted form. Digestibility of energy was not influenced by the method of processing.  Protein digestibility was similar for the  whole and rolled grains with a tendency for pelleting to depress digesti b i l i t y of this nutrient.  Increasing feed intake from maintenance to  appetite resulted i n a slight depression i n nutrient d i g e s t i b i l i t y .  The  results of this study suggest that processing of cereal grains for lambs i s unnecessary from the standpoint of d i g e s t i b i l i t y and would appear to be detrimental i n terms of growth rate and feed conversion efficiency. Experiment IV was designed to study the influence of level of protein supplementation of whole barley based rations for early weaned lambs.  A series of digestibility studies were conducted to measure the  digestibility of dry matter and protein during three periods of growth. Results of this study demonstrated that 1 6 $ CP i n the ration of lambs from 2 0 - 2 9 kg liveweight was sufficient to produce the most economical gain during this period of growth.  In the period from 2 9 - 36 kg the  lambs receiving 1*$ CP i n the ration gained faster and had the best feed conversion efficiency.  During the f i n a l finishing period the results  suggest that one could continue to feed a 1*1$ CP ration. The digestibility of dry matter and crude protein were not influenced by stage of growth of the animal.  iii TABLE OF CONTENTS  Chapter  Page  A  INTRODUCTION  1  B  LITERATURE REVIEW  3  1.  3  Ewes 1.  Nutrient requirements and u t i l i z a t i o n during 3  pregnancy (a) Protein requirement f o r maintenance.  2.  . .  3  (b) P r o t e i n requirement f o r pregnancy . . . .  k  (c) P r o t e i n requirement of ewe lambs  8  Nutrient requirements and u t i l i z a t i o n during 10  lactation (a) E f f e c t of n u t r i t i o n during gestation on l a c t a t i o n performance  . . . .  10  (b) P r o t e i n requirement i n r e l a t i o n t o milk production  •  •  (c) Milk y i e l d and composition • 3.  . . . . . . . . . .  Suckling Lambs 1.  Feeder Lambs 1.  22  22  Rations f o r creep feeding lambs and t h e i r intake  HI.  19  Nutrient requirements from b i r t h t o eight weeks o f age  2.  16  Use o f rapeseed o i l meal and low q u a l i t y roughage . . .  II.  13  23 2k  Performance of lambs f e d a l l concentrate rations  2k  iv  Chapter  Page 2.  Digestibility of a l l concentrate rations . .  29  3.  Level of protein i n a l l concentrate rations  30  (a) Effect of breed, sex, and preweaning management on protein requirements . .  35  k. Rumen development of lambs fed a l l 36  concentrate rations « . . . IV. C  MATERIALS AND METHODS I.  II. III. D  Experimental Methods and Chemical Analysis . . . .  kZ  General Methods  k2  1.  Experimental Design  k2  2.  Feeding Trials  3.  Digestibility Trials  .  **5 **9  Chemical Analyses Statistical Analyses  50  EXPERIMENTAL I.  39  Reproductive performance and protein u t i l i z a t i o n of ewe lambs bred to lamb at approximately 1^-16 months of age and fed rapeseed o i l meal and low 50  quality roughage  II.  1.  Introduction *  2.  Materials and Methods  3.  Results and Discussion  50 .  50 52  Performance of ewe lambs during lactation when fed rapeseed meal and low quality roughage . . .  57  V  Chapter  Page  III.  1.  Introduction  57  2.  Materials and Methods  57  3.  Results and Discussion  59  The influence of energy source and physical form of a l l concentrate rations for early weaned lambs .  6k  1.  Introduction  6k  2.  Materials and Methods  66  3.  Results and Discussion  69  (a) Lamb performance  ......  71  (b) Digestibility of grains IV.  69  The influence of level of protein supplementation of whole - barley based rations for early 78  weaned lambs . .  E  1.  Introduction  78  2.  Materials and Methods  78  3.  Results and Discussion  8°  SUMMARY  Qk  BIBLIOGRAPHY APPENDIX  I  .  . . . . . . . . .  86  A comparison of the performance of mature ewes suckling single or twin lambs and fed two levels of energy and a constant level of protein  100  1.  Introduction  100  2.  Materials and Methods  100  3*  Results and Discussion  103  vi  Chapter APPENDIX  Page I I A comparison of mature ewes suckling single lambs when fed two levels of protein at a constant  III  IV  V  level of energy intake  105  1.  Introduction  105  2.  Materials and Methods  105  3.  Results and Discussion  106  Digestibility of Rapeseed and Soybean meals » . .  109  1.  Introduction  109  2.  Materials and Methods . ,  109  3.  Results and Discussion  109 112  Milk Production and Composition 1.  Materials and Methods  2.  Results and Discussion  Statistical Analysis-Tables  .«  112 112 115  vii LIST OF TABLES Table  Page  1-1  Composition of concentrate supplements  1-2  Ewe performance  52  1-3  Digestibility and nitrogen balance  $h  I-k  Nitrogen retention  55  II-l  Composition of concentrate supplements  58  II-2  Ewe and lamb performance and creep feed consumption (pregnancy and lactation treatment) . .  II-3  ...51  . . . . 60  Ewe and lamb performance and creep feed consumption (lactation treatment only)  III-l  Composition of supplement  IH-2  The main treatment effects of grain and process on average daily gain, feed conversion, and feed intake  III-3  71  72  The influence of level of feed intake and method of processing on nutrient digestibility  III-6  69  Nutrient d i g e s t i b i l i t y coefficients for the main treatment effects  III-5  67  Lamb performance as influenced by wheat and barley i n three physical forms  III-4  6l  75  The effect of grain and process on dressing percentage and certain rumen characteristics  76  viii  Table IV-1  Page Levels of protein i n the r a t i o n during three periods of growth  IV-2  79  The e f f e c t of the l e v e l of p r o t e i n during three periods of growth on the average d a i l y gain and feed conversion . .  IV-3  The e f f e c t of l e v e l of p r o t e i n over the entire feeding period on the average d a i l y gain and feed conversion r a t i o  IV-4  81  82  Nutrient d i g e s t i b i l i t y c o e f f i c i e n t s - four treatments at three periods of growth  »*..  83  ACKNOWLEDGMENTS A sincere and great expression o f thanks i s extended to Dr. R.M„ Tait, for the continual guidance, consultation and help received through the duration of this study. The writer also wishes to extend thanks to Dr. WJ). Kitts, Professor and Chairman of the Department of Animal Science for making available a l l the required departmental f a c i l i t i e s . I am also grateful to my fellow students for: their constructive suggestions and valuable assistance.  INTRODUCTION Lamb meat i s faced w i t h i n c r e a s i n g competition from other meats and there are i n d i c a t i o n s t h a t the present l e v e l of consumption r e f l e c t s a r e l a t i v e d e c l i n e i n demand f o r lamb as consumption of other r e d meats increases.  A p a r t i c u l a r a t t r a c t i o n to lamb production i s that even w i t h  i n t e n s i v e systems i n v o l v i n g r e l a t i v e l y u n s o p h i s t i c a t e d winter housing, a r e l a t i v e l y small proportion of the t o t a l c a p i t a l i n the e n t e r p r i s e i s i n vested i n f i x e d equipment.  I n t e n s i f i c a t i o n of sheep production must be  examined i n t h i s context.  Mechanization i n the sheep i n d u s t r y has been  slow; while the use of confinement, or semiconfinement management systems, labour saving equipment, and s p e c i a l l y constructed housing has increased r a p i d l y i n the production of c a t t l e , p o u l t r y , and swine.  Confinement  r e a r i n g o f sheep presents the opportunity t o use labour saving equipment, and t o i n t e n s i f y production,.  Harvesting and feeding forage from h i g h l y  productive t i l l a b l e land w i l l r e s u l t i n more complete u t i l i z a t i o n and greater production per acre than when lambs are pastured.  Confinement  feeding increases ease of handling, feeding, and c o n t r o l of p a r a s i t e s . I t removes f a c t o r s associated with weather and p r o t e c t s against predators. Lambs tend to f i n i s h more evenly and slow developing lambs are more e a s i l y identified. The b i o l o g i c a l and economic e f f i c i e n c y of lamb production i s dominated by the resources r e q u i r e d to maintain the breeding ewe. fed  i n confinement can be f e d according t o t h e i r needs.  Ewes  However, proper  n u t r i t i o n of the ewe and lamb may be more c r i t i c a l under these c o n d i t i o n s . S a n i t a t i o n w i l l be more c r i t i c a l since a l l o w i n g a disease t o s t a r t under these c o n d i t i o n s could l e a d to i t s r a p i d spread.  Confinement a l s o presents  2 the opportunity to make use of new knowledge about e s t r u s synchronization and superovulation as methods of i n c r e a s i n g the number of lambs born per ewe per year.  By i n c r e a s i n g the o v e r a l l e f f i c i e n c y and lambing percentage,  the sheep producer w i l l be able to help meet the ever i n c r e a s i n g operating costs of the sheep e n t e r p r i s e . The experiments reported h e r e i n were conducted t o study the performance of sheep r a i s e d under t o t a l confinement conditions with s p e c i a l emphasis on t h e i r n u t r i t i o n a l requirements, using feeds r e a d i l y a v a i l a b l e to sheepmen i n B r i t i s h Columbia.  3 B  LITERATURE REVIEW  I. 1.  EWES  N u t r i e n t requirements and u t i l i z a t i o n d u r i n g pregnancy Brody (19^5) from a comprehensive  study of the n i t r o g e n r e q u i r e -  ments of d i f f e r e n t species i n d i c a t e d t h a t the maintenance requirement o f  • 73 non - pregnant sheep was 3.6 g DCP/kg W*  daily.  This corresponds t o an  intake o f approximately 60 g DCP f o r $0 kg ewe and i s s i m i l a r t o the NRC (1957) recommendation o f approximately $k g DCP f o r ewes o f the same weight.  These values are i n close agreement t o those suggested f o r ewes  i n e a r l y g e s t a t i o n ( P h i l l i p s o n 1959 and Thomson and A i t k e n 1959). F o r ewes i n the l a t e r stages o f g e s t a t i o n a requirement o f 120 g DCP per day f o r 50 k g ewes has been accepted f o r many y e a r s . (a)  P r o t e i n requirement f o r maintenance There i s evidence that the maintenance requirement may be con-  s i d e r a b l y lower than t h a t suggested by Brody, (19^5).  E a r l y r e s u l t s pre-  sented by H a r r i s and M i t c h e l l (19^1) showed t h a t approximately 23 g DCP d a i l y may be adequate t o maintain n i t r o g e n e q u i l i b r u m i n 50 kg non — pregnant ewes. Robinson and Forbes (±966) i n v e s t i g a t e d the n i t r o g e n r e quirements of mature non - pregnant ewes. R e s u l t s showed t h a t when the energy intake was s l i g h t l y i n excess of maintenance, mature ewes (57 kg) could be maintained i n n i t r o g e n  • 73 e q u i l i b r i u m on a d a i l y DCP intake of approximately 1.25 g/kg W  , This  value, although only approximately 30$ of that advocated by Brody (19^5)  4 and the NRC (1957) was i n close agreement with other findings ( E l l i o t and Topps 1964).  However, i t must be noted that the latter workers* results  may not be directly comparable since they found that the level of DCP required for nitrogen equilibrium increased as the ratio of ground roughage to concentrate i n the diet was increased.  Similarly, Vercoe and Hall (1965)  demonstrated that protein requirement was dependent on energy intake and that both were important i n the maintenance of liveweight, liveweight gain, and nitrogen balance i n mature wethers.  However, the results of Graham  (196*1) would suggest that results obtained with mature wethers cannot be applied directly to the breeding ewe which has just undergone the physiological stress of lactation. Robinson and Forbes (1970) carried out a further investigation to study the protein and energy requirements of mature ewes during the post lactation period.  The effect of altering the proportion of,roughage to  concentrate i n the diet on these requirements was also studied.  The results  of the study indicated no effect of roughage-concentrate ratio on the amount of apparently digested nitrogen required to achieve nitrogen equilibrium. The requirement of apparently digested nitrogen obtained i n this study was over 50$ higher than that reported by the same workers i n an earlier study (Robinson and Forbes 1966).  There was a difference i n energy intake between  the two studies and the authors emphasized the importance of defining protein requirements within the context of energy, (b) Protein requirement for pregnancy Various estimates of the protein requirements of pregnant animals have been make from nitrogen balance data. In the case of pigs, a positive nitrogen balance was obtained throughout the pregnancy period on a daily intake of 193 g CP (Lenkeit et a l . 1965) while increasing the f  5  daily intake to 662 g CP increased nitrogen retention after the ? 0 t h day of gestation.  The authors postulated that there i s a phase during the  last month of gestation i n which nitrogen retention increases considerably i f the necessary protein i s provided i n the diet.  Whereas, over the f i r s t  two-thirds of pregnancy, retention i s at a low level and nitrogen given in excess of the low requirement i s excreted i n the urine.  The s i g n i f i -  cance of this increased retention i s not clear since i t i s counterbalanced immediately after parturition by a considerable loss of urinary nitrogen. Considering sheep, several experiments have been carried out on the performance and nitrogen u t i l i z a t i o n of housed ewes during pregnancy. Early work indicated that successful reproduction could be achieved on daily intakes as low as 5 0 g DCP (Klosterman etal. 1 9 5 1 ;  1953)*  However,  these findings have not been generally accepted. Whiting and Slen ( 1 9 5 8 ) studied the influence of energy and protein levels on lamb production i n a large feeding t r i a l .  The workers  found that increasing the energy content of the ration i n early pregnancy increased the liveweight gain of the ewes but did not influence the birthweight of the lambs.  However, increasing energy i n late pregnancy did not  influence liveweight gain of the ewes and tended to depress the birthweight of twin lambs.  By increasing the DCP content of the ration by 5 0 $  liveweight gain of the ewes and birthweight of single lambs was not i n fluenced but significantly increased birthweight of twin lambs and six week weight of singles. The minimum average protein requirement for pregnant ewes based on the results of this t r i a l was 9 0 g/ kg total digestible nutrients (TDN) for maximum lamb production.  The diversity, therefore,  between recommended standards and levels reported to give satisfactory  6  r e s u l t s i n feeding t r i a l s suggested that further research was  necessary  to e s t a b l i s h more p r e c i s e l y the protein requirements of the ewe during pregnancy. An i n v e s t i g a t i o n was therefore undertaken by Robinson and Forbes ( 1 9 6 7 ) to study the minimum requirements f o r protein and i t s u t i l i z a t i o n during the second h a l f of pregnancy,. stage since the morphological  Late pregnancy i s the most c r i t i c a l  growth data of Wallace ( 1 9 4 8 )  showed that  the nutrient requirements of the products of conception were n e g l i g i b l e during e a r l y pregnancy.  The i n t e r a c t i n g e f f e c t of energy on nitrogen  u t i l i z a t i o n as discussed by Chalmers ( 1 9 6 1 ) was also recognized of energy were included i n the study.  and l e v e l s  Four l e v e l s of DCP intake ranging  from approximately 2 7 . 5 to 1 1 0 g DCP per day f o r a 6 8 kg ewe and two l e v e l s of energy, maintenance plus 2 5 $ and maintenance plus 5 0 $ , were adopted. 4.1,  These l e v e l s would represent mean CP intakes per day of 3 * 0 , ,  5 . 5 . and 7 . 2 g/kg W'  73  and ME intakes of 1 1 3 and 1 3 4 kcal/kg  W' . 73  When nitrogen balance studies were c a r r i e d out at 1 0 - 1 2 , 1 4 - 1 6 , and 18-20 weeks of gestation, the stage of pregnancy had no s i g n i f i c a n t e f f e c t on the apparent d i g e s t i b i l i t y of e i t h e r dry matter or p r o t e i n . However, the apparent d i g e s t i b i l i t y of dry matter (DM) and CP decreased with decreasing protein intake,  while a high energy intake caused the  apparent d i g e s t i b i l i t y of DM to increase and that of CP to decrease. Nitrogen r e t e n t i o n increased from mid to l a t e pregnancy i n ewes on the higher energy and protein treatment, however, nitrogen r e t e n t i o n was not affected by the number of fetuses carried„  Therefore,  nitrogen  intake required f o r maximum e f f i c i e n c y just before p a r t u r i t i o n was equivalent to 7 7 g DCP per day f o r a 68 kg ewe.  This i s approximately  3 5 $ lower than generally accepted by Thomson and Aitken ( 1 9 5 9 ) and  7  Phillipson (1959)*  The corresponding  l e v e l of nitrogen r e t a i n e d  was  •73 0.286  g/kg W*  per day ( 6 . 2  g f o r a 68 kg ewe)  and was  considerably  higher than that reported by Klosterraan et a l . ( 1 9 5 3 ) f o r a s i m i l a r n i t r o g e n intake. Several experiments have been c a r r i e d out on the performance and n i t r o g e n u t i l i z a t i o n of housed S c o t t i s h Blackface ewes during pregnancy. McClelland and Forbes (19^8) studied the e f f e c t of DCP 1  and  metabolizable  energy (ME) intake on the performance of ewes weighing 51 kg during the l a s t s i x weeks of g e s t a t i o n .  Three intakes of DCP;  d a i l y were each studied with three intakes of ME; k c a l per day„  6 8 , 91,  and 113  g  1 2 0 0 , 1 6 0 0 , and 2 0 0 0  I t was found t h a t lamb b i r t h weight was  significantly  a f f e c t e d by p r o t e i n intake and the e f f e c t seemed to be more pronounced a t the lowest energy i n t a k e . I n a concurrent nitrogen balance t r i a l (McClelland and Forbes 1 9 6 9 ) i n which the same q u a n t i t i e s of DCP were given and at an energy i n t a k e of 1600 k c a l ME per day, n e i t h e r lamb birthweight nor n i t r o g e n r e t e n t i o n was s i g n i f i c a n t l y a f f e c t e d by p r o t e i n i n t a k e .  There was evidence however, t h a t  the maximum e f f i c i e n c y of n i t r o g e n r e t e n t i o n was achieved on an intake of approximately  69 g DCP per  day.  I n view of these r e s u l t s McClelland and Forbes ( 1 9 7 1 ) decided  that  a f u r t h e r t r i a l should be c a r r i e d out to study p r o t e i n u t i l i z a t i o n on i n takes below and above t h i s l e v e l at which maximum e f f i c i e n c y was i n the e a r l i e r experiment.  achieved  The intakes adopted were 4 5 , 6 8 , and 9 1 g DCP  per day and each were given with the standard ME i n t a k e of 1600 k c a l per day which was found to be adequate i n the previous experiments. average l i v e w e i g h t of the ewes was 5 1 » 5 kg.  R e s u l t s showed no  The significant  d i f f e r e n c e s between the treatments i n l i v e w e i g h t gains of the ewes, lamb  8 b i r t h w e i g h t , or ewe net body weight change (the d i f f e r e n c e between l i v e weight gain over the experimental period and l i v e w e i g h t l o s s a t lambing). When metabolism t r i a l s were conducted during weeks 1 5 - 1 6 and 1 9 - 2 0 of gestation,., no d i f f e r e n c e s i n the apparent d i g e s t i b i l i t y of n u t r i e n t s were observed as the r e s u l t s of advancing stage of pregnancy.  However,, the  apparent d i g e s t i b i l i t y o f CP increased s i g n i f i c a n t l y with the increase i n CP i n t a k e .  The workers showed a s i g n i f i c a n t l i n e a r r e l a t i o n s h i p between  DCP intake and n i t r o g e n r e t e n t i o n .  That i s , d a i l y n i t r o g e n r e t e n t i o n i n -  * .73 , .73 creased by 0.19 g/kg W f o r every 1 g/kg W of apparent digested n i t r o g e n intake per day.  The highest mean intake o f apparently digested  n i t r o g e n i n t h i s study was 0.76 g/kg W  per day, while i n t h e i r e a r l i e r  experiment 1 . 0 5 g gave maximum r e t e n t i o n and 0.78 g gave maximum e f f i c i e n c y (McClelland and Forbes I 9 6 9 ) .  For a 5 0 kg ewe these represent i n t a k e s i n  the range o f 94 t o 114 g DCP per day.  And since the intakes studied i n  t h i s experiment were lower (38 t o 82 g DCP d a i l y ) , t h i s probably accounts f o r the i n a b i l i t y t o e s t a b l i s h l e v e l s of maximum n i t r o g e n r e t e n t i o n and efficiency. (c)  P r o t e i n requirements of ewe lambs There appears to be a l a c k o f information concerning n u t r i e n t  requirements and n u t r i e n t u t i l i z a t i o n i n young growing pregnant ewes. Mating o f females i n t h e i r f i r s t year may accentuate the problems of a r r i v i n g a t these requirements because o f the d i f f i c u l t i e s associated with the p a r t i t i o n of n u t r i e n t s between the dam and the f e t u s .  Provided the  o v e r a l l n u t r i t i o n of the young female i s adequate, the long term reprod u c t i v e performance i s not impared by e a r l y breeding (Coop and Clark 1955; Y a l c i n and Bichard 1964), but there i s a l a c k of information on the e f f e c t on u t i l i z a t i o n of n u t r i e n t s .  9  Of the various nutrients, protein may be of special importance for this type of animal. Robinson et a l . ( 1 9 7 1 ) have studied the u t i l i z a t i o n of protein during pregnancy by ewes bred to lamb at 1 3 months of age.  The overall  mean daily dry matter offered of approximately 1 . 2 kg was within the voluntary intake of a l l the animals.  Assuming a mean requirement of ME  for maintenance for the young growing animal at this stage , of 86 c a l / •73  kg W*  per day, (Forbes and Robinson 1 9 6 9 ) ; the level was approximately  1 . 5 times maternal maintenance. Results showed that as protein content of the diet increased from 1 2 . 3 to l 6 . 5 $ i liveweight gain of the ewes was stable, while lamb birthweights were depressed.  This i s d i f f i c u l t to explain i n view of the  significant increase i n the overall nitrogen retention. However, the decrease i n lamb birthweight resulted i n a decrease i n dam weight loss at parturition and an increase i n maternal liveweight gain.  This suggests  that the partition of protein to the maternal body increased as the CP concentration of the diet was increased.  The authors went on to report  that nitrogen retention increased from the 5 0 t h day of gestation compared to an increase only after the 1 0 0 t h day i n mature ewes, (Graham 1 9 6 4 ; Robinson and Forbes 1 9 6 7 ;  Robinson et a l . 1 9 7 0 ) .  The increase i n nitrogen retention i n early gestation appears to be comparable to that obtained by Elsley et a l . ( I 9 6 6 ) with pregnant g i l t s and may suggest an acceleration i n maternal lean tissue deposition due to the onset of gestation i n growing pregnant animals. The levels of protein intake f a l l within the range studied by Robinson and Forbes ( 1 9 6 ? ) and Robinson et a l . ( 1 9 7 0 ) i n mature ewes. There was approximately a 40$ higher level of nitrogen retention  10 i n the young pregnant females as compared to the mature ewe at 95 days, with no differences at f i v e days prepartum.  Assuming t h i s i s not a breed  d i f f e r e n c e , the high l e v e l of nitrogen r e t e n t i o n i n early gestation i n the young females (occurring as i t does at a time when the f e t a l growth i s small), emphasizes the high requirement of nutrients f o r maternal growth. 2.  Nutrient requirements and u t i l i z a t i o n during l a c t a t i o n  E a r l y experiments i n t h i s area (Slen and Whiting  1952a; 1952b;  1952c) have shown that a l e v e l of 7$ p r o t e i n (59 g DCP d a i l y ) i n the r a t i o n fed to mature ewes during pregnancy and l a c t a t i o n was inadequate f o r normal lamb and wool production. However, l e v e l s of p r o t e i n i n the r a t i o n above 10 percent (1C4 g DCP d a i l y ) resulted i n no greater production than a 10$ l e v e l . (Jordan  Other experiments i n d i c a t e s i m i l a r r e s u l t s  1950; Klosterman e t a l . 1951» Van Horn e t a l . 195l)»  I n most of  these experiments e s s e n t i a l l y i s o c a l o r i c r a t i o n s were used.  (a) E f f e c t of n u t r i t i o n during gestation on l a c t a t i o n performance Whiting and Slen  (1958) studied the e f f e c t of the energy content .  of the r a t i o n on the p r o t e i n requirements o f ewes f o r lamb production* When the energy content of the r a t i o n was increased during l a t e pregnancy and e a r l y l a c t a t i o n (DCP intake between 5k and 109 g DCP and d i g e s t i b l e energy (DE) intake approximately 2.7 and 3«7 Meal), body weight gains o f the ewes were not affected; b i r t h and 6ix week weights o f single lambs and b i r t h weights of twin lambs were not a f f e c t e d .  When the  p r o t e i n content o f the r a t i o n s was increased (from 73 t o 91 to 109 and from 5^ "to 6k to 73 g DCP intake d a i l y i n the two experiments r e s p e c t i v e l y ) , there was no increase i n body weights of the ewes or birthweights of the  11  single lambs, but there was an increase i n the birthweight's of twin lambs. Increasing the protein content of the r a t i o n s increased the s i x week i^eights of single and twin lambs.  The r e s u l t s of these  experiments  suggested that the minimum average protein requirement f o r pregnant and l a c t a t i n g ewes was approximately 1 0 0 g DCP/kg of TDN intake f o r maximum lamb production. The recommended allowances f o r protein f o r ewes of 6 8 kg l i v e weight i n e a r l y l a c t a t i o n given by the NRC ( 1 9 6 8 ) and Morrison ( 1 9 5 9 ) are approximately 1 1 5 and 1 5 0 g DCP per day r e s p e c t i v e l y .  The ARC ( 1 9 6 5 )  based  t h e i r recommendations on f a c t o r i a l estimates and suggested a minimal allowance of 1 6 5 g DCP d a i l y i n e a r l y l a c t a t i o n f o r ewes weighing 5 0 kg and producing approximately 1 kg of milk per day. Hogue ( I 9 6 7 ) concluded from a review of North American recommendations and the r e s u l t s of Gardner and Rogue ( 1 9 6 4 ) ,  ( 1 9 6 6 ) that d a i l y  CP intakes of l 6 l and 1 8 5 g DCP were required f o r single and twin suckling ewes r e s p e c t i v e l y i n e a r l y l a c t a t i o n .  Some of the d i v e r s i t y i n recommen-  dations i s l i k e l y to r e s u l t from d i f f e r e n c e s i n the l e v e l of milk production and the extent to which body reserves are altered during pregnancy and l a c t a t i o n .  The l a t t e r would have a considerable e f f e c t on  the estimates obtained from p r a c t i c a l feeding t r i a l s . Robinson and Forbes ( 1 9 7 0 ) investigated the e f f e c t s of d i e t s during l a c t a t i o n .  The o v e r a l l experiment  included 64 ewes which were  offered 1 6 d i e t s comprising 4 l e v e l s of DCP ( 1 1 0 . 0 , 8 2 . 5 , 5 5 . 0 , and 2 7 . 5 g DCP per 68 kg ewe per day) and two l e v e l s of energy ( 3 2 7 0 and 2 7 2 5 k c a l ME per ewe per day) during gestation. During l a c t a t i o n , h a l f the ewes on each pregnancy treatment were given high energy and low energy ( 5 4 5 0 and 3815 k c a l ME per ewe per day).  Milk q u a l i t y and quantity were a l s o  12  measured. R e s u l t s shewed no s i g n i f i c a n t d i f f e r e n c e s i n d i g e s t i b i l i t y c o e f f i c i e n t s between p r o t e i n intakes during the pregnancy phase (Robinson and Forbes I 9 6 7 ) .  This may suggest a r a p i d adjustment of the rumen micro-  f l o r a when the d i e t s were changed a f t e r p a r t u r i t i o n .  This suggestion i s  i n general agreement with the r e s u l t s o f Lloyd e t a l . ( 1 9 5 & )  who i n d i -  cated that a period of approximately 1 0 days i s s u f f i c i e n t f o r the d i g e s t i b i l i t y c o e f f i c i e n t s of DM and CP t o adjust t o a constant l e v e l a f t e r extreme changes i n d i e t a r y n u t r i e n t i n t a k e s . None of the d i e t a r y treatments during g e s t a t i o n had a s i g n i f i c a n t e f f e c t on milk nitrogen output.  This trend would appear contrary t o the  f i n d i n g s of Robinson and Forbes ( 1 9 6 8 ) who found small responses i n milk production when expressed on a metabolic body weight b a s i s as a r e s u l t of feeding d i f f e r e n t l e v e l s of p r o t e i n and energy during g e s t a t i o n .  They d i d  however, o b t a i n r e s u l t s i n d i c a t i n g a higher n i t r o g e n content of the milk on the higher energy i n t a k e .  This i s i n agreement w i t h f i n d i n g s of Rook  and Line ( 1 9 6 1 ) which i n d i c a t e s that the p r o t e i n content o f bovine milk increases w i t h i n c r e a s i n g DE i n t a k e . Gardner and Hogue ( I 9 6 3 ) studied the o v e r a l l i n t e r r e l a t i o n s h i p of energy l e v e l s f e d t o ewes before and a f t e r lambing.  They summarized t h e i r  r e s u l t s as f o l l o w s : 1.  Varying TDM l e v e l s from 7 5 $ t o 1 2 5 $ of NRC ( 1 9 5 7 ) during the l a s t s i x weeks of g e s t a t i o n d i d not a f f e c t s i n g l e lamb b i r t h w e i g h t s but feeding higher l e v e l s s i g n i f i c a n t l y increased t w i n b i r t h w e i g h t s .  2.  Feeding higher TDN l e v e l s during g e s t a t i o n s i g n i f i c a n t l y increased the average 90-day weight o f twin lambs.  3.  Feeding higher l a c t a t i o n l e v e l s t o ewes increased the weaning  13  weights of both single and twin lambs. 4.  Ewes with single lambs approximately maintained their body weight from six weeks preparturn to weaning when fed 1 0 0 $ of NRC  (1957)  standards whereas ewes with twins required approximately 1 2 5 $ of (1957)  NRC  standards.  Results indicated that the NRC ( 1 9 5 7 ) standard i s satisfactory for ewes pregnant with single lambs.  But levels for ewes pregnant with twin  lambs should be increased, together with an increase i n the total digestible nutrient standard during lactation for ewes with both single and twin lambs. (b)  Protein requirement i n relation to milk production Robinson and Forbes ( 1 9 7 0 ) used two main criteria to assess the  adequacy of dietary CP intake during lactation.  These were, the level of  milk nitrogen output and the level of body nitrogen retention. a value of 1 g  They used  digestible organic matter intake (DOJVLT) equal to 3«32 kcal  ME (Blaxter and Wainman 1 9 6 4 ) and estimated the protein and energy intakes during lactation required for a given level of milk nitrogen production and the associated level of body nitrogen retention.  They showed sig-  nificant correlations between milk nitrogen production and DCP intake during lactation, and between milk nitrogen production and ME intake during lactation.  There were also significant correlations between DCP  intake and nitrogen retention and between ME intake and nitrogen retention. From these correlations the workers reported the DCP  requirement,  as calculated from the overall relationship between DCP intake, ME intake, • 75  and milk nitrogen production to be 7 . 9 g/kg W*  per day.  This i s equiv-  alent to approximately 1 8 5 g DCP per day for a 6 8 kg ewe suckling a mean  14 number of lambs of 1.85 and i s considerably higher than the 114 g advocated by the NRC (1968). With regard to the energy requirement of the same ewe, Robinson and Forbes (1970) suggested that when energy intakes during lactation f a l l 75  below 200 kcal ME/kg W  per day, there i s l i t t l e response i n milk  nitrogen output to alterations i n protein intake. Conversely,, as energy intake increases above this level, the greater i s the response i n milk nitrogen output. Robinson and Forbes (1970) then calculated the energy requirement for zero body weight change i n the ewe and reported the value of 220 kcal 75 ME/kg W*  per day.  When calculated for a 68 kg ewe, this corresponds  to a total daily intake of 5210 kcal ME per day for the production of 2.3 kg of milk.  This value compares favourably with an estimated require-  ment of 54l6 kcal obtained by Had.jipieris et al. (1966) for ewes i n early lactation but i s slightly higher than that advocated by the NRC (1968). The DE intake of lactating ewes has important effects on the volume of milk produced, milk energy yield per day,, and lamb, growth rate (Barnicoat et al.; Thomson and Thomson 1953; Gardner and Hogue 1963t 1964). A ration consisting of 111$ (versus 94$) of NRC (195?) DE recommendations, fed  to ewes suckling single lambs, increased milk production and 90 day  lamb weights by 11 and 17$ respectively without significantly affecting milk composition characters such as fat, protein,, ash, dry matter, or energy value (Gardner and Hogue 1964).  Wilson et a l . (1970) indicated  that the amount and composition of ewe's milk was not influenced by creep feeding the lamb.  However, at different stages of lactation, responses  in the ewe's milk yield and composition to creep feeding of the lamtr, might depend on the energy level supplied to the ewe.  15 In further work, Wilson et a l . (1971), studied the e f f e c t s o f l a c t a t i o n stage, energy l e v e l f o r the ewe,  and creep feeding on the ewe's  milk y i e l d and compostion and rate and e f f i c i e n c y o f lamb growth. experiment 30 Dorset x Merino  I n the  two year o l d ewes suckling t h e i r f i r s t  lambs, were offered a high, moderate, and low energy l e v e l corresponding to 125,  100 or 75$ o f the NRC (1957) recommendations.  Mean i n i t i a l ewe  weight, lamb age and weight were 46.3 kg, f i v e days and 5.2 kg r e s p e c t i v e l y . The estimated DE values f o r the ewe r a t i o n and creep feed were 2881 and  3300 kcal/kg r e s p e c t i v e l y and 12.0  and 14.6  percent p r o t e i n .  The week o f  l a c t a t i o n s i g n i f i c a n t l y affected milk quantity and percent of f a t , t o t a l s o l i d s , s o l i d s - n o t - f a t , protein, and energy.  Amount of milk (estimated  from hand milking the ewes a t three hour i n t e r v a l s ) and milk gross energy produced was greatest during the t h i r d week o f l a c t a t i o n .  Energy intake  of the ewes s i g n i f i c a n t l y affected a l l milk characters except solids-notfat,  ewe weight change, and lamb gain.  of the ewe milk characters.  Creep feeding d i d not a f f e c t any  None o f the two-way i n t e r a c t i o n s i n v o l v i n g  week of l a c t a t i o n , energy l e v e l , o r pre-weaning lamb regime were s i g n i f i c a n t for  the milk or weight change characters i n d i c a t i n g that the main e f f e c t s  were e s s e n t i a l l y a d d i t i v e .  However, the lamb creep feed consumption was  greatest and k c a l s of creep feed DE/g r e c e i v i n g the low energy r a t i o n .  lamb gain was l e a s t f o r the ewes  The l a t t e r values were obtained by  d i v i d i n g the mean d a i l y creep DE consumed by the d i f f e r e n c e s i n lamb d a i l y gain between creep and non-creep-fed groups. and low energy l e v e l s were 17»5t 15*8, gain r e s p e c t i v e l y .  Means f o r the high, moderate,  and 14.6 k c a l creep DE/g  o f lamb  These values i n d i c a t e that the ewe's energy intake  tended t o be i n v e r s e l y r e l a t e d to u t i l i z a t i o n effeciency o f the lamb's creep-feed.  16 (c)  Milk y i e l d and  composition  Milk production of the ewe i s the major f a c t o r i n f l u e n c i n g rate of liveweight gain of the lamb; while the weight of milk rather than i t s n u t r i t i v e value estimated from composition gives the best index of i t s a b i l i t y to promote lamb growth, (Barnicoat et al» 1957)•  The f a c t o r most  capable of i n f l u e n c i n g the quantity of milk produced i s the plane of n u t r i t i o n of the ewe.  Adequate feeding during l a c t a t i o n maintains milk  production i n the important e a r l y stages of the lamb's existence.  Liberal  feeding during pregnancy helps to sustain milk flow, p a r t i c u l a r l y i n the l a t e r stages of l a c t a t i o n , and would presumably exert a dominant influence on the production of colostrum.  Lambs can be weaned at two months of age  without detriment to t h e i r r a t e s of gain (Barnicoat e t a l . 1957)* Milk y i e l d s of ewes vary widely on account of f a c t o r s determined by i n d i v i d u a l i t y .  Breeding from ewes selected f o r l a c t a t i o n performances  would not appear encouraging as a means of improvement, as heredity of characters determining milk production as judged by lamb gains i s low. The influence of the s i r e on the milking q u a l i t i e s of i t s ewe progeny might prove more rewarding. After studying the natural suckling behaviour of lambs Ricordeau et a l . -(-1963) sought t o determine a precise and p r a c t i c a l method of estimating the milk production of ewes during the suckling period by weighing the lambs before and a f t e r suckling.  The workers found that the suckling  i n t e r v a l of lambs on the average was about 1.5 than three hours.  hours and i s never more  There i s l i t t l e difference i n behaviour of suckling  lambs whether they are single or twins.  The suckling frequency v a r i e s  during the day and i n r e l a t i o n to the weight of the lambs, but the most important f a c t o r i s the age of the lambs.  17 They recorded the milk production of 14 ewes over two periods of 48 hours a f t e r double weighings c a r r i e d out every two hours and every three hours. They found the estimation of milk production i n 24 hours i s v a l i d when the weighings r e l a t e to a period of 12 hours, with suckling i n t e r v a l s of two or three hours. Ricordeau and Boccard (196l) studied the r e l a t i o n s h i p between growth of lambs and quantity of milk consumed. 97 ewes (58  From data obtained from  suckling singles, 39 suckling twins), the r e s u l t s showed that  the maximum c o r r e l a t i o n between milk consumed and growth i s reached e a r l i e r f o r twin lambs (period 0-21  days) than f o r single lambs (0-35  days).  The weight of the lambs between 28 and 35 days makes i t possible to give an equally good estimation of the quantity of milk consumed during the corresponding period, as the knowledge of the birthweight and average d a i l y gain of the lamb.  I n a l l cases the standard d e v i a t i o n of the  d i f f e r e n c e s between the quantity a c t u a l l y consumed and the quantity estimated i s about 12$.  During the f i r s t f i v e weeks the r a t e of growth of  single lambs does not depend e s s e n t i a l l y on t h e i r birthweight, as seems to be the case f o r twins.  They found the feed e f f i c i e n c y to be 5«84 and  5«4l kg milk/kg gain f o r single and twin lambs r e s p e c t i v e l y . The median value of f i v e author's estimates of the nitrogen content of ewefe milk i s given by the A g r i c u l t u r a l Research Council (19&5) to be 0.94  g N/100  g of milk.  Using Persian Blackhead ewes ranging i n age from two to ten years, milk composition and the e f f e c t of d i e t on content of milk f a t and milk y i e l d were investigated by Butterworth e t a l . (1968).  Analysis of the  milk of nine ewes f o r f a t , protein, ash, and lactose (by difference) throughout a 12 week l a c t a t i o n gave average values of 5»9# 5*6,  1.0,  and  18 4.8$ respectively.  Ewes fed on a high plane of nutrition gave significantly  more milk containing higher fat than ewes fed on a low plane of nutrition. The fat values were 8.8 and 8.3$ respectively.  Ewes suckling twins gave  significantly more milk.than those suckling singles.  Lambs suckling high  plane ewes gained more weight than those suckling low plane ewes from birth to 12 weeks. Highly significant correlation coefficients were obtained between milk consumed by the lamb and i t s gain i n weight. McCance (1959) and Peart (1968 a) have demonstrated that milk production of ewes i s substantially decreased when nutrient intake i s restricted and Peart (196?. 1968 b) has shown that the total milk production of Blackface ewes i s greatly influenced by the level of production attained i n early lactation.  Peart (1970) obtained results which indicated that the  stage of lactation i s an important factor governing the response to i n creased nutrition and that body condition of ewes at parturition acts as a buffer between nutrient intake and nutrient requirements for lactation. He also suggested that when body reserves of ewes are severely depleted, factors other than nutrient intake may become limiting to milk production. There was a similarity of milk yields and of liveweight change when feed was rationed during lactation weeks one and two, suggesting that the rate of conversion of body reserves to milk, production i s more c r i t i c a l than the total amount, of reserves available during this period. However, when restricted feeding was extended into the third and fourth weeks of lactation, fat ewes suckling twin lambs were able to maintain substantially greater milk production than lean ewes with twins.  These results support  the findings of Forbes (1969) i n contrast to those of Treacher (1971). The efficiency of u t i l i z a t i o n of ewe's milk by the lamb was studied by Jagusch and Mitchell (1971) • The authors found that the mean  19 d i g e s t i b i l i t y of energy of ewe's milk was 98.4$.  They also concluded  that the metabolizable energy requirement f o r zero energy gain was 75 145.2  kcal/kg  per day and the e f f i c i e n c y of u t i l i z a t i o n of ME f o r  maintenance and growth was 76*9$* 3.  Use of rapeseed o i l meal and low q u a l i t y roughage Rapeseed o i l meal Canada i s the l a r g e s t producer and exporter o f rapeseed.  Expan-  sion of the industry has been large i n recent years and i s expected to continueo  Canadian farmers grew about 5»5 m i l l i o n acres i n 1970  y i e l d s being between 400 and 450 kg per acre.  with  The development of new  rapeseed v a r i e t i e s , and p a r t i c u l a r l y ones f r e e of e r u c i c a c i d , has been a success.  I n North America, an improved rapeseed meal could be expected  to supply a s i g n i f i c a n t p o r t i o n of the p r o t e i n supplement required by an expanding l i v e s t o c k industry.  As f a c i l i t i e s are developed f o r crushing  the seed, feed m i l l s w i l l - f i n d rapeseed meal an a t t r a c t i v e a l t e r n a t i v e to soybean meal.  The improved q u a l i t y and use of the meal w i l l , add  to l i v e s t o c k production.  impetus  .  Rapeseed o i l meal became a v a i l a b l e f o r l i v e s t o c k feeding during World War I I (1939-1945) hut i t was known that the meal contained a t o x i c p r i n c i p l e 1-5 v i n y l - thiooxazolidone (Astwood e t a l . 1949) what unpalatable when fed to l i v e s t o c k .  and was some-  The P o l i s h - type rapeseed meal,  Brassica campestrls contains lower l e v e l s of glucosinolates and erucic acid than that o f the Argentine type Brassica nanus.  Early investigations  conducted with turkeys showed severe thyroid enlargements as a r e s u l t of feeding l e v e l s of the meal s u f f i c i e n t to meet the p r o t e i n needs i n p r a c t i c a l grain based r a t i o n s (Blakely and Anderson 1948).  20 B u r k i t t (1951) reported on the d i g e s t i b i l i t y of rapeseed o i l meal f o r sheep and mentioned i t ' s unpalatable nature. B e l l and Weir (1952) found that supplementing marsh hay with rapeseed meal improved the postpartum weights of gestating ewes and improved the q u a l i t y of a l l the lambs and twins i n p a r t i c u l a r as compared to those ewes fed marsh hay alone. -  No thyroid enlargements were noted.  Bezeau, Slen, and Whiting (I960) compared rapeseed meal with l i n seed meal as a source of p r o t e i n for_ pregnant ewes and reported these to produce s i m i l a r r e s u l t s when included i n r a t i o n s a t comparable l e v e l s of up to 20$ of the d i e t .  At l e v e l s above 20$ rapeseed meal was noted to be  unpalatable and t o t a l feed intake decreased.  While the p o t e n t i a l g o i t r o -  genic e f f e c t s of rapeseed meal have been w e l l established, they do not appear to have been reported i n sheep ( B e l l e t a l .  I967).  Impaired reprodtiction when reapessed meal i s fed has been reported f o r r a t s (Manns and Bowland 1963  a; Schuld and Bowland 1968).  A delay i n  sexual.maturity, delayed estrus, and s i g n i f i c a n t l y reduced number of pigs weaned were observed by Manns and Bowland (1963 a) when 8$ rapeseed meal was f e d to g i l t s during growth and gestation. b i r t h were not affected.  L i t t e r size and weight a t  The smaller l i t t e r size and weight a t weaning  have been considered to be due to a l a c t a t i o n a l inadequacy. The adverse e f f e c t s of d i e t a r y rapeseed meal on reproduction could be associated with an iodine d e f i c i e n c y that would show up i n the o f f spring.  D e v i l a t and Skoknic (1971) conducted an experiment to study the  e f f e c t of rapeseed meal as the main source of supplemental p r o t e i n i n the d i e t s f o r pregnant and l a c t a t i n g g i l t s .  Results indicated that g i l t s f e d  12$ rapeseed meal during pregnancy gained s i g n i f i c a n t l y l e s s than those f e d a similar amount of fishmeal p r o t e i n .  21 T o t a l l i t t e r size and weight at b i r t h were s i m i l a r f o r both treatments. However, only 49$ of the p i g l e t s were born a l i v e from the g i l t s fed the 12$ rapeseed meal d i e t ; thyroid glands of l i v e and s t i l l b o r n p i g l e t s were markedly enlarged and symptoms of iodine deficiency were c l e a r l y manifested. Most pigs died w i t h i n 72 hours a f t e r b i r t h and four of the 7 g i l t s l o s t t h e i r whole l i t t e r during t h i s period. meal-fed g i l t s , only 13.4$  Of the t o t a l pigs born t o rapeseed-  survived to three weeks.  I t was concluded  from t h i s study that rapeseed meal of the type fed when used as the main source o f supplemental p r o t e i n f o r g i l t s , may r e s u l t i n a severe iodine d e f i c i e n c y syndrome i n l i t t e r s when non-iodieed s a l t i s used ihDthe d i e t .  Low q u a l i t y roughage I t i s generally recognized that legume forages contain more c a l cium, protein, and carotene than do non-legume forages and they have been shown to be superior i n pregnant ewe r a t i o n s . (Shrewsbury et a l . 1942;; Williams e t a l . 1950)*  However, the l a t t e r i n v e s t i g a t o r s reported l i t t l e  b e n e f i t from the administration of supplementary vitamin A t o ewes r e c e i v i n g any one of several non-legume forages fed with complete mineral supplements. The need f o r good f l e s h i n g i n ewes during l a t e gestation has been emphasized, (Hammond 1932; Thompson and Fraser 1949; and Wallace 1948). Since the differences i n the TDN values of forages, varying widely i n q u a l i t y , are proportionately smaller than the DCP d i f f e r e n c e s ; a t t e n t i o n was focused on the need f o r supplementary p r o t e i n with non-legume roughages. Favourable e f f e c t s due to the a d d i t i o n of p r o t e i n to low-protein hays were observed ( B e l l et a l . 1933; Burroughs et a l . 1950).  22 II.  1.  SUCKLING LAMBS  Nutrient requirements from b i r t h to eight weeks of age The protein requirements of two to s i x week old lambs have not  been firmly established.  The u t i l i z a t i o n of protein by lambs of t h i s age  i s apparently affected by several factors.  Ranhotra and Jordan (1964)  observed no significant increase i n weight gains when s i x to eight week old suckling .lambs were fed either a pelleted ration containing 16.5$ protein or 13»5$ protein.  Conversely, Hinds et a l . (1964) and Mclnnes and  Briggs (1964) reported s i g n i f i c a n t l y greater gains among lambs fed rations containing 1? to 18$ protein than when lower l e v e l s were fed. Three years l a t e r Glimp et a l . (1967) suggested that pelleting creep feed may reduce the protein degradation i n the rumen to a similar degree as heating the soybean meal, thus possibly explaining the lack of agreement between various reports. Poe et a l . (1969) reported that development of the lambs rumen i s affected by the preweaning d i e t with greater r e t i c u l o - rumen growth occurring i n lambs fed high forage than low forage creep rations.  Jordan  and Hanke (1970) conducted an experiment to determine the effect of l e v e l and source of protein supplement (soybean meal or urea) on weight gains of suckling lambs.  The four experiments involving 281 suckling lambs three  to four weeks of age fed ground corn alone or pelleted rations ranging from 9 to 14$ CP equivelent, showed that d a i l y feed consumption tended to be lower i n the urea supplemented rations.  The urea treatment had a s i g -  n i f i c a n t effect on weight gains i n only one r e p l i c a t i o n , and i n t h i s case feed intake was reduced by about one-third. Level of protein, excluding urea fed lambs did not affect weight gains.  23 In the fourth experiment, ninety lambs weaned at four weeks of age and fed r a t i o n s containing 9.8 to 17.5$ of l e s s than 100 d a i l y gain.  g of CP equivalent per lamb s i g n i f i c a n t l y reduced  But, amounts i n excess of 100  n i f i c a n t increase i n gains.  g of p r o t e i n .  average  g r e s u l t e d i n no further s i g -  During the period from four to ten weeks of  age, palatable r a t i o n s containing 13.5 takes of 100  CP showed that d a i l y intakes  to 14$ p r o t e i n w i l l r e s u l t i n i n -  Workers concluded that the main contribution  of a creep r a t i o n i s as a source of supplemental energy and that the ewe's milk provides adequate p r o t e i n .  2.  Rations f o r creep feeding lambs and t h e i r intake  P o s i t i v e lamb growth responses from creep feeding have been observed, (Perry e t a l . 1958; Ross e t a l .  1961; Gardner and Hogue 1963).  The l a t t e r authors also observed a s i g n i f i c a n t i n t e r a c t i o n between l a c t a t i o n DE l e v e l s of the ewes (100  versus 125$  of NRC 1957  recommen-  dations) and type of creep feed (hay versus simple versus complex concentrate mixtures), i n d i c a t i n g that the two e f f e c t s were not a d d i t i v e . However, when the lambs were fed the same simple creep feed i n a subsequent t r i a l , the authors concluded that the amount of creep feed consumed was e s s e n t i a l l y equal regardless of the ewes' r a t i o n energy l e v e l (75  versus  100 versus 125$ of recommendations). Later work by Wilson e t a l . (1970) indicated that the amount and composition of ewe's milk was not influenced by creep feeding the lambs.  24 III.  1.  FEEDER LAMBS  Performance of lambs fed a l l concentrate r a t i o n s Interest i n mechanized feeding operations, r a p i d expansion o f  human population, and the r e s u l t a n t necessity of obtaining maximum nutrient y i e l d per u n i t o f a v a i l a b l e land has r e c e n t l y focused the attention o f research people on the feeding o f a l l concentrate r a t i o n s t o ruminant animals. As e a r l y as 1897» researchers t r i e d unsuccessfully t o rear calves on r a t i o n s devoid of roughages.  Subsequent attempts by McCandlish (1923)  were unsuccessful and postulated that f i b r o u s materials were necessary i n the d i e t of ruminants. Mead and Regan (1931) were the f i r s t workers to conclude that .vroughage was not necessary i n the d i e t f o r calves.  By additions of cod  l i v e r o i l and a l f a l f a ash to a basal r a t i o n o f barley, oats, wheat bran, and l i n s e e d meal; they were able to secure continued normal growth o f calves to 19 months of age.  They considered l a c k o f vitamin A and i n -  adequate minerals to be the l i m i t i n g f a c t o r s i n e a r l y research i n t h i s area. Orskov e t a l . (1971 b) c a r r i e d out an experiment t o investigate the e f f e c t o f feeding barley and a p r o t e i n concentrate with and without hay to f a t t e n i n g lambs.  The r e s u l t s showed that a l e v e l of 5$ hay gave  the greatest d a i l y intake of concentrate, e f f i c i e n t feed conversion.  greatest growth r a t e , and most  However, these parameters were not s i g n i f i c a n t l y  d i f f e r e n t from the lambs fed the a l l concentrate r a t i o n . Recently, Nottle (1972) reported that when sheep were fed 100$ whole wheat or whole oats towards the end of the f a t t e n i n g period, the  25 lambs began to chew the wooden p a r t i t i o n s of t h e i r pens. Hudson et a l .  (1963) studied  r a t i o n fed to feeder lambs.  the response to an a l l concentrate  When 96 lambs were fed f o r 70 days eight  lambs died; f i v e e a r l y l o s s e s showed no evidence of concentrate r a t i o n consumption while three others died from u r i n a r y c a l c u l i l a t e i n the t r i a l . Average d a i l y gain i n the 70 day period was 195 g per day while the average feed consumption was 1.2 kg per day r e s u l t i n g i n a very favourable feed conversion r a t i o of 1.5.6.  F i f t y carcasses showed a general lack of ex-  t e r i o r f i n i s h despite good i n t e r n a l fattening and quality,. Forty representative lambs slaughtered by a meat laboratory received f e d e r a l grades including 7 prime, 23 choice, and 10 good.  No adverse p h y s i o l o g i c a l  e f f e c t s were noted. Keating e t a l . (1964) fed 28 lambs two a l l concentrate r a t i o n s consisting of dry r o l l e d milo or dry r o l l e d b a r l e y .  During the f i r s t  18  days of the 100 day t r i a l , one lamb on the milo and three on the barley ration died.  General, sickness and scouring suggested that lambs on the  barley r a t i o n were under greater s t r e s s .  Lambs on the milo r a t i o n  produced higher d a i l y gains with s i g n i f i c a n t l y improved feed e f f i c i e n c y over the lambs on the barley r a t i o n .  However, the gains were considerably  lower than those reported by Hudson e t a l .  (I963) f o r  lambs on s i m i l a r  rations. A complex study was undertaken by Botkin e t a l .  (1965) to  evaluate  p e l l e t size, concentrate l e v e l s and preparation methods f o r hay or barley when fed i n mixed r a t i o n s f o r f a t t e n i n g lambs.  In the experiment on  p e l l e t siee, 124 lambs were fed two commercially prepared complete p e l l e t s containing 70$ hay and 30$  barley,  to p e l l e t s i z e ; that i s 0.64  the r a t i o n s d i f f e r e d only with respect  cm or 1.90  cm i n diameter.  26 Results showed no appreciable d i f f e r e n c e i n any t r a i t studied between groups o f lambs fed d i f f e r e n t size p e l l e t s .  No d i f f i c u l t i e s were  encountered with lambs i n eating l a r g e p e l l e t s .  This i s i n agreement  with the work of Church e t a l . (1961) who reported no s i g n i f i c a n t d i f f e r e n c e s i n lamb performance due to d i f f e r e n c e s i n p e l l e t s i z e varying from 0.64 cm t o 1«27 cm. In the f i r s t experiment on concentrate l e v e l , two p e l l e t e d r a t i o n s , one containing 45$ barley, 45$ beet pulp, and 10$ dehydrated  a l f a l f a meal,  and the other containing 70$ a l f a l f a hay and 30$ barley were f e d t o 144 lambs f o r 70 days.  Results o f t h i s experiment showed that lambs r e c e i v i n g  the high concentrate r a t i o n gained a t a s i g n i f i c a n t l y slower r a t e than those on the high roughage feed.  I n terms of feed e f f i c i e n c y , dressing  percentage, and carcass grade there was l i t t l e d i f f e r e n c e between the two groups. Lambs receiving, the high concentrate p e l l e t s were d i f f i c u l t t o keep on feed and some deaths occurred.  The lower feed consumption of the  higher concentrate fed lambs was i n proportion to t h e i r gain, and was probably due t o texture o f the p e l l e t s and not to the i n g r e d i e n t s . The p e l l e t s were extremely hard and many lambs showed signs of t h e i r teeth being worn very short by the end of the t e s t .  These lambs also scoured  more r e a d i l y than lambs f e d the high roughage p e l l e t s . Butcher e t a l . (196l) and Meyer and Hull. (1964) found d i f f i c u l t y i n feeding high concentrate r a t i o n s t o lambs. In the second high concentrate experiment by Botkin e t a l . (I965). two r a t i o n s of commercially prepared p e l l e t s , one o f which contained 30$ corn, 30$ barley, 30$ oats, and 10$ dehydrated  a l f a l f a ; while the other  containing 70$ a l f a l f a hay and 30$ b a r l e y were used.  Results o f the l a s t  27  f i f t y - s i x days on t e s t showed rate of gain to be e s s e n t i a l l y the same for both groups.  The lambs fed the high concentrate  feed per day and used feed more e f f i c i e n t l y . i n feed conversion was cost.  p e l l e t s ate l e s s  However, the improvement  i n s u f f i c i e n t to overcome the d i f f e r e n c e i n feed  Contrary to the f i r s t experiment, no d i f f i c u l t y was  encountered  with keeping the lambs on feed with scours or with deaths. In another experiment to study hay and barley preparation, eight r a t i o n s were fed i n c l u d i n g whole, r o l l e d , ground or p e l l e t e d barley mixed with a l f a l f a hay p e l l e t s or with ground a l f a l f a hay.  I n the f i r s t  trial  of t h i s experiment, hay and barley each made up 50$ of a l l r a t i o n s * the second t r i a l a l l m i x t u r e s contained 60$ hay and 40$ barley. r o l l e d barley was  steamed.  In  The  The ground barley was put..through..a 0,5  cm  screen; the p e l l e t e d barley used a 0»6k cm d i e , while the hay was e i t h e r i n the form of 0,64  cm p e l l e t s or chopped using a 5*08 cm  screen.  Results of both t r i a l s showed t h a t treatment s i g n i f i c a n t l y i n fluenced r a t e of gain,, feed e f f i c i e n c y , and feed cost per kg of gain. E f f e c t s of treatment on death l o s s , feed intake, dressing percentage, and carcass grade were not s i g n i f i c a n t .  I n both t r i a l s lambs fed a l f a l f a  hay  p e l l e t s as part of the r a t i o n gained f a s t e r and more e f f i c i e n t l y than those fed  the ground form.  Hopkins ration.  These f i n d i n g s agree with f i n d i n g s of Fontenot and  (1965) comparing  hay p e l l e t s with ground hay as part of a mixed  However, these data do not completely  Meyer et a l .  (1959),  support the postulation of  that increased gains and e f f i c i e n c y of lambs r e s u l t i n g  from feeding p e l l e t s are due to an increased feed intake. they fed a r a t i o n of a l f a l f a hay  Nevertheless,  only.  Results of t r i a l one alone showed gains s l i g h t l y lower (not s i g n i f i c a n t ) f o r lambs fed r a t i o n s with barley p e l l e t s , than those lambs fed  28 r a t i o n s with barley prepared i n any other way. were s i m i l a r regardless of how  the barley was  In t r i a l two, lamb gains prepared.  In both t r i a l s  feed e f f i c i e n c y and feed cost per 100 pounds of gain were s i g n i f i c a n t l y poorest f o r lambs fed r a t i o n s containing barley p e l l e t s . consumption was preparation.  D a i l y feed  not affected to a great degree by method of barley  Whole, r o l l e d , and ground barley were not too d i f f e r e n t  from each other with regard to any measure of lamb performance, although r a t i o n s with r o l l e d barley showed a s l i g h t advantage i n feed e f f i c i e n c y and feed cost per kg of gain. Meyer and H u l l (1964) reported that while r o l l e d and ground barley were e s s e n t i a l l y the same, there was barley i n feed e f f i c i e n c y .  a s l i g h t advantage f o r whole  Jordan (1962) reported no difference i n lamb  performance between whole, steam r o l l e d , or cold r o l l e d barley. In recent work McManus et a l . (1972) studied the  production  responses to mineral buffer supplemented whole wheat grain feeding of lambs.  Thirty-nine crossbred lambs o f f pasture and weighing 27 kg were  group fed on lucerne chaff and whole wheat grain ad l i b i t u m i n yards over a three week adaptation period. 1  whole wheat grain plus 1.5$  A l l animals were subsequently offered  ground limestone ad l i b i t u m f o r 19 weeks.  The a d d i t i o n of mineral buffer supplements of 1:1 Ka^HPO^ and NaHCO^ (buffer I ) or 1:1:1:1 mixture of NagHPO^, NaHGO^, K H C O 3 , and Ca HPO4 (buffer I I ) , as 2$ of the grain offered r e s u l t e d i n s i g n i f i c a n t l y better feed intake and liveweight gains and decreased food conversion r a t i o s as compared to those shown by control sheep fed on wheat grain and Administration of 2.5  limestone.  x 10^ IU i n j e c t a b l e vitamin A to h a l f the lambs over  the f i r s t ten weeks of the experiment seemed to cause neither b e n e f i t nor harm.  29 2.  D i g e s t i b i l i t y of a l l concentrate r a t i o n s In general, the d i g e s t i o n c o e f f i c i e n t s of f e e d s t u f f s used u n t i l  r e c e n t l y were based on an extensive compilation by Schneider (19^7) and Morrison (1956).  The c o e f f i c i e n t s f o r concentrates were determined by  d i f f e r e n c e and u s u a l l y a t low t o t a l concentrate l e v e l s i n the r a t i o n , as compared to present fattening d i e t s f o r ruminants.  Observations by Hale  et a l . (1962) and Saba e t a l . (1964) obtained with a high concentrate or a l l concentrate r a t i o n suggest the d i g e s t i o n c o e f f i c i e n t s f o r p r o t e i n and nitrogen-free-extract (NFE) are considerably lower f o r milo than f o r barley.  The studies reported by Keating e t a l . (1965) provided a d d i t i o n a l  information on the d i g e s t i b i l i t y of a l l concentrate r a t i o n s of milo and barley by ruminants.  Digestion t r i a l s were conducted with c a t t l e t o  determine d i g e s t i b i l i t y o f milo and barley i n a 50$ roughage r a t i o n (19$ orude f i b e r ) and an 85$ concentrate r a t i o n (9$ f i b e r ) .  Digestion  t r i a l s were also conducted with lambs t o determine d i g e s t i b i l i t y o f a l l milo and a l l barley r a t i o n s .  With the 50$ roughage r a t i o n d i g e s t i o n  c o e f f i c i e n t s were similar f o r milo and barley; however, the TDN values were higher f o r milo.  I n the 85$ concentrate r a t i o n s , d i g e s t i b i l i t y of  p r o t e i n and NFE of the barley r a t i o n was s i g n i f i c a n t l y higher than f o r the milo r a t i o n . grains.  The same r e l a t i o n s h i p existed f o r TDN between the two  With lambs on a l l grain r a t i o n s , d i g e s t i b i l i t y of the NFE and  gross energy were noticeably greater f o r milo than f o r barley.  This i s  contrary to the r e s u l t s obtained with c a t t l e and suggests that d i g e s t i b i l i t y values f o r lambs and c a t t l e are not interchangeable f o r high g r a i n r a t i o n s . Nottle (1972) studied the d i g e s t i b i l i t y of whole wheat when fed to sheep at two d i f f e r e n t l e v e l s (675 g and 785 g per day).  30 Data tended to show no d i f f e r e n c e i n d i g e s t i b i l i t y of any parameter due to an increase i n the l e v e l of intake and does not support the  general  assumption that increasing the l e v e l of intake decreases d i g e s t i b i l i t y due to an increased r a t e of passage. feed intake l e v e l s was  However, d i f f e r e n c e s between the  two  small and i t i s possible that one would not expect  a difference i n d i g e s t i b i l i t y . Orskov and Fraser  (1972) i n  a recent report on the d i g e s t i b i l i t y  of whole and processed barley when fed to 6heep, found that dry matter d i g e s t i b i l i t y decreased from 78.2  to 7^.9  liveweight gain increased from 2.56 whole grain before p e l l e t i n g .  and the DM required per kg  to 2.80  This work was  kg as a r e s u l t of r o l l i n g the extended i n a t r i a l i n which  12 lambs were given e i t h e r whole barley or whole barley p e l l e t e d using a 7.8  mm d i e .  The d i g e s t i b i l i t y of the DM and organic matter was  for  the whole unprocessed barley d i e t .  higher  This may have been due i n part  to an increase i n the f i b e r d i g e s t i b i l i t y of the unprocessed r a t i o n and to a presumed s u r v i v a l of c e l l u l o l y t i c b a c t e r i a at the higher rumen pH. 3.  Level of p r o t e i n i n a l l concentrate r a t i o n s  Interest i n p r o t e i n and energy l e v e l s i n f a t t e n i n g lamb r a t i o n s increased a f t e r i n t e r a c t i o n s between these two n u t r i e n t s were shown. Bosshardt e t _ a l ,  (19^6) compared  c a l o r i c intake with p r o t e i n u t i l i z a t i o n  i n growing albino r a t s ; at a given l e v e l of p r o t e i n intake, changes i n c a l o r i c intake often r e s u l t e d in.changes i n the apparent u t i l i z a t i o n of protein.  Donaldson et a l .  (1955) showed  that the energy to p r o t e i n r a t i o  i n the d i e t of chickens influenced the c a l o r i c intake, feed efficiency,, and growth rate, while H i l l et a l .  (1956) concluded  that energy intake of  growing chicks i s governed mainly by d i e t a r y energy concentration and to  31 a l e s s e r extent by p r o t e i n l e v e l .  Lofgreen et a l . (1951) working with  young d a i r y calves, found that the e f f i c i e n c y of u t i l i z a t i o n of p r o t e i n i n high p r o t e i n r a t i o n s , as measured by nitrogen balance, i s markedly influenced by energy intake.  Meyer (1958) when working with r a t s , reported  that a low p r o t e i n intake i n r e l a t i o n to energy influences food intake i n d i r e c t l y through the apparent adverse r a t i o of the two n u t r i e n t s .  He  also went on to state that as the energy portion of the d i e t i s decreased food intake increases because the animal no longer needs t o dispose of the excess energy as body f a t or heat. Jones et a l . (i960) found d i f f e r e n c e s i n both average d a i l y gain and carcass grade as w e l l as feed e f f i c i e n c y between protein l e v e l s fed to 35 kg lambs.  The average DCP on a dry matter basis of the high l e v e l  was 11.2$ versus 8 4$ f o r the low l e v e l . 0  The high l e v e l produced an  average d a i l y gain of 0.1? kg while the low p r o t e i n l e v e l produced an average d a i l y gain of 0.14 kg. tended to grade higher. level. 90$  The lambs on the higher l e v e l of p r o t e i n  Consumption was increased at the higher p r o t e i n  Differences i n liveweight gain or grade between the energy l e v e l s ,  and 120$ of the minimal recommendations of Morrison (1957). were not  statistically significant.  The i n t e r a c t i o n s between protein and energy on  the average d a i l y gain (ADG), carcass grade, and feed e f f i c i e n c y were significant.  The high energy-high p r o t e i n (HR.HP) groups gained f a s t e r  and graded higher than any other groups but the low energy-high p r o t e i n (LE-HP) groups were the most e f f i c i e n t .  The HE-LP groups gained more  slowly, were the l e a s t e f f i c i e n t , and had a lower grade than the other treatment groups.  The estimated net energy (NE) intake f i g u r e s expressed  as percentages of expected or desired consumption show that a l l . groups with the exception of the HE-LP group consumed 90$ or more of the  32 expected amounts. The HE-LP group consumed only 78.6$ of the expected amount of net energy, while the LE-HP group gave the highest percentages of expected consumption.  I t would appear that as the energy level i s i n -  creased, i t i s also necessary to increase the protein level to maintain feed consumption and growth rate of the animals. More specifically, protein requirements of livestock are thought to be a function of many variables and not a specific figure for a l l conditions. Yet, requirements as l i s t e d i n the various NRC publications are specific quantities expressed either as a percentage of the ration or as an amount per animal per day.  This may be a simple way of expressing protein require-  ments but i s probably an oversimplification of the facts. A major need exi s t s i n nutrition research to further qualify the nutrient requirements i n terms of a l l the variables which may cause these requirements to vary. Once the quantitative importance of each of these variables i s determined, the a b i l i t y to formulate rations with predictable results w i l l be enhanced. Three of these variables are known to affect the amount of protein required i n a ration. They are body weight, rate of body weight gain, and d i g e s t i b i l i t y of protein i n the ration. Preston (1966) attempted to integrate these 3 variables into a simple protein requirement for growing-finishing cattle and lambs. He reported the daily digestible protein requirequirements could be expressed by the following equationst cattle lambs  DP = 2.79 W kg (1 + 1.905 DP = 2.79 W kg °»75 (1 + 6.02 0 , 7 5  G) G)  where DP i s i n grams; W kg *"^ i s the animal*s metabolic body weight and G 0  i s the dally gain i n kg.  He suggests further that the above equations need  to be modified such that body weight and weight gain can be replaced by carcass weight and gain of a specific composition such as percentage lean or f a t .  33 Glimp e t a l . (1967) conducted an experiment t o study the e f f e c t s of reducing soybean protein s o l u b i l i t y by dry heat on the p r o t e i n u t i l i z a t i o n a t two l e v e l s , (12.1 and 17.2$) of CP on rate and e f f i c i e n c y of gain and nutrient u t i l i z a t i o n i n lambs 16-20 kg bodyweight and 42-56 days of age.  He showed that heat treatment of soybean meal a t 149 degrees  centigrade f o r four hours had a s i g n i f i c a n t e f f e c t on i t s u t i l i z a t i o n by growing lambs.  Weight gains and feed e f f i c i e n c y of lambs f e d the lower  l e v e l of p r o t e i n containing heat treated soybean meal, were comparable t o gains by lambs fed 17j2$ r a t i o n s containing commercially processed solvent extracted soybean meal.  Heat treated soybean meal when fed i n r a t i o n s a t  a l e v e l t o provide 17«2$ CP d i d not improve lamb performance.  The author  went on t o show that the d i g e s t i b i l i t y o f d r y matter, gross energy, and c e l l u l o s e , and the percentage of d i g e s t i b l e nitrogen retained were s i m i l a r f o r both l e v e l s o f p r o t e i n .  However, increasing the protein content of  the r a t i o n increased p r o t e i n d i g e s t i b i l i t y and increased  nitrogen  retention. Black (1971) using e n t i r e l y l i q u i d d i e t s which passed d i r e c t l y t o the abomasum, determined the protein requirements o f lambs weighing 8 t o 30 kg.  L i q u i d d i e t s were used since i t was thought that the true require-  ments of the lamb's body f o r protein depended on the extent of breakdown of protein i n the rumen.  This may be either underestimated o r over-  estimated when s o l i d d i e t s of increasing protein content are f e d . The i n t e r s e c t i o n of the l i n e representing  the l i n e a r increase i n  nitrogen r e t e n t i o n i n response t o increases i n p r o t e i n intake and the h o r i z o n t a l l i n e representing  the maximum nitrogen r e t e n t i o n was taken t o  be the optimum protein requirement as suggested by Hegsted (1964).  He  established the protein requirements f o r 7.8 kg lambs t o be 4.84 g;  34 for 12.6 kg to be 4.31 g; for 20.8 kg to be 3.34 g and for 30.4 kg lambs to be 2.57 g of reference protein per 100 kcal of net energy. The reference protein requirement was established from a summation of the maximum protein retention and the endogenous protein losses, whereas, net energy was calculated from the metabolizable energy intake by the factors estimated by Walker and Jagusch (1969). The reference protein i s defined as a theoretical protein used solely for tissue synthesis, These results may be applied to either weaned or suckling lambs receiving any protein source, Andrews and Orskov (1970) also studied the nutrition of the early weaned lamb.  They reported that males grew 15$ faster than females; the  difference increasing with age and the amount of feed given.  Growth rate  responded linearly to increase i n feeding level and curvilinearly to i n crease i n dietary protein concentration,  A significant interaction  occurred whereby growth increased with higher protein concentrations as feeding level increased.  At the highest feeding level (near ad libitum)  the results suggest that the optimum dietary CP concentration for growth was about 17.5. 15.0, 12.5, and 12.5$ at body weights of 20, 25, 30, and 35 kg respectively. The overall dietary CP concentration for growth between 16 and 40 kg body weight was about 17.0, 15.0, and 11,0$ when the mean DE intake was 3*0, 2,6, and 2.1 Meal/day. These results agree reasonably well with estimates of protein requirements for lambs given  by the ARC (1965). In further experiments concerning the nutrition of the early weaned lamb, the authors reported that there were significant increases i n the rate of both nitrogen and fat retention with increases i n the level of feeding from 70$ of ad libitum to 85$ of ad libitum to ad libitum.  35 There were also l i n e a r increases i n the rate of p r o t e i n deposition and decreases i n f a t deposition with increases i n the concentration of CP from 10 to 20$ i n the dry matter.  This e f f e c t was p a r t i c u l a r l y marked  at the high l e v e l of feeding. They also indicated that male lambs deposited more nitrogen and l e s s f a t than females.  This was evident i n  both rate of depositon and of carcass composition a t 40 kg liveweight.  (a)  E f f e c t of breed, sex and pre-weaning management on p r o t e i n requirements The extent to which the p r o t e i n requirements of lambs are  generally applicable to d i f f e r e n t breeds and environments has been tested (Orskov e t a l . 1972)*  The authors used three d i e t a r y concentrations o f  CP i n an a l l concentrate r a t i o n to determine the v a r i a t i o n , i f any, i n the requirements o f e a r l y weaned and i n t e n s i v e l y fed lambs at s i x d i f f e r e n t centers i n Great B r i t a i n .  They showed that the optimum p r o t e i n concen-  t r a t i o n of the pelleted r o l l e d barley, white f i s h meal r a t i o n s was i n the r e g i o n of 15 to 17$ CP i n the dry matter.  However, the authors also  pointed out that t h i s may vary depending on the breed and sex,of the lamb and on i t ' s environment and management background i t i s placed on feed.  from b i r t h to the time  For example, feed u t i l i z a t i o n d i f f e r e d  significantly  between breeds, Finn Dorset lambs having lower growth rates and poorer feed e f f i c i e n c y than Suffolk crosses. Female lambs had about 19$ lower growth r a t e s than male lambs.  In terms of preliminary management d i f f e r e n c e s ,  the lambs which suffered the longest growth check (defined as the i n t e r v a l between weaning and the time at which liveweight recovered to the weight the lamb was a t weaning) a t weaning (15*3 days) were those which were a r t i f i c i a l l y - r e a r e d on cold milk substitutes ad l i b i t u m .  I t i s apparent  therefore, that the nutrient requirements of a l l classes of sheep i s  36 dependent on many factors which must be considered when making recommendations, 4,  Rumen development of lambs fed a l l concentrate rations It i s well known that when ruminants are fed diets containing  large amounts of easily fermentable carbohydrates (such as concentrated feed) they often die because of an overproduction of l a c t i c acid i n the f i r s t stomach. This disease i s called l a c t i c acidosis (Mackenzie I967). I t has been empirically stated and experimentally shown that animals can be accustomed to an a l l concentrate ration, by a gradual increase i n the amount of carbohydrate rich diet (Ryan 1964), thus achieving an adaptation to the ration i n such animals. Mechanisms for this adaptation were explained by microbial changes occurring i n the rumen (Bryant and Burkey  1953; Hungate 1957; Maki and Foster 1957; and Palmquist and Baldwin I966). Hungate et a l . (1952) suggested as an alternative mechanism of adaptation, that the microbial population has the a b i l i t y to remove or neutralize the l a c t i c acid i n the rumen. In fact, higher activities of lactate - u t i l i z i n g microorganisms were demonstrated i n adapted rather than non-adapted animals.  On the other hand, Mackenzie (1967) suggested  that low levels of soluble carbohydrates maintained by protozoan activities i n adapted animals prevented new multiplication of l a c t i c acid formers upon the concentrated feed addition.  By adding ground concentrated feed  containing 19$ CP to the non-adapted microbial population invitro. Nakamura et a l , (1971) observed l a c t i c acid accumulation whereas adapted populations were stable with respect to the acid production. Their conclusions for the mechanisms of adaptation to high concentrate feeds differs from those of Reid et a l . (1957). They suggested that the mechanism of  37 adaptation could be attributed to the large number of lactate - u t i l i z i n g bacteria i n the ruminal population, by which normal pH was maintained and therefore balanced flora existing without alteration.  In Nakamura's  experiment, however, pH during the i n i t i a l phase of incubation with the a l l - hay population was higher than that with the hay - concentrate population, although i n the former, f l o r a l change occurred later.  High  levels of easily fermentable carbohydrates would promote lactate formers, on the one hand, and on the other, by suppressing u t i l i z a t i o n of lactate. It should be emphasized that once an amount of carbohydrates continued to exist during the period, sufficient to induce multiplication of lactate formers, subsequent lactate accumulation could not be prevented even i n the hay - concentrate population. Therefore, pH probably i s an important factor for the change i n microflora when animals are fed a l l concentrate rations. Warner et a l . (1959) summarized the factors to date governing the development of rumen. The rumen has an inherent growth potential which i s i n part related to body growth and unrelated to diet.  Dry feed i n -  gestion results i n an increase i n capacity, an increase i n total rumen tissue, and a marked development of rumen papillae.  The rumen expands i n  volume i n approximate proportion to the weight of material i t holds on a day to day basis.  Hay consumption probably results i n a greater expansion  than concentrate consumption because of i t s slower rate of passage which results i n a continual "piling up  w  (within limits) of residue. The  muscle layer of the rumen develops i n response to an increase i n the weight of rumen contents which i t must support and knead. Rumen papillae grow i n response to stimulation by the volatile fatty acids derived from the rumen fermentation.  38 The fact that the order of effectiveness of the three principal acids i s butyrate  >• propionate >• acetate indicates that they e l i c i t their effect  by stimulating the blood flow i n the mucosa and / or by being metabolized by the mucosa. The rumen papillae w i l l be damaged unless an active fermentation (dry feed consumption) i s maintained i n the rumen. With these criteria i n mind,, there should be no reason to discriminate against high concentrate feeding of ruminants, Warner et a l . (1959) reported that when a 90$ hay ration was fed to calves the papillae length was 4.1 mm as compared to 7.5 mm for calves receiving a 90$ concentrate ration. Kunkel et a l . (1962) showed that pelleting a diet of sorghum grain, cottonseed hulls, and dry molasses had no effect on papillary length and that papillary length may be independent of body growth. Slyter et a l . (1970) fed a l l concentrate diets to steers and showed the nominal pH values to be 6.0,  5«2, 5.8,  and 6.1 for corn, wheat,  barley, and milo respectively. Krough (196l) showed that when carbohydrates such as starch were fed i n increasing amounts to sheep, originally given a roughage diet, at a certain level of intake the normal rumen population was quickly replaced by streptococci and l a c t o b a c i l l i and f i n a l l y by yeasts and the animal became seriously i l l .  Eadie, Hobson, and Mann (1967), i n a  survey of the rumen flora of animals fed ad libitum on barley rations, found the rumen pH value was often low and suggested that the microbial population was rather unstable.  Mann (1970) presented the results of a  study on the effects on the rumen bacteria of overfeeding on barley of a heifer already adapted to a barley diet. He presented data to show that i t i s possible to feed large amounts of barley provided that the rate of increase i s small so that the interrelationship between the various  39 bacteria i s not disrupted and the aciduric bacteria do not assume a dominant role. increased.  The rumen pH value f e l l as the amount of l a c t i c acid  He found that the absence of protozoa contribute to high  rumen bacterial counts at rumen pH values below 5«5»  He also demonstrated  that total volatile fatty acids (VFA) and the molar proportion of propionic acid both increased with decreasing pH value.  Fonnesbeck et a l .  (1970) showed that when they fed three different rations: containing 7*8, 9»8, and 11.8$ protein there was no significant difference i n the pH value of the rumen ingesta. Recently McManus et a l . (1972) reported that when mineral buffer supplemented whole wheat w^sifed to lambs on i t s own, the buffer supplements significantly raised the rumen pH values above control animals fed whole wheat grain plus 1.5$ ground limestone ad libitum.  The supplements  also decreased the total rumen volatile fatty acid concentration and lowered the proportion of acetic.acid while increasing that of propionic acid.  Caproic acid was detected i n significant quantities i n the rumen of  a l l sheep. IV.  EXPERIMENTAL METHODS AND CHEMICAL ANALYSIS  One method of doing physiological and nutritional studies with cattle or sheep i s to make complete and separate collections of feces and urine for several consecutive days. Metabolism stalls used to achieve this have been described by Briggs and Gallup (19^9); Erwin et a l . (1956); Nelson et a l .  (195*0; and Aschbacker  (1970).  In this regard, metabolism  stalls are improved upon i n terms of their construction to f a c i l i t a t e complete uncontaminated collection and ease of handling.  Lloyd et a l .  (1956) showed that an adaptation period of ten days was necessary before  40 ruminant animals could be placed on a metabolism t r i a l . errors associated with the determination nitrogen balance studies, Martin  I n a review of  o f nitrogen r e t e n t i o n o f sheep by-  (1966) found  that l o s s of ammonia from  feces was negligable and the l o s s from urine depended on the temperature and pH a t which i t was c o l l e c t e d . C o l l e c t i o n at neutral pH r e s u l t e d i n losses of up to  9,7$>  of the urinary nitrogen as ammonia gas i f an acid  trap were not incorporated i n the c o l l e c t i o n apparatus.  The author showed  the average l o s s of nitrogen when c o l l e c t i n g urine at pH values below 2.0 was  1.33$ when  the ambient temperature was between  25 and 28°  C and 0.97$  when i t was between 15 and 18° C. The d i g e s t i b l e energy value of a feedstuff i s favoured over gross energy as a d e s c r i p t i o n of energy content.  However, determination  value by using a bomb calorimeter can be, as experienced  of t h i s  by the author,  time consuming, f r u s t r a t i n g , and somewhat meaningless since the gross energy content of a l l feed values appear to be s i m i l a r f o r a l l feeds. D i g e s t i b l e dry matter, because i t may be simply and accurately determined, i s at l e a s t i n d i c a t i v e o f feeding value.  Moir  (I96l)  pooled h i s own plus  several other workers' data i n v o l v i n g many d i f f e r e n t f e e d s t u f f s , d i g e s t i b i l i t i e s , and l e v e l s of intake fed to both c a t t l e and sheep and obtained the regression:  y =  0.0462 x  -  0.158 ( r = 0 98l***) o  DM intake and x = DM d i g e s t i b i l i t y $.  where y = DE i n k c a l / g  The regression d i d not deviate  from l i n e a r i t y over the range 0.30 to 83$ DM d i g e s t i b i l i t y , and 1.24 to 3.65 kcal/g. Graham  (I969) derived  an equation to predict metabolizable  intake from d i g e s t i b l e organic matter intake.  energy  The equation was derived by  assuming that d i g e s t i b l e organic matter (DOM) had a gross energy value of  4.40 i  0.02 kcal/g  (Armstrong et a l .  1964).  The equation was:  41 M = 3 7 . 5 1 x d-u where M i s ME (kcal/day); I i s organic matter intake (kg/day); d i s digestibility of organic matter ($); and u i s urinary energy for a fasting animal (approximately equal to 7 0 and 5 0 0 kcal/day for sheep and cattle respectively).  This equation w i l l provide an es-  timate of ME from percent DOM for any level of many diets given to sheep or cattle.  However with diets containing more than 6 0 $ grain, estimates  w i l l be about 1 0 $ too low.  42 C MATERIALS AND METHODS I. 1.  GENERAL METHODS  Experimental Design The main objective of the experiments reported herein was to  study the management and nutrient requirements of sheep raised i n total confinement.  The sheep were fed rations consisting of feeds readily  available i n British Columbia. Two pilot experiments were carried out with mature lactating ewes to obtain estimates of their requirements for protein and energy and to test procedures, f a c i t i l l e s , and equipment. These two experiments are reported i n Appendices I and I I . Four main experiments were carried out.  The objective of Exper-  iment I was to study the reproductive performance and protein u t i l i z a t i o n of ewe lambs bred to lamb at approximately 14 to 16 months of age. Rapeseed meal was compared to soybean meal as a source of supplemental protein during the last half of gestation.  Trials were undertaken to de-  termine the d i g e s t i b i l i t y of the rations fed and the nitrogen retention of the ewes at different stages of gestation. The ewes from Experiment I were used to study the protein requirements during the lactation phase.  (Experiment II) Rapeseed meal  was again compared to soybean meal as a source of supplemental protein for the lactating ewe. The object of Experiment III was to study the influence of energy source and physical form of a l l - concentrate rations for early weaned  43 lambs. Wheat was compared to barley i n either the whole rolled or 5  pelleted form.  Digestibility studies were carried out on each ration  at two levels of intake. Experiment IV was designed to determine more precisely the level of protein supplementation necessary when feeding whole barley based rations to feeder lambs. 2.  Feeding; Trials j  A l l the animals used i n this study formed the entire flock housed on the campus of the University of British Columbia.  The flock,  numbering approximately 80 ewes, was primarily of Dorset Horn breeding including some registered polled Dorset Horns.  Over the two years that  this study was carried out,all ewes were bred to registered rams of the same breed.  The management of the flock was considered to be similar to  other flocks i n the area. With regards to both the ewe and lamb feeding t r i a l s , as many animals as possible were randomly assigned to treatments i n any one experiment.  Every effort was made to feed the animals so that they were i n  similar physical condition before the start of each experiment. A l l animals were housed i n one of two "cold type" buildings.  The  larger building was of essentially pole type construction with wood partioned pens inside.  There was access to the perimeter pens from the out—  side which facilitated easy manure removal and from the inside by means of two alleys. pen space.  Between the two alleys i n the center was located further  The pens had an earth floor and were bedded with wood shavings  or sawdust as required.  The watering bowls servicing each pen were of the  overflow drain type, ensuring a constant supply of clean water to a l l  44 animals.  Adequate feed trough space (type dependent on the form of feed)  was provided f o r each pen, so t h a t a l l animals could eat a t one time. The other smaller b u i l d i n g can be seen i n the photograph below.  I t was o f s o l i d w a l l c o n s t r u c t i o n with w a l l vents plus a 48 cm f a n at one end to ensure adequate v e n t i l a t i o n . The i n d i v i d u a l s t e e l constructed pens were s i t u a t e d on e i t h e r side o f a c e n t r a l feed a l l e y . f l o o r area of approximately 2 . 7 square metres per pen.  The pens provided a Running the f u l l  length of the b u i l d i n g , under the pens, were two manure p i t s approximately 7 0 cm deep.  The s l a t t e d f l o o r s were made of 5 cm square f i r l u m b e r and  were n a i l e d 1 cm apart on two s t r i n g e r s .  The floor was made i n 120 cm sections to f a s c i l i t a t e easy manure removal every 8 months. Fresh water was provided i n each pen by means of nipple drinkers, using a low pressure system.  The individual feeders were  attached to the gates i n front of each pen facing the central feed alley. Feeders were designed to minimize any feed being wasted. A large quantity of feed was stored for each experiment to reduce any differences between batches of feed within any one experiment. A 5 mm die was used to pellet rations. The roughage fed to the group-fed-ewes i n the larger unit was long hay i n baled form while that fed i n the smaller unit was chopped using a 5.08 cm screen ("Haybuster", J.J. Manufacturing, Nebraska); each ewe being fed individually. The feed intake of animals fed either i n groups or as individuals was recorded daily. recorded.  Animals were weighed at seven day intervals and  Recorded and calculated data are given i n the respective portions  of the appendices. These data have been i n turn condensed and included i n the results and discussion sections of each experiment. 3.  Digestibility Trials Ram lambs which formed part of the feeding t r i a l s were used to  determine digestibility and nitrogen retention of the feeder lamb rations. Representative ewes at different stages of pregnancy were used to determine d i g e s t i b i l i t y and nitrogen retention of the ewe rations.  In one case,  however, non-pregnant ewes were used to establish "base l i n e " digestibility and nitrogen balance. Both lambs and ewes used for metabolism studies were allowed at least the ten day adaptation period to the ration and adjustment to i t s  46  l e v e l of i n t a k e .  I n t r i a l s w i t h feeder lambs the c o l l e c t i o n period  lasted a t l e a s t seven days while t h a t f o r the ewes was a t l e a s t f i v e days i n d u r a t i o n .  An e f f o r t was made t o feed and c o l l e c t samples from  the animals a t approximately the same time each day. The ram lambs were housed i n metabolism cages as shown i n the  The ewes were housed i n specially designed cages as shown i n the photograph below.  Cages were designed and built by the author and his advisor, Dr. R. M. Tait.  The features of the s t a l l were:  adjustable for both length  and width, both front and rear openings for easy access, and the ability of the unit to be constructed and dismantled easily.  I t also combines  desirable features of previously described cages such as: construction materials which provide long l i f e , ease of cleaning, complete and total separation of feces and urine, convenience of feed and water containers,  48  and mobility of the entire cage. Abnormal stress created by uncomfortable stalls and rough handling can bias experimental results, therefore, i t i s necessary to give careful consideration to f a c i l i t i e s used i n metabolism studies. this study took these factors into consideration.  The s t a l l built for  Ewes weighing from 40  to 75 kg were easily accommodated i n this cage and appeared comfortable. Total and complete separation could be maintained even when using the different sizes of ewes. Three factors being measured and recorded to determine the digestib i l i t y and nitrogen balance values for each lamb and ewe fed were total daily feed intake, total daily fecal output, and total daily urine output. The total feces and urine output were collected daily and measured. A representative sample of feces of approximately 10$ by weight was dried at 85° C for 24 hours to determine the dry matter output per day.  These  samples were then stored u n t i l a l l daily samples from the t r i a l were collected.  These samples (representing the same percentage of total daily  dry matter output) were pooled, thoroughly mixed, and ground through a one mm screen and stored pending analysis.  A representative sample of  urine of approximately 10$ of the total daily output was combined with each successive days collection and stored at 3° C pending analysis. After each day's urine collection, concentrated I^SO^ was added to the narrow necked vessel at the rate of approximately 0.5$ i n order to ensure the optimum pH to prevent ammonia loss.  A few drops of toluene were also  added daily to further ensure ammonia loss was minimized.  49 II.  CHEMICAL ANALYSES  Precautions were taken when analyzing samples of feed, feces, and urine to ensure that no contamination of samples occurred.  Urine samples  were passed through two layers of cheese cloth before analyzing. The determination of d i g e s t i b i l i t y and nitrogen balance was completed through the use of the following equations: Digestible Dry Matter (DDM $) = DM intake - DM output x 100 DM intake Digestible Crude Protein (DCP#) = 100 x (DM intake x $ CP i n feedDM output x $ CP feces) DM intake x f> CP i n feed Nitrogen Retention (g) = Feed N intake - (Feces N output + Urine N output) Absorbed N = Feed N intake - Feces N output Efficiency of N Utilization ($) = Retained N x 100 Absorbed N Proximate values were computed on a dry matter basis.  Chemical  analyses of feeds, feces, and urine samples were performed according to A0AG  (1965) methods. Acid detergent fiber values of feeds were determined  by the method of Van Soest (1963) as modified by Waldern (1971).  III.  STATISTICAL METHODS  The growth data of the feeder lamb experiment entitled, "The Influence of the Energy Source and Physical Form of A l l Concentrate Rations for Early Weaned Lambs", were subjected to an analysis of variance for a 2 x 3 factorial design. analyzed as a 2 x 2 x 3 f a c t o r i a l .  The d i g e s t i b i l i t y data were  Duncan's multiple range test was  used to determine significant differences (Steele and Torrie, I 9 6 0 ) . The ewe and suckling lamb performance data were subjected to analysis of variance with a single criterion of classification. Duncan's multiple range test was used to determine differences among means (Steele and Torrie, i 9 6 0 ) .  50 D. EXPERIMENTAL  EXPERIMENT I  Reproductive performance and protein utilization of ewe lambs bred to lamb at 14 to 16 months and fed rapeseed meal and low quality roughage.  1. Introduction One of the main factors influencing the biological and economic efficiency of meat production from sheep i s the number of viable lambs produced during the lifetime of the ewe. With the advent of more intensive systems of production, i t i s probable that breeding ewes prior to one year of age w i l l become more widely adopted as a means of increasing overall efficiency. Provided the overall nutrition of the young female i s adequate, the long term reproductive performance i s not impaired by early breeding (Coop and Clark 1955; Yalcin and Bichard 1964). The experiment reported here was conducted to assess the reproductive performance and protein u t i l i z a t i o n of ewe lambs bred to lamb at approximately 14 to 16 months of age. Rapeseed meal was compared to soybean meal as a source of supplemental protein during the second half of gestation. 2. Materials and Methods Twenty - seven polled Dorset Horn ewe lambs weighing approximately 45 kg were bred to rams of the same breed and housed i n individual slotted floor pens 10 weeks prior to the onset of lambing.  51 A l l animals were i n d i v i d u a l l y fed 680 g of grass hay plus 340 g of one of three pelleted concentrate supplements. i s given  The composition of the supplements  (Table l ) . TABLE 1.  COMPOSITION OF CONCENTRATE SUPPLEMENTS  Treatment ($) Ingredients  1  2  3  Barley  20  52  74  Soybean meal  —  —  23  Rapeseed meal  66  35  Dry Molasses  10  10  4  3  Minerals and Vitamins*  *  0.5$  1.0$  3  Cobalt - Iodized s a l t ; 1.5 - 2.2$ Limestone vitamins (435,000 IU vitamin A; 87,000 IU vitamin D; and 1,700 IU vitamin E per kg)  The supplements f o r treatments 1 and 2 were based on rapeseed meal (Brassica campestris) and contained 28.7 and matter basis, r e s p e c t i v e l y .  20.7$ p r o t e i n  on a dry  The supplement f o r treatment 3 was based on  soybean meal and had a protein content of 22.4$ which was intended to be comparable to treatment 2.  The grass hay used as the basal feed f o r the  three treatments had a protein content of  5*9$ on  a dry matter b a s i s .  On the basis of analysed values the p r o t e i n l e v e l s i n the t o t a l r a t i o n were  13.50, 10.83, and 11.40  basis r e s p e c t i v e l y .  f o r treatments  1, 2,  A l l rations provided 2.6  and  3  on a dry matter  Meals of DE per ewe per day.  D i g e s t i b i l i t y and nitrogen balance t r i a l s were conducted with a t o t a l of 16 ewes d i s t r i b u t e d over the three treatments during weeks 9 to 14, 16 to 18, and 19 to 20 of gestation. A l l animals were weighed weekly  52 except during the balance t r i a l s when weighings were c a r r i e d out at the beginning and end of the seven day c o l l e c t i o n period. Samples of feed, feces, and urine were c o l l e c t e d , stored, and analyzed as described i n the general methods section of t h i s report.  3.  Results and Discussion Ewe performance as measured by ewe liveweight changes and  lamb birthweights i s summarized TABLE 2.  (Table 2 ) . EWE PERFORMANCE Treatment  1  2  3  9  9  9  Five weeks prepartum  42.7  45.2  42.6  prepartum  45.8  48.9  46.5  3.1  3.7  3.9  39.8  42.8  40.6  3.76  3.74  3.55  (7M.2F)  (6M.3F)  (3M.6F)  Number of Ewes Ewe weights (kg)  Weight gain post parturn weight Lamb birthweights (kg)  N.S.  N.S.  Ewe weight gains over the f i v e week prepartum feeding period were not s i g n i f i c a n t l y protein.  (p>0.05) affected by the l e v e l or the source of  In comparing treatments 1 and 2, the high l e v e l of rapeseed  meal i n the r a t i o n tended to decrease weight gain of the ewes. This may support the f i n d i n g s of Hussar and Bowland Manns and Bowland (1963  (1959) and  a) who reported a depression i n growth rate and  53 efficiency of feed u t i l i z a t i o n when rapeseed meal was included i n the diets of rats and swine. This depression i n growth and feed intake was found to be related to the level of isothlocyanates present i n rapeseed meal,, I t must be noted that depressed feed intake was not a factor i n the present study as feed intake was held constant for the three groups. Despite the tendency for a lower liveweight gain i n the ewes receiving the high rape diet, there was no significant effect (p>0.05) of diet on lamb birthweights.  This does not support the observation of Robinson  et a l . (1971) that lamb birthweights tend to decrease with increased protein intake i n the case of ewe lambs. However, the protein levels compared i n the present experiment were below those used by Robinson  et a l . (1971). Rapeseed meal resulted i n lamb birthweights similar to those from the soybean treatment at comparable levels of protein intake (treatment 2 versus 3)« The ration used for treatment 1 contained 22$ rapeseed meal. Despite this high level, no gross evidence of goitrogenic effects were observed i n either the ewes or the lambs.  This observation supports  the conclusion of Bell et a l . (1967). The digestibility coefficients for the rations and nitrogen balance data at three stages of pregnancy are summarized  (Table 3)•  Dry matter d i g e s t i b i l i t y was not significantly (p>0.05) affected by either the level of protein or the stage of pregnancy, however digestib i l i t y of the ration containing soybean meal was consistently higher than that of rations containing rapeseed meal.  This difference was not sig-  nificant (p>0.05). The results of McClelland and Forbes (1971) and Robinson and Forbes (19&7) also demonstrated no effect of gestation or  54 protein l e v e l on the d i g e s t i b i l i t y of dry matter.  TABLE 3. DIGESTIBILITY AND NITROGEN BALANCE  Treatment  1  2  3  14  63.58  63.15  66.05  16  to 18  64.01  63.67  65.07  19  to  20  63.26  63.87  64.98  9 to  14  67.24  57.67  61.24  to 18  65.42  58.37  61.75  66.19  56.88  62.30  Apparent Dry Matter Digestibility #  9 to  Week of Gestation  Apparent Crude Protein Digestibility $ Week of Gestation  16  19 to 20 Nitrogen Retention g/ewe/day  9 to  Week of Gestation  14  3.33  1.79  2.46  to 18  2.79  3.35  3.77  19 to 20  4.18  2.37  3.01  16  As was to be expected, apparent protein d i g e s t i b i l i t y was s i g nificantly  (p<0.05)  greater at the higher l e v e l of protein.  Soybean  p r o t e i n had a higher d i g e s t i b i l i t y than that of rapeseed meal when compared at a similar l e v e l of intake; determined by d i f f e r e n c e .  85.58 and 75*92$ r e s p e c t i v e l y  as  Protein d i g e s t i o n was not influenced by stage  of gestation i n any treatment  (p"^0.05).  Nitrogen r e t e n t i o n tended to increase from week 9 to 18 of gest a t i o n on a l l three treatments with no apparent e f f e c t of l e v e l of  55 protein intake.  At the lower l e v e l of protein intake, nitrogen r e t e n t i o n  tended to be lower during the l a s t week of gestation compared with the 18th week.  This was  i n contrast to the higher l e v e l of p r o t e i n which  resulted i n a continued increase i n nitrogen r e t e n t i o n .  The r e s u l t s are  not i n complete agreement with those of Robinson et a l . (1971) who demonstrated a l i n e a r increase i n nitrogen r e t e n t i o n both with increasing protein l e v e l and advancing stage of pregnancy. While these workers demonstrated a s i g n i f i c a n t increase i n nitrogen r e t e n t i o n as pregnancy progressed,  our data d i d not agree with t h i s  f i n d i n g f o r a l l three treatments.  In addition, within the present study  there were unequal observations within the subclasses of stage of gestation f o r the three r a t i o n s . treatments was  For these reasons nitrogen r e t e n t i o n f o r the three  compared on the basis of one stage of gestation only  (weeks 17 to 20),  (Table 4 ) . TABLE 4.  NITROGEN RETENTION G/EWE/DAY  Treatment  range  1  2  3  2.06-7.11  -0.03-5.48  1.89-4.90  mean  4.04  2.80  3.71  standard deviation  1.79  2.49  1.23  While there was no s i g n i f i c a n t  (p>0.05) d i f f e r e n c e between t r e a t -  ments, the values appear to show that ewes on the higher l e v e l of protein retained a greater amount of nitrogen (treatment 1 versus 2).  Ewes  r e c e i v i n g the soybean supplemented r a t i o n also tended to r e t a i n more  56 nitrogen than those receiving rapeseed meal at a similar level of protein intake.  This may have been due to the higher digestibility of the soybean  protein, however the individual animal variation must be noted. Protein u t i l i z a t i o n may have been influenced by the level of energy intake which appeared to be slightly below that required to permit net body weight gain i n the ewe lambs during the later stages of gestation. A l l lambs were healthy at birth and a l l ewes appeared to have an adequate milk supply at parturition.  These results suggest that 11$ crude  protein i n the dry matter supplying approximately 68 g DCP may be adequate for the class of ewes studied.  Rapeseed meal would appear to be a suitable  source of protein and may be used safely even at relatively high levels for pregnant sheep.  57 EXPERIMENT I I  Performance of ewe lambs during l a c t a t i o n when fed rapeseed meal and low q u a l i t y roughage.  1.  Introduction I f the long term reproductive performance of the ewe i s not  to be impaired by e a r l y breeding then i t would seem important to study the performance of the ewe lambs (Experiment I ) during t h e i r l a c t a t i o n phase.  Milk y i e l d s of ewes are extremely v a r i a b l e even within a single  f l o c k of sheep. produced 49.4  Treacher  to 62.7  (1971) reported  that mature Dorset Horn ewes  kg per ewe f o r the f i r s t s i x weeks of l a c t a t i o n .  He  also reported that the l e v e l of feeding during pregnancy or l a c t a t i o n had no e f f e c t on milk y i e l d s . Rapeseed meal was compared to soybean meal as a source of p r o t e i n f o r l a c t a t i n g ewes.  supplemental  An e f f o r t was made to obtain an  estimate of the milk produced and i t ' s q u a l i t y . 2.  Materials and Methods Twenty - seven p o l l e d Dorset Horn ewe lambs weighing  approximately 42 kg post partum were housed i n i n d i v i d u a l slotted f l o o r pens during the eight week l a c t a t i o n p e r i o d . fed 1021  g of grass hay and 500  The ewes were i n d i v i d u a l l y  g of one of three p e l l e t e d concentrate  supplements (Table 1). The supplements f o r treatments 1 and 2 were based on rapeseed meal and contained 32.42 and respectively.  20.45$ crude  p r o t e i n on a dry matter b a s i s  The supplement f o r treatment 3 was based on soybean meal  and had a protein content of  19.53$ which  was intended to be comparable  58 to treatment 2, TABLE I . COMPOSITION OF CONCENTRATE SUPPLEMENTS  Treatment Ingredients  1  2  3  Barley  11  50  74  Soybean Meal  —  —  20  Rapeseed Meal  75  35  Dry Molasses  10  10  4  5  Minerals and Vitamins*  6  * 0.5$ Cobalt - iodized s a l t ; 2.2 to 2.5$ limestone; 1.2 to 2.0$ trace mineral mix; 1.0$ vitamins, supplying 435.000 IU vitamin A, 87,000 IU vitamin D, and 1,700 IU vitamin E per kg.  The grass hay used as the basal feed f o r the three treatments had a protein content of  5*9$ on  a dry matter b a s i s .  The p r o t e i n content  of the t o t a l r a t i o n s were 13.80, 10.08, and 9.79 f o r treatments 1,2, and 3 r e s p e c t i v e l y , based on analyzed values (DM b a s i s ) .  A l l r a t i o n s were  designed to provide 4.0 Meal DE per ewe per day. The experiment was designed so that one h a l f of the animals that received the higher l e v e l of rapeseed meal during pregnancy (Experiment I ) received the lower l e v e l of rapeseed meal during l a c t a t i o n (treatment l ) . The other h a l f of the animals on the high l e v e l of rapeseed meal during pregnancy continued to receive the higher l e v e l during l a c t a t i o n ( t r e a t ment 2 ) .  Conversely, h a l f of those animals r e c e i v i n g the low l e v e l of  rapeseed meal during pregnancy received the higher l e v e l during l a c t a t i o n (treatment 3); while the others continued to receive the low l e v e l  59  during lactation (treatment 4 ) .  Those animals receiving soybean meal  during pregnancy continued to get the soybean ration during lactation (treatment 5 ) • A creep feed ration consisting of 5 0 $ soybean meal and 5 0 $ rolled barley was offered to the lambs at approximately one week of age. 3.  Results and Discussions Ewe performance as measured by ewe weight change and lamb  weaning weights i n terms of both pregnancy and lactation treatment of the ewe i s summarized  (Table 2 ) ,  Due to the fact that there were small numbers of animals per treatment, the weight changes of the ewes and the average daily gain of their lambs could not be analyzed s t a t i s t i c a l l y .  However, the mean values  indicated only a small difference i n the weight changes of the ewes on any of the treatments.  The mean ADG values of the lambs also indicated only  small differences between treatments.  The lambs on treatments 1 and 2  appeared to start consuming creep feed later than those on any other treatment.  This may be evidence to show that the level of protein  offered to the ewe during pregnancy has a notable effect on the lactation phase of the ewe.  TABLE 2.  EWE AND LAMB PERFORMANCE AND  CREEP FEED CONSUMPTION  Treatment 1 HR-LR  2 HR-HR  LR-HR  4 LR-LR  LS-LS  5  5  5  4  9  postparum weights  39.3  38.8  42.4  43.4  4L.5  56 day weight  41.1  39.9  42.1  42.4  42.2  weight changes  +1.8  +1.1  -0.3  -1.0  +0.7  3.65  4.07  3.62  3.89  3.61  Number of Ewes  3  5  Ewe weights (kg)  Lamb weights (kg) birthweight 56 day weight  18.64  18.77  19.60  19.51  17.82  weight gain  14.99  14.70  15.98  15.62  14.21  average d a i l y gain  0.268 (2M.3F)  0.263  0.285  (5M)  (2M.3F)  0.279  0.254  (3M.1F) (3M.6F)  Creep Feed Consumption of Lambs s t a r t of creep consumption (days)  30  28  24  23  23  s t a r t of creep consumption (kg)  10.2  10.6  9.0  9.2  8.6  t o t a l feed intake g  9619  7763  8341  8535  average d a i l y intake g  370  431  253  259  12,033 376  61 A summary of ewe and lamb performance and creep feed consumption (Table 3 ) .  i n terras of the l a c t a t i o n treatment of the ewe i s summarized  TABLE 3.  EWE AND LAMB PERFORMANCE AND  CREEP FEED CONSUMPTION  Treatment  1 High Rape  2 Low Rape  3 Low Soybean  Ewe Performance  14$ CP  10$ CP  10$ CP  number of ewes  9  9  9  post partum weight (kg)  41.7  41.4  41.5  56 day weight  41.1  41.8  42.2  weight change  -0.6  +0.4  +0.7 N.S.  1.02  1.08  1.18  3.69  3.77  3.61  56 day weight  18.90  19.07  17.82  weight gain  15.21  15.30  14.21  milk production (kg/day) Lamb Performance birthweight (kg)  average d a i l y gain Creep Feed  Consumption  age at s t a r t i n days (l0g+/day)  272  273  254  9  9  9  26  27  23  N.S.  N.S.  weight at s t a r t (kg)  9.89  9.71  8.57 N.S.  t o t a l feed intake (kg)  9.66  9.05  8.54  average d a i l y intake (g)  310  295  260  (6M.3F)  (5M.4F)  (3M.6F)  N.S.  62 Weight changes of the ewes over the eight week lactation period were not significantly (p>0.05) affected by the level or the source of protein.  When comparing treatments 1 and 2 the ewes on the higher level  of rapeseed meal tended to lose weight slightly.  The ewes receiving the  soybean supplemented ration tended to gain slightly more weight than those on rapeseed meal at a similar level of protein intake. The average daily gain of the lambs was not significantly (p> 0.05) affected by either the level or the source of protein.  However, i t would  appear that the source of protein had a greater affect on the ADG than did the level of protein fed to the ewe.  The very similar ADG of the  lambs on treatments 1 and 2 i s probably reflected by the similar average daily creep feed intake of those lambs and not due to the feeding regime of the ewes. The lambs on treatment 3 tended to gain less and consume less creep feed than those^ewes receiving the rapeseed protein. The lower creep feed intake of the lambs on treatment 3 compared to treatments 1 and 2 may have been due to a slightly greater amount of milk produced by the ewes on the soybean ration.  The lambs on treatment 3 also started  consuming creep feed sooner i n terms of both age and weight, than those whose dams received rapeseed protein.  The ration used for treatment 1  contained 25$ rapeseed meal and despite this high level, no gross evidence of goitrogenic effects were observed i n either the ewes or. the lambs. This observation supports the conclusion of Bell et a l . (196?). These results suggest that 10$ CP i n the dry matter supplying approximately 92 g DCP may. be adequate for the class of ewes studied.  Rapeseed meal  would appear to be a suitable source of protein and may be used safely even at relatively high levels for lactating sheep.  Low quality forages such as those used i n this experiment may be fed to lactating sheep provided they are adequately supplemented with a high protein concentrate mixture.  64 EXPERIMENT III  The influence of the energy source and physical form of a l l concentrate rations for early weaned lambs.  1.  Introduction Grains or concentrate feeds are more valuable as energy  sources per unit of weight than the best quality roughages. When there i s a small differential i n the costs of good quality roughage and grain, the grain w i l l be the cheaper source of energy. High concentrate rations using barley have become popular for feeding cattle.  Studies by Butcher  et a l . (1961) at the Utah Agricultural Experimental Station demonstrated that lambs can also be successfully fattened on a high concentrate diet i f they can be kept on feed.  The workers at Utah found i t necessary to  have feed available at a l l times and that the feed be pelleted i n order to prevent sorting which they thought would lead to reduced intakes and nutrient imbalance.  The workers compared two rations; a 27$ barley,  60$ a l f a l f a ration was compared to a 85$ barley, 5 $ a l f a l f a ration.  A  significant advantage of the high barley diet was an improvement i n feed efficiency.  They also realized a significant increase i n dressing  percentage for the high barley diet.  They found no detrimental effects  of the high concentrate diet on any of the carcass characteristics studied.  They did find however, that lambs on the high concentrate diet  had a skeleton which was less developed.  However, this was considered a  possible advantage since i t would increase the edible portion of the lamb carcass. Carbohydrates that are fed to ruminants are largely degraded by rumen microorganisms to acetic propionic and butyric acids.  65 In ruminants a large proportion of the dietary energy i s wasted as heat. This i s due i n part to the animal living on energy derived from these fatty acids.  The relative proportions of the various fatty acids produced  i n the rumen affect their efficiency of use.  In general, the more acetic  acid produced relative to propionic and butyric, the lower the efficiency of u t i l i z a t i o n .  Substitution of concentrate for roughage tends to lower  the production of acetic acid relative to the others.  The Utah workers  examined the rumen fatty acid mixtures produced on the high and low concentrate diets and compared these to the feed efficiencies observed i n the fattening lambs. They found that as the amount of barley i n the diet was increased up to a maximum of 85$,acetic acid production decreased and propionic acid increased.  Interpretation of this trend indicates that the nutrients  obtained from the barley diets are used more efficiently than an equal quantity of nutrients absorbed from the roughage diet.  The feed efficiency  data from the lamb fattening t r i a l supported this; the figures showing that 32$ more feed was required for each pound of gain from the roughage diet. Orskov and Fraser (1972) conducted an investigation to determine whether the r o l l i n g of barley before pelleting i s required for the most efficient utilization of the grain by lambs.  Diets consisting of 91$  barley, 7«5$ white fish meal, and 1.5$ limestone were fed. They found that dry matter digestibility decreased from 78.2 to 74.9 (p<0.0l) and the dry matter required per kg liveweight gain increased from 2.56 to 2.80 kg (p  0.05)  as a result of r o l l i n g .  This work was extended i n a  t r i a l i n which 12 lambs were given either whole unprocessed barley on whole barley pelleted through a 7«8 mm die.  66 The lambs given whole barley had a higher pH (6.2 the rumen and a higher proportion of a c e t i c acid  (53ol  of dry matter (80.2  not s i g n i f i c a n t l y changed.  versus 78.9)  and organic matter (83.5  was higher f o r the whole unprocessed barley d i e t .  43.9)  versus  the rumen l i q u o r than those r e c e i v i n g p e l l e t e d barley. b u t y r i c and higher acids was  versus 5*2)  in in  The proportion of The  digestibility  versus  81.6)  This e f f e c t may have  been due i n part to an increase i n the f i b e r d i g e s t i b i l i t y and to a presumed s u r v i v a l of c e l l u l o l y t i c b a c t e r i a at the higher rumen pH. The main purpose of the experiment reported here was  to compare  wheat and barley as the energy source i n a l l concentrate r a t i o n s f o r e a r l y weaned lambs.  The grains were fed i n three p h y s i c a l forms and  of nutrients was determined at two l e v e l s of intake.  digestibility  A short discussion  r e l a t e d to the influence of grain and i t s form on some rumen parameters i s also included.  2.  Materials and Methods  Forty - e i g h t Dorset Horn lambs weaned at eight weeks of age and averaging 20.6  kg were assigned at random to treatments i n a 2 x 3  f a c t o r i a l l y designed experiment. r o l l e d and p e l l e t e d forms. 32$  The grains were supplemented with a commercial  p e l l e t e d protein supplement The  Wheat and barley were fed i n the whole  (Table  1)«  supplement was used at a l e v e l of 25$  of the r a t i o n s u n t i l the  lambs reached approximately 30 kg liveweight at which time i t was reduced to 15$  of the r a t i o n and maintained at t h i s l e v e l u n t i l the lambs were  marketed at a weight of 45 kg.  These l e v e l s of supplementation resulted  i n the barley r a t i o n s having an i n i t i a l CP l e v e l of 17.1$ value of  15.1$  and a f i n a l  67 TABLE 1.  COMPOSITION OF SUPPLEMENT  Ingredient  kg  Wheat shorts  4?9  Cottonseed meal  181  Dry d i s t i l l e r s solubles  91  Urea  32  Salt  36  Dicalclumphosphate  23  Limestone  32  Molasses  32  Premix*  23  *Vitamin A 325 Vitamin D 80 Copper sulphate Cobalt sulphate Manganese sulphate Zinc sulphate Prodine 2  70 60 20 20 300 400 36  g g g g g g g  plus wheat shorts to make 2.3 kg premix  The i n i t i a l and f i n a l CP values f o r the wheat r a t i o n s were 18.4 and respectively.  I t i s i n t e r e s t i n g to note that the whole barley used  throughout the t r i a l s had an average bushel weight of compared t o  16.6$  26.93 kg  23.92 kg/bu  f o r wheat.  While the lambs were suckling, they had access to creep feed based on barley.  At eight weeks of age they were weaned d i r e c t l y onto  the experimental rations which were fed twice d a i l y to appetite.  68 After weaning, no roughage supplements were offered.  Each group of  lambs consisted of four entire males and four females. In conjunction with the growth experiment, a series of digestib i l i t y t r i a l s were conducted to measure the apparent d i g e s t i b i l i t y of dry and organic matter, gross energy, and protein.  These values were  determined for wheat and barley i n the three physical forms and at feed intakes of 600 g and 1,000  g.  Three male lambs weighing approximately  45 kg were used for each determination and the levels of intake represented approximately maintenance and appetite.  The protein-mineral-  vitamin supplement was fed at a level of 15$ of the rations during the digestion t r i a l s .  The total collection technique was employed using a  10 day preliminary period and a 10 day collection for each treatment. Dressing percentage was calculated on representative lambs from the pelleted and whole, barley and wheat groups.  These values were  determined from the warm carcass weight and the liveweight just before being loaded on the truck for shipment.  The lambs had been without feed  for 16 hours prior to shipment. A representative sample of rumen contents was taken at the time of slaughter and within two hours was passed through two layers of cheesecloth.  The resulting f l u i d was centrifuged at 7»000 rpm for 20 minutes.  The pH was read on the resulting supernatant. Also at the time of slaughter approximately 225 square cm of rumen wall were sampled from each animal and stored i n formalin.  Photographs were taken of the rumen  wall samples as well as the rumen contents. Histological sections of the rumen wall samples were prepared.  69 3. Results and Discussions (a) Lamb Performance The average daily gain (ADG), feed conversion ratio (FCR)  f  and feed intake and how they were affected by the type of grain and method of processing are summarized (Table 2 )  TABLE 2.  0  THE MAIN TREATMENT EFFECTS OF GRAIN AND PROCESS ON  AVERAGE DAILY GAIN, FEED CONVERSION, AND FEED INTAKE  Grain Barley Number of lambs  ADG (g)  Process Wheat  Feed intake „ (gDM/kg°'75)  Rolled  Pelleted  24  24  16  16  16  254  242  281a  250ab  213b  4.09  FCR  Whole  79  4.25 78  4.04 88  4.31 81  4.16 68  ab within comparison groupings; means followed by different letters are significantly (p<0.05) different There was no significant (p>0.05) difference between the ADG of the wheat and barley fed groups.  There was, however, a significant  (p-«il0.05) effect of processing with whole grains resulting i n a faster rate of gain than pelleted grains. Rolled grains resulted i n an intermediate rate of gain which was not significantly (p>0.05) different from' either the whole or pelleted forms. There was no significant (p>0.05) interaction between the type of grain and method of processing with regard to ADG.  70 Feed conversion ratios (FCR) were group averages and could not be analyzed s t a t i s t i c a l l y .  However, the mean values indicated only a  small difference i n the FCR of wheat compared to barley with a tendency for barley to be slightly superior.  Similarily, the differences i n FCR  values for the three physical forms were small but there was a tendency for the whole grains to be utilized more efficiently. Feed intake, expressed per unit of metabolic weight (g DM/kgc"»75) and representing the mean feed intake over the growth period was similar for wheat and barley.  The method of processing appeared to influence  this parameter, with feed intake being greatest for whole grains and least with the pelleted form. As with FCR values, feed intakes were group averages and were not subjected to s t a t i s t i c a l analysis. The individual treatment results i n terms of lamb performance are given  (Table 3).  The effect of processing was similar for both wheat and barley, with ADG being significantly (p<0.05) greater for the whole grains than for the pelleted grains.  There was no significant (p>0.05)  difference between whole and rolled or rolled and pelleted forms for either grain. There was a similar trend with both grains for growth rate to be greatest for the whole grain and least for the pelleted form with rolled grains being intermediate.  The FCR values did not show the  same trend as growth rate, however, feed conversion efficiency tended to be superior for the whole barley group. Feed intake followed a similar trend to growth rate with this parameter being greatest for the whole grains and lowest for the pelleted form. both wheat and barley.  This trend was similar for  71  TABLE 3.  LAMB PERFORMANCE AS INFLUENCED BY  WHEAT AND BARLEY IN THREE PHYSICAL FORMS  BarleyWhole Number o f lambs  Rolled  Wheat Pelleted  Whole  8  8  8  8  Rolled  Pelleted  8  8  ADG (g)  292a  251abc  219c  269ab  249abc  208c  FCR  3.85  4.43  2.98  4.22  4.20  4.34  88  84  86  78  70  Feed intake (g DM/kg °»75)  abc means followed by d i f f e r e n t  (p<0.05) d i f f e r e n t  (b)  87  l e t t e r s are s i g n i f i c a n t l y  D i g e s t i b i l i t y of Grains D i g e s t i b i l i t y of gross energy and protein f o r the main  treatment e f f e c t s of process, grain, and l e v e l of feed intake are summarized  (Table 4 ) .  The d i g e s t i b i l i t y of gross energy (GE) was not s i g n i f i c a n t l y (p>0.05) affected by the method of processing.  As was to be expected.,, the  d i g e s t i b i l i t y of energy of wheat was s i g n i f i c a n t l y that of barley.  As the l e v e l of feed intake was increased, there was a  small but s i g n i f i c a n t A significant  (p<0.05) greater than  (p<.0.05) depression i n the d i g e s t i b i l i t y of energy.  (p<!0.05) i n t e r a c t i o n  between grain and process was observed  with regard to the d i g e s t i b i l i t y of energy.  This may be explained by the  d i g e s t i b i l i t y of r o l l e d wheat being s l i g h t l y higher than the other forms of wheat, and the r o l l e d barley having a s l i g h t l y lower value than the  72 TABLE 4. NUTRIENT DIGESTIBILITY COEFFICIENTS FOR THE MAIN TREATMENT EFFECTS Digestibility Coefficients Number of Animals  Gross Energy  Crude Protein  Grain Barley  18  82.1  80.5  Wheat  18  85.7*  84.8*  Whole  12  84.1  82.2 ab  Rolled  12  83.8  84.0 a  Pelleted  12  83.7  81.8 b  600 g  18  84.4  83.9  1000 g  18  83.3*  81.3  Process  Level of Intake  * differences between means are significant (p<C0.05) F test ab means followed by different letters are significantly (p<£0.05) different  other forms of barley.  This result may have been influenced by the fact  that some d i f f i c u l t y was experienced i n keeping lambs on feed at the higher level of feed intake with the rolled wheat ration during the digestion t r i a l s . The digestibility of protein was significantly (p>0.05) i n fluenced by the method of processing.  Protein digestibility decreased  when the grain was pelleted compared to rolled grains, while the value  73 for whole grains was intermediate and not significantly (p>0.05) different from the pelleted or rolled formso  Digestibility of protein  was significantly (p<0.05) lower for barley than for wheat. As was the case with energy, increasing the level of feed intake also resulted i n a significant (p<0.05) depression i n the d i g e s t i b i l i t y of protein. The level x grain, level x process, and second order interactions were not significant (p>0.05). There was a significant (p<0.05) grain x prooess interaction which could be explained by the d i g e s t i b i l i t y of protein for wheat being improved by r o l l i n g , compared to the whole grain. There was no such effect i n the case of barley. As mentioned earlier, the d i f f i c u l t y experienced with the rolled wheat i n the digestion study may have influenced this result. The results of this experiment indicate that rapid liveweight gains and efficient feed conversion can be achieved by early weaned lambs fed a l l concentrate rations.  The ADG of the barley fed group was 254 g  and of the wheat fed group 242 g, while the FCR values were 4.09 and 4.25 for barley and wheat respectively.  These results suggest that either  barley or wheat are suitable energy sources i n a l l concentrate rations for lambs and no digestive disturbances were encountered i n any animals on either grain during the growth study.  These findings confirm those of  Orskov et a l . (1971) who have reported rapid and efficient gains by early weaned lambs fed a l l concentrate diets.  Despite the higher DE concentration  of wheat compared to barley (3.64 versus 3.28 Meals DE/kg DM), the lambs fed barley had a slightly superior growth rate at a similar level of feed intake.  This suggests that the DE of barley was utilized with greater  efficiency than that of wheat.  With regard to method of processing, the best growth rate and feed conversion efficiency was achieved with whole grains, and of the treatments tested, the whole barley group had the best performance.  This  result substantiates the observations of Hanke and Jordan (1963), Meyer  and Hull (1964), Botkin et a l . (1965), and Christensen (1967). The results do not agree with those of Lodge (1966), which indicated that r o l l i n g of barley improved the rate of gain and feed efficiency.  In the  experiment of Hanke and Jordan (1963), i t was observed that pelleting barley depressed feed intake and had an adverse effect on ADG and FCR. This finding i s substantiated by the results of the present experiment. The superior growth rate of the whole grain fed lambs could i n part be explained by a greater feed intake by these animals.  The  differences i n feed intake were particularly noticable i n the early stages of the experiment when whole grains appeared to be most acceptable and pellets least acceptable to the young lambs. I t may be suggested that hard pellets could be responsible for the lower feed intake, however, i t i s the opinion of the author  that the pellets used i n this experiment  were not unduly hard. The d i g e s t i b i l i t y of energy was not significantly (p>0.05) affected by the method of processing, indicating that lambs are capable of digesting whole grains as efficiently as the processed forms.  This  i s i n agreement with the results of MacRae and Armstrong (1969) who also reported no difference between the digestibility of whole and rolled barley.  Orskov and Fraser (1972) have demonstrated whole barley to have  a higher digestibility than pelleted barley for lambs. In the present experiment the whole grains tended to have a higher d i g e s t i b i l i t y of energy than the pelleted form, however the difference was not  75 significant (p> 0.05). In order to ascertain i f the d i g e s t i b i l i t y of whole grains was influenced to a greater extent by the lower level of feed intake compared to the rolled or pelleted forms, the d i g e s t i b i l i t y of nutrients was determined at two levels of feed intake.  The s t a t i s t i c a l analysis of  the main treatment effects indicated that there was no significant (p> 0.05) interaction between the method of processing and the level of intake.  However, i t i s interesting  to compare the d i g e s t i b i l i t y of  energy and protein for the three methods of processing at two levels of intake (Table 5).  TABLE 5.  THE INFLUENCE OF LEVEL OF FEED INTAKE AND  METHOD OF PROCESSING ON NUTRIENT DIGESTIBILITY Level of Feed intake  600 g  Depression i n Digestibility g  1000 g  Digestibility of GE$ whole  85.2  83.0  2.6  rolled  83.6  84.0  _*  pelleted  84.4  83.0  1.7  whole  83.9  80.5  4.0  rolled  85.1  82.8  2.7  pelleted  82.4  80,1  2.8  Digestibility of CP#  * This result may have been influenced by some d i f f i c u l t y experienced i n maintaining lambs on feed at high level of intake with rolled wheat during the digestion t r i a l s .  76 The results indicated that the d i g e s t i b i l i t y of the nutrients was depressed at the higher level of intake with the exception of the d i g e s t i b i l i t y of energy for the rolled grains.  The problem associated  with rolled wheat has been mentioned previously and may have influenced this result.  The results (Table 4),  also suggest that there was a ten-  dency for the d i g e s t i b i l i t y of nutrients of whole grains to be depressed to a slightly greater extent than those of the processed forms as a result of increasing the feed intake from maintenance to appetite.  This was  merely a tendency and was not s t a t i s t i c a l l y significant, therefore i t would appear that the lambs were capable of digesting the whole grains with similar efficiency to the processed forms whether at the maintenance or appetite levels of feeding. The effect of the type of grain and the method of processing on dressing percentage and certain rumen characteristics were assessed (Table 6),  TABLE 6.  THE EFFECT OF GRAIN AND PROCESS ON  DRESSING PERCENTAGE AND CERTAIN RUMEN CHARACTERISTICS  Dressing Percentage  Grain Barley  Wheat  Process Whole Pelleted  51.95  53.49  52.02  no noticeable odor  pungent butyric acid odor  Rumen Characteristics Contents pH ' papillae  5.55 no noticeable differences"  5.56  >  dry,some evidence of whole grains  5.14 long, "leaf like"  53.41 wet, "soup-like" consistency,  5.97 short, "club l i k e "  With regard to dressing percentage, the mean values indicated only a small difference between wheat and barley with a tendency for wheat to be slightly superior.  An effect of processing was observed,  with pelleted grains resulting i n a slightly superior dressing percentage than whole grains. The type of grain and the method of processing appeared to have some effect on certain rumen characteristics.  Rumen contents of wheat  fed lambs gave off a very pungent "butyric acid l i k e " odor, while this was not the case with the barley fed lambs. Pelleted grains caused the rumen contents to have a wet (soup-like) consistency.  This was not ob-  served i n the whole grain fed lambs; the contents being comparitively dry. There was no difference between the rumen content pH values of the wheat and barley fed groups. However, the rumen contents of the lambs fed whole grains were considerably more acidic than those fed pelleted grains.  There were no noticeable differences i n the rumen  papillae of barley compared to wheat fed groups. I t i s interesting to note, however, that those lambs fed whole grains had long, "leaf-like" papillae compared to the short "club-like" characteristic of pelleted grain fed lambs.  78 EXPERIMENT IV  The influence of the level of protein supplementation of whole barley - based rations for early weaned lambs.  1.  Introduction There i s considerable variation i n the estimated protein  requirements of young growing lambs. I t i s probable that much of this variation i s a result of differences i n the age and rate of gain of the lambs studied.  Also most values have been obtained using low energy  rations consisting of high proportions of roughage. Andrews and Orskov  (1970) carried out one of the few experiments on protein requirements of early weaned lambs using a l l concentrate rations. They suggested that when these rations were fed ad libitum, the optimum crude protein concentration of the ration should be 17.5, 15*0, 12.5, and 12.5$ at body weights of 20, 25, 30, and 35 kg respectively. Now that the grain and the form of that grain has been established as the ideal ration for feeding lambs, i t would seem necessary to establish more precisely the amount of protein supplementation necessary to give optimum economical gain and feed  conversion.  The experiment reported here was therefore designed to assess the performance of early weaned lambs fed whole barley based rations with different levels of protein supplementation. 2. Materials and Methods Fifty - four polled Dorset Horn lambs, weaned at eight weeks of age and averaging 20 kg were assigned at random to four treatments. The treatments consisted of whole barley plus a 32$ protein pelleted  79 supplement (as described i n Experiment III) i n order to obtain different levels of protein i n the ration during three periods of growth (Table l ) . TABLE 1.  LEVELS OF PROTEIN IN THE RATION  DURING THREE PERIODS OF GROWTH  Period  1  2  3  Treatment  20 to 29 kg  29 to 36 kg  36 to 45 kg  1  18  18  18  2  18  15.5  13  3  16  13.5  11  4  14  14  14  The barley and protein supplement contained 12.5$ and 36.2$ protein on a dry matter basis, respectively. In conjunction with the growth experiment, a series of d i g e s t i b i l i t y studies were conducted to measure the apparent d i g e s t i b i l i t y of dry matter and protein. These values were determined for the 18$ protein ration when fed during the three periods of growth.  Three male lambs were used for each deter-  mination and the levels of intake at 600 g, 900 g, and 1000 g represented appetite.  The t r i a l s were carried out when the average of the three  lambs weights were 25, 35. and 40 kg to represent growth periods 1, 2, and 3 respectively. In a subsequent t r i a l , three male lambs were used to determine the d i g e s t i b i l i t y of 1000 g of whole barley when fed alone.  When the  protein level of any ration was below 13$, additional minerals and vitamins were supplied i n addition to those supplied i n the protein  80 supplement. 3.  Results and Discussion The main effects of level of protein during three periods of  growth on the average daily gain and feed conversion efficiency are presented  (Table 2).  When comparing the ADG and FCR of a l l the lambs on a l l treatments during period 1 (20 - 29 kg) i t would appear that the most efficient gain was obtained when the lambs received 16$ CP i n the ration.  When the  mean ADG of a l l lambs receiving 18$ CP (treatments 1 and 2 combined) i s compared to treatments 3 and 4 the greatest growth rate was achieved by those lambs receiving 16$ CP i n the ration.  I f FCR values are viewed i n  the same manner, the 16$ CP i s again the best ration.  A 14$ CP ration for  fattening lambs during this i n i t i a l stage would apparently be insufficient due to the fact that the lambs on this ration realized the lowest ADG and consumed the greatest amount of feed per unit gain. In period 2 (29 to 36 kg) those lambs fed the 14$ CP ration produced the most economic gain.  I t must be noted however that the lambs  on this ration may have compensated for shortage of protein i n their ration during the i n i t i a l period of growth. During the f i n a l finishing period from 36 kg to market weight, the results suggest that one could continue to feed 14$ CP i n an a l l concentrate ration. (1970).  These levels compare favourably with those of Andrews and Orskov  81 TABLE 2.  THE EFFECT OF THE LEVEL OF PROTEIN DURING THREE  PERIODS OF GROWTH ON THE AVERAGE DAILY GAIN Al© FEED CONVERSION Average Daily Gain (ADG)g. Period 1  2  20 to 29 kg  29 to 36 kg  3  36 to 45 kg  Treatment  1. 18 - 18  - 18  253  >>242  235  244  238  250  2. 18 - 15.5 - 13  231  3. 16 - 13.5 - 11  247  235  219  4.  233  318  238  4.36  5.11  14 -  Ik  - 14  Feed Conversion Ratio  (FCR)  Treatment 1.  18 - 18  2.  18 - 15.5 - 13  3.^3  4.36  5.16  3.  16 - 13.5 - 11  3.36  4.60  5.57  4.  14 - 14  3.82  4.15  4.94  - 18  - 14  3.12' • 3.28  The effect of the level of protein over the entire feeding period on average daily gain and feed efficiency are summarized (Table 3). When comparing the ADG and FCR over the entire feeding period i t would again appear that lambs require 16$ CP i n an a l l concentrate ration during the i n i t i a l growing period.  82 TABLE 3.  THE EFFECT OF THE LEVEL OF PROTEIN OVER THE  ENTIRE FEEDING PERIOD ON THE ADG AND  FCR  Treatment*  Average daily gain Feed conversion ratio (FCR) g  1  2  18-18-18  18-15.5-13  246 4o06  234 4.44  16-13.5-13  14-14-14  237 4.22  262 4.35  When the lambs reach a weight of approximately JO kg, i t would appear that a ration consisting of 14$ CP would be the optimum level to produce the most economical gain.  The slightly superior FCR of those lambs fed  18$ CP during the entire feeding period (treatment l ) would not warrant the extra cost of supplementation.  The ADG and FCR of lambs on treatment  3 were slightly superior to those on treatment 2, which indicates that a ration consisting of 16$ CP can be fed to lambs during the i n i t i a l growing phase and that approximately 14$ CP i n the ration from 30 kg to market weight would be the best feeding regime for lambs. The superior ADG of lambs (treatment 4) receiving 14$ CP i n the ration would tend to indicate that 11$ CP (no protein supplement added to the barley during the f i n a l finishing period, treatment 3) would be inadequate. Digestibility Digestibility coefficients for dry matter and crude protein as well as nitrogen retention values for four treatments fed at three periods of growth are presented (Table 4).  83 TABLE 4. NUTRIENT DIGESTIBILITY COEFFICIENTS  —  FOUR TREATMENTS AT THREE PERIODS OF GROWTH Average weight of lambs (kg) (period of growth)  Apparent digestibility of dry matter  Apparent digestibility of crude protein  Nitrogen retained g/day  Treatment 18$ CP  25 (1)  83.97  82.68  6.04  18$ CP  35 (2)  84.24  83.50  6.74  18$ CP  40 (3)  83.68  83.30  9.14  11$ CP  43 (3)  80.91  71.42  3.77  (100$ whole' barley)  The results of the digestibility studies (Table 4), suggest that the apparent digestibility of dry matter and crude protein does not change with increasing body weight of the lamb.  The increase i n nitrogen  retention as the lambs gained weight i s d i f f i c u l t to explain i n view of the fact that the amount of feed required per unit gain increased as the lambs approached market weight.. The apparent d i g e s t i b i l i t y of dry matter and crude protein of the whole barley when fed alone to lambs (80.91 and 71.42 respectively) compare favourably to literature values.  84 E.  SUMMARY  The r e s u l t s of t h i s study appear to i n d i c a t e that i t i s both economical and b i o l o g i c a l l y f e a s i b l e to r a i s e sheep under t o t a l confinement conditions provided t h e i r n u t r i t i o n a l and management requirements are met.  These requirements can be achieved using feeds and techniques  available to sheep producers i n B r i t i s h Columbia.  The b i o l o g i c a l and  economic e f f i c i e n c y of such a production system i s dominated by the resources required to maintain the breeding  ewe.  Provided the o v e r a l l n u t r i t i o n of the young female i s adequate, the long term reproductive performance  i s not impaired by e a r l y breeding.  Ewe lambs may be bred to lamb at 14 months of age and a t 8 month i n t e r v a l s thereafter and hence a t t a i n maximum lambing performance.  These ewes  can u t i l i s e low q u a l i t y roughage during both the pregnancy and l a c t a t i o n periods providing i t i s adequately supplemented with a concentrate mixture.  Rapeseed meal or soybean meal may be used i n such a supplement to  provide approximately 11$ CP i n the r a t i o n during l a t e pregnancy and e a r l y lactation.  Feed intake during l a t e pregnancy should be such that  ewe  lambs (45 kg) are ensured of r e c e i v i n g approximately 68 g DCP and  2.6  Meal DE per ewe per day.  I n the l a c t a t i o n period these ewes apparently  require about 92 g DCP and 4.0 Meal DE per ewe.  Rapeseed meal when fed  at l e v e l s of 22 and 25$ of the pregnancy and l a c t a t i o n r a t i o n s respect i v e l y , d i d not cause any detrimental e f f e c t s i n either the ewes or the lambs. Suckling lambs do not appear to consume appreciable amounts of creep feed u n t i l they are 3 to 4 weeks of age or approximately 9 to 11 kg. The r a t i o n ingredients and nutrient composition of creep feed do not appear to be as c r i t i c a l as p a l a t a b i l i t y and hence intake with regard  85 to lamb growth r a t e . Dry matter and protein d i g e s t i b i l i t y of the rapeseed meal and soybean meal rations were not affected by the stage of pregnancy of the ewe.  Nitrogen r e t e n t i o n tended to increase with advancing  pregnancy  up u n t i l the 18th week of gestation, however, no consistent increase was noted a f t e r t h i s period. The r e s u l t s of the experiments with mature ewes would suggest that the nutrient requirements of t h i s c l a s s of animal suckling single lambs are quite d i f f e r e n t from the requirements of those with twins.  A level  of 227 g DCP and 6,6 Meal DE d a i l y would appear to be adequate f o r the former while 272 g DCP and 8,4 Meal DE d a i l y may be closer to the requirement f o r ewes with twin lambs.  This becomes even more apparent  when the ewes are bred to lamb every eight months. E a r l y weaned lambs are capable of e f f i c i e n t u t i l i z a t i o n of a l l concentrate d i e t s .  Wheat and barley as the energy source produced  similar r e s u l t s i n terms of growth r a t e and feed conversion e f f i c i e n c y . Whole grains and i n p a r t i c u l a r whole barley, supplemented with a protein concentrate to provide a 16$ CP r a t i o n during the i n i t i a l fattening period (weaning to 30 kg), resulted i n the best animal performance.  A  14$ CP r a t i o n i s suggested to f i n i s h lambs from 3 0 kg to market weight. In terms of d i g e s t i b i l i t y , whole grains were u t i l i z e d with equal e f f i c i e n c y to that of processed forms even when fed to appetite.  Feeding  a l l concentrate d i e t s to lambs d i d not have any detrimental e f f e c t on either dressing percentage or on rumen development.  I t would appear that  processing cereal grains f o r lambs i s unnecessary i n terms of both d i g e s t i b i l i t y and animal  performance.  86 BIBLIOGRAPHY  1. A g r i c u l t u r a l Research Council. farm l i v e s t o c k .  I965. Nutrient requirements of  No. 2. Ruminants.  London, England.  2. Andrews, R.P. and Orskov, E.R. 1970. The n u t r i t i o n of the e a r l y weaned lamb. I . The influence o f protein concentration and feeding l e v e l on rate o f gain i n body weight. J . Agr.  S c i . 75: 11-18.  3.  Armstrong, D.G., Blaxter, K.L. and Waite, R. 1964. The evalua t i o n o f a r t i f i c i a l l y dried grass as a source o f energy f o r sheep. I I I . 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Dietary rapeseed meal f o r swine reproduction. Can. J . Anim. S c i . 48: 57-64.  135.  Shrewbury, C.L., Harper, C , Andrews, F.N. and Z e l l e , M.R. 1942. The l i m i t a t i o n s of oat straw as a roughage f o r maintenance, l a c t a t i o n , and growth i n sheep. J . Anim. S c i . 1:126.  136.  Slen, S.B. and Whiting, F. 1952. Wool production as affected by the l e v e l of protein i n the r a t i o n of the mature ewe. J . Anim.  S c i . 11: 156-165.  137.  Slen, S.B. and Whiting, F. 1952. Lamb production as affected by the l e v e l of protein i n the r a t i o n of the mature ewe. J . Anim.  Sci. 11: 166-173.  138.  Slen, S.B. and Whiting, F. 1952. Further observations on the e f f e c t of l e v e l of protein i n the r a t i o n of the mature ewe on wool and lamb production. S c i e n t i f i c Agr. 32: 375-379.  139.  S l y t e r , L.L., Oltjen, R.R., Kern, D. L. and Blank, F.C. 1970. Influence of type and l e v e l of grain and D.E.S. on the rumen microbial populations of steers fed a l l concentrate d i e t s . J . Anim. S c i . 31: 996-1002.  140.  Steele, R.G.D. and T o r r i e , J.H. i960. P r i n c i p l e s and procedures of s t a t i s t i c s . McGraw-Hill Book Co., New York, N.Y.  141.  Thompson, W. and Fraser, H.H. 1949. Feeding concentrates t o i n lamb ewes. Scottish J . Agr. 22:71.  142.  Thomson, A.M. and Thomson, W.T. 1953. y i e l d of ewe and growth of her lamb.  143.  Thomson, W. and Aitken, F.C. 1959. Bur. Anim. Nutr. 20.  144.  Treacher, T.T. 1971. E f f e c t s of n u t r i t i o n i n pregnancy and i n l a c t a t i o n on milk y i e l d i n ewes. Anim. Prod. 13: 493-501.  145.  Van Horn, J.L. 1951. N u t r i t i o n a l requirements of ewes wintered under range conditions. I . Protein requirements. Montana Agr. Exp. Sta. B u l l . 56.  E f f e c t of d i e t on milk B r i t . J . Nutr. 7:263.  Tech. Commun. Commonwealth  97 146.  Van Soest, P.J. 1963. Use of detergents i n the analysis of fibrous feeds. I I . A rapid method for the determination of fiber and l i g n i n . J . Ass. Offic. Anal. Chem. 46: 829-835.  147.  Vercoe, J.E. and Hall, W.B. 1 9 6 5 . The influence of the chemical composition of the diet on the liveweight change i n sheep. Aust. J . Agr. Res. 1 6 : 6 7 5 .  148.  Waldern, D.E. 1971. A rapid micro digestion procedure for neutral and acid detergent fiber. Can. J . Anim. S c i . 5 1 : 6 7 - 6 9 .  149.  Walker, D.M. and Jagusch, K.T. 1 9 6 9 . Energy metabolism of farm animals. Blaxter, K.L. ed. Oriel Press, Newcastle Upon Tyne. p. 187.  150.  Wallace, L.R. 1 9 4 8 . Growth of lambs before and after birth i n relation to the level of nutrition. J. Agr. S c i . 38:93.  151.  Warner, R.G., Harrison, H.N. and Sander, E.G. 1959. The effect of various dietary factors on the development of the rumen. Cornell Nutr. Conf. for Feed Manuf.  152.  Whiting, F. and Slen, S.B. 1 9 5 8 . The influence of protein and energy content of the ration on lamb and wool production of range ewes. Can. J . Anim. S c i . 3 8 : 208-216.  153.  Williams, S.B., Sylvestre, P.E., Bowstead, J.E., Ewan, A.H., Meyer, P.I. and Peters, H.F. 1 9 5 0 . Supplemental feeding of pregnant ewes. Scientific Agr. 3 0 : 1 - 1 1 .  154.  Wilson, L.L., Rugh, M.C., Ziegler, J.H., Varela - Alvarea, H., Simpson, M.J., Watkins, J.L., Stout, J.M. and Merritt, T.L. 1 9 7 0 . Effect of pre-weaning regime, breed of lambs sire, and lamb sex on milk production of the ewe and growth and carcass t r a i t s of the progeny. J. Anim. S c i . 31:136.  155-  Wilson, L.L., Varela - Alvarez, H., Hess, C.E. and Rugh, M.C. 1 9 7 1 . Influence of energy level, creep feeding, and lactation stage on ewe milk and lamb growth characters. J . Anim. S c i . 33:686.  I56.  Yalcin, B.C. and Bichard, M. 1 9 6 4 . Crossbred sheep production. I. Factors affecting production from the crossbred ewe flock. Anim. Prod. 6 : 73-84.  y  APPENDICES I TO V.  99  The experiments as reported i n Appendices I and I I were c a r r i e d out mainly as p i l o t s t u d i e s t o o b t a i n i n d i c a t i o n s of the l e v e l s of p r o t e i n necessary f o r l a c t a t i n g ewes.  These experiments were also used  to t e s t procedures, f a c i l i t i e s , and equipment which had been designed for p r e c i s e determinations of i n t a k a and d i g e s t i b i l i t y of r a t i o n s . The experiments reported i n t h i s study gave r i s e t o a l a r g e volume of raw data.  For s i m p l i c i t y reasons these data are not included  i n the appendix but are tabulated and recorded i n the Department of Animal Science f i l e s .  100  APPENDIX I  A comparison of the performance of mature ewes s u c k l i n g s i n g l e or twin lambs and f e d two l e v e l s of energy at a constant l e v e l of p r o t e i n .  1»  Introduction The l e v e l s of energy and p r o t e i n fed to the ewe during ges-  t a t i o n and l a c t a t i o n have been shown by many workers to have a s i g n i f i c a n t influence on lamb birthweights and subsequent growth r a t e s .  However,  there i s not complete agreement as to the l e v e l s of p r o t e i n and energy to feed nor when increases i n energy and p r o t e i n fed are most valuable f o r maximum lamb growth. Gardner and Hogue ( 1 9 & 3 ) found t h a t feeding higher energy and p r o t e i n l e v e l s during l a t e g e s t a t i o n and l a c t a t i o n than recommended by NRC ( 1 9 5 7 ) , increased the 9 0 day weights of both s i n g l e and t w i n lambs. The primary o b j e c t i v e of the experiment reported here was to determine the o / e r a l l i n t e r r e l a t i o n s h i p of energy and p r o t e i n l o v e l s f e d to ewes s u c k l i n g s i n g l e and twin lambs and of creep r a t i o n s on the growth of lambs. 2.  M a t e r i a l s and Methods The 2k animals used i n the experiment formed p a r t of a f l o c k  of p o l l e d Dorset Horn mature ewes ranging i n age from 2 t o 5 years.  The  ewes had been bred to rams of the same breed and up u n t i l the beginning of the exporiment had received approximately 1 . 8 kg of grass - legume hay per ewe per day.  Twelve of the ewes weighing approximately 55 kg had  s i n g l e lambs and were d i v i d e d e q u a l l y among treatments according to age and weight while the other 12 had twin lambs and ware a l s o d i v i d e d  101 equally among treatments according to age and weight. A l l the ewes were housed and fed i n the four treatment groups for the eight weeks of lactation.  A l l ewes received 1.8 kg of a l f a l f a - brome hay plus one of  four concentrate supplements (Table l ) .  TABLE 1.  COMPOSITION OF CONCENTRATE SUPPLEMENTS  Treatment Singles Ingredients  1  Twins  2  3  4  Rolled barley  85  94.5  86.5  96  Soybean meal  8  —  8  —  Minerals *  6  4.5  4.5  3  Vitamins **  1  1  1  1  * a l l rations were designed to provide 0.28$ calcium, 0.21$ phosphorus, 0.5$ salt ** a l l rations provided 559 IU vitamin A and 62 IU vitamin D per kg  102 The treatments were comprised of two l e v e l s of DCP  and three  l e v e l s of energy intake (Table 2).  TABLE 2.  TREATMENTS  1 intake per ewe per day a l f a l f a brome hay (kg)  2  3  singles  4 twins  1.8  1.8  1.8  1.8  concentrate supplement g  318  590  771  1225  DCP  227  227  272  272  g (estimated)  DE Meal (estimated)  5.5  6.6  6.6  8.4  d a i l y feed intake per ewe kg ( a i r dry)  2.13  2.40  2.59  3.04  When the lambs reached approximately 14 days of age they were offered a 1:1 mixture of flaked corn and soybean meal u n t i l they reached approximately s i x weeks of age, at which time they were given a  1:1:1  mixture of corn, soybean meal, and r o l l e d b a r l e y . The composition of the feeds used i n both the ewe r a t i o n s and the lamb creep feed i s presented (Table 3). TABLE 3.  Ingredients  COMPOSITION OF FEEDS  DM$  CP#*  GE k c a l / g *  a l f a l f a - brome hay  91.41  15.91  4.292  r o l l e d barley  87.45  n.52  4.227  soybean meal  87.67  54.00  4.695  flaked corn  86.67  8.29  4.254  * DM b a s i s  103 3. Results and Discussion Ewe performance as measured by ewe weight changes and lamb weaning weignts i s presented (Table 4). TABLE 4. EWE PERFORMANCE Sineli9S  Treatment DCP g/day DE Meal/day  1  227 5.5 6  Number of ewes  Twins 2 22?  6.6  4  3  272  272 6.6  8.4  6  6  6  Ewe weights (kg) postpartum weight  56.4  53.6  67.5  67.3  56 day weight  53.7  54.6  62.I  65.2  weight gain or loss  -2.7  +1.0  -5.4  -2.1  Lamb weights (kg)  4.03  4.13  3.78  56 day weight  20.87  21.70  18.03  17.84  weight gain  16.84  17.57  14.25  14.54  birthweight  0.301  average daily gain  0.314  3.30  0.260  0.255  Lamb Creep Feed Intake Average Daily Intake g (air dry)  132 (2M.2F)  82 (5M.1F)  104 (8M.4F)  86 (4M.8F)  There was no significant difference (p > 0.05) between the weight changes of the ewes with single or twin lambs or between levels of protein or energy i n the rations.  However, when comparing treatments 1 and 2  (ewes with single lambs) the ewes receiving the higher energy level tended to gain weight slightly while those on the lower level lost  104 weight s l i g h t l y when both groups were fed a s i m i l a r l e v e l of protein intake.  When comparing treatments 3 arid 4 (ewes suckling twin lambs)  the ewes r e c e i v i n g the higher l e v e l of energy l o s t l e s s weight than those on the lower l e v e l .  These r e s u l t s appear to show that 6.6 Meal and 227 g  DCP per ewe per day may be adequate f o r mature ewes suckling single lambs, while 8.4 Meal per ewe per day may be close to the energy requirement for ewes suckling twin lambs.  There was a h i g h l y s i g n i f i c a n t ( p ^ 0 0 5 ) o  d i f f e r e n c e between the ADG of single compared to twin lambs.  Both the  single and twin lambs appeared to respond to the higher energy l e v e l offered to t h e i r dams. The average d a i l y creep feed intake of the lambs were group averages and could not be analyzed s t a t i s t i c a l l y .  However, the mean  values indicated that the lambs of ewes on the lower l e v e l s of energy consumed more creep feed than those on the higher l e v e l .  This i s d i f -  f i c u l t to explain i n terms of the ADG of the lambs but may r e f l e c t the milk production of the ewes.  This would agree with the findings of  Wilson et a l . (1971) who reported that by increasing the energy content of the ewe's r a t i o n , the milk production also increased.  The r e s u l t s of  t h i s experiment would tend to show that as the energy content of the ewe's r a t i o n increased, the average d a i l y intake of creep feed decreased. would not agree with Gardner and Hogue (19&3) who concluded that the amount of creep feed consumed was e s s e n t i a l l y equal regardless of the energy l e v e l of the ewe's r a t i o n .  This  105 APPENDIX I I A comparison of mature ewes suckling single lambs when fed two l e v e l s of p r o t e i n a t a constant l e v e l of energy intake.  1.  Introduction The e f f e c t s of feeding two l e v e l s o f d i e t a r y p r o t e i n at a  constant l e v e l of energy intake on ewe performance and lamb growth rate were studied.  A nitrogen balance t r i a l was also carried out to determine  the d i g e s t i b i l i t y of the low p r o t e i n r a t i o n .  2.  Materials and Methods  Eighteen mature polled Dorset Horn ewes had been bred to rams o f the same breed and when they lambed were divided into two equal groups according to t h e i r postpartum weight and to the sex of t h e i r lambs The ewes were i n d i v i d u a l l y f e d grass hay at the l e v e l of 2.3$ of postpartum weight o f ewe plus 680 g o f one o f two concentrate supplements (Table l ) . When the lambs reached approximately 14 days o f age, they were offered a creep feed r a t i o n consisting of 1:1:1 r o l l e d barley, soybean meal, and r o l l e d wheat. A nitrogen balance t r i a l was carried out using three non-pregnant ewes weighing approximately 45 kg. They were f e d 340 g of low p r o t e i n concentrate mixture and 680 g of the chopped grass hay. This l e v e l of feed intake was adopted i n order that each ewe would receive approximately 50$ of the n u t r i e n t s offered to the l a c t a t i n g ewes.  106  TABLE 1 .  COMPOSITION OF SUPPLEMENTS Treatment  Ingredient  2  $  $  81  56  Soybean meal  9  34  Minerals *  8  8  Cobalt iodized salt  1  1  Vitamins **  1  1  Rolled barley  •mineral mixture 28$ Calcium 13$ Phosphorus 0 , 0 1 2 5 $ Copper 0,006$ Cobalt 0.05$  0,42$ 0.75$ 0.375$  3.  1  **vitamin mixture 4 3 5 , 0 0 0 IU vitamin A 8 7 , 0 0 0 IU vitamin D  1 , 7 0 0 IU vitamin E per kg mix  Fluorine  Manganese Iodine Iron  Results and Discussion Ewe performance as measured by ewe weight change and lamb  weaning weight i s presented (Table 2 ) .  There was no significant ( p > 0 . 0 5 )  difference i n the weight changes of the ewe receiving either the low or high protein ration.  The lamb performance also showed a non-significant  ( p > 0 . 0 5 ) difference between the two groups i n respect to ADG. However, there was a tendency for the lambs on treatment 2 to gain slightly faster than those on treatment 1 .  This i s probably due i n part to those lambs  consuming more creep feed sooner than those whose dams were on the lower level of protein (treatment l ) .  107 TABLE 2. EWE PERFORMANCE Treatment  1  2  11.1$ CP  l£.8$ CP  Postpartum weight  53.2  61.2  56 day weight  53.8  60.4  Weight change  +0.6  -0.8  Number of Ewes Ewe weights (kg;)  Lamb weights (kg) Birth weight  3.98  4.71  56 day weight  18.80  22.48  Weight gain  14.82  17.77  Average daily gain  O.265  0.317  9(4M,5F)  8*(6M,3F)  Creep feed consumption of lambs Number of lambs (sex) Start of creep feed consumption (days) Start of creep consumption (kg) Total feed intake (g) Average daily intake (g) * one lamb could not  3k  27  13.6  14.1  3966  676I  180  233  ;et into creep — too big  108 The digestibility coefficients for the low protein ration and nitrogen balance data are presented (Table 3). TABLE 3. DIGESTIBILITY AND NITROGEN BALANCE Treatment 1 (low protein ration) Ewe Number Mean  1  2  3  Dry Matter Digestibility $  71.09  70.15  72.20  71.15  Crude Protein Digestibility $  68.37  67.87  68.82  68.35  2.96  1.29  1.42  1.89  Nitrogen Retention g/ewe/day  Dry matter intake per ewe per day = 924.6 g Nitrogen intake per ewe per day = hay 9.72 g cone. 8.08 g 17.80 g  This digestibility t r i a l was carried out mainly to test the metabolism cages designed by the author.  The values however, do closely  represent the apparent d i g e s t i b i l i t y of dry matter and protein of the low protein ration fed to the ewes i n this experiment.  109 APPENDIX III Digestibility of Rapeseed and Soybean Meals 1.  Introduction I t would seem appropriate from the results obtained i n  Experiment I to determine the d i g e s t i b i l i t y of rapeseed and soybean meals i n order to explain more precisely why the rapeseed (treatment 2) and the soybean (treatment 3) rations had different digestibility values when the levels of intake were similar.  The object therefore, was to  feed the other two main ingredients (hay and barley alone) to sheep, determine their digestibility and then determine same for the respective protein supplement by difference. 2.  Materails and Methods Digestibility t r i a l s were conducted using three non-pregnant  ewes weighing approximately 43,5 kg.  Each ewe was fed 1020 g of a grass  hay similar to that fed to the pregnant ewes i n Experiment I. Digestibility t r i a l s were also conducted using three ram lambs weighing approximately 43 kg.  Each ram was fed 1,000  barley which had a protein content of 12.5$  g of whole  on a dry matter basis.  The balance procedure and the analysis of feeds and feces are located i n the general methods section of this report. 3.  Results and Discussion The digestibility coefficients for the two feeds are  presented (Table l ) .  110 TABLE 1. DIGESTIBILITY COEFFICIENTS Treatment Grass Hay Dry Matter Digestibility $ sheep 1 mean  2 3  Crude Protein Digestibility $ sheep 1 mean  2 3  Barley.  60.2 61.9  82.78 80.78 79.18 80.91  64.0  62.0  71.72 70.94  27.58 28.94 29.85 28.79  71.60  71.42  From the digestibility values (Table l ) of the grass hay and barley fed alone to sheep, the d i g e s t i b i l i t y of rapeseed meal and soybean^ meal were calculated as followssRation 2 (low rapeseed meal) had the following compositions (Table 2).  Ingredient  % of DM  Hay  66.7  Barley  17.3  Rapeseed meal  11.7  Minerals plus molasses Total  Determined CP $  5.9  CP provided  Determined digestibility of protein $  DCP provided  3.93  28.8  1.13  11.6  2.10  71.4  1.44  36.0  4.61  (3.52)  4.3 100  10.55  5.77  6.09  Therefore the digestibility of the rapeseed meal protein as calculated by difference was 3»52 •$ 4.6l = 76.4$.  Ill The digestibility of the soybean meal protein was calculated i n a similar manner and was found to be 85.6$. These values may be compared with the literature values of 82.3$ for rapeseed meal and 90.0$ for soybean meal, (NRC, 19^9)•  The results of this study support the find-  ing (Experiment I) that soybean meal appeared to have a higher digestib i l i t y than rapeseed meal when compared at a similar level of intake. o  The results also support the conclusion of Manns and Bowland (19^3 b) that rapeseed meal i n the diet decreases the d i g e s t i b i l i t y of nitrogen and dry matter when compared to soybean meal. It i s interesting to note the nitrogen retention figures obtained when the ewes were fed grass hay alone. of -3.19. -1.75. and -2.91«  Three determinations gave values  These figures show that grass hay of the  crude protein content fed, can not be used as the sole source of protein for any class of sheep.  112 APPENDIX IV Milk Production and Composition 1»  Materials and Methods Ten ewe lambs i n their 28th day of lactation were used to  estimate milk production and qtiality over a 24 hour period. were confined to their individual creep pens at 2 a.m..  Their lambs  At 6 and 10 a.m.  and at 2 and 6 p.m., the lambs were weighed to the nearest 5 grams, then allowed to suckle u n t i l they were no longer interested and immediately weighed again, giving the total milk produced i n each four hour period. At 10 p.m. each ewe was intravenously injected with 0.3 ml oxytocin, having a strength of 20 USP units/ml.  One quarter of each ewe's udder  was then milked out completely and a representative sample taken for analysis.  The samples were stored at 4° C u n t i l the following day when :  they were analyzed for milk constituents by the British Columbia Dairy Branch of the B.C... Department of Agriculture using automated infrared milk analyses techniques. 2. Results and Discussion Daily ewe milk production and composition as determined by average production i n four hour periods i n terms of both pregnancy and lactation treatment of the ewes i s presented (Table 1).  113 TABLE 1. MILK PRODUCTION AND COMPOSITION  Treatment  Number of ewes  1 HR-LR  2 HR-HR  2 LR-HR  1 LR-LR  4 LS-LS  Milk production Production 4 h r s . g T o t a l production 24 h r s . g  170  158  183  190  1020  948  1098  1140  196  1176  Milk Composition Fat $ T o t a l f a t 24 h r s . g Protein $  10.38  6.69  9.W)  9.02  8.87  95.88  85.51  113.97  76.27  104.31  4.46  5.01  4.37  4.11  4.31  45.49  47.50  47.98  46.85  50.69  5.36  5.16  5.13  5.25  5.26  5^.67  ^.92  56.33  59.85  61,86  Total protein 24 h r s . g Lactose $ T o t a l lactose 24 h r s . g  114 A summary of d a i l y ewe milk production and composition i n terms of l a c t a t i o n treatment only i s presented (Table 2). TABLE 2.  MILK PRODUCTION Al© COMPOSITION  Treatment  Number o f ewes  4 HR  2 LR  4 LS  Milk production Production 4 h r s . g  171  180  196  1023  1080  II76  T o t a l production  24 hrs. g Milk  Composition  Fat £  Total f a t 24 hrs. g P r o t e i n f>  9.70  8.05  8.87  99.74  86.08  104.31  4.69  4.29  47.74  46.17  5.15  5.31  52.63  57.26  4.31  T o t a l protein  24 hrs. g Lactose #  50.69 5.26  T o t a l lactose  24 hrs. g  61.86  Due to the f a c t that the treatment groups had only a small number of animals, treatment means are only i n d i c a t i o n s of the quantity and q u a l i t y of milk produced by ewe lambs. by Butterworth e t a l .  (1968).  The values are comparable to those obtained The high l e v e l of protein appeared to  increase the f a t content ($) of the milk. f i n d i n g s of Butterworth et a l .  (1968).  This would agree with the  APPENDIX V STATISTICAL ANALYSIS TABLES  116 II.  Analysis of Variance - Weight gain of ewes (pregnant ewe lambs f e d rapeseed meal Experiment I) Source  df  ss  Total  26  392.1  obs. F  F  0.374  3.63  Treatment  2  15<>4  7.70  Replicate  8  4?.4  5.93  16  329 o2  20.58  Residual  Since the observed F  0.374 i s l e s s  .05  ms  than the value F  .05 = 3.63,  i t may be concluded that there was no s i g n i f i c a n t d i f f e r e n c e between the weight gains of the ewes fed either r a t i o n 1, 2, or 3 during pregnancy.  12.  A n a l y s i s of Variance - Birthweight of single lambs (pregnant ewe lambs fed rapeseed meal Experiment I ) Source  df  ss  Total  26  48.3  Treatment  2  1.4  0.7  Replicate  8  14.4  1.8  16  32.5  2.0  Residual  Since the observed F 0.35  ms  obs. F  F  3.63  0.35  i s l e s s than the value F .05 =  .05  3.63,  i t may be concluded that there was no s i g n i f i c a n t d i f f e r e n c e between the birthweights of the single lambs born to ewes fed either r a t i o n 1, 2, or 3 during pregnancy.  117 I I 1.  Analysis of Variance - Weight change of ewes ( l a c t a t i n g ewe lambs fed rapeseed meal Experiment I I ) Source  df  ss  Total  26  1147.9  Treatment  2  Replicate Residual  ms  obs F  37.6  18.8  0.714  8  688.5  86,1  16  421.7  26.4  F  .05  3.63  Since the observed F 0.714 i s l e s s than the value F .05 = 3.63, i t may be concluded that there was no s i g n i f i c a n t d i f f e r e n c e between the weight changes of the ewes fed either r a t i o n 1, 2, or 3 during the l a c t a t i o n period.  I I 2o  Analysis of Variance - Average d a i l y gain of lambs by l a c t a t i o n treatment  only  ( l a c t a t i n g ewe lambs fed rapeseed meal Experiment I I ) Source  df  ss  Total  26  0.362  Treatment  2  0.008  0.004  Replicate  8  0.064  0.008  16  0.290  0.018  Residual  ms  obs. F  F .05  0.222  3.63  Since the observed F 0.222 i s l e s s than the value F .05 = 3.63, i t may be concluded that there was no s i g n i f i c a n t d i f f e r e n c e between the average d a i l y gain of the lambs when t h e i r dams xrere fed either r a t i o n s 1, 2, or 3 during l a c t a t i o n  118 II 3*  Analysis of Variance - Average daily intake of creep feed (lactating ewe lambs fed rapeseed meal Experiment II) Source  df  Total  26  286.1  Treatment  2  12.2  6.1  Replicate  8  62.1  7.8  16  211.8  Residual  ss  ms  obs. F  0.461  F .05  3.63  13.2  Since the observed F 0.461 i s less• than the value F .05 = 3.63, i t may be concluded that there was no significant difference between the average daily creep feed intake of the lambs whose dams were fed either ration 1, 2, or 3.  Analysis of Variance - Age at start of creep consumption (lactating ewe lambs fed rapeseed meal Experiment II) Source  df  ss  Total  26  1160  ms  obs. F  1.05  Treatment  2  80  40.0  Rsplicate  8  470  58.8  16  610  38.1  Residual  F .05  3.63  Since the observed F 1.05 i s less than the value F .05 = 3*63, i t may be concluded that there was no significant difference between the weight at the start of creep consumption of the lambs whose dams received ration 1, 2, or 3 during lactation.  119 III 1  0  Analysis of Variance - Lamb performance ( a l l concentrate r a t i o n s f o r lambs Experiment I I I )  .05  df  Total  47  187.5  Treatment  5  44.7  8.9  Process  2  40.1  20,1  Grain  1  2.8  2.8  4.1  NS  Process x Grain  2  1.8  9.0  2.64  NS  42  142.8  3.4  Residual Since observed F 5*9  ss  ms  Source  i s l a r j;er than the value F  may be concluded that there was  obs. F  F  5.9  .05 = 3.32,  3.32  **  it  a s i g n i f i c a n t d i f f e r e n c e between  the average d a i l y gain of the lambs fed either whole, r o l l e d , or pelleted g r a i n .  However, as can be seen above, there was  no  s i g n i f i c a n t d i f f e r e n c e between the average d a i l y gain of the lambs fed wheat or barley and there was no process x g r a i n i n t e r a c t i o n .  120 III 2.  Analysis of Variance - Protein Digestibility ( a l l concentrate rations for lambs Experiment III) ms  obs. F  F .05  Source  df  ss  Total  35  391.7  Treatment  11  315.6  28.7  9.1  2.3 *  Process  2  32.9  16.5  5.2  3.4 *  Grain  1  170.3  170.3  53.7  4.3 *  Level  1  59.9  59.9  18.9  4.3 *  L x G  1  11.0  11.0  3.5  4.3 NS  L x P  2  3.3  1.7  G x P  2  22.1  11.1  3.5  3.4 *  G x P x L  2  16.1  8.0  2.5  3c4 NS  24  76.0  3.2  Residual  Conclusions after completing Duncan's test 1.  ^11  NS  —  Processing influenced d i g e s t i b i l i t y of protein - pelleted r e l . to rolled.  2.  Grain influenced d i g e s t i b i l i t y of. barley ^ wheat.  3.  Level influenced d i g e s t i b i l i t y 600 > 1000 g/day.  4.  Grain x Process interaction - due to rolling}improving the DCP # of wheat and not barley.  121  I I I 3»  Analysis of Variance - Energy D i g e s t i b i l i t y ( a l l concentrate r a t i o n s Experiment I I I )  Source  df  Total  36  210.3  Treatment  11  163.4  Process  2  1.1  Grain  1  Level  ss  obs. F  ms  F  .05  2.24  **  < 1  NS:  NS  116.5  62.1  4.24  **  10.5  10.5  5.6  4.24  **  1  0.3  0.3  <1  NS  NS  L x P  2  10.5  5.3  2.81  3.39  NS  G x P  2  16.9  8.4  4.49  3.39  **  G x P x L  2  7.6  3.8  2.02  3.39  NS  25  46.9  1.9  14.9  7.92  < 1  116.5  1  L x G  Error  Conclusions  a f t e r completing  Duncan's t e s t  —  1.  Processing had no s i g n i f i c a n t e f f e c t on DE  2.  DE % wheat s i g n i f i c a n t l y > barley.  3.  Level of intake had a s i g n i f i c a n t e f f e c t on DE  4.  An i n t e r a c t i o n between grain and process was observed.  122  Analysis of Variance - Ewe weight change (mature ewes suckling single or twin lambs - Appendix I) df  Total  23  1956.5  Treatment  3  5^2.5  180.8  Replication  5  352.5  70.5  15  1061.5  70.8  Error  ss  ms  Source  obs. F  F .05  2.55  3.29  Since the observed F 2.55 i s less than the value F .05 = 3.29. i t may be concluded that there was no significant difference between the weight change of the ewes fed either ration 1, 2, 3. or 4.  Analysis of Variance - Average daily gain of lambs (mature ewes suckling single or twin lambs - Appendix I) Source  df  ss  Total  35  0.05  3 32  Treatment Residual  ms  obs. F  F .05  0.10  0.033  16.5  2.90  0.05  0.022  Since the observed F 16.5 i s greater than the value F .05 = 2.90, i t may be concluded that there was a significant difference tetween the average daily gain of single and twin lambs (Duncan's test).  

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