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Assessment of forage species and varieties for the central interior of British Columbia 1987

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ASSESSMENT OF FORAGE SPECIES AND VARIETIES FOR THE CENTRAL INTERIOR OF BRITISH COLUMBIA by ALLAN OSBORNE MCNEIL B. Sc. (A g r . ) , The U n i v e r s i t y of B r i t i s h Columbia, 1978. A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN THE FACULTY OF GRADUATE STUDIES (Animal Science) We accept t h i s t h e s i s as conforming to the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA NOVEMBER 1986 if?)ALLAN OSBORNE MCNEIL, 1986 .3 2 In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l l m e n t of the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r reference and study. I f u r t h e r agree that permission f o r extensive copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the head of my department or by h i s or her r e p r e s e n t a t i v e s . I t i s understood that copying or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l gain s h a l l not be allowed without my w r i t t e n permission. Department of Animal Science The U n i v e r s i t y of B r i t i s h Columbia 1956 Main M a l l Vancouver, Canada V6T 1Y3 ABSTRACT 1982 experiments were conducted to examine s e v e r a l aspects of forage q u a l i t y i n r e l a t i o n to animal n u t r i t i o n , i n c l u d i n g the d i f f e r e n c e s i n q u a l i t y between forage types (legumes or g r a s s e s ) , species and v a r i e t i e s ; between years; between two hay mixes; and between three harvest dates. In a d d i t i o n , the importance of q u a l i t y r e l a t i v e to y i e l d i s examined. In the f i r s t experiment, a c i d detergent f i b r e , n e u t r a l detergent f i b r e , crude p r o t e i n , and nylon bag dry matter disappearance determinations were used to assess the v a r i a t i o n i n q u a l i t y between forage types, species and v a r i e t i e s , and between years. In the second, v o l u n t a r y dry matter i n t a k e and d i g e s t i b i l i t y r e s u l t s were used to assess the v a r i a t i o n i n q u a l i t y between hay mixes and harvest dates. The r e s u l t s of the f i r s t experiment i n d i c a t e that the legumes were of higher q u a l i t y than the grasses; red and a l s i k e c l o v e r were of higher q u a l i t y than a l f a l f a , and orchardgrass was of higher q u a l i t y than timothy. With the exception of red c l o v e r s , where Lakeland and P a c i f i c v a r i e t i e s were of higher q u a l i t y than Altaswede, there was l i t t l e d i f f e r e n c e i n q u a l i t y between v a r i e t i e s w i t h i n a s p e c i e s . N e u t r a l detergent f i b r e a n a l y s i s r e s u l t s suggest a d i f f e r e n c e i n i n t a k e between forages grown i n d i f f e r e n t years w h i l e a c i d detergent f i b r e a n a l y s i s r e s u l t s i n d i c a t e 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 would be expected between years. The r e s u l t s of the second experiment i n d i c a t e there was a d i f f e r e n c e i n q u a l i t y between forage mixtures (the e a r l y maturing mixture was b e s t ) , and harvests ( e a r l y and mid bloom harvests were b e t t e r than the l a t e bloom h a r v e s t ) . The parameter w i t h the l a r g e s t v a r i a b i l i t y was y i e l d . D i f f e r e n c e s were greater between years than between types and species (the c l o v e r s h i g h e s t , a l f a l f a and timothy i n t e r m e d i a t e , and orchardgrass lowest) w i t h the l e a s t v a r i a t i o n occuring between v a r i e t i e s w i t h i n s p e c i e s . The red clover-timothy ( l a t e maturing) forage mixture was the highest y i e l d i n g . W i t h i n forage mixtures the f u l l bloom harvest (100% bloom of the legume component) had the highest y i e l d s . Since y i e l d was more v a r i a b l e than the q u a l i t y parameters s t u d i e d , i t was concluded that the most important c o n s i d e r a t i o n when s e l e c t i n g a forage mixture was y i e l d . Since there tended to be l i t t l e d i f f e r e n c e i n q u a l i t y parameters between v a r i e t i e s w i t h i n a s p e c i e s , s e l e c t i n g the highest y i e l d i n g combination would provide the l a r g e s t amount of useable n u t r i e n t s per hectare of land base. TABLE OF CONTENTS ABSTRACT i i TABLE OF CONTENTS i v LIST OF TABLES v i ACKNOWLEDGEMENTS v i i i CHAPTER 1 - INTRODUCTION 1 CHAPTER 2 - LITERATURE REVIEW 2.1 FACTORS AFFECTING FEED INTAKE 3 2.1.1 INTAKE REGULATION 3 2.1.2 ANIMAL FACTORS AFFECTING INTAKE 5 2.1.3 PLANT FACTORS AFFECTING INTAKE 7 2.1.3.1 FORAGE TYPE, SPECIES AND VARIETY 8 2.1.3.2 PLANT MATURITY AND DATE OF CUTTING 9 2.1.3.3 CHEMICAL COMPOSITION 10 2.1.3.4 LEAF AND STEM 12 2.1.3.5 CHOPPING AND PELLETING 12 2.2 FACTORS AFFECTING FEED DIGESTIBILITY 13 2.2.1 ANIMAL FACTORS AFFECTING DIGESTIBILITY 13 2.2.2 PLANT FACTORS AFFECTING DIGESTIBILITY 14 2.2.2.1 FORAGE TYPE, SPECIES AND VARIETY 14 2.2.2.2 PLANT MATURITY AND DATE OF CUTTING 16 2.2.2.3 LEAF AND STEM 17 2.2.2.4 CHOPPING AND PELLETING 17 2.2.2.5 CHEMICAL TREATMENTS 18 2.3 ENVIRONMENTAL FACTORS AFFECTING INTAKE AND DIGESTIBILITY.18 2.4 TROPICAL VERSUS TEMPERATE GRASSES 20 2.5 LABORATORY METHODS OF ASSESSING FORAGE VALUE 21 2.5.1 PROXIMATE ANALYSIS 21 2.5.2 IN VITRO DRY MATTER DISAPPEARANCE 23 2.5.3 NYLON BAG DRY MATTER DISAPPEARANCE 24 2.5.4 CHEMICAL SYSTEMS 28 2.5.4.1 VAN SOEST FIBRE SYSTEM 28 2.5.4.2 FONNESBECK SYSTEM 33 2.5.4.3 SOUTHGATE SYSTEM 34 2.6 SHEEP AS MODELS FOR CATTLE 35 CHAPTER 3 - THE VARIETY TRIAL 3.1 MATERIALS AND METHODS 36 3.1.2 DETERMINATIONS 39 3.1.1 EXPERIMENTAL DESIGN AND STATISTICAL ANALYSIS 41 3.1.3 ASSESSMENT OF FEEDING VALUE 45 3.1.4 INTEGRATION OF FORAGE QUALITY AND YIELD 45 3.2 RESULTS 46 3.2.1 YIELD ...46 3.2.2 CRUDE PROTEIN 50 3.2.3 NEUTRAL DETERGENT FIBRE 54 3.2.4 ACID DETERGENT FIBRE 58 3.2.5 NYLON BAG DRY MATTER DISAPPEARANCE 62 3.2.6 ASSESSMENT OF FEEDING VALUE 68 3.2.7 INTEGRATION OF FORAGE QUALITY AND YIELD 70 3.2.8 NBDMD RESULTS USING PLOTS OF ANIMALS AS REPLICATES..73 3.2.9 WEATHER 76 3.3 DISCUSSION 78 3.3.1 YIELD 78 3.3.2 QUALITY DETERMINATIONS 80 3.3.3 ASSESSMENT OF FORAGE QUALITY 86 3.3.4 ASSESSMENT OF FEEDING VALUE 88 3.3.5 INTEGRATION OF FORAGE QUALITY AND YIELD 89 3.3.6 NBDMD RESULTS USING PLOTS OR ANIMALS AS REPLICATES..90 CHAPTER 4 - THE FEEDING TRIAL 4.1 MATERIALS AND METHODS 91 4.1.1 FORAGES 91 4.1.2 EXPERIMENTAL DESIGN AND STATISITCAL ANALYSIS 93 4.1.3 INTAKE AND DIGESTIBILITY TRIAL METHODOLOGY 94 4.1.4 ANIMAL MANAGEMENT 95 4.1.5 ANALYTICAL PROCEDURES 95 4.2 RESULTS 96 4.3 DISCUSSION 107 4.3.1 INTAKE AND DIGESTIBILITY 107 4.3.2 UNCONTROLLED FACTORS 110 4.3.3 LINEAR AND QUADRATIC REGRESSION ANALYSIS 112 4.3.4 INTEGRATING RESULTS WITH YIELD 113 4.3.5 COMPARISON WITH VARIETY TRIAL RESULTS 113 CHAPTER 5 - GENERAL DISCUSSION AND CONCLUSIONS 115 CHAPTER 6 - RECOMMENDATIONS 119 REFERENCES 120 APPENDIX 131 LIST OF TABLES Chapter 3 Table 3.1 Species and V a r i e t i e s Used i n T r i a l 37 Table 3.2 Harvest Dates f o r Samples of the V a r i e t y T r i a l 38 Table 3.3 Least Square Means ± SEM of Forage Y i e l d s by Type and Species 47 Table 3.4 Least Square Means ± SEM of Forage Y i e l d s by V a r i e t y 49 Table 3.5 Least Square Means ± SEM.of Y i e l d , CP, NDF, ADF, and NBDMD by Year 51 Table 3.6 Least Square Means ± SEM of Crude P r o t e i n L e v e l s by Type and Species 52 Table 3.7 Least Square Means ± SEM of Crude P r o t e i n L e v e l s by V a r i e t y 53 Table 3.8 Least Square Means ± SEM of N e u t r a l Detergent F i b r e L e v e l s by Type and Species 55 Table 3.9 Least Square Means ± SEM of N e u t r a l Detergent F i b r e L e v e l s by V a r i e t y 57 Table 3.10 Least Square Means ± SEM of A c i d Detergent F i b r e L e v e l s by Type and Species 59 Table 3.11 Least Square Means ± SEM of A c i d Detergent F i b r e L e v e l s by V a r i e t y 61 Table 3.12 Least Square Means ± SEM of Nylon Bag Dry Matter Disappearance Levels by Type and Species 63 Table 3.13 Least Square Means ± SEM of Nylon Bag Dry Matter Disappearance Levels by V a r i e t y 64 Table 3.14 Least Square Means ± SEM of Nylon Bag Dry Matter Disappearance L e v e l s by Year 66 Table 3.15 Least Square Means ± SEM of Nylong Bag Dry Matter Disappearance L e v e l s by Animal 67 Table 3.16 E s t i m a t i o n of Dry Matter Intake (DMI), D i g e s t i b l e Dry Matter (DDM) and Feeding Value Index (FVI) 69 Table 3.17 Least Square Means ± SEM of D i g e s t i b l e Energy Y i e l d s by Type and Species 71 Table 3.18 Least Square Means ± SEM of D i g e s t i b l e Energy Y i e l d s by V a r i e t y 72 Table 3.19 Least Square Means ± SEM of Crude P r o t e i n Y i e l d s by Type and Species 74 Table 3.20 Least Square Means ± SEM of Crude P r o t e i n Y i e l d s by V a r i e t y 75 Table 3.21 Least Square Means ± SEM of Nylon Bag Dry Matter Disappearance 77 Chapter 4 Table 4.1 Harvest Date and Y i e l d of Test Forages 92 Table 4.2 N u t r i e n t Composition of Hay Mixes (Dry Matter Basis)..97 Table 4.3 P r o p o r t i o n of Grass and Legume i n Each Hay Mix 98 Table 4.4 Means of Intake Parameters f o r E a r l y Maturing and Late Maturing Forage Mixes 100 Table 4.5 Means of D i g e s t i b i l i t y Parameters f o r E a r l y Maturing and Late Maturing Forage Mixes 101 Table 4.6 Means of Intake Parameters f o r E a r l y , Mid and F u l l Bloom Harvests... 102 Table 4.7 Means of D i g e s t i b i l t y Parameters f o r E a r l y , Mid and F u l l Bloom Harvests 103 Table 4.8 C o e f f i c i e n t s of Determination f o r Simple and M u l t i p l e Factor Models 105 Table 4.9 Hay Mix, Harvest Date and Y i e l d of Test Forages.... 106 ACKNOWLEDGEMENTS I would l i k e to express my a p p r e c i a t i o n to Dr. L y l e Rode f o r h i s as s i s t a n c e and guidance over the past three y e a r s , and to A g r i c u l t u r e Canada f o r the use of f a c i l i t i e s . I would a l s o l i k e to thank Dr. Malcolm T a i t f o r p r o v i d i n g d i r e c t i o n and a s s i s t a n c e . Further help from J . A. P e l t e r , J . N. T i n g l e , B. Wikeem w i t h thoughts and resources was a l s o g r a t e f u l l y acknowledged. F i n a l l y , I would l i k e to thank Dr. J . Basarab and A l b e r t a A g r i c u l t u r e f o r a s s i s t a n c e w i t h and s t a t i s t i c a l a n a l y s i s . I would l i k e to pay s p e c i a l t r i b u t e to Regina who has given up ho l i d a y s and weekends to see t h i s p r o j e c t completed and to thank her f o r her patience and support throughout. CHAPTER 1 INTRODUCTION A g r i c u l t u r e i n the C e n t r a l I n t e r i o r r e g i o n of B r i t i s h Columbia was extensive i n nature and was based mainly on forage crops intended f o r l i v e s t o c k consumption. The i n d u s t r y was l o c a t e d along r i v e r v a l l e y s possessing i n d i v i d u a l microclimates w i t h growing c o n d i t i o n s that d i f f e r s u f f i c i e n t l y from other regions to r e q u i r e l o c a l forage crop e v a l u a t i o n . S e v e r a l p r o j e c t s have been undertaken to evaluate forage species and v a r i e t i e s i n the region (Waldern and Burns, 1964; T i n g l e and Dawley, 1974; T i n g l e and E l l i o t , 1975; Waldie et_ a l . , 1983). These t r i a l s examined p r o d u c t i v i t y of species and v a r i e t i e s as measured by y i e l d and in v o l v e d few animal r e l a t e d parameters. A d d i t i o n a l l a b o r a t o r y techniques are a v a i l a b l e that f u r t h e r e l u c i d a t e the s u i t a b i l i t y of those species and v a r i e t i e s on t e s t f o r animal production. With these p o i n t s i n mind the o v e r a l l o b j e c t i v e of t h i s study was to assess the q u a l i t y of s e l e c t e d forages grown i n the C e n t r a l I n t e r i o r of B r i t i s h Columbia i n terms of animal production i n order to o b t a i n i n f o r m a t i o n upon which b e t t e r l i v e s t o c k recommendations could be based. To meet t h i s o b j e c t i v e two p r o j e c t s were undertaken. The f i r s t p r o j e c t (the V a r i e t y T r i a l ) i n v o l v e d a n a l y s i s of four v a r i e t i e s each of orchard grass ( D a c t y l i s glomerata L.) timothy ( Phleum pratense L.) and a l f a l f a ( Medicago s a t i v a L.) , one v a r i e t y of a l s i k e c l o v e r ( T r i f o l i u m hybridum L.) and three v a r i e t i e s of red c l o v e r ( T r i f o l i u m pratense L . ) . Samples of each v a r i e t y were c o l l e c t e d over three years as part of the B.C. Seed Crop E v a l u a t i o n P r o j e c t (1981-1983). Each forage p l o t was harvested at the p h e n o l o g i c a l stage considered optimum f o r forage q u a l i t y . Standing crop was then determined and the samples stored. Determinations c a r r i e d out i n the V a r i e t y T r i a l i n c l u d e d crude p r o t e i n (CP), a c i d detergent f i b r e (ADF), n e u t r a l detergent f i b r e (NDF), and nylon bag dry matter disappearance (NBDMD). The s p e c i f i c o b j e c t i v e s of the v a r i e t y t r i a l were: 1) to assess the v a r i a t i o n i n the n u t r i t i o n a l q u a l i t y between forage species and v a r i e t i e s w i t h i n s p e c i e s , and; 2) to assess the v a r i a t i o n i n the n u t r i t i o n a l q u a l i t y of forage species and v a r i e t i e s between years based on l a b o r a t o r y a n a l y t i c a l procedures. The second p r o j e c t (The Feeding T r i a l ) i n v o l v e d an assessment of two grass-legume mixtures harvested at e a r l y , mid and f u l l bloom of the legume component. The f i r s t mixture c o n s i s t e d of T e t r a a l s i k e c l o v e r , Toro timothy and Manchar smooth bromegrass ( Bromus inermis L.) i n a f o r m u l a t i o n intended to mature e a r l i e r i n the growing season than the second mixture which c o n s i s t e d of Altaswede red c l o v e r and Climax timothy. Dry matter i n t a k e (DMI) and dry matter d i g e s t i b i l i t y (DMD) of each mixture were determined. The s p e c i f i c o b j e c t i v e s of the feeding t r i a l were: 1) to assess the e f f e c t of an e a r l y and l a t e maturing forage mixture on v o l u n t a r y feed i n t a k e and d i g e s t i b i l i t y , and; 2) to assess the e f f e c t of i n c r e a s i n g m aturity of each forage mixture on v o l u n t a r y feed i n t a k e and d i g e s t i b i l t y . CHAPTER 2 LITERATURE, REVIEW 2.1 FACTORS AFFECTING FEED INTAKE Ruminant animals are able to convert p l a n t m a t e r i a l s that are not w e l l d i g ested by man i n t o food. Thus, they not compete d i r e c t l y w i t h man f o r food rescources (Van Soest, 1982). The animal production p o t e n t i a l of these p l a n t m a t e r i a l s was determined by a complex i n t e r a c t i o n between the c o n s t i t u e n t s of the feed, the rumen m i c r o b i a l p o p u l a t i o n , the p h y s i o l o g i c a l s t a t e of the animal and the environment. The animal production p o t e n t i a l (or feeding value) of a forage was a f u n c t i o n of feed i n t a k e and feed u t i l i z a t i o n . Apparent d i g e s t i b i l i t y was a major component of feed u t i l i z a t i o n (or n u t r i t i v e value) although other f a c t o r s such as e f f i c i e n c y of n u t r i e n t u t i l i z a t i o n are a l s o important ( U l y a t t , 1973). I t was d i f f i c u l t to r e s o l v e the r e l a t i v e importance of v o l u n t a r y i n t a k e and n u t r i t i v e value i n determining the o v e r a l l feeding value of a forage because the two feed parameters are c o r r e l a t e d - n u t r i t i v e value being a production response per u n i t i n t a k e . The r e s u l t s of U l y a t t (1973) i n d i c a t e d that d i g e s t i b i l i t y and i n t a k e are each a s s o c i a t e d w i t h approximately 50Z of the v a r i a t i o n i n l i v e weight gain of t e s t animals. The f o l l o w i n g s e c t i o n of the l i t e r a t u r e review w i l l cover the f a c t o r s c o n t r o l l i n g and a f f e c t i n g i n t a k e and d i g e s t i b i l i t y and the i n t e r - r e l a t i o n s h i p between these feed q u a l i t y parameters. 2.1.1 INTAKE REGULATION Jones (1972) i n d i c a t e d i n h i s review paper that the mechanisms of ruminant feed i n t a k e r e g u l a t i o n are complex and not w e l l understood. These mechanisms have evolved so that a c e r t a i n energy balance was main- ta i n e d that v a r i e s w i t h the productive s t a t u s of the animal ( B a i l e and D e l l a - F e r a , 1981). There i s evidence that the p a r t i c u l a r p h y s i o l o g i c a l mechanisms c o n t r o l l i n g i n t a k e w i l l vary depending on the q u a l i t y of the feed. As d i g e s t i b l i t y i s increased feed consumption w i l l r i s e to a p o i n t where the animals energy requirements are met. Above t h i s p o i n t i n t a k e i s c o n t r o l l e d by metabolic f a c t o r s , and as n u t r i t i v e value increases f u r t h e r feed i n t a k e decreases s i n c e l e s s i s r e q u i r e d to meet the d e s i r e d energy balance. Below the p o i n t where energy requirements are met other f a c t o r s such as "rumen f i l l " l i m i t i n t a k e . Conrad (1966) suggested that w i t h d a i r y cows t h i s p o i n t was at about 66% dry matter d i g e s t i b i l i t y . D e l l a - F e r a and B a i l i e (1984) i n d i c a t e d that the v a r i o u s f a c t o r s c o n t r o l l i n g i n t a k e are i n t e g r a t e d i n the hypothalamus but the a c t u a l neurochemical events are not w e l l understood. Feed i n t a k e may be mediated by chemostatic or thermostatic mechanisms ( B a i l i e and D e l l a - F e r a , v 1981) such as o s m o l a r i t y of body f l u i d s , rumen pH and v o l a t i l e f a t t y a c i d s but "because changes of hypothalamic and surface temperatures during feeding are r e l a t e d more to n o n s p e c i f i c a c t i v i t y than to feeding there seems to be l i t t l e evidence that temperature changes per se act under most c o n d i t i o n s as a s i g n a l f o r the hunger-satiety system". Feed i n t a k e was a l s o c o n t r o l l e d by the p h y s i c a l c a p a c i t y of the alimentary t r a c t , the r a t e of d i g e s t i o n and the r a t e at which undigested residues are reduced i n s i z e before they can move out of the rumen (Bines, 1971). P h y s i c a l r e g u l a t i o n of food i n t a k e probably i n v o l v e s s t r e t c h receptors i n the w a l l s of the rumen and i n t e s t i n e s but the exact nature and l o c a t i o n of these are not known ( B a i l e and D e l l a - F e r a , 1981). The p r i n c i p l e f a c t o r determining rumen cap a c i t y i s the s i z e of the animal (Bines, 1971), thus, when food of r e l a t i v e l y low d i g e s t i b i l i t y i s provided animal i n t a k e i s broadly r e l a t e d to l i v e w e i g h t . Disappearance from the t o t a l t r a c t a l s o a f f e c t s i n t a k e ( M e i j s , 1981). The r a t e of disappearance of d i g e s t a from the rumen was a f u n c t i o n of r a t e of breakdown by the a c t i o n of both m i c r o b i a l fermentation and mechanical a c t i v i t y ; i n c l u d i n g chewing, rumination and muscular c o n t r a c t i o n of the gut. The r e l a t i o n s h i p between i n t a k e and d i g e s t a disappearance was r e f l e c t e d i n the r e l a t i o n s h i p between v o l u n t a r y i n t a k e and d i g e s t i b i l i t y of v a r i o u s roughages. M e i j s (1981) concluded there was a strong r e l a t i o n s h i p between d i g e s t i b i l i t y and feed i n t a k e . The p o i n t at which food i n t a k e r e g u l a t i o n moves from p h y s i c a l to metabolic f a c t o r s depends on the type of feed, p h y s i o l o g i c a l s t a t u s of the animal and the energy c o n c e n t r a t i o n per u n i t of d i e t volume. 2.1.2 ANIMAL FACTORS AFFECTING INTAKE While animal i n t a k e i s regulated by p h y s i c a l and metabolic f a c t o r s , other f a c t o r s such as sensory cues, sex, age and weight, breed, l a c t a t i o n , pregnancy, body composition and e x e r c i s e a l s o p l a y an important p a r t i n how much was consumed. Ruminant animals used sensory clues i n c l u d i n g g u s t a t o r y , o l f a c t o r y and t a c t i l e s t i m u l a t i o n but not v i s i o n f o r s e l e c t i o n of feed s i n c e sheep f i t t e d w i t h b l i n d e r s had the same feed preference ranking as s i g h t e d sheep ( B a i l e and Forbes, 1974). Evidence of the o l f a c t o r y e f f e c t s was shown by Arnold et a l . (1980) i n which the v o l u n t a r y i n t a k e of hay by normal sheep was s i g n i f i c a n t l y increased by the odor of b u t y r i c a c i d and amyl acetate and depressed by the odor of coumarin and g l y c i n e . Anosmic sheep were unaffected and o v e r a l l had higher intakes than normal sheep f o r those compounds t e s t e d . Further evidence of the e f f e c t of s m e l l was r e j e c t i o n of feces contaminated herbage by c a t t l e ( M e i j s , 1981). Other researchers have noted that i n t a k e was reduced when the r a t i o n contains a high percentage of f i n e p a r t i c l e s . P a r t of t h i s r e d u c t i o n may be a t t r i b u t e d to reduced p a l a t a b i l i t y of the feed (Van Soest, 1982). Aderibigbe et_ a l . (1982) speculated that there were animal sex r e l a t e d d i f f e r e n c e s i n the animal's preference f o r four v a r i e t i e s of ryegrass. Sex d i f f e r e n c e s i n preference were seen i n s e v e r a l instances i n deer (Church, 1979) where bucks showed a stronger preference f o r sodium acetate than does. Owens et a l . (1985) found that o v e r a l l feed i n t a k e of beef s t e e r s was 2.8% higher than beef h e i f e r s i n a study of 745 d i f f e r e n t s e t s of pens of 50 c a t t l e or more. Owens et^ a l . (1985) found that breed had an e f f e c t on i n t a k e w i t h d a i r y breed s t e e r s e a t i n g more than beef breed s t e e r s w i t h a mean d i f f e r e n c e of 17% during each 28 day study p e r i o d , although t h i s may be due to body weight more than breed. B l a x t e r et_ a l . (1961) a l s o noted a d i f f e r e n c e i n i n t a k e between breeds of sheep, however, Weston (1982) i n d i c a t e d that i n most s t u d i e s of v o l u n t a r y feed i n t a k e d i f f e r e n c e s between breeds and s t r a i n s more care i s r e q u i r e d i n the s e l e c t i o n and p r e p a r a t i o n of the experimental animals. Thus, the data may not r e l i a b l y i n d i c a t e p o p u l a t i o n means. D i f f e r e n c e s i n i n t a k e due to sex and breed may be a s s o c i a t e d w i t h d i f f e r e n c e s i n the i n i t i a l weight of c a t t l e (Owens et_ a l _ . , 1985). S t a r t i n g weights when growing c a t t l e were admitted to a f e e d l o t were higher f o r d a i r y than beef s t e e r s and beef s t e e r s were higher than beef h e i f e r s . They noted that f o r a given weight, feed i n t a k e d i f f e r e n c e s by beef s t e e r s and h e i f e r s was l e s s than one percent. Another f a c t o r a f f e c t i n g i n t a k e was stage of pregnancy. In l a t e pregnancy, Campling (1966) found that the pregnant monozygotic twins ate l e s s hay than t h e i r non-pregnant s i s t e r s . Weston (1982) noted that the decrease i n feed consumption was not confined to d i e t s l i m i t e d i n i n t a k e by p h y s i c a l f a c t o r s but a l s o by metabolic f a c t o r s . He goes on to say that the reason feed i n t a k e f a l l s was not e s t a b l i s h e d , although the upward displacement of the v e n t r a l rumen w a l l reduced rumen volume, and may be a f a c t o r . Constant feed intakes have been recorded w i t h a 30% decrease i n rumen volume and increased estrogen s e c r e t i o n may a l s o be a f a c t o r . In many cases, pregnancy and l a c t a t i o n are confounded making i t d i f f i c u l t to d i f f e r e n t i a t e between the two p h y s i o l o g i c a l s t a t e s . Campling (1966) noted that l a c t a t i o n had a much greater e f f e c t on i n t a k e than pregnancy w i t h the l a c t a t i n g d a i r y cow e a t i n g 29% more hay than the dry, non-pregnant animal. Intake lagged s e v e r a l weeks behind the increase i n m i l k y i e l d . S i m i l a r r e s u l t s have been noted i n ewes (Dulphy et a l . , 1980). Weston (1982) s t a t e d that no c l e a r q u a n t i t a t i v e r e l a t i o n s h i p e x i s t s between v o l u n t a r y consumption and body composition even though there was evidence that f a t ruminants eat l e s s than t h i n ones ( B a i l e and Forbes, 1974). During l a c t a t i o n i n d a i r y cows and ewes, v o l u n t a r y feed inta k e tends to be i n v e r s e l y r e l a t e d to body f a t content. Other s t u d i e s have noted no change i n Intake between heavier and l i g h t e r mature animals. F i n a l l y , B a i l e and Forbes (1974) i n d i c a t e that e x e r c i s e can have a s i g n i f i c a n t e f f e c t on i n t a k e w i t h g r a z i n g animals r e q u i r i n g s u b s t a n t i a l l y more energy f o r maintenance than s t a l l fed animals. Animals tend to compensate f o r increased requirements by e a t i n g more. 2.1.3 PLANT FACTORS AFFECTING INTAKE In a d d i t i o n to the many animal r e l a t e d f a c t o r s that have an impact on i n t a k e of forages, there are a number of p l a n t f a c t o r s that may a f f e c t i n t a k e . These i n c l u d e p l a n t genus, species and v a r i e t y ; p h e n o l o g i c a l stage at harvest; date of h a r v e s t ; p l a n t p a r t ( l e a f or stem); and chemical composition. Minson (1982) i n d i c a t e d that the main f a c t o r s c o n t r o l l i n g animal i n t a k e was the p r o p o r t i o n of u n d i g e s t i b l e residues i n the feeds, residue t r a n s i t time throughout the rumen and the s i z e of the rumen. Feeds d i f f e r i n the time r e q u i r e d f o r them to be broken down to p a r t i c l e s s m all enough to escape from the rumen and these d i f f e r e n c e s , to v a r y i n g degrees, are i n f l u e n c e d by the f a c t o r s discussed below. These f a c t o r s a l s o a f f e c t the r e l a t i o n s h i p between i n t a k e and d i g e s t i b i l i t y f o r v a r i o u s feeds. 2.1.3.1 FORAGE TYPE, SPECIES AND VARIETY I t has been recognized f o r some time that legumes are eaten i n greater q u a n t i t i e s than grasses of s i m i l a r energy d i g e s t i b i l i t y (Minson, 1982). Troelson and Campbell (1969) showed that the i n t a k e of a l f a l f a hay was about 10% higher than that of the grass species s t u d i e d . Thornton and Minson (1973) found that the mean v o l u n t a r y i n t a k e of organic matter from a legume d i e t was higher than that of the grass d i e t . The r e t e n t i o n time i n the rumen was probably a major f a c t o r c o n t r i b u t i n g to the higher i n t a k e of legume. The grasses were r e t a i n e d 17% longer i n the rumen wh i l e the v o l u n t a r y i n t a k e of legumes was 282 higher than grasses when d i g e s t i b i l i t y of both was 60%. Walters (1971) found t h a t , at the same l e v e l of d i g e s t i b i l i t y , there were d i f f e r e n c e s i n i n t a k e of orchardgrass, t a l l fescue ( Festuca arundinacea Schreb.), p e r e n n i a l ryegrass ( Lolium perenne L.) and timothy. Troelson and Campbell (1969) a l s o noted that reed canary grass was lower i n dry matter i n t a k e (DMI) than e i t h e r c r e s t e d wheatgrass, bromegrass or Russian w i l d ryegrass at s i m i l a r dry matter d i g e s t i b i l i t i e s (DMD). Walters (1971) showed t h a t , at the mean l e v e l of d i g e s t i b i l i t y f o r those grasses he examined, the grasses were at d i f f e r e n t stages of growth w i t h d i f f e r e n t p r o p o r t i o n s of l e a f and stem. Meaningful comparisons between species are o f t e n confounded by morphological and anatomical d i f f e r e n c e s (Norton, 1982). D i g e s t i b i l i t y , r a t e of d i g e s t i o n , chemical f a c t o r s , p h y s i c a l f a c t o r s and e x t e r n a l f a c t o r s such as mold may a l s o i n f l u e n c e d i f f e r e n c e s i n in t a k e between forage species (Minson et^ a l . , 1964). Seoane et^ a l . (1981) found the in t a k e of Bounty timothy to be great e r than that of Champ and Climax t i m o t h i e s . Walters (1971) a l s o found d i f f e r e n c e s i n in t a k e between orchard grass, p e r e n n i a l ryegrass and timothy v a r i e t i e s measured at the same d i g e s t i b i l i t y . D i f f e r e n c e s i n in t a k e between v a r i e t i e s was not as wide as that between d i f f e r e n t s p e c i e s . I t was noted that the e a r l i e r heading v a r i e t i e s had s i g n i f i c a n t l y higher i n t a k e s than the l a t e r heading v a r i e t i e s . Troelson and Campbell (1969) reported that e a r l y i n the season, DMI was s i m i l a r f o r two v a r i e t i e s of a l f a l f a w h i l e l a t e r i n the season there were d i f f e r e n c e s at s i m i l a r d i g e s t i b i l i t i e s . The authors a t t r i b u t e d t h i s to v a r i a t i o n s i n l e a f i n e s s . 2.1.3.2 PLANT MATURITY AND DATE OF CUTTING Troelson and Campbell (1969) found that as the p l a n t matures, intak e was reduced. The authors i n d i c a t e d t h i s was r e l a t e d to decreasing d i g e s t i b i l i t y . Walters (1971) reported that d i g e s t i b i l i t y accounted f o r a major p o r t i o n of the v a r i a b i l i t y of in t a k e i n f i r s t cut forage. Minson et a l . (1964) a l s o showed a general f a l l i n i n t a k e as herbage d i g e s t i b i l i t y decreased w i t h f i r s t harvest being done s u c c e s s f u l l y l a t e r i n the growing season. When a forage was harvested two or more times during the growing season, the number of days to harvest was a major i n d i c a t i o n of n u t r i t i o n a l value (Walters, 1971). Troelson and Campbell (1969) reported that l e a f i n e s s d e c l i n e s w i t h advancing maturity reducing the a v a i l a b i l i t y of crude p r o t e i n and s o l u b l e carbohydrates. The changing l e a f to stem r a t i o may a l s o be a f a c t o r i n decreasing n u t r i t i v e v a l u e . A k i n (1982) pointed out that the t o t a l c e l l w a l l c o n s t i t u e n t s of forage increases as the p l a n t matures. In grasses, q u a l i t y was reduced w i t h the t r a n s l o c a t i o n of s o l u b l e carbohydrates from the stem and leaves to the i n f l o r e s c e n c e r e s u l t i n g i n increased l i g n i f i c a t i o n and decreased l e a f to stem r a t i o . The drop i n i n t a k e was l e s s i n legumes than grasses due to a smaller drop i n q u a l i t y (Troelson and Campbell, 1971) even though intak e of a l f a l f a decreased w i t h i n c r e a s i n g maturity i n conj u n c t i o n w i t h decreasing energy (Heaney, 1970). 2.1.3.3 CHEMICAL COMPOSITION As the p l a n t matures, an increase i n the f i b r e l e v e l u s u a l l y occurs r e s u l t i n g i n a re d u c t i o n i n p r o t e i n and n o n - s t r u c t u r a l carbohydrates w i t h an a s s o c i a t e d r e d u c t i o n i n in t a k e and d i g e s t i b i l i t y (Minson, 1982). As c e l l w a l l c o n s t i t u e n t l e v e l s i n c r e a s e , i n t a k e d e c l i n e s (Van Soest, 1965). In forages w i t h a high f i b r e l e v e l i n the c e l l w a l l , i n t a k e was r e l a t e d more to the i n d i v i d u a l animal's energy requirement. C e l l w a l l c o n s t i t u e n t s l i m i t i n t a k e when 55 to 60% of the c e l l dry matter i s made up of f i b r e c o n s t i t u e n t s . In a general way, then, as the f i b r e component of a p l a n t i n c r e a s e s , i n t a k e decreases. Lignen shows the poorest and c e l l w a l l c o n s t i t u e n t s the best r e l a t i o n s h i p w i t h i n t a k e (Van Soest, 1965) even though l i g n i n was h i g h l y c o r r e l a t e d w i t h a l l f i b r o u s p l a n t components. This was because t o t a l f i b r e was not n e c e s s a r i l y c l o s e l y r e l a t e d w i t h the l e v e l of l i g n i n i n a forage and does not n e c e s s a r i l y increase uniformly as the forage matures. This was the case w i t h a l f a l f a which has a higher l i g n i n content than grasses but i s g e n e r a l l y consumed i n greater amounts. In grasses, l i g n i n tends to i n c r e a s e more or l e s s l i n e a r l y w h i l e c e l l w a l l c o n s t i t u e n t s tend to increase r a p i d l y e a r l y i n the season and then l e v e l o f f . M e i j s (1981) i n d i c a t e d that i n d a i r y cow r a t i o n s there was no r e l a t i o n s h i p between crude p r o t e i n or crude f a t content of the feed and feed i n t a k e by the cows. However, when the crude p r o t e i n content of the feed f a l l s below 6-8%, i n t a k e drops, apparently due to a d e f i c i e n c y of c i r c u l a t i n g amino acid s ( B a i l e and Forbes, 1974). Lipke (1980) found that p r o t e i n was s i g n i f i c a n t l y r e l a t e d to i n t a k e but could not e s t a b l i s h a b i o l o g i c a l b a s i s s i n c e the supplementation of a d d i t i o n a l p r o t e i n to forages w i t h l e s s than 6% crude p r o t e i n d i d not a p p r e c i a b l y increase i n t a k e or d i g e s t i b i l i t y . Minson (1982) i n d i c a t e d that a number of r e g r e s s i o n equations have been formulated and, although they are s i g n i f i c a n t , chemical composition f a i l s to account f o r a l l of the d i f f e r e n c e s i n i n t a k e between samples. Most of the v a r i a t i o n was caused by true d i f f e r e n c e s i n i n t a k e of p l a n t species of the same chemical composition. The i n t e r r e l a t i o n s h i p s between in t a k e and chemical composition are h i g h l y s p e c i e s - o r i e n t e d (Van Soest, 1965) . In a d d i t i o n , d i f f e r e n c e s i n i n t a k e between l e a f and stem f r a c t i o n s occur w i t h the i n t a k e of l e a f considerably higher than stems of s i m i l a r chemical composition. Van Soest (1965) i n d i c a t e d that chemical composition was g e n e r a l l y more c l o s e l y r e l a t e d to d i g e s t i b i l i t y than i n t a k e due to the c o r r e l a t i o n of c e l l w a l l c o n s t i t u e n t s ( f i b r o u s m a t e r i a l ) w i t h d i g e s t i b i l i t y , e s p e c i a l l y w i t h i n species (Osbourn, 1978). 2.1.3.4 LEAF AND STEM Laredo and Minson (1973) reported that the v o l u n t a r y i n t a k e of l e a f was always higher than that of the stem f r a c t i o n at the same d i g e s t i b i l i t y although the l e v e l s v a r i e d between d i f f e r e n t species and the m a t u r i t y of regrowth. The d i f f e r e n c e i n i n t a k e between l e a f and stem f r a c t i o n s i n 30 comparisons was 42% lower f o r stems than leaves w i t h a d i f f e r e n c e of only 1% i n d i g e s t i b i l i t y of the two f r a c t i o n s (Minson, 1982). This may be the r e s u l t of the l e a f p o r t i o n being r e t a i n e d f o r a s h o r t e r p e r i o d of time i n the rumen than the stem p o r t i o n which allowed more feed to be consumed (Laredo and Minson, 1973; Poppi et a l . , 1980). Minson (1982) suggested that the l a r g e r r e t e n t i o n time of the stem f r a c t i o n i n the rumen was due to the higher p r o p o r t i o n of l a r g e p a r t i c l e s i n the masticated stem than i n masticated l e a f because the stem shows greater r e s i s t a n c e to p h y s i c a l breakdown. These l a r g e p a r t i c l e s of the stem w i l l remain longer i n the rumen than the l a r g e p a r t i c l e s of the l e a f f r a c t i o n . 2.1.3.5 CHOPPING AND PELLETING The i n t a k e of a forage was u s u a l l y increased when i t was ground and p e l l e t e d as compared to long hay (Minson, 1982). The d i f f e r e n c e i n i n t a k e was a s s o c i a t e d w i t h a f a s t e r r a t e of passage through the rumen but chopping per se would not increase i n t a k e over long hay u n t i l a c e r t a i n p a r t i c l e s i z e (between 4 and 8 mm) was reached (Robles et a l . , 1980). Weston and Hogan (1967) i n d i c a t e d that ground a l f a l f a hay consumption was 41% higher than chopped a l f a l f a hay and ground wheat straw consumption was 31% higher than chopped wheat straw. The authors concluded that the increased v o l u n t a r y i n t a k e caused by g r i n d i n g and p e l l e t i n g was not accompanied by any s i g n i f i c a n t changes i n the chemical composition of the d i e t . 2.2 FACTORS AFFECTING FEED DIGESTIBILITY Schneider and F l a t t (1975) define d i g e s t i b i l i t y "as the percentage of the feed or of any s i n g l e n u t r i e n t of the feed which was d i s s o l v e d or otherwise acted upon i n the e n t i r e d i g e s t i v e t r a c t so i t can be absorbed and thus put at the d i s p o s a l of the body c e l l s " . There are s e v e r a l animal and p l a n t r e l a t e d f a c t o r s that a f f e c t d i g e s t i b i l i t y of f e e d s t u f f s which are discussed i n t h i s s e c t i o n . 2.2.1 ANIMAL FACTORS AFFECTING DIGESTIBILITY B l a x t e r and Wainman (1961) reported t h a t , i n c a t t l e , the animals which consumed the most feed digested i t l e a s t e f f i c i e n t l y . U l y a t t et a l . , (1967) obtained r e s u l t s that showed a s i g n i f i c a n t decrease i n feed d i g e s t i b i l i t y i n the rumen but a s i g n i f i c a n t increase i n d i g e s t i b i l i t y i n the lower alimentary t r a c t , as feed i n t a k e was increased. The authors suggest that w i t h increased feed i n t a k e , the r a t e of passage increased reducing r e t e n t i o n time i n the rumen and t h e r e f o r e d i g e s t i b i l i t y , although there was a compensatory e f f e c t d i s t a l to the rumen. Van Soest (1982) summarized the r e l a t i o n s h i p between i n t a k e and d i g e s t i b i l i t y by i n d i c a t i n g that d i g e s t i b i l i t y depression was a f u n c t i o n of the competition between d i g e s t i o n and the r a t e of passage. The slowest d i g e s t i n g f r a c t i o n s of the c e l l w a l l — c e l l u l o s e and h e m i c e l l u l o s e — are the most a f f e c t e d . Measurements of the r a t e of passage of an average forage i n d i c a t e that c e l l w a l l c o n s t i t u e n t s are r e t a i n e d f o r 40 to 60 hours. Doubling the feed i n t a k e w i l l decrease the r e t e n t i o n time to about 30 to 33 hours i n sheep. Van Soest (1982) concluded that those c e l l w a l l c o n s t i t u e n t s s u s c e p t i b l e to the g r e a t e s t d i g e s t i b i l i t y depression are those that show a s u b s t a n t i a l increase i n d i g e s t i b i l i t y between 30 and 48 hours of fermentation. As a r e s u l t , increased feed i n t a k e r e s u l t s i n reduced feed d i g e s t i b i l i t y i n most cases. 2.2.2 PLANT FACTORS AFFECTING DIGESTIBILITY Seve r a l p l a n t f a c t o r s a f f e c t d i g e s t i b i l i t y i n c l u d i n g forage type, species and v a r i e t y ; maturity and c u t t i n g date; p r o p o r t i o n of l e a f and stem; chopping and p e l l e t i n g ; and the e f e c t s of chemical treatments. 2.2.2.1 FORAGE TYPE, SPECIES AND VARIETY Even though DMI was h i g h e r , DMD of legumes was g e n e r a l l y lower or only equal to that of grasses harvested at s i m i l a r periods of the growing season (Troelson and Campbell, 1969; Thornton and Minson, 1973). The lower DMD of legumes compared w i t h grasses was due to a number of f a c t o r s . Legumes tend to have a higher c e l l w a l l content (and l e s s c e l l s o l u b l e m a t e r i a l ) than grasses (Osbourne et_ a l . , 1974). Even though t h i s was the case, the p r o p o r t i o n of digested c e l l w a l l m a t e r i a l i s about the same (Moir, 1972). Mosley and Jones (1984) and Beever et a l . (1985) found that c l o v e r had lower l e v e l of s o l u b l e carbohydrates, comparable c e l l u l o s e and higher N l e v e l s than grasses and that i n c l o v e r d i e t s , p r o p o r t i o n a t e l y l e s s of the ingested organic matter appeared to be digested i n the rumen. Thornton and Minson (1973) found that legumes were r e t a i n e d f o r a s h o r t e r p e r i o d i n the rumen w i t h a g r e a t e r percentage of white c l o v e r p a r t i c u l a t e matter than of ryegrass disappearing i n the f i r s t 3 hours a f t e r consumption (Moseley and Jones, 1984). Both Minson £t a l . (1964) and Troelson and Campbell (1969) found 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 between grass species depending on the stage of growth w i t h the second authors r e p o r t i n g increased v a r i a b i l i t y i n DMD as growth progresses. The f i r s t authors concluded i t was not g e n e r a l l y v a l i d to compare the d i f f e r e n t species at defined stages of growth but r a t h e r that data must be i n t e r p r e t e d i n c o n j u n c t i o n w i t h y i e l d and season of p r oduction. D i g e s t i b i l i t y of the regrowth of any species was much l e s s v a r i a b l e than the d i g e s t i b i l i t i e s of the f i r s t growths (Minson et^ a l _ . , 1964) . M i l f o r d and Minson (1966) found that orchardgrass was l e s s d i g e s t i b l e than ryegrass at a l l growth stages r e f l e c t i n g the lower s o l u b l e carbohydrate content of the orchardgrass. Lower s o l u b l e carbohydrate l e v e l s would i n d i c a t e increased f i b r e l e v e l s and Burns et a l . (1985) found that i n the higher q u a l i t y forages s t u d i e d , d i g e s t i b i l i t y of other f i b r e c o n s t i t u e n t s were a l s o higher. The poorly digested grasses showed lower d i g e s t i o n c o e f f i c i e n t s f o r h e m i c e l l u l o s e , c e l l u l o s e and c e l l w a l l c o n s t i t u e n t s . D i f f e r e n c e s i n DMD between v a r i e t i e s have been reported i n grasses at s i m i l a r growth stages or percentage of l e a f (Walters, 1971). In another study the v a r i e t y i n another study w i t h the highest d i g e s t i b i l i t y a l s o had the highest p r o p o r t i o n of s o l u b l e carbohydrates while the v a r i e t y w i t h the lower d i g e s t i b i l i t y had the lowest l e v e l s of s o l u b l e carbohydrates (Bland and Dent, 1964). 2.2.2.2 PLANT MATURITY AND DATE OF CUTTING I t was g e n e r a l l y accepted that DMD d e c l i n e s w i t h advancing forage growth through the growing season (Troelson and Campbell, 1969; White and Wight, 1981). However, there can be some exceptions to the general case. For example, H i d i r o g l o u et a l . (1966) reported that timothy showed no apparent d e c l i n e i n d i g e s t i b i l i t y from mid-August through mid-October and Troelson and Campbell (1969) i n d i c a t e d that l a t e r i n the season a l f a l f a s d i d not d e c l i n e i n n u t r i t i o n a l v a l u e . C u t t i n g r e t a r d s growth but the e f f e c t s are not always p r e d i c t a b l e because f a c t o r s other than the stage of growth (such as environmental e f f e c t s ) must be considered (Van Soest, 1982). However, both H i d i r o g l o u et a l . (1966) and Minson et a l . (1964) i n d i c a t e d that regrowth i n grasses was l e s s d i g e s t i b l e than f i r s t growth. Wilman and A t l i m i m i (1982) i n d i c a t e d that i n ryegrass, the stem p o r t i o n of the pla n t d e c l i n e d i n d i g e s t i b i l i t y w i t h advancing m a t u r i t y f a s t e r than the l e a f blade. The d i g e s t i b l e energy content i n the stems d e c l i n e d at more than twice the r a t e of the d e c l i n e i n the leaves (Hacker and Minson, 1981). In a d d i t i o n , dry matter, crude p r o t e i n , s o l u b l e sugars and c e l l u l o s e were more d i g e s t i b l e i n a l f a l f a leaves than a l f a l f a stems w h i l e crude f i b r e was more d i g e s t i b l e i n the stems. Reasons f o r the d e c l i n e i n DMD have been suggested by Troelson and Campbell (1969) and K i l c h e r and Troelson (1973). Crude p r o t e i n l e v e l s d e c l i n e d w i t h advancing maturity i n both the leaves and stems of a l f a l f a and bromegrass w h i l e crude f i b r e l e v e l s increased i n both leaves and stems. C e l l w a l l l i g n i n increased at a slower r a t e i n the leaves than i n the stems as the p l a n t s matured. The depressing e f f e c t of crude f i b r e on d i g e s t i b i l i t y was due to the presence of l i g n i n which p r o t e c t s some of the c e l l u l o s e and h e m i c e l l u l o s e of the c e l l w a l l from m i c r o b i a l d i g e s t i o n (Hacker and Minson, 1981). 2.2.2.3 LEAF AND STEM Van Soest (1982) s t a t e d t h a t , i n g e n e r a l , stems are u s u a l l y of lower q u a l i t y than leaves. In I t a l i a n and p e r e n n i a l ryegrass harvested at s i m i l a r stages of m a t u r i t y , the l e a f component of the p l a n t had a higher DMD than the stem component, which was c o n s i s t e n t w i t h a higher d i g e s t i b i l i t y of the c e l l w a l l c o n s t i t u e n t s (Wilman and A l t i m i m i , 1982). 2.2.2.4 CHOPPING AND PELLETING I t was g e n e r a l l y recognized that dry matter d i g e s t i b i l i t y was reduced when feeds are ground and p e l l e t e d (Greenhalgh and Reid, 1973; Van Soest, 1982). The response d i f f e r s between forage s p e c i e s , i n part due to the greater depression of organic matter d i g e s t i b i l i t y induced by m i l l i n g the grasses compared w i t h the legumes (Osbourne et al^. , 1981). Weston and Hogan (1967) i n d i c a t e d that at ad_ l i b i t u m l e v e l s of feeding the r a t e of flow from the abomasum was 20-301 higher w i t h ground hay than w i t h chopped hay. Robles et a l . (1980) found that orchardgrass and a l f a l f a would have to be ground through screens smaller than 8 mm before a r e d u c t i o n i n d i g e s t i b i l i t y would be expected. Chopped forages p a r t i c l e s are longer than 8 mm and thus would not e x h i b i t the same d i g e s t i b i l i t y depression. B l a x t e r and Graham (1956) found that the maximum depression i n d i g e s t i b i l i t y of f i n e l y ground grass m a t e r i a l occurred i n the c e l l w a l l c o n s t i t u e n t s . This was expected s i n c e the fermentation of s t r u c t u r a l carbohydrates was slow and, sin c e f i n e l y ground m a t e r i a l s have a lower r e t e n t i o n time i n the rumen, the r a p i d passage of food through the d i g e s t i v e t r a c t would r e s u l t i n reduced d i g e s t i b i l i t y of the f i b r o u s components of the c e l l w a l l . The e f f e c t of p e l l e t i n g mature forages on d i g e s t i b i l i t y may be l i m i t e d because the l i g n i f i e d c e l l w a l l s c o l l a p s e l e s s on p e l l e t i n g than the l e s s l i g n i f i e d younger forages and the i n t a k e of d i g e s t i b l e n u t r i e n t s may remain low (Van Soest, 1982). 2.2.2.5 CHEMICAL TREATMENTS Chemical treatments (urea, ammonia or NaOH) s i g n i f i c a n t l y increased the d i g e s t i b i l i t y of poor q u a l i t y feeds (Wanapet est a l . , 1985) . Sundstol (1984) a l s o r e p o r t s that the inta k e of straw was increased when t r e a t e d w i t h ammonia. Crude f i b r e d i g e s t i b i l i t y was s u b s t a n t i a l l y increased (10 to 20 percentage u n i t s ) due, the authors f e e l , to the s o l u b i l i z a t i o n of h e m i c e l l u l o s e i n c r e a s i n g the r a t e and extent of c e l l u l o s e and h e m i c e l l u l o s e d i g e s t i o n . N balances were improved by treatment w i t h urea and anhydrous ammonia but NaOH treatment r e s u l t e d i n higher o v e r a l l d i g e s t i b i l i t i e s . 2.3 ENVIRONMENTAL FACTORS AFFECTING INTAKE AND DIGESTIBILITY Van Soest et a l . (1978) reported that environmental temperature, which increases l i g n i n , was the dominant environmental f a c t o r e f f e c t i n g d i g e s t i b i l i t y w h i l e the other e f f e c t s (temperature, water, f r o s t , l i g h t , season and daylength) are secondary. The e f f e c t s of temperature on DMD i n d i c a t e that the d i g e s t i b i l i t y of temperate forages grown i n warm areas can be a f f e c t e d i n a manner s i m i l a r to t r o p i c a l forages and increased temperatures can r e s u l t i n decreased DMD and increased p r o p o r t i o n s of c e l l w a l l c o n s t i t u e n t s (Deinum et_ a l . , 1968). High temperatures appear to hasten the normal process of t i s s u e aging and apparently decrease the d i g e s t i b i l i t y of e x i s t i n g c e l l w a l l m a t e r i a l (Wilson et_ a l . , 1976) . Wilson and Ng (1975) concluded that water s t r e s s c l e a r l y retarded p l a n t development w i t h s t r e s s e d leaves being o n t o g e n e t i c a l l y younger than t h e i r a c t u a l age. a comparison of water s t r e s s e d and unstressed leaves at the same p h y s i o l o g i c a l age r e v e a l s v i r t u a l l y no e f f e c t of s t r e s s on the content of c e l l w a l l m a t e r i a l or n i t r o g e n i n s p e c i f i c p l a n t p a r t s . G e n e r a l l y , any f a c t o r that r e t a r d s p l a n t development tends to maintain q u a l i t y and thus water s t r e s s r e s u l t s i n a more d i g e s t i b l e crop of lower y i e l d (Van Soest, et a l . , 1978). F r o s t r e s u l t s i n a r a p i d d e c l i n e i n the n u t r i t i v e value of grasses w i t h f r o s t k i l l e d leaves d e c l i n i n g r a p i d l y i n DMD and CP. Freezing and more thawing patt e r n s lead to l e a c h i n g and r e s p i r a t i o n l o s s e s of the more d i g e s t i b l e p l a n t c o n s t i t u e n t s (Wilson, 1982) by degrading the components of the t r a n s l o c a t i o n path system and u l t i m a t e l y a f f e c t i n g other metabolic processes i n c l u d i n g photosynthesis (Bula and Massengale, 1972). Increased l i g h t i n t e n s i t y increased s o l u b l e carbohydrate and DMD l e v e l s of grasses through the photosynthetic accumulation of carbohydrates (Right et a l _ . , 1968) . L i g h t induced photosynthesis a l s o promoted the re d u c t i o n of n i t r a t e and i t s conversion, w i t h carbohydrates, to amino a c i d s and p r o t e i n . Thus forages grown under cloudy c o n d i t i o n s or i n humid, foggy areas under reduced l i g h t c o n d i t i o n s w i l l be lower i n DMD than forages from a r i d environments (Van Soest et a l . , 1978). The DMD of grasses was higher i n the s p r i n g than f a l l f o r two st u d i e s (White and Wight, 1981; Reid et a l . , 1967). However, H i d i r o g l o u et a l . (1966) obtained higher DMD i n f a l l harvested forage from northern O n t a r i o . The f i r s t r e s u l t was as s o c i a t e d w i t h higher c e l l w a l l c o n s t i t u e n t s and lower s o l u b l e carbohydrates i n the f a l l forage (Reid et a l . , 1967) wh i l e i n the second case, crude f i b r e l e v e l s were lower and crude p r o t e i n l e v e l s higher i n the f a l l than i n the s p r i n g ( H i d i r o g l o u et a l . , 1966). Deinum et^ a l . (1968) i n d i c a t e d that v e g e t a t i v e grass i n high summer time w i l l have a s l i g h t l y higher DMD than i n autumn due to the low l i g h t i n t e n s i t y and s t i l l comparatively high temperatures i n the l a t e r p art of the season. Thus, the e f f e c t of season and daylength upon DMD v a r i e s due to a number of f a c t o r s (Van Soest et a l . , 1978) . The r e l a t i o n s h i p w i t h temperature and daylength v a r i e s w i t h the season, daylength being a p r i n c i p l e f a c t o r i n f l u e n c i n g the amount of l i g h t r e c e i v e d . 2.4 TROPICAL VERSUS TEMPERATE FORAGES The v o l u n t a r y i n t a k e of t r o p i c a l grasses was u s u a l l y l e s s than f o r temperate grasses harvested at the same growth stage (Minson, 1981). This i s a s s o c i a t e d w i t h higher f i b r e l e v e l s i n the t r o p i c a l grasses at a l l stages of growth r e s u l t i n g i n lower dry matter d i g e s t i b i l i t y , l a r g e r q u a n t i t i e s of i n d i g e s t i b l e f i b r e and longer r e t e n t i o n time i n the rumen. However, t r o p i c a l grasses are u s u a l l y consumed i n greater amounts than temperate grasses of the same d i g e s t i b i l i t y . This was because a t r o p i c a l grass at 60% d i g e s t i b i l i t y was young and r e l a t i v e l y l e a f y w h i l e a temperate grass would be stemmy and mature. Norton (1982) pointed out that mesophyll c e l l s i n t r o p i c a l grasses are more densely packed and i n t e r c e l l u l a r a i r spaces lower i n volume than temperate grasses. This r e s t r i c t s the entry of m i c r o b i a l d i g e s t i v e enzymes thereby depressing the r a t e of d i g e s t i o n of the f i b r o u s t i s s u e s of the p l a n t . This would r e s u l t i n longer r e t e n t i o n time and t h e r e f o r e lower intake of t r o p i c a l grasses. The DMD of t r o p i c a l grasses was g e n e r a l l y lower than that of temperate grasses and legumes. Summaries of reported d i g e s t i b i l i t i e s i n d i c a t e that t r o p i c a l forages have d i g e s t i b i l i t i e s of about 15 u n i t s lower than temperate forages (Minson and McLeod, 1970). The lower d i g e s t i b i l i t y appears to be due to higher temperatures at which they are grown and not due to b a s i c d i f f e r e n c e s between them (Minson, 1981). Temperate and t r o p i c a l grasses grown under the same temperature and co n d i t i o n s had s i m i l a r dry matter d i g e s t i b i l i t i e s (Minson and McLeod, 1970) and the authors concluded that 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 of the two c a t e g o r i e s of forages are c l o s e l y a s s o c i a t e d w i t h d i f f e r e n c e s i n c l i m a t e . 2.5 LABORATORY METHODS OF ASSESSING FORAGE VALUE In v i v o techniques f o r es t i m a t i n g n u t r i t i v e value and in t a k e are expensive, time consuming and r e q u i r e l a r g e amounts of forage ( F e r r e i r a and C o l l i n s , 1982). Laboratory a n a l y s i s was g e n e r a l l y l e s s expensive and f a s t e r than animal feeding s t u d i e s and was u s e f u l i n e x p l a i n i n g n u t r i t i o n a l phonomena and f o r d e s c r i b i n g feed c h a r a c t e r i s t i c s u s e f u l i n for m u l a t i n g r a t i o n s (Van Soest, 1982). The major l a b o r a t o r y techniques used f o r e v a l u a t i n g herbage q u a l i t y ' i n c l u d e i n v i t r o dry matter d i g e s t i b i l i t y (IVDMD), chemical (eg. f i b r e ) , and jLn s i t u (Nylon bag dry matter disappearance — NBDMD) techniques. The i n v i v o parameters most o f t e n of i n t e r e s t i n c l u d e d i g e s t i b l e energy (DE), dry matter d i g e s t i b i l i t y (DMD), organic matter d i g e s t i b i l i t y (OMD) and v o l u n t a r y i n t a k e of dry matter (DMI). The p a r t i c u l a r l a b o r a t o r y technique used depends on the i n v i v o parameter to be estimated and must be based upon experimentally determined r e l a t i o n s h i p s w i t h the i n t a c t animal. This s e c t i o n , then w i l l review the commonly used l a b o r a t o r y methods and how they r e l a t e to animal p r o d u c t i v i t y . 2.5.1 PROXIMATE ANALYSIS The Proximate A n a l y s i s system was the ol d e s t method of assessing forage value and most work has t r a d i t i o n a l l y been done using t h i s system. Fonnesbeck (1976) pointed out that the proximate components do not represent the feed f r a c t i o n s they were intended to and crude f i b r e (CF) from one feed was not n e c e s s a r i l y comparable i n composition w i t h t h i s f r a c t i o n i n another feed ( F e r r e i r a and C o l l i n s , 1982). Van Soest (1965) pointed out that o f t e n the l e a s t d i g e s t i b l e p a r t s of f i b r e , x y l a n and l i g n i n , are e x t r a c t e d and inc l u d e d i n the NFE. In a d d i t i o n , most of the h e m i c e l l u l o s e was d i s s o l v e d . As a r e s u l t , CF, which was b e l i e v e d to con t a i n the n o n - d i g e s t i b l e p o r t i o n of the feed, was o f t e n equal to or higher i n d i g e s t i b i l i t y than the NFE ( F e r r e i r a and C o l l i n s , 1982). Crampton and Maynard (1938) long ago concluded that the s p e c i f i c values obtained from proximate a n a l y s i s have o f t e n been over-estimated and t h i s i s e s p e c i a l l y the case f o r the f i b r e f r a c t i o n . They f u r t h e r i n d i c a t e d that any r e l a t i o n CF may have to the d i g e s t i b i l i t y of a feed may be, i n p a r t , f o r t u i t o u s . I n a recent e v a l u a t i o n of l a b o r a t o r y methods f o r p r e d i c t i n g the organic matter d i g e s t i b i l i t y of forages, A e r t s _e_t a l . (1977) determined the r e g r e s s i o n c o e f f i c i e n t of CF f o r e s t i m a t i n g in v i v o OMD of v a r i o u s 2 forages. The r e s u l t s showed CF had an r of 0.35 f o r e s t i m a t i n g i n v i v o OMD i n grass hay, 0.68 f o r s i l a g e s and 0.59 f o r p e l l e t s . These l e v e l s were only s l i g h t l y lower than ADF f o r grass hays (0.41) and p e l l e t s (0.68) and about the same f o r s i l a g e s (0.65). The main c r i t i c i s m w i t h the use of CF to estimate the n u t r i t i v e value of a feed i s v a r i a b l e chemical composition of the residue when compared to those f i b r e components a c t u a l l y digested by the animal. S i m i l a r concerns are expressed about crude p r o t e i n (CP) sin c e forages a l s o c o n t a i n v a r y i n g l e v e l s of n u c l e i c a c i d s , water s o l u b l e non-protein n i t r o g e n and i n s o l u b l e n i t r o g e n found i n a s s o c i a t i o n w i t h l i g n i n (Van Soest, 1967). Schneider and F l a t t (1975) a l s o i n d i c a t e d that the ash f r a c t i o n gives no i n d i c a t i o n of the a c t u a l m i n e r a l content of the feed, nor does the proximate a n a l y s i s system evaluate v i t a m i n l e v e l s . Both types of n u t r i e n t s are a concern because an inadequate supply of even an e s s e n t i a l m i n e r a l or v i t a m i n may r e s u l t i n production problems. The proximate a n a l y s i s system has continued i n use due to a conservative tendency to continue to r e l y on e s t a b l i s h e d procedures d e s p i t e obvious l i m i t a t i o n s and inadequate understanding of the meaning and purpose of f i b r e determinations (Van Soest, 1967). 2.5.2 IN VITRO DRY MATTER DISAPPEARANCE While there are many i n v i t r o dry matter disappearance (IVDMD) techniques, most are m o d i f i c a t i o n s of the T i l l e y and Terry (1963) technique (Rode and S a t t e r , 1984). T i l l e y and Terry (1963) e x p l a i n that w h i l e i n v i v o d i g e s t i b i l i t y experiments a i d i n es t i m a t i n g forage n u t r i t i v e value f o r ruminants such experiments are time consuming and re q u i r e l a r g e amounts of feed. The c o r r e l a t i o n s between i n v i v o herbage d i g e s t i b i l i t y and the contents of i n d i v i d u a l chemical components such as CF, CP and l i g n i n are l i m i t e d and cannot be a p p l i e d e q u a l l y to a l l forage p l a n t s . As a r e s u l t , i n v i v o d i g e s t i b i l i t y and chemical techniques are not a v a i l a b l e to p l a n t breeders f o r such purposes as the i n i t i a l s e l e c t i o n of new v a r i e t i e s . F e r r e i r a and C o l l i n s (1982) concluded that the IVDMD technique has ge n e r a l l y been reported s u p e r i o r to other l a b o r a t o r y methods f o r p r e d i c t i n g i n v i v o DMD. The technique has been misused due to attempts to estimate DMI from IVDMD v a l u e s , something the process was not designed f o r . The technique was most u s e f u l f o r determining the r e l a t i v e d i f f e r e n c e s between forage samples r a t h e r than as a means of es t i m a t i n g i n v i v o d i g e s t i b i l i t y due to the numerous f a c t o r s a f f e c t i n g d i g e s t i b i l i t y ( F e r r e i r a and C o l l i n s , 1982). Van Soest (1982) has suggested that the main disadvantage w i t h the IVDMD technique was the length of time and number of steps r e q u i r e d to ca r r y out the procedure. Another major disadvantage was the v a r i a t i o n i n innoculum. The donor animal, method of sampling and processing the innoculum, and the amount of innoculum a l l a f f e c t the r e s u l t . V a r i a t i o n between animal s p e c i e s , i n d i v i d u a l s , or the same animal between days have a l s o been noted (Barnes, 1973). 2.5.3 NYLON BAG DRY MATTER DISAPPEARANCE The nylon bag dry matter disappearance (NBDMD) technique ( a l s o r e f e r r e d to as the i n s i t u or i n sacco technique) was u s e f u l f o r measuring the r a t e and p o t e n t i a l extent of d i g e s t i o n of feeds and the e f f e c t s of v a r i o u s r a t i o n treatments such as supplementation, on these parameters (Barnes, 1973). The technique provides a simple and inexpensive method of assessing forage q u a l i t y (Playne et_ a_l., 1978) and has been used to examine the disappearance of DM, f i b r e and CP (Rode and S a t t e r , 1984). The main advantages of the technique was p l a c i n g the f e e d s t u f f i n the a c t u a l animal as opposed to s i m u l a t i n g ruminal a c t i v i t y i n v i t r o . In a comparison of s e v e r a l d i f f e r e n t methods of es t i m a t i n g OMD Aerts et a l . , (1977) found that the NBDMD technique (48 hours i n s i t u f o l l owed 2 by a 48 hour pepsin incubation) r e s u l t e d i n an r of 0.92. This was the highest r e l a t i o n s h i p of any of the other techniques, i n c l u d i n g the IVDMD and chemical parameters, examined. However, Barnes (1973) reported that the technique was subject to considerable v a r i a t i o n and was d i f f i c u l t to s t a n d a r d i z e . Sources of v a r i a t i o n i n c l u d e s i z e and type of bags, c l o t h mesh s i z e , sample s i z e , f i neness of g r i n d , number of samples per t r i a l , d i e t of the host animal, i n d i v i d u a l i t y of host animal, method of suspension i n the rumen, l o c a t i o n and time i n the rumen, methods of c l e a n i n g and r i n s i n g incubated bags, and i n c l u s i o n or e x c l u s i o n of a second stage pepsin d i g e s t i o n step. S e v e r a l authors have examined the importance of bag pore s i z e on subsequent DM disappearance. The three main c o n s i d e r a t i o n s are l e a c h i n g of undegraded m a t e r i a l s from the bags, e x c l u s i o n of rumen b a c t e r i a from the s u b s t r a t e w i t h i n the bag and accumulation of exogenous m a t e r i a l w i t h - i n the bag (Van H e l l e n and E l l i s , 1977; Mehrez and Orskov, 1977). Playne et a l . (1978) i n d i c a t e d that DM l o s s e s due to l e a c h i n g could be s e r i o u s and a c o r r e c t i o n f a c t o r should be used to account f o r such l o s s e s . Playne et a l . (1978) i n d i c a t e d that sample s i z e had l i t t l e e f f e c t on DMD as long as sample s i z e to bag s i z e r a t i o was h e l d constant; however, Nocek (1985) found that clumping of the substrate i n the bag increased as sample weight increased. Fineness of the g r i n d of the substrate a l s o a f f e c t s DMD w i t h l o s s e s from the bag being greater f o r the 1 mm than the 2 mm m i l l i n g s i z e (Playne et a l . 1978). Clumping of feed substrates w i t h i n the bag was noted f o r the 1 mm s i z e g r i n d . Weakley et^ a l . (1983) found the greatest d i f f e r e n c e i n DMD between feeds of d i f f e r e n t p a r t i c l e s i z e occurred i n the f i r s t few hours and the o v e r a l l d i f f e r e n c e s were not as large as might be expected. There was some i n d i c a t i o n that the i n d i v i d u a l animal a f f e c t s NBDMD. Nocek (1985) reported that h i s data suggested v a r i a t i o n w i t h i n animals i n ruminal fermentation patterns and that the i n c l u s i o n of a standard feed may be necessary to monitor the v a r i a t i o n . Mehrez and Orskov (1977) found that the great e s t source of v a r i a t i o n i n t h e i r study was that due to t e s t animal followed by day of t e s t . The l e a s t d i f f e r e n c e occured between t e s t bags. Weakley e£ a l . (1983) d i d not observe any s i g n i f i c a n t d i f f e r e n c e s among cows and i n d i c a t e d there may be no need to be concerned w i t h the animal e f f e c t s on NBDMD i n substrates s i m i l a r to soybean meal. However, these authors d i d f i n d a s i g n i f i c a n t d i f f e r e n c e due to animal d i e t w i t h DM disappearance being lower f o r those animals being fed a high concentrate r a t i o n and speculate that t h i s may be due to b a c t e r i a l slime s e a l i n g the pores and b l o c k i n g the i n f l u x of d i g e s t i v e organisms. Lindberg (1981a, 1981b) a l s o found s i g n i f i c a n t d i f f e r e n c e s i n NBDMD due to b a s a l d i e t s although there was some v a r i a b i l i t y depending on the substrate being examined. For example, bags c o n t a i n i n g hay and sugar beet pulp decreased i n DMD when the amount of roughage of the b a s a l d i e t decreased w h i l e w i t h f i s h meal there was a tendency towards i n c r e a s i n g DMD. Straw and gr a i n s showed no s i g n i f i c a n t d i f f e r e n c e between b a s a l d i e t s . Lindberg (1981b) r e l a t e d t h i s to changes i n rumen a c t i v i t y as the m i c r o b i a l p o p u l a t i o n s h i f t s from f i b r e d i g e s t i n g to amyloytic and s a c c h a r o l y t i c organisms. Rode and Sa t t e r (1984) concluded that to reduce v a r i a b i l i t y i t was best to use animals e a t i n g a r a t i o n s i m i l a r to the feeds being evaluated. Mehrez and Orskov (1977) reported that i n c r e a s i n g the time of i n c u b a t i o n from 7 to 24 hours d i d not s u b s t a n t i a l l y reduce v a r i a b i l i t y . Nocek (1985) i n d i c a t e d that the method of i n t r o d u c i n g and removing the bags i n a time s e r i e s a f f e c t e d disappearance. Bags were e i t h e r introduced at s p e c i f i c i n t e r v a l s and a l l removed at once or a l l i n s e r t e d at once and removed at s p e c i f i c i n t e r v a l s . When bags were i n s e r t e d at s p e c i f i c i n t e r v a l s and a l l removed at once there was a s l i g h t l y f a s t e r r a t e constant and a s l i g h t l y lower v a r i a t i o n s i n r e s u l t s . There may be d i f f e r e n c e s i n r e s u l t s due to d i f f e r e n c e s i n washing technique (Weakley et_ a l . , 1983). Washing caused the l o s s of p o t e n t i a l l y degradeable water s o l u b l e components of the sub s t r a t e ( H o v e l l et a l . , 1986). However, i f the degradation c h a r a c t e r i s t i c s were s i m i l a r to the m a t e r i a l l e f t i n the bags the c o r r e c t i o n would be s m a l l . Weakley et a l . (1983) i n d i c a t e d that most authors have found l i t t l e d i f f e r e n c e i n washing l o s s e s between days. De F a r i a and Huber (1984) , i n comparing NBDMD and IVDMD r e s u l t s found that the two methods c o n s i s t e n t l y ranked the forages being s t u d i e d i n the same order but the NBDMD technique y i e l d e d higher percentage l e v e l s of disappearance. There was high c o r r e l a t i o n between the two techniques when the bags were removed at 48 and 72 hours but only a low c o r r e l a t i o n when the bags were removed at 24 hours. Therefore, a poor q u a l i t y hay would have to be r e t a i n e d 3 times as long i n s i t u as the other b e t t e r q u a l i t y hays to o b t a i n r e s u l t s s i m i l a r to those obtained i n v i v o . This emphasizes the d i f f i c u l t y i n r e l a t i n g degradation measurements made w i t h a f i x e d time p e r i o d to apparent i n v i v o d i g e s t i b i l i t y . Lindberg (1982c) found the degradation r a t e measured w i t h nylon bags was an over-estimate of a c t u a l degradation at any given time since the feed p a r t i c l e s are prevented from l e a v i n g the rumen. This i m p l i e s that the degradation c h a r a c t e r i s t i c s of d i f f e r e n t feeds could be of greater n u t r i t i o n a l s i g n i f i c a n c e than the d i l u t i o n r a t e from the rumen because the i n d i v i d u a l degradation r a t e w i l l a f f e c t d i l u t i o n r a t e . 2.5.4 CHEMICAL SYSTEMS The o b j e c t i v e of l a b o r a t o r y analyses was to determine the composition of a feed from which an estimate of animal response w i l l be made. Since the n u t r i t i v e value of a forage was a f f e c t e d by composition, the problem of p r a c t i c a l e v a l u a t i o n through chemical a n a l y s i s was dependent upon the understanding of the fundamental p h y s i c a l and chemical f a c t o r s c o n t r o l l i n g the a v a i l a b i l i t y of n u t r i e n t s . There was no such t h i n g as a best method because the n u t r i t i v e aspects of q u a l i t y are complex and there was no chemical method that w i l l i s o l a t e the i n d i g e s t i b l e f r a c t i o n of the feed (Van Soest and Robertson, 1980) C e l l contents are e s s e n t i a l l y completely a v a i l a b l e to the animal w h i l e the u n a v a i l a b l e components of a feed are found w i t h i n the c e l l w a l l . The problem, t h e r e f o r e , was determining the p o r t i o n of s t r u c t u r a l carbohydrate that was u n a v a i l a b l e . An adequate system of a n a l y s i s must not only meet s c i e n t i f i c c r i t e r i a but must a l s o be easy to complete and economical so as to be competitive w i t h the proximate a n a l y s i s system. I t must a l s o r e f l e c t those f a c t o r s a f f e c t i n g feed v a r i a t i o n s i n c e v a r i a t i o n due to an unassayed f a c t o r w i l l r e s u l t i n an u n s a t i s f a c t o r y estimate of animal response (Van Soest and Robertson, 1980). Since chemical a n a l y s i s was g e n e r a l l y l e s s expensive and f a s t e r than animal s t u d i e s the use of these techniques i n assessing feed value was i n d i s p e n s i b l e (Van Soest, 1982). 2.5.4.1 VAN SOEST FIBRE SYSTEM Due to general d i s s a t i s f a c t i o n w i t h the Weende (proximate a n a l y s i s ) system, and the CF a n a l y s i s technique and NFE c a l c u l a t i o n i n p a r t i c u l a r , Van Soest (1967) pointed out the need f o r new chemical a n a l y s i s techniques. There has been a conservative tendency to r e l y on e s t a b l i s h e d procedures des p i t e obvious l i m i t a t i o n s and the CF method s t i l l remains i n use even though problems have been long recognized (Crampton and Maynard, 1938). To overcome the problems of the CF technique ( g e l a t i n i z a t i o n and l o s s of l i g n i n i n the f i l t r a t e when u s i n g sodium hydroxide i n the CF determination to remove nitrogenous consistuents) a method using detergents was proposed (Van Soest, 1963a). I t was intended to overcome the problems w i t h the CF technique and those of e a r l i e r detergent techniques which l e f t a l a r g e p o r t i o n of the p l a n t p r o t e i n undissolved r e s u l t i n g i n an i n a c c u r a t e e s t i m a t i o n of the f i b r e f r a c t i o n . A n i o n i c detergents f a c i l i t a t e the s o l u t i o n of p r o t e i n s i n s l i g h t l y a l k a l i n e c o n d i t i o n s and quaternary ammonium compounds d i s s o l v e p o l y s a c h a r i d e s , p r o t e i n s and n u c l e i c a c i d s r e s u l t i n g i n the p r e p a r a t i o n of f i b r e residues w i t h low N contents i n feed. The use of a detergent i n place of NaOH under mi l d e r c o n d i t i o n s than those of the CF technique may, i n a d d i t i o n , help preserve the i n t e g r i t y of the l i g n i n f r a c t i o n . The o b j e c t i v e of the detergent a n a l y s i s system was the f r a c t i o n a t i o n of forages i n t o n u t r i t i o n a l l y a v a i l a b l e and n u t r i t i o n a l l y u n a v a i l a b l e f r a c t i o n s . The i n d i g e s t i b l e p o r t i o n of the feed was recovered i n the n e u t r a l detergent (ND) residue w h i l e the a c i d detergent (AD) step d i v i d e s the f i b r e i n t o those f r a c t i o n s that are s o l u b l e and i n s o l u b l e i n a 1 N a c i d . The a c i d s o l u b l e s i n c l u d e h e m i c e l l u l o s e and c e l l w a l l p r o t e i n w h i l e the i n s o l u b l e s i n c l u d e c e l l u l o s e and the l e a s t d i g e s t i b l e non-carbohydrate f r a c t i o n s i n c l u d i n g l i g n i n . AD f i b r e (ADF) was a l s o u s e f u l as an i n i t i a l step f o r the s e q u e n t i a l e s t i m a t i o n of l i g n i n , c u t i n , c e l l u l o s e , i n d i g e s t i b l e n i t r o g e n and s i l i c a (Van Soest and Robertson, 1980). N e u t r a l detergent f i b r e (NDF) estimates the p l a n t c e l l w a l l making i t a u s e f u l t o o l f o r e s t i m a t i n g feed i n t a k e . I t gives a poor estimate of d i g e s t i b i l i t y s i n c e p l a n t c e l l w a l l s vary i n d i g e s t i b i l i t y due to d i f f e r e n t f i b r e c o n s t i t u e n t s . Thus, the major problem w i t h any p r e d i c t i o n of d i g e s t i b i l i t y i s that of e s t i m a t i n g the d i g e s t i b i l i t y of c e l l w a l l c o n s t i t u e n t s (Van Soest and Robertson, 1980). ADF was used as a quick method of determining f i b r e i n feeds and was used i n a s i m i l a r manner to CF i n the proximate a n a l y s i s system. The use of the ADF to p r e d i c t d i g e s t i b i l i t y was not founded on any t h e o r e t i c a l b a s i s other than s t a t i s t i c a l a s s o c i a t i o n . Heat damanged p r o t e i n s are a l s o recovered In the f i b r e , s p e c i f i c a l l y the l i g n i n f r a c t i o n s . Van Soest (1963b) reported that the c o r r e l a t i o n of ADF w i t h d i g e s t i b i l i t y f o r 18 forages showed i t to be "somewhat s u p e r i o r " to crude f i b r e (r = -0.79 f o r ADF and r = -0.73 CF r e s p e c t i v e l y ) i n e s t i m a t i n g n u t r i t i o n a l value and was u s e f u l i n e s t i m a t i n g forage d i g e s t i b i l i t i e s f o r r a t i o n f o r m u l a t i o n s . Since NDF i s o l a t e s the slowly d i g e s t i n g components and measures the ND s o l u b l e s ( c e l l contents) Mertens (1983) suggested t h i s a n a l y s i s may be a method of choice f o r e s t i m a t i n g d i g e s t i b i l i t y from a t h e o r e t i c a l p e r s p e c t i v e . NDF was r e l a t e d to i n t a k e and was a p o t e n t i a l l y important component i n r a t i o n f o r m u l a t i o n s . This was the r e s u l t of NDF being r e l a t e d to the bulk d e n s i t y of feeds and the p a r t i c l e s i z e r e d u c t i o n that must occur before feed can escape from the rumen. These f a c t o r s are of g r e a t e s t importance when the p h y s i c a l l i m i t s of the d i g e s t i v e t r a c t r e g u l a t e i n t a k e when intake l e v e l decreases and NDF l e v e l i n c r e a s e s . Thus NDF was u s e f u l f o r e s t i m a t i n g i n t a k e s f o r r a t i o n f o r m u l a t i o n s . Since Van Soest's i n i t i a l paper on the detergent system s e v e r a l problems w i t h the ADF and NDF techniques have been i d e n t i f i e d . Van Soest and Robertson (1980) note three areas r e v o l v i n g around f i l t e r i n g problems. The f i r s t i n v o l v e s the f i l t e r i n g of l i p i d s , which at l e v e l s greater than 10% can r e s u l t due to inadequate l e v e l s of detergent i n the water phase. The second i n v o l v e s p r o t e i n which, when present at l e v e l s greater than 30% exceeds the c a p a c i t y of the detergent to form s o l u b l e complexes. F i n a l l y , s t a r c h may form a v i s c o u s s o l u t i o n i n hot ND s o l u t i o n that can a l s o cause f i l t e r i n g problems. M a t e r i a l s w i t h a high f a t content can a l s o cause problems w i t h the i n i t i a l g r i n d i n g of m a t e r i a l s i n p r e p a r a t i o n f o r the f i b r e a n a l y s i s . There was no d i f f e r e n c e i n NDF l e v e l s based on the volume of ND s o l u t i o n and sample s i z e provided the p r o p o r t i o n s of sample to reagent were the same. There was a d i f f e r e n c e i n NDF l e v e l s when a s i m i l a r sample s i z e was r e f l u x e d i n d i f f e r e n t amounts of ND s o l u t i o n (Mascarenhas F e r r e i r a et a l . , 1983). I n a study of the chemical components of the residues of f i b r e a n a l y s i s system, Colburn and Evans (1967) found that c e l l u l o s e , l i g n i n , CP, and ash accounted f o r 95% of the o r i g i n a l p l a n t c e l l u l o s e and 6% of the CP. S i m i l a r r e s u l t s were obtained by B a i l e y and U l y a t t (1970) who found the ND residues to c o n s i s t of most of the h e m i c e l l u l o s e plus a l l of the c e l l u l o s e . Jorgensen et a l . (1982) found NDF and i n t a k e to be h i g h l y c o r r e l a t e d (r=-0.65 f o r a l f a l f a and r=-0.79 f o r g r a s s e s ) . Rohweder et^ a l . (1978) i n d i c a t e d that ADF was h i g h l y c o r r e l a t e d w i t h i n v i v o DDM (r=-0.83 i n pure legume stands and -0.93 i n grasses) as a r e s u l t of a study of a wide range of temperate and s u b t r o p i c a l grasses and a l f a l f a . They reported the c o r r e l a t i o n between NDF con c e n t r a t i o n and in t a k e ranged from r=-0.32 to -0.94 which v a r i e d w i t h species and l o c a t i o n and was lower i n the s u b t r o p i c a l species compared to the temperate species. In h i s examination of l a b o r a t o r y methods f o r p r e d i c t i n g the OMD of forages A e r t s et a l . (1977) s t a t e d that r e g r e s s i o n s w i t h the separate c e l l w a l l components (NDF, ADF, c e l l u l o s e and l i g n i n ) proved to be i n s u f f i c i e n t l y accurate to estimate OMD. This was a l s o true f o r summative equations based on the c e l l w a l l c o n s t i t u e n t s . A l s o , the estimates of OMD were s i g n f i c a n t l y l e s s accurate w i t h p u r e l y chemical procedures than w i t h methods usi n g l i v i n g micro-organisms i n c l u d i n g NBDMD and IVDMD techniques. Even so, c o e f f i c i e n t s of determination f o r c e l l w a l l c o n s t i t u e n t s , except h e m i c e l l u l o s e and c e l l u l o s e , were greater than those obtained w i t h the Weende system f o r e s t i m a t i n g OMD. In experiments to determine the optimum NDF content of forages f o r m i l k p r o d u c t i o n , Mertens (1983) found no d i f f e r e n c e i n the NDF l e v e l between forages species at maximum m i l k production even though ADF v a r i e d w i d e l y . Mertens concluded that s i n c e NDF was h i g h l y c o r r e l a t e d w i t h i n t a k e , the NDF system probably accounts f o r more v a r i a t i o n i n animal p r o d u c t i v i t y due to the e f f e c t s of forages than other techniques used to formulate r a t i o n s . Jorgensen (1982) supported the use of NDF i n r a t i o n f o r m u l a t i o n by i n d i c a t i n g that the h e m i c e l l u l o s e content of legumes, grasses and by-product feeds v a r i e s g r e a t l y , thus ADF does not adequately represent the t o t a l f i b r e value of f e e d s t u f f s . Hemicellulose was an important p a r t of f i b r e which was overlooked by ADF or CF determinations. They concluded that f i b r e requirements cannot be quoted i n terms of ADF or CF because i t was the t o t a l f i b r e content (NDF) that determines the e f f e c t s . 2.5.4.2 FONNESBECK SYSTEM Fonnesbeck (1976) i n d i c a t e d that most of the chemical methods f o r a n a l y s i s of feed n u t r i e n t s have been adopted on the b a s i s of l a b o r a t o r y p r e c i s i o n and ease of completion without s a t i s f a c t o r y chemical or n u t r i t i o n a l e v a l u a t i o n . More knowledge of p l a n t chemistry, chemical technology and animal n u t r i t i o n a l l o w f o r more comprehensive n u t r i t i o n a l e v a l u a t i o n s . Thus, procedures that a l l o w f o r a more p r e c i s e s e p a r a t i o n of the chemical components of a feed as i t was digested by animals w i l l be more e f f i c i e n t f o r p r e d i c t i n g n u t r i t i v e v a l u e . Since feeds vary g r e a t l y i n t h e i r concentrations of i n d i v i d u a l chemical components, those which i n v o l v e the major d i g e s t i b l e energy sources ( s o l u b l e carbohydrates, p r o t e i n and f a t s ) or the d i l u t i n g compounds ( c e l l u l o s e , h e m i c e l l u l o s e and l i g n i n ) i n t h e i r purest form may more a c c u r a t e l y p r e d i c t the d i g e s t i b l e energy content of feeds i n general. Fonnesbeck (1976) s t a t e d that the n e u t r a l detergent system of Van Soest l e f t 20-50% of the n i t r o g e n remaining w i t h the f i b r o u s t i s s u e w i t h an undetermined amount of s t a r c h a l s o remaining. This detracted from the procedure f o r separating n u t r i t i v e from n o n - n u t r i t i v e components and co n t r i b u t e d to extreme f i l t e r i n g problems when a n a l y s i n g energy feeds, p r o t e i n supplements and mixed d i e t s . Another procedure was r e q u i r e d that w i l l a c c u r a t e l y p a r t i t i o n the feeds i n t o f r a c t i o n s used by animals by a n a l y s i n g f o r carbohydrates as complex components using simple, yet s p e c i f i c , a n a l y s i s when standard substances are not a v a i l a b l e . The Fonnesbeck system (Fonnesbeck and H a r r i s , 1976) separates the p l a n t t i s s u e i n t o c e l l w a l l s and c e l l contents s i m i l a r to the Van Soest procedure. The c e l l w a l l can then be p a r t i t i o n e d i n t o the n u t r i t i v e c e l l w a l l carbohydrates and the n o n - n u t r i t i v e components, l i g n i n and a c i d i n s o l u b l e ash. Van Soest and Robertson (1980) reviewed the system and i n d i c a t e d i t i s not as quick as the Van Soest detergent system but obtained purer f i b r e f r a c t i o n s . They f e e l that the n i t r o g e n removed from the c e l l w a l l s was a s s o c i a t e d w i t h the i n s o l u b l e p r o t e i n that was degraded i n the rumen r e s u l t i n g i n maximal p r o t e i n output and th e r e f o r e was a r e a l e n t i t y . As w e l l , the system does not a l l o w t a n n i n s , c u t i n and M a i l l a r d products to be f r a c t i o n e d out of the crude l i g n i n due to ashing. 2.5.4.3 THE SOUTHGATE SYSTEM The newer f i b r e methods are of l i m i t e d value i n human n u t r i t i o n s i n c e they were developed f o r the ruminant and, as a r e s u l t , Southgate (1976) r e f e r s to d i e t a r y f i b r e as applying to a l l c o n s t i t u e n t s d erived from p l a n t c e l l w a l l s i n the d i e t which are not digested by the endogenous s e c r e t i o n s of the human d i g e s t i v e t r a c t . Since the p l a n t c e l l w a l l carbohydrates are not a v a i l a b l e to man, the f i b r e techniques tend to over estimate the p r o p o r t i o n of c e l l w a l l than can be digested by man. These i n d i g e s t i b l e carbohydrates i n c l u d e p e c t i n , h e m i c e l l u l o s e , c e l l u l o s e and the non-carbohydrate l i g n i n m a t e r i a l (Southgate, 1973). Southgate (1969) i n d i c a t e d the process was t e c h n i c a l l y easy to perform, r e q u i r e s only simple apparatus and takes j u s t over f i v e working days to complete a sample. The polysaccharides are determined using chemical r a t h e r than g r a v i m e t r i c a n a l y s i s and may be f u r t h e r subdivided i n t o w a ter-soluble and i n s o l u b l e s u b f r a c t i o n s . The r e s u l t s i n d i c a t e the method y i e l d s a v i r t u a l l y complete a n a l y s i s of the u n a v a i l a b l e carboyhdrate i n f r a c t i o n s that are important from both a n u t r i t i o n a l and chemical p o i n t of view. Where a l t e r n a t i v e s are a v a i l a b l e to measure a given f r a c t i o n a comparison of the a n a l y t i c a l methods compared w e l l i n a wide v a r i e t y of food s t u f f s . In a c r i t i q u e of the Southgate system, Van Soest and Robertson (1980) i n d i c a t e that the system does not lend i t s e l f to r a p i d a n a l y s i s and the p r e c i s i o n of the chemical methods may not j u s t i f y the time and labour r e q u i r e d . A l s o , even though although the a n a l y t i c a l equipment used was very p r e c i s e , the e x t r a c t i o n s are not d e f i n i t i v e i n t h e i r f r a c t i o n a t i o n of carbohydrate. Where sugar a n a l y s i s was r e q u i r e d , Van Soest and Robertson i n d i c a t e that the Southgate system was probably the best a n a l y t i c a l method a v a i l a b l e . 2.6 SHEEP AS MODELS FOR CATTLE Playne (1978) i n d i c a t e d that i n t a k e and d i g e s t i b i l i t y values f o r low q u a l i t y feeds should not be e x t r a p o l a t e d to c a t t l e from values determined u s i n g sheep since low concentrations of N, S and other n u t r i e n t s r e s u l t i n poorer u t i l i z a t i o n of these feeds by sheep r e l a t i v e to c a t t l e . However, the r e l a t i v e d i f f e r e n c e between forages i n d i g e s t i b i l i t y are reasonably constant regardless of whether they are determined w i t h sheep or c a t t l e except f o r mature, low q u a l i t y m a t e r i a l s of low d i g e s t i b i l i t y (Heaney e_t a l . , 1980) . R e l a t i v e d i f f e r e n c e s i n feed value of forages are s i m i l a r f o r the two animal species even though absolute values may d i f f e r and as a r e s u l t sheep data can be a p p l i e d to c a t t l e . CHAPTER 3 THE VARIETY TRIAL 3.1 MATERIALS AND METHODS In order to assess the v a r i a t i o n i n n u t r i t i o n a l q u a l i t y of forage species and v a r i e t i e s , samples were s e l e c t e d from a l a r g e number of grasses and legumes. These forages were t e s t e d as p a r t of the B r i t i s h Columbia Seed Crop E v a l u a t i o n P r o j e c t conducted from 1981 to 1983 by the B r i t i s h Columbia M i n i s t r y of A g r i c u l t u r e and Food. The samples used i n t h i s study were c o l l e c t e d at Engen, B r i t i s h Columbia ( l o c a t i o n — 124°20' west l o n g i t u d e , 54°3' north l a t i t u d e ) . The species and v a r i e t i e s t e s t e d are shown i n Table 3.1. A l l species were planted on May 28 and 29, 1980. The seeding r a t e was 11.2 kg/ha f o r a l l species except orchard grass which was planted at 13.4 kg/ha. Each species was l a i d out i n a separate set of p l o t s on the s i t e w i t h each v a r i e t y r e p l i c a t e d four times i n a randomized complete b l o c k design. Care was taken to ensure a l l samples were harvested i n a c o n s i s t e n t manner and at s i m i l a r p h e n o l o g i c a l stage over the study p e r i o d . Grasses were harvested at the e a r l y heading stage and legumes at approximately 10% bloom. Harvest dates are shown i n Table 3.2. Harvesting was done using a 2 0.9 m s i c k l e mower to sample a 2.79 m p l o t . The p l o t s were raked and the sample weighed to determine a f r e s h weight. Grab samples of approximately 500g were c o l l e c t e d , stored i n p l a s t i c bags and transported to the P r i n c e George Experimental Farm where they were placed i n a c o o l e r . Subsequently the samples were d r i e d at 42°C f o r 48 hours Table 3.1 Species and V a r i e t i e s Used i n T r i a l Species Legumes A l f a l f a A l s i k e Clover Red Clover V a r i e t i e s V a r i e t i e s V a r i e t i e s Pacer Peace Anchor Anik Tetra Lakeland P a c i f i c Altaswede Grasses Orchardgrass Timothy V a r i e t i e s V a r i e t i e s Kay Chinook S t e r l i n g Sumas Climax Salvo Timfor Toro Table 3.2 Harvest Dates f o r Samples of the V a r i e t y T r i a l Species Year A l f a l f a A l l v a r i e t i e s 1981 J u l y 1 1982 J u l y 8 1983 J u l y 6 Orchard grass A l l v a r i e t i e s June 15 June 18 June 18 Timothy V a r i e t y Climax Salvo Timfor Toro June 29 June 29 June 29 June 29 June 29 June 29 June 29 June 29 June 28 June 13 June 28 June 13 A l s i k e c l o v e r V a r i e t y T e t r a Red c l o v e r J u l y 17 June 29 June 28 V a r i e t y Lakeland P a c i f i c Altaswede June 29 June 29 J u l y 17 June 29 June 29 J u l y 8 June 28 June 28 August 4 and dry matter y i e l d s were determined. Once d r i e d , the samples were stored i n paper bags i n an unheated b u i l d i n g . The samples s e l e c t e d f o r the v a r i e t y t r i a l were r e - s o r t e d from those i n storage and were d r i e d at 42°C f o r 48 hours and ground through a standard No.3 Wiley m i l l using a 1-mm screen. The samples were then analysed chemically f o r n e u t r a l detergent f i b r e (NDF), a c i d detergent f i b r e (ADF) , crude p r o t e i n (CP) and, i n s i t u , f o r nylon bag dry matter disappearance (NBDMD). The V a r i e t y T r i a l had two main o b j e c t i v e s : 1) to assess the v a r i a t i o n i n the n u t r i t i o n a l q u a l i t y between forage species and v a r i e t i e s w i t h i n s p e c i e s , and 2) to assess the v a r i a t i o n i n the n u t r i t i o n a l q u a l i t y of forage species and v a r i e t i e s between years based on la b o r a t o r y a n a l y t i c a l procedures. 3.1.1 DETERMINATIONS As discussed i n the L i t e r a t u r e Review, there are s e v e r a l l a b o r a t o r y a n a l y t i c a l techniques a v a i l a b l e f o r d e s c r i b i n g feed c h a r a c t e r i s t i c s i n order to make an e v a l u a t i o n of the q u a l i t y of a feed. Those techniques used i n t h i s study were chosen f o r s e v e r a l reasons. The major f a c t o r was the r e p r e s e n t a t i o n of a u s e f u l feed c h a r a c t e r i s t i c ( i e . NDF to estimate inta k e or NBDMD to estimate d i g e s t i b i l i t y ) . The second f a c t o r was the ease w i t h which the a n a l y t i c a l technique could be c a r r i e d out and the r e s u l t s i n t e r p r e t a t e d . F i n a l l y , the NBDMD technique was chosen to more f u l l y explore i t s p o t e n t i a l f o r e v a l u a t i n g feeds. Crude p r o t e i n l e v e l s (one f a c t o r i n assessing o v e r a l l forage q u a l i t y ) were determined by the t e c h n i c a l s t a f f at the B r i t i s h Columbia S o i l , Feed and Tissue T e s t i n g l a b o r a t o r y i n Kelowna, B r i t i s h Columbia. S i n g l e samples were analysed u s i n g a Technicon procedure w i t h the n i t r o g e n l e v e l s determined c o l o r i m e t r i c a l l y (AOAC, 1980). A c i d Detergent F i b r e (ADF) l e v e l s (used to estimate forage d i g e s t i b i l i t y ) were a l s o determined by the s t a f f at the B r i t i s h Columbia S o i l , Feed and Tissue T e s t i n g l a b o r a t o r y . S i n g l e samples were analysed according to the technique o u t l i n e d by Goering and Van Soest (1970). M o d i f i c a t i o n s i ncluded the use of 0.5 g of s u b s t r a t e , 50 ml of reagent, and the e l i m i n a t i o n of d e c a l i n from the ADF and NDF and sodium sulphate from the NDF s o l u t i o n . Dry matter determinations were done usi n g approximately 1 g of sample which was d r i e d at 100°C f o r at l e a s t 24 hours. N e u t r a l detergent f i b r e l e v e l s (used to estimate forage intake) were determined according to the method o u t l i n e d by Goering and Van Soest (1970) as modified by Waldern (1971). D u p l i c a t e determinations were made f o r a l l samples. Approximately 0.33 g of sample was a c c u r a t e l y weighed i n t o a tared t e s t tube using an a n a l y t i c a l balance and r e f l u x e d f o r 1 hour i n approximately 33 ml of NDF s o l u t i o n . Nylon bag dry matter determinations (used to estimate r e l a t i v e d i g e s t i b i l i t y ) were done using nylon bags w i t h i n s i d e dimensions of approximately 4 x 8 cm which were f a b r i c a t e d using 40u pore s i z e N i t e x m a t e r i a l (B & S.H. Thompson and Co. L t d . , Town of Mount Royal, Quebec). The edges of the bags were double sewn and the holes sealed using S i l i c o n Seal (Dow Corning Canada L t d . , M i s s i s s a u g a , O n t a r i o ) . One g samples were a c c u r a t e l y weighed i n t o a tared bag using an a n a l y t i c a l balance. The bag had p r e v i o u s l y been d r i e d at 60°C f o r 24 hours, the d r y i n g temperature was s e l e c t e d to prevent damage to the N i t e x m a t e r i a l due to excess heat. P r i o r to weighing, and during t r a n s f e r from the d r y i n g oven to the a n a l y t i c a l balance, a l l bags and samples were placed i n a d e s s i c a t o r . The bags were securely attached to a s a n d - f i l l e d 100 ml p l a s t i c b o t t l e by heavy nylon f i s h i n g l i n e about 15 cm i n l e n g t h . To reduce problems w i t h bags adhering to each other i n the rumen only 6 bags were attached to each b o t t l e and four b o t t l e s (a t o t a l of 24 bags) were placed i n each animal. Each sample, was d u p l i c a t e d i n each of the two animals used as r e p l i c a t e s . Thus four bags were incubated f o r each sample. A l l samples were incubated f o r a 24 hour p e r i o d . The b o t t l e s were put i n t o the animal through a f i s t u l a and were placed each time i n t o the v e n t r a l area of the rumen. The animals used i n t h i s procedure were two Hereford s t e e r s weighing 550 and 600 kgs r e s p e c t i v e l y being fed a r a t i o n of timothy hay along w i t h t r a c e m i n e r a l s a l t and water ad_ l i b i t u m . The s t e e r s were housed i n a heated barn and were f r e e to move about w i t h i n the confines of the s t a l l . Once the b o t t l e s were removed from the rumen at the end of the 24 hour i n c u b a t i o n p e r i o d the bags were washed q u i c k l y to remove any m a t e r i a l adhering to the outside of the bag and the bags were stored at 4° C u n t i l time was a v a i l a b l e f o r more c a r e f u l washing. The bags were removed from the b o t t l e s p r i o r to being washed i n lukewarm water by hand u n t i l the wash water s t r a i n e d from the bag was c l e a r . The bags were then removed from the b o t t l e s and placed i n a d r y i n g oven at 60°C f o r at l e a s t 24 hours, a f t e r which they were weighed using the a n a l y t i c a l balance and the dry matter disappearance c a l c u l a t e d . 3.1.2 EXPERIMENTAL DESIGN AND STATISTICAL ANALYSIS NDF, ADF and CP a n a l y s i s r e s u l t s were s t a t i s t i c a l l y analysed using the f o l l o w i n g l e a s t squares model: Y . M 1 = u + V. + B.,., + T. + V.T, + e..,.,,, l j k l x j ( i ) k 1 k l ( x j k ) where Y ^ = the dependent v a r i a b l e NDF, ADF or CP u = the o v e r a l l mean common to a l l samples = the e f f e c t of the i ' t h v a r i e t y B,,,. = the e f f e c t of the I ' t h p l o t - nested j ( i ) w i t h i n the i ' t h v a r i e t y ( f i r s t e r r o r term) Tfc = the e f f e c t of the k'th year V/T^ = the i n t e r a c t i o n of the i ' t h v a r i e t y w i t h the k'th year e.,,...' the unexplained r e s i d u a l e r r o r l ( i j k ) ^ as s o c i a t e d w i t h each o b s e r v a t i o n . The experimental design was a completely randomized nested s p l i t p l o t i n time. The f a c t o r s analysed i n the 3 x 16 f a c t o r i a l experiment were 3 years and 16 v a r i e t i e s . The same l e a s t squares model and experimental design was used to analyse Type and Species e f f e c t s . NBDMD r e s u l t s f o r v a r i e t y were analysed u s i n g a s l i g h t l y d i f f e r e n t model due to the use of two animals as r e p l i c a t e s . The f o l l o w i n g l e a s t squares model was used f o r the a n a l y s i s : Y = u + V + B.,.N +T. + V^T. + Ar + V.,Ar + T. Ar + V^ArT, i j k r i 3 ( i ) k i k i k i k + e K i j k r ) where Y ^ ^ = t h e dependent v a r i a b l e NBDMD u = the o v e r a l l mean common to a l l the samples V. I j ( i ) T k V.T. 1 k k r V.A T. x r k e K i j k r ) the e f f e c t of the i ' t h v a r i e t y the e f f e c t of the j ' t h p l o t nested w i t h i n the i ' t h v a r i e t y ( f i r s t e r r o r term) the e f f e c t of the k'th year the i n t e r a c t i o n of the i ' t h v a r i e t y w i t h the k'th year A = the e f f e c t of the r ' t h animal the i n t e r a c t i o n of the k'th year w i t h the r ' t h animal the i n t e r a c t i o n of the i ' t h v a r i e t y , the r ' t h animal and the k'th year the unexplained r e s i d u a l e r r o r a s s o c i a t e d w i t h each ob s e r v a t i o n . The experimental design was a completely randomized nested s p l i t p l o t i n time. The f a c t o r s analysed i n the 2 x 3 x 16 f a c t o r i a l experiment were 2 animals, 3 y e a r s , and 16 v a r i e t i e s . The same l e a s t squares model and experimental designs was used to analyse Type and Species e f f e c t s , however the number of f a c t o r s were d i f f e r e n t . For Type the f a c t o r s were 2 Animals, 3 Years and 2 Types and f o r ' Species the f a c t o r s were 2 Animals, 3 Years and 5 Species. In a d d i t i o n to the a n a l y s i s c a r r i e d out using the l e a s t squares models d e s c r i b e d , the NBDMD r e s u l t s were a l s o manipulated to determine i f i t was necessary to analyse the samples using the f i e l d p l o t s as r e p l i c a t i o n s or i f they could be composited. I f the samples f o r each v a r i e t y could be composited by mixing the samples from each f i e l d p l o t together and conducting the a n a l y s i s of v a r i a n c e using the animals as the r e p l i c a t e s fewer NBDMD determinations (4 per v a r i e t y i n s t e a d of 16) would have to be done reducing the workload. This assessment of f i e l d r e p l i c a t i o n s versus animal r e p l i c a t i o n s was done using the data from one year, thus e l i m i n a t i n g year from the model. Two d i f f e r e n t l e a s t squares a n a l y s i s were done based on the f o l l o w i n g models. The f i r s t model (Case One) was the same as that p r e v i o u s l y described to analyse V a r i e t y e f f e c t s by Year. The e r r o r term f o r v a r i e t y was thus p l o t nested w i t h i n v a r i e t y . A second l e a s t squares model was used to evaluate NBDMD r e s u l t s based on the mean value c a l c u l a t e d from the four bags per v a r i e t y placed i n each of the the t e s t s t e e r s (Case Two) . The r e s u l t was the same as i f the samples from a l l p l o t s f o r a v a r i e t y were composited and d u p l i c a t e a n a l y s i s were done i n two animals w i t h the animals being the r e p l i c a t e s . Thus, there were only four bags per v a r i e t y per Year would be used i n s t e a d of the s i x t e e n used i n t h i s experiment. The l e a s t squares model used i s : Y.. = u + V. + e. . where Y „ = the dependent v a r i a b l e u = the o v e r a l l mean common to a l l samples V. = the e f f e c t due to the i ' t h v a r i b l e i e.. = the unexplained r e s i d u a l e r r o r a s s o c i a t e d *3 w i t h each ob s e r v a t i o n . P r i o r to p o o l i n g standard e r r o r s between species ( s i n c e each was grown i n a separate p l o t w i t h i n the experimental area) a t e s t of the homogeneity of vari a n c e s was performed us i n g the B a r t l e t t ' s t e s t ( S t e e l and T o r r i e , 1980). Least squares a n a l y s i s of vari a n c e was done usi n g the General L i n e a r Models (GLM) procedure (SAS, 1985) which allowed f o r manipulation of unbalanced and missing c e l l s . Those sources of v a r i a t i o n w i t h s i g n f i c a n t F values were t e s t e d f o r s i g n f i c a n c e by Student-Newman-Kuels m u l t i p l e comparison of means ( S t e e l and T o r r i e , 1980). 3.1.3 ASSESSMENT OF FEEDING VALUE According to U l y a t t (1973) the feeding value of forage was e s s e n t i a l l y , but not e x c l u s i v e l y based on i n t a k e and d i g e s t i b i l i t y . I n order to assess feeding value based on i n t a k e and d i g e s t i b i l i t y these parameters were estimated u s i n g the f o l l o w i n g equations (Rohweder et a l . 1985): 1) DMD(%) = 88.9 - 0.779 x (ADF%), and 2) DMI(g/kg BW 0* 7 5) = 96.4 - 0.0003 (CP%)- 0.04282(NDF%)-0.0085(NDF% 2) These parameters were m u l t i p l i e d together to develop a Feeding Value Index (FVI) s i m i l a r to that of Crampton et a l . using the f o l l o w i n g equation: FVI = (DDM x DMI)/100. The r e s u l t i n g FVI was used as a b a s i s f o r comparing d i f f e r e n c e s between species and v a r i e t i e s . This index was based on the assumption that DM i n t a k e and d i g e s t i b i l i t y are of equal importance i n determining the feeding value of a forage. 3.1.4 INTEGRATION OF FORAGE QUALITY AND YIELD In order to i n t e g r a t e the y i e l d r e s u l t s f o r each of the Types, Species and V a r i e t i e s w i t h the r e s u l t s of the q u a l i t y determinations, two c a l c u l a t i o n s were made using ADF and CP v a l u e s . The ADF values were used i n an equation developed by Mathison et a l . (1982) to estimate d i g e s t i b l e energy (DE) l e v e l s . This equation i s : DE (Mcals/kg) = 3.44 - 0.22(ADF%) The subsequent DE e s t i m a t i o n was used to o b t a i n a DE y i e l d (DEY) i n the f o l l o w i n g equation; DEY (Meals x 10 3/ha) = DE x Y i e l d No s t a t i s t i c a l a n a l y s i s was done f o r the DE e s t i m a t i o n s s i n c e t h i s i s a t r a n s f o r m a t i o n of the experimental data and there would be no change i n the s t a t i s t i c a l s i g n i f i c a n c e from that obtained u s i n g the f a c t o r (ADF) upon which the DE equation was based ( S t e e l and T o r r i e , 1980). 3.2 RESULTS As mentioned i n S e c t i o n 3.1.1 B a r t l e t t ' s t e s t f o r homogeneity of v a r i a n c e s was done p r i o r to p o o l i n g the standard e r r o r s between species (or s i t e s ) s i n c e each was t e s t e d i n a d i f f e r e n t set of p l o t s w i t h i n the study area. The t e s t i n d i c a t e d the v a r i a n c e s were s i m i l a r and the p o o l i n g of the standard e r r o r s was l e g i t i m a t e . The r e s u l t s are presented by Type (legume or g r a s s ) , Species ( a l f a l f a , orchardgrass, timothy, a l s i k e c l o v e r or red c l o v e r ) and V a r i e t y . 3.2.1 YIELD Y i e l d data were c o l l e c t e d by J.N. T i n g l e and h i s s t a f f during the course of the B r i t i s h Columbia Seed E v a l u a t i o n P r o j e c t and were analysed as p a r t of t h i s study. The r e s u l t s f o r Type and Species are shown i n Table 3.3 For Type, over a l l y e a r s , there was a s i g n i f i c a n t d i f f e r e n c e (P^.0.01) i n y i e l d between legumes and grasses (4.58 ± 0.25 v s . 3.63 ± 0.25 t/ha r e s p e c t i v e l y ) . W i t h i n y e a r s , there was no d i f f e r e n c e (P>0.05) i n y i e l d between the two forage types i n 1981 w h i l e i n both 1982 and 1983 legumes s i g n i f i c a n t l y (P^O.01) o u t - y i e l d e d grasses. Table 3.3 Least Square Means ± SEM̂ ' of Forage Y i e l d s by Type and Species YIELD (t/ha) Designation 1981 Year 1982 1983 A l l Years Type Legumes Grasses Species A l f a l f a Orchardgrass Timothy A l s i k e Clover Red Clover 4.52±0.40a 2.86±0.20b 4.15±0.40a 1 C O A A , n S 3.38±0.41a 2.49+0.403 5.9310.42? 6.9610.80? 5.18+0.49 1.53±0.19a 1.95±0.23a 1.33±0.21a 1.75±0.22a 3.8610.43;* 3.6510.26 6.37±0.29b 5.17±0.293 6.71±0.35 4.10±0.35a 6.2510.35 . 4.94l0.70 a 6.4010.43 4.58t0.25 b 3.63l0.25 a 3.9810.29 2.64i0.28 a 4.6210.29 5.2510.56^ 5.1110.34 D C of the Mean. 11 SEM=Standard E r r o r a,b Means w i t h d i f f e r e n t s u p e r s c r i p t s i n each column and de s i g n a t i o n are s i g n i f i c a n t l y d i f f e r e n t ( P ^ 0 . 0 5 ) . When the r e s u l t s were analysed by Species f o r a l l years a l s i k e c l o v e r (5.25 ± 0.50 t/ha) s i g n i f i c a n t l y (P ̂ 0 . 0 1 ) o u t - y i e l d e d a l f a l f a (3.98 ± 0.29 t / h a ) , orchardgrass (2.64 ± 0.28 t/ha) and timothy (4.62 ± 0.29 t/ha) but was not s i g n i f i c a n t l y d i f f e r e n t from red c l o v e r (5.11 ± 0.34 t / h a ) . In 1981 timothy, a l s i k e and red c l o v e r produced more ( P ^ O . O l ) forage than a l f a l f a and orchardgrass. The r e s u l t s from 1982 were s i m i l a r i n that timothy was not s i g n f i c i a n t l y d i f f e r e n t (P>0.05) from the lower y i e l d i n g a l f a l f a and orchardgrass. In 1983, a l f a l f a , timothy and red cover s i g n i f i c a n t l y o u t - y i e l d e d orchardgrass ( P ^ O . O l ) w h i l e a l s i k e c l o v e r y i e l d s were int e r m e d i a t e . When analysed by v a r i e t y w i t h i n species across a l l years (Table 3.4) there was no s i g n i f i c a n t d i f f e r e n c e ( P > 0 . 0 5 ) between orchardgrass, a l f a l f a or timothy v a r i e t i e s . However, there was a d i f f e r e n c e between red c l o v e r v a r i e t i e s ( P ^ 0 . 0 5 ) . In t h i s case P a c i f i c y i e l d e d much l e s s than Lakeland and Altaswede (2.4±0.10, 4.9±0.10 and 7.9±0.09 t/ha r e s p e c t i v e l y ) . Over a l l y e a r s , i s no s i g n i f i c a n t d i f f e r e n c e (P>0.05) between orchardgrass, a l f a l f a or timothy v a r i e t i e s . Again, there was a s i g n i f i c a n t d i f f e r e n c e (P ^ 0 . 0 5 ) between red c l o v e r v a r i e t i e s w i t h Altaswede out-performing Lakeland which o u t - y i e l d e d the P a c i f i c v a r i e t y . In 1982 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 v a r i e t i e s f o r e i t h e r a l f a l f a , timothy or orchardgrass ( P > 0 . 0 5 ) but w i t h i n the red c l o v e r v a r i e t i e s Altaswede s i g n i f i c a n t l y o u t - y i e l d e d Lakeland which had a s i g n i f i c a n t l y higher y i e l d than P a c i f i c v a r i e t y ( P ^ 0 . 0 5 ) . Orchardgrass v a r i e t i e s were not s i g n i f i c a n t l y d i f f e r e n t i n 1983. However, Climax and Timfor s i g n i f i c a n t l y out performed Salvo and Toro timothy v a r i e t i e s ( P ^ 0 . 0 5 ) . As i n each of the preceding y e a r s , Altaswede s i g n i f i c a n t l y Table 3.4 Least Square Means + SEM of Forage Y i e l d s by V a r i e t y YIELD (t/ha) Species Year and A l l V a r i e t y 1981 1982 1983 Years A l f a l f a Pacer Anchor Peace Anik 3.3+0.5 a b c 3.0±0.5^Dj 3 . 6 i 0 . 6 b c d 3.7±0.5 b c d 2.0±0.4a 1.7+0.3a 1.9±0.3a 2.4±0.4a 6.8±0.4^d, 6.2±0.4 b c d 6.1±0.4 b c d 7.710.4 4.0±0.1 b£ d 3.6±0.1 a b c 3.7±1.0 a b c 4.6±0.1 c d Orchardgrass Kay Chinook S t e r l i n g Sumas 3 . 0 i 0 . 5 a b c 2.4±0.5 a^ C 2.110.5*? 2.4±0.5 a b c 1.7±0.3a l . l + 0 . 3 a 1.4±0.3a 1.0±0.3a 4.4±0.4 a b 3.8+0.4a, 4.2±0.4 a D 4.0±0.4a 3.0±0.l a b 2.5+0.1a 2 . 6 1 0 . l a 2 . 5 1 0 . l a Timothy Climax Timfor Salvo Toro 6 . 3 i 0 . 5 e j l 6.2±0.5" 5.710.5* . 5.4±0.6 d e f 2.0±0.3a 1.9±0.3a 1.7±0.4a 1.4±0.3a 7.4±0.4d 7.6+0.4 . 5.3+0.4 a b G 4.7±0.4 a b 5 . 2 i 0 . 1 d 5.210.C . 4 . 2 1 0 . l b G d 3 . 9 1 0 . l b c d A l s i k e c l o v e r T e t r a 7.0±0.5f 3.9±0.3b 5.0± a b c 5.3+0.1d Red c l o v e r Lakeland Altaswede P a c i f i c 4.6±0.5 c d e 8.7±0.58 1.2+0.6* 3.6±0.4b 5.2±0.3C 2.1±0.3a 6.2+0.4 b c d 9.7±0.4e 4.2±0.4 a b 4 . 9 t 0 . 1 c d 7.910.1 6 2.4+0.l a 1f SEM=Standard E r r o r of the Mean. a,b Means w i t h d i f f e r e n t s u p e r s c r i p t s i n s i g n i f i c a n t l y d i f f e r e n t ( P ^ 0 . 0 5 ) . each column are o u t - y i e l d e d Lakeland and P a c i f i c v a r i e t i e s (P.^0.05). O v e r a l l , Altaswede r e d ^ c l o v e r was c o n s i s t e n t l y the highest y i e l d i n g forage on t e s t producing 8.7 ± 0.5, 5.2 ± 0.3 and 9.7 ± 0.4 t/ha f o r a l l years r e s p e c t i v e l y . In a d d i t i o n , only the red c l o v e r s showed a s i g n i f i c a n t d i f f e r e n c e i n y i e l d s between v a r i e t i e s . There was a s i g n i f i c a n t d i f f e r e n c e i n y i e l d among Years ( P ^ O . O l ) f o r Type, Species and V a r i e t y (Table 3.5) w i t h the y i e l d being highest i n 1983 and lowest i n 1982 ( P ^ 0 . 0 5 ) . • There were s i g n i f i c a n t Type, Species and V a r i e t y x Year ( P ^ O . O l ) i n t e r a c t i o n s . 3.2.2 CRUDE PROTEIN Over a l l years and w i t h i n each year legumes had s i g n i f i c a n t l y higher (P<!0.01) l e v e l s of crude p r o t e i n than grasses (13.7±0.21% vs 9.8+0.21%) (Table 3.6). CP l e v e l s between Species were s i g n i f i c a n t l y d i f f e r e n t (P.^0.01) over a l l years except f o r a l s i k e c l o v e r and red c l o v e r . In descending order were a l f a l f a (14.0 ± 0.22%), a l s i k e c l o v e r (14.0 ± 0.42%), red c l o v e r (13.2 + 0.25%), orchardgrass (10.8 ± 0.22%) and timothy (8.8 ± 0.22%). In 1981 timothy l e v e l s were s i g n i f i c a n t l y lower ( P ^ 0 . 0 5 ) than orchardgrass or a l f a l f a which, i n t u r n , were s i g n i f i c a n t l y lower than the c l o v e r l e v e l s . S i m i l a r r e s u l t s were obtained i n 1982 w i t h the exception 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 (P>0.05) between a l f a l f a and c l o v e r which had the highest CP l e v e l . Each Species was s i g n i f i c a n t l y d i f f e r e n t (P^O.01) f o r CP i n 1983 i n the descending order of A l f a l f a , C l o v e r , Orchardgrass, and Timothy ( P ^ 0 . 0 5 ) . By v a r i e t y across a l l years (Table 3.7) Timfor timothy had s i g n i f i c a n t l y ( P ^ [ 0.05) lower CP l e v e l s than Toro. Kay and Chinook orchardgrass a l s o had s i g n i f i c a n t l y lower l e v e l s of CP than Sumas w i t h Table 3.5 Least Square Means ± SEM of Y i e l d , CP , NDF, ADF, and NBDMD Lev e l s by Year Determinations Yearll Y i e l d CP 1981 4.25 b 10.3 a 1982 2.19 a 11.8 b 1983 5.83° 13.1 C NDF ADF NBDMD 53.5 a 32.7 a 72.3 a 55.7 b 32.0 a 72.8 a 56.6 b 32.7 a 72.4 a SEM 0.1 0.1 0.4 0.3 0.3 11 SEM=Standard E r r o r of the Mean n CP=Crude P r o t e i n , NDF=Neutral Detergent F i b r e , ADF=Acid Detergent F i b r e NBDMD=Nylon Bag Dry Matter Disappearance a,b Means w i t h d i f f e r e n t s u p e r s c r i p t s w i t h i n columns are s i g n i f i c a n t l y d i f f e r e n t ( P ^ 0 . 0 5 ) . Table 3.6 Least Square Means ± SEM of Crude P r o t e i n L e v e l s by Type and Species Crude P r o t e i n L e v e l Year A l l D e signation 1981 1982 1983 Years Type Legumes Grasses 1 1 . 2 ± 0 . 3 3 b 1 3 . 6 ± 0 . 2 4 b 1 6 . 3 ± 0 . 3 4 b 1 3 . 7 1 0 . 2 1 * 9 4 ± 0 3 2 ^ 1 n f** r i <"> rij-rv o;.* n oj.r\ 10.0±0.23£ 9 . 9 ± 0 . 3 4 £ 9 . 8 ± 0 . 2 1 a Species A l f a l f a 10.4+0.32? Orchardgrass 11.0±0.31 Timothy ^ Q * n 0 0 A 1 _ 1. _ A l s i k e Clover Red Clover 7.8±0.32a 11.0±0.63 12.3±0.38C 1 3 . 4 ± 0 . 2 9 f 1 0 . 9 ± 0 . 2 7 9 . 0 ± 0 . 2 8 a 1 4 . 3 ± 0 . 5 4 C 1 3 . 5 ± 0 . 3 2 c 1 8 . 0 ± 0 . 3 3 ^ 1 0 . 4 ± 0 . 3 3 9 . 3 ± 0 . 3 3 a 1 6 . 7 ± 0 . 6 6 1 3 . 9 ± 0 . 3 8 C 1 4 . 0 1 0 . 2 2 ^ 1 0 . 8 ± 0 . 2 1 b 8 . 8 ± 0 . 2 2 a 1 4 . 0 ± 0 . 4 2 c d 1 3 . 2 ± 0 . 2 5 C If SEM=Standard E r r o r of the Mean. a,b Means w i t h d i f f e r e n t s u p e r s c r i p t s i n each column and des i g n a t i o n are s i g n i f i c a n t l y d i f f e r e n t ( P ^ 0 . 0 5 ) . Table 3.7 Least Square Means ± SEM of Crude P r o t e i n Levels by V a r i e t y Crude P r o t e i n (%) Species and Year A l l Years V a r i e t y 1981 1982 1983 A l f a l f a Pacer Anchor Peace Anik 10.1+0.5 b° d 10.0i0.5 b° d 11.5+0.6 ~ j 10.4+0.5 12.7±0.6 c d e 13.310.5° 13.8±0.5Te 14.0+0.6de 17.3±0.6d 18.6+0.6*: 18.8+0.67 17.2+0.6 13.5+0.l g b 14.010.l 8r 14.8+0.14r 13.8+0.I8 Orchardgrass Kay Chinook S t e r l i n g Sumas 9.3+0.5 a b° d 10.810.5° 11.6i0.5 d e 12.2+0.5 10.4+0.5ab 10.4±0.5a£ 11.3+0.5 a b° 11.6±0.5 b c d 10.5±0.6b 9.6±0.6 a b 10.610.6? 11.010.6 i o . n o . i c d 10.210.1° 11.2+0.1 ® 11.6+0.1 Timothy Climax Timfor Salvo Toro 8.0±0.5 a b 7.5+0.53 7.6±0.5\ 8.5±0.6 a b G 8.9+0.53 9.0±0.5a 9.1±0.6a 9.2±0.5a 8.6±0.6 a b 7.9±0.6a 10.1i0.6b 10.910.6 8.510.l a b 8.1±0.1a 8.910.l a b C 9.510.lb° A l s i k e c l o v e r T e t r a 11.0±0.5d 14.3±0.5e 16.7t0.6d 14.010.l g h Red c l o v e r Lakeland Altaswede P a c i f i c de 12.410.5° 11.3+0.5 13.5+0.66 14.5+0.6e 13.3±0.5CJ e 13.0+0.5 14.010.6° 13.110.6C 14.810.6° 13.510.18*1 12.5+0.1 8 13.6+0.18 1[ SEM=Standard E r r o r of the Mean. a,b Means i n each column w i t h d i f f e r e n t s u p e r s c r i p t s are s i g n i f i c a n t l y d i f f e r e n t ( P ^ 0 . 0 5 ) . S t e r l i n g v a r i e t y being intermediate. O v e r a l l , there was no s i g n f i c i a n t d i f f e r e n c e between a l f a l f a or between red c l o v e r v a r i e t i e s ( P > 0 . 0 5 ) . The r e s u l t by v a r i e t y f o r 1981 showed no s i g n i f i c a n t d i f f e r e n c e (P3>0.05) between timothy, orchardgrass or a l f a l f a v a r i e t i e s . P a c i f i c red c l o v e r had s i g n i f i c a n t l y higher ( P ^ 0 . 0 5 ) CP l e v e l s (13.5 ± 0.6%) than Lakeland (12.4 ± 0.5%) or Altaswede (11.3 ± 0.5%) red c l o v e r s or Tetra a l s i k e c l o v e r (11.0 ± 0.5%). In 1982 there were no s i g n i f i c a n t d i f f e r e n c e s (PJ>0.05) i n CP l e v e l f o r timothy, orchardgrass, a l f a l f a or red c l o v e r v a r i e t i e s . However i n 1983 Climax and Timfor v a r i e t i e s were s i g n i f i c a n t l y lower (P^0.05) i n CP l e v e l than Salvo and Toro v a r i e t i e s . There was no d i f f e r e n c e between orchardgrass, c l o v e r or a l f a l f a v a r i e t i e s (P>0.05) f o r CP l e v e l . O v e r a l l , the a l f a l f a v a r i e t i e s and T e t r a a l s i k e c l o v e r had the highest CP l e v e l s , however, there was l i t t l e d i f f e r e n c e between CP l e v e l s of v a r i e t i e s f o r a given species. There was a s i g n i f i c a n t d i f f e r e n c e i n o v e r a l l CP l e v e l s between years (P^O.01) w i t h the highest l e v e l i n 1983 (13.1 ± 0.13%) and the lowest i n 1981 (Table 3.5). There were s i g n i f i c a n t i n t e r a c t i o n s (P^O.01) f o r Type, Species and V a r i e t y by Year. 3.2.3 NEUTRAL DETERGENT FIBRE The r e s u l t s f o r the NDF a n a l y s i s f o r Type and Species are shown i n Table 3.8. O v e r a l l y e a r s , and w i t h i n y e a r s , the grasses had s i g n i f i c a n t l y higher (P^O.01) NDF l e v e l s than the legumes (64.3 ± 0.64 vs. 46.1 ± 0.65%). When examined by Species over a l l y e a r s , each Species was s i g n i f i c a n t l y d i f f e r e n t than the others (P^O.01) w i t h c l o v e r s having the Table 3.8 Least Square Means ± SEM̂ ' of N e u t r a l Detergent F i b r e L e v e l s by Type and Species N e u t r a l Detergent F i b r e L e v e l s (%) Year A l l D e s ignation 1981 1982 1983 Years Type Legumes Grasses Species 47 60 .l±l.lla .1+1.09 44.5±0.59' 66.4±0.57 47.0+0.90 a 46.1±0.65a 66.3±0.87 c/- Q * A t A 64.3±0.64 A l f a l f a 51.0±0.99 Orchardgrass 55.0±0.96*r Timothy 65.5±0.99 A l s i k e Clover 46.5±1.91a Red Clover 42.1±1.15a 44.4+0.63 65.1+0.59C 67.9±0.63{ 38.6±1.17*' 47.0+0.74 c 49.0+1.23 64.5+1.23C 68.1±1.23C 41.2±2.60 45.7±1.36 a ab 48.1±0.63 61.5+0.61*: 67.1±0.63 42.2±1.27a 44.8±0.75a % SEM=Standard E r r o r of the Mean. a,b Means w i t h d i f f e r e n t s u p e r s c r i p t s i n each column and d e s i g n a t i o n are s i g n i f i c a n t l y d i f f e r e n t ( P ^ 0 . 0 5 ) . lowest l e v e l (42.2 ± 1.27 and 44.8 ± 0.75% f o r a l s i k e and red c l o v e r r e s p e c t i v e l y ) a l f a l f a next (48.1 ± 0.65%), then orchardgrass (61.5 ± 0.63%), f o l l o w e d by timothy w i t h the highest NDF l e v e l (67.1 ± 0.65%). The r e s u l t s were a l s o the same by year (P^O.01) w i t h the exception that a l f a l f a ranked intermediate between a l s i k e and red c l o v e r i n 1982. NDF l e v e l s by v a r i e t y are shown i n Table 3.9. Over a l l years there was a s i g n i f i c a n t d i f f e r e n c e (P^O.01) between each of the red c l o v e r v a r i e t i e s w i t h the l e v e l s i n ascending order being Lakeland (41.5 ± 0.91%), P a c i f i c (44.9 ± 0.87%) and Altaswede (48.8 ± 0.87%). Peace a l f a l f a (45.0 ± 0.87%) had s i g n i f i c a n t l y lower (P^0.05) l e v e l s of NDF than Pacer (49.1 ± 0.87%), Anchor (47.9 ± 0.83) or Anik (50.1 ± 0.87%) v a r i e t i e s . There was no s i g n i f i c a n t d i f f e r e n c e s ( P > 0 . 0 5 ) between e i t h e r orchardgrass or timothy v a r i e t i e s . There was some v a r i a t i o n i n red c l o v e r NDF l e v e l s from year to year. In 1981, both Lakeland and P a c i f i c v a r i e t i e s showed s i g n i f i c a n t l y lower (P^0.05) NDF l e v e l s than Altaswede w h i l e i n 1982 there was no s i g n f i c a n t d i f f e r e n c e (P>0.05) between the v a r i e t i e s . Lakeland was s i g n f i c a n t l y lower ( P ^ 0 . 0 5 ) i n NDF than Altaswede i n 1983 and P a c i f i c l e v e l s were intermediate but not s i g n i f i c a n t l y d i f f e r e n t (P.>0.05) from e i t h e r of the other v a r i e t i e s . As w i t h red c l o v e r , there was some year to year v a r i a t i o n w i t h a l f a l f a s . In 1981 Peace i s s i g n i f i c a n t l y lower (P.^0.05) than Anik f o r NDF w h i l e Pacer and Anchor l e v e l were intermediate but not s i g n i f i c a n t l y d i f f e r e n t ( P > 0 . 0 5 ) from Anik. There was no s i g n i f i c a n t d i f f e r e n c e ( P > 0 . 0 5 ) between v a r i e t i e s i n 1982 but there was a trend to higher NDF l e v e l s i n Pacer and Anik. Again, there was no s i g n i f i c a n t d i f f e r e n c e ( P > 0 .05) between a l f a l f a v a r i e t i e s i n 1983 although Pacer Table 3.9 Least Square Means ± SEM of N e u t r a l Detergent F i b r e by V a r i e t y N e u t r a l Detergent (%) F i b r e L e v e l s Species Year A l l V a r i e t y 1981 1982 1983 Years A l f a l f a Pacer Anchor Peace Anik 50.7±1.02 c d 5 0 . 5 i l . 0 2 f d 4 6 . 4 i l . l 8 b 55.011.02 4 6 . 0 i l . 0 7 b c d 43.910.93?° 42.410.93* . 4 6 . 3 t l . 0 7 b c d 51.112.07 C 4 9 . 3 i 2 . 0 7 a b C 4 6 . 8 l 2 . 0 7 a b C 4 8 . 6 i 2 . 0 7 a b C 49.110.87 C 47.9i0.83f 45.010.87 50.110.87 C Orchardgrass Kay Chinook S t e r l i n g Sumas 55.2+1.02 d 5 4 . 7 i l . 0 2 d 5 5 . 2 i l . 0 2 d 54.811.02 68.8t0.93 f 63.0t0.93 6 f 65.110.93 6 63.3t0.93 6 66.4l2.07 d 63.3i2.07 d 63.3i2.07 d 65.012.07 63.510.83 d 6 60.310.83^ 61.210.83 d 61.110.83 Timothy Climax Timfor Salvo Toro 66.311.02 6 6 6 . 7 i l . 0 2 6 6 5 . 6 l l . 0 2 6 6 3 . 0 t l . 1 8 6 67.910.93^ 68.210.93^ 66.9+1.07* 68.411.07 70.4t2.07 d 71.4i2.07 d 65.012.07^ 65.712.07 68.210.83* 68.710.83 65.9t0.83 6:: 66.110.91 6 A l s i k e c l o v e r T e t r a 4 6 . 5 l l . 0 2 b 38.6t0.93 a 41.2t2.39 a b 4 2 . 2 l 0 . 8 7 a b Red c l o v e r Lakeland Altaswede P a c i f i c 3 6 . 7 t l . 0 2 a 50.811.02 3 7 . 7 l l . l 8 a 4 6 . 9 i l . 3 l f d 4 5 . 2 i 0 . 9 3 b C d 48.810.93 40.4t2.07 a 49.912.39 ° 47.812.07 41.5t0.91 a 48.810.87° 44.910.87 II SEM=Standard E r r o r of the Mean. a,b Means w i t h i n columns w i t h d i f f e r e n t s u p e r s c r i p t s are s i g n i f i c a n t l y d i f f e r e n t ( P ^ 0 . 0 5 ) . had s l i g h t l y higher NDF l e v e l s . There was no s i g n i f i c a n t d i f f e r e n c e (P>0.05) between orchard grass or timothy v a r i e t i e s i n 1981 and 1983 or between v a r i e t i e s i n 1982. Kay orchardgrass (68.8 ± 0.93%) had a s i g n i f i c a n t l y higher (P^.0.05) NDF l e v e l i n 1982 than e i t h e r Chinook (63.0 ± 0.93%) or Sumas (63.3 ± 0.93) w h i l e S t e r l i n g (65.1 ± 0.93%) was intermediate but not s i g n i f i c a n t l y d i f f e r e n t (P>0.05) from e i t h e r group. N e u t r a l detergent f i b r e l e v e l s i n 1981 (53.3 ± 0.38%) were s i g n i f i c a n t l y lower (P^0.05) i n 1981 than i n 1982 (55.7 ± 0.40%) or 1983 (56.6 ± 0.38%) as shown i n Table 3.5. There were s i g n i f i c a n t i n t e r a c t i o n s (P^O.01) f o r Type, Species and V a r i e t y x Year. 3.2.4 ACID DETERGENT FIBRE Table 3.10 shows the ADF r e s u l t s by Type and Species. Over a l l years there was no s i g n i f i c a n t d i f f e r e n c e (P>0.05) i n ADF l e v e l between legumes and grasses w i t h determinations of 32.9 ± 0.47% and 32.0 ± 0.46% r e s p e c t i v e l y . The r e s u l t was s i m i l a r i n 1983 but there was a s i g n i f i c a n t d i f f e r e n c e between legumes and grasses i n 1981 and 1982 (P^O.01). When the ADF l e v e l s were examined by s p e c i e s , both orchardgrass (31.0 ± 0.55%) and red c l o v e r (30.9 ± 0.56%) were s i g n i f i c a n t l y lower ( P^0.05) i n ADF than a l f a l f a (34.6 ± 0.57%), timothy (33.1 ± 0.56%) and a l s i k e c l o v e r (32.3 ± 1.10%). ADF l e v e l s i n 1981 f o l l o w e d a s i m i l a r p a t t e r n w i t h the exception that timothy was intermediate to and s i g n i f i c a n t l y d i f f e r e n t (P^0.05) from e i t h e r orchardgrass and red c l o v e r or a l f a l f a and a l s i k e c l o v e r . In 1982 both a l s i k e and red c l o v e r were s i g n i f i c a n t l y lower (P^0.05) than a l f a l f a , orchardgrass or timothy. In 1983 there were no s i g n i f i c a n t d i f f e r e n c e s (P>0.05) between any of the Table 3.10 Least Square Means ± SEM̂ ' of A c i d Detergent F i b r e L e v e l s by Type and Species. A c i d Detergent F i b r e L e v e l s Designation 1981 Year 1982 1983 A l l Years Type Legumes Grasses Species A l f a l f a Orchardgrass Timothy A l s i k e Clover Red Clover 3 4 . 5 ± 0 . 8 5 a 31.1+0.84 3 7 . 0 + 0 . 8 5 C 2 8 . 4 ± 0 . 8 2 a 3 4 . 1 ± 0 . 8 5 3 8 . 2 ± 1 . 6 5 ( 3 0 . 9 ± 0 . 3 8 a 3 3 . 3 ± 0 . 6 7 a 3 2 . 9 ± 0 . 4 7 32 9+0 37 1 1 i *r> ci^ oo n*n i.e. 2 9 . 6 ± 1 . 0 0 a 32.3±0.48? 32.9+0.45? 33.9±0.46 28.2±0.90a 30.2+0.54 3 32.1±0.67a 34.3±0.95a 31.6±0.95a 32.5±0.95a 30.5±1.89a 32.8±1.09a 32.0+0.46 a 34.6±0.57 31.0±0.55a 33.1±o.56? 3 2 . 3 1 1 . 1 0 30.9±0.65a a II SEM=Standard E r r o r of the Mean. a,b Means w i t h d i f f e r e n t s u p e r s c r i p t s i n each column and d e s i g n a t i o n are s i g n i f i c a n t l y d i f f e r e n t ( P ^ 0 . 0 5 ) . species. The ADF r e s u l t s by v a r i e t y (Table 3.11) over a l l years showed no s i g n i f i c a n t d i f f e r e n c e ( P > 0 . 0 5 ) between Lakeland (28.3 ± 0.8%) and P a c i f i c red c l o v e r v a r i e t i e s (29.4 ± 0.8%) although Altaswede red c l o v e r (34.6 ± 0.7%) had a s i g n i f i c a n t l y higher (P^0.05) ADF l e v e l . There was no s i g n i f i c a n t d i f f e r e n c e (P>0.05) between a l f a l f a , orchard-grass and timothy v a r i e t i e s . When the v a r i e t i e s were examined by year Altaswede red c l o v e r i s s i g n i f i c a n t l y g r e a t e r ( P ^ 0 . 0 5 ) i n ADF l e v e l than Lakeland and P a c i f i c v a r i e t i e s i n 1981 and Lakeland v a r i e t i e s i n 1982. There was no s i g n f i c a n t d i f f e r e n c e (P>0.05) between Lakeland . P a c i f i c and Altaswede red c l o v e r i n 1983 although the Altaswede ADF l e v e l s were at l e a s t 6.6 percentage p o i n t s h i g h e r . A l f a l f a ADF l e v e l s i n 1981 were not s i g n i f i c a n t l y d i f f e r e n t ( P > 0 . 0 5 ) . I n 1982 Pacer had s i g n i f i c a n t l y higher values than Peace w h i l e both Anchor and Anik showed intermediate l e v e l s i n 1983 there was again no s i g n i f i c a n t d i f f e r e n c e (P>0.05) between v a r i e t i e s . 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 ( P > 0 . 0 5 ) between orchardgrass v a r i e t i e s i n 1981, 1982 and 1983 or between timothy v a r i e t i e s i n any year except that i n 1983 Salvo was s i g n i f i c a n t l y lower (P.^0.05) i n ADF than Climax, Timfor or Toro v a r i e t i e s . 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 years (Table 3.5) f o r Type and V a r i e t y (P>0.05). However, when analysed by Species there was a s i g n i f i c a n t d i f f e r e n c e between years (P^O.01). Type, Species and V a r i e t y x Year i n t e r a c t i o n s were a l l s i g n i f i c a n t (P^O.Ol) . Table 3.11 Least Square Means ± SEM of A c i d Detergent F i b r e L e v e l s by V a r i e t y A c i d Detergent F i b r e L e v e l s (%) Species and Year A l l V a r i e t y 1981 1982 1983 Years A l f a l f a Pacer Anchor Peace Anik 36.4±l.l e* 8 36.2±l.l e* 8 35.1±1.3 8 39.9±1.18 34.7±0.9d . 31.7±0.7 b° d 30.7±0.7 a b C 33.0±0.9 b c d 36.4±1.6b, 33.6±1.6a? 33.8±1.6 a b 33.5±1.6 a b 35.6±0.8e 33.8±0.7° * 33.1±0.8 b c d e 35.8±0.8e Orchardgrass Kay Chinook S t e r l i n g Sumas 30.0±l.l b c d 27.7±l.la£ 2 8 . 7 + l . l a ? C 26.9±1.1 34.0±0.7 c d 33.5±0.7° 32.3±0.7? C d 31.8±0.7 b c d 32.4±1.6 a b 30.8±1.6 a b 30.2±1.6 a b 33.1±1.6a° b cde 32.2+0.7 30.6±0.7 a b c d 30.4±0.7 a b C\ 30.6±0.7 a b c d Timothy Climax Timfor Salvo Toro 35.0±l.l e f f 34.3±l.l d e* 34.0±l.l d" 32.6±1.3 33.1±0.7 b c d 32.8±0.7 b c d 31.8±0.9 b c d 33.6±0.7 C d 35.4±1.6 a b 35.9±1.6 a D 28.1±1.6a 30.8+1.6 a b 34.5+0.7 c d e 34.3±0.7 C d e, 31.3±0.8 a b c d 32.5±0.8 b c d e A l s i k e c l o v e r T e t r a 38.2±l.l f g 28.2±0.7a 30.5±1.6 a b 32.3±0.7 b c d e Red c l o v e r Lakeland Altaswede P a c i f i c 26.6+1.1*° 36.5±1.1 8 24.5±1.3a 28.1±0.9a, 29.7±0.7 a D, 32.3±0.7 b c d 29.8±1.6 a b 37.6+1.6°. 31.0±1.6 a b 28.3±0.8a 34.6±0.7 J* 29.4+0.8 a b 11 SEM = Standard E r r o r of the Mean. a,b Means w i t h d i f f e r e n t s u p e r s c r i p t s i n each column are s i g n i f i c a n t l y d i f f e r e n t (P$0.05). 3.2.5 NYLON BAG DRY MATTER DISAPPEARANCE Table 3.12 shows the NBDMD r e s u l t s by Type and Species. Over a l l years there was no s i g n i f i c a n t d i f f e r e n c e ( P > 0 . 0 5 ) i n disappearance between legumes and grasses (72.3±0.71 v s . 72.910.73% r e s p e c t i v e l y ) . There was a s i g n i f i c a n t d i f f e r e n c e i n NBDMD between types i n 1981 (P^O.Ol) w i t h values of 68.7 ± 1.26% and 75.8 ± 1.24% and i n 1982, w i t h f i g u r e s of 74.8 ± 0.64 and 71.1 ± 0.62% f o r grasses and legumes r e s p e c t i v e l y . There was no d i f f e r e n c e between Type i n 1983 (P>0 . 0 5 ) . For s p e c i e s , over a l l y e a r s , both a l f a l f a (68.6 ± 0.60%) and timothy (70.0 ± 0.60%) were s i g n i f i c a n t l y d i f f e r e n t ( P ^ 0 . 0 5 ) from orchardgrass (75.7 ± 0.58%), red c l o v e r (76.1 ± 0.71) and a l s i k e c l o v e r (75.9 ± 1.17%). There was some v a r i a t i o n i n r e s u l t s by species from year to year. In 1981 a l l species are s i g n i f i c a n t l y d i f f e r e n t ( P ^ O . O l ) w i t h orchardgrass showing the highest disappearance (81.7 ± 0.99%) and red cl o v e r (75.7 ± 1.11%), timothy (69.6 ± 1.03%), a l s i k e c l o v e r (68.7 ± 1.84) and a l f a l f a (63.6 ± 1.03%) f o l l o w i n g i n descending order. In 1983 a l f a l f a , orchard grass and timothy 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 each other (P>0.05) but were s i g n i f i c a n t l y d i f f e r e n t (P^0.05) from the c l o v e r s . The r e s u l t s by v a r i e t y w i t h i n species f o r red c l o v e r show that Altaswede (71.4 ± 0.08%) NBDMD was s i g n i f i c a n t l y lower (P^0.05) i n dry matter disappearance than e i t h e r Lakeland (79.2 ± 0.88%) or P a c i f i c (77.3 ± 0.84%) over a l l years (Table 3.13). There was no s i g n i f i c a n t d i f f e r e n c e (P>0.05) between a l f a l f a , timothy and orchardgrass v a r i e t i e s . In 1981 red c l o v e r v a r i e t i e s followed a s i m i l a r p a t t e r n w i t h Altaswede NBDMD s i g n i f i c a n t l y lower ( P ^ 0 . 0 5 ) than Lakeland and P a c i f i c Table 3.12 Least Square Means ± SEM of Disappearance L e v e l s by Type Nylon Bag Dry and Species Matter Nylon Bag Dry Matter Disappearance L e v e l s (X) Designation Type 1981 Year 1982 1983 A l l Years Legumes Grasses 68.7±1.26a 75.8+1.24 74.810.64 71.110.62* 73.1±0.95S 72.3±0.72a 71.7±0.95a 7 0 Q + n 7 Q a 72.9±0.73a Species A l f a l f a Orchardgrass Timothy A l s i k e Clover Red Clover 63.6±0.95a 81.710.927 69.610.95? 68.711.84 75.7±1.11C 72.2±0.63b 73.110.59 68.9±0.63a 79.6±1.18 76.410.74° 69.9±1.23 72.2tl.23 71.1+1.23 79.312.45 75.111.42 a ab ab be 68.6t0.60 a 75.710.59 70.0t0.60 a 75.9+1.17^ 76.110.71 II SEM = Standard E r r o r of the Mean. a,b Means w i t h d i f f e r e n t s u p e r s c r i p t s i n each column and d e s i g n a t i o n are s i g n i f i c a n t l y d i f f e r e n t ( P ^ 0 . 0 5 ) . Table 3.13 Least Square Means ± SEM̂ ' of Nylon Bag Dry Matter Disappearancd Levels by V a r i e t y Nylon Bag Dry Matter Disappearance L e v e l s (%) Species and V a r i e t y A l f a l f a Pacer Anchor Peace Anik Orchardgrass Kay Chinook S t e r l i n g Sumas Timothy Climax Timfor Salvo Toro Year A l s i k e c l o v e r T e t r a Red c l o v e r i i Lakeland Altaswede P a c i f i c A l l 1981 1982 1983 Years 63.5±1.2b 65.6±1.2 a b 66.2±1.3 59.7±1.2a 71.1±1.3 a b c d 71.7±l.l a b^ d 73.3±l.l bf d. 72.1±1.3 a b c d 67.2±1.8 a b 69.0±1.8 a? C 71.0+1.8 a? c. 72.4±1.8 a b c d 67.5±0.8a, 68.8+0.8 a? 70.3±0.8a? 68.0±0.8 8 2 . O i l . 2 d 81.1+1.2^ 82.311.2* 81.5±1.2d 72.2±l.l a b c d 71.1±l.l a b c d 7 2 . 8 + l . l a b c d 75.8±l.l c d e 72.3±1.8 a b c d 69.1±1.8 a b C, 72.4±1.8 a b^ d 75.1±1.8 b c d 75.5±0.8 c d 74.0±0.8 C, 75.8+0.8^ 77.5±0.8 70.7±1.2C 69.7+1.2^ 67.9+1.2 70.2±1.3C 70.4±l.l a b c 69.6±l.l a D 67.2±1.3a 67.5±1.3a 66.0±1.8 a 65.8±1.8 a 76.5+1.8°d 76.2+1.8 69.0±0.80 a b 68.4±0.8a? 70.6±0.8a^ 70.7+0.9 68.7±1.2C 79.6±l.le 79.3±1.8d 75.9±0.8°d 80.7±1.2d 67.8+1.2^° 79.6±1.3 76.7±1.6 d e 77.1±l.ld^ 75.5±l.l c d e 79.8±1.8d 69.2+1.8a°° 76.4±1.8 79.2±0.9* 71.4+0.8 77.3+0.8 11 SEM = Standard E r r o r of the Mean. a,b Means w i t h d i f f e r e n t s u p e r s c r i p t s i n each column are s i g n i f i c a n t l y d i f f e r e n t ( P ^ 0 . 0 5 ) . v a r i e t i e s . Anik v a r i e t y a l f a l f a (59.7 ± 1.2%) was s i g n i f i c a n t l y lower (P<0.05) than e i t h e r Pacer (63.5 ± 1.2%), Anchor (65.6 ± 1.2%) or Peace (66.2 ± 1.3%) v a r i e t i e s . There was no s i g n i f i c a n t d i f f e r e n c e (P>0.05) between orchardgrass and timothy v a r i e t i e s . There was no s i g n i f i c a n t d i f f e r e n c e (P>0.05) between red c l o v e r , timothy, orchard grass or a l f a l f a v a r i e t i e s i n 1982. In 1983 Altaswede had was s i g n i f i c a n t l y lower NBDMD l e v e l s (P.^0.05) than Lakeland v a r i e t y . P a c i f i c and Lakeland v a r i e t i e s were not s i g n i f i c a n t l y d i f f e r e n t ( P > 0 . 0 5 ) . There was no s i g n i f i c a n t d i f f e r e n c e (P>0.05) between a l f a l f a and orchardgrass v a r i e t i e s , however, there was some v a r i a t i o n i n timothy v a r i e t i e s . Both Climax (66.0 ± 1.8%) and Timfor (65.8 ± 1.8%) timothy were s i g n i f i c a n t l y d i f f e r e n t (P^0.05) from Salvo (76.5 ± 1.8%) and Toro (76.2 ± 1.8%) v a r i e t i e s . Again the red c l o v e r s continued to show d i f f e r e n c e s between v a r i e t i e s i n a manner c o n s i s t e n t w i t h those seen w i t h previous determinations. Table 3.14 shows the e f f e c t s of year on NBDMD f o r Type, Species and V a r i e t y . 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 Years f o r Type ( P > 0.05), however there was a s i g n i f i c a n t d i f f e r e n c e (P ̂  0.01) between years f o r Species w i t h NBDMD l e v e l s being s i g n i f i c a n t l y lower i n 1981 (P<:0.05) than i n Years 2 or 3 (72.0 ± 0.39, 74.3 ± 0.04 and 73.6 ± 0.38% r e s p e c t i v e l y ) . There was no s i g n i f i c a n t d i f f e r e n c e (P>-0.05) between years f o r v a r i e t y . The r e s u l t s of the e f f e c t of animal on NBDMD are shown i n Table 3.15. Over a l l years there was a s i g n i f i c a n t d i f f e r e n c e ( P ^ O . O l ) between animals f o r Type, Species and V a r i e t y . The r e s u l t s of the Table 3.14 Least Square Means ± SEM of Nylon Bag Dry Matter Disappearance L e v e l s by Year Nylon Bag Dry Matter Disappearance (%) Lev e l s D e s i g n a t i o n Year Type Species V a r i e t y 1981 1982 1983 72.4 a 7 3 . l a 72.4 a 72. Of 74.3 b 73.6 b 72.3 a 72.8 a 72.4 a SEM1' 0.4 0.4 0.4 II SEM=Standard E r r o r of the Mean. a,b Means w i t h d i f f e r e n t s u p e r s c r i p t s i n each column are s i g n i f i c a n t l y d i f f e r e n t ( P ^ 0 . 0 5 ) . Table 3.15 Least Square Means ± SEM of Nylon Bag Dry Matter Disappearance L e v e l by Animal Nylon Bag Dry Matter Disappearance Levels (%) Year A l l D e signation Animal 1981 1982 1983 Years Type 1981 1982 Species 1981 1982 V a r i e t y 1981 1982 72.9±0.33b 73.2±0.38a 73.1±0.33b 73.1±0.34b 71.7±0.33a 72.8±0.38a 71.7±0.33a 72.1±0.34a 73.0±0.35b 74.9±0.31b 74.2±0.36b 74.2±0.32b 70.8±0.35a 73.2±0.31a 72.9±0.36a 72.4±0.32a 72.9±0.3b 73.0±0.3a 73.1±0.3b 73.0±0.2b 71.7±0.3a 72.6±0.3a 71.7±0.3a 72.0±0.2a 1f SEM = Standard E r r o r of the Mean. a,b Means w i t h d i f f e r e n t s u p e r s c r i p t s i n each column and d e s i g n a t i o n are s i g n i f i c a n t l y d i f f e r e n t ( P ^ 0 . 0 5 ) . e f f e c t of animal upon NBDMD by year show there was a s i g n i f i c a n t d i f f e r e n c e (P^O.01) between animals f o r Type, Species and V a r i e t i e s f o r 1981 and 1983. There was no s i g n i f i c a n t d i f f e r e n c e ( P > 0 .05) between animals f o r 1982. The Type x Animal i n t e r a c t i o n was s i g n i f i c a n t i n 1981 and 1982 (P^O.01) but not i n 1983 (P>0.05) or over a l l Years (P 0.05). The Species x Animal i n t e r a c t i o n s were s i g n i f i c a n t (P^O.01) f o r a l l Years. The V a r i e t y x Animal i n t e r a c t i o n was s i g n i f i c a n t (P^O.Ol) over a l l Years and f o r 1981 and 1982 but not f o r 1983 (P>0.05). The Type, Species and V a r i e t y x Year i n t e r a c t i o n s were s i g n i f i c a n t ( P ^ O .01) over a l l Years and w i t h i n Years, however, the Year x Animal i n t e r a c t i o n s f o r Type, Species and V a r i e t y were not s i g n i f i c a n t (P>0.05). i n any of the cases. The Type and Species x Year x Animal i n t e r a c t i o n s were s i g n i f i c a n t (P^O.01) but the V a r i e t y x Year x Animal i n t e r a c t i o n was not s i g n i f i c a n t (P>0.05) . 3.2.6 ASSESSMENT OF THE FEEDING VALUE The r e s u l t s of the FVI c a l c u l a t i o n are shown i n Table 3.16 along w i t h the DMI and DDM values upon which they are based. Timothy v a r i e t i e s have the lowest index w i t h orchardgrass v a r i e t i e s having the next lowest index. Both a l f a l f a and c l o v e r had a higher index than the grasses w i t h the a l f a l f a s having g e n e r a l l y lower values than the c l o v e r s . As expected, the l a r g e s t v a r i a t i o n i n index values occured between the red c l o v e r v a r i e t i e s w i t h a range of 7 index p o i n t s . There was a l s o some v a r i a t i o n between a l f a l f a v a r i e t i e s w i t h Peace indexing 5 p o i n t s higher than Anik (53.2 v s . 48.2 index p o i n t s r e s p e c t i v e l y ) . O v e r a l l P a c i f i c (57.3) and Lakeland (54.2) red c l o v e r v a r i e t i e s had TABLE 3.16 Es t i m a t i o n s of Dry Matter Intake (DMI) , D i g e s t i b l e Dry Matter (DDM) and Feeding Value Index (FVI). ESTIMATIONS V a r i e t y A l f a l f a Pacer Anchor Peace Anik Dry Matter D i g e s t i b l e Intake- ? t. Dry Matter (gm/kg BWU-/:5) (Z) 77.8±0.82 63.1±0.58 79.1+0.78 64.810.67 81.210.57 65.5+0.49 77.011.53 62.611.18 FVI 1111 49.1 51.3 53.2 48.2 Orchardgrass Kay Chinook S t e r l i n g Sumas 64.911.92 66.110.37 68.211.35 66.810.40 67.311.38 67.110.30 67.511.36 66.1+1.52 42.9 45.6 45.2 44.6 Timothy Climax Timfor Salvo Toro 60.110.76 59.510.79 62.810.55 62.810.87 64.310.61 64.510.45 66.410.58 66.110.34 38.6 38.4 41.7 41.5 A l s i k e Clover T e t r a Red Clover Lakeland Altaswede P a c i f i c 83.011.34 84.410.95 78.6+0.76 80.911.08 65.011.21 67.910.22 63.810.89 67.010.38 54.0 57.3 50.1 5420 % DMI = 96.4-(0.0003*CP%)-(0.0482*NDF%)-(0.0085*NDF %) (Rohweder et a l . , 1985). DDM = 88.9-0.779*(ADF%) (Rohweder et a l . , 1985). n FVI =(DMI * DDM)/100. the highest index values f o l l o w e d by Peace (53.2) and Anchor (51.3) a l f a l f a s and, then, f i f t h i n rank, Altaswede red c l o v e r . 3.2.7 INTEGRATION OF FORAGE QUALITY AND YIELD Over a l l Years and w i t h i n each Year the DEY of legumes was s i g n i f i c a n t l y g reater (P^O.01) than that of grasses (Table 3.17). DEY 3 l e v e l s were 12.3 ± 0.66 and 9.8 ± 0.64 Meals x 10 /ha r e s p e c t i v e l y . When examined by s p e c i e s , orchardgrass had the lowest DEY l e v e l (P 0.01) (7.3 ± 0.73 Meals x 10 3/ha), a l f a l f a l e v e l s were intermediate 3 (10.6 ± 0.76 Meals x 10 /ha) and timothy, red and a l s i k e c l o v e r s had the highest l e v e l s (12.4 ± 0.75, 13.9 ± 0.87 and 14.2 ± 1.47 Meals x 10 3/ha r e s p e c t i v e l y ) across a l l years. There was l i t t l e v a r i a t i o n between years w i t h DEY r e s u l t s f o r 1981 the same as those f o r a l l Years. In 1982 timothy l e v e l s were not s i g n i f i c a n t l y d i f f e r e n t (P<:0.05) from a l f a l f a and orchardgrass w h i l e i n 1983 a l f a l f a , timothy and red c l o v e r and orchardgrass and a l s i k e c l o v e r were not s i g n i f i c a n t l y d i f f e r e n t . For V a r i e t i e s w i t h i n species (Table 3.18) the only s i g n i f i c a n t d i f f e r e n c e (P ^ 0 . 0 5 ) over a l l years i n DEY was between red c l o v e r v a r i e t i e s . This was a l s o the case i n 1981 and 1982. However, there was some v a r i a t i o n i n 1983 when Anik a l f a l f a had s i g n i f i c a n t l y higher ( P ^ 0 . 0 5 ) DEY l e v e l s than Anchor and Peace. Climax and Timfor a l s o had s i g n i f i c a n t l y higher DEY l e v e l s than Salvo and Toro timothy v a r i e t i e s . There was a s i g n i f i c a n t d i f f e r e n c e (P^O.01) i n DEY between Years w i t h l e v e l s of 12.6 ± 0.33, 6.9 ± 0.33 and 15.6 ± 0.32 Meals x 10 3/ha f o r a l l years r e s p e c t i v e l y . Type, Species and V a r i e t y x Year i n t e r a c t i o n s were a l s o s i g n i f i c a n t (P^!0.01). S i m i l a r to the case f o r DEY, CPY l e v e l s were s i g n i f i c a n t l y greater (P^O.01) f o r legumes than grasses over a l l years (0.64 ± 0.26 and 0.34 ± Table 3.17 Least Square Means ± SEM1' of D i g e s t i b l e Energy Y i e l d s by Type and Species D i g e s t i b l e Energy Y i e l d s (Meals x 10 3/ha) Designation Type 1981 Year 1982 1983 A l l Years Legumes Grasses 12.0±1.04 11.3+1.03 a 7.8±0.56 4.2±0.54 17.2±0.76 14.1±0.75J b 12.3±0.66 9.8±0.64J Species A l f a l f a Orchardgrass Timothy A l s i k e Clover Red Clover 8.9±1.07a 7.0±1.04a 15.9+1.07? 18.1+2.077 14.1±1.25 5.3±0.65a 3.6±0.61a 4.8±0.65a 10.9±1.217 9.9+0.77 18.1+0.92° 11.2±0.92a 17.0±0.92b° 13.7+1.83 17.4±1.10° 10.6±0.76 7.3±0.73a 12.4±0.75 14.2±1.47° 13.9±0.87° 11 SEM=Standard E r r o r of the Mean. a,b Means w i t h d i f f e r e n t s u p e r s c r i p t s i n each column and d e s i g n a t i o n are s i g n i f i c a n t l y d i f f e r e n t ( P ^ 0 . 0 5 ) . Table 3.18 Least Square Means 1 SEM of D i g e s t i b l e Energy Y i e l d s by V a r i e t y D i g e s t i b l e Energy Y i e l d (Meals x 10 3/ha) Species and Year A l l V a r i e t y 1981 1982 1983 Years A l f a l f a Pacer Anchor Peace Anik 8.611.26? 7.911.26? 9.7il.45?° 9.611.26 5 . 2 l l . 0 5 a b 4.7t0.91 a? 5.2l0.91 a 6 . 4 t l . 0 5 b C 18.111.20^ ff 16.711.20 * 16.511.20 20.811.20 s 1 0 . 5 l 0 . 8 4 b c 9.710.84?° 10.1+0.84°° 12.210.84 Orchardgrass Kay Chinook S t e r l i n g Sumas 8.2±1.26b 6.811.26*7 6 . 0 i l . 2 6 a ? 6 . 9 l l . 2 6 a b 4 . 6 l 0 . 9 1 a b 3.1t0.91 a 3.910.91 2.8t0.91 a ah 11.911.20 1 0 . 6 t l . 2 0 a 11.611.20 1 0 . 9 l l . 2 0 a 8.2t0.65 a b 6.8l0.65 a 7.2i0.65 a 6.9i0.65 a Timothy Climax Timfor Salvo Toro 1 6 . 7 i l . 2 6 d e 16.7±1.26Te 15.311.26* 6 14.811.45 5.4t0.91 a b 5.1i0.91 a? . 4 . 6 l l . 0 5 a ? 3.811.05 1 9 . 8 i l . 2 o j : g 20.211.20^, 14.9H.20 b° d e 12.911.20 14.0i0.65 d 14.010.65 11.610.84° 10.910.88° A l s i k e c l o v e r T e t r a Red c l o v e r Lakeland Altaswede P a c i f i c 1 8 . 1 i l . 2 6 d e 10.9l0.91 d 1 3 . 7 t l . 2 0 a b c d 14.2t0.65 d 13.2il.26°d 23.011.26 3 . 6 t l . 4 5 a 9 . 0 l l . 2 9 c d 1 4 . 5 l 0 . 9 l e , 5.810.91 1 7 . 3 i l . 2 0 d e f g 25.011.38 . 11.711.20 13.5l0.88 d 21 . 0 1 0.65 6 6.8t0.84 a 1[ SEM=Standard E r r o r of the Mean. a,b Means w i t h d i f f e r e n t s u p e r s c r i p t s i n each column are s i g n i f i c a n t l y d i f f e r e n t ( P ^ 0 . 0 5 ) . 0.26 t/ha r e s p e c t i v e l y ) and w i t h i n each year (Table 3.19). Both orchardgrass and timothy had s i g n i f i c a n t l y lower (P^O.Ol) CPY l e v e l s than e i t h e r a l f a l f a , a l s i k e c l o v e r or red c l o v e r . There was however v a r i a t i o n from year to year i n CPY w i t h a l f a l f a and orchardgrass having the lowest l e v e l s i n 1981 w h i l e a l f a l f a had the highest l e v e l i n 1983. Timothy had s i g n i f i c a n t l y higher (P^0.05) CPY l e v e l s than a l f a l f a i n 1981, s i m i l a r l e v e l s i n 1982 and lower l e v e l s i n 1983. A l s i k e and red c l o v e r y i e l d s were not s i g n i f i c a n t l y d i f f e r e n t (P >0.05) i n any Year or over a l l Years. Again as expected, the only species w i t h s i g n i f i c a n t d i f f e r e n c e s ( P ^ 0 . 0 5 ) i n CPY l e v e l s between v a r i e t i e s was red c l o v e r (Table 3.20). These d i f f e r e n c e s occurred both w i t h i n years and over a l l years. There i s no s i g n i f i c a n t d i f f e r e n c e (P>0.05) between V a r i e t i e s w i t h i n e i t h e r a l f a l f a , orchardgrass or timothy species over a l l years or w i t h i n each year. CPY was s i g n i f i c a n t l y d i f f e r e n t (P.^0.05) between years w i t h l e v e l s of 0.42 ± 1.46, 0.26 ± 1.54 and 0.77 ± 1.91 t/ha f o r a l l years r e s p e c t i v e l y . The Type, Species and V a r i e t y x Year i n t e r a c t i o n s were a l s o s i g n i f i c a n t ( P ^ O . O l ) . 3.2.8 NBDMD RESULTS USING PLOTS OR ANIMALS AS REPLICATES The experimental design used f o r e v a l u a t i n g NBDMD l e v e l s between v a r i e t i e s i n t h i s study c a l l e d f o r s i x t e e n nylon bags to be incubated per v a r i e t y per year (2 bags / animal x 2 animals x 4 r e p l i c a t e s ) . Thus, the data were analysed using the f i e l d p l o t samples as the r e p l i c a t e s . In order to attempt to reduce the amount of work i n v o l v e d the r e s u l t s f o r each v a r i e t y were mathematically composited (the mean of the four r e p l i c a t e s per v a r i e t y was determined) and animals were used as r e p l i c a t e s . Even though d u p l i c a t e determinations would s t i l l be done f o r Table 3.19 Least Square Means ± SEM of Crude P r o t e i n Y i e l d s by Type And Species Crude P r o t e i n Y i e l d s (t/ha) Year A l l D e signation 1981 1982 1983 Years Type Legumes Grasses Species A l f a l f a Orchardgrass Timothy A l s i k e Clove Red Clover 0.5010.40 0.37l0.41 £ 0.38±0.28 0.15±0.27' 1.0410.38 0.5010.382 0.6410.26 0.3410.26£ r 0.36i0.47 a 0.27i0.46 a 0.47l0.47* C 0.7710.92 0.6110.55 0.2610.33 0.1410.31 £ 0.1610.32* 0.5510.62 0.4810.37 b 1.2010.45 0.43i0.45 a 0.57t0.45 a 0.8210.89* 0.8910.51 0.6010.35 0.28i0.34 a 0.39l0.35 a 0.7110.68* 0.6610.40 1f SEM=Standard E r r o r of the Mean. a,b Means w i t h d i f f e r e n t s u p e r s c r i p t s i n each column and d e s i g n a t i o n are s i g n i f i c a n t l y d i f f e r e n t ( P ^ 0 . 0 5 ) . Table 3.20 Least Square Means ± SEM of Crude P r o t e i n Y i e l d s by V a r i e t y Crude P r o t e i n Y i e l d (t/ha) Species and Year A l l V a r i e t y 1981 1982 1983 Years A l f a l f a Pacer Anchor Peace Anik 0.33±0.60 a J C d e 0.30±0.60 a b c d* 0.42±0.70 b c d e* 0.39±0.60 b c d e f ah 0.25+0.57 7 0.23±0.50a* 0.26±0.50a 0.33±0.57 1.18+0.746 1.14±0.74e 1.15+0.746 1.32±0.74e • 0.58±0.44eJl 0.56+0.446* 0.58±0.44e* 0.68±0.44 Orchardgrass Kay Chinook S t e r l i n g Sumas 0.28±0.60 a b c d 0.2510.60 a b C 0.25±0.60a* . 0.30±0.60 a b c d e 0.18±0.50a 0.12±0.50a 0.16±0.50a 0.12+0.503 0.45±0.74 a b 0.37±0.74a 0.44+0.74a? 0.44±0.74a 0.31±0.43 a b c 0.2510.43 a 0.28±0.43a* 0.29±0.43 Timothy Climax Timfor Salvo Toro 0.5010.60®f 0.47±0.60r~; . 0.43±0.60 b c d f 0.46+0.60° 0.18±0.50 a b 0.17+0.50 0.15±0.57a 0.13±0.57a 0.64±0.74b° 0.60+0.74 a? C 0.54±0.74a? • 0.51±0.74 a D 0.44±0.43°d 0.41±0.43 ? 0.38±0.44 a b C 0.38±0.47 a D C A l s i k e c l o v e r T etra Red c l o v e r Lakeland Altaswede P a c i f i c 0.77±0.70S 0.59±0.60* 0.99+0.60 0.16+0.703 0.55±0.50d 0.45±0.71 c d 0.70±0.50e 0.28±0.50 0.82±0.74 c d 0.87±0.74d 1.25+0.85® 0.63+0.74 D C 0.71±0.43f 0.64±0.47 e f 0.98±0.43S 0.34+0.44 a D C 1[ SEM=Standard E r r o r of the Mean. a,b Means w i t h d i f f e r e n t s u p e r s c r i p t s i n each column are s i g n i f i c a n t l y d i f f e r e n t ( P ^ 0 . 0 5 ) . each v a r i e t y only 4 bags per v a r i e t y per year would be incubated thereby reducing the work load . Table 3.21 shows the r e s u l t s obtained when data from 1981 were analysed u s i n g the f i e l d p l o t s as r e p l i c a t e s or compositing the f i e l d p l o t samples and usin g the animals as r e p l e c a t e s . In both cases (Case One — F i e l d p l o t samples as r e p l i c a t e s and Case Two — Animals as r e p l i c a t e s ) there was a s i g n i f i c a n t d i f f e r e n c e (P ̂ 0 . 0 1 ) between v a r i e t i e s and i n Case 1 there was a s i g n i f i c a n t d i f f e r e n c e (P^0.05) i n NBDMD l e v e l s between animals. In both cases there was no s i g n i f i c a n t d i f f e r e n c e (P>0.05) between orchardgrass and timothy v a r i e t i e s . There was a s i g n i f i c a n t d i f f e r e n c e ( P ^ 0 . 0 5 ) between a l f a l f a v a r i e t i e s w i t h i n cases and these d i f f e r e n c e s were the same i n both cases. S i m i l a r l y , w i t h i n the c l o v e r s , T e t r a a l s i k e c l o v e r i s not s i g n i f i c a n t l y d i f f e r e n t (P>0.05) from Altaswede red c l o v e r but both were s i g n f i c a n t l y d i f f e r e n t i n both cases (P^0.05) from Lakeland and P a c i f i c red c l o v e r s . 3.2.9 WEATHER Weather data f o r the Engen area (Appendix 1) were su p p l i e d by the B r i t i s h Columbia M i n i s t r y of Environment. The temperature and p r e c i p i t a t i o n data were from the Vanderhoof s t a t i o n and the sunshine data were from the Fort S t. James s t a t i o n . Although the data were not c o l l e c t e d d i r e c t l y from the s i t e Cheesman (Pers. comm.) suggested that "the data should be reasonably r e p r e s e n t a t i v e " . The cumulative hours of sunshine and m i l l i m e t r e s of p r e c i p i t a t i o n f o r May and June (most of the p l o t s were harvested i n June) i n d i c a t e that 1982 was much d r i e r than the other two years of the t r i a l . This was a l s o r e f l e c t e d i n the higher f i g u r e f o r growing degree days f o r 1982. As w e l l , the June mean temperature was much higher i n 1982 than i n e i t h e r 1981 or 1982. Table 3.21 Least Square Means ± SEM f o r Nylon Bag Dry Matter Disappearance Nylon Bag Dry Matter Disappearance (%) Case Case V a r i e t y One^' Two Pacer Anchor Peace Anik 63.5±1.2b 65.7±1.2?° 66.1±1.4 59.7±1.2 a 63.7±1.0b 65.7+1.0? c, 66.2±1.0 b° d 59.7+1.0 a Kay Chinook S t e r l i n g Sumas 81. 1±1.4^ 80.5±1.2d 82.3+1.2*: 81.5+1.2 82.1+1.0* 80.5+1.0* 82.3+1.0; 81.5+1.0 Climax Timfor Salvo Toro 70.7±1.2C 69.7±1.2C 68.5±1.2C 70.4+1.4° 70.7±1.0e 69.7±1.0°^e 68.5±1.0° 70.4±1.0 Tetra Lakeland Altaswede P a c i f i c 68.7+1.2° 80.7±1.2d 67.8±1.2j c 79.7±1.4 68.7±1.0° d e 80.711.0 67 8+1 n e 79.7+1.0* 11 SEM = Standard E r r o r of the Mean 1̂11 Case One = F i e l d p l o t samples used as r e p l i c a t e s (16 b a g s / v a r i e t y ) . Case Two = F i e l d p l o t samples mathematically composited Animals used as r e p l i c a t e s . a,b Means w i t h d i f f e r e n t s u p e r s c r i p t s i n each column are s i g n i f i c a n t l y d i f f e r e n t ( P ^ 0 . 0 5 ) . 3.3 DISCUSSION 3.3.1 YIELD The r e s u l t s i n t h i s study showed that legumes o u t - y i e l d e d grasses i n 2 of 3 Years. S i m i l a r r e s u l t s have been reported by McElgunn et a l . (1972) f o r a l f a l f a and bromegrass but T i n g l e (1975) achieved opposite r e s u l t s i n which Climax timothy produced higher y i e l d s than Altaswede red c l o v e r at McBride, B r i t i s h Columbia. I n the present study the higher legume y i e l d was mainly due to the high production l e v e l of Altaswede red c l o v e r . Otherwise r e s u l t s would be s i m i l a r to those reported by T i n g l e (1975). In the same study ( T i n g l e , 1975) timothy o u t - y i e l d e d orchardgrass and both grasses o u t - y i e l d e d a l f a l f a and red c l o v e r . At Engen, the r e s u l t s were s i m i l a r i n that timothy o u t - y i e l d e d a l f a l f a but d i f f e r e n t i n that both c l o v e r and a l f a l f a produced more forage than orchardgrass. Fairbourne (1983) reported y i e l d s of orchardgrass grown under i r r i g a t e d c o n d i t i o n s that were s l i g h t l y higher than under the dryland c o n d i t i o n s at Engen (3.3 v s . 2.65 t / h a . ) . I t appears that orchardgrass, even under good c o n d i t i o n s , may not be high y i e l d i n g . Another f a c t o r of importance according to Fairbourne (1983) was w i n t e r weather which s t r e s s e d p l a n t s r e s u l t i n g i n considerable v a r i a t i o n i n y i e l d even though the orchardgrass p l a n t s were i r r i g a t e d . T a y l o r (1976) compared the y i e l d s of Sumas, S t e r l i n g and Kay orchardgrass v a r i e t i e s and obtained y i e l d s of 9.0, 8.8 and 7.7 t/ha r e s p e c t i v e l y i n a t e s t at A g a s s i z , B r i t i s h Columbia. This study was done to assess the Sumas v a r i e t y , a mid season v a r i e t y adapted to the lower Fraser V a l l e y and the y i e l d s were much higher than those obtained at Engen. This was f u r t h e r i n d i c a t e d by the y i e l d s obtained by C h i l d e r s et a l . (1978) f o r Chinook, Kay and S t e r l i n g v a r i e t i e s (3.3,3.0 and 2.6 t/ha r e s p e c t i v e l y ) at Lethbridge, A l b e r t a . The c l i m a t e at Engen would be c l o s e r to that at Lethbridge than at Agassiz (Sanderson, 1985) and even though Chinook orchardgrass was described as a w i n t e r hardy v a r i e t y y i e l d s at e i t h e r s i t e d i d not approach those at A g a s s i z . I t would appear that orchardgrass i s not w e l l adapted to the Engen s i t e when compared to the y i e l d s of timothy, a l f a l f a and c l o v e r v a r i e t i e s . However, orchardgrass may be s u i t e d to gr a z i n g as a pasture crop where i t ' s l e a f i n e s s would a s s i s t i n pasture management programs. Lawrence and Warder (1979) reported average y i e l d s over 4 years f o r Climax timothy grown under i r r i g a t e d c o n d i t i o n s of 7.7 t/ha. These were higher than the o v e r a l l y i e l d s f o r a l l the v a r i e t i e s t e s t e d i n t h i s t r i a l although Climax and Timfor produced s i m i l a r l e v e l s i n 1983. S i m i l a r to the Engen r e s u l t s , there was l i t t l e d i f f e r e n c e i n y i e l d s between Salvo and Climax v a r i e t i e s at three s i t e s i n Ontario (5.9 and 5.0, 9.3 and 8.9, and 6.5 and 6.2 t/ha. f o r Salvo and Climax at Ottawa, Guelph and Ridgetown r e s p e c t i v e l y ) even though the absolute y i e l d s v a r i e d ( C h i l d e r s and S u i t o r , 1981). These r e s u l t s suggest that timothy i s w e l l s u i t e d to the Engen area. O v e r a l l there were no s i g n i f i c a n t d i f f e r e n c e s between v a r i e t i e s w i t h i n species of orchardgrass, timothy or a l f a l f a . Only i n the c l o v e r s were there s i g n i f i c a n t d i f f e r e n c e s between v a r i e t i e s . These d i f f e r e n c e s i n y i e l d of the c l o v e r s may i n pa r t be explained by the v a r i a t i o n s i n the environment f o r which they were o r i g i n a l l y developed. T a y l o r (1976) reported that most red c l o v e r v a r i e t i e s are not w e l l adapted to areas c l i m a t i c a l l y d i f f e r e n t from where the v a r i e t y was developed. The Lakeland v a r i e t y was developed i n Wisconsin f o r Wisconsin c o n d i t i o n s 3.3.2 QUALITY DETERMINATIONS The r e s u l t s f o r crude p r o t e i n from t h i s t r i a l are s i m i l a r to those of Mertens (1986), Theander and Aman (1986) and R o l l e r et a l . (1978) who a l l reported that legumes had higher crude p r o t e i n l e v e l s than grasses. For example, Theander and Aman (1986) reported CP l e v e l s f o r grasses and legumes of 14.4 and 8.1% r e s p e c t i v e l y ; s i m i l a r to 13.7% f o r legumes and 9.8% f o r grasses obtained i n t h i s study. In r e l a t i o n to s p e c i e s , Mertens (1986) reported values of 23.4% f o r e a r l y v e g e t a t i v e stage a l f a l f a hay and 14.9% f o r red c l o v e r hay. The d i f f e r e n c e between a l f a l f a and c l o v e r s i n t h i s study was not n e a r l y as la r g e w i t h l e v e l s of 14.0 and 13.2% r e s p e c t i v e l y . S i m i l a r to the r e s u l t s i n t h i s study McQueen (1986) and Aman and Lindgren (1983) obtained higher CP l e v e l s i n orchardgrass than i n timothy at an e a r l y stage of growth. There appear to be few references i n the l i t e r a t u r e to d i f f e r e n t CP l e v e l s between v a r i e t i e s of a forage s p e c i e s . There was l i t t l e d i f f e r e n c e i n CP l e v e l s between Salvo (10.8%), Timfor (11.9%) and Climax (12.8%) v a r i e t i e s reported by McQueen (1986). S i m i l a r r e s u l t s were obtained i n t h i s t r i a l w i t h no s i g n i f i c a n t d i f f e r e n c e between any a l f a l f a or c l o v e r v a r i e t y and only one orchardgrass v a r i e t y (Sumas) over a l l years. There was however, a s i g n i f i c a n t d i f f e r e n c e i n CP l e v e l between years. Since the lowest l e v e l was i n 1981 and the highest i n 1983, weather does not appear to be the main f a c t o r . The CP l e v e l i n grasses i s higher i n 1982 and 1983 than i n 1981 and increased over each year i n legumes. The s i g n i f i c a n t i n t e r a c t i o n s between Year and Type, Species and V a r i e t y may be explained by the change i n the CP l e v e l of a l f a l f a s and c l o v e r s from 1981 to 1983. In the f i r s t year the c l o v e r s and two orchardgrass v a r i e t i e s had higher CP l e v e l s than the a l f a l f a s . In 1982 the l e v e l s had changed so both species of legume had higher CP l e v e l s than orchardgrass. 1983 contrasted w i t h 1981 i n that the a l f a l f a v a r i e t i e s had higher CP l e v e l s than the c l o v e r v a r i e t i e s . Few l i t e r a t u r e values are a v a i l a b l e f o r NDF. Mertens (1986) , Theander and Aman (1980), and R o l l e r et_ a l . (1978) each reported lower NDF l e v e l s i n legumes than i n grasses. The r e s u l t s of t h i s study add f u r t h e r to t h i s g e n e r a l i z a t i o n . Mertens (1986) reported NDF values of 50% and 56% f o r a l f a l f a and red c l o v e r hays r e s p e c t i v e l y w h i l e R o l l e r et a l . (1978) obtained values of 67.5% and 75.7% f o r orchardgrass and timothy r e s p e c t i v e l y . Aman and Lindgren (1983) a l s o reported higher NDF values f o r orchardgrass than timothy (57.9 v s . 62.7%). These l e v e l s vary enough to have a s i g n i f i c a n t impact on in t a k e and agree w i t h the r e s u l t s of t h i s study. The NDF values obtained from the Engen samples are lower than those reported by Mertens (1986) due to the more mature p l a n t m a t e r i a l which he t e s t e d . O v e r a l l , there was l i t t l e d i f f e r e n c e i n NDF values between timothy and orchardgrass v a r i e t i e s . Peace a l f a l f a had lower NDF l e v e l s than the other v a r i e t i e s and each of the red c l o v e r s had d i f f e r e n t NDF l e v e l s . These d i f f e r e n c e s may be due to v a r i a t i o n s i n the s t r a i n developed f o r each cl i m a t e or the p h y s i o l o g i c a l requirement f o r increased f i b r o u s m a t e r i a l i n the p l a n t stem as y i e l d s i ncreased. No data on the v a r i a t i o n of NDF l e v e l s over years was found i n the l i t e r a t u r e . While 1981 l e v e l s (53.5±0.4%) were lower than e i t h e r 1982 (55.7±0.4%) or 1983 (56.6±0.4%) no o v e r a l l trend w i t h i n species or v a r i e t i e s was apparent. The other f i b r e based parameters (ADF and NBDMD) do not vary between years and only the 1981 NDF l e v e l was s i g n i f i c a n t l y orchardgrass v a r i e t i e s had higher CP l e v e l s than the a l f a l f a s . In 1982 the l e v e l s had changed so both species of legume had higher CP l e v e l s than orchardgrass. 1983 contrasted w i t h 1981 i n that the a l f a l f a v a r i e t i e s had higher CP l e v e l s than the c l o v e r v a r i e t i e s . Few l i t e r a t u r e values are a v a i l a b l e f o r NDF. Mertens (1986), Theander and Aman (1980), and R o l l e r et a l . (1978) each reported lower NDF l e v e l s i n legumes than i n grasses. The r e s u l t s of t h i s study add f u r t h e r to t h i s g e n e r a l i z a t i o n . Mertens (1986) reported NDF values of 50% and 56% f o r a l f a l f a and red c l o v e r hays r e s p e c t i v e l y w h i l e R o l l e r et a l . (1978) obtained values of 67.5% and 75.7% f o r orchardgrass and timothy r e s p e c t i v e l y . Aman and Lindgren (1983) a l s o reported higher NDF values f o r orchardgrass than timothy (57.9 v s . 62.7%). These l e v e l s vary enough to have a s i g n i f i c a n t impact on i n t a k e and agree w i t h the r e s u l t s of t h i s study. The NDF values obtained from the Engen samples are lower than those reported by Mertens (1986) due to the more mature p l a n t m a t e r i a l which he t e s t e d . O v e r a l l , there was l i t t l e d i f f e r e n c e i n NDF values between timothy and orchardgrass v a r i e t i e s . Peace a l f a l f a had lower NDF l e v e l s than the other v a r i e t i e s and each of the red c l o v e r s had d i f f e r e n t NDF l e v e l s . These d i f f e r e n c e s may be due to v a r i a t i o n s i n the s t r a i n developed f o r each c l i m a t e or the p h y s i o l o g i c a l requirement f o r increased f i b r o u s m a t e r i a l i n the p l a n t stem as y i e l d s i ncreased. No data on the v a r i a t i o n of NDF l e v e l s over years was found i n the l i t e r a t u r e . While 1981 l e v e l s (53.5±0.4%) were lower than e i t h e r 1982 (55.7±0.4%) or 1983 (56.6±0.4%) no o v e r a l l trend w i t h i n species or v a r i e t i e s was apparent. The other f i b r e based parameters (ADF and NBDMD) do not vary between years and only the 1981 NDF l e v e l was s i g n i f i c a n t l y d i f f e r e n t . The i n t e r a c t i o n between Year and V a r i e t y , Species, Class and Type was a r e s u l t of changes i n NDF l e v e l s of one species r e l a t i v e to another over the t e s t p e r i o d . In 1981 the a l f a l f a v a r i e t i e s had NDF l e v e l s s i m i l a r to orchard grass w h i l e i n 1982 and 1983 the a l f a l f a s had higher values than orchardgrass. U n l i k e NDF l e v e l s , ADF l e v e l s i n the t e s t forages d i d not vary g r e a t l y between legumes and grasses. Theander and Aman (1980) a l s o reported s i m i l a r l e v e l s between grasses and legumes (31.3 vs 32.4%). However, care must be taken when i n t e r p r e t i n g ADF values between grasses and legumes due to the e f f e c t of p h e n o l o g i c a l stage. At the species l e v e l both red c l o v e r and orchardgrass were lower i n ADF than a l s i k e c l o v e r , timothy and a l f a l f a . Aman and Lindgren (1983) a l s o reported s l i g h t l y lower ADF values f o r orchardgrass than timothy (32.6 and 34.1%) cut at the same growth stage. With the exception of the red c l o v e r s there was no d i f f e r e n c e i n ADF l e v e l s between v a r i e t i e s . W i t h i n species McQueen (1986) obtained s i m i l a r r e s u l t s to t h i s study w i t h Salvo (36.3%), Timfor (36.5%) and Climax (38.1%) timothy v a r i e t i e s harvested near the boot stage. As w i t h NDF l e v e l s the v a r i a t i o n i n ADF values between red c l o v e r v a r i e t i e s may be the r e s u l t of the need f o r a d d i t i o n a l f i b r o u s m a t e r i a l to p h y s i c a l l y support the e x t r a p l a n t m a t e r i a l f o r the higher producing Altaswede v a r i e t y or may be due to v a r i a t i o n i n red c l o v e r s t r a i n s due to the v a r i a t i o n i n cli m a t e s f o r which they were developed. There was no d i f f e r e n c e i n ADF values between years over a l l sp e c i e s , however there were s i g n i f i c a n t Type, Species and V a r i e t y i n t e r a c t i o n s w i t h Year. This r e s u l t occurred because grasses had higher ADF l e v e l s than legumes i n 1982, p o s s i b l y as a r e s u l t of higher temperatures a f f e c t i n g f i b r e production w i t h i n the p l a n t . In the other years legumes tended to have higher ADF values than grasses. As w i t h ADF l e v e l s , NBDMD values d i d not vary between grasses and legumes. R o l l e r e_t a l . (1978) obtained somewhat d i f f e r e n t r e s u l t s w i t h NBDMD l e v e l s of 88.8±1.0% f o r a l f a l f a , 71.7±1.2% f o r orchardgrass and 52.2+2.0% f o r timothy f o r a 24 hour i n c u b a t i o n p e r i o d . Thus, i n a d d i t i o n to the higher NBDMD l e v e l s f o r a l f a l f a s r a t h e r than grasses, he a l s o obtained much more v a r i e d r e s u l t s between these species than was obtained w i t h the Engen samples. In t h i s study, the c l o v e r s (76.1±0.71%) and orchardgrass (75.7±0.59%) , and timothy (70.0±0.60%) and a l f a l f a (68.6±0.60%) had l e s s v a r i e d disappearance v a l u e s . Seone et ad. (1981b) reported NBDMD values (24 hour incubation) f o r Toro, Climax and Timfor timothy v a r i e t i e s of 45.4, 35.7 and 38.0% r e s p e c t i v e l y . McQueen (1986), a l s o using a 24 hour i n c u b a t i o n reported NBDMD values f o r Toro and Climax timothy v a r i e t i e s of 40 and 45% r e s p e c t i v e l y . These l e v e l s are consider a b l y lower than those values obtained i n t h i s study and may be explained i n the case of McQueen by the more mature samples used r e s u l t i n g i n higher ADF l e v e l s (Toro and Climax — 44.3 and 47.5% compared w i t h ADF l e v e l s of 32.5 and 34.5 obtained i n t h i s study) and lower NBDMD. In the case of Seone e_t a l . (1981b) bags w i t h a much smaller pore s i z e (5 u vs. 40 u pore s i z e f o r bags used i n t h i s study) i n t h e i r experiment would r e s u l t i n much lower NBDMD l e v e l s . As w i t h NDF and ADF determinations there was no d i f f e r e n c e i n NBDMD values between v a r i e t i e s w i t h i n species except f o r the red c l o v e r s . As expected, Altaswede v a r i e t y had the lowest disappearance l e v e l i n keeping w i t h the higher NDF and ADF l e v e l s r e l a t i v e to the other red c l o v e r v a r i e t i e s . There was a s i g n i f i c a n t d i f f e r e n c e between t e s t animal f o r NBDMD r e s u l t s f o r a l l d e s i g n a t i o n s . This may have been due to d i f f e r e n c e s i n DMI r e l a t i v e to the other y e a r l i n g s t e e r s on the Experimental Farm. One animal had a much lower DM i n t a k e r e l a t i v e to the herd average (D. Croy, Pers. Comm.). There was no s i g n i f i c a n t i n t e r a c t i o n between Year and Animal. There was no s i g n i f i c a n t v a r i a t i o n i n NBDMD l e v e l s due to year f o r Type and V a r i e t y . There was a d i f f e r e n c e between years f o r Species due p o s s i b l y to the v a r i a t i o n i n a l s i k e c l o v e r l e v e l s which were lower i n disappearance i n 1981 than orchardgrass and timothy but had higher l e v e l s than e i t h e r i n 1982 and 1983. There was an i n t e r a c t i o n between Year and Type, Species and V a r i e t y . The Type x Year i n t e r a c t i o n was due to grasses having a higher NBDMD value i n 1981 (75.8±1.24 v s . 68.7±1.26% r e s p e c t i v e l y ) and the legumes having a higher value i n 1982 (74.8±0.64 vs 71.1±0.62% r e s p e c t i v e l y ) . In year 3 NBDMD l e v e l s were s i m i l a r f o r grasses and legumes (71.1±0.95 and 73.1±0.95 r e s p e c t i v e l y ) . This would a l s o e x p l a i n the Species and V a r i e t y by Year i n t e r a c t i o n s . The i n t e r a c t i o n between Type, Species and V a r i e t y and Animal (while s t a t i s t i c a l l y s i g n i f i c a n t ) does not appear to be of great importance s i n c e Animal 1 always showed greater disappearance l e v e l s than Animal 2 (73.1±0.34 v s . 72.1±0.34% r e s p e c t i v e l y f o r Type). The only v a r i a t i o n was i n the r e l a t i v e d i f f e r e n c e i n disappearance l e v e l s between those samples incubated i n Animal 1 and Animal 2 f o r samples c o l l e c t e d i n d i f f e r e n t years. The v a r i a t i o n i n NBDMD l e v e l s of grasses r e l a t i v e to legumes over the 3 study years may a l s o e x p l a i n the s i g n i f i c a n t Type and Species x Animal x Year i n t e r a c t i o n s . The V a r i e t y x Animal x Year i n t e r a c t i o n i s not s i g n i f i c a n t . 3.3.3 ASSESSMENT OF FORAGE QUALITY Crude p r o t e i n was a p o s i t i v e i n d i c a t o r of forage q u a l i t y w h i l e NDF was i n v e r s e l y r e l a t e d to i n t a k e , ADF was i n v e r s e l y r e l a t e d to d i g e s t i b i l i t y (Van Soest, 1982) and NBDMD r e f l e c t s the d i g e s t i b i l i t i e s of one forage r e l a t i v e to another (Aerts e_t a l . , 1977). Using the CP, NDF, ADF and NBDMD determinations c a r r i e d out i n t h i s t r i a l the feeding value of one forage r e l a t i v e to another should be estimated w i t h some r e l i a b i l i t y . In c o n s i d e r i n g the r e l a t i v e forage q u a l i t y of legumes compared w i t h grasses NDF and CP l e v e l s become important because o v e r a l l there was no d i f f e r e n c e between the two types f o r NBDMD or ADF determinations. Therefore, i t can be assumed that o v e r a l l d i g e s t i b i l i t i e s w i l l be s i m i l a r f o r the Engen samples. However, DMI w i l l be greater f o r legumes than grasses and t h i s f a c t , coupled w i t h higher CP l e v e l s , i n d i c a t e that legumes w i l l be n u t r i t i o n a l l y s u p e r i o r to the grasses evaluated i n t h i s study. This c o n c l u s i o n was reached s i n c e the animal w i l l o b t a i n more d i g e s t i b l e n u t r i e n t s from the legumes than from the grasses and f o l l o w s r e p o r t s i n the l i t e r a t u r e that i n t a k e of legumes was g e n e r a l l y greater than grasses of the same d i g e s t i b i l i t y (Minson, 1982). In terms of species NBDMD and ADF values i n d i c a t e that orchardgrass was more d i g e s t i b l e than timothy and that the c l o v e r s are more d i g e s t i b l e than a l f a l f a . NDF values i n d i c a t e that orchardgrass would be consumed more r e a d i l y than the timothy and the c l o v e r s more r e a d i l y than a l f a l f a . In a d d i t i o n , CP l e v e l s f o r orchardgrass were higher than f o r timothy so that i t may be concluded that orchardgrass was n u t r i t i o n a l l y s u p e r i o r to timothy i n t h i s study. Even though a l f a l f a had a higher CP l e v e l then the c l o v e r s (14.0 v s . 13.3) i t can be concluded that c l o v e r was n u t r i t i o n a l l y s u p e r i o r to a l f a l f a . Orchardgrass and c l o v e r were of b e t t e r q u a l i t y because they would be eaten i n grea t e r amounts than timothy and a l f a l f a and would be more d i g e s t i b l e . Therefore, i n descending order of n u t r i t i o n a l q u a l i t y , would be c l o v e r s , followed by a l f a l f a , then orchardgrass and f i n a l l y timothy. When c o n s i d e r i n g i n t a k e and d i g e s t i b i l i t y f a c t o r s between v a r i e t i e s w i t h i n species only the red c l o v e r v a r i e t i e s show s i g n i f i c a n t d i f f e r e n c e s . Since Altaswede had lower NBDMD and higher ADF values than e i t h e r Lakeland or P a c i f i c v a r i e t i e s i t might be concluded that i t was the l e a s t d i g e s t i b l e red c l o v e r v a r i e t y . Altaswede would a l s o be eaten i n l e s s e r amounts than the other two v a r i e t i e s (as evidenced by a higher NDF l e v e l ) so that i n terms of n u t r i t i o n a l q u a l i t y , even though there was no d i f f e r e n c e between any of the v a r i e t i e s i n CP l e v e l , P a c i f i c and Lakeland v a r i e t i e s were of b e t t e r n u t r i t i o n a l q u a l i t y than Altaswede. NDF values f o r Peace a l f a l f a i n d i c a t e i t would be consumed at higher l e v e l s than the other a l f a l f a v a r i e t i e s , however, i n terms of d i g e s t i b i l i t y and CP l e v e l s there was no d i f f e r e n c e between any of the a l f a l f a v a r i e t i e s . NBDMD l e v e l s suggest that Sumas orchardgrass would be more d i g e s t i b l e than Chinook v a r i e t y , however, ADF l e v e l s d i d not suggest such a d i f f e r e n c e . Crude p r o t e i n l e v e l s f o r the Sumas v a r i e t y were a l s o higher than the other v a r i e t i e s p o i n t i n g to a p o s s i b l e d i f f e r e n c e between orchardgrass v a r i e t i e s w i t h Sumas being somewhat s u p e r i o r i n n u t r i t i o n a l q u a l i t y . The only v a r i a t i o n between timothy v a r i e t i e s f o r any of the determinations was i n CP l e v e l f o r Toro which was higher than Timfor. O v e r a l l there was no d i f f e r e n c e i n q u a l i t y between timothy v a r i e t i e s . Thus, w i t h the exception of Lakeland and P a c i f i c red c l o v e r s being s u p e r i o r to Altaswede red c l o v e r i t can be. concluded that there was no d i f f e r e n c e i n n u t r i t i o n a l q u a l i t y between v a r i e t i e s w i t h i n species. Therefore, any of the a l f a l f a v a r i e t i e s were s u p e r i o r to any of the orchardgrass v a r i e t i e s which, i n t u r n , we s u p e r i o r to any of the timothy v a r i e t i e s . Heaney et_ al_. (1966) found that the r a t e of d e c l i n e of DMI (as i n d i c a t e d by NDF) was a f f e c t e d more than d i g e s t i b i l i t y (as i n d i c a t e d by ADF) by year-to-year f l u c t u a t i o n s i n growing c o n d i t i o n s . Heaney et^ a l . (1966) suggested that greater v a r i a b i l i t y would occur i n i n t a k e than i n d i g e s t i b i l i t y o v e r a l l and e s p e c i a l l y between years. This i s the case i n the present study. These authors a l s o had s i m i l a r r e s u l t s w i t h v a r i e t i e s i n t hat the d i f f e r e n c e s i n v a r i e t a l d i g e s t i b i l i t i e s were minor and i n c o n s i s t e n t between years. 3.3.4 ASSESSMENT OF FEEDING VALUE Weighing the i n t a k e and d i g e s t i b i l i t y r e s u l t s evenly i n the FVI suggested that the feeding'value of Altaswede red c l o v e r , which had the highest y i e l d s of DE and CP, was lower than any of the other c l o v e r s . The c l o v e r s however, s t i l l had the highest feeding value s i n c e both i n t a k e and d i g e s t i b i l i t y were higher than f o r the other species. A l f a l f a would be the second best species i n terms of feeding value s i n c e i n t a k e would be much higher and DDM was only s l i g h t l y lower than f o r e i t h e r of the grasses. Orchardgrass would have a higher feeding value than timothy s i n c e both DMI and DDM were higher f o r orchardgrass. As was the case w i t h the q u a l i t y parameters there would be l i t t l e d i f f e r e n c e f o r e i t h e r DMI or DDM f o r the v a r i e t i e s w i t h i n each species s i n c e these estimates are based on NDF and ADF determinations r e s p e c t i v e l y . For the same reason i t would be expected that feeding value r e s u l t s would c l o s e l y p a r a l l e l the r e s u l t s suggested by the q u a l i t y determinations. 3.3.5 INTEGRATION OF FORAGE QUALITY AND YIELD When y i e l d was i n t e g r a t e d w i t h the DE estimate ( d i g e s t i b l e energy y i e l d s ) there were some d i f e r e n c e s i n the conclusions that r e s u l t when only q u a l i t y parameters are examined. I t was concluded t h a t , o v e r a l l , the c l o v e r v a r i e t i e s were the highest q u a l i t y , f o l l owed by a l f a l f a then orchardgrass and f i n a l l y t imothy. The DEY r e s u l t s show that one of the best q u a l i t y forages, P a c i f i c red c l o v e r , y i e l d s very low l e v e l s of DE and that Altaswede red c l o v e r , second i n terms of q u a l i t y , produces s u b s t a n t i a l l y more DE than any other species or v a r i e t y . Timothy, which was the lowest q u a l i t y forage, produced equal l e v e l s of DE to the c l o v e r s (except P a c i f i c ) and s u p e r i o r l e v e l s to both a l f a l f a and orchardgrass. In terms of DEY the c l o v e r s and timothy had higher l e v e l s than a l f a l f a and orchardgrass had the lowest l e v e l s . When y i e l d was taken i n t o c o n s i d e r a t i o n there was some v a r i a t i o n between v a r i e t i e s w i t h Salvo and Toro timothy producing l e s s DE than Climax and Timfor v a r i e t i e s . Anchor a l f a l f a produced l e s s DE than Anik w h i l e Sumas and Chinook orchardgrass produced l e s s DE than Kay v a r i e t y . When CPY r e s u l t s were examined there were a l s o d i f f e r e n c e s i n the c o n c l u s i o n drawn when only q u a l i t y parameters are assessed. As was the case w i t h DEY, Altaswede red c l o v e r y i e l d e d the highest amount of CP w i t h P a c i f i c v a r i e t y producing at much lower l e v e l s . A l f a l f a produced s i m i l a r l e v e l s of CP to the c l o v e r s and both a l f a l f a and c l o v e r had greater CPY l e v e l s than timothy and orchardgrass. Timothy y i e l d e d more CP than orchardgrass i n a s i m i l a r s i t u a t i o n to that which occurred w i t h DEY. These r e s u l t s showed t h a t , f o r those Types, Species and V a r i e t i e s s t u d i e d , y i e l d alone was a good c r i t e r i a f o r s e l e c t i n g the forage species and v a r i e t y . This was due to the d e s i r e to o b t a i n the highest l e v e l of usable n u t r i e n t s per hectare of land w h i l e s t i l l h a r v e s t i n g at a phe n o l o g i c a l stage that provides optimum q u a l i t y . The end r e s u l t was the most n u t r i e n t s f o r animal production from the sm a l l e s t area. 3.3.6 NBDMD RESULTS USING PLOTS OR ANIMALS AS REPLICATES The r e s u l t s of t h i s p o r t i o n of the study i n d i c a t e that there was no d i f f e r e n c e i n the assessment of v a r i e t i e s and species when forage samples were analysed f o r NBDMD i n e i t h e r Case 1 or Case 2. In Case 1 the NBDMD r e s u l t s were analysed based on the a c t u a l f i e l d p l o t samples w h i l e i n Case 2 the samples were mathematically composited by t a k i n g the mean value of the 4 f i e l d p l o t r e p l i c a t e s and s t a t i s t i c a l l y a n a l y s i n g them as s i n g l e data p o i n t s . Since there was no d i f f e r e n c e between the two cases i n s t a t i s t i c a l s i g n i f i c a n c e between v a r i e t i e s w i t h i n species i t would reduce the work load to 4 nylon bags per treatment ( d u p l i c a t e samples i n each animal) r a t h e r than the 16 bags used i n t h i s study ( d u p l i c a t e samples i n each animal f o r each f i e l d r e p l i c a t e p l o t ) . This c o n c l u s i o n appears to be v a l i d even though fewer degrees of freedom would r e s u l t i n the need to o b t a i n l a r g e r F values i n the ANOVA and l e s s p r e c i s i o n i n means se p a r a t i o n (Table 3.21). The d i f f e r e n c e s i n NBDMD l e v e l s between Altaswede and Lakeland and P a c i f i c red c l o v e r i n d i c a t e t h a t , even w i t h fewer observations, r e l i a b l e d i f f e r e n c e s would be determined. CHAPTER 4 FEEDING TRIAL 4.1 MATERIAL AND METHODS 4.1.1 FORAGES In order to assess the n u t r i t i o n a l q u a l i t y of two forage mixtures harvested at three d i f f e r e n t growth stages two 0.5 ha p l o t s were planted i n the s p r i n g . of 1983 w i t h forage mixtures intended to mature at d i f f e r e n t times i n the growing season. The e a r l i e r maturing forage mixture (EM) c o n s i s t e d of Tetra a l s i k e c l o v e r , Toro timothy and Manchar bromegrass and the l a t e r maturing forage mixture (LM) c o n s i s t e d of Altaswede red c l o v e r and Climax timothy. Agronomic p r a c t i c e s were those 4 recommended f o r the area and crop. The p l o t s were f e r t i l i z e d w i t h 34-0-0-11 at the r a t e of 180 kg/ha i n the s p r i n g p r i o r to har v e s t . Each p l o t was harvested i n 1984 at 10%, 50% and 100% of legume bloom ( e a r l y bloom, EB; mid bloom, MB; f u l l bloom, FB). Table 4.1 shows the harvest dates and y i e l d s f o r each of the hay c u t s . Forages were f i e l d - c u r e d and three of the s i x samples r e c i e v e d some p r e c i p i t a t i o n w h i l e being d r i e d (EM-EB,EM-FB and LM-EB). Once cured, the hay was baled i n t o s m a l l square b a l e s and transported to the P r i n c e George Experimental Farm where i t was stored under cover i n the barn where the feeding t r i a l was conducted. The o b j e c t i v e s of the feeding t r i a l were: 1) to assess the e f f e c t on.animal i n t a k e and d i g e s t i b i l i t y of an e a r l y and a l a t e maturing forage mixture, and; 2) to assess the e f f e c t on animal i n t a k e and d i g e s t i b i l i t y of ha r v e s t i n g at the e a r l y , mid and f u l l bloom growth stages of the legume component of each forage mixture. Table 4.1 Harvest Date and Y i e l d of Test Forages Hay Mix Harvest Date Y i e l d (T/ha) ++ E a r l y Maturing (EM) + E a r l y Bloom (EB) Mid Bloom (MB) F u l l Bloom (FB) Late Maturing (LM) E a r l y Bloom (EB) Mid Bloom (MB) F u l l Bloom (FB) 1111 J u l y 9 J u l y 15 J u l y 22 J u l y 22 J u l y 30 August 8 5.6 7.6 9.4 9.2 9.9 11.0 11 + EM = a l s i k e c l o v e r - timothy - bromegrass forage mix. ++ EB,MB,LB = 102,50% 100% of bloom of the legume component of the forage mix. 11 Estimate f o r EM-EB based on known weight of a i r dry m a t e r i a l removed from 0.1 ha. 1111 LM = red c l o v e r - timothy forage mix. 4.1.2 EXPERIMENTAL DESIGN AND STATISTICAL ANALYSIS This experiment evaluated the i n t a k e and d i g e s t i b i l i t y of two forage mixes each cut at three stages of growth. Thus, there were s i x treatment combinations. Since i n t a k e and d i g e s t i b i l i t y vary between animals i t was d e s i r a b l e to t e s t each treatment combination w i t h each animal. In t u r n , v a r i a b i l i t y may a r i s e due to t e s t periods s i n c e considerable time may elapse from the beginning to the end of the experiment. Therefore, i n a d d i t i o n to treatment e f f e c t s the v a r i b i l i t y due to animal and p e r i o d was a l s o accounted f o r . The in t a k e and d i g e s t i b i l i t y of the s i x treatment combinations was analysed as a 2x3 f a c t o r i a l experiment i n a 6x6 L a t i n square design. The f a c t o r s used i n the experiment were: 1) 1982 forages mixes; a) E a r l y Maturing (EM), b) Late Maturing (LM), and 2) Three harvest dates; a) ' 10% Bloom (EB), b) 50% Bloom (MB), c) 100% Bloom (FB). The f o l l o w i n g l e a s t squares model was used to analyse a l l of the data i n the feeding t r i a l : Y i j k i • u + A i + p j + \ + H i + ¥ i + e i j k i where = the dependent v a r i a b l e i n t a k e and d i g e s t i b i l i t y , u = the o v e r a l l mean common to a l l samples A. = the e f f e c t due to the i ' t h animal 1 P_. = the e f f e c t due to the j ' t h p e r i o d = the e f f e c t of the k'th forage mix = the e f f e c t of the l ' t h harvest M^H^ = the i n t e r a c t i o n of the k'th forage mix w i t h the l ' t h harvest e ^ j j ^ = the unexplained r e s i d u a l e r r o r a s s o c i a t e d w i t h each sample. As i n the v a r i e t y t r i a l a n a l y s i s of v a r i a n c e was done usi n g the General L i n e a r Models (GLM) procedure (SAS, 1985). Those sources of v a r i a t i o n w i t h s i g n i f i c a n t F values were t e s t e d f o r s i g n i f i c a n c e by Student-Newman-Kuels m u l t i p l e comparison of means ( S t e e l and T o r r i e , 1980). In a d d i t i o n , the RSQUARE procedure (SAS, 1985) was used to determine i f m u l t i p l e f a c t o r r e g r e s s i o n equations could be developed to p r e d i c t the above parameters. 4.1.3. INTAKE AND DIGESTIBILITY TRIAL METHODOLOGY S i x wether sheep were placed i n metabolism c r a t e s designed f o r i n d i v i d u a l feeding and f e c a l c o l l e c t i o n . Each animal had access to t r a c e m i n e r a l s a l t and water and a l l animals were weighed at the end of each p e r i o d . P r i o r to feeding a l l forages were chopped through a 2.5 cm screen i n a hammer m i l l . The forages were fed twice d a i l y at 08:30 and 16:00 h. Samples of each chopped forage were taken weekly f o r a n a l y s i s and stored i n a f r e e z e r u n t i l analysed. Each of the 6 t e s t periods c o n s i s t e d of 5 days f o r adjustment to the new feed, 7 days f o r ad l i b i t u m feed i n t a k e , 3 days f o r adjustment to 70% of ad_ l i b i t u m i n t a k e followed by 6 days f o r f e c a l c o l l e c t i o n . The sheep were fed at 08:30 each day a f t e r which f e c a l samples and o r t s were c o l l e c t e d . Feed o f f e r e d each day was adjusted so that the l e v e l of o r t s remained at about 10% of i n t a k e . T o t a l c o l l e c t i o n of the o r t s during the ad l i b i t u m i n t a k e p e r i o d was done and and the m a t e r i a l stored i n a f r e e z e r u n t i l analysed. Feces were c o l l e c t e d and weighed d a i l y and a r e p r e s e n t a t i v e sample of 20% of d a i l y f e c a l output was c o l l e c t e d . F e c a l samples were added to previous subsamples and returned to the f r e e z e r a f t e r each days c o l l e c t i o n . Orts and f e c a l samples were composited w i t h i n p e r i o d s . Feed, o r t s and f e c a l samples were d r i e d at 45°C f o r 48 hours and ground through a 1 mm screen u s i n g a Wiley m i l l p r i o r to f u r t h e r a n a l y s i s . 4.1.4. ANIMAL MANAGEMENT Seven S u f f o l k wether lambs were purchased about 6 weeks before the s t a r t of the t r i a l . When purchased, the lambs were about 3.5 months of age and had a mean weight of 29.3 kg w i t h a range of 26.8 to 30.9 kg. The animals were housed indoors i n group pens u n t i l two weeks before the s t a r t of the t r i a l when they were placed i n the metabolism cages. While housed i n the pens they were fed a growing r a t i o n and were t r e a t e d w i t h and a n t h e l m i n t i c wormed, given a c l o s t r i d i a l i n n o c u l a t i o n , t r e a t e d f o r sheep keds and given an i n j e c t i o n of selenium and v i t a m i n E. There were no h e a l t h problems or problems w i t h animals r e f u s i n g feed over the e n t i r e t r i a l p e r i o d . 4.1.5. ANALYTICAL PROCEDURES Lambs were weighed at the end of each p e r i o d . Feed, feces and o r t s were analayzed f o r CP using the macro-Kjehdahl technique (AOAC, 1980) w i t h copper as a c a t a l y s t . The AD and ND f i b r e techniques of Goering and Van Soest (1970) were used w i t h the e x c l u s i o n of d e c a l i n and sodium sulphate from the reagents. Dry matter determinations were done as o u t l i n e d i n S e c t i o n 3.1.1. The composition of the forage mixes f o r c l o v e r and grass content i s determined by s e l e c t i n g 3 f l a k e s from a b a l e of each feed and trimming a 23cm x 23cm s e c t i o n from the middle of each f l a k e . Care i s taken to ensure the i n t e g r i t y of t h i s subsample and the grass and legume components were separated by hand. Once separated the components were d r i e d f o r 48 hours at 45°C and weighed. The mean f o r each treatment combination was then determined and t h i s represented the r e l a t i v e l e v e l s of grass and legume f o r the s i x treatment combinations. In order to i n t e g r a t e y i e l d w i t h the Feeding T r i a l r e s u l t s CP Y i e l d DE Y i e l d were c a l c u l a t e d as o u t l i n e d i n S e c t i o n 3.1.4. 4.2 RESULTS The n u t r i e n t composition of the hay mixes was shown i n Table 4.2. The dry matter l e v e l s ranged from 86.3 to 88.9%. Crude p r o t e i n v a r i e d l i t t l e between hay mixes w i t h EM l e v e l s ranging from 11.4 to 11.5% and LM l e v e l s from 11.9 to 12.7%. S i m i l a r i t y , ADF and NDF l e v e l s v a r i e d l i t t l e w i t h a range of 34.5 to 37.8% ADF and 48.5 to 54.9% NDF f o r EM, and 38.2 to 41.7% ADF and 51.4 to 52.6% NDF f o r LM r e s p e c t i v e l y . D i g e s t i b l e energy (DE) l e v e l s were highest f o r the EM ranging from 2.42 to 2.60 Mcal/kg and lowest f o r the LM mix ranging from 2.24 to 2.42 Mcal/kg. There was a continuous increase i n the l e v e l of the legume component i n the EM mix from 48 to 57 to 74% f o r EB, MB and FB r e s p e c t i v e l y w i t h a concurrent drop i n the percent grass i n the mix (Table 4.3). However, the legume and grass l e v e l s i n the LM mix were r e l a t i v e l y s t a b l e ranging from 83 to 91% f o r the legume and 9 to 17% f o r Table 4.2 N u t r i e n t Composition of Hay Mixes (Dry Matter B a s i s ) . NUTRIENT Crude ADF NDF DE P r o t e i n Hay Mix (Z) (%) (%) (Mcal/kg) E a r l y M a t u r i n g ( E M ) + + E a r l y Bloom(EB) 1' Mid Bloom (MB) F u l l Bloom (FB) Late Maturing (LM) , [ , ( E a r l y Bloom(EB) Mid Bloom(MB) F u l l Bloom(FB) 11.5 11.5 11.4 12.7 11.9 11.9 37.8 34.5 36.9 38.2 38.5 41.7 54.9 48.5 50.9 52.6 51.4 52.3 2.61 2.68 2.63 2.60 2.59 2.52 + ADF = A c i d Detergent F i b r e , NDF = N e u t r a l Detergent F i b r e DE = D i g e s t i b l e Energy Estimate (Mathison et a l . , 1982) ++ EM = a l s i k e c l o v e r - timothy - bromegrass hay mix 1t EB,MB,FB = 102,50%,100% of bloom of the legume component of the forage mix. 1(11 LM = red c l o v e r - timothy hay mix. Table 4.3 P r o p o r t i o n of Grass and Legume i n Each Hay Mix Component Legume Grass Hay Mix (%) (X) E a r l y Maturing(EM) + + E a r l y Bloom(EB) 48 52 Mid Bloom(MB) 57 43 F u l l Bloom(FB) 74 26 Late Maturing (LM)^' E a r l y Bloom(EB) 83 17 Mid Bloom(MB) 91 9 F u l l Bloom(FB) 89 11 + EM = a l s i k e c l o v e r - timothy - bromegrass mix. ++ EB, MB, FB = 10%, 50%, 100% of bloom of the legume component of the forage mix. 1! LM = red c l o v e r - timothy mix. the grass components r e s p e c t i v e l y . Table 4.4 shows the feed i n t a k e r e s u l t s of the e a r l y maturing (EM) forage mix compared w i t h the l a t e maturing (LM) forage mix. There i s a s i g n i f i c a n t d i f f e r e n c e (P ̂ 0 . 0 1 ) i n in t a k e f o r a l l f a c t o r s measured except a c i d detergent f i b r e i n t a k e (ADFI) w i t h the EM mix being more r e a d i l y consumed than the LM mix. DMI f o r the EM mix was 80.2 ± 1.02g/BW°''75 and f o r the LM forage mix was 72.2 ± 1.02g/BW°' 7 5 (P^O.01). S i m i l a r i l y , there was a s i g n i f i c a n t d i f f e r e n c e (P^O.01) between the EM and LM forage mixes f o r a l l d i g e s t i b i l i t y f a c t o r s measured (Table 4.5). DMD f o r the EM mix was 64.9±0.43% versus 61.2+0.43% f o r the LM mix. There was a s i g n i f i c a n t d i f f e r e n c e between harvests f o r DOMI ( P ^ O . 0 1 ) and CPI ( P ^ O . 0 1 ) but 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 harvests f o r ADFI, NDFI or DMI (P>0.05) (Table 4.6). There were 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 between harvests f o r a l l f a c t o r s measured w i t h l e v e l s of 63.5%, 64.4% and 61.1% f o r DMD; 65.4, 65.3 and 61.6% f o r CPD; 54.1, 51.7 and 49.9% f o r ADFD and 57.4, 54.3 and 51.2% f o r NDFD (P^O.01) f o r the EB, MB and FB harvests r e s p e c t i v e l y (Table 4.7). The Forage Mix X Harvest i n t e r a c t i o n was s i g n i f i c a n t f o r DOMI and CPI (P^0.05) but not f o r DMI, ADFI, NDFI, DMD, CPD, ADFD and NDFD (P>0.05). The e f f e c t s due to animal were s i g n i f i c a n t f o r a l l i n t a k e f a c t o r s (P^IO.OI) but not f o r any d i g e s t i b i l i t y f a c t o r except ADFD ( P > 0 . 0 5 ) . S i m i l a r i l y , the e f f e c t s due to p e r i o d were s i g n i f i c a n t f o r a l l intak e f a c t o r s (DMI, DOMI, CPI (p^0.05 ); ADFI, NDFI ( p ^ O . O l ) ) but not f o r any of the d i g e s t i b i l i t y f a c t o r s (P>0.05). TABLE 4.4 Means of Intake Parameters f o r E a r l y Maturing and Late Maturing Forage Mixes. DMI DOMI CPI ADFI NDFI Hay Mix (g/BW°' 7 5) (g/BW°* 7 5) (g/day) (g/day) (g/day) EM + + 80.2 a 4 8 . l a 158 a 485 a 685 a LM1[ 72.7 b 41. l b 144 b 477 a 640 b SEM 1.02 0.66 2.77 7.98 9.81 + DMI = Dry Matter Intake;, DOMI = D i g e s t i b l e Organic Matter Intake; CPI = Crude P r o t e i n Intake; ADFI = A c i d Detergent F i b r e Intake; NDFI = N e u t r a l Detergent F i b r e Intake; ++ EM Forage Mix = a l s i k e c l o v e r , timothy, and bromegrass. 11 LM Forage Mix = red c l o v e r and timothy. 1(11 SEM = Standard E r r o r of the Mean a,b Means w i t h i n columns w i t h d i f f e r e n t s u p e r s c r i p t s are d i f f e r e n t ( P ^ 0 . 0 5 ) . TABLE 4.5 Means of D i g e s t i b i l i t y Parameters For E a r l y Maturing and Late Maturing Forage Mixes. DMD+ CPD ADFD NDFD Hay Mix (%) (%) (%) (%) EM + + 64.9 a 6 6 . l a 54.7 a 57.3 a LM11 61.2 b 62.0 b 4 9 . l b 51.3 b SEM™ 0.43 0.54 0.62 0.72 + DMD = Dry Matter D i g e s t i b i l i t y ; CPD = Crude P r o t e i n D i g e s t i b l i t y ; . ADFD = A c i d Detergent f i b r e D i g e s t i b i l i t y ; NDFD = N e u t r a l Detergent F i b r e D i g e s t i b l i t y . ++ EM Forage Mix = a l s i k e c l o v e r , timothy, and bromegrass. II LM Forage Mix = red c l o v e r and timothy. SEM = Standard E r r o r of the Mean a,b Means w i t h i n columns w i t h d i f f e r e n t s u p e r s c r i p t s are d i f f e r e n t (P<.0.05). TABLE 4.6 Means of Intake Bloom Harvests. Parameters f o r E a r l y , Mid and F u l l DMI + DOMI CPI ADFI NDFI Harvest (g/BW 0' 7 5) (g/BW 0' 7 5) (g/day) (g/day) (g/day) , ++ E a r l y Bloom 76.2 a 4 5 . l a 157 a 482 a 682 a Mid Bloom 78.6 a 46.6 a 154 a 479 a 656 a F u l l Bloom 74.4 a 42.2 b 140 b 4 8 1 a 649 a SEM11 1.25 0.81 3.40 9.77 12.01 + DMI = Dry Matter Intake; DOMI = D i g e s t i b l e Organic Matter Intake; CPI = Crude P r o t e i n Intake; ADFI = A c i d Detergent F i b r e Intake; NDFI = N e u t r a l Detergent F i b r e Intake. ++ E a r l y , Mid and F u l l Bloom = 10%, 50% and 100% of bloom of the legume component of the forage. 11 SEM = Standard E r r o r of the Mean a,b Means w i t h i n columns w i t h d i f f e r e n t s u p e r s c r i p t s are d i f f e r e n t ( P ^ 0 . 0 5 ) . TABLE 4.7 Means of D i g e s t i b i l i t y Parameters f o r E a r l y , Mid and F u l l Bloom Harvests. DMD+ CPD ADFD NDFD Harvest (%) (X) (%) (%) E a r l y + + Bloom 63.5 a 65.4 a 54. l a 57.3 a Mid Bloom 64.4 a 65.3 a 51.7 b 54.3 b F u l l Bloom 61. l b 61.6 b 49.9 b 51.2 C SEM1' 0.53 0.66 0.76 0.88 + DMD = Dry Matter D i g e s t i b i l i t y ; CPD = Crude P r o t e i n D i g e s t i b l i t y ; ADFD = A c i d Detergent f i b r e D i g e s t i b i l i t y ; NDFD = N e u t r a l Detergent F i b r e D i g e s t i b l i t y . ++ E a r l y , Mid and F u l l Bloom = 10%, 50% and 100% of bloom of the legume component of the forage. 11 SEM = Standard E r r o r of the Mean a,b Means w i t h i n columns w i t h d i f f e r e n t s u p e r s c r i p t s are d i f f e r e n t ( P ^ 0 . 0 5 ) . Even though there were only s i x data p o i n t s , the RSQUARE procedure i s used to determine i f a r e g r e s s i o n equation could be developed to p r e d i c t DMI, DOMI or DMD (Table 4.8). The r e s u l t s i n d i c a t e that the c o d f f i c i e n t s of determination based upon a s i n g l e f a c t o r would vary l i t t l e from those based on m u l t i p l e f a c t o r s . Thus, there would be l i t t l e improvement i n p r e d i c t a b i l i t y w i t h equations based on these r e s u l t s i f more than one f a c t o r was inc l u d e d i n the r e g r e s s i o n equation. O v e r a l l , there were no c o e f f i c i e n t s of determination s u f f i c i e n t l y l a r g e to warrent developing a p r e d i c t i v e equation. The DE values used to estimate DEY i n Table 4.9 were c a l c u l a t e d from the ADF values shown i n Table 4.1. Only 6 values f o r each parameter could be estimated and t h e r e f o r e there were i n s u f f i c i e n t degrees of freedom to analyse the c a l c u l a t e d values u s i n g an ANOVA procedure. However, when the CPY and DEY values were examined the LM mix had greater DE and CP y i e l d s than the LM mix. As w e l l , each of the DE and CP y i e l d s increased from the EB to the FB harvest. Table 4.8 C o e f f i c i e n t s of Determination f o r Simple and M u l t i p l e F a c t o r Models Dependent V a r i a b l e R-Square Values Number of Fact o r s i n Model Facto r i n Model DMI1t DOMI DMD 1 1 1 CP™ ADF NDF 0.020 0.109 0.143 0.034 0.184 0.195 0.038 0.195 0.460 2 2 2 CP ADF CP NDF ADF NDF 0.109 0.144 0.145 0.188 0.195 0.211 0.199 0.470 0.487 3 CP ADF NDF 0.145 0.211 0.498 11 DMI = Dry Matter Intake, DOMI = D i g e s t i b l e Organic Matter Intake DMD = Dry Matter D i g e s t i b i l i t y . 1111 CP = Crude P r o t e i n , ADF = A c i d Detergent F i b r e , NDF = N e u t r a l Detergent F i b r e Table 4.9 Hay Mix, Harvest Date and Y i e l d of Test Forages Hay Mix CP Y i e l d (T/ha) Y i e l d , (Meals x 10 /ha) ++ E a r l y Maturing (EM)* E a r l y Bloom (EB) Mid Bloom (MB) F u l l Bloom (FB) Late Maturing (LM) E a r l y Bloom (EB) Mid Bloom (MB) F u l l Bloom (FB) J u l y 9 J u l y 15 J u l y 22 J u l y 22 J u l y 30 August 8 5.6 7.6 9.4 9.2 9.9 11.0 + EM = a l s i k e c l o v e r - timothy - bromegrass forage mix. ++ EB,MB,LB = 102,502 1002 of bloom of the legume component of the forage mix. It Estimate f o r EM-EB based on known weight of a i r dry m a t e r i a l removed from 0.1 ha. 1111 LM = red c l o v e r timothy forage mix. 4.3 DISCUSSION 4.3.1 INTAKE AND DIGESTIBILITY According to Van Soest (1982) NDF was b e t t e r r e l a t e d to i n t a k e and ADF to d i g e s t i b i l i t y . Therefore i t should f o l l o w t h a t , s i n c e the NDF l e v e l of EM was lower than the NDF l e v e l of LM the EM mix would be consumed i n g r e a t e r amounts than the LM mix. While t h i s was the case the d i f f e r e n c e between EM and LM NDF l e v e l s was s m a l l (51.8 vs 52.1% r e s p e c t i v e l y ) and would not account f o r the d i f f e r e n c e i n DMI. The d i f f e r e n c e i n ADF l e v e l s between EM and LM (39.7 vs 42.1% r e s p e c t i v e l y ) was l a r g e r than the d i f f e r e n c e i n NDF l e v e l s and, as i n d i c a t e d by Van Soest (1982), e x p l a i n s the 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 between the two mixes. D i g e s t i b i l i t y may a l s o e x p l a i n the d i f f e r e n c e i n DMI obtained between the two mixes. I t has been reported ( B l a x t e r et a l . , 1961; Bines, 1971) that i n t a k e of forages w i t h d i g e s t i b i l i t i e s g r e a t e r than 66% was l i m i t e d by the animal's requirement f o r energy and i n t a k e of forages w i t h d i g e s t i b i l i t i e s of l e s s than 66% was l i m i t e d by rumen f i l l . I n a d d i t i o n , r e t e n t i o n time i n the rumen incr e a s e s and d i l u t i o n r a t e decreases. The d i g e s t i b i l i t y of the EM mix was only 1 percentage p o i n t below 66% w h i l e the LM mix i s 5 percentage p o i n t s lower. This i n d i c a t e s that r e t e n t i o n time was increased and d i l u t i o n r a t e decreased i n LM r e l a t i v e to EM and t h e r e f o r e passage r a t e of the forage was slowed and the i n t a k e of LM reduced. Since the i n t a k e of dry matter was greater f o r EM than LM i t would f o l l o w then, that CPI, NDFI AND ADFI would a l s o be s i g n i f i c a n t l y g r e a t e r . This was true i n a l l cases except ADFI and i n d i c a t e d that the animal consumed each forage to the p o i n t where i n t a k e was l i m i t e d by d i g e s t i b i l i t y since the i n t a k e of ADF (the f i b r e f r a c t i o n r e l a t i n g best w i t h d i g e s t i b i l i t y ) was not d i f f e r e n t between mixes. The d i f f e r e n c e s i n the d i g e s t i b i l i t y of the CP, ADF and NDF f r a c t i o n s would r e l a t e to the increased energy a v a i l a b l e from the EM mix a l l o w i n g f o r grea t e r m i c r o b i a l a c t i v i t y and th e r e f o r e greater d i g e s t i o n of the c e l l w a l l component of the p l a n t . This would r e s u l t from a great e r percentage of s o l u b l e c e l l contents and a l e s s e r percentage of i n d i g e s t i b l e f i b r o u s m a t e r i a l (Van Soest, 1982). Since there were s i g n i f i c a n t d i f f e r e n c e s between EM and LM f o r both i n t a k e and d i g e s t i b i l i t y i t would a l s o f o l l o w that DOMI would be d i f f e r e n t as a r e s u l t of the combination of f a c t o r s j u s t d i s c u s s e d . There was no s i g n i f i c a n t d i f f e r e n c e i n DMI between the E a r l y (EB), Mid (MB) and F u l l Bloom (FB) ha r v e s t s . This r e s u l t would be expected based on the sm a l l v a r i a t i o n i n NDF l e v e l s o c c u r r i n g between harvests (38.0,36.5 and 39.3% r e s p e c t i v e l y ) . Again, as expected, ADFI and NDFI l e v e l s were not s i g n i f i c a n t l y d i f f e r e n t , however, CPI l e v e l s were lower f o r FB than f o r EM and MB ha r v e s t s . This may be due to the s l i g h t l y lower DMI f o r FB coupled w i t h a s l i g h t l y lower CP l e v e l r e l a t i v e to EM and MB (12.1, 11.7 and 11.65% r e s p e c t i v e l y ) . The DMD r e s u l t s f o r EB, MB and FB c l o s e l y p a r a l l e l the ADF l e v e l s (38.0, 36.5 and 39.3% r e s p e c t i v e l y ) obtained i n each harvest i n that the FB-ADF l e v e l s were higher w h i l e DMD was lower. As w e l l , CPD, ADFD and NDFD l e v e l s f o r FB were lower than EB and MB i n d i c a t i n g t h a t , as expected, the FB m a t e r i a l was of lower n u t r i t i o n a l value than the e a r l i e r harvested m a t e r i a l . Since each feed was consumed to the poin t where f i b r e i n t a k e s were equal even though f i b r e l e v e l s i n the feed were d i f f e r e n t , energy values must impact on d i g e s t i b i l i t y s i n c e d i g e s t i b l e energy (DE) estimates were lowest i n the FB harvest (2.35 v s . 2.42 and 2.49 Mcals/kg f o r FB, EB and MB r e s p e c t i v e l y ) as p r e d i c t e d from ADF va l u e s . DOMI was s i g n i f i c a n t l y higher f o r EB and MB than f o r FB harvests due to a combination of higher i n t a k e s and d i g e s t i b i l i t i e s f o r the e a r l i e r cut h a r v e s t s . O v e r a l l , these r e s u l t s i n d i c a t e that the EM forage mix harvested at the mid-bloom stage was the best forage based on i n t a k e and d i g e s t i b i l i t y parameters. For the most p a r t , i n t e r a c t i o n s between hay mix and harvest were not s i g n i f i c a n t , however a s i g n i f i c a n t i n t e r a c t i o n i s obtained f o r DOMI and CPI. For DOMI the i n t e r a c t i o n may be explained by the degree of v a r i a t i o n between the values f o r the EM and LM mixes at the FB harvest r e l a t i v e to the values obtained at the EB and MB ha r v e s t s . The values f o r the f i r s t two harvests were much c l o s e r than f o r the l a s t harvest (48.0 v s . 42.2, 42.2 vs 44.2 and 47.5 v s . 37.0 g/BW 0 , 7 5 f o r the EM and LM mixes harvested at the EB, MB and FB stages r e s p e c t i v e l y ) . The s i t u a t i o n f o r CPI was the same w i t h the EM and LM values being 160 v s . 155 ,157 v s . 151 and 157 v s . 125 g f o r the EM and LM mixes harvested at the EM, MB and FB stages r e s p e c t i v e l y . Thus both i n t e r a c t i o n s were s i g n i f i c a n t due to l a r g e r d i f f e r e n c e s i n the values of the l a s t harvest r e l a t i v e to the e a r l i e r h a r v e s t s , not due to one mix having a higher v a l u e f o r a determination at one harvest date and the other mix having a higher value a t another date. With the exception of ADFD there was no e f f e c t on any d i g e s t i b i l i t y d etermination due to the t e s t animal or the t e s t p e r i o d . However, the e f f e c t of t e s t animal and t e s t p e r i o d was s i g n i f i c a n t f o r a l l i n t a k e parameters. There was a 13% d i f f e r e n c e i n the l i v e weight of the l a r g e s t and smallest sheep at the time of purchase and t h i s v a r i a t i o n i n s i z e continued through to the end of the t r i a l p e r i o d at which p o i n t there was a range of about 5 kg (or 10%) i n animal l i v e weight between t e s t sheep. Since food consumption inc r e a s e s w i t h i n c r e a s i n g l i v e w e i g h t at a comparable fat n e s s ( M e i j s , 1982) i t would be expected that there would be d i f f e r e n c e s i n i n t a k e between animals at any time during the t r i a l . S i m i l a r i l y , i t would be expected that d i f f e r e n c e s i n in t a k e would occur between t e s t periods because the t e s t animals were s t i l l growing and t h e i r weights increased an average of 9.4 kgs or about 25% of t o t a l body weight from the s t a r t of the t r i a l . Weston and Margan (1979) reported increases i n the in t a k e of sheep on t r i a l between the ages of 24 and 40 weeks (compared w i t h 21 to 39 weeks of age f o r sheep used i n t h i s study) of about 20% of the in t a k e at 24 weeks of age. This l e v e l of v a r i a t i o n i n i n t a k e over the t r i a l p e r i o d would c e r t a i n l y r e s u l t i n an e f f e c t on in t a k e parameters due to p e r i o d . These authors a l s o reported a sm a l l but s i g n i f i c a n t decrease i n the l e v e l of c e l l w a l l c o n s t i t u e n t s digested i n the alimentary t r a c t between the ages of 24 and 40 weeks. While they were not c o n s i d e r i n g d i f f e r e n c e s between animals t h i s e f f e c t must be r e l a t e d to the changing s i z e of the t e s t animals and may e x p l a i n the s i g n i f i c a n t e f f e c t of animal on ADFD sin c e there was a 10% v a r i a t i o n i n animal l i v e w e i g h t . 4.3.2 UNCONTROLLED FACTORS There were two major u n c o n t r o l l e d f a c t o r s t h a t may have had an impact on the outcome of the experiment. These were: 1) the p r e c i p i t a t i o n that was re c e i v e d by the EM-EB, EM-FB and LM-EB forages, and 2) the r e l a t i v e l e v e l of grasses and c l o v e r s i n each forage mix and harvest. While no measurements were taken of the a c t u a l amounts of r a i n f a l l i n g on the s i t e there were at l e a s t s e v e r a l m i l l i m e t e r s of p r e c i p i t a t i o n , u s u a l l y f a l l i n g l a t e r i n the dr y i n g p e r i o d . Anderson (1976) i n d i c a t e d that a r e l a t i v e l y heavy r a i n immediately a f t e r c u t t i n g w i l l do minimal damage i f f o l l o w e d by favourable weather whereas the same amount of r a i n on dry hay can cause heavy n u t r i e n t l o s s e s . Both C o l l i n s (1983, 1985) and Fonnesbeck et_ al^. (1982) reported that w e t t i n g d i d not change the percentage of N i n the hay, however there was increased l e a f and o v e r a l l dry matter l o s s e s w i t h the e f f e c t s being g r e a t e r at bud stage than at bloom stage i n red c l o v e r . Fonnesbeck et^ a l . (1982) reported that these dry matter l o s s e s were i n the range of 10% a f t e r 20 mm of r a i n f e l l r e p r e s e n t i n g the s o l u b l e ash, l i p i d and a v a i l a b l e carbohydrate p o r t i o n of the p l a n t . With i n c r e a s i n g amounts of r a i n the percentage of c e l l w a l l increased (Fonnesbeck et_ a l . , 1982) r e s u l t i n g i n increased ADF and NDF l e v e l s ( C o l l i n s 1983, 1985). These observations help e x p l a i n the n u t r i e n t composition of the hay mixes. There was l i t t l e e f f e c t on CP l e v e l due to p r e c i p i t a t i o n (Table 5.7) s i n c e there was l i t t l e d i f f e r e n c e between wetted and r a i n f r e e h a r v e s t s , but r a i n f a l l does appear to have a f f e c t e d ADF and NDF l e v e l s . According to Van Soest (1982) the amount of c e l l w a l l m a t e r i a l should increase w i t h i n c r e a s i n g p l a n t m a t u r i t y . This was evidenced by the increases i n ADF and NDF values between Mid and F u l l Bloom harvests f o r both the e a r l y and l a t e mixes. However, both f i b r e measurements are great e r f o r EB than f o r MB and FB (except f o r ADF i n the LM mix) and si n c e both EB-EM and EB-LM re c e i v e d p r e c i p i t a t i o n t h i s would e x p l a i n t h i s unexpected r e s u l t . The second u n c o n t r o l l e d f a c t o r was the species composition (Table 4.2). The l e v e l of red c l o v e r i n the LM mix was higher than expected f o r a l l h a r v e s t s and the l e v e l of a l s i k e c l o v e r i n the EM mix increased between the EB and FB h a r v e s t s . The l e v e l s of both c l o v e r s were higher than what would be expected when the percentage of each i n the seed mix was considered. C o l l i n s (1985) reported that i n a red clover-smooth bromegrass mixture the red c l o v e r made up about 92% of the t o t a l mixture. McBratney (1981, 1984) a l s o reported s i m i l a r f i n d i n g s w i t h red c l o v e r and grass mixes i n which timothy c o n t r i b u t e d the l e a s t of any of the t e s t grasses to the t o t a l DM y i e l d . The author i n d i c a t e d that t h i s c o n c e n t r a t i o n was about 15% of the y i e l d over s e v e r a l years. Since legumes tend to maintain t h e i r n u t r i t i v e value longer through the growing season than grasses (Van Soest, 1982) and a l f a l f a and red c l o v e r are lower i n c e l l w a l l c o n s t i t u e n t s and d i g e s t i b l e f i b r e and higher i n c e l l s o l u b l e s than p e r e n n i a l ryegrass at s i m i l a r growth stages (Campling, 1984), i t would be expected that high l e v e l s or i n c r e a s i n g l e v e l s of legumes i n the mixture would reduce the d i f f e r e n c e s i n feed value between EB and FB h a r v e s t s . I n combination then, the r a i n f a l l on the EB harvests and the high l e v e l s of legume i n the FB harvests acted to reduce the v a r i a t i o n i n n u t r i e n t l e v e l s between h a r v e s t s . This would p a r t i a l l y e x p l a i n why there was no d i f f e r e n c e i n any in t a k e parameters or i n DMD and CPD between EB and MB harvests even though a d i f f e r e n c e could be expected. 4.3.3 LINEAR AND QUADRATIC REGRESSION ANALYSIS The c o e f f i c i e n t s of determination obtained by r e g r e s s i o n a n a l y s i s were a l l l e s s than 0.5. The highest c o e f f i c i e n t obtained was that f o r es t i m a t i n g DMD from NDF determinations. The r e g r e s s i o n c o e f f i c i e n t s f o r DMD using m u l t i p l e f a c t o r s d i d not increase s i g n i f i c a n t l y . This may be expected s i n c e only s i x data p o i n t s were used i n the a n a l y s i s . Narasimhalu et^ a l . (1982) reported t h a t n e i t h e r NDF nor ADF were c o r r e l a t e d w i t h DMD i n work done on orchardgrass, bromegrass or timothy. Aderibigbe et^ a l . (1982) i n a t r i a l w i t h ryegrasses r e p o r t s there was no r e l a t i o n s h i p between CP and DMI — a r e s u l t s i m i l a r to that obtained i n t h i s t r i a l . The d i f f e r e n c e i n a c t u a l i n t a k e and d i g e s t i b i l i t y r e s u l t s of the Feeding T r i a l and that suggested by the r e s u l t s of the V a r i e t y T r i a l , as discussed i n the previous s e c t i o n , f u r t h e r support the f i n d i n g of r e l a t i v e l y low c o e f f i c i e n t s of determination obtained when r e g r e s s i n g l a b o r a t o r y r e s u l t s upon d i g e s t i b i l i t y parameters. There was s t i l l a great d e a l of v a r i a t i o n to be accounted f o r before the i n t a k e and d i g e s t i b i l i t y of f e e d s t u f f s by ruminants can be p r e d i c t e d . 4.3.4 INTEGRATED RESULTS WITH YIELD When q u a l i t y parameters were i n t e g r a t e d w i t h the y i e l d of the two hay mixes over the three harvests d i f f e r e n t conclusions were reached than when j u s t q u a l i t y parameters were considered. Even though the LM mix i s lower i n i n t a k e and d i g e s t i b i l i t y i t was higher y i e l d i n g . Thus, i n terms of CP and energy produced from a given area of land the LM mix was more productive than the EM mix. When c o n s i d e r i n g the value of a given forage species or mix, y i e l d as w e l l as q u a l i t y must be considered. 4.3.5 COMPARISON WITH VARIETY TRIAL RESULTS The i n t a k e and d i g e s t i b i l i t y r e s u l t s obtained i n the feeding t r i a l between hay mixes vary somewhat from what would be expected based on l a b o r a t o r y r e s u l t s obtained i n the v a r i e t y t r i a l . NDF l e v e l s f o r a l s i k e c l o v e r and red c l o v e r were not s i g n i f i c a n t l y d i f f e r e n t suggesting that the i n t a k e s of the two c l o v e r s would a l s o not be d i f f e r e n t . In terms of d i g e s t i b i l i t y , NBDMD r e s u l t s from the v a r i e t y t r i a l would again suggest no d i f f e r e n c e s between mixes s i n c e there was no s i g n f i c a n t d i f f e r e n c e between red and a l s i k e c l o v e r . With regard to the grass component of each hay mix the r e s u l t s of Seone et a l . (1981b) f o r NBDMD suggested that Toro was more d i g e s t i b l e than Climax (45.4 v s . 35.7% disappearance r e s p e c t i v e l y ) . This agrees w i t h the feeding t r i a l r e s u l t i n that the EM ( c o n t a i n i n g Toro timothy) was more d i g e s t i b l e than the LM mix ( c o n t a i n i n g Climax ti m o t h y ) . However, the l a r g e percentage of legume i n each mix at a l l harvests would l i m i t the v a l i d i t y of t h i s o b s e r v a t i o n . The ADF values obtained i n the V a r i e t y T r i a l a l s o c o n t r a d i c t the r e s u l t s of the feeding t r i a l i n that the l e v e l s f o r a l s i k e c l o v e r (32.2±1.10%) were s i g n i f i c a n t l y greater than f o r the red c l o v e r (30.9±0.65%). This i n d i c a t e s that the red c l o v e r mix should be more d i g e s t i b l e than the a l s i k e c l o v e r mix. Seone et a l . (1981b) found only a 1.7% d i f f e r e n c e i n DMD between Toro and Climax timothy v a r i e t i e s . CHAPTER 5 - GENERAL DISCUSSION AND CONCLUSIONS The experiments conducted i n t h i s study examined s e v e r a l aspects of forage q u a l i t y ( i n terms of animal n u t r i t i o n ) i n c l u d i n g the d i f f e r e n c e s between Type, Species and V a r i e t i e s w i t h i n s p e c i e s ; the d i f f e r e n c e s between years; the d i f f e r e n c e s between two forage mixes; the d i f f e r e n c e s between three harvest dates and the importance of q u a l i t y r e l a t i v e to y i e l d . In g e n e r a l , t h i s study showed that the legumes were of b e t t e r n u t r i t i o n a l q u a l i t y than grasses; that the c l o v e r s were of b e t t e r q u a l i t y than a l f a l f a , and that orchardgrass was of b e t t e r q u a l i t y than timothy. When the n u t r i t i o n a l q u a l i t y of v a r i e t i e s w i t h i n species was examined, only the red c l o v e r v a r i e t i e s (Altaswede, P a c i f i c and Lakeland) showed s i g n i f i c a n t d i f f e r e n c e s . Therefore, there was no d i f f e r e n c e i n q u a l i t y between those a l f a l f a , orchardgrass or timothy v a r i e t i e s examined. Over the 3 study y e a r s , there were d i f f e r e n c e s i n CP and NDF but not i n ADF or NBDMD i n d i c a t i n g there would be a d i f f e r e n c e i n i n t a k e and o v e r a l l q u a l i t y between years but there would be l i t t l e 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 the t e s t forages between years. The r e s u l t s of the Feeding T r i a l showed that the e a r l y maturing mix had higher i n t a k e and d i g e s t i b i l i t y than the l a t e maturing mix. An examination of the species composition revealed that the c l o v e r s made up a major p o r t i o n of each mix and t h e r e f o r e would have had the l a r g e s t e f f e c t on i n t a k e and d i g e s t i b i l i t y . The Feeding T r i a l r e s u l t s are d i f f e r e n t than would be expected based on the r e s u l t s of the v a r i e t y t r i a l . There was no d i f f e r e n c e i n NDF l e v e l s between red and a l s i k e c l o v e r i n the V a r i e t y T r i a l suggesting that i n t a k e s would not be d i f f e r e n t . A l s o , a l s i k e c l o v e r had s i g n i f i c a n t l y higher ADF values than red c l o v e r (although NBDMD values were not d i f f e r e n t ) suggesting that red c l o v e r i s more d i g e s t i b l e than a l s i k e c l o v e r . In the Feeding T r i a l the a l s i k e c l o v e r mix was consumed at g r e a t e r l e v e l s than the red c l o v e r mix w h i l e the red c l o v e r was l e s s d i g e s t i b l e than the a l s i k e c l o v e r . This comparison of r e s u l t s from each t r i a l i l l u s t r a t e s the p o i n t that the l a b o r a t o r y determinations used to p r e d i c t a p a r t i c u l a r feeding parameter s t i l l have great v a r i a b i l i t y a s s o c i a t e d w i t h them. D i f f e r e n c e s were a l s o found i n i n t a k e and d i g e s t i b i l i t y between h a r v e s t s . This was expected s i n c e the p l a n t s mature and l o s e n u t r i t i o n a l v a l u e over the growing season r e s u l t i n g i n a p r o g r e s s i v e drop i n forage q u a l i t y from harvest to h a r v e s t . However, the r e s u l t s of t h i s study were not as expected w i t h the e a r l y bloom harvest being of s i m i l a r q u a l i t y to the mid bloom, both of which were of b e t t e r q u a l i t y than the l a t e bloom harv e s t . Furthermore, NDF and ADF values f o r the e a r l y bloom harvest were as h i g h or higher than the l a t e r h a r v e s t s , contrary to e x p e c t a t i o n s . These r e s u l t s may be explained by two u n c o n t r o l l e d f a c t o r s - p r e c i p i t a t i o n and the l e v e l of legume i n each forage mix. Both f a c t o r s worked to reduce the v a r i a b i l i t y between harvests and p o i n t out that p r e c i p i t a t i o n can have a l a r g e negative e f f e c t on forage q u a l i t y , w h i l e the l e v e l of legume i n the mix ( e s p e c i a l l y i f the p r o p o r t i o n i n c r e a s e s as occurred w i t h the EM mix) can have a l a r g e p o s i t i v e i n f l u e n c e on forage q u a l i t y . However, the f a c t o r w i t h the l a r g e s t v a r i a t i o n , whether d i s c u s s i n g d i f f e r e n c e s between forages, y e a r s , forage mixes, or harvest dates, was y i e l d . In the feeding t r i a l , the l a r g e s t d i f f e r e n c e i n y i e l d was between years due to the d i f f e r e n t growing c o n d i t i o n s o c c u r r i n g i n each of the three years that samples were c o l l e c t e d f o r the v a r i e t y t r i a l . The next l a r g e s t d i f f e r e n c e occurred between d i f f e r e n t species or forage mixes, and the l e a s t d i f f e r e n c e i n y i e l d was between v a r i e t i e s . The one exception was i n the case of red c l o v e r where there was considerable d i f f e r e n c e s i n y i e l d between v a r i e t i e s w i t h Altaswede being the highest and P a c i f i c the lowest y i e l d i n g of a l l the v a r i e t i e s examined. In the v a r i e t y t r i a l , the l a r g e s t d i f f e r e n c e i n y i e l d was between hay mixes and then between h a r v e s t s . Y i e l d and q u a l i t y r e s u l t s may be i n t e g r a t e d by determining the y i e l d of n u t r i e n t s per hectare i n d i c a t i n g the n u t r i e n t production of one forage r e l a t i v e to another. D i f f e r e n t c onclusions were reached i n the of red c l o v e r when both y i e l d and q u a l i t y were considered. Lakeland and P a c i f i c v a r i e t i e s were the highest q u a l i t y forages on t e s t but Lakeland i s the lowest, and P a c i f i c only i n t e r m e d i a t e , i n y i e l d . Altaswede i s of somewhat lower q u a l i t y than the other two red c l o v e r v a r i e t i e s but i s the highest y i e l d i n g forage o v e r a l l . Therefore, the highest q u a l i t y forage produced the l e a s t amount of n u t r i e n t s per hectare w h i l e the somewhat lower q u a l i t y but much higher y i e l d i n g Altaswede v a r i e t y y i e l d e d f a r more n u t r i e n t s per hectare. In a p r a c t i c a l s i t u a t i o n one would have to recommend the lower q u a l i t y but higher y i e l d i n g Altaswede red c l o v e r based on these r e s u l t s . Another more general example of the importance of y i e l d r e l a t i v e to q u a l i t y occurred w i t h orchardgrass and timothy. Orchardgrass was of b e t t e r q u a l i t y than timothy but because timothy produced more forage, the y i e l d of n u t r i e n t s per hectare i s greater f o r timothy. A f i n a l example was from the feeding t r i a l where the EM mix was of b e t t e r q u a l i t y than the LM mix; however, si n c e the LM mix produced higher y i e l d s of forage than the EM mix, the LM mix provided the most n u t r i e n t s per hectare. Thus, unless there was a vast d i f f e r e n c e i n q u a l i t y between two forages, the forage w i t h the hi g h e s t y i e l d w i l l p rovide the beef c a t t l e producer w i t h the most y i e l d of n u t r i e n t s per hectare. One must temper these c o n c l u s i o n s , e s p e c i a l l y those regarding red c l o v e r , w i t h other c o n s i d e r a t i o n s . In the case of red c l o v e r , d r y i n g of the harvested crop i s d i f f i c u l t and t h i s , coupled w i t h the f a c t i t i s a short l i v e d s p e c i e s , i n d i c a t e d that c o n s i d e r a t i o n s other than y i e l d or q u a l i t y must be accounted f o r before forage reccomendations are made. The f o l l o w i n g general c o n c l u s i o n was based on the assumption that the forage crop being harvested was intended as feed f o r beef cows. From t h i s study, i t was concluded that y i e l d was the parameter w i t h the l a r g e s t v a r i a t i o n and t h a t , o v e r a l l , the l a r g e s t v a r i a t i o n s i n y i e l d occur from year to year, the next l a r g e s t between types, then between s p e c i e s , w i t h the l e a s t d i f f e r e n c e i n y i e l d o c c u r r i n g between v a r i e t i e s w i t h i n a s p e c i e s . The d i f f e r e n c e s i n q u a l i t y parameters between types, s p e c i e s , v a r i e t i e s , hay mixes or harvests was not as great and y i e l d w i l l be the most s i g n i f i c a n t f a c t o r determining the production of n u t r i e n t s f o r c a t t l e p r oduction from a given area of lan d . Therefore, when a beef c a t t l e producer was d e c i d i n g on what forage or forage mixture to grow f o r w i n t e r feed, he should s e l e c t the species and v a r i e t y w i t h the highest y i e l d over s e v e r a l years to o b t a i n the most n u t r i e n t s per hectare of land and to reduce the impact of year to year v a r i a t i o n . In a d d i t i o n to s e l e c t i n g the highest y i e l d i n g forages, the producer must harvest h i s crop at the c o r r e c t p h e n o l o g i c a l stage to ob t a i n the highest l e v e l of useable n u t r i e n t s - i n the case of t h i s study, the e a r l y to mid bloom stage of the legume component. CHAPTER 6 RECOMMENDATIONS Several recommendations f o l l o w from t h i s study. Recommendation 1 I t i s recommended that v a r i e t y t e s t i n g continue s i n c e there can be d i f f e r e n c e s i n q u a l i t y and y i e l d parameters between v a r i e t i e s as was shown w i t h red c l o v e r . Recommendation 2 I t i s recommended that management p r a c t i c e s such as harvest procedures, storage methods, f e r t i l i z a t i o n and i r r i g a t i o n techniques a l s o be i n v e s t i g a t e d i n con j u n c t i o n w i t h v a r i e t y t r i a l s . Each of these f a c t o r s can a f f e c t the y i e l d and q u a l i t y of forages harvested f o r l i v e s t o c k . Therefore, forage e v a l u a t i o n i s not complete u n t i l management co n s i d e r a t i o n s are taken i n t o account. Recommendation 3 Research must continue i n order to provide b e t t e r i n t e r p r e t a t i o n of e x i s t i n g forage l a b o r a t o r y e v a l u a t i o n techniques or to provide new techniques so more e f f i c i e n t use of research resources may be made. In p a r t i c u l a r , a technique f o r more a c c u r a t e l y e s t i m a t i n g feed i n t a k e i s needed. 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Res. 19:41-46. r APPENDIX 1 CLIMATE OF THE ENGEN AREA Climate Fac t o r Month T o t a l For Growing Year May June J u l y August Season Sunshine (Hours) 1981 1982 1983 238.3 248.0 272.3 240.2 363.0 147.8 317.3 236.6 193.0 304.2 236.4 251.1 864.7 1084.0 864.2 P r e c i p i t a t i o n (mm) 1981 1982 1983 36.0 25.7 13.3 56.7 14.9 67.5 22.4 70.8 86.1 18.2 57.6 40.8 133.3 169.0 207.7 Temperature (°C) 1981 1982 1983 11.6 9.5 12.5 11.6 17.3 12.9 16.9 16.8 15.3 17.4 14.4 15.2 GGD™ 1981 1982 1983 205 140 233 198 369 237 369 366 319 384 291 316 1156 1166 1105 11 Temperature and p r e c i p i t a t i o n data are from Vanderhoof and sunshine data are from For t St.James. UK GGD = Growing Degree Days (estimated from the monthly mean temperature).

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