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UBC Theses and Dissertations

Evaluation of the silage additive nutrolac sila-aid Zürcher, Philipp 1979

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EVALUATION OF THE SILAGE ADDITIVE NUTROLAC SILA-AID by PHILIPP ZURCHER D i p l . Ing.-Agr. ETH 1977 Swiss F e d e r a l I n s t i t u t e of Technology A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES Department of 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 June, 1979 © P h i l i p p Ziircher, 1979 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 m e n t o f the r e q u i r e m e n t s f o r an advanced degree a t the U n i v e r s i t y o f B r i t i s h C o l u m b i a , I agree t h a t 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 r e f e r e n c e and s t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f 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 g r a n t e d by the Head o f my Department o r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department o f Animal Science The U n i v e r s i t y o f B r i t i s h Columbia 2075 Wesbrook P l a c e V a n c o u v e r , Canada V6T 1W5 June 7, 1979 ABSTRACT Two s i l a g e s were prepared from mature orchardgrass e n s i l e d at 19% dry matter. The a d d i t i v e NutroLac S i l a - A i d , c o n t a i n i n g a dry culture, o f l a c t o b a c i l l i , was added to one s i l a g e at a r a t e of 0.5 kg per tonne of f r e s h herbage, the other s i l a g e remained untreated. A wooden stave s i l o o f 40-tonne c a p a c i t y was f i l l e d w ith each s i l a g e . S i l a g e e f f l u e n t was c o l l e c t e d d a i l y f o r 30 days and the s i l a g e temperature was recorded d a i l y f o r 2.5 months. These two s i l a g e s comprised the only forage i n a two-period c r o s s o v e r d e s i g n f e e d i n g t r i a l . The s i l a g e s were fed ad l i b i t u m (10% feed r e f u s a l ) and g r a i n was fed at a r a t e of .1 kg per 3.5 kg milk y i e l d . Twelve H o l s t e i n cows i n e a r l y t o mid l a c t a t i o n were sub-d i v i d e d i n two groups and a l l o c a t e d t o the t r e a t e d or u n t r e a t e d s i l a g e . The cows were fed the assigned forage f o r a 7-day adjustment p e r i o d and a 7-week experimental p e r i o d . The t r e a t -ments were r e v e r s e d d u r i n g a 7-day change-over p e r i o d and the a l t e r n a t e forage fed f o r a f u r t h e r 6 weeks. Three cows from each group were assig n e d to a 7-day d i g e s t i o n t r i a l f o r t o t a l c o l l e c t i o n o f feces and u r i n e d u r i n g the second l a s t week of each experimental p e r i o d . The herbage e n s i l e d had the same composition f o r both s i l o s , the dry matter and p r o t e i n contents being 19.0 and 14.4% r e s p e c t i v e l y . The t r e a t e d s i l a g e l o s t almost twice as much e f f l u e n t compared to the c o n t r o l . Dry matter and p r o t e i n l o s s accounted f o r 2.5 and 4.2% of the e n s i l e d dry matter and p r o t e i n i n the t r e a t e d s i l a g e and 1.5 and 2.3% i n the c o n t r o l s i l a g e . Peak s i l a g e temperatures of 30.3 and 29.1°C f o r t r e a t e d and u n t r e a t e d s i l a g e were recorded on the n i n t h day a f t e r e n s i l i n g . The r e s u l t i n g s i l a g e had a dry matter and p r o t e i n content of 22.8 and 13.2% (treated) and 23.8 and 13.0% ( u n t r e a t 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 (P^.05) between the two treatments w i t h regards to i n t a k e , body weight change and milk p r o d u c t i o n . On the average the cows consumed 10.1 kg forage and 8.0 kg g r a i n on a dry matter b a s i s and y i e l d e d 2 28.0 kg m i l k c o n t a i n i n g 3.2% f a t . The animals f e d NutroLac s i l a g e gained an average of 3.7 kg per p e r i o d whereas the cows on c o n t r o l s i l a g e l o s t 5.6 kg over the same time. The rumen pH and the a c e t a t e / p r o p i o n a t e r a t i o of the ruminal f l u i d was the same f o r both treatments, the v a l u e s being 6.6 and 2.4. The apparent dry matter d i g e s t i b i l i t y of the t o t a l r a t i o n was s i g n i f i c a n t l y higher (P«.05) f o r the c o n t r o l s i l a g e (70.7%) compared to the t r e a t e d (69.1). The d i g e s t i b i l i t y of o r g a n i c matter and p r o t e i n was not d i f f e r e n t (P>.05) between t r e a t -ments, the average being 7 3.3 and 74.4%. The r e s u l t s from the present experiment tended to be i n favour of the c o n t r o l s i l a g e and i n d i c a t e d t h a t t h e r e was no advantage, and perhaps even a disadvantage, i n terms of dry matter d i g e s t i b i l i t y and i n c r e a s e d e n s i l i n g l o s s e s when NutroLac was added to the grass at e n s i l i n g time. - i v -TABLE OF CONTENTS Page A b s t r a c t i i Table of Contents i v L i s t of Tables v i L i s t o f F i g u r e s v i i i L i s t of Appendix Tables i x Acknowledgements x 1. INTRODUCTION 1 2. LITERATURE SURVEY 3 3. MATERIALS AND METHODS 14 3.1. F i e l d s 14 3.2. • Forage 14 3.3. S i l o s 15 3.4. E f f l u e n t and s i l a g e temperature 16 3.5. S i l a g e IV 3.6. Animals 18 3.7. D i g e s t i b i l i t y t r i a l 21 3.8. Experimental design and s t a t i s t i c a l a n a l y s i s 24 4. RESULTS 2 6 4.1. Feeds 26 4.1.1. Forage i n 2 6 4.1.2. S i l a g e out 27 4.1.3. Comparison of s i l a g e and weigh-back 2 9 4.1.4. G r a i n mixture 30 - v -Page 4.1.5. Degree of p r e s e r v a t i o n 31 4.2. E f f l u e n t l o s s and s i l a g e temperature . . . 32 4.2.1. S i l a g e e f f l u e n t 32 4.2.2. S i l a g e temperature 38 4.3. Feeding t r i a l 40 4.3.1. Intake 40 4.3.2. Body weight change 44 4.3.3. M i l k y i e l d and composition . . . 45 4.3.4. Rumen pH and VFA 47 4.4. D i g e s t i b i l i t y t r i a l 49 4.4.1. Intake and milk y i e l d 49 4.4.2. Feces and u r i n e 50 4.4.3. Apparent d i g e s t i b i l i t y values . . 51 4.5. Comparison between n u t r i e n t i n t a k e and requirement 5 3 5. DISCUSSION , , 55 5.1. Forage composition and chemical determi^-n a t i o n 55 5.2. S i l a g e e f f l u e n t and temperature 61 5.3. Feeding and d i g e s t i b i l i t y t r i a l 65 6 . SUMMARY AND CONCLUSION 1 . . 70 7. BIBLIOGRAPHY 72 8. APPENDIX „ 80 - v i -LIST OF TABLES Table Page 1« Age, weight and l a c t a t i o n of the animals on : experiment 19 2 L o c a t i o n and amount of forage and dry matter harvested on d i f f e r e n t days ' 26 3 Composition o f the forages e n s i l e d 27 4, Composition o f the s i l a g e s and c o n c e n t r a t e . . . . . 2 8 5 Comparison between oven and toluene dry matter . . . 29 6 I n g r e d i e n t s of c o n c e n t r a t e mixture 30 7 Percent r e c o v e r i e s of feed components i n e f f l u e n t and s i l a g e (NutroLac S i l a g e ) 31 8 Percent r e c o v e r i e s of feed components i n e f f l u e n t and s i l a g e ( C o n t r o l S i l a g e ) 31 9 E f f l u e n t composition and t o t a l l o s s d u r i n g the 30-day c o l l e c t i o n p e r i o d 33 10 C o r r e l a t i o n s between e f f l u e n t parameters (NutroLac s i l a g e , 30 p a i r e d o b s e r v a t i o n s ) 36 11 C o r r e l a t i o n s between e f f l u e n t parameters (C o n t r o l s i l a g e , 30 p a i r e d o b s e r v a t i o n s ) 36 12 E f f e c t of treatment on i n t a k e , body weight change and m i l k performance 41 13 E f f e c t of p e r i o d on i n t a k e , body weight change and m i l k performance and o v e r a l l mean 42 14 Rumen pH and p r o p o r t i o n of ruminal v o l a t i l e f a t t y a c i d s i n molar percents . . . ..: 48 15 Intake and m i l k p r o d u c t i o n d u r i n g d i g e s t i b i l i t y ,. . 49 16 Amount and composition of feces 50 17 Dry matter and p r o t e i n l o s s i n feces and amount and 51 composition of u r i n e 18 E f f e c t of treatment on apparent d i g e s t i b i l i t y v alues 52 - v i i -Table Page 19 Composition o f the average d a i l y feed . . . . . . . 53 20 N u t r i e n t i n t a k e and requirements . . 54 - v i i i -LIST OF FIGURES F i g u r e Page 1 E f f e c t of treatment on d a i l y e f f l u e n t l o s s 32 2 D a i l y l o s s of dry matter v i a e f f l u e n t 34 3 D a i l y l o s s o f p r o t e i n v i a e f f l u e n t 35 4 Change i n e f f l u e n t DM with time 37 5 Treatment and s i l a g e temperature 38 6 E f f e c t of treatment on forage i n t a k e 4 3 7 Average forage and t o t a l DM i n t a k e of a l l cows . . . 44 8 E f f e c t o f treatment on milk p r o d u c t i o n 46 9 D e c l i n e o f m i l k y i e l d and FCM over time ( l i n e a r r e g r e s s i o n s ) 47 - i x -LIST OF APPENDIX TABLES Table Page 1 Feed i n t a k e , m i l k y i e l d and body weight change as an average per cow and p e r i o d 8 0 - x -ACKNOWLEDGEMENTS The a u t h o r i s i n d e b t e d t o D r . J . A. S h e l f o r d , D e p a r t m e n t o f A n i m a l S c i e n c e U.B.C., and D r . L. J . F i s h e r , R e s e a r c h S t a t i o n A g a s s i z , f o r t h e i r g u i d a n c e and h e l p t h r o u g h h i s s t u d i e s . He a l s o w i s h e s t o a c k n o w l e d g e t h e h e l p o f D r . R. G. P e t e r s o n a n d M r s . M. S t r i k e r f o r a s s i s t a n c e i n t h e a n a l y s i s o f t h e d a t a . T h a n k s a r e a l s o due t o t h e F a c u l t y o f G r a d u a t e S t u d i e s f o r t h e U.B.C. G r a d u a t e F e l l o w s h i p w h i c h made i t p o s s i b l e t o s t u d y i n C a n a d a . The a u t h o r w o u l d a l s o l i k e t o a c k n o w l e d g e t h e s e r v i c e s o f t h e s t a f f a t t h e R e s e a r c h S t a t i o n f o r p r e p a r i n g t h e s i l a g e , k e e p i n g c a r e o f t h e a n i m a l s and a s s i s t i n g i n c h e m i c a l a n a l y s e s . Thank y o u a l s o t o t h e B r i t i s h C o l u m b i a M i n i s t r y o f A g r i c u l t u r e , B u r n a b y f o r t h e a n a l y s i s o f m i l k s a m p l e s . F i n a l l y t h a n k y o u t o S t a r - L a b s I n c . R.R. 1, High w a y 3 1 , S o u t h C l a r k s d a l e , M i s s o u r i USA f o r p r o v i d i n g t h e s i l a g e a d d i t i v e N u t r o L a c S i l a - A i d . - 1 -1. INTRODUCTION The p r o d u c t i o n o f s i l a g e h a s b e e n i n c r e a s i n g r a p i d l y i n t h e l a s t 2 0 y e a r s and i s c o n s i d e r e d an i m p o r t a n t s o u r c e o f f o r a g e n u t r i e n t s f o r r u m i n a n t s . The s t o r a g e o f m a t e r i a l s i n a s i l o , e i t h e r as g r a i n o r a s a g r e e n c r o p , h a s b e e n common p r a c t i c e f o r many h u n d r e d s o f y e a r s . The p r o d u c t i o n o f p o o r q u a l i t y s i l a g e i s a w i d e s p r e a d p r o b l e m a nd t h e r e s u l t a n t n u t r i -e n t l o s s e s a r e o f a l a r g e m a g n i t u d e . The u s e o f a d d i t i v e s t o p r o m o t e s i l a g e f e r m e n t a t i o n a n d t o e n s u r e a h i g h q u a l i t y f e e d h a s b e e n p r a c t i c e d a l m o s t as l o n g as s i l a g e m a k i n g . A c i d s h a v e b e e n u s e d s u c c e s s f u l l y a s a d d i t i v e s i n t h e s i l a g e m a k i n g p r o c e s s , t h e mos t w i d e l y u s e d b e i n g f o r m i c ( L u s k , 1 9 7 8 ; W a l d o , 1 9 7 8 ) . However, t h e a p p l i c a t i o n o f a c i d may r e s u l t i n i n j u r y t o p e r s o n s h a n d l i n g i t a n d f u r t h e r m o r e c a u s e s m a c h i n e r y t o c o r r o d e . W i t h t h e u s e o f p o w d e r e d a d d i t i v e s no s u c h r i s k f a c t o r s a r e i n v o l v e d . The f a c t t h a t t h e l a c t i c a c i d o r g a n i s m s a r e t h e most i m p o r t a n t f o r good s i l a g e m a k i n g and t h a t t h e i r r a p i d d e v e l o p -ment i s e s s e n t i a l f o r s u c c e s s f u l e n s i l a g e h a s b e e n r e c o g n i z e d f o r some t i m e (Watson a nd N a s h , 1 9 6 0 ) . T h e r e i s no a d v a n t a g e i n e n s i l i n g y o u n g g r a s s o f h i g h d i g e s t i b i l i t y a n d h i g h p r o t e i n c o n t e n t i f t h e f e r m e n t a t i o n i s p o o r a nd t h e r e s u l t i s an u n -a c c e p t a b l e s i l a g e . The p u r p o s e o f t h e e x p e r i m e n t d e s c r i b e d h e r e i n was t o t e s t o n a f i e l d s c a l e t h e e f f e c t i v e n e s s o f a p o w d e r e d a d d i t i v e , - 2 -c o n t a i n i n g a d r y c u l t u r e o f l a c t o b a c i l l i , i n t h e p r e s e r v a t i o n o f f o r a g e n u t r i e n t s . O b j e c t i v e s : 1. To d e t e r m i n e t h e i n f l u e n c e o f t h e a d d i t i v e N u t r o L a c S i l a - A i d on t h e e f f l u e n t l o s s e s o f g r a s s s i l a g e . 2. To d e t e r m i n e by c h e m i c a l a n a l y s i s t h e e f f e c t o f N u t r o L a c S i l a - A i d on t h e f e r m e n t a t i o n o f g r a s s s i l a g e . 3. To a s s e s s t h e e f f e c t o f t h e a d d i t i v e o n t h e e f f i c i e n c y o f u t i l i z a t i o n o f g r a s s s i l a g e by l a c t a t i n g d a i r y cows. - 3 -2. LITERATURE SURVEY The e f f i c i e n t c o n s e r v a t i o n o f h e r b a g e i s e s s e n t i a l i f t h e f u l l p o t e n t i a l o f f o r a g e s a s f e e d i s t o be c o m p l e t e l y u t i l i z e d . E n s i l i n g i s t h e p r e s e r v a t i o n o f w e t c r o p s w i t h o r g a n i c a c i d s , p r i n c i p a l l y l a c t i c a c i d , p r o d u c e d by t h e f e r m e n t a t i o n o f a v a i l -a b l e c a r b o h y d r a t e s u n d e r a n a e r o b i c c o n d i t i o n s (Crawshaw, 1 9 7 7 ) . Zimmer (19 71) c o n c l u d e d t h a t p r e w i l t i n g , c h o p p i n g and e x c l u d i n g a i r a r e t h e m o s t i m p o r t a n t f a c t o r s a f f e c t i n g t h e f e r m e n t a t i o n , i n t h e s i l o . M c C u l l o u g h (1977) s u m m a r i z e d t h e m a i n f a c t o r s i n f l u e n c i n g f e r m e n t a t i o n a s : m o i s t u r e c o n t e n t o f t h e c r o p s ; b u f f e r i n g c a p a c i t y o f t h e c r o p ; a v a i l a b i l i t y o f w a t e r s o l u b l e c a r b o h y d r a t e s * , t y p e o f b a c t e r i a p r e s e n t and s p e e d o f f e r m e n t a t i o n . The c h a r a c t e r i s t i c s o f w e l l f e r m e n t e d s i l a g e s as l i s t e d b y L a n g s t o n e t a l . (1962) i n c l u d e d h i g h l e v e l s o f l a c t i c a c i d r e l a t i v e t o t h e l e v e l s o f a c e t i c and b u t y r i c a c i d s , l o w pH, l o w c o n t e n t o f ammonia and v o l a t i l e n i t r o g e n , and l o w numbers o f s p o r e f o r m i n g a n a e r o b e s . The s u c c e s s o f s i l a g e m a k i n g must be c o n s i d e r e d i n t e r m s o f a n i m a l p r o d u c t i o n . The q u a l i t y o f t h e consumed f e e d i s o f p r i m e i m p o r t a n c e when h i g h l e v e l s o f p r o d u c t i o n a r e a i m e d f o r w i t h o u t f e e d i n g s u p p l e m e n t s e x c e s s i v e l y . A h i g h l e v e l o f i n t a k e and d i g e s t i b i l i t y a r e n e c e s s a r y f o r h i g h a n i m a l p e r f o r m a n c e . B o t h t h e s e f a c t o r s a r e d e p e n d e n t on t h e q u a l i t y o f t h e c r o p a t t h e t i m e o f e n s i l i n g . A g ood q u a l i t y s i l a g e c a n n o t r e s u l t f r o m a p o o r q u a l i t y f o r a g e s i n c e t h e f e r m e n t a t i o n p r o c e s s i s b a s i c a l l y d e s t r u c t i v e . - 4 -F i v e advantages of h a r v e s t i n g and s t o r i n g crops as s i l a g e are g i v e n by McCullough (1978)!: 1. Improved cr o p p i n g p r a c t i c e s , 2. Reduced weather damage at h a r v e s t , 3. T o t a l mechanization, 4. H a r v e s t i n g maximum n u t r i e n t s per a c r e , 5. Improved f e e d i n g program. S i l a g e has a l s o shown t o have i t s disadvantages: 1. I t has a s h o r t storage l i f e a f t e r removing from the s i l o which r e q u i r e s d a i l y f e e d i n g f o r good u t i l i z a t i o n . 2. I t does not f i t i n t o market channels. 3. The high moisture content of s i l a g e n e c e s s i t a t e s the moving, s t o r i n g and h a n d l i n g of huge q u a n t i t i e s of weight d u r i n g s i l a g e h a r v e s t , storage and f e e d i n g . A major o b j e c t i v e i n the c o n s e r v a t i o n of a green crop as s i l a g e i s to preserve the m a t e r i a l w i t h a minimum l o s s of nu-t r i e n t s r e l a t i v e to the standing c r o p . The n u t r i e n t l o s s e s caused by waste can be c o n s i d e r a b l e (Gordon e t a l . , 1957). Un-der experimental c o n d i t i o n s the l o s s e s w i l l be i n the order of 15-20% o f the dry matter, 20-25% of the d i g e s t i b l e crude p r o t e i n and 25-30% of the s t a r c h e q u i v a l e n t (Murdoch, 1961). Dry matter and n u t r i e n t l o s s e s over 5 0% have been r e p o r t e d . In f a c t , the s i l a g e can be i n e d i b l e when improper s i l a g e making techniques are used. In r e c e n t years much r e s e a r c h has been devoted to the c o n t r o l of fermentation by the a p p l i c a t i o n of a d d i t i v e s to the e n s i l e d herbage. S e v e r a l s t u d i e s have been conducted u s i n g laboratory-made s i l a g e s or samples from s i l a g e s of a commercial s c a l e , which i n d i c a t e d the i n f l u e n c e of a d d i t i v e s on s i l a g e m i c r o f l o r a and o r g a n i c a c i d content. - 5 -D i f f e r e n t c a t e g o r i e s a r e u s e d by r e s e a r c h e r s t o c l a s s i f y a d d i t i v e s (Watson a n d N a s h , I960; Thomas, 1978). A d d i t i v e s f i t b r o a d l y i n t o t h r e e m a i n c a t e g o r i e s a c c o r d i n g t o mode o f a c t i o n : 1. S t i m u l a n t s , . 2. A c i d i f i e r s , 3. S t e r i l a n t s . A c c o r d i n g t o t h e c h a r a c t e r i s t i c s o f t h e m a j o r i n g r e d i e n t s t h e y may be d i v i d e d i n t o f o u r d i f f e r e n t g r o u p s : 1. I n o r g a n i c c h e m i c a l s , 2. O r g a n i c c h e m i c a l s , 3. C e r e a l b y - p r o d u c t s , 4. F e r m e n t a t i o n p r o d u c t s . The t e r m " s i l a g e q u a l i t y " i s g e n e r a l l y u s e d t o i n d i c a t e t h e s u c c e s s o f t h e f e r m e n t a t i o n p r o c e s s . ' The f e e d i n g v a l u e i s u s u a l l y h i g h l y c o r r e l a t e d w i t h t h e s i l a g e q u a l i t y b u t c a n o n l y be d e t e r m i n e d b y i n t a k e and d i g e s t i b i l i t y s t u d i e s . Of t h e d i f f e r e n t m ethods w h i c h h a v e b e e n p r o p o s e d t o ^ . c l a s -s i f y s i l a g e f e r m e n t a t i o n , t h e k e y d e v e l o p e d by F l i e g (19 38) was m o s t w i d e l y u s e d a n d r e c o g n i z e d . Zimmer (1966) made a r e - e v a l u a t i o n o f t h a t k e y by t a k i n g t h e v a l u e s o f t h e a c i d s as t h e i r p e r c e n t a g e o f t h e t o t a l a c i d and by b a s i n g a s y s t e m o f p o i n t s o n t h e s e p e r c e n t a g e s . F o r t h e c a l c u l a t i o n o f t h e F l i e g i n d e x , t h e p e r c e n t a g e o f l a c t i c , a c e t i c and b u t y r i c a c i d i n t h e s i l a g e h a v e t o be d e t e r m i n e d . The h i g h e s t s c o r e o f 100 p o i n t s c a n o n l y be o b t a i n e d i f a c e t i c a c i d a c c o u n t s f o r n o t more t h a n 15%, b u t y r i c n o t more t h a n 1.5% and l a c t i c o v e r 75% o f t h e s e t h r e e a c i d s . Many r e s e a r c h e r s p r e s e n t e d d a t a i n d i c a t i n g a s i g n i f i c a n t c o r r e l a t i o n b e t w e e n t h e F l i e g i n d e x and t h e i n t a k e and d i g e s t -i b i l i t y o f s i l a g e s . U c h i d a and S u t o h (1973) e n s i l e d I t a l i a n - 6 -r y e g r a s s u s i n g v a r i o u s c h o p p i n g and w i l t i n g t e c h n i q u e s . The F l i e g s c o r e s o b t a i n e d v a r i e d f r o m 18 t o 100. The TDN v a l u e s w e r e f o u n d t o be d i r e c t l y r e l a t e d t o t h e F l i e g i n d e x , t h e c o r r e l a t i o n b e i n g .992. The f u n d a m e n t a l r o l e o f l a c t i c a c i d b a c t e r i a i n s i l a g e m a k i n g h a s b e e n r e c o g n i z e d f o r a l o n g t i m e and i n o c u l a t i o n o f h e r b a g e w i t h t h e s e m i c r o - o r g a n i s m s h a s b e e n t r i e d by a number o f r e s e a r c h e r s . W h i t t e n b u r y (1961) and W i e r i n g a and B e c k (1964) s t r e s s e d some c r i t e r i a w h i c h a p o t e n t i a l l a c t i c a c i d p r o d u c i n g o r g a n i s m s h o u l d meet. They p o s t u l a t e d t h a t a s u i t a b l e o r g a n i s m : 1. m u s t h a v e a h i g h g r o w t h r a t e a n d be a b l e t o c o m p e t e w i t h and d o m i n a t e o t h e r o r g a n i s m s o c c u r i n g i n t h e s i l a g e , 2. m u s t be h o m o f e r m e n t a t i v e ( p u r i t y o f l a c t i c a c i d f e r m e n t a t i o n ) , 3. must be a c i d - t o l e r a n t and p r o d u c e a l o w pH q u i c k l y , 4. m u s t be a b l e t o f e r m e n t d i f f e r e n t c a r b o h y d r a t e s . The i n o c u l a u s e d i n most s t u d i e s c o n s i s t o f a m i x t u r e o f d i f f e r e n t s t r a i n s o f h o m o f e r m e n t a t i v e l a c t o b a c i l l i ( m a i n l y . L a c t o b a c i l l u s p l a n t a r u m ) s e l e c t e d f o r t h e i r a b i l i t y t o f e r m e n t t h e s o l u b l e c a r b o h y d r a t e s o f g r a s s and f o r t h e i r a b i l i t y t o g r o w . o v e r a r a n g e o f t e m p e r a t u r e . I n t h e e a r l y 1900's F r e n c h w o r k e r s a d d e d s u c c e s s f u l l y c u l t u r e s o f l a c t o b a c i l l i t o b e e t p u l p s i l a g e , l o w e r i n g i t s b u t y r i c a c i d c o n t e n t a n d p r o d u c i n g a more p l e a s a n t s m e l l ( C r o l b o i s , 1909). W a t s o n (1939) and Watson and N a s h (1960) s u m m a r i z e d t h e e a r l y w o r k u s i n g m i c r o b i a l c u l t u r e s , 'They f o u n d - 7 -t h a t i n o c u l a t i o n with a l a c t i c c u l t u r e d i d not show an advantage, but they suggested t h a t i t should be added with molasses or whey to p r o t e i n r i c h c r o p s , which are d e f i c i e n t i n water s o l u b l e carbohydrate (WSC) , to make the:?fermentation process even more c e r t a i n . Of the v a r i e t y of f a c t o r s i n f l u e n c i n g the success of an i n o c u l a t i o n the c h o i c e of the used herbage s p e c i e s seemed to be most important. Normally the crop had an e x t e n s i v e • m i c r o f l o r a which was capable of l a c t i c a c i d f e r m e n t a t i o n which, i n t u r n , d i d not g i v e improved r e s u l t s a f t e r i n o c u l a t i o n . The e f f e c t of i n o c u l a t i o n i n r e s p e c t t o the content of water s o l u b l e carbohydrates i n forage has been s t u d i e d by many workers. Beck (1978) r e p o r t e d t h a t the s t u d i e s by Beck (1965), Gross (1969) and Gross and Riebe (1974) i n d i c a t e d t h a t the success of an i n o c u l a t i o n of f r e s h grass with s e l e c t e d s t r a i n s of L. plantarum was dependent on the number of c e l l s a p p l i e d to the p l a n t m a t e r i a l . McDonald e t a l . (1964) showed t h a t a good q u a l i t y s i l a g e was obtained i r r e s p e c t i v e of the i n o c u -l a t i o n with Lolium m u l t i f l o r u m ( I t a l i a n r y e grass) of 16.2% WSC. There was 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 between i n o c u l a t e d and c o n t r o l s i l a g e . However, the s i l a g e c o n t a i n i n g the a d d i t i v e l o s t more e f f l u e n t . The b a c t e r i a count showed t h a t by the t h i r d day the Gram-negative b a c t e r i a had i n c r e a s e d i n the un-t r e a t e d laboratory-made s i l a g e but had decreased to a n e g l i g i b l e amount i n the i n o c u l a t e d s i l a g e . When D a c t y l i s glomerata (cocksfoot) c o n t a i n i n g 4.3% WSC was e n s i l e d the i n o c u l a t i o n showed some success, r e f l e c t e d i n a reduced pH value and a - 8 -markedly i n c r e a s e d i n t a k e w i t h sheep. The e n s i l a g e of a crop of T r i f o l i u m pratense (red c l o v e r ) c o n t a i n i n g 9.7% WSC d i d not show an e f f e c t o f i n o c u l a t i o n on s i l a g e i n t a k e and d i g e s t -i b i l i t y (McDonald e t a l . , 1965). The b a c t e r i o l o g i c a l s t u d i e s i n d i c a t e d t h a t i n small laboratory-made batches, examined 4 days a f t e r e n s i l i n g , the count of l a c t i c a c i d b a c t e r i a was h i g h e r i n the i n o c u l a t e d s i l a g e r e l a t i v e to the c o n t r o l . The e f f e c t of an i n o c u l a t i o n t ogether w i t h an a d d i t i o n of sugar was s t u d i e d by Wieringa (1960,1961), McDonald e t a l . , (1965) Svensson and T v e i t (1964) and L e s i n s and Schulz (1968). In most cases the combination of i n o c u l a t i o n and added sugar produced p o s i t i v e r e s u l t s . However, the a d d i t i o n of an i n o c -ulum d i d not improve the p r e s e r v i n g e f f e c t compared t o an a d d i t i o n of sugar alone. These f i n d i n g s are i n agreement with the more r e c e n t r e s u l t s (Gross, 19 69> Papendick and Bruhn, 1970) . A main f a c t o r c a u s i n g u n d e s i r a b l e f e r m e n t a t i o n has been rep o r t e d to be the i n v a s i o n of a i r d u r i n g the e a r l y stage a f t e r e n s i l i n g (Zimmer, 1971; Ruxton and McDonald, 1974; Ohyama et a l . , 1975). In the s t u d i e s by Ohyama et al.(1975) c o n t r o l s i l a g e s to which a i r was i n t r o d u c e d a t an e a r l y stage of e n s i l i n g always showed poor q u a l i t y . The i n t r o d u c e d a i r caused an a e r o b i c c o n d i t i o n which enhanced the m u l t i p l i c a t i o n of Gram-negative b a c t e r i a . As a r e s u l t the growth of l a c t o b a c i l l i was suppressed and the pH d i d not f a l l s u f f i c i e n t l y . A f t e r the d e p l e t i o n o f oxygen the growth of C l o s t r i d i a was promoted which r e s u l t e d - 9 -i n a p o o r q u a l i t y s i l a g e . The a d d i t i o n o f g l u c o s e a t a r a t e o f 1 and 2% o f t h e f r e s h m a t e r i a l t o a e r a t e d s i l a g e s d i d n o t i m p r o v e t h e q u a l i t y o f c o c k s f o o t s i l a g e s b u t s i l a g e made o f ' ; I t a l i a n r y e g r a s s showed t o be o f b e t t e r q u a l i t y (Ohyama e t a l . , 1 9 7 5 ) . The e f f e c t o f a p p l i c a t i o n o f a c u l t u r e o f L. p l a n t a r u m i n a d d i t i o n t o g l u c o s e was i n v e s t i g a t e d i n t h e same s t u d y . The a d d i t i o n o f b o t h g l u c o s e and l a c t o b a c i l l i r e s u l t e d i n s i l a g e o f e x c e l l e n t o r s a t i s f a c t o r y q u a l i t y . A r a p i d i n c r e a s e o f l a c t o b a c i l l i o c c u r r e d a n d t h e number o f G r a m - n e g a t i v e b a c t e r i a d e c r e a s e d e v e n t h o u g h t h e r e was an i n v a s i o n o f a i r a t t h e e a r l y s t a g e o f f e r m e n t a t i o n . The e f f e c t o f n i t r o g e n f e r t i l i z e r s on t h e e n s i l i n g c h a r a c t e r i s t i c s o f d i f f e r e n t h e r b a g e s p e c i e s was s t u d i e d by J o n e s e t a l . (1961) and J o n e s ( 1 9 7 0 a , 1 9 7 0 b ) . T h e y f o u n d t h a t DM and WSC c o n t e n t d e c r e a s e d as t h e l e v e l o f n i t r o g e n f e r t i -l i z e r i n c r e a s e d , p e r e n n i a l r y e g r a s s b e i n g h i g h e r i n WSC b u t l o w e r i n CP c o n t e n t "than c o c k s f o o t a t e a c h n i t r o g e n l e v e l . C o c k s f o o t was f o u n d t o h a v e a h i g h e r b u f f e r i n g c a p a c i t y re5-l a t i v e t o r y e g r a s s . C o c k s f o o t s i l a g e s w e r e w e l l p r e s e r v e d o n l y when t h e l o w e s t f e r t i l i z e r l e v e l (50 k g N/ha) was a p p l i e d , w h e r e a s t h e r y e g r a s s s i l a g e s w e r e w e l l p r e s e r v e d e v e n a t a N l e v e l o f 200 k g / h a . The a p p l i c a t i o n o f an i n o c u l u m d i d n o t i m p r o v e t h e q u a l i t y o f t h e c o c k s f o o t s i l a g e s . They w e r e v e r y l o w i n l a c t i c a c i d c o n t e n t and h i g h i n pH and b u t y r i c a c i d c o n t e n t . However, t h e a d d i t i o n o f s u c r o s e (5 g/100 g f r e s h - 10 -g r a s s ) t o c o c k s f o o t s i g n i f i c a n t l y i m p r o v e d t h e s i l a g e q u a l i t y as shown b y a r e d u c e d pH, ammonia a nd b u t y r i c a c i d c o n t e n t and i n c r e a s e d c o n t e n t o f l a c t i c a c i d . The a d d i t i o n o f s u c r o s e h a d no s i g n i f i c a n t e f f e c t on t h e c o m p o s i t i o n o f r y e g r a s s s i l a g e . S i l a g e i n t a k e h a s b e e n s t u d i e d i n t e n s i v e l y by r e s e a r c h e r s . A l o w i n t a k e has o f t e n b een a s s o c i a t e d w i t h a l o w DM c o n t e n t o f t h e s i l a g e s . W i l k i n s e t a l . (1971) showed t h a t d r y m a t t e r i n t a k e was p o s i t i v e l y r e l a t e d t o DM c o n t e n t o f t h e s i l a g e . The d e p r e s s i o n i n i n t a k e d o e s n o t a p p e a r t o r e l a t e t o t h e m o i s t u r e l e v e l p e r s e b a s e d on t h e f a c t t h a t DM i n t a k e i s n o t r e d u c e d when t h e m o i s t u r e c o n t e n t o f a w i l t e d s i l a g e i s i n e c r e a s e d p r i o r t o f e e d i n g b y w e t t i n g (Thomas e t a l . , 1961). The l o w i n t a k e f o r l o w DM s i l a g e s a p p e a r s t o be r e l a t e d t o t h e e x t e n t o f f e r m e n t a t i o n d u r i n g e n s i l i n g ( L a n c a s t e r e t a l . , 1974• D o n a l d s o n a n d E d w a r d s , 1976). McLeod a n d W i l k i n s (1970) f o u n d t h a t t h e v o l u n t a r y i n t a k e o f s i l a g e by r u m i n a n t s c a n be l i m i t e d b y i t s c o n t e n t o f o r g a n i c a c i d s . M c L eod e t a l . ."(1970) d e m o n s t r a t e d t h e r e l a t i o n s h i p b e t w e e n s i l a g e pH and i n t a k e by a d d i n g l a c t i c a c i d t o g r a s s s i l a g e o f h i g h pH. The d r y m a t t e r i n t a k e d r o p p e d by 22% when t h e pH was r e d u c e d f r o m 5.4 t o 3.8, w h i l e t h e l a c t i c a c i d c o n t e n t i n c r e a s e d f r o m 5.4 t o 11.3% o f t h e s i l a g e d r y m a t t e r . I n c o n t r a s t , p a r t i a l n e u t r a l i z a t i o n o f s i l a g e h a s 'been-.shown t o i n c r e a s e i n t a k e (McLeod e t a l . , 1970). The a d d i t i o n o f s o d i u m b i c a r b o n a t e t o s i l a g e t o i n c r e a s e t h e pH f r o m 4.0 t o - 11 -about 5.4 resulted i n s i g n i f i c a n t i n c r e a s e s i n DM intake w h i c h r a n g e d f r o m 9.7 t o 20.7%. S i m i l a r i n c r e a s e s i n Intake were r e p o r t e d by K i n g (1943) and Thomas and W i l k i n s o n (1975) u s i n g s o d i u m b i c a r b o n a t e as a b u f f e r . The p a r t i a l n e u t r a l i z a t i o n d i d n o t e f f e c t t h e d i g e s t i b i l i t y o f d r y m a t t e r , o r g a n i c m a t t e r , g r o s s e n e r g y o r c e l l u l o s e and d i d n o t e f f e c t t h e n i t r o g e n r e t e n t i o n (McLeod a n d W i l k i n s , 1970; M c L e o d e t a l . , 1970; Thomas a n d W i l k i n s o n , 1975). W i l k i n s e t a l . (1971) f o u n d t h a t v o l u n t a r y i n t a k e was p o s i t i v e l y c o r r e l a t e d (P<;.001) w i t h t h e c o n t e n t s o f DM, CP and l a c t i c a c i d as a p e r c e n t a g e o f t o t a l a c i d s a n d t h e F l i e g i n d e x a n d n e g a t i v e l y w i t h t h e p e r c e n t a g e o f t o t a l N p r e s e n t as ammonia. The c o n t e n t o f l a c t i c a c i d h a d a s l i g h t l y p o s i t i v e c o r r e l a t i o n w i t h DM i n t a k e , w h e r e a s a c e t i c a c i d c o n t e n t h a d a s i g n i f i c a n t n e g a t i v e c o r r e l a t i o n w i t h DM i n t a k e f o r g r a s s e s . A high;- q u a l i t y o f f e r m e n t a t i o n seems d e s i r a b l e a c c o r d i n g t o t h e r e s u l t s o f W i l k i n s e t a l . (1971) b e c a u s e i t i s r e l a t e d b o t h w i t h r e l a t i v e l y h i g h s i l a g e i n t a k e and w i t h l o w l o s s e s d u r i n g t h e e n s i l i n g p r o c e s s . The r e l a t i o n s h i p s t a t e d a b o v e i s i n c o n t r a r y t o t h e f i n d i n g s o f McLeod e t a l . (19 70) t h a t t h e a d d i t i o n o f l a c t i c a c i d t o s i l a g e l o w e r s i n t a k e . W i l k i n s e t a l . (1971) a l s o f o u n d t h a t i n t a k e i n c r e a s e d w i t h i n c r e a s i n g pH?and c o n c l u d e d t h a t l o w i n t a k e o f s i l a g e i s a s s o c i a t e d b o t h w i t h e x t e n s i v e d e g r a d a t i o n i n s i l a g e s o f l o w f e r m e n t a t i o n q u a l i t y a n d w i t h e x t e n s i v e f e r m e n t a t i o n i n s i l a g e s o f l o w pH. H u t c h i n s o n a n d W i l k i n s (1971) s t u d i e d t h e e f f e c t o f - 12 -a c e t a t e on s i l a g e i n t a k e . A h i g h a c e t i c a c i d l e v e l i s i n d i c -a t i v e o f a p a r t i c u l a r t y p e o f f e r m e n t a t i o n . A c e t i c a c i d i s f o r m e d b y h e t e r o l a c t i c f e r m e n t a t i o n o f s u g a r s a n d o r g a n i c a c i d s and by t h e b r e a k d o w n o f amino a c i d s d u r i n g s e c o n d a r y f e r m e n -t a t i o n . T h r e e p e r e n n i a l r y e g r a s s s i l a g e s w i t h a r a n g e o f a c e t i c a c i d c o n t e n t s (2.0-8.V8%) w e r e f e d t o s h e e p . The pH and DM c o n t e n t was k e p t a t t h e same l e v e l f o r a l l s i l a g e s (4.1 and 25.3%). The pH v a l u e was c o n t r o l l e d by a d d i n g p o t a s -s i u m h y d r o x i d e . When t h e d i f f e r e n t d i e t s w e r e f e d t o s h e e p no s i g n i f i c a n t d i f f e r e n c e i n i n t a k e , d i g e s t i b i l i t y a n d n i t r o g e n r e t e n t i o n c o u l d be d e t e c t e d . I t was c o n s i d e r e d u n l i k e l y t h a t a h i g h a c e t a t e l e v e l p e r s e w i l l r e s u l t i n a l o w i n t a k e o f s i l a g e . Montgomery e t a l . (1963) and McLeod e t a l . (1970) f o u n d d i f f e r e n t e f f e c t s on i n t a k e f r o m t h e f e e d i n g o f an a c i d c o m p a r e d t o t h e s a l t o f t h a t a c i d . T h e s e a u t h o r s s u g g e s t e d t h e e f f e c t o f an a c i d b a s e i m b a l a n c e . G o r d o n e t a l . (1964) u s e d e i g h t l o t s o f o r c h a r d g r a s s w h i c h r e p r e s e n t e d a w i d e r a n g e i n c o m p o s i t i o n , t o s t u d y t h e c h e m i c a l c o n s t i t u e n t s i n f l u e n c i n g d r y m a t t e r i n t a k e w i t h l a c t a t i n g d a i r y c o ws. He f o u n d t h a t t h e d r y m a t t e r c o n s u m p t i o n was p o s i t i v e l y c o r r e l a t e d (P-<c .01) w i t h DM a n d l a c t i c a c i d c o n t e n t and n e g a -t i v e l y w i t h pH a n d a c e t i c a c i d c o n t e n t . B u t y r i c a n d p r o p i o n i c a c i d c o n t e n t was n e g a t i v e l y c o r r e l a t e d w i t h i n t a k e a t P-c.05. S i m i l a r r e s u l t s w e r e o b t a i n e d by Brown a nd R a d c l i f f e (1972) b a s e d on 15 g r a s s s i l a g e s a n d M c C u l l o u g h (1961) b a s e d on 17 s i l a g e s r e p r e s e n t i n g s e v e r a l c r o p s . - 13 -I n c o n c l u s i o n t h e p r e s e n t i n f o r m a t i o n s u g g e s t s t h a t t h e a p p l i c a t i o n o f an i n o c u l u m may r e s u l t i n a b e n e f i c i a l e f f e c t on t h e s i l a g e q u a l i t y , p r o v i d e d t h a t WSC a r e a d e q u a t e ( 6 - 8 % ) . An i m p r o v e m e n t o f t h e s i l a g e f e r m e n t a t i o n c a n be a c h i e v e d when a p r o l i f e r a t i o n o f u n d e s i r a b l e m i c r o - o r g a n i s m s i s l i k e l y t o o c c u r r ( i e . i m p e r f e c t s e a l i n g o f t h e s i l o o r c o n t a m i n a t i o n o f t h e h e r b a g e w i t h e a r t h ) . The i n o c u l a t i o n o f a s u g a r - r i c h c r o p d i d n o t i m p r o v e s i l a g e q u a l i t y . C r o p s l o w i n s o l u b l e c a r b o -h y d r a t e s d i d n o t i m p r o v e i n q u a l i t y by i n o c u l a t i o n e i t h e r . L i b e r a l N f e r t i l i z a t i o n i m p a i r e d s i l a g e q u a l i t y e v e n more. The o b s e r v a t i o n s b y McLeod e t a l . (1970) i n d i c a t e d t h a t a r e d u c t i o n i n s i l a g e c o n s u m p t i o n h a s t o be e x p e c t e d when an e x t e n s i v e l a c t a t e f e r m e n t a t i o n h a s o c c u r r e d . R e s u l t s o f o t h e r r e s e a r c h e r s showed t h a t t h e l a c t i c a c i d c o n t e n t was e i t h e r p o s i t i v e l y o r n e g a t i v e l y c o r r e l a t e d w i t h DM i n t a k e . The l e v e l o f l a c t i c a n d t o t a l a c i d s a l s o p l a y e d a r o l e . The c o n t e n t o f l a c t i c a c i d a s a p e r c e n t a g e o f t o t a l a c i d s a p p e a r e d t o be more r e l a t e d t o i n t a k e t h a n t h e l a c t i c a c i d c o n t e n t i t s e l f . O t h e r f a c t o r s s u c h as r u m i n a l o s m o l a l i t y , c o n t e n t o f a m i n e s , w a t e r s o l u b l e n i t r o g e n a n d w a t e r s o l u b l e c a r b o h y d r a t e s h a v e b e e n i n v e s t i g a t e d . Many f a c t o r s h a v e b e e n i m p l i c a t e d as i n h i b i t o r s o f s i l a g e i n t a k e . I t i s p r o b a b l e t h a t a c o m b i n a t i o n o r i n t e r a c t i o n o f s e v e r a l f a c t o r s i s r e s p o n s i b l e f o r a r e d u c e d i n t a k e o f f e r m e n t e d f e e d s . - 14 -3. MATERIALS AND METHODS 3.1. F i e l d s The f o l l o w i n g e x p e r i m e n t was c a r r i e d o u t on t h e R e s e a r c h S t a t i o n A g a s s i z , B.C. The o r c h a r d g r a s s w h i t e - c l o v e r m i x t u r e was c u t and h a r v e s t e d b e t w e e n t h e d a t e s o f May 17 and May 1 9 , 1978. F i e l d 1, w h i c h was m a t u r e , was mown on t h e f i r s t d a y a f t e r a r a i n y week. The g r a s s was l e f t on t h e f i e l d t o w i l t f o r a s h o r t t i m e . I t was c h o p p e d and e n s i l e d i n t h e a f t e r n o o n o f d a y 1 and m o r n i n g and a f t e r n o o n o f d a y 2. A d d i t i o n a l g r a s s h a d t o be c u t t o f i l l t h e s i l o s . So f i e l d 9, w h i c h h a d b e e n p a s t u r e d i n s p r i n g , was mown on May 18 and 19, w i l t e d f o r a few h o u r s and t h e n h a r v e s t e d . B o t h f i e l d s h a d be e n f e r t i l i z e d w i t h 76 k g n i t r o g e n p e r h e c t a r e i n s p r i n g . T o t a l h a r v e s t t o o k p l a c e w i t h i n 48 h o u r s . 3.2. F o r a g e The f o r a g e was w e i g h e d a s i t came f r o m t h e f i e l d . Two s i l o s w e r e f i l l e d w i t h a l t e r n a t e l o a d s o f a p p r o x i m a t e l y 2 t o n n e s t o e n s u r e a u n i f o r m , e n s i l a g e i n b o t h s i l o s . The a d d i t i v e , N u t r o L a c S i l a - A i d , c o n t a i n i n g a d r i e d c u l t u r e o f l a c t i c a c i d b a c i l l i was a d d e d t o t h e f o r a g e g o i n g i n t o one s i l o a t a r a t e o f 1/2 k g p e r t o n n e o f wet m a t e r i a l . The a d d i t i v e N u t r o L a c S i l a - A i d was p r o v i d e d c o u r t e s y o f S t a r - L a b s I n c . , M i s s o u r i . The a d d i t i v e was s p r e a d u n i f o r m l y on t o p o f e a c h l o a d and was m i x e d w i t h t h e f o r a g e w h i l e b e i n g b l o w n i n t h e s i l o . The s e -c o n d s i l o was u s e d as a c o n t r o l and d i d n o t c o n t a i n an a d d i t i v e . - 15 -A sample of approximately 5 kg was c o l l e c t e d from each lo a d as i t passed along the conveyor p r i o r to e n t e r i n g the blower. The samples were then put i n the f r e e z e r . On the l a s t day of e n s i l i n g each of the 5 kg samples c o l l e c t e d was w e l l mixed and two sub-samples of one k i l o g r a m were taken and oven d r i e d a t 60°C f o r 72 hours. The d r i e d samples were ground and composited to f i v e f i n a l samples, each r e p r e s e n t i n g 3-4 l o a d s , and analysed i n d u p l i c a t e f o r t o t a l n i t r o g e n (N) by block d i g e s t i o n and the Technicon a u t o - a n a l y z e r procedures and f o r a c i d d e t e r g e n t f i b e r (ADF) and l i g n i n (ADL) by the m i c r o - d i g e s t i o n technique of Waldern (1971) and f o r ash by ashing a 2 g sample at 600°C f o r 2 hours i n the mu f f l e furnace. 3.3. S i l o s Both wooden stave s i l o s used i n t h i s experiment measured 3.3 m i n diameter, 10.7 m i n he i g h t and had a c a p a c i t y of 40 tonnes. They were hosed down s e v e r a l times i n the week preceding the e n s i l i n g to prevent a i r l e a k s . Each s i l o was equipped with a trough around the base to c o l l e c t seepage l e a k i n g out of the w a l l s and a t i l e drainage system i n the f l o o r which conducted the r u n - o f f to a sump. The e n s i l a g e was packed d u r i n g f i l l i n g , the top se a l e d with p l a s t i c and weighted w i t h t i r e s . Thermocouples were i n s e r t e d at the one t h i r d and two t h i r d l e v e l s o f both s i l o s i n order to get i n f o r m a t i o n on the q u a l i t y of fer m e n t a t i o n . -16 -3.4. E f f l u e n t and S i l a g e T e m p e r a t u r e D a i l y v o l u m e o f e f f l u e n t f r o m e a c h s i l o was e s t i m a t e d by m e a s u r i n g r a t e o f f l o w f o r a c e r t a i n t i m e i n t e r v a l a t 8.00 and 16.0 0 h o u r s f o r 30 d a y s . The s a m p l i n g t i m e r a n g e d f r o m 15 m i n u t e s d u r i n g t h e f i r s t f e w d a y s a f t e r e n s i l i n g t o 1 h o u r a t t h e end o f t h e e f f l u e n t c o l l e c t i o n p e r i o d . S a m p l e s o f e f f l u e n t were t a k e n t w i c e d a i l y and a n a l y z e d f o r d r y m a t t e r (DM) by o v e n d r y i n g a t 70°C f o r 72 h o u r s , f o r pH, t o t a l n i t r o g e n a n d a s h . DM, pH and a s h were d e t e r m i n e d on a p o o l e d d a i l y s a m p l e . The n i t r o g e n a n a l y s i s was c a r r i e d o u t on a o n e - d a y -s a m p l e f o r t h e f i r s t f e w d a y s and on a t w o - d a y - p o o l e d - s a m p l e f o r t h e r e m a i n d e r o f t h e c o l l e c t i o n p e r i o d . A l l d e t e r m i n a t i o n s e x c e p t pH w e r e d e t e r m i n e d i n d u p l i c a t e . D a i l y l o s s o f e f f l u e n t DM, p r o t e i n and a s h were c a l c u l a t e d . The t e m p e r a t u r e s w e r e r e a d a t t h e same t i m e a s t h e e f f l u e n t was m e a s u r e d . The t e m p e r a t u r e r e a d i n g s were c o n t i n u e d t w i c e d a i l y u n t i l t h e end o f J u l y . An a v e r a g e d a i l y t e m p e r a t u r e was c a l c u l a t e d . 3.5. S i l a g e B o t h s i l o s w e r e o p e n e d i n e a r l y J u l y , 46 d a y s a f t e r t h e l a s t d a t e o f e n s i l i n g and t h e s i l a g e s w e r e f e d f o r 15 c o n -s e c u t i v e w e e k s . The s t o r a g e p e r i o d f o r t h e b o t t o m l a y e r s i n t h e s i l o s was 154 d a y s , c a l c u l a t e d as t h e t i m e f r o m t h e f i r s t d a y o f e n s i l i n g t o t h e l a s t d a y o f f e e d i n g . The s i l a g e was r e m o v e d f r o m t h e s i l o on a d a i l y b a s i s . C a r e was t a k e n t o remove o n l y a s much s i l a g e a s w o u l d be r e q u i r e d f o r a g i v e n d a y . I f t h e amount was o v e r e s t i m a t e d t h e r e m a i n i n g s i l a g e - 17 -was i n c l u d e d f o r t h e n e x t d a y ' s f e e d i n g . S i l a g e t h a t warmed up t o o much was n o t f e d . The s i l a g e s w e r e s a m p l e d e v e r y week by t a k i n g a r e p r e s e n t a t i v e 500 g s a m p l e f r o m t h e p i l e o f s i l a g e t h a t h a d b e e n removed f r o m t h e s i l o f o r t h a t p a r t i c u l a r d a y . The s i l a g e s a m p l e s w ere f r o z e n i m m e d i a t e l y . A t t h e same t i m e a s m a l l s a m p l e was t a k e n f r o m e a c h p i l e t o d e t e r m i n e t h e pH o f t h e f r e s h s i l a g e as i t was removed f r o m t h e t o w e r s i l o s . The pH was d e t e r m i n e d by m a c e r a t i n g 25 g o f s i l a g e t o g e t h e r w i t h 225 ml o f d i s t i l l e d w a t e r i n a k i t c h e n b l e n d e r . B e f o r e c a r r y i n g o u t t h e DM d e t e r m i n a t i o n t h e s a m p l e s w e r e m i x e d w i t h c h o p p e d d r y i c e , l e f t t o s t a n d f o r 1/2 h o u r t o c o o l e v e n more, t h e n f i n e l y g r o u n d w i t h a h i g h s p e e d b l e n d e r . A t l e a s t 2 4 h o u r s w ere a l l o w e d f o r t h e d r y i c e t o d i s s i p a t e b e f o r e u s i n g t h e s a m p l e s f o r f u r t h e r a n a l y s i s . DM was o b t a i n e d by t o l u e n e d i s t i l l a t i o n , w h i c h p r o v i d e s a more c o r r e c t e s t i m a t e o f t h e t r u e DM c o n t e n t o f s i l a g e s . The d i s t i l l a t i o n p r o c e d u r e as d e s c r i b e d by Dewar and M c D o n a l d (1961) was s l i g h t l y m o d i f i e d . S a m p l e s • o f 50 g w e r e u s e d f o r t h e d i s t i l l a t i o n . A l l d e t e r m i n a - • • t i o n s w e r e c a r r i e d o u t i n d u p l i c a t e . ' The DM was a l s o d e t e r m i n e d by o v e n d r y i n g a t 6 0°C f o r 7 2 h o u r s f o r t h e s a m p l e s f r o m t h e l a s t n i n e weeks o f t h e e x p e r i m e n t . T o t a l N, a s h , ADF, l i g n i n and n e u t r a l d e t e r g e n t f i b e r (NDF) w e r e d e t e r m i n e d on an o v e n d r i e d s a m p l e . NDF was a n a l y s e d o n l y on t h e s a m p l e s f r o m t h e l a s t n i n e w e e k s . T o t a l N, ADF, l i g n i n and NDF d e t e r m i n a t i o n s w e r e c a r r i e d o u t i n d u p l i c a t e . The s o l u b l e n i t r o g e n f r a c t i o n was d e t e r m i n e d on a weak a c i d e x t r a c t (.1 N HC1) o f t h e f r o z e n - 18 -sampler-;by the Kjeldahl method. The d i g e s t i b l e energy (DE) content of the silages was calculated by the following formula: DE(Mcal/kg) - 5.4-0.057*(%ADF).1 A l l silage removed from the s i l o was weighed to determine losses due to e n s i l i n g and fermentation. 3.6. An ima1s Twelve Holstein cows i n early to mid l a c t a t i o n were subdivided into two groups of similar age, body weight, stage of l a c t a t i o n and potential milk y i e l d . The cows i n group I were 3.7 months older and 10 kg l i g h t e r (Table 1), the average age and weight of a l l cows being 4 6.5 months and 57 7 kg. The group I animals were ahead i n number of lactations but s l i g h t l y behind in stage of current l a c t a t i o n . One animal had to be replaced during the adjustment period preceding the experiment due to digestive disturbances. The rapid change from pasture to silage as the only forage most probably caused t h i s high producing cow to get sick and a l l the cows were suffering from scours for the f i r s t few weeks. No animals were l o s t during the course of the experiment. One animal, however, was sick during the f i r s t d i g e s t i b i l i t y t r i a l . Group I was fed control silage while group II was fed NutroLac silage during the eight-day adjustment period and 1 . Waldern, D.E. Equation developed for B r i t i s h Columbia Ministry of Agriculture, BCMA. Table 1: Age, weight and l a c t a t i o n of the animals on experiment. Age (mos) Weight (kg) L a c t . (no. ) wks of present l a c t . Group I 48.3 (15.7) 572 (50.7) 2 .50 (1.3) 8.2 (3.9) Group II 44". .7 (14.3) 582 (32.9) 2.16 (1.1) 10.2 (3.5) Standard d e v i a t i o n i n brack e t s the f i r s t seven week experimental p e r i o d . The cows were allowed one week change-over';. betweehv-the:'two:. treatment ^ periods t o prevent a c a r r y - o v e r e f f e c t , and the a l t e r n a t e forage was fed f o r s i x weeks. Due to a shortage of s i l a g e the second p e r i o d had to be reduced to s i x weeks from the i n t i t i a l seven. The f i r s t e xperimental p e r i o d began on J u l y 12 and the second p e r i o d on September 6. The t r i a l was completed on October 18, 1978. Cows were housed i n a f r e e s t a l l barn and fed i n d i v i d u a l l y . The barn was equipped with e l e c t r o n i c gates to ensure t h a t each cow had access o n l y t o her own feed. The cows c o u l d eat a t anytime d u r i n g the day. They were provided with feed t h r e e times a day; at 5.00 h, 10.00 h and 14.30 h. Cows had access to c o b a l t i o d i z e d s a l t at a l l times. They were milked i n the p a r l o r l i k e the main herd. A g r a i n mixture c o n s i s t i n g o f 22% crude p r o t e i n (CP) was fed at a r a t e of 1 kg per 3 kg of m i l k f o r cows y i e l d i n g over 25 kg o f milk per day and 1 kg per 4 kg f o r cows y i e l d i n g l e s s than 25 kg. Each cow r e c e i v e d 1 kg of - 20 -g r a i n at m i l k i n g time and the remainder was given i n equal a amounts a t the d i f f e r e n t f e e d i n g times. Six g r a i n samples were ob t a i n e d at r e g u l a r i n t e r v a l s d u r i n g the f e e d i n g t r i a l . They were analyzed f o r dry matter by oven d r y i n g a t 60°C f o r 72 hours. T o t a l p r o t e i n , ash, ADF and l i g n i n were determined on the oven d r i e d sample. Since g r a i n come p o s i t i o n was known i t s energy content was c a l c u l a t e d u s i n g the NAS-NRC t a b l e s (1978). A l l the animals were weighed on three c o n s e c u t i v e days a t the beginning and end of each experimental p e r i o d t o get an estimate of t h e i r t r u e weight. Weighing was performed at 13.00 h. The net energy v a l u e of the body weight g a i n or l o s s was c a l c u l a t e d u s i n g the NRC recommendations (NAS-NRC 197 8). The m i l k y i e l d of the twelve cows was recorded at each m i l k i n g time. The average milk p r o d u c t i o n per day was c a l c u l a t e d on a weekly b a s i s . The 4% f a t - c o r r e c t e d milk (FCM) was o b t a i n e d u s i n g the f o l l o w i n g formula: FCM(kg) = M i l k ( k g ) * ( . 4 + . 1 5 * ( % f a t ) ) . S i m i l a r l y the amount of s o l i d s - c o r r e c t e d milk (SCM) was p r e d i c t e d (r=.99) by the eq u a t i o n : SCM(kg) = Milk(kg)*(.123*(%fat)+.0656*(%SNF)-.0752) ( T y r r e l l and Reid, 1965). M i l k samples of each animal were obtained from four c o n s e c u t i v e m i l k i n g s d u r i n g the t h i r d and l a s t week of each experimental p e r i o d and analyzed f o r f a t , p r o t e i n and l a c t o s e by IRMA (Infra-Red-Milk-Analyzer) at the P r o v i n c i a l D a i r y L a b o r a t o r y , BCMA, Burnaby. Percentage of s o l i d s - n o n - f a t (SNF) was c a l c u l a t e d i n the f o l l o w i n g way: - 21 -%SNF = % p r o t e i n + % l a c t o s e + .75(ash). Rumen samples were taken v i a stomach tube from each cow at 8.00 h once d u r i n g the f o u r t h and l a s t week of each experimental p e r i o d . Samples of approximately 2 00 ml were c o l l e c t e d . The pH of the ruminal f l u i d was determined immediately a f t e r the samples had been obtained. A small sample was f r o z e n f o r f u r t h e r a n a l y s i s . A q u a l i t a t i v e measurement of the v o l a t i l e f a t t y a c i d s i n the rumen f l u i d was obtained by g a s - l i q u i d chromatography (Erwin e t a l . , 1961). Each f e e d i n g day s t a r t e d with the 10.00 h f e e d i n g . Every morning at 7.30 h the cows were locked out of the f e e d i n g area, the mangers cleaned.and-'the uneonsumed s i l a g e and g r a i n were weighed f o r each cow. Feed i n t a k e was recorded d a i l y . S i l a g e was fed at a r a t e to ensure t h a t there was always about 10% feed r e s i d u e s . Based on the amount of weighback the next day's amount of s i l a g e was a d j u s t e d . At the 10.00 h f e e d i n g each cow r e c e i v e d 15 kg of s i l a g e and one t h i r d of i t s g r a i n r a t i o n . The remaining feed was kept ready i n buckets i n the barn f o r the other two fe e d i n g s . In the afternoon and i n the morning cows were f e d a f t e r m i l k i n g (14.30 h and 5.00 h ) . 3.7. D i g e s t i b i l i t y t r i a l Three cows from each group were subjected t o a 7-day t o t a l c o l l e c t i o n o f feces and u r i n e d u r i n g the second l a s t week of each experimental p e r i o d i n order to estimate the d i g e s t i b i l i t y of the r a t i o n . The cows f o r the d i g e s t i o n t r i a l were s e l e c t e d on the b a s i s o f steady i n t a k e , m i l k a b i l i t y and s i z e of the - 22 -animal. One cow i n f i r s t l a c t a t i o n was i n c l u d e d i n each group. Both groups were kept as uniform as p o s s i b l e . The cows were moved to the stanchion barn a day b e f o r e the c o l l e c t i o n s t a r t e d and stayed there throughout the whole c o l l e c t i o n p e r i o d . A p l a s t i c web was glued on the cows' perineum to secure a hose to the v u l v a f o r the c o l l e c t i o n of u r i n e . At the a c t u a l s t a r t i n g time of the c o l l e c t i o n a rubber tube was sewn to the web. The p a r t t h a t was f i t t e d a g a i n s t the v u l v a was equipped with a wire frame which was adapted to the shape of the s u r f a c e of the v u l v a and a 5 cm long p l a s t i c tube was i n s e r t e d i n s i d e the hose to keep i t from c o l l a p s i n g so t h a t the u r i n e c o u l d flow away. Urine leakage was kept to a minimum. The u r i n e was conducted i n t o a covered m i l k i n g p a i l . About 10 cm 3 of formaldehyde (1/2 cm 3 per l i t r e of u r i n e ) were added to the u r i n e r e c e p t a c l e to prevent a l o s s of v o l a t i l e n i t r o g e n . Feces were c o l l e c t e d i n a c o l l e c t i o n box f i t t e d i n t o the g u t t e r behind each cow, then shoveled i n a l a r g e green p l a s t i c garbage bucket which was kept covered as w e l l . The c o l l e c t i o n days s t a r t e d always a t 9.00 h. The amounts of f e c e s were weighed, recorded and sampled d a i l y . A 500 g feces sample was o b t a i n e d d a i l y from each cow, put i n an aluminum t r a y and f r o z e n immediately. The u r i n e samples were pooled per cow over the whole c o l l e c t i o n p e r i o d . The f e c a l samples were analyzed f o r dry matter by oven d r y i n g a t 65°C f o r 72 hours. The seven samples from each cow c o l l e c t i o n p e r i o d were ground, composited and analyzed i n d u p l i c a t e f o r t o t a l n i t r o g e n , ash, ADF, NDF - 23 -and l i g n i n . U r i n e was a n a l y z e d f o r t o t a l n i t r o g e n and d r y -m a t t e r was d e t e r m i n e d by o v e n d r y i n g a 30 g s a m p l e a t 6 0°C f o r 5 0 h o u r s . B o t h n i t r o g e n and d r y m a t t e r d e t e r m i n a t i o n w e r e c a r r i e d o u t i n d u p l i c a t e . The f e e d i n g s c h e d u l e ~ f o r t h e cows on d i g e s t i o n was i d e n t i c a l t o t h e o t h e r cows'. T h e s e cows w e r e m i l k e d i n t h e i r s t a n c h i o n s . I n t h e a f t e r n o o n and i n t h e m o r n i n g t h e y w e r e f e d a t m i l k i n g t o k e e p them d i s t r a c t e d . E a c h a n i m a l was a s s i g n e d a g i v e n q u a n t i t y o f f e e d a c c o r d i n g t o p r e v i o u s i n t a k e w h i c h was f e d e v e r y day d u r i n g t h e c o l l e c t i o n p e r i o d . The g r a i n r a t i o n r e m a i n e d t h e same as i n t h e week p r e c e d i n g t h e d i g e s t -i b i l i t y t r i a l . S c h n e i d e r a n d F l a t t (1975) s t r e s s e d t h e i m p o r -t a n c e o f r e g u l a r f e e d i n g . W e i g h b a c k was r e c o r d e d a s d u r i n g t h e w h o l e e x p e r i m e n t . D u r i n g t h e d i g e s t i o n t r i a l s w e i g h b a c k was a l s o s a m p l e d d a i l y f o r e a c h cow on c o l l e c t i o n and p o o l e d p e r t r e a t m e n t f o r t h e cows n o t on c o l l e c t i o n . W e i g h b a c k s a m p l e s w e r e t a k e n and a n a l y z e d f o r d r y m a t t e r by o v e n d r y i n g , f o r p r o t e i n , ADF, l i g n i n and a s h t o e v a l u a t e t h e s i l a g e a s f e d and t h e s i l a g e a s consumed. The a p p a r e n t d r y m a t t e r , p r o t e i n , o r g a n i c m a t t e r , a c i d d e t e r g e n t f i b e r a nd l i g n i n d i g e s t i b i l i t i e s o f t h e t o t a l r a t i o n w e r e c a l c u l a t e d . The a p p a r e n t d i g e s t i b i l i t y (D) o f t h e s i l a g e d r y m a t t e r and p r o t e i n was o b t a i n e d b y a s s i g n i n g a D - v a l u e of-75% f o r t h e g r a i n . - 24 -3.8. Experimental design and s t a t i s t i c a l a n a l y s i s The experiment was planned and analyzed u s i n g a c r o s s -over design (Cochran and Cox, 1966), which means t h a t a se-quence of treatments was a d m i n i s t e r e d to each animal. A l l o b s e r v a t i o n s taken d u r i n g the f e e d i n g and d i g e s t i b i l i t y t r i a l were su b j e c t e d to an a n a l y s i s of v a r i a n c e (ANOVA), wi t h v a r i a n c e being p a r t i o n e d i n t o t h a t a s s o c i a t e d with cows, pe r i o d s and treatments. The a d d i t i v e t r e a t e d s i l a g e was to be compared wi t h the c o n t r o l s i l a g e . The second p e r i o d gave a r e p l i c a t e of each cow and i n d i c a t e d the change i n l e v e l of i n t a k e and p r o d u c t i o n performance. The model used removed the d i f f e r e n c e between the two experimental p e r i o d s from the e r r o r as an average of a l l cows. The i n c l u s i o n of the cows i n the model was c o n s i d e r e d to be important to remove the v a r i a b i l i t y among animals. The d e s i g n d i d not allow f o r a group e f f e c t to be t e s t e d , f o r groups were completely confounded w i t h cows. The f o l l o w i n g s t a t i s t i -c a l model was used f o r the a n a l y s i s of the f e e d i n g t r i a l . Source of v a r i a t i o n Degrees of freedom Cows 11 P e r i o d s 1 Treatments 1 E r r o r 10 T o t a l 2 3 C o v a r i a b l e s were added to the above model f o r the analyses of c o v a r i a n c e which were performed on some v a r i a b l e s . - 25 -F o r t h e d i g e s t i b i l i t y t r i a l 5 d e g r e e s o f f r e e d o m w e r e a l l o t t e d f o r co w s , one e a c h f o r p e r i o d a n d t r e a t m e n t and f o u r f o r t h e e x p e r i m e n t a l e r r o r . The d a t a on s i l a g e c o m p o s i t i o n a s w e l l as t h e s i l a g e e f f l u e n t was a n a l y z e d u s i n g a o n e - w a y - c l a s s i f i c a t i o n , t h e m a i n c l a s s i f i c a t i o n b e i n g t r e a t m e n t s . The number o f o b s e r -v a t i o n s p e r t r e a t m e n t was 14 f o r t h e s i l a g e c o m p o s i t i o n d a t a and 30 f o r t h e s i l a g e e f f l u e n t d a t a . The d i f f e r e n c e s b e t w e e n cows, p e r i o d s and t r e a t m e n t s w e re t e s t e d a t a s i g n i f i c a n c e l e v e l o f 5% t h r o u g h o u t t h e w h o l e e x p e r i m e n t . The f o l l o w i n g p a c k a g e p r o g r a m s were u s e d f o r t h e d i f f e r e n t s t a t i s t i c a l a n a l y s e s : UBC MFAV ( A u g u s t 1 9 7 8 ) , UBC BMD10V (November 1975) and UBC TRP ( O c t o b e r 1 9 7 8 ) . - 26 -4. RESULTS 4.1. F e e d s 4.1.1. F o r a g e i n T h e r e was o n l y 200 k g d i f f e r e n c e i n t h e amount o f t o t a l f o r a g e i n t h e two s i l o s ( T a b l e 2). The a v e r a g e d r y m a t t e r c o n t e n t o f 19.11% f o r t h e c o n t r o l and 18.94% f o r t h e t r e a t e d s i l a g e r e s u l t e d i n a s m a l l d i f f e r e n c e o f t o t a l d r y m a t t e r e n s i l e d . A l l t h e f o r a g e h a r v e s t e d on t h e f i r s t d a y o f e n s i l i n g h a d a d r y m a t t e r c o n t e n t o f s l i g h t l y o v e r 15% due t o s h o r t w i l t i n g t i m e , w e t g r o u n d and l i t t l e s u n s h i n e . On t h e s e c o n d d a y t h e d r y m a t t e r c o n t e n t was h i g h e r and r e a c h e d a b o u t 24% f o r a few l o a d s . The f o r a g e e n s i l e d on t h e l a s t d a y , w h i c h was c u t t h a t d a y , showed an a v e r a g e d r y m a t t e r c o n t e n t o f 17.5%. T a b l e 2: L o c a t i o n and amount o f f o r a g e and d r y m a t t e r h a r v e s t e d on d i f f e r e n t d a y s . C o n t r o l S i l o N u t r o L a c - S i l o F o r a g e (kg) DM (kg) F o r a g e (kg) DM (kg) May 17, 78 8728 1346 . 4 10890 1676 . 5 May 18, 78 22590 4780. 20354 4417. 2 May 19, 78 8965 1574. 5 9240 1574. 2 F i e l d 1 28574 5523. 5 27457 5271. 2 F i e l d 9 11709 2177. 4 13027 2396. 7 T o t a l 40283 7700. 9 40484 7667. 9 - 27 -A b o u t 70% o f t h e f o r a g e o r i g i n a t e d f r o m f i e l d 1 and t h e r e m a i n d e r f r o m f i e l d 9. T h e r m o c o u p l e s w e r e i n s e r t e d i n b o t h s i l o s a f t e r 13 and 23 t o n n e s o f wet m a t e r i a l . The a v e r a g e p r o t e i n c o n t e n t o f 14.32% and 14.47% f o r c o n t r o l and t r e a t e d , r e s p e c t i v e l y , was v e r y c l o s e ( T a b l e 3) b u t t h e r e was a b i g d i f f e r e n c e i n t h e p r o t e i n c o n t e n t b e t w e e n t h e two f i e l d s . The m a t u r e g r a s s o f f i e l d 1 h a d a p r o t e i n c o n t e n t o f 11.8% w h i l e t h e y o u n g g r a s s o f f i e l d 9 had a p r o t e i n c o n t e n t o f 17.4%. A s h , ADF and ADL were v e r y s i m i l a r f o r b o t h s i l o s , t h e means b e i n g 8.8, 37.4 and 5.4%. On a m o i s t u r e f r e e b a s i s t h e t r e a t e d s i l a g e c o n t a i n e d 2.64 k g o f t h e a d d i t i v e N u t r o L a c S i l a - A i d p e r t o n n e DM. T a b l e 3: C o m p o s i t i o n o f t h e f o r a g e s e n s i l e d . DM CP A s h ADF ADL Q, O o "o o, "o Q. "O o. N u t r o L a c 18. 94 14. 47 8.9 37.5 5.5 C o n t r o l 19. 11 14. 32 8.7 37.3 5.3 4.1.2. S i l a g e o u t The amount o f f o r a g e removed f r o m t h e c o n t r o l a n d t h e N u t r o L a c s i l o was 31,400 a n d 30,800 k g , r e s p e c t i v e l y . A t t h e t i m e t h e s i l o s w e r e o p e n e d a t o p l a y e r o f a b o u t 500 k g was d i s c a r d e d f r o m e a c h s i l o . A s t h e s i l o s w e r e e m p t i e d c Q n t i n -- - u o u s l y - t h e r e was minimum s p o i l a g e " . . D a i l y s i l a g e f o r k e d o u t i n e x c e s s warmed up f o r 1 week f o r t r e a t e d and 5 weeks f o r c o n t r o l s i l a g e due t o e x p o s u r e t o a i r i n d i c a t i n g a d i f f e r e n c e i n r a t e o f f e r m e n t a t i o n . - 28 -T a b l e 4:. C o m p o s i t i o n o f s i l a g e s and c o n c e n t r a t e . PH DM CP S o l r v A s h ADF NDF ADL DE ."5 • Q. *o N % o. "o Q, Q. "O o "6 MJ/kg N u t r o L a c 4.63 22.83 13.22 8.58 9.30 43.35 82.53 6 . 06 12.26 C o n t r o l 4.77 23.85 13.00 7. 70 8 . 90 40.20 77. 80 6 . 04 13.01 G r a i n — 89.50 22.24 — 8.32 6. 40 — 1. 32 14. 39 The a v e r a g e d r y m a t t e r c o n t e n t o f t h e s i l a g e s a s r e m o v e d f r o m t h e s i l o s d e t e r m i n e d by t o l u e n e d i s t i l l a t i o n was 2 3 . 8 % and 2 2.8% f o r t h e c o n t r o l a n d N u t r o L a c s i l a g e , r e s p e c t i v e l y ( T a b l e 4 ) . T o t a l p r o t e i n c o n t e n t was 13.0 and 13.2% f o r t h e c o n t r o l and t r e a t e d s i l a g e , r e s p e c t i v e l y . The p r o p o r t i o n o f s o l u b l e n i t r o g e n was h i g h e r i n t h e a d d i t i v e t r e a t e d s i l a g e v/here i t a c c o u n t e d f o r 6 4.9% o f t h e t o t a l N c o m p a r e d t o 5 9 . 2 % i n t h e c o n t r o l . The a s h c o n t e n t o f 9.3% i n t h e N u t r o L a c s i l a g e was h i g h e r t h a n t h e 8.9% o f t h e c o n t r o l . I n t h e t r e a t e d s i l a g e 43.4, 82.5 a n d 6.1% o f t h e d r y m a t t e r a c c o u n t e d f o r ADF, NDF and l i g n i n , c o m p a r e d t o 4 0 . 2 , 77.8 and 6.0% i n t h e c o n t r o l . The pH o f t h e s i l a g e s i n c r e a s e d d u r i n g t h e c o u r s e o f t h e e x p e r i m e n t . The y o u n g g r a s s w h i c h was r e m o v e d i n t h e f i r s t weeks o f t h e f e e d i n g t r i a l showed a l o w e r pH t h a n t h e m a t u r e g r a s s . The pH v a l u e s o f t h e c o n t r o l s i l a g e r a n g e d f r o m 4.2 t o 5.2, c o m p a r e d t o a r a n g e b e t w e e n 4.0 and 5.0 i n t h e s i l a g e c o n t a i n i n g t h e i n o c u l u m . The a v e r a g e pH v a l u e f o r t h e c o n t r o l and t r e a t e d s i l a g e was 4.77 and 4.63. The c o n t e n t o f DM, ADF, s o l u b l e N (as p e r c e n t a g e o f t o t a l N) , -.ash and t h e pH v a l u e - 29 -were s i g n i f i c a n t l y d i f f e r e n t b e t w e e n t h e t r e a t m e n t s b a s e d on t h e ANOVA p e r f o r m e d on t h e w e e k l y f e e d a n a l y s i s . The c a l c u l a t e d c o n t e n t o f d i g e s t i b l e e n e r g y was 12.26 and 13.01 MJ p e r k g DM f o r t h e t r e a t e d and c o n t r o l s i l a g e . D r y m a t t e r c o n t e n t o b t a i n e d b y o v e n d r y i n g and t o l u e n e d i s t i l l a t i o n showed an i n c r e a s e o f 17.8% f o r t h e c o n t r o l and 16.4% f o r t h e N u t r o L a c s i l a g e e x p r e s s e d i n p e r c e n t o f t h e o v e n d r y m a t t e r ( T a b l e 5). I n a b s o l u t e f i g u r e s t h e c o n t r o l s i l a g e h a d an o v e n d r y m a t t e r o f 21.2% a n d a t o l u e n e d r y m a t t e r o f 25.0% c o m p a r e d t o 20.6% and 23.9% f o r t h e t r e a t e d s i l a g e . The c o e f f i c e n t o f c o r r e l a t i o n b e t w e e n o v e n and t o l u e n e d r y m a t t e r was .90 f o r t h e c o n t r o l and .92 f o r t h e N u t r o L a c s i l a g e . T a b l e ;5: C o m p a r i s o n b e t w e e n o v e n and t o l u e n e d r y m a t t e r (9 s a m p l e s p e r t r e a t m e n t ) . o v e n DM % N u t r o L a c 2 0.56 C o n t r o l 21.21 4.1.3. C o m p a r i s o n o f s i l a g e and w e i g h b a c k The s i l a g e a s f e d and t h e s i l a g e as consumed was a l m o s t i d e n t i c a l . The d r y m a t t e r c o n t e n t o f t h e w e i g h b a c k , w h i c h r, c o u l d be k e p t a t 10% o f t h e i n t a k e was on t h e a v e r a g e 1.5 p e r c e n t u n i t s h i g h e r t h a n i n t h e o r i g i n a l s i l a g e . T a k i n g t h a t f i g u r e i n t o a c c o u n t t h e c a l c u l a t e d d a i l y d r y m a t t e r i n t a k e w o u l d be o v e r e s t i m a t e d b y 7 0 g. The p r o t e i n c o n t e n t was h a l f a p e r c e n t u n i t l o w e r a n d t h e a s h c o n t e n t one p e r c e n t h i g h e r . t o l u e n e d i f f % DM % 23. 93 24.99 o v e n DM 16.4 17.8. r - v a l u e . 92 . 90 - 30 -A c i d d e t e r g e n t f i b e r and l i g n i n i n c r e a s e d l e s s t h a n h a l f a p e r c e n t u n i t . 4.1.4. G r a i n m i x t u r e The c o n c e n t r a t e f e d d u r i n g t h e e x p e r i m e n t a t an a v e r a g e r a t e o f 1 k g p e r 3.5 k g o f m i l k c o n t a i n e d 2 2 . 2 % c r u d e p r o t e i n and h a d a d i g e s t i b l e e n e r g y c o n t e n t o f 14.4 MJ p e r k g DM ( T a b l e 4 ) . The i n g r e d i e n t s o f t h e g r a i n m i x a r e t a b u l a t e d i n t a b l e 6. T a b l e 6: I n g r e d i e n t s o f c o n c e n t r a t e m i x t u r e . I n g r e d i e n t Q. *o Wheat 30 B a r l e y 31 S o y b e a n m e a l 20 R a p e s e e d m e a l 10 M o l a s s e s 4 S a l t 1 D i c a l c i u m p h o s p h a t e 3 M i n e r a l - V i t a m i n M i x 1 4.1.5. D e g r e e o f p r e s e r v a t i o n I t i s w e l l known t h a t l o s s e s o c c u r d u r i n g t h e e n s i l i n g p r o c e s s . T h e r e f o r e , t h e w e i g h t o f t h e f o r a g e p l a c e d i n t h e s i l o s m ust be c o m p a r e d w i t h t h e w e i g h t o f t h e f e r m e n t e d s i l a g e r e m o v e d . By c o m p a r i n g t h e s e two w e i g h t m e a s u r e m e n t s t h e s u c c e s s of the silage making was estimated. The recovery of d i f - J ferent:-.feed components as • a percentage of the. ensiled material-i s l i s t e d i n tables 7 and 8. The protein recovery was lowest.' Most recoveries were i n excess of what was ensiled, which indicates that an error occured somewhere (discussed l a t e r ) . Table 7: Percent recoveries of feed components i n eff l u e n t and silage (NutroLac Silage). DM CP Ash ADF ADL Ensiled 100 100 100 100 100 Effluent 2.5 4.2 8.4 Silage 91.9 84.0 95.5 106.2 101.3 Percent recovered 94.4 88.2 103.9 106.2 101.3 Table 8: Percent recoveries of feed components i n e f f l u e n t and silage (Control Silage). DM CP Ash ADF ADL Ensiled 100 100 100 100 100 Effl u e n t 1.5 2.3 . 5.6 Silage 97.5 88.5 99.8 105.1 111.1 Percent recovered 99.0 90,8 105.4 105.1 111.1 - 32 -4.2. E f f l u e n t l o s s a n d s i l a g e t e m p e r a t u r e 4.2.1. S i l a g e e f f l u e n t The r a t e o f s e e p a g e f l o w was s i g n i f i c a n t l y g r e a t e r f o r t h e N u t r o L a c j s i l a g e t h a n f o r t h e c o n t r o l ( F i g 1 ) . The a v e r a g e d a i l y f l u i d l o s s o v e r a 30-day p e r i o d was 149.5 and 83.0 k g f o r t h e t r e a t e d and t h e c o n t r o l s i l a g e . On t h e l a s t d a y o f m e a s u r e m e n t t h e e f f l u e n t h a d d e c r e a s e d t o 5.4 k g f o r t h e c o n t r o l a n d 22.6 k g f o r t h e t r e a t e d s i l a g e . The t r e a t e d s i l a g e c o n -t i n u e d l o s i n g e f f l u e n t f o r a n o t h e r month. F i g u r e 1: E f f e c t o f t r e a t m e n t on d a i l y e f f l u e n t l o s s . E f f l u e n t (kg) 0 4 8 12 16 20 24 28 ( d a y s ) - 33 -The a v e r a g e d a i l y d r y m a t t e r p e r c e n t a g e o f t h e r u n - o f f o f b o t h s i l o s was v e r y c l o s e , 4.61% f o r t h e one c o n t a i n i n g t h e a d d i t i v e and 4.55% f o r t h e c o n t r o l ( T a b l e 9 ) . No a d j u s t -ment was made f o r t h e l o s s o f v o l a t i l e compounds. The w e i g h t e d d r y m a t t e r c o n t e n t was 4.2 8 a n d 4.44%. The d r y m a t t e r l o s s p e r day w h i c h was as s i g n i f i c a n t a s t h e f l u i d l o s s a v e r a g e d 6.4 and 3.7 k g f o r t h e t r e a t e d and c o n t r o l s i l a g e . The t o t a l l o s s o f d r y m a t t e r o v e r t h e 30-day p e r i o d amounted t o 192 and a n d 112 k g . The d a i l y c h a n g e i n DM l o s s v i a e f f l u e n t i s shown i n f i g u r e 2. T a b l e 9: E f f l u e n t c o m p o s i t i o n (%) and t o t a l l o s s (kg) d u r i n g t h e 30-day c o l l e c t i o n p e r i o d . N u t r o L a c C o n t r o l S i g n . pH 4.37 4.52 * DM (%) 4.61 4.55 ns CP (%) 1.02 1.0 ns A s h (% o f DM) 31.15 33.46 * N (% o f DM) 4.46 4.44 ns CP (% o f DM) 27.86 27.77 ns F l u i d l o s s (kg) 4485 2518 * DM (kg) 192.2 111.8 * A s h (kg) 57.7 37.3 * N (kg) 7.34 4.02 * CP (kg) 45.9 25.1 * * : s i g n i f i c a n t d i f f e r e n c e b e t w e e n t r e a t m e n t s a t P ^ .05 ns n o t s i g n i f i c a n t - 34 -The a s h c o n t e n t o f t h e s e e p a g e d r y m a t t e r was s i g n i f i c a n t l y g r e a t e r f o r t h e r u n - o f f o f t h e c o n t r o l s i l a g e c o m p a r e d t o t h e r u n - o f f o f t h e t r e a t e d s i l a g e w h i l e t h e a s h - l o s s p e r d a y was s i g n i f i c a n t l y g r e a t e r f o r t h e l a t t e r . P r o t e i n p e r c e n t a g e o f t h e f l u i d l o s t was i d e n t i c a l f o r b o t h s i l o s , b a s e d on t h e e f f l u e n t d r y m a t t e r i t was g r e a t e r i n t h e s e e p a g e o f t h e N u t r o L a c s i l a g e . The d a i l y l o s s o f ~-p r o t e i n was s i g n i f i c a n t l y h i g h e r f o r t h e t r e a t e d s i l a g e . The a v e r a g e d a i l y p r o t e i n l o s s v i a e f f l u e n t was 837 and 1530 g f r o m t h e c o n t r o l a n d t r e a t e d s i l a g e . f i g u r e 3 i l l u s t r a t e s t h e d a i l y c h a n g e i n p r o t e i n l o s s v i a e f f l u e n t . F i g u r e 2: D a i l y l o s s o f DM v i a e f f l u e n t . DM l o s s (kg) 4 40. 2 4 ' 32 -16-^•time 0 4 8 12 16 20 2 4 - 35 -F i g u r e 3: D a i l y l o s s of p r o t e i n v i a e f f l u e n t . CP l o s s (kg) I 1 1 1 —T j —r-= ~ i " ~> t ime 0 4 3 12 16 20 24 28 (days) The average pH was higher a t P<. 05 f o r the c o n t r o l s i l a g e e f f l u e n t v/hich had a pH of 4.52 compared to 4.37 i n the NutroLac s i l a g e e f f l u e n t . The e f f l u e n t pH decreased t o 4.0 f o r both s i l a g e s d u r i n g the f i r s t seven days of c o l l e c t i o n , then i n c r e a s e d u n t i l the end of the c o l l e c t i o n p e r i o d at which time pH values of 4.8 and 5.0 were recorded f o r t r e a t e d and c o n t r o l s i l a g e . Table 10 and 11 i n d i c a t e t h a t p r o t e i n content and pH are h i g h l y c o r r e l a t e d w i t h time. The p r o t e i n content of the e f -f l u e n t dry matter of both s i l o s i n c r e a s e d from about 20 t o 35% d u r i n g the c o l l e c t i o n p e r i o d whereas the pH i n c r e a s e d from 4 to 5. The ash content i n c r e a s e d more i n the r u n - o f f of the - 36 -Table 10: C o r r e l a t i o n s between e f f l u e n t parameters (NutroLac s i l a g e , 30 p a i r e d o b s e r v a t i o n s ) Days PH DM Q. O Ash o, "o CP F l u i d % l o s s DM l o s s Ash l o s s Days 1.0 pH . 87 1.0 DM % - .29 -.04 1.0 •. Ash % .81 . 85 -.08 1.0 CP % . 95 .83 . 30 .76 1.0 F l u i d l o s s -.68 -.28 -.64 -.40 -.64:1.0 DM l o s s -.69 -.29 -.56 -.42 -.65 .99 1.0 Ash l o s s -.69 -.29 -.57 -.42 -.65 .99 1.0 1.0 CP l o s s -.69 -.30 -.51 -.44 -.63 .98 1.0 1.0 Tab l e 11: C o r r e l a t i o n s between e f f l u e n t parameters (Control s i l a g e , 30 p a i r e d o b s e r v a t i o n s ) Days PH DM Q. "6 Ash o "o CP Fl'uid % l o s s DM Ash l o s s l o s s Days 1.0 PH .90 1.0 DM % -.16 -.34 1.0 Ash % . 37 . .56 -.35 1.0 Prot % . 96 .82 -.08 .24 1.0 F l u i d l o s s - .65 -.35 -.13 -.01 -.70 1.0 DM l o s s -.63 -.36 . 03 -.06 -.67 .98 1.0 Ash l o s s -.63 -.35 . 00 -.03 -.68 .98 1.0 1.0 Prot l o s s -.64 - . 39 . 08 -.09 -.67 .96 1.0 .99 C o r r e l a t i o n s are. s i g n i f i c a n t a t P g . 05 i f r ^ . 3 6 - 37 -N u t r o L a c s i l a g e c o m p a r e d t o t h e r u n - o f f o f t h e c o n t r o l s i l a g e . P r o t e i n and a s h t o g e t h e r a c c o u n t e d f o r 50% o f t h e e f f l u e n t d r y m a t t e r i n t h e b e g i n n i n g o f t h e c o l l e c t i o n p e r i o d and f o r 70% t o w a r d s t h e e n d . The d r y m a t t e r c o n t e n t r o s e i n t h e s e e -p a ge o f t h e c o n t r o l s i l a g e . . ( F i g 4 ) . The pH had a h i g h c o r r e -l a t i o n w i t h p r o t e i n a n d a s h c o n t e n t . A l t h o u g h p r o t e i n and a s h c o n t e n t w e r e n o t r e l a t e d t o d r y m a t t e r c o n t e n t t h e r e w a s ; a s i g n i f i c a n t c o r r e l a t i o n b e t w e e n d r y m a t t e r , a s h and p r o t e i n l o s s ( r > , 99) . The t r e a t e d s i l a g e l o s t 13.7% o f i t s m o i s t u r e and 2.51% o f i t s d r y m a t t e r v i a r u n - o f f w h i l e t h e c o n t r o l s i l a g e l o s t 7.7% o f i t s m o i s t u r e a nd 1.46% o f i t s d r y m a t t e r . The s e e p a g e l o s s o f t h e N u t r o L a c s i l a g e was a l m o s t d o u b l e f o r t h e 30-day c o l l e c t i o n p e r i o d c o m p a r e d t o t h e c o n t r o l s i l a g e a l t h o u g h t h e F i g u r e 4: Change i n e f f l u e n t DM w i t h t i m e . DM (%) t i m e ( d a y s ) - 38 -g r a s s e n s i l e d was o f s i m i l a r d r y m a t t e r c o n t e n t f o r b o t h s i l a g e s . P r o t e i n and a s h l o s t as e f f l u e n t amounted t o 4.15 and 8.43% o f t h e e n s i l e d p r o t e i n a nd a s h f o r t h e N u t r o L a c s i l a g e c o m p a r e d t o a l o s s o f 2.28 a n d 5.58% f o r t h e c o n t r o l . A b o u t 73 a n d 82% o f t h e m e a s u r e d r u n - o f f o c c u r e d i n t h e f i r s t s e v e n ' d a y s a f t e r e n s i l i n g f o r t h e c o n t r o l and t r e a t e d s i l a g e . O v e r t h e same t i m e t h e l o s s o f p r o t e i n a n d a s h v i a s e e p a g e amounted t o 66 and 70% f o r t h e t r e a t e d s i l a g e a nd 77 and 8 1 % f o r t h e c o n t r o l . 4.2.2. S i l a g e t e m p e r a t u r e The d i f f e r e n c e i n t e m p e r a t u r e b e t w e e n t h e two s i l o s was a l w a y s a b o u t one d e g r e e , t h e t e m p e r a t u r e s f o r t h e s i l a g e c o n -t a i n i n g t h e a d d i t i v e b e i n g h i g h e r ( F i g 5 ) . The t e m p e r a t u r e s F i g u r e 5: T r e a t m e n t a n d s i l a g e t e m p e r a t u r e . Temp. (°C) 1i 1 1 1 1 1 1 1 1 1— 0 4 8 12 16 20 24 28 32 36 t i m e ( d a y s ) - 39 -a t t h e u p p e r t h e r m o c o u p l e w e r e 21.6 a n d 2 2.2°c f o r c o n t r o l a n d t r e a t e d s i l a g e on t h e f i r s t d a y . The c o n t r o l s i l a g e r e a c h e d i t s p e a k t e m p e r a t u r e o f 2 9.1°C on t h e n i n t h d a y , t h e N u t r o L a c s i l a g e p e a k e d on t h e same day a t 30.3°C. Then b o t h s i l a g e t e m p e r a t u r e s d e c l i n e d a t a b o u t t h e same r a t e . A t t h e l o w e r t h e r m o c o u p l e s t h e t e m p e r a t u r e s t a r t e d a t a b o u t 16.5°C i n r b o t h s i l o s . The t e m p e r a t u r e o f t h e c o n t r o l s i l a g e r o s e q u i t e r a p i d l y i n t h e f i r s t t e n d a y s up t o 2 3.3°C, t h e n s t a y e d o v e r 2 3.5°C f o r t h r e e w e e k s . I t r e a c h e d t h e peak o f 2 4.0°C on d a y 17. The lower-, t h e r m o c o u p l e o f t h e N u t r o L a c s i l o s t o p p e d f u n c t i o n i n g a f t e r 12 d a y s . The c a b l e o f t h e t h e r m o c o u p l e was p u l l e d a p a r t due t o t h e s e t t l i n g a c t i o n o f t h e e n s i l a g e . T he t e m p e r a t u r e r e c o r d i n g s r o s e u n t i l d a y 10 when i t r e a c h e d 24.6°C. The l a s t two r e c o r d i n g s w e r e 2 4.1 a n d 2 4.3°C. i t i s p r o b a b l e t h a t t h e t e m p e r a t u r e h a d r e a c h e d i t s p e a k a n d s t a r t e d t o l e v e l o f f . A f t e r 2.5 months a t e m p e r a t u r e o f 22.6°C was r e c o r d e d f o r t h e t r e a t e d s i l a g e c o m p a r e d t o t e m p e r a t u r e s o f 21.6 and 2 0.8°C a t t h e u p p e r a n d l o w e r t h e r m o c o u p l e f o r t h e c o n t r o l . - 40 -4.3. F e e d i n g T r i a l The ANOVA p e r f o r m e d on a l l t h e p r o d u c t i o n v a r i a b l e s d i d n o t show a s i g n i f i c a n t d i f f e r e n c e b e t w e e n t h e two t r e a t m e n t s f o r any o f t h e v a r i a b l e s ( T a b l e 12).^ F o r m o s t v a r i a b l e s a s i g n i f i c a n t d i f f e r e n c e was f o u n d b e t w e e n t h e two p e r i o d s ( T a b l e 1 3 ) . The a n i m a l e f f e c t was s i g n i f i c a n t f o r most . r e -p r o d u c t i o n f a c t o r s . 4.3.1. I n t a k e On a wet b a s i s cows f e d N u t r o L a c : , s i l a g e consumed d a i l y 1.9 k g more f o r a g e ( T a b l e 1 2 ) . F o r a g e , g r a i n and t o t a l DM i n t a k e was v e r y s i m i l a r f o r b o t h t r e a t m e n t s , t h e a v e r a g e v a l u e s f o r t h e c o n t r o l s i l a g e a l w a y s b e i n g s l i g h t l y h i g h e r . The a n i m a l s on t h e N u t r o L a c S i l a - A i d t r e a t m e n t consumed 10.1 k g o f f o r a g e d a i l y c o m p a r e d t o 10.2 k g f o r t h e c o n t r o l . The g r a i n was r e a d i l y consumed by m o s t o f t h e cows. I t t o o k t h e two o l d e s t a n i m a l s some t i m e t o g e t a d j u s t e d t o a h i g h c o n c e n t r a t e r a t i o n . The g r a i n i n t a k e was 7.8 and 8.2 k g p e r d a y . The i n t a k e c h a n g e d s i g n i f i c a n t l y f r o m p e r i o d I t o p e r i o d I I ( T a b l e 1 3 ) . The f o r a g e i n t a k e i n c r e a s e d f r o m 9.4 k g t o 10.8 k g , w h e r e a s ' t h e g r a i n c o n s u m p t i o n d r o p p e d t o a l a r g e r e x t e n t f r o m 9.3 k g t o 6.6 k g p e r d a y . The t o t a l DM i n t a k e a v e r a g e d f o r t h e w h o l e e x p e r i m e n t a l ••period was 18.1 k g . The i n c r e a s e i n f o r a g e i n t a k e p e r week i s i l l u s t r a t e d i n f i g u r e 6 f o r b o t h s i l a g e s . The cows a s s i g n e d t o t h e C o n t r o l - N u t r o L a c s e q u e n c e consumed more s i l a g e i n b o t h p e r i o d s . - 41 -Table 12: E f f e c t of treatment on i n t a k e , body weight change and milk performance. NutroLac S i l a g e C o n t r o l S i l a g e SE of mean F-va] Forage i n t . ( k g ) 43 . 3 41.4 3.16 3. 24 Fo r . : DM i n t . ( k g ) 10 . 08 10 .15 .78 • 08 Gr a i n i n t . ( k g ) 7.80 '8:16 1.24 1. 70 T o t a l DM i n t . 17.88 18.31 .80 • 96 Forage i n t . (%BW) 1.78 1.80 .15 12 T o t a l i n t . (%BW) 3.15 3.20 .12 • 38 BWC/period (kg) 3. 67 -5.58 7.96 1. 57 BWC/period (MJ NE) 83.51 -110.80 167.=06 1. 55 M i l k (kg) 27.7 28.4 3.51 1. 63 F a t (%) 3.29 3.30 .16 • 04 Prot (%) 2.86 2.85 . 07 • 20 L a c t (%) 4.81 4.84 . 05 1. 52 SNF (%) 8.42 8.43 . 09 . 04 FCM (kg) 24.3 25.1 2.60 2. 23 SCM (kg) 2 4/0 24.9 2.68 2 . 84 F a t (kg) .88 .92 . 08 1. 37 Prot (kg) .79 . 81 .10 1. 59 L a c t (kg) 1.33 1.38 . 18 3. 09 SNF (kg) 2.33 2.40 .30 2. 52 FCM/DM (kg) 2.58 2.58 .49 00 No v a r i a b l e s i n above t a b l e were s i g n i f i c a n t l y d i f f e r e n t between treatments a t a p r o b a b i l i t y l e v e l of 5%. - 42 -Table 13: E f f e c t of p e r i o d on i n t a k e , body weight change and milk performance and o v e r a l l mean. P e r i o d SE . O v e r a l l I II Mean xc3n' mean Forage i n t . ( k g ) 39. 82 44 .87 2 . 94 * 42. 35 For.DM i n t . ( k g ) 9.43 10 . 80 .72 * 10 . 12 G r a i n i n t . ( k g ) 9. 32 6 .64 1 .10 * 7. 98 T o t a l DM i n t . ( k g ) 18.75 17 . 44 .76 * 18. 10 Forage int.(%BW) 1.68 1 .91 .14 * 1. 79 T o t a l int.(%BW) 3.27 3 .08 . 11 ns 3. 18 BWC/period (kg) 5.58 -7 .50 7 .71 ns 96 BWC/period (MJ)NE) 124.14 -151 .42 161 . 80 ns -13. 65 M i l k (kg) 31.91 24 .10 3 . 09 * 28. 01 Fat (%) 3.16 3 .43 . 15 * 3. 30 Pr o t •(%) 2.83 2 .88 . 07 ns 2. 86 L a c t (%) 4.90 4 .74 .04 * 4. 82 SNF ( (%) 8.48 8 .37 .08 ns 8. 42 FCM (kg) 27.54 21 . 86 2 . 301 * 24. 70 SCM (kg) 27.46 21 . 48 2 . 37 * 24. 47 Fat (kg) .98 .82 . 08 * • 90 Prot (kg) .90 .70 .09 * • 80 La c t (kg) 1.56 1 .15 . 15 * 1. 36 SNF (kg) 2.70 2 . 02 .26 * 2 . 36 FCM/For.DM (kg) 3.08 2 .08 . 44 * 2 . 58 * s i g n i f i c a n t d i f f e r e n c e between p e r i o d s at P<.05 ns not s i g n i f i c a n t - 43 -F i g u r e 6: E f f e c t o f t r e a t m e n t on f o r a g e i n t a k e , ( kg DM/day) I n t a k e (kg) 12-10 8-N u t r o L a c s-| C o n t r o l i i i i i i r-^- t i m e 0 2 4 6 c h a n g e 2 4 6 (weeks) o v e r The d r a s t i c d r o p i n t h e f o r a g e i n t a k e f r o m week t h r e e t o f i v e was m a i n l y due t o a c h a n g e i n s i l a g e , c o m p o s i t i o n . I n t h e f i r s t few weeks t h e s i l a g e f r o m t h e y o u n g g r a s s h a r v e s t e d f r o m f i e l d 9 was f e d . The h o t w e a t h e r d u r i n g weeks 3-5 d i d n o t s t i m u l a t e f o r a g e i n t a k e e i t h e r . W e e k l y i n t a k e o f f o r a g e a n d t o t a l DM i n t a k e a v e r a g e d o v e r a l l cows i s d e p i c t e d i n f i g u r e 7. The f o r a g e DM i n t a k e i n ^ c r e a s e d w i t h some f l u c t u a t i o n s r o u g h l y f r o m 8.5 t o 11 k g . I n c o n t r a s t t h e g r a i n i n t a k e d r o p p e d f r o m 10 t o 6 k g . The t o t a l d r y m a t t e r i n t a k e p e a k e d i n t h e t h i r d week o f p e r i o d I a t 19.6 k g and t h e n d e c r e a s e d t o 16.9 k g i n t h e l a s t week o f t h e e x p e r i m e n t . F o r a g e i n t a k e a s a p e r c e n t a g e 6f t o t a l d r y m a t t e r i n t a k e a c c o u n t e d f o r 45.8% a t t h e v e r y b e g i n n i n g o f - 44 -F i g u r e 7: A v e r a g e f o r a g e and t o t a l DM i n t a k e o f a l l cows. I n t a k e (kg) \ 20 16 . 12 -4 -- i 1 r 6 c h a n g e 2 o v e r T o t a l DM F o r a g e DM I > t i m e 6 (weeks) t h e e x p e r i m e n t c o m p a r e d t o 64.6% a t t h e end. 4.3.2. Body w e i g h t c h a n g e The mean body w e i g h t a t t h e b e g i n n i n g o f t h e t r i a l was 577 k g . The cows g a i n e d on t h e a v e r a g e 5.6 k g i n p e r i o d I and l o s t 7.5 k g i n p e r i o d I I , t h e f i n a l w e i g h t b e i n g 575 k g . N e i t h e r t h e t r e a t m e n t , p e r i o d n o r t h e a n i m a l e f f e c t was s i g n i f i c a n t . The cows t h a t w e r e f e d t h e s i l a g e c o n t a i n i n g t h e a d d i t i v e g a i n e d 7.3 k g and 0.0 k g i n p e r i o d I and I I c o m p a r e d t o a g a i n o f 3.8 k g i n p e r i o d I a n d a l o s s o f 15.0 k g i n p e r i o d I I f o r t h e cows on c o n t r o l s i l a g e . The mean w e i g h t - 45 -l o s s was r e d u c e d b y t h e two y o u n g e s t a n i m a l s w h i c h g a i n e d 12.5 k g p e r p e r i o d . A c c o r d i n g l y , f o r a g e a n d t o t a l d r y m a t t e r i n t a k e e x p r e s s e d as a p e r c e n t o f b o d y w e i g h t was n o t s i g n i -f i c a n t l y d i f f e r e n t b e t w e e n t h e t r e a t m e n t s . The f o r a g e i n t a k e as a p e r c e n t o f t h e b o d y w e i g h t was s i g n i f i c a n t l y h i g h e r i n t h e s e c o n d p e r i o d . The o v e r a l l mean f o r t h e f o r a g e and t o t a l DM i n t a k e was 1.8% a n d 3.2% o f t h e body w e i g h t . 4.3.3. M i l k y i e l d and c o m p o s i t i o n A s p r e v i o u s l y m e n t i o n e d t h e r e n w a s a l s o no s i g n i f i c a n t d i f f e r e n c e b e t w e e n t r e a t m e n t s f o r t h e m i l k y i e l d a n d m i l k c o m p o n e n t s ( T a b l e 12). The cows on N u t r o L a c S i l a - A i d s i l a g e y i e l d e d 27.7 k g o f m i l k ; t h e cows on t h e c o n t r o l s i l a g e p r o -d u c e d 2 8.4 k g d a i l y . The ANOVA showed t h a t t h e c o n t e n t o f m i l k s o l i d s was t h e same f o r b o t h t r e a t m e n t s ; b u t t e r f a t 3.3%, p r o t e i n 2.9%, l a c t o s e 4.8% and s o l i d s - n o n - f a t 8.4%. The a c t u a l f a t c o n t e n t o f a l l m i l k p r o d u c e d was 3.2%. The m i l k y i e l d a n d l a c t o s e c o n t e n t d r o p p e d s i g n i f i c a n t l y f r o m p e r i o d I t o p e r i o d II ( T a b l e 13). The m i l k y i e l d d r o p p e d f r o m 31.9 k g to!'24.1 k g a n d l a c t o s e c o n t e n t f r o m 4.9% t o 4.7%. The f a t c o n t e n t i n c r e a s e d s i g n i f i c a n t l y f r o m 3.2 t o 3.4%. The c o n t e n t o f p r o t e i n and s o l i d s - n o n - f a t d i d n o t c h a n g e s i g n i f i c a n t l y , t h e f o r m e r i n c r e a s i n g , t h e l a t t e r d e c r e a s i n g s l i g h t l y . The m i l k y i e l d a v e r a g e d o v e r b o t h p e r i o d s was 28.0 k g w i t h a b u t t e r -f a t c o n t e n t o f 3.3%, w h i c h y i e l d e d 2 4.7 k g FCM. The d a i l y SCM amounted t o 2 4.5 k g . The e f f e c t o f t r e a t m e n t on m i l k p r o d u c t i o n i s i l l u s t r a t e d i n f i g u r e 8. - 46 -F i g u r e 8: E f f e c t o f t r e a t m e n t o n m i l k p r o d u c t i o n , ( k g / d a y ) M i l k (kg) N u t r o L a c C o n t r o l , ±. t i m e (weeks) The t h e amount o f FCM p e r k g o f f o r a g e i n t a k e was e q u a l f o r b o t h t r e a t m e n t s w i t h 2.6 k g , b u t d e c r e a s e d s i g n i f i c a n t l y f r o m 3.1 k g i n p e r i o d I t o 2.1 k g i n p e r i o d I I . The o v e r a l l mean r e s u l t e d i n 2.6 k g FCM p e r k g o f f o r a g e d r y m a t t e r . The a v e r a g e w e e k l y m i l k y i e l d o f a l l cows d e c l i n e d l i n e a r l y . '.The ANOVA o f t h e m i l k y i e l d and t h e FCM b a s e d on the- w e e k l y a v e r a g e s o f a l l cows i n d i c a t e d a s i g n i f i c a n t d e c r e a s e d u r i n g t h e w h o l e e x p e r i m e n t . The l i n e a r r e g r e s s i o n c a l c u l a t e d on t h e w e e k l y means show t h e d e c l i n e ( F i g 9 ) . The a c t u a l m i l k y i e l d d e c l i n e d more t h a n t h e FCM. The l i n e a r r e g r e s s i o n f i t t e d t h e c u r v e s v e r y w e l l , t h e RSQ b e i n g .98 f o r b o t h e q u a t i o n s . - 47 -F i g u r e 9: D e c l i n e o f m i l k y i e l d and FCM w i t h t i m e ( l i n e a r r e g r e s s i o n s ) . M i l k , FCM (kg) o v e r 4.3.4. Rumen pH and VFA The ANOVA f o r rumen pH d i d n o t i n d i c a t e a d i f f e r e n c e b e t w e e n t h e t r e a t m e n t s ( T a b l e 14) b u t t h e p e r i o d e f f e c t s w e r e s i g n i f i c a n t . The rumen pH i n c r e a s e d f r o m 6.4 i n . p e r i o d I t o 6.8 i n p e r i o d I I due t o a c h a n g e i n t h e f o r a g e g r a i n r a t i o . T h e r e was a l s o a s i g n i f i c a n t d i f f e r e n c e b e t w e e n a n i m a l s . When t h e g r a i n i n t a k e was r e m o v e d , u s i n g i t a s a c o v a r i a t e , t h e e f f e c t s o f p e r i o d a n d a n i m a l w e r e no l o n g e r s i g n i f i c a n t . The rumen s a m p l i n g t e c h n i q u e was r e g a r d e d a s e f f i c i e n t e n o u g h t o y i e l d s a m p l e s f o r a q u a l i t a t i v e m e a s u r e m e n t o f VFA. - 48 -The means o f t h e VFA: a c e t i c , p r o p i o n i c , b u t y r i c , v a l e r i c a n d i s o v a l e r i c a c i d a r e l i s t e d i n t a b l e 14 i n m o l a r p e r c e n t a g e s . The a n a l y s i s o f v a r i a n c e p e r f o r m e d on t h e a c e t a t e / p r o p i o n a t e r a t i o r e v e a l e d no s i g n i f i c a n t e f f e c t on t r e a t m e n t o r a n i m a l . The s i g n i f i c a n t e f f e c t o f p e r i o d - was c a u s e d by t h e i n c r e a s e d g r a i n i n t a k e d u r i n g p e r i o d I w h i c h c o u l d be shown b y u s i n g t h e g r a i n i n t a k e as a c o v a r i a t e . T a b l e 14: Rumen pH and p r o p o r t i o n o f r u m i n a l v o l a t i l e f a t t y a c i d s i n m o l a r p e r c e n t s . Rumen ( m o l a r %) Ace.t/ pH A c e t P r o p B u t V a l I s o v a l P r o p >. N u t r o L a c 6.64 53.89 24.82 16.13 2.56A 2.60 2.36 C o n t r o l 6.64 52.23 24.83 14.74 2.48 2.72 2.41 I n t h e f e e d i n g t r i a l m ost v a r i a b l e s r e v e a l e d a s i g n i f i c a n t d i f f e r e n c e b e t w e e n t h e a n i m a l s . The v a r i a b l e s body: 1 w e i g h t c h a n g e ; c t o t a l i n t a k e as a p e r c e n t o f body w e i g h t a n d a c e t a t e / p r o p i o n a t e r a t i o w e r e n o t s t a t i s t i c a l l y s i g n i f i c a n t . The a n a l y s i s o f c o v a r i a n c e w i t h body w e i g h t c h a n g e as a c o v a r i a t e d i d n o t c a u s e any e f f e c t s t o be s i g n i f i c a n t t h a t w e r e n o t a l r e a d y s i g n i f i c a n t i n t h e ANOVA.1 • • F e e d i n t a k e , m i l k y i e l d a n d body w e i g h t c h a n g e as an a v e r a g e p e r cow and p e r i o d a r e l i s t e d i n t h e a p p e n d i x t a b l e 1. - 49 -4.4. D i g e s t i b i l i t y T r i a l One a n i m a l o f t h e c o n t r o l g r o u p f e l l s i c k d u r i n g t h e f i r s t d i g e s t i b i l i t y t r i a l . The o b s e r v a t i o n s r e c o r d e d f o r t h a t a n i m a l i n t h e f i r s t D - t r i a l w e r e n o t i n c l u d e d i n t h e ANOVA. 4.4.1. I n t a k e and m i l k y i e l d The d r y m a t t e r i n t a k e and m i l k p r o d u c t i o n w e r e s i m i l a r f o r t h e cows o n b o t h t r e a t m e n t s ( T a b l e 15). The cows f e d t h e N u t r o L a c s i l a g e consumed 17.1 k g t o t a l DM and p r o d u c e d 2 4.5 k g o f m i l k w h e r e a s t h e c o n t r o l g r o u p consumed 17.2 k g DM and y i e l d e d 22.9 k g . The f a t c o n t e n t f o r g r o u p I and I I was 3.43%:arid 3.42%. None o f t h e d i f f e r e n c e s b e t w e e n t r e a t m e n t s was s i g n i -f i c a n t . W h i l e g r a i n i n t a k e and m i l k p r o d u c t i o n w e r e s i g n i f i c a n t l y l o w e r d u r i n g t h e s e c o n d D - t r i a l t h e r e was no s i g n i f i c a n t c h a n g e i n m i l k c o m p o s i t i o n a n d f o r a g e i n t a k e . T a b l e 15: I n t a k e a n d m i l k p r o d u c t i o n d u r i n g d i g e s t i b i l i t y t r i a l s . D a i l y i n t a k e (kg) Forage G r a i n T o t a l M i l k F a t % P r o t % FCM NutroLac 9.88 7.17 17.05 24 .47 3.43 2. 91 22. 00 C o n t r o l 10.63 6.53 17 .17 22 .88 3 . 42 2 .86 20. 79 SE mean 1.43 1.93 1.27 4.72 .20 .08 3.65 F-value 1.93 .39 1.66 .79 . 85 . 49 . 39 No s i g n i f i c a n t d i f f e r e n c e between treatments a t P<.05. - 50 -4.4.2. Feces and u r i n e Amount and composition of f e c e s were very s i m i l a r f o r the two treatments. On the average 37.0 kg of feces and 20.0 kg of u r i n e (Table 17) were c o l l e c t e d per day, with dry matter contents f o r feces and u r i n e being 14.0% and 5.8%. On a moisture f r e e b a s i s feces c o n t a i n e d 12.7% crude p r o t e i n , 17.9% ash, 39.7% ADF, 65.9% NDF and 8.9% l i g n i n . U r i n e c o n t a i n e d 1.0% n i t r o g e n on a wet b a s i s (Table 17). The amount of u r i n e d i f f e r e d s i g n i f i c a n t l y between animals which may have been caused by a d i f f e r e n c e i n water consumption. A l l other o b s e r v a t i o n s r e l a t e d to f e c e s and u r i n e were not s i g n i f i c a n t l y d i f f e r e n t between animals. An e f f e c t of the p e r i o d could" be observed at P .05 f o r p r o t e i n content and l o s s i n feces and N l o s s i n u r i n e which decreased i n the second p e r i o d due to a lower p r o t e i n s u r p l u s i n the d a i l y r a t i o n . In c o n t r a s t , content of ADF; NDF and l i g n i n i n c r e a s e d s i g n i f i c a n t l y i n p e r i o d I I . Table 16: Amount (kg) and composition of feces (%). Feces DM% CP% Ash% ADF% NDF% ADL% NutroLac 36.91 14.28 12.87 18.40 39 .03 64 .95 8 .30 C o n t r o l 37.00 13. 67 12 . 58 17.23 40.59 67.03 9. 10 SE mean 3.44 .75 1.08 .86 2.92 2.29 . 88 F-value .39 1.83 .32 2.90 .27 7.91 2 .10 No s i g n i f i c a n t d i f f e r e n c e between treatments a t P<$.05. - 51 -T a b l e 17: D r y m a t t e r a n d p r o t e i n l o s s (kg) i n f e c e s and amount (kg) and c o m p o s i t i o n (%) o f u r i n e . F e c e s (kg) U r i n e DM CP k g DM% N% N l o s s N u t r o L a c 5.26 : 68 21.58 5.74 . 99 .21 C o n t r o l 5.01 . 63 18 . 11 4.86 1.10 .20 SE mean . 34 . 08 "2 .'32 .62 .10 . 02 F - v a l u e .08 .05 2. 50 . 05 1.75 . 02 i s i g n i f i c a n t d i f f e r e n c e b e t w e e n t r e a t m e n t s a t . 05 . 4.4.3. A p p a r e n t d i g e s t i b i l i t y v a l u e s The a p p a r e n t d i g e s t i b i l i t y r e s u l t s a r e shown i n t a b l e 18. A t P<$.05 t o t a l d r y m a t t e r a n d f o r a g e d r y m a t t e r d i g e s t i b i l i t y was . d i f f e r e n t , n a m e l y 69.1 and 6 5 . 0 % f o r t h e t r e a t e d and 70.7 and 6 8 . 5 % f o r t h e u n t r e a t e d s i l a g e . The o r g a n i c m a t t e r , p r o t e i n , ADF a n d l i g n i n d i g e s t i b i l i t i e s w e r e 7 3 . 2 , 7 5 . 5 , 58.3 and 37.6% as a n a v e r a g e o f b o t h t r e a t m e n t s . T o t a l DM and l i g n i n d i g e s t s i b i l i t i e s d e c r e a s e d s i g n i f i c a n t l y i n t h e s e c o n d p e r i o d . Among a n i m a l s DM and CP d i g e s t i b i l i t y o f t h e t o t a l r a t i o n was d i f f e r e n t ( P ^ . 0 5 ) , w i t h t h e h i g h e r p r o d u c i n g a n i m a l s h a v i n g h i g h e r d i g e s t i b i l i t i e s . T o t a l DM, p r o t e i n a n d o r g a n i c m a t t e r d i g e s t -i b i l i t y was p o s i t i v e l y c o r r e l a t e d w i t h g r a i n i n t a k e and m i l k p r o d u c t i o n ( r > . 7 0 ) . - 52 -Table 18: E f f e c t of treatment on apparent d i g e s t i b i l i t y v a l u e s DM For.DM OM CP For.CP ADF ADL NutroLac 69.1 65.0 72.8 75.4 76.8 58.0 36.4 C o n t r o l 70.7 68.5 73.8 75.5 76.5 58.7 38.9 SE mean 1.03 1.03 .93 1.25 3.16 3.40 7.96 F-value 31.40 15.50 6.77 .18 .25 .00 .44 Sign. * * ns ns ns ns ns * s i g n i f i c a n t at P^.05 ns not s i g n i f i c a n t - 53 -4.5. Comparison between n u t r i e n t i n t a k e and requirement The low p r o t e i n and l a c t o s e content of the m i l k as w e l l as the body weight change i n d i c a t e d an energy d e f i c i t i n the d a i l y r a t i o n . For t h i s reason the composition of the average d a i l y feed was c a l c u l a t e d (Table 19). The recommended r e -quirement of 150 g CP and 13.1 MJ DE per kg DM i n t a k e (NAS-NRC, 197 8) i s lower than the a c t u a l content of the cows' d i e t . The comparison of the amount o f crude p r o t e i n and d i g e s t -i b l e energy consumed and r e q u i r e d d a i l y r e v e a l e d t h a t the former was fed i n excess of 414 g and the l a t t e r i n excess of 16.5 MJ per day (Table 20). These excess n u t r i e n t s c o u l d y i e l d 5.0 and 2.9 kg of m i l k c o n t a i n i n g 3.5% f a t . To f u l f i l l the DE requirement .of the cows the s i l a g e would have had to^haveaan^ energy content of 11.0 MJ a t the g i v e n s i l a g e and g r a i n i n t a k e . The c a l c u l a t e d energy content of the s i l a g e appeared t o be over-estimated . Table 19:' Composition o f the average d a i l y feed. Components Crude p r o t e i n (%) 17.18 Ash (%) 8.75 ADF (%) 2 5.99 L i g n i n (%) 3.49 Di g . Energy (MJ/kg) 13.41 - 54 -P r o t e i n was f e d i n e x c e s s o f t h e r e q u i r e m e n t d u r i n g t h e c o u r s e o f t h e e n t i r e e x p e r i m e n t . The h i g h e s t s u r p l u s , as a w e e k l y a v e r a g e o f a l l c o w s , n a m e l y 2 9 % , was consumed i n t h e t h i r d week o f t h e f i r s t p e r i o d . A t t h i s t i m e CP c o n t e n t o f t h e f o r a g e was h i g h e s t and t h e g r a i n i n t a k e had o n l y s l i g h t l y d e c r e a s e d . I n t h e l a s t week o f t h e t r i a l p r o t e i n c o n s u m p t i o n was 9% a b o v e : t h e r e q u i r e m e n t . The o v e r s u p p l y o f p r o t e i n a v e r -a g e d o v e r t h e w h o l e ; e x p e r i m e n t was 15.4%. The p r o t e i n i n t a k e o f t h e h i g h p r o d u c i n g cows was o n l y s l i g h t l y a b o v e t h e r e q u i r e -ment. However, t h e l o w e r p r o d u c i n g cows w e r e f e d p r o t e i n i n e x c e s s o f up t o 40%. T a b l e 20: N u t r i e n t i n t a k e a n d r e q u i r e m e n t s . C r u d e P r o t e i n D i g . E n e r g y (MJ/kg) (g) NRC R e q u i r e m e n t 2697 226.1 I n t a k e 3101 242 . 6 E x c e s s 414 16.5 - 55 -5. DISCUSSION 5.1. F o r a g e c o m p o s i t i o n -and c h e m i c a l d e t e r m i n a t i o n . -: The s i l a g e s i n t h e e x p e r i m e n t d e s c r i b e d w e r e p r e p a r e d on t h e r e s e a r c h s t a t i o n u s i n g t h e s t a n d a r d s i l a g e m a k i n g t e c h -n i q u e s . No a t t e m p t was made t o m o d i f y t h e t e c h n i q u e s f o r e x p e r i m e n t a l p u r p o s e s e x c e p t t h a t a d d i t i o n a l m e a s u r e m e n t s ( i e . w e i g h i n g t h e f o r a g e , t r a m p i n g t h e s i l a g e ) w e r e c a r r i e d o u t . The d r y m a t t e r c o n t e n t o f t h e h e r b a g e a t e n s i l i n g was o n l y 19%. A d r y m a t t e r c o n t e n t o f 25% was i n i t i a l l y p l a n n e d b u t c o u l d n o t be r e a c h e d s i n c e t h e s i l o s had t o be f i l l e d by t h e e n d o f t h e week ( i e . L a b o r ) . The d r y m a t t e r c o n t e n t o f t h e h e r b a g e o b t a i n e d b y o v e n d r y i n g i s s l i g h t l y u n d e r -e s t i m a t e d due t o a l o s s o f v o l a t i l e compounds. The d i f f e r e n c e i n c o m p o s i t i o n o f t h e f o r a g e s was v e r y s m a l l , w h i c h made p o s s i b l e a v a l i d c o m p a r i s o n o f t h e s i l a g e t r e a t e d w i t h a d r i e d c u l t u r e o f l a c t i c a c i d b a c i l l i and t h e c o n t r o l . I t was u n -a v o i d a b l e t h a t two f i e l d s h a d t o be c u t t o f i l l t h e s i l o s . S i n c e t h e y o u n g g r a s s o f f i e l d 9 c o u l d be d i s t r i b u t e d on b o t h s i l o s i t d i d n o t f a v o r e i t h e r o f t h e s i l a g e s . I t was e v i d e n t t h a t t h e cows p r e f e r r e d t h e s i l a g e made o f t h e y o u n g g r a s s . When t h e l a y e r o f m a t u r e g r a s s s i l a g e was r e a c h e d i n t a k e d r o p p e d . The amount o f s i l a g e f o r k e d o u t o f t h e s i l o s w e i g h e d 31,400 a n d 30,800 k g f o r c o n t r o l a n d t r e a t e d s i l a g e w h i c h w o u l d c o r r e s p o n d t o 78.1 and 76.2% o f t h e w e t f o r a g e e n s i l e d . On - 56 -t h e d r y m a t t e r b a s i s t h e c o n t r o l f e e d y i e l d e d 5.6 p e r c e n t u n i t s more DM c o m p a r e d t o t h e t r e a t e d . The N u t r o L a c s i l a g e a p p e a r e d t o h a v e more a c t i v e f e r m e n t a t i o n r e s u l i n g i n more s o l u b l e compounds. A s m a l l e r r p a r t o f t h a t d i f f e r e n c e c a n be a t t r i b u t e d t o l o s s o f DM i n t h e e f f l u e n t a f t e r t h e c o l l e c t i o n p e r i o d and t o t h e u n d e r e s t i m a t i o n o f t h e e f f l u e n t DM c o n t e n t . B o t h s i l a g e s w e r e w e l l p r e s e r v e d and i n d i s t i n g u i s h a b l e as r e g a r d s o d o u r a n d g e n e r a l a p p e a r a n c e . T h e r e was l i t t l e l o s s o c c u r i n g f r o m m o l d and r o t i n t h e s i l o s e x c e p t a t t h e t o p . A g a s e o u s l o s s t h r o u g h t h e w a l l s c o u l d n o t be p r e v e n t e d . The c o n t e n t o f ADF, ADL and a s h i n c r e a s e d i n t h e s i l a g e c o m p a r e d t o t h e f o r a g e w h e r e a s t h e p r o t e i n c o n t e n t d r o p p e d . The i n c r e a s e i n ADF, ADL and a s h was c a u s e d by t h e d e t e r m i n a t i o n o f t h e s e c o m p o n e n t s on an u n c o r r e c t e d o v e n d r y m a t t e r b a s i s ( s e e b e l o w ) a n d by t h e l o s s o f m a i n l y s o l u b l e compounds v i a e f f l u e n t . The h i g h e r c o n t e n t o f ADF i n t h e N u t r o L a c s i l a g e i s b r o u g h t a b o u t b y t h e l o w e r d r y m a t t e r r e c o v e r y o f t h a t r s i l a g e c o m p a r e d t o t h e c o n t r o l . The l o w e r p r o t e i n c o n t e n t o f b o t h s i l a g e s c o m p a r e d t o t h e f o r a g e was c a u s e d b y t h e l o s s o f v o l a t i l e compounds d u r i n g t h e f e r m e n t a t i o n p r o c e s s and <:. d u r i n g o v e n d r y i n g o f t h e s i l a g e s a m p l e s t o be a n a l y z e d a s w e l l as by p r o t e i n l o s s t h r o u g h e f f l u e n t . The pH v a l u e s f o r b o t h s i l a g e s w e r e f o u n d t o be h i g h e r t h a n e x p e c t e d . The N u t r o L a c s i l a g e was e x p e c t e d t o h a v e a r e l a t i v e l y h i g h c o n t e n t o f l a c t i c a c i d w h i c h w o u l d r e s u l t i n a l o w pH s i l a g e . A h i g h pH i n d i c a t e s e i t h e r a b a d l y - p r e s e r v e d - 57 -s i l a g e which has undergone a c l o s t r i d i a l f e r m e n t a t i o n or a w e l l - p r e s e r v e d s i l a g e i n which l i t t l e f e r m e n t a t i o n has taken p l a c e ( W i l k i n s , 1974). However, i.high moisture s i l a g e s have a hi g h e r b u f f e r i n g c a p a c i t y . T h e r e i s an i n v e r s e r e l a t i o n s h i p between s i l a g e dry matter and pH value (Larsen and Jones, 1973). Jones)(1970b) found t h a t the b u f f e r i n g c a p a c i t y , the. a b i l i t y to r e s i s t a pH change,'ywas higher i n c o c k s f o o t than i n r y e g r a s s . He a l s o found t h a t l i b e r a l N f e r t i l i z a t i o n l e d to an i n c r e a s e d s i l a g e pH. The i n c r e a s e i n pH wit h time r e f e r s to a t y p i c a l change i n pH du r i n g the fer m e n t a t i o n of a low sugar crop a c c o r d i n g to W i l k i n s (1974) and McDonald e t a l . (1964). The high pH of the s i l a g e s i s i n agreement wi t h the i n c r e a s e i n the e f f l u e n t pH over time. Forage crops such as d a c t y l i s glomerata are f r e q u e n t l y low i n s o l u b l e carbohydrates (Jones, 1970a,1970b; Jones et a l . , 1961; McDonald and Wittenbury, 1973; Waite and Boyd, 1953) The l a c t i c a c i d i s formed by the fer m e n t a t i o n of carbohydrates, the amount of which w i l l d e c i d e the r a p i d i t y of the a c i d s being formed. The t i t r a t a b l e a c i d i t y determined on the d i s t i l l a t e o f the toluene d i s t i l l a t i o n was more marked i n the c o n t r o l s i l a g e than i n the NutroLac s i l a g e , which i n d i c a t e d t h a t the c o n t r o l s i l a g e c o n t a i n e d more v o l a t i l e f a t t y a c i d s . L a c t i c a c i d i s known to have a low v o l a t i l i t y . McDonald and Dewar (1960) found a mean v o l a t i l i t y of 8.7% f o r l a c t i c a c i d compared to a v o l a t i l i t y o f 87.9% f o r a c e t i c a c i d i n 28 s i l a g e s . The - 58 -N u t r o L a c s i l a g e may h a v e c o n t a i n e d somewhat more l a c t i c a c i d i n d i c a t e d b y a l o w e r pH, s i n c e l a c t i c a c i d h a s a much h i g h e r d i s s o c i a t i o n c o n s t a n t t h a n a c e t i c o r b u t y r i c a c i d . The u s e o f o v e n d r y i n g i n t h e d e t e r m i n a t i o n o f t h e DM c o n t e n t o r c h e m i c a l c o m p o s i t i o n o f f e r m e n t e d f e e d s h a s p r o v e n u n s a t i s f a c t o r y . V o l a t i l e compounds w h i c h f u r n i s h e n e r g y t o t h e a n i m a l a r e l o s t i n t h e o v e n d r y i n g p r o c e s s . Schmld-. e t ' a l . (19 70) c o n c l u d e d t h a t b i o c h e m i c a l d e t e r m i n a t i o n s s h o u l d be c o n d u c t e d on f r e e z e - d r i e d m a t e r i a l . L a r s e n and J o n e s (1973) s u g g e s t e d t h a t e i t h e r f r e e z e d r y i n g o r o v e n d r y i n g w o u l d r e s u l t i n t h e l e a s t damage t o t h e s i l a g e s b e i n g a n a l y z e d . L a r s e n and J o n e s (1973) f o u n d t h a t a d r y m a t t e r l o s s o f up t o 12.8% r e s u l t e d f r o m o v e n d r y i n g . H a i g h and H o p k i n s (19 77) f o u n d v a l u e s up t o 1 1 % and W i l s o n e t a l . (1964) up t o 2 2 . 1 % . J o n e s and L a r s e n (1974) showed a 7.4% h i g h e r DM i n t a k e u s i n g t o l u e n e d i s t i l l a t i o n f o r DM d e t e r m i n a t i o n . T h e r e i s g e n e r a l a g r e e m e n t t h a t t h e g r e a t e s t d i f f e r e n c e b e t w e e n d r y m a t t e r e s t i m a t e d by o v e n d r y i n g and t o l u e n e d i s t i l -l a t i o n o c c u r s i n s i l a g e s o f h i g h pH and l o w DM c o n t e n t . U n d e r t h e s e c o n d i t i o n s t h e c o n c e n t r a t i o n o f t o t a l v o l a t i l e f a t t y a c i d s was h i g h and t h e s e a c i d s w e r e r e a d i l y l o s t b y o v e n d r y i n g ( W i l s o n e t a l . , 1 9 6 4 ) . The 17% h i g h e r v a l u e f o r t o l u e n e d r y * m a t t e r e x p r e s s e d as p e r c e n t a g e o f t h e o v e n DM i s i n t h e r a n g e f o u n d by o t h e r w o r k e r s . A p o s s i b l e e r r o r f o r t h e h i g h e r t o l u e n e d r y m a t t e r c o u l d be t h e i n c o m p l e t e r e c o v e r y o f w a t e r d u r i n g t h e d i s t i l l a t i o n - 59 -process but i s not very l i k e l y . The d i s t i l l a t i o n of a 50 g sample lasted 60-90 minutes, which may be r e l a t i v e l y short, but heating was not discontinued u n t i l two equal readings at 15 minute in t e r v a l s had been obtained. The toluene d i s t i l e l a t i o n required 5 -to 8 hours according to the procedure by Dewar and McDonald (1961) and Wilson et a l . (1964). However results of Brahmakshatriya and' Donker '•(19 71) iridicated. that 1.5 hour of d i s t i l l a t i o n was s u f f i c i e n t . To ensure complete recovery of moisture Larsen and Jones (1973) d i s t i l l e d samples for 2 hours. The shorter d i s t i l l a t i o n time appears to be s u f f i c i e n t and i s feasible i f the sample i s ground f i n e l y , decreased i n size (50 g versus 65 g), boiled . rapidly and d i s t i l l a t i o n flasks with wider necks are used. The underestimation of the oven DM resulted i n an exag-geration of the increase in f i b e r and ash content of herbage upon e n s i l i n g . S i m i l a r l y the recovery of ash, ADF and l i g n i n were overestimated, which led to recoveries of over 10 0% of what was ensiled. The opposite i s v a l i d for protein since some of the protein may have been l o s t i n drying. In order to obtain- the true silage composition, the c chemical determinations should be ca r r i e d out on a fresh or thawed silage sample. Fresh samples are much more d i f f i c u l t to handle compared to dried ones. If the weighing papers can be digested (ie. Kjeldahl) frozen samples can be used without major d i f f i c u l t y . The expression of the oven dried sample on a toluene DM basis would lead to an error i n either d i r e c t i o n - 60 -d e p e n d i n g on t h a t p a r t i c u l a r f r a c t i o n i f i t was i n c r e a s e d o r d e c r e a s e d d u r i n g t h e d r y i n g p r o c e s s . V a l i d d i g e s t i b i l i t y v a l u e s c a n o n l y be o b t a i n e d i f b o t h s i l a g e and f e c e s a r e d e t e r -m i n e d i n t h e same way. L e v y (1956) f o u n d t h a t t h e t o l u e n e d i s t i l l a t i o n o f 26 f e c a l s a m p l e s o f s t e e r s g a v e 12.7% h i g h e r DM v a l u e s c o m p a r e d t o o v e n d r y i n g a t 80°C. I f t h i s f i g u r e c a n be t a k e n a s a v a l i d a v e r a g e , i t i s s u g g e s t e d t h a t DM o f f e c e s s h o u l d be o b t a i n e d by t o l u e n e d i s t i l l a t i o n . - 61 -5.2. S i l a g e e f f l u e n t and temperature C a s t l e and Watson (1973) c a l c u l a t e d t h a t there should be n e g l i g i b l e amounts o f s i l a g e e f f l u e n t i f herbage with a minimum dry matter content of 24-25% i s e n s i l e d . T h i s study was based on 38 s i l a g e s , 16 e n s i l e d i n vacuum s i l o s of a c a p a c i t y of 2 3 to 45 tonnes and 22 e n s i l e d i n s m a l l PVC s i l o s of a one tonne c a p a c i t y . Other workers found t h a t seepage l o s s i s p r a c t i c a l l y e l i m i n a t e d when the moisture content i s reduced to about 68-70% (Murdock e t a l . , 1958; Gordon e t a l . , 1959). Gordon e t a l . (1957) r e p o r t e d dry matter l o s s e s as e f f l u e n t o f 12 and 13% from an 82% moisture g r a s s - c l o v e r crop s t o r e d i n s i l o s o f 8 m h e i g h t . The t o t a l dry matter l o s t as seepage (1.5 and 2.5%) was lower compared t o experiments of pr e v i o u s years u s i n g the same f a c i l i t i e s ( F i s h e r e t a l . , 1978) as the prese n t experiment. The dry matter content of the f l u i d l o s s was a l s o lower than i n o ther years when forage of a h i g h e r dry matter content was e n s i l e d . Purves and McDonald (196 3) found a s i m i l a r dry matter content o f 4.29% i n the r u n - o f f of a forage e n s i l e d at 14.2% dry matter. The r e s u l t s o b t a i n e d by F i s h e r e t a l . (1978) and Purves and McDonald (1963) suggest t h a t the dry matter content of e f f l u e n t i s u s u a l l y not below 4% and i n c r e a s e s w i t h a h i g h e r dry matter content of the herbage. There i s no s t r i c t r e l a t i o n between t o t a l dry matter l o s s and dry matter content of the forage as i s e v i d e n t from t h i s experiment. The e f f l u e n t l o s s e s from the s i l a g e c o n t a i n i n g the a d d i t i v e were almost double t h e l o s s e s f r o m t h e c o n t r o l s i l a g e a l t h o u g h f o r a g e o f t h e same d r y m a t t e r h a d b e e n e n s i l e d . The d e c r e a s e i n e f f l u e n t f l o w was a c c o m p a n i e d w i t h an i n c r e a s e i n t h e n u t r i e n t c o n t e n t o f t h e e f f l u e n t . F i s h e r e t a l . (1978) f o u n d an a v e r a g e p r o t e i n c o n t e n t o f 16.4% f o r t h e f i r s t d a y c o m p a r e d t o 26.1% a f t e r 25 d a y s . I n t h e p r e s e n t s t u d y t h e p r o t e i n c o n t e n t i n c r e a s e d o v e r t h e same t i m e . f r o m 19.2 t o 3 3.2% f o r b o t h s i l a g e s . The a s h c o n t e n t i n c r e a s e d s i g n i f i c a n t l y w i t h t i m e b u t n o t t o t h e same e x t e n t as p r o t e i n . S k i n n e r (1978) f o u n d i n a s i m i l a r e x p e r i m e n t a n o n - s i g n i f i c a n t i n c r e a s e i n t h e a s h c o n t e n t . The c o n t e n t o f WSC was n o t d e t e r m i n e d i n t h e p r e s e n t e x p e r i m e n t . F i s h e r e t a l . (1978) f o u n d a n l a v e r a g e WSC c o n t e n t o f 19.6 g/1. I n c o n t r a s t t o p r o t e i n c o n t e n t t h e c o n t e n t o f WSC d e c r e a s e d s i g n i f i c a n t l y w i t h t i m e r e f l e c t i n g t h e e x t e n t o f f e r m e n t a t i o n . The d e g r e e o f c e l l b r e a k d o w n i s r e p r e s e n t e d by t h e p r o t e i n c o n t e n t a n d l o s s . The e f f l u e n t o f t h e s i l a g e c o n t a i n i n g t h e a d d i t i v e d i d n o t ha v e a s i g n i f i c a n t l y h i g h e r p r o t e i n c o n t e n t b u t s i n c e t o t a l f l u i d l o s s was a l m o s t d o u b l e p r o t e i n l o s s was s i g n i f i c a n t l y i n c r e a s e d . T h i s was c o n s i d e r e d t o be due t o a s t i m u l a t e d r a t e o f f e r m e n t a t i o n . The l o w e r c o n t e n t o f a s h f o u n d i n t h e e f f l u e n t o f t h e t r e a t e d s i l a g e , r e p r e s e n t i n g e x t r a c e l l u l a r m a t e r i a l , was due t o more s e e p a g e . The pH o f t h e r u n - o f f was l o w e r c o m p a r e d t o r e s u l t s f o u n d by E t t a l a e t a l . (1975) b a s e d on 12 s i l a g e s . T he l o w e r - e f -f l u e n t pH o f t h e N u t r o L a c t r e a t e d s i l a g e was e x p e c t e d due t o s t i m u l a t e d f e r m e n t a t i o n . The i n c r e a s e i n e f f l u e n t pH w i t h - 63 -time i n d i c a t e d t h a t a low sugar crop had been e n s i l e d ( W i l k i n s , 1974) . The temperature i n the s i l o s i s r e l a t e d t o the moisture content i n the sense t h a t a low moisture s i l a g e u s u a l l y has a h i g h e r temperature. The high e r temperature i s not caused d i r e c t l y by the low moisture but w i l t i n g of herbage b e f o r e e n s i l i n g r e s u l t e d i n s i l a g e of lower d e n s i t y . Lowr:density, i n t u r n , i s conducive to a i r i n f i l t r a t i o n , which promotes o o x i d a t i o n and d e t e r i o r a t i o n of s i l a g e . Skinner (1978) found, u s i n g the same s i l o s as the present experiment, peak tempera-t u r e s o f 31.4 and 33.6°C f o r herbage e n s i l e d at 22.4 and 25.0% DM. The maximum temperatures of 2 9.1 and 30.3 UC f o r c o n t r o l and NutroLac s i l a g e having a dry matter content of 19.1 and 18.9%, r e s p e c t i v e l y , are comparable to those found by Skinner. Higher temperatures are r e p o r t e d by C a s t l e and Watson (1970) i n some experiments and lower i n others (C a s t l e e t r l a l . , 1977). The temperature rose i n about 10 days t o i t s maximum and then began to l e v e l o f f due to the d e p l e t i o n o f oxygen. The always s l i g h t l y h i g h e r temperature i n the NutroLac S i l a - A i d s i l a g e was c o n s i d e r e d to be due to an i n c r e a s e d f e r m e n t a t i o n . There was a d i f f e r e n c e of almost 6 degrees T-between the upper and lower thermocouples a t the peak temper-a t u r e . T h i s d i f f e r e n c e was a t t r i b u t e d to the d e n s i t y and dry matter of the forage e n s i l e d a t t h a t p a r t i c u l a r l e v e l i n the s i l o . The lower thermocouples were i n s e r t e d i n the morning when herbage of 19-20% DM was e n s i l e d , w h ile the upper thermocouples were put i n l a t e r on t h a t day a f t e r e n s i l i n g g rass of 23-24% dry matter. The d e n s i t y of the forage near the lower thermocouple was c o n s i d e r e d to be higher due t o a lower dry matter content and a g r e a t e r compaction from the m a t e r i a l packed i n on top of t h a t l a y e r . A good i n d i c a t o r of the k i n d of f e r m e n t a t i o n t a k i n g p l a c e would be the measurement of the r a t e of drop i n the s i l a g e pH. Due to the absence of pH e l e c t r o d e s the pH c o u l d not be measured. Sampling of the forage would have n e c e s s i t a t e d opening of the s i l o s which wouldn't have favoured anaerobic c o n d i t i o n s . Sprague and T a y l o r (19 77) u s i n g pH e l e c t r o d e s found t h a t medium f e r t i l i z e d o r chardgrass harvested at a l a t e stage of m a t u r i t y a t t a i n e d a pH o f 4.2 w i t h i n 15 hours, whereas th a t cut at e a r l y m a t u r i t y r e q u i r e d 48 hours. A p p l y i n g of N f e r t i l i z e r a t h i g h r a t e s impaired drop i n pH f o r a longer time due to a higher b u f f e r i n g c a p a c i t y of the s i l a g e . S a t i s -f a c t o r y r e s u l t s of pH e l e c t r o d e s c o u l d be o b t a i n e d up to a forage dry matter content of•30%.-M i l l e r and C l i f t o n (1965) i n d i c a t e d t h a t feed a d d i t i v e s are not very p r a c t i c a l to reduce n u t r i e n t l o s s e s v i a seepage when low dry matter forage i s e n s i l e d . T h i s was proven t o be t r u e i n the present study. The s i l a g e c o n t a i n i n g the a d d i -t i v e had a s t i m u l a t e d f e r m e n t a t i o n but a l s o double the n u t r i e n t l o s s . Waldo (19 77) recommended a forage dry matter content of 35-45% f o r v e r t i c a l s i l o s , which would e l i m i n a t e seepage l o s s and the r e s u l t a n t s i l a g e s t i l l meet n u t r i t i o n a l c r i t e r i a . - 65 -5.3. Feeding and d i g e s t i b i l i t y t r i a l Chemical composition and fermentation c h a r a c t e r i s t i c s can i n f l u e n c e the v o l u n t a r y i n t a k e of s i l a g e . Since there were no major d i f f e r e n c e s i n composition between the two s i l a g e s a n o n - s i g n i f i c a n t d i f f e r e n c e i n i n t a k e was expected and i n f a c t was the case. C a s t l e and Watson (1970) found s i g n i f i c a n t l y h i g h e r DM i n t a k e s when grass of s i m i l a r com-p o s i t i o n and DM content was t r e a t e d with formic a c i d before e n s i l i n g . S i m i l a r r e s u l t s were obtained by other workers (Barry, 1976; Lan c a s t e r e t a l . , 1977). The drop i n t o t a l DM consumption over time was brought about by the r e d u c t i o n i n g r a i n allowance. The hot summer weather d i d not favour forage i n t a k e i n the f i r s t p e r i o d . I t i s suggested t h a t experiments on forage i n t a k e should not be c a r r i e d out i n summer. Furthermore, the g r a i n allowance should be kept lowere.than i n the present t r i a l to remove a s u b s t a n t i a l d e p r e s s i o n on forage i n t a k e . The g r a i n a l l o t t m e n t c o u l d be kept lower and would s t i l l meet the requirements i f i t was high e r i n energy and lower i n p r o t e i n content. A h i g h e r DM content i n the s i l a g e has been found by d i f f e r e n t workers to i n c r e a s e i n t a k e (Murdoch, I960', W i l k i n s et a l . , 1971> Gordon and Murdoch, 197 8). The body weight l o s s i n the second p e r i o d i s a t t r i b u t e d to the lower g r a i n i n t a k e and may i n d i c a t e a low energ y content of the forage. The d i f f e r e n c e i n body weight change of 4.6 kg per p e r i o d i n favour of the NutroLac s i l a g e i s balanced w i t h - 66 -a s l i g h t l y h i g h e r m i l k p r o d u c t i o n o f t h e cows on c o n t r o l . s i l a g e . F i s h e r (1977) and S k i n n e r (1978) f o u n d w e i g h t g a i n s o f 25.2 and 23.8 k g p e r 5-week p e r i o d , r e s p e c t i v e l y . The f o r m e r was a c o r n - a l f a l f a c u b e s i l a g e t r i a l , w h e r e a s t h e l a t t e r was a l s o an o r c h a r d g r a s s t r i a l b u t g r a i n was f e d a t an e v e n h i g h e r r a t e t h a n i n t h e p r e s e n t e x p e r i m e n t . The r e g r e s s i o n e q u a t i o n w h i c h was b a s e d on t h e ADF c o n t e n t , u s e d t o c a l c u l a t e t h e DE c o n t e n t o f t h e s i l a g e , seemed t o o v e r -e s t i m a t e t h e e n e r g y c o n t e n t o f o r c h a r d g r a s s . The e n e r g y v a l u e o f a f e e d c a n n o t o n l y be a s s e s s e d by i t s ADF c o n t e n t . T h e r e i s g e n e r a l a g r e e m e n t t h a t a h i g h c o n c e n t r a t e r a t i o n b r i n g s a b o u t a s h i f t i n t h e m o l a r p r o p o r t i o n s o f t h e r u m i n a l VFA, n a m e l y a d e c r e a s e i n t h e p r o p o r t i o n o f a c e t a t e , w h i c h i s a known p r e c u r s o r o f t h e s h o r t c h a i n f a t t y a c i d s i n b u t t e r -f a t , a n d an i n c r e a s e i n p r o p i o n a t e . The s h i f t i n m o l a r p r o -p o r t i o n s c a u s e d t h e l o w e r pH o f t h e r u m i n a l f l u i d i n p e r i o d I when t h e g r a i n i n t a k e a c c o u n t e d f o r 49.7% o f t h e t o t a l DM i n t a k e . Rumen pH i s f o u n d t o be l o w e r f r o m cows f e d f e r m e n t e d f o r a g e s c o m p a r e d t o hay ( S c h i n g o e t h e e t a l . , 1976). A h i g h e r t o t a l VFA c o n c e n t r a t i o n f o r cows on s i l a g e i s a t t r i b u t e d t o d i f f e r e n c e s i n VFA i n g e s t i o n r a t h e r t h a n VFA p r o d u c t i o n w i t h i n t h e rumen ( R o f f l e r e t a l . , 1967). I n t h e p r e s e n t e x p e r i m e n t no s i g n i f i c a n t e f f e c t o f t r e a t -ment o n m i l k p r o d u c t i o n was f o u n d . The a v e r a g e m i l k y i e l d was c o m p a r a b l e t o t h r e e p r e v i o u s e x p e r i m e n t s when cows o f t h e same h e r d w e r e u s e d ( F i s h e r , 1977, 1978 • , - S k i n n e r , 1978). - 67 -Bolsen (1978), summarizing data of 17 s i l a g e s , where ai d s to fermentation (mainly l a c t o b a c i l l u s i n o c u l a ) were a p p l i e d , s t a t e d t h a t milk p r o d u c t i o n was i n s i g n i f i c a n t l y i n c r e a s e d by the use of a d d i t i v e s . C a s t l e and Watson (1970) r e p o r t e d a s i g n i f i c a n t i n c r e a s e i n milk p r o d u c t i o n when s i l a g e t h a t was t r e a t e d with formic a c i d was f e d . The data summarized by Waldo (1978) i n d i c a t e d t h a t m i l k p r o d u c t i o n was i n c r e a s e d by 5 and 13% f o r formic a c i d and formaldehyde 1 treatment, r e s p e c t i v e l y , r e l a t i v e to c o n t r o l . The milk s o l i d s p r o t e i n (3.04%) and l a c t o s e (5.10%) were 6.3 and 5.8% higher i n the experiments by F i s h e r (1977, 1978) and Skinner (1978). The reduced content of these two milk c o n s t i t u e n t s i n d i c a t e d a shortage i n energy. Emery (1978) rev i e w i n g l i t e r a t u r e to assess the i n f l u e n c e of d i e t a r y energy on the c o n c e n t r a t i o n of p r o t e i n i n milk found a s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n (P<.01) between d i e t a r y energy i n t a k e and content of milk p r o t e i n . In h i s study the percentage of m i l k p r o t e i n i n c r e a s e d .063 u n i t s per MJ of i n c r e a s e d d a i l y net energy i n t a k e . The s o l i d s - c o r r e c t e d m i l k was c a l c u l a t e d f o r comparison w i t h f a t - c o r r e c t e d m i l k . Both FCM and SCM p r e d i c t the amount of milk with an energy content of 3.14 MJ GE per kg. T y r r e l l and Reid (1965) demonstrated t h a t the energy v a l u e of l o w - f a t m i l k i s underestimated by the FCM equation. The equation f o r SCM p r e d i c t e d the milk energy output o f cows producing low f a t milk e f f e c t e d by d i e t a r y changes as a c c u r a t e l y as t h a t of normal m i l k . In the present study the amount of FCM and i t s energy value - 68 -was overestimated i n both p e r i o d s . The o v e r e s t i m a t i o n was s m a l l e r i n p e r i o d I than II (.3% vs 1.8%). The h i g h e r amount of FCM than SCM was brought about by the r e l a t i v e l y low p r o t e i n and l a c t o s e content of the milk. In periods I, the amount of SCM was h i g h e r f o r e i g h t of twelve animals. The m i l k of these e i g h t animals had a f a t content of l e s s than 2.8% or a s o l i d s - n o n - f a t content of over 8.6%. The p r o t e i n and l a c t o s e content were '•'<•.. lowest f o r the two 2 8-month o l d animals, which r e s u l t e d i n an o v e r e s t i m a t i o n of FCM by 3.7% compared to SCM. The SCM equation appears to g i v e a b e t t e r estimate of the energy output i n m i l k both f o r l o w - f a t milk and milk low i n p r o t e i n and l a c t o s e . A l l the d i g e s t i b i l i t i e s were r e l a t i v e l y high f o r both treatments. The DM d i g e s t i b i l i t i e s are overestimated because fe c e s DM was determined by oven d r y i n g . Toluene d i s t i l l a t i o n i s known to g i v e higher DM v a l u e s . A 10% DM l o s s of feces d u r i n g the oven d r y i n g process would reduce the DM d i g e s t -i b i l i t y value by 3 u n i t s . The i n c r e a s e i n apparent DM and CP d i g e s t i b i l i t y of the t o t a l r a t i o n with high producing-cows i s a t t r i b u t e d to d i f f e r e n t f a c t o r s . The DM d i g e s t i b i l i t y i n c r e a s e s with higher g r a i n i n t a k e . The main"reason f o r the higher D-value f o r p r o t e i n i s due to t o t a l p r o t e i n i n t a k e which was i n excess e s p e c i a l l y f o r low producing cows. The high y i e l d e r s r e c e i v e d a l a r g e r p r o p o r t i o n of t h e i r d a i l y p r o t e i n i n t a k e from g r a i n which i s more d i g e s t i b l e than forage. The supplementation of s i l a g e with c o n c e n t r a t e a l s o leads to improved n i t r o g e n r e t e n t i o n (Thomson, 1968". G r i f f i t h s , 1969; - 69 -G r i f f i t h s a n d S p i l l a n e , 1970", G r i f f i t h s , , " S p i l l a n e a n d B a t h , 1 9 7 1 ) . A p r o b a b l e u n d e r e s t i m a t i o n o f t h e f o r a g e p r o t e i n c o n t e n t . l e d t o a s m a l l e r D - v a l u e m a i n l y f o r t h e cows h a v i n g a h i g h . f o r a g e i n t a k e . I n c o n t r a s t , t h e u n d e r e s t i m a t i o n o f t h e CP c o n t e n t o f t h e f e c e s due t o a l o s s o f v o l a t i l e compounds d u r i n g t h e o v e n d r y i n g p r o c e s s i n c r e a s e d t h e a p p a r e n t p r o t e i n d i g e s t i b i l i t y f o r a l l cows. Waldo and G o e r i n g (1976) r e p o r t e d a n o n - s i g n i f i c a n t i n c r e a s e i n DM d i g e s t i b i l i t y by a p p l y i n g a c o m m e r c i a l i n o c u l u m w h i l e t h e p r e s e n t e x p e r i m e n t i n d i c a t e d a s i g n i f i c a n t d e c r e a s e i n the. DM d i g e s t i b i l i t y . The .use- o f f o r m i c a c i d a s s i l a g e a d d i t i v e h a s b e e n shown t o i m p r o v e DM d i g e s t i b i l i t y by 1 0 % , w h e r e a s t h e u s e o f f o r m a l d e h y d e r e s u l t e d i n a 2% l o w e r DM d i g e s t i b i l i t y ( W a l d o , 1 9 7 8 ) . - 70 -6. SUMMARY AND CONCLUSION The e f f e c t i v e n e s s o f t h e s i l a g e a d d i t i v e N u t r o L a c S i l a - A i d i n p r e s e r v a t i o n o f f o r a g e n u t r i e n t s was t e s t e d on a f i e l d s c a l e . F o r t h a t r e a s o n two u n i f o r m o r c h a r d g r a s s s i l a g e s w e r e p r e p a r e d . To one s i l a g e t h e a d d i t i v e , c o n t a i n i n g a d r y c u l t u r e o f l a c t o b a c i l l i , was m i x e d a t a r a t e o f 1/2 k g p e r t o n n e f o r a g e . The amount o f e f f l u e n t m e a s u r e d and s a m p l e d d u r i n g t h e f i r s t month a f t e r e n s i l i n g r e v e a l e d a ^ s u b s t a n t i a l d i f f e r e n c e b e t w e e n t r e a t e d and u n t r e a t e d s i l a g e . The a d d i t i v e s t i m u l a t e d f e r m e n t a t i o n and c o n s e q u e n t l y f a s t e r r e l e a s e o f c e l l s a p r e -s u l t e d i n s i g n i f i c a n t l y h i g h e r e f f l u e n t l o s s e s . '"'The s e e p a g e r e d u c e s n o t o n l y t h e p r o t e i n and e n e r g y l e v e l o f t h e s i l a g e b u t a l s o t h e l e v e l o f m i n e r a l s a n d v i t a m i n s . E f f l u e n t i s v e r y u n d e s i r a b l e i n d r a i n s o r - s t r e a m s b e c a u s e i t i s a f a v o u r a b l e medium f o r t h e g r o w t h o f f u n g i ( R u r v e s and M c D o n a l d , 196 3 ) . On t h e o t h e r h a n d t h e same a u t h o r s a l s o i n d i c a t e d t h a t s i l a g e r u n - o f f may be a u s e f u l s o u r c e o f p l a n t n u t r i e n t s . W i l t i n g o f g r a s s t o a b o u t 25% p r i o r t o e n s i l i n g w o u l d r e d u c e e f f l u e n t f l o w m a r k e d l y , w h i l e f i e l d l o s s e s c o u l d be s t i l l k e p t l o w and a d e s i r a b l e c o m p a c t i o n o f t h e f o r a g e o b t a i n e d . A l t h o u g h no d a t a on t h e VFA and l a c t i c a c i d c o n t e n t was o b t a i n e d i t a p p e a r e d t h a t b o t h ; s i l a g e s w e r e w e l l p r e s e r v e d . T h e r e was o n l y minimum s p o i l a g e i n b o t h s i l o s and r e c o v e r i e s o f - d i f f e r e n t f e e d c o m p o n e n t s was h i g h . The i n c r e a s e d e f f l u e n t - 71 -l o s s f o r t r e a t e d s i l a g e l e d to lower r e c o v e r i e s f o r t h a t s i l a g e . The chemical composition of the s i l a g e s showed t h a t the t r e a t e d s i l a g e had a g r e a t e r p r o p o r t i o n of ash, ADF and NDF compared to the c o n t r o l brought about by the l o s s of more s o l u b l e compounds due to a more a c t i v e f e r m e n t a t i o n . Both s i l a g e s were fed to 12 H o l s t e i n cows i n a switchback t r i a l f o r 15 weeks. N e i t h e r i n t a k e nor m i l k p r o d u c t i o n and composition showed a s i g n i f i c a n t d i f f e r e n c e (P $.05) between the two treatments. High i n t a k e s and milk y i e l d s were achieved, the average values being 10.1 and 2 8.0 kg per day, r e s p e c t i v e l y . However, both body weight change and milk composition i n d i c a t e d a low energy content i n the d a i l y r a t i o n . Orchardgrass has o f t e n shown to be low i n WSC. The apparent DM d i g e s t i b i l i t y of the t o t a l r a t i o n was found to be s i g n i f i c a n t l y lower i n the t r e a t e d s i l a g e . D-values f o r OM, CP and AFD were s i m i l a r ' f o r both treatments. The present experiment i n d i c a t e d t h a t the use of NutroLac S i l a - A i d d i d not improve s i l a g e q u a l i t y , but r e s u l t e d i n more e f f l u e n t l o s s , lower r e c o v e r y from storage and reduced DM d i g e s t i b i l i t y . - 72 -7. BIBLIOGRAPHY Barry, T. 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Zimmer, E. 1966 . D i e N e u f a s s u n g d e s G a r f u t t e r s c h l i i s s e l s n a c h F l i e g . Das w i r t s c h . e i g e n e F u t t e r 3: 2 9 9 - 3 0 3 . Zimmer, E. 1971. F a c t o r s a f f e c t i n g s i l a g e f e r m e n t a t i o n i n t h e s i l o . I n t e r n a t i o n a l S i l a g e R e s e a r c h C o n f e r e n c e -T e c h n i c a l p a p e r s . N a t i o n a l S i l o A s s o c i a t i o n , W a t e r l o o , I A , p 58 ( C i t e d i n B o l s e n , K. K. 1 9 7 8 ) . 8. APPENDIX 1 Table 1: Feed i n t a k e , milk y i e l d and body weight change as an average per cow and p e r i o d . Pe-r i o d 7259 C o 7302 w s 7362 (Group 7514 I) 7545 7610 7239 C o 7415 w s 7453 (Group 7507 II) 7556 7611 Forage/day (kg) I 7.6 11. 4 12 . 0 7.6 9.8 9.8 6 . 4 9.4 11. 3 6.4 10. 2 11.5 Forage/day (kg) II 9.8 12 . 7 11.6 10.0 11. 4 10.5 8.6 11. 4 12.1 8.0 11. 0 12 . 6 Grain/day (kg) I 12 . 3 10.1 8.7 10.8 8.1 6 . 0 12 .1 10.5 7.9 12.9 6.0 6.4 Grain/day (kg) II 10.3 5 . 3 5.6 8.9 4.1 3.6 10. 4 8.4 4.3 10.7 3.4 .4:5 Milk/day (kg) •'. I.. • 42.7 28.3 32 . 8 36. 0 27.5 22. 7 42.2 36.5 25.2 42.5 21.8 24.7 Milk/day (kg) I I , 33.4 21.7 20 . 6 28.5 18.3 16.4 34.9 27.3 18.8 34. 3 15.2 19. 9 I n i t . Body wt.(kg) 674 590 557 560 519 533 616 590 578 626 537 546 BWC/period (kg) I -10 8 24 -11 -9 21 4 11 20 -32 -2 43 BWC/period (kg) II -11 10 -23 23 -2 3 -10 -28 -1 -40 6 -17 F i n a l Body wt.(kg) 653 608 558 572 508 557 610 573 597 554 541 572 Group I: Treatment sequence C o n t r o l - NutroLac Group I I : Treatment sequence NutroLac - C o n t r o l 

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