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- 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