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Forage and concentrate protein utilization by dairy cattle Kamande, George Matiru 1988

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FORAGE AND CONCENTRATE PROTEIN U T I L I Z A T I O N DAIRY CATTLE.  BY GEORGE MATIRU KAMANDE B.Sc.  ( A g r . ) , UNIVERSITY OF N A I R O B I , 1 9 8 3 .  A THESIS SUBMITTED I N PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE-FACULTY OF GRADUATE STUDIES  (Department of Animal Science) We a c c e p t t h i s t h e s i s a s c o n f o r m i n g t o t h e required standard.  THE UNIVERSITY OF B R I T I S H COLUMBIA A p r i l , 198 8, c j George. M a t i r u Kamande  In  presenting  degree  this  at the  thesis  in  partial  fulfilment  of  the  University of  British  Columbia,  I agree  requirements  for  of  department  this or  thesis by  for  his  publication of this thesis  or  scholarly her  may  representatives.  It  be is  granted  for extensive  by the head  understood  that  for financial gain shall not be allowed without  permission.  Department The University of British Columbia Vancouver, Canada  DE-6 (2/88)  purposes  advanced  that the Library shall make it  freely available for reference and study. I further agree that permission copying  an  of  my  copying  or  my written  ABSTRACT In the f i r s t  part of t h i s study, the r e l a t i v e i n s i t u  rumen d e g r a d a b i l i t i e s of some common Kenyan f e e d s t u f f s were e s t i m a t e d u s i n g two f i s t u l a t e d study attempted by heat  to manipulate  s t e e r s . The second rumen f e r m e n t a t i o n  p a r t of the processes  t r e a t i n g d i e t a r y p r o t e i n , and a l s o by v a r y i n g the hay  particle The  size. i n s i t u dacron  bag technique was used  to estimate  the f e e d i n g value of some common Kenyan f o r a g e s . The r a t e and extent of d r y matter  (DM) and crude p r o t e i n  in the rumen was then determined  (CP) d e g r a d a t i o n  from the incubated  samples.  E f f e c t i v e DM and CP d e g r a d a t i o n was a l s o e s t i m a t e d a t v a r i o u s rumen d i g e s t a flow  rates.  Green maize chop, fodder  sorghum, n a p i e r g r a s s ,  g r a s s , Pennisetum trachyphyllum,  rhubarb  kikuyu  l e a v e s , banana  l e a v e s , sweet potato v i n e s , desmodium and l u c e r n e had moderate to high DM and CP d e g r a d a b i l i t y  (>50%). These  f e e d s t u f f s would t h e r e f o r e o f f e r g r e a t e r p o t e n t i a l f o r conservation  f o r feeding dairy c a t t l e  i n the d r y season.  Wheat straw, maize s t o v e r , r e d oats grass and naivasha s t a r g r a s s had s i g n i f i c a n t l y  (P<0.05) lower  rumen  d e g r a d a b i l i t y . T h i s l a s t group would r e q u i r e energy  supplemental  and n i t r o g e n i n order to meet the d a i r y cow's  n u t r i e n t s requirements.  Wheat bran had a h i g h DM  d e g r a d a b i l i t y but i t s CP d e g r a d a b i l i t y was low. The digestibility  and amino a c i d a v a i l a b i l i t y of i t s p r o t e i n ii  requires  further  The  effects  of  protein  ration or  of forage  sources  together  canola with  meal  grass  1 4 . 1 9 a n d 1.71  i.e  In  situ  proteins Heat crude  treatment  showed  w i t h heat  change  intake,  both  canola  fibre  canola  (NDF)  Reduced  treatment  intake,  content  by  heat. (DM),  Milk yield  canola  was  meal.  protein  forage  resulted  milk  alfalfa  digestibility, contents  particle  yield  size  in significantly  T h e r e was no  lactose content), with  Lactose  and  (ADF)  rations.  by h e a t i n g  fibre  meal  i n v i v o d r y matter  detergent  treatment.  with heat  (except  size.  Holstein  indigestible  C P , a n d ADF d i g e s t i b i l i t y .  components,  Normal  t o t w o mean c u t l e n g t h s  b u t t e r f a tand milk  i n voluntary feed  particle  that  affected  neutral detergent  decreased  DM,  cows.  were f e d  h a y t o 24 l a c t a t i n g  f o r the complete  combination  dairy  alfalfa  h a y was c h o p p e d  (CP) and a c i d  feed  long  grass  treatment  and composition and,  using  and dehydrated  not s i g n i f i c a n t l y  lower  determined  d i d not affect  voluntary  in  yield  i n t h e s u p p l e m e n t w a s made  protein  However,  milk  l e n g t h and heat  mm.  results  digestibility also  were  orchard  Orchard  particle  on i n t a k e ,  digestibility  heated  cows.  investigations.  significant  or i t s reduced  was s i g n i f i c a n t l y  hay  higher  with  chop hay. Heat  treatment  of "alfalfa  resulted  i n lower  rations.  ADF d i g e s t i b i l i t y  and s h o r t hay p a r t i c l e  DM a n d C P d i g e s t i b i l i t y  iii  and v o l u n t a r y  of the feed  size  complete  intake  were  reduced  with  voluntary  heat  feed  t r e a t m e n t . Hay  intake  significantly.  components  increased  total  f a t increased  milk  particle  with  heat with  iv  Milk  treatment the longer  size  d i d not  yield  and i t s  of a l f a l f a . chop  affect  hay.  Only  TABLE OF CONTENTS ABSTRACT  i i  TABLE OF CONTENTS  v  LIST OF TABLES  vi  LIST OF FIGURES  viii  LIST OF APPENDIX TABLES  ix  ACKNOWLEDGEMENT  X  CHAPTER ONE: E v a l u a t i o n o f some Kenyan f o r a g e s the N y l o n bag t e c h n i q u e . Introduction L i t e r a t u r e review M a t e r i a l s and methods Results Discussion Summary and c o n c l u s i o n s  using 1 4 23 26 41 46  CHAPTER TWO: To d e t e r m i n e t h e e f f e c t o f f o r a g e p a r t i c l e l e n g t h and h e a t treatment of p r o t e i n s o u r c e s on i n t a k e , m i l k y i e l d a n d c o m p o s i t i o n and r a t i o n d i g e s t i b i l i t y i n d a i r y c a t t l e . Introduction L i t e r a t u r e review M a t e r i a l s a n d methods Results Discussion Summary and c o n c l u s i o n s G e n e r a l Summary  49 51 69 72 88 98 100  LITERATURE  103  CITED  APPENDICES  112  V  LIST OF TABLES  Page Table 1  Names and stage of h a r v e s t i n g the forage samples.25  Table 2  Chemical  Table 3  Dry matter  Table 4  Crude p r o t e i n degradation c o n s t a n t s  31  Table 5  E f f e c t i v e dry matter  32  Table 6  E f f e c t i v e crude p r o t e i n d e g r a d a b i l i t y  33  Table 7  Composition  72  Table 8  Mean extent on DM and CP degradation over the  composition  of forage samples  27  degradation c o n s t a n t s  30  degradation  of the r a t i o n  feedstuffs  experimental d u r a t i o n - i n s i t u Table 9  73  Mean extent of DM and CP degradation and a l f a l f a based  Table 10 Degradation  f o r canola  concentrates - i n s i t u  ..73  r a t e c o n s t a n t s of canola and a l f a l f a  concentrates  .78  Table 11 D i g e s t i b i l i t y and d a i l y feed i n t a k e of c a n o l a r a t i o n s over the experimental Table 12 Dry matter  and crude p r o t e i n  c o e f f i c i e n t s of canola based  based  duration digestibility rations  Table 13 D a i l y feed intake of canola treatments Table 14 Milk y i e l d and composition d u r a t i o n -canola based vi  81  81 81  over the experimental  rations  82  Table 15 E f f e c t s and  of c a n o l a  ration  treatments  on m i l k  yield  composition  Table  16 D i g e s t i b i l i t y  Table  17 D r y m a t t e r alfalfa  82  of a l f a l f a  and c r u d e  based  protein  rations  ...82  digestibility  of  treatments  Table  18 D a i l y  feed  Table  19 M i l k y i e l d  83  i n t a k e and ADF  digestibility  and c o m p o s i t i o n  for a l f a l f a  83 treatments 83  Table  20 M i l k y i e l d  and c o m p o s i t i o n  of a l f a l f a  treatments 84  vii  L I S T OF  Figure 1  FIGURES  % Degradation versus i n c u b a t i o n time -Green maize chop  Figure 2  % Degradation versus i n c u b a t i o n time  29 -Kikuyu  grass Figure 3  % Degradation versus i n c u b a t i o n time  36 -Lucerne  (LB) Figure 4  37  % Degradation versus i n c u b a t i o n time -Rhubarb leaves  Figure 5  38  % Degradation versus i n c u b a t i o n time -Canola c o n c e n t r a t e s [DM]  Figure 6  % Degradation versus i n c u b a t i o n time  74 -Canola  c o n c e n t r a t e s [CP] Figure 7  % Degradation versus i n c u b a t i o n time  75 -Alfalfa  c o n c e n t r a t e s [DM] Figure 8  % Degradation versus i n c u b a t i o n time c o n c e n t r a t e s [CP]  76 -Alfalfa 77  LIST OF APPENDIX TABLES  Appendix  1  Appendix 2  Composition  of the d a i r y  Experimental  ix  layout  rations  f o r m u l a t e d .112  i n the t r i a l  113  ACKNOWLEDGEMENTS  My s i n c e r e g r a t i t u d e goes to my r e s e a r c h J.A.  Shelford, Associate  Professor,  Animal  s u p e r v i s o r , Dr  Science  Department. "Your u n f a l t e r i n g support, guidance, encouragement and c o n s t r u c t i v e c r i t i c i s m s throughout the various  a s p e c t s of t h i s work remains c l e a r l y  1 am a l s o g r a t e f u l t o ; P r o f e s s o r Science  unmatched".  B.D. Owen, Animal  Department and Dr L . J . F i s h e r , Research  A g r i c u l t u r e Canada, A g a s s i z ,  the two other  graduate committee. T h e i r a d v i c e preparation  Scientist,  members of my  and encouragement i n the  and w r i t i n g of t h i s t h e s i s was immeasurable.  My g r a t i t u d e a l s o goes to the Kenya Government and Canadian I n t e r n a t i o n a l Development Agency (C.I.D.A.)  for  awarding the s c h o l a r s h i p that made t h i s study p o s s i b l e . S p e c i a l thanks go to the South Campus s t a f f and a l l the technicians  i n the Animal Science  laboratory  for their  assistance. Finally,  1 would l i k e to d e d i c a t e  t h i s t h e s i s to my  f a m i l y and a l l my f r i e n d s , r e a l l y wonderful p e o p l e .  CHAPTER 1 EVALUATION OF SOME KENYAN FORAGES USING THE DACRON-BAG TECHNIQUE. INTRODUCTION One o f t h e m a j o r livestock  factors  production  seasonality  limiting  potential  of f o r a g e  i n Kenya  throughout  Although  grain feeding provides  required  for exploitation  require  forages  more c o s t crops  rapid  throughout  feedstuffs  season,  season  of the g e n e t i c  after  potential  of the  are usually  t h a t growth of  the onset  fodder  of t h e r a i n s and  o r no g r o w t h a t a l l , a t t h e h e i g h t o f  falls  production  the year. rapidly  slower  The n u t r i t i v e  liveweight gains  but s t i l l  substantial  t h e end o f t h e s h o r t and e a r l y  r e q u i r e s an e v e n  as the f o r a g e  rains,  r a i n y season.  observed  i n the d r y season.  problem,  farmers  during  nutrient density  c o s t s a r e h i g h . A l s o , d a i r y cows  just  a p a t t e r n of r a p i d  after  the h i g h  season.  Intensive milk  in  i s t h e main c a u s e o f t h i s .  It is typical  o f f to l i t t l e  the d r y  to the  t o remain h e a l t h y . Fodder c r o p s  effective.  i s very  trails  feeds  the year  cow, p r o d u c t i o n  relates  p r o d u c t i o n . The uneven d i s t r i b u t i o n o f  rainfall  dairy  the e x p l o i t a t i o n of  i n the e a r l y  gains  then  o f most  matures. T h i s  until  results wet  some  Reduced m i l k  preserve  yields  are also  management  the forage  surplus  i n t h e form o f hay o r s i l a g e  . . 1  time  l o s s e s i n the dry  To overcome t h i s  have t o e i t h e r  the r a i n y season,  value  supply of  or feed  c o n c e n t r a t e s . Other p o s s i b i l i t i e s s t o c k i n g r a t e s over  the seasons may  s m a l l h o l d e r d a i r y set-up, the breeding  l i k e the adjustment of not be  in view of the imperfect  stock market. R e g u l a t i n g  forage p r o d u c t i o n  feasible  in a nature  of  the s e a s o n a l i t y of  through i r r i g a t i o n may  not be  economically  v i a b l e f o r the m a j o r i t y of s m a l l h o l d e r s because of the  high  costs involved. The  i n s i t u dacron bag  estimate al.,  technique  c o u l d be used to  the p o t e n t i a l f e e d i n g value of forages  1980). Information  (Orskov e_t  on the d e g r a d a b i l i t i e s of  f o r a g e s , of the v a r i a t i o n between s p e c i e s and  different  v a r i e t i e s , of  the d i f f e r e n c e s between p a r t s of the p l a n t and  the e f f e c t  m a t u r i t y on d e g r a d a b i l i t y , r e s u l t  understanding  in a better  of the p o t e n t i a l value of the forages and  their  d a i r y r a t i o n s . I t i s acknowledged  et a l . , 1980)  little  (Orskov  of  selection in that  i s known of the r e l a t i v e d e g r a d a b i l i t y of the wide  range of t r o p i c a l  forages and  browses a v a i l a b l e or  p o t e n t i a l l y a v a i l a b l e . A great d e a l of i n f o r m a t i o n on  forages  i s t h e r e f o r e r e q u i r e d . Accumulation of t h i s type of i n f o r m a t i o n w i l l ensure t h a t f e e d s t u f f s are a l l o c a t e d on b a s i s of t h e i r degradation outflow  r a t e s , p o t e n t i a l d e g r a d a b i l i t y and  r a t e from the rumen with a given type of  Rumen degradation  the  diet.  as measured by the nylon bag  technique  r e f e r s to the breakdown of m a t e r i a l to a s i z e small enough to leave the bag simple  and  chemical  not n e c e s s a r i l y a complete degradation  compounds. A f e e d s t u f f with low . .2  and  slow  to  degradability  could  r e s u l t i n reduced v o l u n t a r y  feed  and  thus l i m i t  and  d i r e c t relevance to the value of the feed m a t e r i a l  intake  the performance of the a n i m a l . The s i m p l i c i t y under  i n v e s t i g a t i o n make the dacron bag technique a u s e f u l t o o l i n exploring An  the feeding  attempt w i l l  value of common Kenyan  be made i n t h i s t r i a l  feedstuffs.  to e v a l u a t e and  make suggestions on the f e e d s t u f f s with a p o t e n t i a l f o r conservation  i n view of t h e i r s u p e r i o r  c h a r a c t e r i s t i c s . These feed m a t e r i a l s even out the feed  supplies  degradation w i l l presumably h e l p  a c r o s s the seasons.  Evaluation  w i l l a l s o be done and comparisons made on a l t e r n a t i v e crop residues  available. It i s anticipated  that  combinations of f e e d s t u f f s useable i n d a i r y  possible r a t i o n s w i l l be  i d e n t i f i e d . Proper s e l e c t i o n of r a t i o n i n g r e d i e n t s i s important and  in avoiding  possible depressions i n d i g e s t i b i l i t y  hence a v a i l a b l e s u p p l i e s  present  study was t h e r e f o r e  of energy and amino a c i d s . The undertaken with the f o l l o w i n g  object i v e s : a) To of b) To  determine the r a t e and extent of rumen d e g r a d a t i o n some common Kenyan  feedstuffs.  i d e n t i f y p o s s i b l e combinations of the f e e d s t u f f s to  include  i n a d a i r y cow r a t i o n .  . .3  LITERATURE REVIEW  GROWTH PATTERN OF FORAGES. Background The  Information.  s m a l l h o l d e r d a i r y p r o d u c t i o n i s mainly  the Kenyan Highlands, at an e l e v a t i o n of sea l e v e l and (Stotz,  r e c e i v e s 700  to 2,000m above  to 2,000mm of r a i n per  1983). There are about  l i v e s t o c k farms occupying  1500  located in  1.5 m i l l i o n  approximately  year  smallholder  3.5  million  hectares  (ha) of farm l a n d , the m a j o r i t y of which are l e s s than 2 ha (Odingo, farming  1971). The  importance  i s shown by the f a c t  of s m a l l h o l d e r  t h a t they r e p r e s e n t over 50% of  the n a t i o n a l l i v e s t o c k herd. In 1981, t o t a l n a t i o n a l milk and beef (Stotz,  livestock  75% and  output came from  1983). Smallholder l i v e s t o c k  65% of the smallholders  farming a l s o p r o v i d e s  g a i n f u l employment to a l a r g e number of Kenyans. Forage from s m a l l h o l d i n g s i s drawn from permanent p a s t u r e s , grass l e y s , a r a b l e fodder crops and r e s i d u e s . Under l e y s and permanent p a s t u r e s o c c u r r i n g grass s p e c i e s such as kikuyu g r a s s clandestinum),  food c r o p  naturally (Pennisetum  s t a r g r a s s (Cynodon d a c t y l o n ) , nandi  ( S e t a r i a s p h a c e l a t a ) and  rhodes grass  predominate, napier grass  (Pennisetum  sorghum (Sorghum sudanense),  setaria  ( C h l o r i s gayana) purpureum),  fodder  l u c e r n e (Medicago s a t i v a ) are  the common fodder c r o p s . Food c r o p r e s i d u e s i n c l u d e maize . .4  stover  (Zea mays), banana leaves (Musa spp.) and sweet potato  vines  (Ipomoea b a t a t a s ) among o t h e r s .  Environmental  effects  A prerequisite  on f o r a g e  quality.  f o r making more e f f i c i e n t  use of forages  i s knowing t h e i r v a l u e , as sources of p r o t e i n and energy, at their different  stages of development. T h e r e a f t e r comes the  q u e s t i o n of f e e d i n g the best a v a i l a b l e Forage q u a l i t y normally  supplements.  i n v o l v e s c o n s i d e r a t i o n s on the  p r o d u c t i v e c a p a c i t y of forages as major d i e t a r y i n g r e d i e n t s and a l s o the optimum time to harvest f o r c o n s e r v a t i o n . At h a r v e s t time, forages r e f l e c t growth and the environmental  the cumulative factors  r e s u l t of p l a n t  i n f l u e n c i n g the  d i s t r i b u t i o n of p h o t o s y n t h e t i c a l l y d e r i v e d energy and nutrients  i n the p l a n t (Van Soest et a l . , 1978).  Environmental composition  c o n d i t i o n s of growth determine  the p l a n t s  which i n t u r n c o n t r o l s the l i m i t s of n u t r i t i v e  value. Reviewing  l i t e r a t u r e on the n u t r i t i o n a l v a l u e of  t r o p i c a l g r a s s e s , French  (1957) concluded  of maximum energy  they are higher i n f i b r e and l i g n i n  and  lower  yield,  t h a t at the stage  i n p r o t e i n and phosphorus. They a l s o s u f f e r more  d e s i c c a t i o n l o s s e s of l e a v e s i n s i t u and a r e l e s s than  temperate g r a s s e s . Butterworth  digestible  (1967) compiled and  t a b u l a t e d a large.number of data on chemical composition and d i g e s t i b i l i t y of t r o p i c a l g r a s s e s from d i f f e r e n t p a r t s of the world. . .5  The  i n t e r a c t i o n of high temperature,  Kenyas dry season,  with p a s t u r e q u a l i t y has r e c e i v e d some  a t t e n t i o n . Working with some t r o p i c a l and D i r v e n tropical  a c h a r a c t e r i s t i c of  grass s p e c i e s , Deinum  (1975) found that the poor q u a l i t y a t t r i b u t e of  grasses  i s mainly due to the h i g h temperature i n  t h e i r e c o l o g i c a l n i c h e , and a l s o to the l a r g e n e g a t i v e e f f e c t s of age and stem f o r m a t i o n . Wilson and Minson i n d i c a t e d that grasses decrease of  digestibility  by an average  (1983)  of 0.006 u n i t s  f o r each 1°C i n c r e a s e i n temperature  over  the normal growth range. The r e d u c t i o n i n d i g e s t i b i l i t y of tropical  legumes was found  decreases  t o be much s m a l l e r with  average  of 0.0028 u n i t s of d i g e s t i b i l i t y per 1*C i n c r e a s e .  Increased temperature  was a s s o c i a t e d with an i n c r e a s e i n c e l l  w a l l c o n t e n t s and l i g n i n c o n t e n t s . The t o t a l n o n - s t r u c t u r a l carbohydrate  content of herbage decreases with h i g h e r growth  temperatures  (Wilson and Minson, 1983). I t i s g e n e r a l l y  observed  that the f a c t o r s t h a t r e t a r d p l a n t development e.g  water s t r e s s and c o l d environmental the maintenance of forage q u a l i t y  temperatures  (Van Soest et a l . , 1978).  Forage a l s o d e c l i n e s i n n u t r i t i v e v a l u e with age  a l s o promote  increasing  as i s e x p l a i n e d i n the subsequent c h a p t e r . Wilson and  Minson  (1983) however observed  that high temperatures  g r e a t e r d e t r i m e n t a l e f f e c t s on o l d e r t i s s u e dry matter ._on younger  have than  tissues.  Some experiments  on the d i g e s t i b i l i t y  of Kenyan grasses  have been c a r r i e d out ( L a k s e s v e l a and S a i d , 1978; S a i d , 1971; . .6  Van  Arkel  et  Laksesvela  a l . , 1977). The  and  Said  (1978) was  excessive  i n the  deficient  i n poor p a s t u r e  was  also  high  found  producing as  demonstrates  the  forage  e.g  be  the  that:  v i e w as  summarized  Protein  is  Kikuyu grass,  but  especially for dairy  cows. T h i s  adverse  need  seriously  cows.  Energy  f o r medium  or  nutritional situation  forages mature. C l e a r l y ,  critical  by  highly  more  d e f i c i e n t in a l l pastures  dairy  deteriorates  and  best  to  general  for correct  this  supplementation '  management.  RUMEN DEGRADABILITY OF  DIETARY PROTEIN.  Rumen m i c r o f l o r a . Dietary by  potent  1975;  and,  bound but to  endopeptidase active  one  are  degraded  p r o t e a s e s and  deaminases  (Chalupa,  of  microbial  the  located  Streptococcus  the are  than  cell  of  be  more of  content  chains  least  and  of  of  to  b o t h exo-  i n the  a  and  rumen  function protein  and  finally  1975). U n l i k e . .7  are  proteolysis,  is  of  or  b r o k e n down  t o ammonia and  are  provide  other  diet.  amino a c i d s  (Chalupa,  (Russell  surface  comprised  D u r i n g p r o t e o l y s i s most p r o t e i n s peptides,  i n at  p r o t e o l y t i c enzymes  1975). P r o t e o l y s i s  appears to  biomass  i n the  on  and  occurs  B u t y r i v i b r i o , Selenomonas,  of  (Chalupa,  cell  constituents  is rapidly  strain  substrate  p r o c e s s and  microbial  rumen  Bacteroides,  1981). Most  free access  the  1983). P r o t e o l y t i c a c t i v i t y  species,  Clostridium Hespell,  entering  rumen m i c r o b i a l  Setala,  Bacillus  cell  protein  to  carbon  deamination  an  activity  is directly  (Lewis,  1955). Amino  exceeds  the r a t e  is  r e l a t e d to dietary protein a c i d deamination  of amino a c i d  d e m o n s t r a t e d by t h e f a c t  transiently, proteins  are introduced  Proteolysis  (1981) showed almost  that  entirely  amino a c i d s  accumulate  amounts o f v e r y  digestible  thought  the p r o t e o l y t i c a c t i v i t y  associated fluid  with  p r o t e o l y s i s takes place  particles  and b a c t e r i a , w i t h  and p r o t o z o a  by i n g e s t i o n  free  amino a c i d s  f r e e amino a c i d s  and t r a n s a m i n a t i o n  mechanisms a r e t h o u g h t total  microbial  to give  nitrogen  rumen  fluid  protein  is sufficient  f o r optimum  d i e t s normally used . .8  being and  (Setala,  place These  50 t o 70% o f t h e and M i l l i g a n ,  per cent  synthesis  1982). However, on t h e f a r m s ,  protozoa  1983).  takes  (Mathison 3-8 mg  or  and  t h e few  t o about  of about  (Kaufmann and L u p p i n g ,  commercial  rise  feed  a r e then u t i l i z e d  mechanisms.  assimilated  1 9 7 1 ) . Ammonia c o n c e n t r a t i o n  of small  (Tamminga  Ammonia a s s i m i l a t i o n by rumen b a c t e r i a through amination  that  activity.  lonqinucleatum  m u l t i v e s i c u l a t u r n a r e amongst  can i n c o r p o r a t e  and  amino a c i d s  b a c k i n t o t h e s u r r o u n d i n g medium 1977). T h e s e  i n t h e rumen i s  have l i t t l e  surplus  d e g r a d e d by b a c t e r i a . E n t o d i n i u m  that  1962).  limiting  bacterial cells  Protozoal  Polyplastron  only  o f p r o t e i n s . Work by Nugent and Mangan  rumen  Hellemond,  (Lewis,  t o be t h e s t e p  cell-free  excreted  generally  by p r o t e o l y s i s . T h i s  i n t o t h e t h e rumen  i s therefore  ruminal degradation  release  that  even when l a r g e  capacity  content  i n the  of b a c t e r i a l with the  the supply  of  ammonia, and  a l s o amino a c i d s and  adequate i n meeting the  peptides  i s more than  requirements of the b a c t e r i a  (Hagemeister et a l . , 1980). Besides  ammonia, some rumen  b a c t e r i a a l s o r e q u i r e branched-chain f a t t y a c i d s , and  amino a c i d s f o r the s y n t h e s i s of m i c r o b i a l p r o t e i n  (Chalupa,  1975). Methionine and  amino a c i d s thought to be bacteria  (Orskov, 1982;  c y s t e i n e are some of  stimulatory  Chalupa,  d i e t s with nitrogen  1975;  Kaufmann and  and  ruminal  Setala  nitrogen  s p e c i f i c amino a c i d carbon-chains has  (N)  microbial protein synthesis  Lupping, (NPN)  increased  r e t e n t i o n i n growing sheep ( B r o d e r i c k ,  1975),  (Hume, 1970). Though  (1983) acknowledges s i t u a t i o n s where urea prevented  the degradation otherwise.  of feed p r o t e i n , Chalupa (1975) noted  Ruminal protozoa  o b t a i n most of t h e i r p r o t e i n  requirements by engulfment of b a c t e r i a but requirements s i m i l a r to those of higher 1966). T h e r e f o r e , effect  the  to c e r t a i n s t r a i n s of  1982). Supplementation of a l l non-protein  .,  peptides  have amino a c i d  animals  (Hungate,  i n t a c t p r o t e i n s or amino a c i d s may  have an  through s t i m u l a t i o n of p r o t o z o a l growth. Patton  (1970) observed s i g n i f i c a n t  increase  in ruminal  et a l  protozoal  numbers a f t e r supplementing sheep with methionine and i t s hydroxy analogue. Implications fact  from the above c o n s i d e r a t i o n s p o i n t to  that t o t a l p r o t e c t i o n of d i e t a r y p r o t e i n s from  degradation  may  result  i n reduced supply  ammonia f a c t o r s normally d e r i v e d . .9  ruminal  of e s s e n t i a l  from p r o t e i n  the  non-  fermentation.  The u t i l i z a t i o n dependent  of products of p r o t e o l y s i s  i s greatly  on the amount of energy a v a i l a b l e to the microbes  in the rumen. Carbohydrates are thought to be s u p e r i o r proteins  as energy sources f o r m i c r o b i a l  (Tamminga, 1979). A need t h e r e f o r e  protein  fermentation, i n f e r t i l i t y may  result (Setala,  biosynthesis  a r i s e s to balance the  d e g r a d a t i o n rate of feed p r o t e i n and the r e l e a s e from the f e e d s . In extreme  to  of energy  cases of imbalance, uncoupled problems or even ammonia  1983). The extent to which the  toxicity microbial  p r o t e i n meets the animals t o t a l p r o t e i n requirements and i t s amino a c i d p r o f i l e , determines i t s s i g n i f i c a n c e . FACTORS AFFECTING PROTEIN DEGRADABILITY IN THE RUMEN. The v a r i a t i o n i n d e g r a d a b i l i t i e s between feeds have been observed by many workers 1981; the  (Satter,  1986;  Zinn et a l . ,  Siddons and Paradine, 1981). Amino a c i d s  ruminants small  absorbed  from  i n t e s t i n e s have t h e i r o r i g i n i n the  rumen microbes, undegraded  d i e t a r y p r o t e i n , and endogenous  protein. Microbial protein  supplies  of the l a c t a t i n g cows amino a c i d s protein  of p r o t e i n degraded  i s greatly  a l t e r i n g microbial factors  the p r o t e i n  dietary  (Satter,  1986).  influenced  by the  i n the rumen.  Numerous f a c t o r s i n f l u e n c e  the  requirements, and  accounts f o r most of the remainder  Hence, the animal performance quantity  approximately two-thirds  ruminal d e g r a d a t i o n by  a c t i v i t y and access to the p r o t e i n . Among  involved  include  the extent of c r o s s l i n k i n g i n  ( d i s u l f i d e bonds), r e t e n t i o n ..10  time i n the rumen,  protein  solubility,  storage  e f f e c t s on p r o t e i n  Satter,  1986). O t h e r  and  feed  protein  intake (Clark,  and, p r o c e s s i n g  and  1975; C h a l u p a , 1975;  c h a r a c t e r i s t i c s of the p r o t e i n  p a r t i c l e i n which the p r o t e i n  resides  itself  are also  influential. Mahadevan e t a l . , (1980) showed t h a t soluble  and i n s o l u b l e )  that  became e a s i l y d e g r a d a b l e or  performic  many p r o t e i n s  were r e s i s t a n t t o d e g r a d a t i o n  after  treatment  a c i d . Mercaptoethanol  with  mercaptoethanol  and p e r f o r m i c  acid  t r e a t m e n t s have t h e s p e c i f i c  e f f e c t s of b r e a k i n g the  disulfide  Proteins  bonds  crosslinking  in proteins.  with  extensive  e.g w i t h d i s u l f i d e bonds a r e l e s s a c c e s s i b l e t o  proteolytic  enzymes a n d a r e t h e r e f o r e  degradation  (Satter,  examples of h i g h l y  1986). P r o t e i n s  crosslinked  t r e a t m e n t s have been u s e d to  degradation  relatively in hair  proteins.  Many  t o make t h e f e e d  i n t h e rumen. T r e a t m e n t  of p r o t e o l y s i s  introducing  (Satter,  d i s u l f i d e bonds  chemical  proteins  of p r o t e i n s  i n the proteins  (Mahadevan e t a l . , 1 9 8 0 ) . O v a l b u m i n  cyclic  protein  g r o u p . The c y c l i c (Satter,  1986). T h i s  tertiary  structure  Wohlt  no t e r m i n a l  feature  reduces  demonstrates  on p r o t e i n  with  reducing  the  h a s n o t been i s a s o l u b l e but  amino a c i d the rate  or  carboxyl  of p r o t e o l y s i s  the i n f l u e n c e  of the  solubility.  e t a l . , (1973) r e p o r t e d ..11  resistant  1986). The p o s s i b i l i t y o f  tested  having  r e s i s t a n t to  and f e a t h e r s a r e  formaldehyde causes methylene c r o s s l i n k i n g , thus rate  (both  that  protein  solubility is  higher  i n feeds c o n t a i n i n g  prolamins and  more albumins and  g l u t e l i n s as a major p r o t e i n  globulins  than  fraction. A  high  s o l u b i l i t y o f t e n means a r a p i d d e g r a d a t i o n of the  rumen (Crawford et a l . , 1978). Access to p r o t e i n  proteases i s greater maturity present  i n the  maturity, and  when p r o t e i n  of p l a n t s at harvest  the p r o t e i n  increases  soluble nitrogen  this  (Waldo, 1968). As  the  (Clark,  al.,  forage i s g r e a t e s t  Soest,  1977;  show that  It  proteins  (NPN)  at  from v a r i o u s  studies  maturity  differ  greatly in  feed  Crawford et a l . , 1978;  and  solubility  i s reasonable to expect p r o t e i n s o l u b i l i t y  to a group of s i m i l a r  diverse  group of  feeds d i f f e r i n g  regulate . . 12  the  may  proteins.  when  feeds than when used a c r o s s i n p h y s i c a l and  chemical  propert i e s . that  1980)  to p r e d i c t  in p r o t e i n d e g r a d a t i o n more a c c u r a t e l y  applied  Van  Mahadevan et a l . ,  be a good measure of the d e g r a d a b i l i t y of feed  Factors  proteins  (Mahadevan et  (Pichard  i n v i t r o d e t e r m i n a t i o n of p r o t e i n  differences  the  rapeseed meal were h y d r o l y z e d at about  rate of h y d r o l y s i s of c a s e i n  1980). R e s u l t s  of  in  f u r t h e r adds that  r a t e at which they are h y d r o l y z e d . S o l u b l e  o n e - f o u r t h the  solubility  forages i n c r e a s e  1975). C l a r k  content of  from soybean meal and  protein  nonprotein n i t r o g e n  except f o r c e r e a l g r a i n s . S o l u b l e the  The  type of  influences  by  f r a c t i o n s , albumin, g l o b u l i n , prolamin  g l u t e l i n decrease and  content  i s in s o l u t i o n .  a f f e c t s the  t o t a l p l a n t and  the p l a n t p r o t e i n  not  feed p r o t e i n i n  rate of  flow of  feed  a  ingredients  through the rumen i n f l u e n c e s the extent of  ruminal d e g r a d a t i o n . allows  r e t e n t i o n time i n the rumen  l e s s time f o r m i c r o b i a l f e r m e n t a t i o n .  increased the  A shorter  passage r a t e of u n d i g e s t e d forage  rumen may be a s s o c i a t e d with i n c r e a s e d  depressed d i g e s t i b i l i t y (1975) reported  that  feeding,  residue feed  ( H a r t n e l l and S a t t e r ,  reducing  i n c r e a s i n g d i e t a r y feed  In a d d i t i o n , an out of  intake and  1979). C l a r k  p a r t i c l e s i z e of the d i e t ,  intake,  increased  frequency of  and r a t e of ruminal degradation w i l l  i n c r e a s e the  r a t e of passage of d i g e s t a through the rumen. High producing ruminants consuming l a r g e q u a n t i t i e s of feed a r e l i k e l y t o have a smaller  f r a c t i o n of d i e t a r y p r o t e i n degraded i n the  rumen than animals consuming low or moderate amounts. Tamminga  (1979) working with cows consuming 8.2 or 12.9 Kg of  dry matter d a i l y  reported  29 and 45 percent  d i e t a r y p r o t e i n as a percent  undegraded  of t o t a l d i e t a r y p r o t e i n . Using  samarium sprayed hay p a r t i c l e s of d i f f e r e n t s i z e s , H a r t n e l l and  Satter  turnover  (1979) found the e f f e c t of the l e v e l of intake on  r a t e s , t o be i n s i g n i f i c a n t . Hence the impact on  p r o t e i n d e g r a d a t i o n from i n c r e a s e d passage may a l s o be minor or without e f f e c t ( S a t t e r , 1986; McAllan and Smith, 1983; Miller,  1973).  Rumen d i l u t i o n total al., the  r a t e was d e f i n e d as the p r o p o r t i o n of  rumen volume l e a v i n g the rumen per hour  ( H a r r i s o n et  1975). Some work quoted by these r e s e a r c h e r s  found that  y i e l d of b a c t e r i a dry matter per mole of ATP d e r i v e d ..13  from  rumen fermentation rate. Increasing  c o u l d be a l t e r e d by v a r y i n g the  the d i l u t i o n  dilution  r a t e of rumen f l u i d  can  i n c r e a s e the flow of p r o t e i n from the rumen of sheep and steers  ( S a t t e r , 1986). T h i s i n c r e a s e  i s a t t r i b u t e d to a net  increase  i n e f f i c i e n c y of m i c r o b i a l s y n t h e s i s  ., 1985)  and  p a r t l y due  to an  undegraded d i e t a r y p r o t e i n dilution  ( S a t t e r , 1986). Rumen  of s a l i v a  (Stokes  the ruminal  degradation  (1976) r e p o r t e d  that sheep c h a l l e n g e d  protein. It i s conceivable  with an  of c o l d exposure had  m i c r o b i a l crude p r o t e i n and  infusion  an  that  1966). Lower rumen pH, i n t a k e , may  P r o t e i n s with an  increased  i n e a r l y l a c t a t i o n , when the calories,  lactation  change i n  period.  between 5.5  and  7.0  (Hungate,  which u s u a l l y accompanies  reduce b a c t e r i a l and isoelectric  that  r e s u l t . H a r t n e l l and  (1979) d i d not however observe s i g n i f i c a n t  i s normally  increased  the amount of undegraded d i e t a r y  r a t e of d i g e s t a passage w i l l  Rumen pH  hence  i n c r e a s e d the amount of  i s m o b i l i z i n g body t i s s u e to supply  passage r a t e over the  feed  and,  i n f l u e n c e passage r a t e and  r a t e of d i g e s t a passage. T h i s  Satter  intakes,  i s the c a l o r i c demand. Kennedy e_t  c a l o r i c demand as a r e s u l t  increased  fluid  feed  et a l . , 1985)  of  (Harrison et a l . , 1975).  Another f a c t o r that may  cow  et a l  i n the p r o p o r t i o n  r a t e s have been i n c r e a s e d by h i g h  i n c l u s i o n of sodium s a l t s  al.  increase  (Stokes  point  increased  proteolytic activity.  in the  range would then have reduced s o l u b i l i t y ..14  normal rumen ( S a t t e r , 1986)  pH and  possibly altered protein degradability also. Feed p r o c e s s i n g and  methods such as p e l l e t i n g ,  steam r o l l i n g and  a l t e r p r o t e i n and  f l a k i n g may  generate enough heat  either increase  or decrease  d e g r a d a t i o n of p r o t e i n s . D i s r u p t i o n result  in increased  grain processing  (Chalupa,  1975). Some p r o c e s s i n g  microbial  protein production  by  starch  fermented i n the  Satter  (1986) show that as heat  In many in v i t r o and  et a l . , 1983; extent  can  a c h i e v e the  procedures  input  applied opposite  the q u a n t i t y  of  worked out  to a feed  is  by  increased,  increases.  RUMINAL PROTEIN DEGRADATION. in s i t u experiments, p r o t e i n  been d e s c r i b e d  Orskov and  as a f u n c t i o n of  McDonald, 1970;  time  Lindberg,  rumen microbes and  (Weakley  1984).  of d e g r a d a t i o n determines both the degradable f o r the  which may  be a v a i l a b l e f o r host animal enzymic d i g e s t i o n . methods of o b t a i n i n g  d e g r a d a b i l i t y are  Orskov, i n the  1980), or by  q u a n t i t a t i v e e s t i m a t e s of  the abomasum (De  incubating  rumen f o r f i x e d d u r a t i o n s  Orskov et a l . , 1980)w The difficulties  the undegraded p r o t e i n  used, namely, measuring the q u a n t i t y  dietary protein entering  of m a i n t a i n i n g ..15  The  part  available  Two  may  increase  rumen. R e l a t i o n s h i p s  TECHNIQUE AND  d e g r a d a t i o n has  ruminal  p r o t e i n matrix  increasing  the amount of undegraded p r o t e i n NYLON BAG  of the  to  ruminal d e g r a d a t i o n , whereas heat  or generated during  THE  extrusion,  first  of  Boer et a l . ,  dietary protein (Orskov and  i n nylon bags  McDonald,  method i n v o l v e s  s u r g i c a l l y prepared  1986;  the animals,  1970;  requires  lengthy  uncertainty dietary bag,  as  series  to the  p r o t e i n . The  rumen bag)  provides  of a n a l y s e s ,  accurate  i s subject  and  (dacron  fibre  bag,  artificial  d e s c r i b e d by O r s k o v  u s e f u l i n f o r m a t i o n on  to  s e p a r a t i o n of m i c r o b i a l  nylon-bag  technique  and  both  the  e t a l . (1980)  extent  and  r a t e of  degradation. Most d a t a with  on  protein degradation  three p r o t e i n pools  nitrogen  (Satter,  or p r o t e i n t h a t  protein  degraded at a r a t e s i m i l a r  digesta  passage  0.2  hour).  per  very  slowly  degradation constant unit be  of  or not  C,  at a l l .  rate that  time.  techniques different  by  exist  i s assumed  reticulorumen constants.  the  flow and  P i c h a r d and  griseus  protease  forages  include a rapidly  slowly  degradable  and  Van  r a t e of 0.02  to  a is, a  B protein  per  will  Various  estimates rate  (1975) r e v i e w e d  of  the  constants. the  use  of  points  in  the  useful estimates  of  various  that  (1977) u s e d insoluble  degradable  fraction. ..16  has that  of p o o l  reasonable  Soest  found  B,  p r o t e i n i s degraded  relevant fractional  provide  Pool  (approximately  each p o o l  of d i g e s t a at g i v e n  can  protein  fractional  r a t e of passage.  Faichney  non  rapidly.  fractional,  remaining  that provide  (1982) and  to the  the  A,  model  u n a v a i l a b l e p r o t e i n degraded  Ideally,  relative  p o o l s and  Orskov  to the  Also, only degradation the  very  reticulorumen  bound or  p r o p o r t i o n of  affected  markers  Pool  a general  1986): P o o l  i s degraded  from the  fits  Feeds  Streptomyces  p r o t e i n s of  fraction  and  some  a more  t h e r e f o r e seem t o c o n t a i n  s e v e r a l types of p r o t e i n that are presumably each p r o t e i n has r a t e . The  i n the B f r a c t i o n ,  i t s own  fractional  degradation  d i f f i c u l t i e s of measuring the f r a c t i o n a l r a t e s in  pool B are q u i t e  evident.  E x i s t i n g procedures i n c l u d i n g that d e s c r i b e d et  a l . (1980) f a i l  to s o r t out  do y i e l d an average r a t e . The 'P'  and  a f t e r a time ' t ' hours may P = a + b(1  - e~ )  i n d i v i d u a l r a t e constants percentage of m a t e r i a l be d e s c r i b e d (i)  ct  by Orskov but  degraded  by the  equation;  [Orskov et a l . ,  1980]. where, P = the a c t u a l d e g r a d a t i o n a f t e r time ' t ' , t = the  incubation  time i n hours,  a = the  i n t e r c e p t of the degradation curve at time  b = the p o t e n t i a l d e g r a d a b i l i t y of the component will,  i n time, be c = the Pool  A, as measured by  s o l u b l e p r o t e i n s and  f o r the d e g r a d a t i o n of  p r o t e i n s r e s i d i n g in very  that s o l u b l e p r o t e i n from f i s h meal was  small  i s incubated  amylophilus hydrolyzed  r a t e of h y d r o l y s i s of s o l u b l e p r o t e i n s  soybean meal or rapeseed meal. These r e s u l t s p o i n t  and  (%/hr).  and/or  ( S a t t e r , 1986). Mahadevan et a l . (1980)  working with the protease in Bacteroides  fact  'b'  t h i s technique, c o n s i s t s of  p a r t i c l e s that are removed when the bag  double the  that  degraded.  r a t e constant  washed f o r 1 hour  zero,  found  at about from to  the  t h a t , not a l l s o l u b l e p r o t e i n s are degraded in the rumen vice  versa.  . . 17  Only the  the  relative  degradation  pool  (  p e  effective  ff) is;  = a + b c / ( c + k)  f f  B p r o t e i n i s a f f e c t e d by  r a t e of p a s s a g e . T h e r e f o r e  degradability P  of  ( i i ) [Orskov  et a l . ,  1980]  where, a,b  and  c are  k = relative degradability represents in  the  of  the  given  in equation  r a t e of p a s s a g e the  sample  fraction  pool  i s given  which w i l l  in s i t u  bag  technique  subject  t o a number of  Weakley  e t a l . , 1983): The  breakdown due the  breakdown and  of  by  B.  and  Since  the  (a+b), t h e n  appear  t o be  total  l00-(a+b)  undegradable  rumen.  The  within  ( i ) above,  not  of a  sample  to a  able  the  to leave  s t u d i e s on;  surface  area  effects  have been c a r r i e d  in  degradation  ratio,  Setala,  1983;  washing  technique  recently  size  i s not  small  exposed since  any  for  leave  simple  b r o k e n down f e e d  the  the  bag  chemical  particles  rumen. bag  substrate out  pore  size,  particle  sample w e i g h t ,  size  to determine  measurements  (Orskov  and, their  et a l . ,  Weakley e t a l . , 1983). V a r i a b i l i t y was  to  i t is confined  enough t o to  is  1980;  t h e r e f o r e , are  degradation  suitably the  et a l . ,  rumination  n e c e s s a r i l y a complete  Extensive  situ  sample  Measurements o b t a i n e d  compounds. N o r m a l l y would be  many s h o r t c o m i n g s and  v a r i a b l e s (Orskov  t o c h e w i n g and  bag.  has  recognized  by  animal  bag diet  influence  on  1980; due  to  Weakley e t a l . (1983)  De-Boer e t a l . (1986) d e s c r i b e d a m o d i f i e d . . 18  and  and  more  c o n s i s t e n t method. Uden et a l • (1974) observed a r e d u c t i o n i n s u b s t r a t e disappearance as a r e s u l t of d e c r e a s i n g bag pore  size.  G r e a t e r d i g e s t i b i l i t y of Guinea grass from nylon bags with a 53-nm pore s i z e was observed as compared to 20- or 35-nm p o r o s i t y bags. Weakley et a l . (1983) observed a g r e a t e r disappearance of dry matter and n i t r o g e n and d i s t i l l e r s g r a i n s with dacron r i p - s t o p nylon bags (no v i s i b l e  from soybean meal  (52-nm pore s i z e ) than from  p o r e s ) . These d i f f e r e n c e s are  deemed to have been due to l a r g e r p o r o s i t y m a t e r i a l s a l l o w i n g g r e a t e r e f f l u x of d i g e s t e d r e s i d u e s . Other r e s e a r c h e r s (Uden et a l . , 1974; Nocek et a l . , 1979) have observed gas accumulation  i n bags with pore s i z e s ranging from 20- to  35nm, r e s u l t i n g differential  in limited d i g e s t i b i l i t y  i n s i t u . The  p r e s s u r e s and tumbling f i b r o u s mat may be  r e q u i r e d to remove o b s t r u c t i o n s , such as the p a r t i c u l a t e matter or b a c t e r i a l s l i m e , from the pores of s m a l l pore bag m a t e r i a l s , and thus p r e v e n t i n g gas accumulation w i t h i n the bag  (Weakley  et a l . ,  1983).  The optimum s i z e of bag i s determined by the n e c e s s i t y to have the bag l a r g e enough r e l a t i v e to the sample  size  used. T h i s ensures that rumen f l u i d can e a s i l y enter the bag and mix with the sample (Orskov et a l . , 1980). A l s o , the bag need be small enough, to be e a s i l y withdrawn  through the  rumen cannula. I d e a l l y the sample prepared f o r i n c u b a t i o n should . . 19  represent after  the  materials  i n g e s t i o n by  the  oesophageal cannula, screen,  chopping,  used  reduce  to  particle unit  size  weight  substrate  size  of  the  substrate  would be  to m i c r o b i a l  has  should  As  the  reduced  subject  of  i n the  Based  later  on  of  of  the  are  mm  usually  Decreasing surface  area  particles  l e s s than  comparisons a  per  the  However Weakley  amount of  bag  size  et a l . 0.6  mm  degradation  consistent  the  bags  sample  i n the  results.  necessary  these  variability  to weights  so  been  the  digestion  was  Johnson,  e t a l . (1980) c o n c l u d e d little  as  no  to anchor  25cm of  i n the reduced  nylon  cord  1950).  that  effect  disappearance  rumen. V a r i a t i o n between bags was  b a g s were a n c h o r e d w i t h a b o u t . .20  or  workers d i d not  i n DM  should  incubation.  ( B a l c h and  rumen had  Further,  increased  a l . , 1980).  rumen has  Increased  sac  was  (Orskov et  for analysis after  bags i n t h e  when a t t a c h e d  of  observed  work, O r s k o v  i n the  3.0  r e s u l t i n g in decreased  rumen v e n t r a l  degradation.  reduction  size.  increase  for a given  smallest  conflicting  reported  grinding  in s i t u .  reasonable  sample s i z e  the  to  from  maintained.  p o s i t i o n of  position  -  be  For  to  2.5  rumen  i n c r e a s i n g e x p o s u r e of  clumping  adequate m a t e r i a l The  feed  attack  d e g r a d a b i l i t y was  Apparently, yield  thus  been o b s e r v e d ,  and  i n the  ingesta  through  particle  expected  substrate,  substrate.  method  animal. Masticated  hammermilling  (1983) i n d i c a t e s t h a t in  t h e y would a p p e a r  cutting, rolling  the  of  as  the  on  notice  any  between  bags  ventrar~~sac when the to  the  the  cannula  top  (Orskov,  i n s h e e p and  1982;  Orskov  w i t h about  e t a l . , 1980;  Weakley e t a l . , 1983). Some  have u s e d  pebbles the  and  rumen The  the  (Orskov  i n c u b a t i o n p e r i o d be  total  time  f o r complete  being  i n c u b a t e d , and  other  an  the  bags  (De  e t a l . , 1986;  B o e r e t a l . , 1986).  bottles  t h e bags  rate  spread  filled  with  i n the v e n t r a l  of d e g r a d a t i o n over  degradation  hence the  a d e q u a t e and  Orskov  sensitive  cattle  sac  of  e t a l . , 1980).  measurement of  description,  Boer  s i n k e r s (250ml p l a s t i c  water) to p o s i t i o n  a l s o v a r y . For  De  in  w o r k e r s have e m p l o y e d p o l y e s t e r  mesh bags t o c o n t a i n s m a l l n y l o n Others  50cm o r more  a specified varies  with  period.  reliable  the curve  be  The  the m a t e r i a l  intermediate times  chosen  will  mathematical  (1982) recommends t h a t  p a r t s of  requires that  well  the asymptote supported  and  by  observations. The should be  diet  be  similar  applied.  protein slowly  given to the animals  that and  origin  with nylon the  results  bags are  (1982) i n d i c a t e d were d e g r a d e d  to that  more  g i v e n a h i g h - c o n c e n t r a t e a s compared w i t h a  diet.  Working w i t h  Weakley  Orskov  s u p p l e m e n t s of v e g e t a b l e in animals  matter  f o r which  R e s u l t s o b t a i n e d by  high-roughage  found  to the d i e t s  fitted  s h e e p on  animals  b a r l e y , Orskov  c o n t r i b u t e d the h i g h e s t v a r i a t i o n  nitrogen disappearance  e t a l . , (1983) o b s e r v e d  (P<0.05) i n i n s i t u  et a l . (1980),  dry matter . .21  no  from  in situ  significant  disappearance  in dry  b a g s . However, difference  among t h e  four  cows t h e y f e d w i t h s o y b e a n degradation  of n i t r o g e n  significance therefore  (P<0.10)  physically  from s o y b e a n  at  concluded that  with animal e f f e c t s similar  meal. D i f f e r e n c e s  12  i t may  t o soybean  .22  approached  hours of i n s i t u  on i n s i t u  .  meal  among cows i n  exposure.  They  be n e e d l e s s t o be c o n c e r n e d measurements f r o m  meal.  substrates  MATERIALS AND METHODS  Two mature A y r s h i r e s t e e r s f i t t e d  with a permanent rumen  cannula were used. The animals were f e d twice d a i l y with alfalfa  cubes and o r c h a r d g r a s s hay a t 50:50 r a t i o (dry  b a s i s ) . The feed was o f f e r e d ad l i b i t u m the  morning  i n two sequences, i n  and a f t e r n o o n .  Forage samples were c o l l e c t e d a f t e r the long r a i n s  (Table  i n the Kenya Highlands  1). Sample c o l l e c t i o n and  p r e p a r a t i o n methods used a r e o u t l i n e d by H a r r i s l e a s t t e n sampling l o c a t i o n s were e s t a b l i s h e d  (1971). At  i n the f i e l d  and 2.5kg of f r e s h m a t e r i a l o b t a i n e d . A l l samples were d r i e d at  60 t o 70°C f o r 48 t o 72 hours and ground through a 2mm  screen. The method used i s as o u t l i n e d by Orskov et a l . (1980).Dacron bags,  ( 5 * 1 1 cm) made from nylon and having  40nm diameter pore s i z e , were used throughout the study. Sample s i z e s and i n c u b a t i o n  i n t e r v a l v a r i e d w i t h the type of  m a t e r i a l under study as o u t l i n e d by Orskov e t a l . (1980). Dacron bags with t e s t m a t e r i a l were incubated i n the rumen. The i n t e r v a l between i n c u b a t i o n s was 6 hours, with  1 hour  (Satter,  starting  1986). T h i s was f o l l o w e d by 6, 12,  l8,...upto 72 h o u r s ^ i n c u b a t i o n p e r i o d s . A l l samples were incubated a t l e a s t  i n d u p l i c a t e . R e s u l t s that v a r i e d  (CV >15%) were repeated. A 10 cm long s t r i n g t i e d . .23  markedly  individual  bags on to a 50 cm main s t r i n g . The  bags were p o s i t i o n e d i n  the v e n t r a l sac of the rumen with the h e l p of a s i n k e r (plastic to  bottle f u l l  of sand and water). The  the t i p of the main Immediately a f t e r  s i n k e r was  string. retrieval  were soaked i n a r e s e r v o i r C a r e f u l hand washing was  full  from the rumen, the bags of c o l d water f o r 5 minutes.  done f o r 10 to 15 minutes to remove  rumen f l u i d and any d e b r i s s t i c k i n g on the bags. The m a t e r i a l was and, was  then  thumb  i n the c o l d water. C l e a n l i n e s s of the bags  then a s c e r t a i n e d by u s i n g the running tap  (Orskov  bag  cleaned by rubbing between the f i n g e r and  rinsing  tied  et a l . 1980). The  procedure  bags were then d r i e d  60-70°C f o r 48-72 hours. DM  i n an oven at  and CP contents were then  determined. All Allen,  samples were analysed f o r DM,  1975)  NDF  and ADF  (Chapman and P r a t t ,  (Waldern,  1961)  CP  1971)  (Parkinson and  total  before i n c u b a t i o n . A f t e r  and d r y i n g , the samples were again a n a l y s e d f o r DM The  General L i n e a r Model of the SAS  (1985) was  used  e x p e r i m e n t a l model employed was (forage samples) f a c t o r i a l The  treatment  and  the  e f f e c t was  a 12(incubation  i n a completely  rinsing and  The time)*32  randomized d e s i g n . effect  i n t e r a c t i o n e f f e c t between  the forage samples was .24  CP.  Package  composed of the forage sample  i n c u b a t i o n time e f f e c t . An  i n c u b a t i o n time and  ash  Statistical  f o r a l l s t a t i s t i c a l comparisons.  and  also tested for.  Table  1:Names and stage of h a r v e s t i n g of the forage samples.  SAMPLE NAME:  GROWTH STAGE.  FODDER GRASSES. (EV Giant Panicum E a r l y vegt. (EV E d i b l e Canna E a r l y vegt. (EV Guatemala grass E a r l y v e g t . (EV P a k i s t a n i h y b r i d E a r l y vegt. (EV French Cameroon E a r l y vegt. (EV Clone.13 E a r l y vegt. Clone.13 Regr. flower (RF (EV Bana g r a s s E a r l y vegt. (RV Bana g r a s s Regr. vegt. Bana g r a s s Regr. flower (RF (MS Green Maize chop M i l k stage (LV Fodder Sorghum Late v e g t . (FB Fodder Sorghum F u l l bloom PASTURE GRASSES. Kikuyu grass Regr. flower (RF P. trachyphyllum Regr. flower (RF (LV Late vegt. Stargrass (FB F u l l bloom Stargrass (MB Mid bloom Red Oat grass (LB Late bloom Red Oat grass (MB Mid bloom Rhodes grass (LB Late bloom Rhodes grass LEGUMES. (EV E a r l y vegt. Lucerne (MB Mid bloom Lucerne (MB Mid bloom Lucerne (LB Late bloom Lucerne (ES E a r l y seed Desmodium spp. CROP RESIDUES, (EV E a r l y vegt. Rhubarb leaves Regr. flower (RF Banana l e a v e s (PR Maize s t o v e r Post r i p e Wheat bran Wheat straw (PR Post r i p e Sweet Potato v i n e s Regr.flower(RF [Vegt.-Vegetative  SCIENTIFIC NAME. Panicum a n t i d o t a l e Canna e d u l i s Tripsacum f a s c i c u l a t u m Pennisetum purpureum P. purpureum P. purpureum P. purpureum P. purpureum P. purpureum P. purpureum Zea mays Sorghum sudanense S. sudanense Pennisetum clandestinum Pennisetum trachyphyllum Cynodon p l e c t o s t a c h y u s C. p l e c t o s t a c h y u s Themeda t r i a n d r a T. t r i a n d r a C h l o r i s qayana C. gayana Medicago s a t i v a M. s a t i v a M. s a t i v a M. s a t i v a Desmodium uncinartum Rheum rhabarbarum Musa s p e c i e s Zea mays T r i t i c u m eastivum T. aestivum Ipomoea batatas  Regr.-Regrowth  .25  Flower  -Flowering]  RESULTS  Chemical c o m p o s i t i o n . Clone. 13 and bana g r a s s v a r i e t i e s dropped markedly i n q u a l i t y between the v e g e t a t i v e and the f l o w e r i n g stage 2).  T h i s was  marked by a f a l l  i n c r e a s e in both ADF  and NDF  i n the CP content and  of  than the other fodder  n e g a t i v e e f f e c t s of m a t u r i t y on the chemical maize and  percentage  sorghum was  an  c o n t e n t s . Green maize chop and  sorghum were of higher q u a l i t y The  grasses.  composition  c h a r a c t e r i s e d by a drop of over  p o i n t s i n the CP c o n t e n t s , between the two  sampled. The  cell  (Table  w a l l contents  five  stages  i n c r e a s e d over the same  per i o d s . Pasture grasses were g e n e r a l l y of lower q u a l i t y  than  the fodder ones. D e c l i n e s i n q u a l i t y were a l s o observed  with  matur i t y . Lucerne  and desmodium tended  to remain h i g h i n CP  content over the sampled p e r i o d . A high p r o p o r t i o n of w a l l c o n t e n t s was  observed  A great v a r i a t i o n  cell  i n desmodium.  i n chemical composition  w i t h i n the v a r i o u s crop by-products  existed  sampled. Rhubarb l e a v e s ,  sweet potato v i n e s , banana l e a v e s and wheat bran were high in CP c o n t e n t . Maize s t o v e r and wheat straw were h i g h i n c e l l wall contents. It  may  be d e s i r a b l e to compare s t a t i s t i c a l l y ,  v a r i o u s degradation r a t e c o n s t a n t s . .26  the  (a,b and c ) . However, the  Table 2:Chemical c o m p o s i t i o n of forage SAMPLE NAME. FODDER GRASSES. Giant panicum E d i b l e canna Guatemala grass Pakistani hybrid French Cameroon Clone.13 Clone.13 Bana grass Bana grass Bana grass Green maize chop Fodder sorghum Fodder sorghum PASTURE GRASSES. Kikuyu grass P. trachyphyllum Naivasha s t a r g r a s s Naivasha s t a r g r a s s Red oat grass Red oat grass Rhodes grass Rhodes grass LEGUMES. Lucerne Lucerne Lucerne Lucerne Desmodium CROP RESIDUES. Rhubarb l e a v e s Banana leaves Maize stover Wheat bran Wheat straw Sweet potato v i n e s  AGE  %DM  EV EV EV EV EV EV RF EV RV RF MS LV FB  92 .45 93 .25 91 .91 94 .38 94 .45 93 .84 94 .04 94 .49 93 .75 93 .51 92 .07 92 .87 93 .83  RF RF LV FB MB LB MB LB EV MB . MB LB ES EV RF PR PR RF  .27  %CP 8. 47 14. 91 12. 1 0 9. 45 7. 36 16. 64 4. 1 1 9. 18 10. 83 6. 92 14. 16 17. 34 1 1 .68  samples.  %ADF  %NDF  %ASH  49. 75 48. 75 50. 02 47. 74 51 . 32 40. 09 58. 99 44. 41 54. 94 49. 90 40. 15 36. 47 44. 38  73. 47 70. 67 74. 37 71 . 43 78. 40 64. 89 84. 69 68. 05 75. 05 74. 21 69. 31 65. 35 75. 25  16. 12. 13. 22. 24. 19. 9. 20. 13. 13. 12. 13. 10.  94 .43 13. 80 94 .85 1 1 74 . 94 .42 7. 1 4 94 . 1 2 6. 1 4 94 .90 5. 70 94 .74 5. 21 93 .93 5. 93 94 .36 8. 29  35. 44. 53. 49. 48. 54. 46. 48.  78. 77. 80. 85. 80. 82. 79. 85.  99 27 80 89 51 68 46 99  15. 76 16. 78 12. 84 7. 99 9. 32 9. 82 10. 45 10. 85  93 93 93 92 93  34 08 48 53 16  15. 12. 10. 14. 8.  30 46 97 18 85  13. 13. 8. 5. 10. 17.  02 17 27 97 99 93  58 08 31 86 69 40 90 04  .33 .18 .64 .71 .38  20. 22 18. 78 19. 19 21 . 97 15. 84  38. 86 38. 1 4 41 . 30 43. 38 60. 44  55. 58. 55. 56. 70.  91 .72 94 .46 94 .95 92 .72 94 .03 92 .33  14. 02 15. 42 5. 39 16. 09 5. 72 20. 53  18. 39. 49. 19. 50. 39.  23. 22 75. 74 81 . 50 58. 60 73. 22 42. 63  59 44 25 26 21 73  53 63 98 94 08 09 08 57 30 84 54 24 83  relatively makes t h e results  small  analysis  discussed  significantly degradation forage  number o f of  data  points  incubation  t i m e and  (P<0.05) i n f l u e n c e d rumen. The  s a m p l e s and  in this  study  a d d i t i o n a l parameters d i f f i c u l t .  below  i n the  measured  the  the  extent  incubation  the  sample e f f e c t of  sample  interaction effect  time of  In  was  between  not s i g n i f i c a n t  (P<0.05).  Fodder  grasses.  Figure fodder explain During  1 shows a t y p i c a l  grasses. DM  The  and  the  CP  first  degradation  R-squared values  degradability 36  hours  the  were 86  3 and  4 show t h e  Clone.13, P a k i s t a n i m o d e r a t e DM of  CP  DM  the  protein  rapidly soluble  degradable  protein  the  protein 'b'  CP  edible  solubilities  and  and  (P<0.05)  and  and  growth. These r e p r e s e n t e d  between The  and  hybrid  the  93%  in  constants.  canna v a r i e t i e s  a proportional non-nitrogenous  f r a c t i o n of  giant  the  early  components.  the  potentially  and  panicum  and  effective  for giant  significantly higher  rates  contributed  DM  degradation  (P<0.05) h i g h e r of  DM  and  CP  p o s i t i v e l y to  than  panicum  f o r Guatemala  degradation  'c'  for  5 and  6,  was grass.  giant  this effect. Pakistani  . .28  stage  feed  s i m i l a r . From T a b l e  and  had  solubility  G u a t e m a l a g r a s s were r e l a t i v e l y CP  to  respectively.  degradation  'a'  for  established.  (15-20%) a t  fraction  obtained  model u s e d  major d i f f e r e n c e s  d i s a p p e a r a n c e were s i g n i f i c a n t l y Table  for  curve  The  panicum  hybrid  had  a  F i g 1:  % Degradation Versus incubation Time, Green Maize Chop.  100  c  Q 0  o  •s o  D  % DM Degraded.  Time Incubated in the Rumen [Hrs]. * * graded. C  29  P  Table 3: Dry Matter Degradation SAMPLE NAME.  AGE  FODDER GRASSES. G i a n t panicum E d i b l e canna Guatemala grass Pakistani hybrid French Cameroon Clone.13 Clone.13 Bana grass Bana grass Bana grass Green maize chop Fodder sorghum Fodder sorghum PASTURE GRASSES. Kikuyu grass P. trachyphyllum Naivasha s t a r g r a s s Naivasha s t a r g r a s s Red oat grass Red oat grass Rhodes grass Rhodes grass LEGUMES. Lucerne Lucerne Lucerne Lucerne Desmodium CROP RESIDUES. Rhubarb leaves Banana leaves Maize s t o v e r Wheat bran Wheat straw Sweet potato v i n e s  Constants.  a  b  EV EV EV EV EV EV RF EV RV RF MS LV FB  14.,44 22..22 13..33 15.,55 16.,66 17..77 10.,00 16.,66 18. .88 1 1 .. 1 1 32,.22 24..44 15..55  45..56 43..33 54.,44 46..67 48.,89 55..56 46.,66 51 ..1 1 55..56 50,.00 48..89 54,.44 48..89  4.,9 3.,2 2.,8 5.,4 4.,0 4., 1 3..6 6., 1 4..9 4..9 4..3 5.; 1 4..6  RF RF LV FB MB LB MB LB  21 ..1 1 21 ., 1 1 12..22 10..00 10..00 8,.88 10..00 16..66  55,.55 54..44 47,.77 31 ., 1 1 47,.77 44,.45 47,.77 43,.90  4.,7 6..2 4.,0 3..5 3..8 3..8 3..8 4..7  EV MB MB LB ES  25..55 23..33 24,.44 24.. 44 13,.33  43,.33 44,.44 36,.67 37,.78 36,.66  6..8 5,.5 10,.9 4,.0 3,.4  EV RF PR  20..00 21 ., 1 1 1 1 ., 1 1 25,.55 12,.22 27,.77  69,.99 28,.89 48,.88 47,.78 45,.55 50,.00  6,.7 3,.8 3,.4 8,.9 3,.3 7,.9  PR RF  a= % s o l u b i l i t y , b= p o t e n t i a l l y degradable c= r a t e of degradation of the 'b' f r a c t i o n  .30  f r a c t i o n [%], [%/hr].  Table 4: Crude P r o t e i n Degradation SAMPLE NAME. FODDER GRASSES. Giant panicum E d i b l e Canna Guatemala grass Pakistani hybrid French Cameroon Clone.13 Clone.13 Bana grass Bana grass Bana grass Green maize chop Fodder sorghum Fodder sorghum PASTURE GRASSES. Kikuyu grass P. trachyphyllum Naivasha s t a r g r a s s Naivasha s t a r g r a s s Red oat grass Red oat grass Rhodes grass Rhodes grass LEGUMES. Lucerne Lucerne Lucerne Lucerne Desmodium CROP RESIDUES. Rhubarb l e a v e s Banana leaves Maize s t o v e r Wheat bran Wheat straw Sweet potato v i n e s  AGE  Constants.  a  EV EV EV EV EV EV RF EV RV RF MS LV FB  12..22 18,.89 12,.22 21 ., 1 1 7,.00 18,.89  b 54,.45 44..44 58,.89 46,.67 63,.00 61 ., 1 1  7..0 1 .6 . 2..2 0..4 4..0 6..0  1  l\.22  70! .56 53,.89 65,.00 55,.56  6!.6 0,.9 3,.2 8,.6  1 1 .67 ,  58!.33  6!.6  RF RF LV FB MB LB MB LB  20,.00 20,.00 10,.00 7,.78  60,.00 60,.00 65,.56 46,.66  7,. 1 4,.7 1 ., 1 3,.3  10,.00 8,.00 14,.44  57!!78 50,.00 51 .. 1 2  2,!s 6,.4 2,. 1  EV MB MB LB ES  18. .33 20,.00 20..00 20,.00 1 1 .,1 1  60..00 65..56 60,.00 53..89 51 .67 .  9,. 1 6,.2 6,.5 7,.7 4,.0  EV RF PR  65,.56 22..78 7..22 8..33 7.,83 21 .. 1 1  21 .. 1 1 35..00 50..56 53..34 72..78 62..22  6..6 3,.9 6,.2 6,.2 7..6 4..8  PR RF  9,.44 13,.89 22,.22 »  K>  a= % s o l u b i l i t y , b= p o t e n t i a l l y degradable c= r a t e of degradation of the 'b' f r a c t i o n  .31  f r a c t i o n [%], [%/hr].  Table SAMPLE  5: E f f e c t i v e  NAME.  AGE  FODDER GRASSES. G i a n t panicum E d i b l e canna Guatemala grass Pakistani hybrid F r e n c h Cameroon Clone.13 Clone.13 Bana g r a s s Bana g r a s s Bana g r a s s Green maize chop F o d d e r sorghum F o d d e r sorghum PASTURE GRASSES. Kikuyu grass P. t r a c h y p h y l l u m Naivasha s t a r g r a s s Naivasha s t a r g r a s s Red o a t g r a s s Red o a t g r a s s Rhodes g r a s s Rhodes g r a s s LEGUMES. Lucerne Lucerne Lucerne Lucerne Desmodium CROP RESIDUES. Rhubarb l e a v e s Banana l e a v e s Maize stover Wheat b r a n Wheat s t r a w Sweet p o t a t o v i n e s k= rumen d i g e s t a f l o w  Dry M a t t e r k = 0. 03  Degradation. 0. 04  0. 05  0. 06  0 .07  EV EV EV EV EV EV RF EV RV RF MS LV FB  42. 70 44. 56 39. 61 45. 55 44. 60 49. 85 35. 45 50. 92 53. 34 42. 1 2 61 . 02 58. 72 45. 1 4  39. 52 41 .48 35. 75 42. 36 44. 1 1 45. 89 32. 10 47. 53 49. 47 38. 64 57. 55 54. 95 41 .70  36. 99 39. 1 3 32. 87 39. 78 38. 39 42. 80 29. 53 44. 75 46. 38 35. 86 54. 83 51 .93 38. 98  34. 37. 30. 37. 36. 40. 27. 42. 43. 33. 52. 49. 36.  RF RF LV FB MB LB MB LB  55. 57. 39. 57. 36. 33. 32. 43.  02 80 43 30 70 72 68 46  51 .1 2 54. 20 36. 42 53. 28 33. 27 30. 54 30. 41 40. 38  48. 03 51 .25 33. 38 49. 89 30. 63 28. 07 28. 57 37. 93  45. 51 48. 78 31 . 24 46. 99 28. 52 26. 1 2 27. 05 35. 94  43 .42 46 .68 29 .51 44 .49 26 .81 24 .52 25 .78 34 .30  EV MB MB LB ES  55. 62 53 .20 52. 09 46. 03 32. 81  52. 83 51 .27 49. 06 43. 33 30. 1 7  50. 52 49. 58 46. 61 41 .23 28. 1 7  48. 48. 44. 39. 26.  57 09 58 55 59  46 .90 46 .77 42 .88 38 . 18 25 .32  EV RF PR  68. 34 37. 25 37. 08 61 . 28 36. 08 64. 01  63. 35. 33. 58. 32. 60.  60. 33. 30. 56. 30. 58.  56. 32. 28. 54. 28. 56.  92 31 79 09 38  54 .23 31 .28 27 .09 52 .29 26 .81 54 .28  PR RF rate  .32  [%/hr].  83 18 57 51  81  96  08 59 89 1 4 33 39  92 29 65 66 22 32 50 43 86 59 63 45 77  19  33 .20 35 .81 28 .88 35 .87 34 .55 38 .29 25 .85 40 .46 41 .76 31 .70 50 .82 47 .39 34 .94  Table 6: E f f e c t i v e Crude P r o t e i n D e g r a d a b i l i t y . 5AMPLE NAME.  AGE k= 0.03  FODDER GRASSES. Giant panicum E d i b l e canna Guatemala grass Pakistani hybrid French Cameroon Clone.13 Clone.13 Bana grass Bana grass Bana grass Green maize chop Fodder sorghum Fodder sorghum PASTURE GRASSES. Kikuyu grass P. t r a c h y p h y l l u m Naivasha s t a r g r a s s Naivasha s t a r g r a s s Red oat grass Red oat grass Rhodes grass Rhodes grass LEGUMES. Lucerne Lucerne Lucerne Lucerne Desmodium CROP RESIDUES. Banana leaves Rhubarb leaves Maize stover Wheat bran Wheat straw Sweet potato v i n e s  EV EV EV EV EV EV RF EV RV RF MS LV FB  50. 34. 37. 27. 43. 59.  0. 04 34a 76hs 45h 67f 20e 69t  0 .05  46. 88 31 . 96 33. 41 26. 20 38. 71 55. 62  0 .06  0 .07  99 00 49 28 20 28  41 .55 28 .55 28 .28 24 .63 32 .40 49 .51  39. 27. 26. 24. 30. 47.  51 . 23 47. 44 19. 43 17. 73 42. 86 39. 34 60. 1 3 57. 34  44 !26 16 .53 36 .58 54 .94  41 . 54 15. 64 34. 35 52. 84  51 . 94qa 48. 1 7 45. 05  42 .42  40 ! 18  RF RF LV FB MB LB MB LB  62. 56. 28. 32.  52 46 20 24  50. 44. 19. 22.  38. 1 1h 34. 00 42. 1 6he 38. 90 35. 64hs 32. 18  30. 94 36. 20 29. 69  28 .57 33 .94 27 .81  26! 68 32. 02 26. 35  EV MB MB LB ES  63. 54xm 64. 22m 61 . 24xm 58. 88t 59. 60tx  60. 59. 57. 55. 55.  1 1 89 35 58 26  57. 1 6 56. 34 54. 1 3 52. 79 51 . 80  54 .60 53 .36 51 .42 50 .41 48 .98  52. 50. 49. 48. 46.  RF EV PR  40. 84b 80. 1 Op 42. 65e 41 . 29h 44. 43eg 82. 22p  37. 78. 40. 37. 40. 79.  15 73 15 95 92 13  34. 77. 38. 35. 38. 76.  31 76 36 32 35 73  •  #  55. 79q 21 . 98nf 47. 52g 63. 40x  43. 30. 30. 25. 35. 52. •  •  31 tx 83t 60fs 32hs  58. 52. 25. 28.  •  PR RF  53 63 01 97  55. 49. 22. 26.  36 29 59 43  .68 .57 .83 .43  37 31 51 81  #  k= rumen d i g e s t a flow r a t e [%/hr]. l e t t e r s are s i g n i f i c a n t l y d i f f e r e n t  .33  45 44 54 16 10 16  28 60 20 21 03 33  .97 .65 .65 .92 .61 .78  36 84 1 1 36 63  30. 09 75. 84 35. 38 30. 97 33. 55 71 . 47  Values with d i f f e r e n t at (P<0.05).  relatively  low  fraction.  The  r a t e of CP net  significantly  degradation  result  f o r CP  (P<0.05) l o w e r  Bana g r a s s v a r i e t i e s rate  of d e g r a d a t i o n  maturity,  and  effective  DM  varieties  were low  was  s l i g h t l y higher  rate in  although  of CP  than  a significant  was  'b'  therefore a  degradability.  m o d e r a t e DM  s o l u b i l i t y 'a'  tended  CP  (P<0.05) e f f e c t  s o l u b i l i t i e s of  the  r a t e of CP other  decreased  and  to d e c l i n e with  a significant  f o r the  degradability  smaller  CP  'c'. These  degradability.  a  degradation  effective  had  t h e r e f o r e had  and  bana  grass  degradation  'c'  napier v a r i e t i e s .  with maturity,  (P<0.05) r e d u c t i o n i n e f f e c t i v e  on  The  resulting CP  degradation. G r e e n m a i z e c h o p and DM  and  CP  values).  fodder  s o l u b i l i t i e s and  also  sorghum h a d degraded  These c o n t r i b u t e d p o s i t i v e l y  difference  (P<0.05) i n e f f e c t i v e  two  feedstuffs  CP)  d e c l i n e d with maturity  increase  and  the  to the  napier v a r i e t i e s . f o r both  significant between  these  Solubilities  maize and  be  high  ( h i g h 'c'  sorghum.  i n t h e p r o p o r t i o n o f p o l y s a c c h a r i d e s and the  (DM  and  An  insoluble  cause.  grasses.  Figure curves  rapidly  degradation  proteins with maturity could possibly Pasture  relatively  2 shows t h e  o b t a i n e d . The  variation  resulting  Except  typical  model from DM  f o r Pennisetum . .34  pasture  fitted and  CP  grass  e x p l a i n e d 94 degradation  s p e c i e s and  late  degradation and  88%  i n the  bloom  of  the  rumen.  rhodes  grass,  the other  Degradation constant  g r a s s e s h a d low s o l u b i l i t y  rates  'c' e i t h e r  decreased  w i t h m a t u r i t y . However,  relatively  high degradation  rate  other  grasses. For a l l pasture  the been  first  (P<0.05) e f f e c t i v e  potential  s p e c i e s had  for degradation  degradation grasses  ('b'  30 h o u r s t h e m a j o r d i f f e r e n c e s  significantly  relatively  'c' c o n s t a n t s and  higher  appreciable  or remained  the Pennisetum  significantly pasture  (<14%).  than the  t h e r e was an  fraction).  Within  i n disappearance  had  (P<0.05) e s t a b l i s h e d .  Legumes. Figure  3 shows t y p i c a l  o b t a i n e d . The e q u a t i o n s the  variation  i n DM  legume d e g r a d a t i o n  fitted  curves  e x p l a i n e d 91.6 and 88.4% o f  and CP d e g r a d e d  i n t h e rumen  respect i v e l y . DM for rate  and CP s o l u b i l i t y  desmodium w h i c h was  'a' were q u i t e h i g h  less  than  (>18%)  14%. A l s o t h e d e g r a d a t i o n  c o n s t a n t s were h i g h a v e r a g i n g  0.06 a n d 0.08  CP r e s p e c t i v e l y .  The p r o p o r t i o n o f p o t e n t i a l l y  'b'  lower  fraction  was  shows t h a t CP formed material  after  incubation  f o r DM  the major d i f f e r e n c e s  DM  f o r DM a n d  degradable  f o r t h e CP. P o s s i b l y , t h i s  the g r e a t e r p r o p o r t i o n of the i n s o l u b l e  "established significantly  effective  than  one h o u r o f i n c u b a t i o n . W i t h i n  A significant  except  36 H o u r s  in degradation  post-  h a d been  (P<0.05).  (P<0.05) d e c l i n e o c c u r r e d  and CP d e g r a d e d . .35  between t h e  as l u c e r n e m a t u r e d . L u c e r n e  had  36.  Fig 3: % Degradation  Versus Incubation Time. Lucerne (LB).  100  -i  —  —  90 80 -\  10 ~\  oH  1  0  1  1  20 D  % DM Degraded.  1  40  1  1  60  Time Incubated in the Rumen [Hrs]. +• % CP Degraded.  37  1  l  80  F i g 4:% Degradation Versus Incubation Time. Rhubarb Leaves.  100 -i  •  10 H o H 0  1  1  1  20 •  % DM Degraded.  1—  40  1  1  60  Time Incubated in the Rumen [Hrs]. +• % CP Degraded.  3G  1  1  80  high  (>60%) e f f e c t i v e CP d e g r a d a t i o n . Desmodium was  relatively Crop  i n s o l u b l e and  both  undegradable.  residues. F i g u r e 4 shows t y p i c a l c r o p r e s i d u e s d e g r a d a t i o n curves  o b t a i n e d . The models f i t t e d e x p l a i n e d 90.7 variation  i n the DM and CP degraded  and 89.8%  of the  i n the rumen  r e s p e c t i v e l y . At the end of 36-42 hours of i n c u b a t i o n , the major disappearances had a l r e a d y been s i g n i f i c a n t l y (P<0.05) established. Crude p r o t e i n and dry matter  i n rhubarb l e a v e s , banana  l e a v e s , wheat straw and sweet potato v i n e s were h i g h l y s o l u b l e . Except f o r wheat straw, the o t h e r s have h i g h CP c o n t e n t . Rhubarb l e a v e s and wheat straw p r o t e i n  i s both  h i g h l y s o l u b l e and d e g r a d a b l e . However, the CP content of wheat straw was q u i t e low p r o p o r t i o n of the DM was  (5.7%) and the  predominant  n e i t h e r s o l u b l e nor d e g r a d a b l e .  Hence, the e f f e c t i v e DM d e g r a d a b i l i t y of Wheat straw significantly  (P<0.05) lower than f o r rhubarb  was  leaves.  Although rhubarb l e a v e s were h i g h l y s o l u b l e , the d e g r a d a t i o n rate  'c' f o r both i t s DM  and CP remained q u i t e h i g h . T h i s  r e s u l t e d i n high e f f e c t i v e  degradabi1 i t i e s  l e a v e s . D i f f e r e n c e i n disappearance due  f o r the  rhubarb  to the s m a l l p a r t i c l e  s i z e are s i g n i f i c a n t l y e s t a b l i s h e d d u r i n g the f i r s t i n - s i t u exposure  (Weakley  et a l . , 1983). T h i s was  hour of  also  observed with the rhubarb l e a v e s . Banana l e a v e s were marked by low DM  and CP d e g r a d a t i o n r a t e s . .39  'c' and a s m a l l  potentially  degradable  degradation  f o r banana l e a v e s was  of  the s o l u b l e The  fraction  CP s o l u b i l i t y  quite  similar.  about  two t i m e s  This  shows  that  was  than  t h e DM  similar  s t o v e r . The r e s u l t s  degradable  of wheat b r a n  components i n wheat  then  that  was straw.  lower  wheat  f o r wheat  relative  CP d e g r a d a t i o n r a t e  fractions  ' c ' f o r wheat  of e i t h e r  bran  straw and bran  straw or  were a s i g n i f i c a n t l y  DM d e g r a d a b i l i t y  bran.  higher Though  t o maize s t o v e r ,  'c' and  potentially  'b' were l o w . T h i s t h e r e f o r e r e s u l t e d i n (P<0.05) e f f e c t i v e  s t o v e r . From t h i s  good s o u r c e  low.  and m a i z e s t o v e r were  solubility  had a h i g h CP c o n t e n t  significantly  the r e s u l t  f o r m a i z e s t o v e r o r wheat  three times  t h e CP s o l u b i l i t y ,  maize  t h e r e f o r e mainly  s t o v e r . The DM d e g r a d a t i o n c o n s t a n t  bran  a n d CP  t h e p o l y s a c c h a r i d e components o f Wheat  (P<0.05) e f f e c t i v e wheat  DM  'a', and hence remained q u i t e  h i g h e r than  approximately  maize  *b'. E f f e c t i v e  o f wheat b r a n  However  were more s o l u b l e maize  fraction  trial  of d e g r a d a b l e  .40  CP d e g r a d a b i l i t y f o r  wheat b r a n  carbohydrates.  i s shown  t o be a  DISCUSSION  The by  total  degradability  (a+b). T h i s  dissolved  represents  of a feed  t h e amount o f p r o t e i n  and d e g r a d e d w i t h i n  t i m e . The sum undegradable  (a+b) c a n n o t  t h e rumen g i v e n  therefore  the  t h e amount  value  rate  passage  i s given  which  sufficient  100%. The  by  'P', and  i s a c t u a l l y degraded i n  r a t e . Hence t h e l o w e r t h e  o f t h e rumen d i g e s t a ,  canna, P a k i s t a n i  solubilities  low  degradation  the  significantly  the g r e a t e r  will  rates  (1980) a n d S e t a l a  hybrid  and b a n a n a  leaves  b u t low e f f e c t i v e d e g r a d a b i l i t i e s . 'c' could  be t h e  have p l a y e d  (1983),  observed  t h i s shows t h a t  relatively  green maize chop,  fodder  sweet p o t a t o v i n e s , degradability insoluble  significantly  protein  role in  rates  sorghum, k i k u y u g r a s s ,  solubility  could  solubility  d e g r a d a b i l i t y . For  high degradation  more a c c u r a t e l y .  protein  Their  by Mahadevan e t a l .  n o t be a good measure o f t h e p r o t e i n  feedstuffs•with  a major  had  (P<0.05) low e f f e c t i v e d e g r a d a b i l i t i e s  (<40%) r e a l i z e d . As was a l s o  may  w h i c h c a n be  o f 'P'. Edible  high  of a f e e d  rumen a t a s p e c i f i c  turnover  exceed  i s given  f r a c t i o n i n t h e rumen w o u l d be r e p r e s e n t e d by  l00-(a+b). E f f e c t i v e d e g r a d a b i l i t y represents  i n t h e rumen  ' c ' , e.g  lucerne  be r e l a t e d t o rumen  Hence, t h e p r o p o r t i o n  and i t s rumen d e g r a d a t i o n  i n f l u e n c e the e f f e c t i v e and/or . .41  of  rate e x t e n t of  and  degradation. The  d e c l i n e i n s o l u b i l i t y and e f f e c t i v e  degradability  with m a t u r i t y of legumes, fodder and pasture grasses c o u l d be a t t r i b u t e d to the g r a d u a l dominance of stem t i s s u e over t i s s u e and an i n c r e a s e i n l i g n i f i e d polysaccharides  leaf  structural  (Llano and De P e t e r s , 1985). With m a t u r i t y ,  there were i n c r e a s e s i n both ADF f e e d s t u f f s sampled  and NDF  content of the  (Table 2). A negative r e l a t i o n s h i p between  the degree of l i g n i f i c a t i o n and c e l l w a l l d i g e s t i o n i s w e l l recognized (Van Soest,  i n forages  1982). The d e c l i n e i n the  grass CP s o l u b i l i t y concurs with the o b s e r v a t i o n s made by Clark  (1975). The  slight  i n c r e a s e i n CP s o l u b i l i t y  with age while e f f e c t i v e CP d e g r a d a t i o n decreased, reliable  again p o i n t out the inadequacy  of l u c e r n e  significantly of s o l u b i l i t y as a  i n d i c a t o r of rumen d e g r a d a t i o n even w i t h i n s i m i l a r  feeds. C l a r k (1975) a l s o noted  that the s o l u b l e n i t r o g e n  content of forages i s g r e a t e s t at m a t u r i t y except  for cereal  grains. Wheat bran had a low CP s o l u b i l i t y and d e g r a d a t i o n though i t s CP content was significantly  (P<0.05) higher DM  energy  and a d d i t i o n a l  high ( 1 6 % ) . I t s  s o l u b i l i t y and  d e g r a d a b i l i t y show t h a t wheat bran degradable  effective  effective  i s a good source of rumen  intestinal protein  Wheat bran "contains i n s o l u b l e p r o t e i n s e.g g l i a d i n , and other residue p r o t e i n s ( I n g l e t t , and  1974). The  e f f e c t i v e d e g r a d a b i l i t y of wheat bran was . .42  supply. glutelin  solubility  observed  to be  quite  low { T a b l e  (1973) who a l s o glutelins and  4 and 6 ) . T h i s reported  low s o l u b i l i t y  a s major p r o t e i n  protein  including  agrees with with  f o u r main  g l o b u l i n s , prolamins,  soluble  i n ruminal  and  prolamins are higher  contain  disulfide  ruminal  fluid  solubility  be p r o v i d e d  o f wheat b r a n  amino a c i d s  absorption  t o wheat b r a n , m a i z e  f o r wheat  a s a good  that  contain  i n the  have a low extensive  by t h e d i s u l f i d e  abomasal  f r o m Wheat  To  digestion bran  depressed  protein  level  rumen b a c t e r i a , even  (less  i s below  though . .43  endorse  t h e CP c o n t e n t  straw. Voluntary than  feed  supplemented  this  protein.  Such  and o t h e r intake  8%) c o n t e n t  the nitrogen  straw  and e f f e c t i v e  o f rumen d e g r a d a b l e  due t o t h e low CP  1982). T h i s  a n d wheat  CP s o l u b i l i t y  to consider  f a c t o r s o f wheat  stover  s t r a w may e r r o n e o u s l y  source  a move however ought  Soest,  that  t o be i n v e s t i g a t e d .  degradability  be  proteins  r e s i s t a n t to degradation.  were low i n CP. The a p p r e c i a b l e  related  weight  and t h a t  relatively  the u t i l i z a t i o n  In c o n t r a s t  feedstuff  that  are l e s s a c c e s s i b l e to the p r o t e o l y t i c  enzymes a n d a r e a l s o  would have  fluid,  such as would  intestinal  proteins  b o n d s , w h i c h make them l e s s s o l u b l e  bonds o f g l u t e l i n s ,  and  weight  (Wohlt e t a l . , 1973). G l u t e l i n s  molecular  i n the ruminal  grains  t y p e s of p r o t e i n s  ( C l a r k e t a l . , 1987). P r o t e i n s  cross-linking,  determine  fluid  Cereal  and g l u t e l i n s .  A l b u m i n s a n d g l o b u l i n s a r e low m o l e c u l a r are  et a l .  p r o l a m i n s and  f r a c t i o n s i n feeds.  supplements c o n t a i n  albumin,  Wohlt  would (Van  requirement of  by r e c y c l i n g o f  urea. The  result  i s a depression  in d i g e s t i b i l i t y associated  with n i t r o g e n d e f i c i e n c y i n the rumen. T h e r e f o r e , both maize s t o v e r and wheat straw would be complete  inadequate  i f s u p p l i e d as  feeds.  In view of i t s high CP  s o l u b i l i t y and d e g r a d a b i l i t y , the  s o l u b l e p r o t e i n i n banana l e a v e s i s l i k e l y  to be comprised of  albumins and g l o b u l i n s . These p r o t e i n s are more degradable the rumen than are prolamins 1973). The utilised  and  glutelins  in  (Wohlt et a l . ,  p o s s i b i l i t y of banana l e a v e s p r o t e i n being  fully  by rumen microbes i s q u i t e h i g h .  With t h e i r high s o l u b i l i t y rhubarb leaves and  sweet potato  and  effective degradability  v i n e s are  promising  f e e d s t u f f s i n d a i r y p r o d u c t i o n . Rhubarb l e a v e s are high i n o x a l a t e s , but  the predominant carbohydrate  fermenters  rumen are unable to degrade o x a l a t e s . Feeding l e a v e s would be expected anaerobic  of  of  rhubarb  to i n c r e a s e the p r o p o r t i o n s of  oxalate-degrading  b a c t e r i a (Hobson and  fermenters.  Hobson and Wallace  the  Wallace,  1982), thus e n a b l i n g them to compete s u c c e s s f u l l y with carbohydrate  the  the  (1982), i n d i c a t e d  that on f e e d i n g o x a l a t e - r i c h feeds, the c a p a c i t y of the rumen fluid  to d e t o x i f y o x a l a t e would i n c r e a s e with time so that  otherwise then,  l e t h a l doses of o x a l a t e may  be d i g e s t e d . In essence  t h i s would mean that f e e d i n g rhubarb l e a v e s would only  be l i m i t e d by other n u t r i t i o n a l  requirements  and  not  by  o x a l a t e t o x i c i t y . The  high s o l u b i l i t y and d e g r a d a b i l i t y of  in rhubarb l e a v e s and  sweet p o t a t o v i n e s c o u l d be a s s o c i a t e d .  .44  CP  with the h i g h d e g r a d a b i l i t y of albumins and  g l o b u l i n s . This  i s unfortunate  in that albumins and  b e t t e r balance  of amino a c i d s and a h i g h e r b i o l o g i c a l  than do prolamins  and  glutelins  l e a v e s have high CP content  g l o b u l i n s normally  have a value  ( C l a r k et a l . , 1987). Banana  (15%)  and  were h i g h l y  undegradable. More i n f o r m a t i o n on the amino a c i d content their a v a i l a b i l i t y  i n the small i n t e s t i n e s would be needed  before e s t a b l i s h i n g the amount of milk p r o d u c t i o n supported  by  and  that can  feeding banana l e a v e s to cows. S a t t e r (1983)  observed s i m i l a r c o n s i d e r a t i o n s in f o r m u l a t i n g d i e t s on b a s i s of p r o t e i n  degradation.  .45  the  be  SUMMARY AND  CONCLUSIONS  The r a t e c o n s t a n t s and e f f e c t i v e d e g r a d a t i o n  i n the  rumen f o r the v a r i o u s f e e d s t u f f s are given i n the preceeding Tables. Green maize chop, fodder sorghum, clone.13  v a r i e t y had moderate to h i g h l y degradable  (50-60%). Together these  bana grass and  with kikuyu grass and  fodder grasses may  DM and CP  trachyphyllum,  have adequate p r o t e i n  medium y i e l d i n g d a i r y cow. However n i t r o g e n  supplies for a  supplementation  would be r e q u i r e d as the g r a s s e s mature. Energy s u p p l i e s would have to be e v a l u a t e d . For the other g r a s s e s DM and CP degradation were s i g n i f i c a n t l y at an e a r l y stage of growth. Lucerne, rhubarb  effective  (P<0.05) lower  even  sweet p o t a t o v i n e s and  l e a v e s c o u l d p r o v i d e the supplemental  nitrogen during  p e r i o d s of d e f i c i e n c y . In view of t h e i r  low rumen d e g r a d a b i l i t y , banana  leaves  and desmodium and/or wheat bran c o u l d supplement some of the energy  and p r o t e i n needs when e i t h e r maize s t o v e r or Wheat  straw are f e d . Banana  leaves and desmodium may  not support  high milk p r o d u c t i o n . A t t e n t i o n must be given to t h e i r a c i d content, a v a i l a b i l i t y  amino  of the undegraded p r o t e i n and the  "protein s t a t u s of the l a c t a t i n g cows. Rhubarb leaves have a h i g h rumen CP and DM and, low ADF and NDF  degradability  contents. A possible ration could . .46  include molasses, sugars then  and  be  also  used  both  to  as  a source  readily  improve p a l a t a b i l i t y .  to supply  the  fermentable  Maize stover c o u l d  fibre.  Rhodes g r a s s , r e d o a t s supplemented  of  g r a s s and  s t a r g r a s s need t o  with m a t e r i a l s of h i g h bypass p r o t e i n  bulk. This w i l l  enable  g r a s s e s . Wheat b r a n  microbial utilization  would  be  a suitable  of  and  be low  these  feedstuff  for  this  purpose. Sweet p o t a t o both  fermentable Maize  wheat be  by  milk  straw  used  protein  s t o v e r and  utilization Although  v i n e s and  as  their  lucerne could usefully  and  wheat low  CP  energy straw  fed to d a i r y  a source  of  fibre.  Green maize chop,  fodder  grass,  P.  trachyphyllum,  potato  v i n e s , l u c e r n e and  d e g r a d a b i l i t y . These potential The  be  limited and  low  the  low  feedstuffs. in  DM  degradation.  when m a i z e  cattle,  these  their  stover  feedstuffs  sorghum, n a p i e r g r a s s ,  rhubarb  l e a v e s , banana  desmodium had  feedstuffs  and could  kikuyu  l e a v e s , sweet  moderate to  therefore offer  a  high  great  for conservation. p r o p o r t i o n of  degradation  r a t e has  insoluble  significant  degradation.  Hence s o l u b i l i t y  indicator  protein  The  are  contents  production w i l l  are  across  supplement  of  of  and  i t s rumen  i n f l u e n c e on  alone  may  not  the  be  a  effective good  degradability.  d e c l i n e i n DM  with maturity  protein  solubility  f o r a g e s c o u l d be . .47  and  effective  attributed  degradability  to the  gradual  dominance of the stem t i s s u e over increase  i n the l i g n i f i e d  structural  P r o t e i n s that have a low and  the l e a f  t i s s u e and  an  polysaccharides.  solubility  that c o n t a i n e x t e n s i v e c r o s s - l i n k i n g ,  i n the ruminal  fluid  such as would be  p r o v i d e d by the d i s u l f i d e bonds of g l u t e l i n s e.g  i n Wheat  bran, are l e s s a c c e s s i b l e to the m i c r o b i a l p r o t e o l y t i c enzymes and  relatively  r e s i s t a n t to  To o b t a i n optimum p r o d u c t i o n to be adequate i n t a k e . Intake d e g r a d a b i l i t y . Low by e x c e s s i v e l i g n i n  and  i n a d a i r y cow,  can be hampered by  there low  slow d e g r a d a b i l i t y which may  l e v e l s or n u t r i t i o n a l  reduces f i b r e d i g e s t i o n and contents  degradation.  below 8% as was  results  has  rumen be caused  deficiencies  in poorer  i n t a k e s . CP  o b t a i n e d with Maize s t o v e r , Wheat  straw or the mature pasture  grasses would be  inadequate  for  maximum d a i r y p r o d u c t i o n . However, d u r i n g the dry season when d a i r y feeds are i n short supply, a combination quality  roughages with p r o t e i n and  be used. T h i s combination high milk  production.  .48  of the  low  energy supplements c o u l d  would not be expected  to s u s t a i n  CHAPTER  2.  THE EFFECTS OF FORAGE PARTICLE LENGTH AND PROTEIN SOURCES ON INTAKE, MILK YIELD AND RATION DIGESTIBILITY BY DAIRY CATTLE.  HEAT TREATMENT OF COMPOSITION AND  INTRODUCTION With the onset of l a c t a t i o n a r a p i d increase requirement a r i s e s which cannot be met  in p r o t e i n  by m i c r o b i a l  protein  a l o n e . Feeding h i g h l y degradable p r o t e i n s would supply i n s u f f i c i e n t amounts of amino a c i d s to the  i n t e s t i n e s over  t h i s p e r i o d . Responses to a d d i t i o n a l undegradable p r o t e i n terms of  increased  milk y i e l d , milk f a t and  been noted in l a c t a t i o n  a l t e r i n g m i c r o b i a l a c t i v i t y and factors involved  rumen, feed crosslinking  intake,  ruminal d e g r a d a t i o n access to feed  include  protein  moderate s u p p l i e s  i s also considered  The  the  storage are  been looked upon  of energy and  protein.  The  to be a good source of undegraded solubility  r a t e of d e g r a d a t i o n of p r o t e i n  treatment of good q u a l i t y p r o t e i n s  dehydrated-alfalfa  some  source, while dehydrated  p r o t e i n . Heat treatment decreases both the p r o t e i n and  of  supplements f o r d a i r y cows in Canada and  as a r e a d i l y degradable p r o t e i n  latter  and  the  dehydrated a l f a l f a  i n the P a c i f i c Northwest. Canola has  a l f a l f a has  components.  the extent  processing  e f f e c t s on p r o t e i n . Canola meal and  states  by  r e t e n t i o n time in  solubility,  i n the p r o t e i n , and  used as p r o t e i n  milk p r o t e i n have  trials.  Numerous f a c t o r s i n f l u e n c e  Among the  in  meal should allow . .49  i n the  such as canola  adequate n i t r o g e n  of rumen. or to  become a v a i l a b l e f o r maximum rumen m i c r o b i a l growth. I t should a l s o allow s i g n i f i c a n t amounts of the d i e t a r y to  protein  bypass ruminal d e g r a d a t i o n . O v e r a l l , the e f f i c i e n c y of  utilization  by the animal  should be improved.  P h y s i c a l f a c t o r s a s s o c i a t e d with p a r t i c l e p a r t i c l e s p e c i f i c g r a v i t y a f f e c t passage from  s i z e and the rumen.  I n i t i a l m a s t i c a t i o n , m i c r o b i a l fermentation and rumination play a s i g n i f i c a n t  r o l e i n roughage i n g e s t a communition.  Small p a r t i c l e s have g r e a t e r s u r f a c e area a c c e s s i b l e to m i c r o b i a l a t t a c k and thereby  increase d i g e s t i o n  r a t e . Hence  forage p a r t i c l e s i z e w i l l have an e f f e c t on the r a t e at which m a t e r i a l w i l l pass through of  the rumen as w e l l as on the extent  d i g e s t i o n o c c u r r i n g w i t h i n the rumen. By r e d u c i n g the  p a r t i c l e s i z e of forage the amount of chewing r e q u i r e d per u n i t of feed i s reduced. M i l k f a t content has a l s o been to  be reduced.  I t i s expected  then t h a t t h i s reduced  means that m a t e r i a l should be passing through l e s s requirement  from  chewing  the rumen with  f o r p h y s i c a l breakdown. Supposedly  p r o t e i n w i l l accompany t h i s dry matter  found  more  the rumen. T h i s  t r i a l had two o b j e c t i v e s ; a) To determine  the e f f e c t of forage p a r t i c l e  feed i n t a k e , milk y i e l d and c o m p o s i t i o n ,  l e n g t h on  and r a t i o n  digestibility. b) To determine  the e f f e c t of heat  treatment  of two  p r o t e i n sources on feed i n t a k e , milk y i e l d and composition, and r a t i o n . .50  digestibility.  LITERATURE REVIEW  PROTEIN AND  ENERGY FOR  LACTATING DAIRY COWS.  Output from a given on  energy supply; and  required supply  l e v e l of p r o t e i n  v i c e versa,  intake  the amount of  i s dependent protein  to s u s t a i n a p a r t i c u l a r output depends on  (Broster  researchers  and  Oldham, 1981). Further  the  energy  two  have quoted some work which confirmed  that  energy intake does i n f l u e n c e the milk output supported by a given  amount of p r o t e i n . I n c r e a s i n g  greater  energy supply had  a  e f f e c t on milk y i e l d than i n c r e a s i n g p r o t e i n . Paquay  et a l . (1973) have e s t i m a t e d the optimal d i e t a r y r a t i o s of m e t a b o l i z a b l e energy to p r o t e i n . Too  wide a r a t i o  milk y i e l d , while a narrow r a t i o i s not a d d i t i o n these r e s e a r c h e r s  With the onset of l a c t a t i o n an  (Orskov et a l . , 1981; 1983). T h i s  insufficient incorporation  to meet the net  production.  by m i c r o b i a l  Mahadevan et  synthesis  net  is  amino a c i d requirement for  i n t o milk p r o t e i n . There are very few  which i n c r e a s e s  protein  so because the y i e l d of  from m i c r o b i a l p r o t e i n  of  in p r o t e i n  E r f l e et a l . , 1983;  i s thought to be  amino a c i d n i t r o g e n  l e v e l of  increase  requirement a r i s e s which cannot be met  al.,  b e n e f i c i a l . In  observed that the optimal r a t i o  p r o t e i n to energy f e l l w i t h i n c r e a s i n g  alone  reduces  data in  in milk y i e l d have been o b t a i n e d from  a source of p r o t e i n with a low . .51  feeding  d e g r a d a b i l i t y to cows in  energy balance or i n m a r g i n a l l y p o s i t i v e energy (Clark, produced  1975;  balance  B r o d e r i c k , 1975). Since the m i c r o b i a l  protein  i s c o n s i d e r e d to be r e l a t i v e l y c o n s t a n t per u n i t of  m e t a b o l i z a b l e energy  (ME)  (ARC,  1980;  Orskov  there i s , t h e o r e t i c a l l y , a requirement p r o t e i n as milk y i e l d  et a l . ,  for a less  i n c r e a s e s . Experiments  1981),  degradable  conducted  to  t e s t t h i s h y p o t h e s i s , u s i n g p r a c t i c a l milk p r o d u c t i o n t r i a l s , have o f t e n  f a i l e d to r e v e a l any d e t e c t a b l e change i n milk  y i e l d when p r o t e i n s expected to have d i f f e r e n t have been used 1981;  (Kaufmann and Lupping,  C l a y and S a t t e r ,  1979).  1982;  degradability  Orskov  et a l • ,  I f the cows are consuming ME i n  excess of t h e i r requirement, then more m i c r o b i a l p r o t e i n be a v a i l a b l e . T h i s may protein  will  o c c a s i o n a l l y mask responses to d i e t a r y  (Kaufmann and Lupping,  1982). Orskov  et a l • (1981)  however noted t h a t , what i s probably more important the r a t e of outflow of p r o t e i n  i s that  from the rumen i n c r e a s e s as  the food i n t a k e i n c r e a s e s . Even though comparatively  intake has been r e c o g n i z e d as a  independent  ordinary ration  n u t r i t i o n a l a t t r i b u t e , most  f o r m u l a t i o n programmes assume that a d i e t of  higher net energy  (NE) or d i g e s t i b i l i t y w i l l  be consumed i n  g r e a t e r amounts (Van Soest et a l . , 1984). Hence, i f the cows eat to t h e i r ME  requirement,  i n c r e a s i n g milk y i e l d . An  then i n t a k e i n c r e a s e s with  i n c r e a s e i n the f r a c t i o n a l  rate can thus make a s u b s t a n t i a l d i f f e r e n c e to the d e g r a d a b i l i t y of the p r o t e i n . Orskov . .52  outflow  effective  et a l . (1981 ) termed  t h i s as a self-compensating mechanism whereby an i n t a k e leads to a lower d e g r a d a b i l i t y . Evidence  increase in exists  i n d i c a t i n g that the e f f e c t i v e y i e l d of m i c r o b i a l p r o t e i n i n c r e a s e s with outflow  rate.  Cows i n e a r l y p a r t of l a c t a t i o n but, i n negative balance  respond  by  i n c r e a s i n g t h e i r y i e l d of milk when they  are given undegradable  protein  supplements (Orskov  1981). P r e v i o u s l y Orskov et a l . (1977) had in an experiment o f f e r e d ME The  energy  et a l . ,  illustrated  this  i n which p o t e n t i a l l y h i g h - y i e l d i n g cows were  to support o n l y 10 Kg of f a t c o r r e c t e d milk  (FCM).  cows were then given e i t h e r c a s e i n or g l u c o s e ,  abomasally.  The  cows given c a s e i n i n c r e a s e d t h e i r milk f a t  and p r o t e i n content, and a l s o the milk y i e l d . Only when cows were r e s t r i c t e d  i n i n t a k e during e a r l y l a c t a t i o n , or given a  d i e t which d i d not enable d i d the animals  respond  them to meet t h e i r p r o t e i n need,  to supplements of p r o t e c t e d p r o t e i n  (Cressman et a l . , 1977;  R o f f l e r et a l . , 1978). I t would  appear that p r o t e i n s t i m u l a t e s milk y i e l d and i n c r e a s e s weight l o s s i n e a r l y response al.,  i s not seen  thereby  l a c t a t i o n , but a  i n mid and  late lactation  similar (Orskov et  1 981 ). Both the l e v e l of energy  p r o t e i n content of m i l k . The percent p r o t e i n content  and p r o t e i n  i n the d i e t  affect  l a t t e r does so o n l y up to 18  i n the concentrate but not beyond  ( B r o s t e r and Oldham, 1981). Increases occur  i n a l l the major  milk p r o t e i n s , namely; c a s e i n , £>-lactoglobulin and  . .53  D-  lactoalbumin around  normal  content extra  ( B r o d e r i c k , 1975). G e n e r a l l y p r o t e i n levels  of milk,  dietary  therefore rather  feeds  effect  on  B r o s t e r and  Oldham  indicated  protein  i n c r e a s e t h e NPN  may  q u i t e apparent  than  content.  but  have l i t t l e  protein  supply  Energy w i l l  and  that  which  limit  forages are  in practice  milk  used.  and  f o r a g e s a r e of Other  respond  23  kg  infusion.  per  ammonia, improving Lupping,  milk The  use  poor q u a l i t y  where l i t t l e (Van  protein yield  (Orskov,  protein  i f less  digestible for pastures,  Casein  with  intravenous  It also  stress  c o n d i t i o n s f o r good 1982). O r s k o v in protein  negative  (1982)  on  decreases  liver  (Kaufmann  indicates  that  balance  from  the  methionine the  amino  surplus hence  and response  d e p e n d v e r y much on  i n the  16  obtained  m e t a b o l i s m and  fertility  degradability  energy  the  will  infused  (1972) a l s o  of p r o t e c t e d p r o t e i n s i m p r o v e s  reducing  cows  f a t c o r r e c t e d milk  1982). F i s h e r  secretion  i s fed,  e t a l . , 1984).  infusions. of  supply  protein  concentrate  Soest  any  It i s  i t i s energy  have shown t h a t l a c t a t i n g  to the a n i m a l .  thus  differences of  day  on  that  in milk.  T h i s problem e x i s t s  quality  i n c r e a s e d the  supply  extent  low  to post-ruminal  improved  acid  tropics  experiments  abomasally to  i n the  protein  influences milk protein  unsupplemented g r a z i n g animals particularly  the  intakes  to the  cow.  FORAGE DIGESTION. Formulation should  be  based  of h i g h on  forage d i e t s  accurate . . 54  estimates  for high-producing of d i g e s t i b i l i t y  of  cows the  d i e t as a f f e c t e d by i n t a k e , c o s t and amount of c o n c e n t r a t e s . Maximum u t i l i z a t i o n fermentation  of forages by ruminants depend on a c t i v e  i n the rumen. Negative  a s s o c i a t i v e e f f e c t s have  been r e c o g n i z e d under v a r y i n g supplementation (Llano and De P e t e r s , digestibility  programmes  1985; Hunt, 1985). I t occurs when  of a feed mixture  i s l e s s than  t h a t of the sum  of the i n d i v i d u a l components ( M i l l e r and M u n t i f e r i n g , 1985). The  magnitude of any a s s o c i a t i v e e f f e c t s vary with the  physical  form of the d i e t ,  r a t i o of forage t o c o n c e n t r a t e and  the q u a l i t y of f o r a g e s . P l a n t s produce compounds t h a t p r o v i d e among other t h i n g s , a degree of p r o t e c t i o n a g a i n s t m i c r o b i a l i n v a s i o n . Included  i n these p r o t e c t i v e compounds a r e l i g n i n , and the  phenyl-propanoids c u t i n and s i l i c a  a s s o c i a t e d with l i g n i n (Van Soest,  s t r u c t u r e , tannins,  1982; Jung and Fahey, 1983). The  c o n c e n t r a t i o n s and form of these compounds i n g r a i n s and g r a i n by-products,  as w e l l as forages, may be p a r t i a l l y  r e s p o n s i b l e f o r d i f f e r e n c e s i n f i b e r d i g e s t i o n among v a r i o u s feedstuffs. Age at which forages a r e h a r v e s t e d  i s r e l a t e d to t h e i r  n u t r i t i v e v a l u e . T h i s i s e x p l a i n e d by g r a d u a l dominances of stem t i s s u e over  leaf  t i s s u e and i n c r e a s e d  lignified  s t r u c t u r a l p o l y s a c c h a r i d e s a s s o c i a t e d with a g i n g De P e t e r s , 1985). A negative of 1 i g n i f i c a t i o n recognized  (Llano and  r e l a t i o n s h i p between the degree  and c e l l w a l l d i g e s t i o n i n forages  (Van Soest,  1982). In a d d i t i o n t o t h i s . .55  i s well limitation  on  fiber  of  the  or  their  d i g e s t i o n by  microbes,  phenylpropanoid  reduce  units,  complexes w i t h  ruminal  i t appears that  p-coumaric  h e m i c e l l u l o s e and  d i g e s t i o n (Hoover,  early  cut  given  Total Digestible Nutrients  compared and  hay  reduced  with  Fahey  late  the  decline in fiber  a s s o c i a t e d with  depressions  concentrations  in t a l l of  shown t o d e c r e a s e  De  and  fescue  p-coumaric in forages,  depress  Peters,  dry  and  relationship  and  lignin  contents  of  has  the  sum  of  component  lignin (Hoover,  Cutin Hoover 48  hour  content  l a g time  interaction  that  intact  in i n i t i a t i o n  no  intact.  either  single  and  Jones,  1968).  c o u l d cause a  s p e c i e s and  between c h e m i c a l . .56  shows t h e  6 to  plant genotype. I t  importance  components and  with  sources.  d i g e s t i o n took p l a c e as This  and  associated  of d i g e s t i o n of  plant  (Kumar  silica  with  cuticle  been  enzymes  between  v a r i e s m a r k e d l y among f i b e r  a l s o that  remained  Soest  with  acid.  have a l s o  been o b s e r v e d ,  more c l o s e l y than  Van  This varied with  reported  cuticle  silica  1986;  (1986) r e p o r t e d  particles. was  and  are  whereas  matter d i g e s t i o n  reciprocal  depressions  1985). J u n g  ferulic  inhibit  1984). A  a  as  lignin,  tannins  Singh,  digestibility  to a t t a i n  were a s s o c i a t e d  and  forages  quality  digestion in  increased  m i c r o b i a l metabolism,  cellulases  also  concentration  (1984) f o u n d  sorghum g r a i n s and  including  (TDN)  acids,  high  amount of g r a i n s needed  ( L l a n o and  was  ferulic  1986). U s i n g  hay  digestibility  In  the  presence  cellulose  cut  mature a l f a l f a  increased  and  the  l o n g as" "the of  physical  the  treatment  of  the  plant  on  Pond e t a l . (1984) f o u n d by  mastication  with  and  barriers be  t o be  cellwall  that  on  as  the  a  of  a major  by  material  factor associated  suggest  degradation  c u t i n and  chemical  that  effects  of  enzymes. T h e s e  These  factors (1986)  phenylpropanoids appear  responses could  a decrease  plant  through p h y s i c a l  silica.  microbial activity  l a g t i m e and  cuticular  l a g t i m e phenomenon. H o o v e r  depressing  inhibition  conducted  reduction.  including lignin,  indicated  b o t h as  size  alter  expressed  tannins  d i s r u p t i o n of  above mentioned o b s e r v a t i o n s  c o m p o n e n t s can  may  the  rumination  feed p a r t i c l e The  d i g e s t i o n . Studies  i n r a t e of  be  to  and  involve  expressed  cellwall  digestion. Forage p a r t i c l e Typically dairy  feeds.  size  and  forages  The vary  the  depend on  roughages, e f f e c t i v e and  However, t h e r e of  high  Amongst required  them  the only  maintain  proportion  of  forages  concept as  milk  a  has  source  fat  been of  of  Fisher  cereal grains fact  that  fiber  ( F o s t e r and  of  forages in  the  forages  are  to  stimulate  Woods, the  by  1970).  feeding  value  (1985) a t t r i b u t e d the t o a number o f f a c t o r s :  a higher  e x p l o i t a t i o n of . .57  that  of  to  fermentation  i s a growing a p p r e c i a t i o n of  i s the  i n the  largest proportion  active microbial  q u a l i t y forages.  supplementation  the  g r e a t l y . Maximum u t i l i z a t i o n  rumen. T r a d i t i o n a l l y ,  rumination  make up  relative  concentrates ruminant  digestion.  the  nutrient density  greater  is  genetic potential  of  the  d a i r y cow.  assumed  t o be  differences response Results  A l s o maximum m i l k  the  optimum  in forage  quality  of  a depression  in fiber  associated with  gravity  affect  acquires  nutrients  passage  the  forage-based  the  and  et  and  most  However factor from  no  factor  overall  change  - rumen e n v i r o n m e n t Other  results  plastic  ribbon  can,  the  from t h e 7-cm  cause  need  specific Particle  f o r rumen being  bypass  placed  important  factors  p r o t e i n metabolism  mastication, microbial play a  Moir,  i n the  role  process  i n roughage  been h y p o t h e s i z e d  1964)  that  of  i s the size.  the c o n t r i b u t i o n of  m a t u r i t i e s of  in nylon  same r e s e a r c h e r  long with . .58  (Kerley  reduction. Selected  s p e c i e s and  days  ingesta  rumination  r e d u c t i o n of p a r t i c l e  to determine  10  se,  1986).  a 0.90  bags  (Welch,  showed t h a t  specific  each  stems  hay  i n p h y s i c a l form when s u b j e c t e d  for  readily  per  particle  (Welch,  passage are  1 9 8 6 ) . I t has  several different  virtually  of  the  1986). A l s o p h y s i c a l  and  rumen  on  systems.  Initial  i t is difficult to the  diet  size  i n view  t i m e and  P e a r c e and  important  forage  the  rumination  (Welch,  a l • , 1985;  t h e a d d i t i o n of  intake, d i g e s t i b i l i t y ,  p r o t e i n escape.  communition  from  production  c o n t r o l of  fermentation,  to a  effect  supplementation.  i n c r e a s i n g economic p r e s s u r e  Rumen r e s i d e n c e in  that  been  Subtle  have an  to s p e c i f i c  particle  importance  and  and  d i g e s t i o n (Hoover,  factors  on  exist  some s t u d i e s s u g g e s t carbohydrates  has  of p r o d u c t i o n .  i n rumen d i g e s t i o n due  fermentable  size  level  production  showed to  the  1982)". lengths  gravity  of  required before  extensive  they  rumination  could  pass  from  Although p a r t i c l e s -omasal o r i f i c e ,  Welch  leaving  the  idea  a critical  et  of  i n the  cattle  small  (1967) f o u n d passed  digesta nm  for  quoted  size  from the  out  the  Small  the  pass  from  particles the  et  size  fiber  more t h a n by  600  used  to  700-  consuming  be  required that (1986)  to  that  the  i t difficult  action. area  a c c e s s i b l e to  increasing digestion  p a r t i c l e s i s that . .59  this  average  Welch  found  surface  a l . (1985) i n d i c a t e s t h a t  of  sheep a l l  sheep  thus making  orifice  sheep  Smith et a l .  mechanism  unclear.  I t was  of  a l . (1985) a l s o  o p t i c s was  4 mm,  have g r e a t e r thereby  most  source  seems t o  exact  the  Kerley  that  rumen o f  rumen o f  is s t i l l  Kerley  small  original  the  attack  ingesting  reported  Kerley  microbial et  e t a l . , 1980;  reticulorumen.  in c a t t l e .  separation  and  l e d to  approach approximately  rumen, but  orifice  particles  particles  T h i s has  l e a v i n g the  particles  maximum o p e n i n g was to explain  must  reticulo  gastrointestinal tract  screen.  some work where  photograph the  1 mm.  (Poppi  i s the  l i b i t u m . Small  passage  t h a t most  the  d i f f e r e n c e s among f o r a g e s ,  digesta w i l l  ad  separates has  mm  reduction  pass through  than  size  that p a r t i c l e s  particle  may  s i e v e . The  population  size  rumen.  a l . (1980) has  mm  that despite  before  forages  et  1.18  particle  (1986) n o t e d smaller  t h r o u g h a 0.84  reported  5 cm  post-ruminal  pass a  particle  the  particle  a l . , 1985). P o p p i  particles and  rumen a r e  of  and  the  the  greater  r a t e of  rate.  effect  passage  of from  the  rumen  i s increased.  Since  rumen d i g e s t i o n  result  of c o m p e t i t i o n  between d i g e s t i o n  factor  that  passage  increases  available  for microbial  decreases  rumen  Effect  chemical wall for  also decreases t o the d i g e s t a  among  forages,  grains  composition  can a l t e r  by rumen m i c r o b e s . T h i s  Mertens and L o f t e n  (1980) u s e d  to explain  when s t a r c h  to diets  were t h a t  the a d d i t i o n  of s t a r c h  However t h e y  i t u n l i k e l y that  would e x p l a i n  the depression  depression to t h e d i e t conditions Competition  that  of f i b e r  associated  with  fiber  dry  matter  digestibility  and  Muntifering  with  of c e l l u l o l y t i c starch  were a l s o a s s o c i a t e d  that  increased lag digestion.  in vivo. 1966), i t  starch  activity  addition by a c i d  fermentation.  with  when c o n c e n t r a t e s  (1985) o b s e r v e d . .60  Their  f o r the i n vivo  between p a s s a g e and d i g e s t i o n  digestible  digestibility  (Hungate,  associated  rapid  ruminants.  forage  digestion  t h e p r i m a r y mechanism  i s a reduction  by  e i t h e r o f t h e two e f f e c t s  in fiber  digestion  of c e l l  responsible  of f i b e r  c e l l u l a s e i s sensitive to a c i d i t y  was s u g g e s t e d  intake  f o r ruminants.  the p o t e n t i a l extent  found  be  in in vitro  time and d e c r e a s e d  Since  may  rates  the k i n e t i c s of  the decrease  i s added  observations  and, thus  and b y - p r o d u c t s i n  of v a r i a t i o n i n d i e t dry matter  digestion  the time  on d i g e s t i o n .  and a n a t o m i c a l  degradation part  attachment  and p a s s a g e , any  fermentation.  of c o n c e n t r a t e s  Differences  rates  i s the net  fiber  forpotentially the depression are fed.  of  Miller  digestibility  d e p r e s s i o n i s mediated p r i m a r i l y through decreased p o t e n t i a l extent of d i g e s t i o n ; l a g e f f e c t s and c o m p e t i t i o n between d i g e s t i o n and passage d i d not appear components of f i b e r  digestibility  to be  significant  d e p r e s s i o n when g r a i n i s  fed. Measurement of r a t i o n  digestibility.  Ration d i g e s t i b i l i t y  c o u l d be measured through the  conventional faecal c o l l e c t i o n  method. However markers (both  n a t u r a l and e x t e r n a l ) o f f e r some d i s t i n c t and Luckey  did  Kotb  (1972) reviewed the use of markers i n  digestibility advantages  advantages.  s t u d i e s . They concluded that markers o f f e r  of cheapness  not s p e c i f i c a l l y  the  and convenience. T h e i r review however  c o n s i d e r the use of A c i d - I n s o l u b l e  (AIA) as a d i g e s t i b i l i t y  Ash  marker.  Van Keulen and Young (1977) found the dry matter digestibility  c o e f f i c i e n t s e s t i m a t e d by the AIA marker method  to be very c l o s e to the c o e f f i c i e n t s determined by the traditional  total  faecal c o l l e c t i o n  method. Thonney et a l .  (1979) compared AIA and permanganate l i g n i n determine d i g e s t i b i l i t y did  of c a t t l e  as i n d i c a t o r s to  r a t i o n s and  not underestimate d i g e s t i b i l i t y  found that  determined by the  collection  method s i g n i f i c a n t l y  lignin  found to underestimate d i g e s t i b i l i t y  was  total  (P<0.001). Permanganate by 23.9%.  PROTEIN SUPPLEMENTATION. The most s u c c e s s f u l attempts at improving rumen fermentation has been with p r o t e i n .  .61  supplementation  AIA  (Hunt,  1985). L l a n o intake  and  depressed  depressions bacteria  are  dependent  Peters  digestibility  strictly  the on  and  amino a c i d s organisms  legumes. and  of  result  has  also  been  1966). Hence t h e  superior  improved  possibly  feeding  to other  (1986) has  cause  practices  rumen t u r n o v e r  include  organisms. High  ample  found  of  valine,  for  of  for  amylolytic  competition  between  nitrogen  limiting  an  NPN's i n quoted  available with  maintaining  some work where  ammonia medium o f  reduced  rumen  and  for lactating through high  s t a r c h and  organic  a  low  cattle feed  soluble  suppression  intake,  and  protein,  may  of  fermentable carbohydrates amylolytic  peptides. This . .62  which;  matter d i g e s t i o n . T h i s  e f f e c t s on  r a p i d g r o w t h of  amino a c i d s  (Orskov,  requirements. Supplementation  g r o w t h on  p r i m a r i l y through  encourage  such  bacteria.  rapid  which a l s o  occur  ammonia  d i g e s t i o n . Hoover  encourage  deamination  n o n - f i b r o l y t i c organisms  w o u l d be  Current  acids  for  peptides  affect  cellulolytic  fatty  is also  or  compounds under c o n d i t i o n s  amino a c i d s  rate  requirement  containing  fiber  require  2-methylbutyrate  and  proteins  lower  i s o l e u c i n e r e s p e c t i v e l y . A high  (Hungate,  may  them  branched-chain  f r o m the  high  Cellulolytic  growth  fibrolytic  protein  although  forages,  most o f  i s o v a l e r a t e and  1982). These p r o d u c t s and  with  source. Their  presence  that  for various  anaerobic  nitrogen  the  isobutyrate  leucine  (1985) o b s e r v e d  were a s s o c i a t e d  ammonia a s  as  De  microbes  in turn  would  would  fibrolytic  would  that limit  require  a v a i l a b i l i t y of amino a c i d s and ammonia n i t r o g e n r e q u i r e d f o r f i b r o l y t i c microbes. Under these c o n d i t i o n s , ammonia requirements may  exceed 3-8  1982), and there may  mg  percent (Kaufmann and Lupping,  be a h i g h e r requirement  f o r amino or  isoacids. Canola meal and dehydrated a l f a l f a as p r o t e i n  supplements.  Canola meal d e r i v e d from the c r u s h of c a n o l a seed, i s used as a p r o t e i n supplement  for livestock  s t a t e s of the P a c i f i c Northwest. of rapeseed, which was 1936  first  for i t s o i l ( B e l l ,  i n Canada and some  Canola i s a g e n e t i c  cultivar  i n t r o d u c e d i n t o Canada around  1984). Rapeseed i s h i g h i n e r u c i c  a c i d and g l u c o s i n o l a t e s , and f e e d i n g h i g h l e v e l s of the meal to monogastric animals reduced d i e t p a l a t a b i l i t y and animal performance  (De P e t e r s and Bath,  used as the s o l e p r o t e i n  1985). Canola meal c o u l d be  source i n the d i e t  of l a c t a t i n g cows  without adverse e f f e c t s on feed i n t a k e , m i l k y i e l d or composition  (Bell,  1984).  The g l u c o s i n o l a t e s or more s p e c i f i c a l l y p r o d u c t s , have g o i t r e - p r o d u c i n g p r o p e r t i e s Sanchez and C l a y p o o l ,  their  (Bell,  1983). More pronounced  hydrolytic 1984;  glucosinolate  breakdown and g r e a t e r g o i t r o g e n i c i t y seems to r e s u l t a d d i t i o n of myrosinase  to the d i e t  (Bell,  from the  1984). T h y r o i d  f u n c t i o n i n l a c t a t i n g cows, i n response to rapeseed meal f e e d i n g , has been assessed by the a d m i n i s t r a t i o n of t h y r o t r o p i n r e l e a s i n g hormone (TRH)  and t h y r o i d  stimulating  hormone (TSH). The h i g h g l u c o s i n o l a t e rapeseed meal (HG-RSM) . .63  caused  i n c r e s e d TSH  l e v e l s , whereas low  rapeseed meal (LG-RSM) r e s u l t e d (Bell,  glucosinolate  i n no change from the  normal  1984). B e l l a l s o found i n c r e a s e d t h i o c y n a t e l e v e l s i n  m i l k and By  reduced 1981,  iodine levels  two  "double  low"  i n blood and m i l k . rapeseed c u l t i v a r s namely  B r a s s i c c a napus and B. campestris had been produced i n Canada. These were low  in both e r u c i c a c i d  g l u c o s i n o l a t e s . The name 'Canola' was apply  i n Canada to a l l "double  and  adopted  i n 1979  to  low" c u l t i v a r s . Crushed canola  seed y i e l d s approximately 40% o i l and 57% meal of which 3539%  i s protein  (Bell,  1984;  Sanchez and C l a y p o o l , 1983).  c a n o l a meal used as a p r o t e i n supplement i n l i v e s t o c k i s u s u a l l y a mixture of the two and J e f f e r s ,  1976)  g l u c o s i n o l a t e s per gram (Sanchez Canada-wide survey conducted  to grade  (Bell  of  and C l a y p o o l , 1983). A  by B e l l and J e f f e r s  showed that a t y p i c a l canola sample c o n t a i n e d 7.0 of g l u c o s i n o l a t e s . T h i s was  diets  "double low" c u l t i v a r s  and c o n t a i n s l e s s than 3 mg  The  (1976) mg  per gram  a t t r i b u t e d to inadequate  cleaning  standards. Such h i g h l e v e l s of g l u c o s i n o l a t e s would  show more p o t e n t i a l e f f e c t on the f e e d i n g v a l u e of c a n o l a than any other feed component. Sharma et a l • (1977) observed that rapeseed  (a double  low c u l t i v a r ) at 25% of the g r a i n  d i d not decrease t o t a l dry matter However, Waldern g r a i n consumption  i n c l u d i n g Tower mixture  intake by H o s t e i n cows.  (1973) r e p o r t e d a s i g n i f i c a n t  reduction in  by the d a i r y cows when commercial . .64  rapeseed  meal was  fed at 27%  of the  dry matter i n t a k e . No  reduction  s i l a g e dry matter intake and  g r a i n mix  or  11.8%  of the  in g r a i n consumption  by d a i r y cows was  reported  Walsh (1976) when a double zero rapeseed meal  included  at 0,  11 or 22%  d i f f e r e n c e may  F i s h e r and  34%  was  glucosinolate  lactose contents  of the milk c o n s t i t u e n t s .  They  significant difference  (P>0.05) i n the of the  mixture was  discrepancies  comprised of c a n o l a  meal. The  grain  34%  The l e v e l of  canola  intake of the  palatability Alfalfa  containing  meal.  above r e s u l t s show that canola 13%  rations  of the  meal can  be  fed at a  t o t a l d i e t dry matter or 26%  of  the  c o n c e n t r a t e dry matter i n e a r l y l a c t a t i o n with  no  problems. (Medicago s a t i v a ) o f f e r s a source of  supplemental feed which may  supply moderate amounts of both  degradable p r o t e i n with a balanced amino a c i d p r o f i l e s o l u b l e c a r b o h y d r a t e s . Some work quoted by Hunt that  in  r e s u l t s were a t t r i b u t e d to e i t h e r the h i g h e r o i l  content and/or reduced feed 22 and  and  included  same parameters mentioned above, when 25%  two  This  rapeseed meal i n the g r a i n m i x t u r e s . Sharma et a l .  (1977) observed no  the  Fisher  Walsh (1976) observed a s i g n i f i c a n t r e d u c t i o n  t o t a l production  22 and  by  meals used.  in milk y i e l d , b u t t e r f a t , p r o t e i n and the  or  l e v e l s of the g r a i n m i x t u r e s .  be r e l a t e d to a v a r i a t i o n i n the  content of the v a r i o u s  total  and  (1985) showed  lambs fed wheat straw supplemented with dehydrated . .65  a l f a l f a had a g r e a t e r dry matter  i n t a k e compared with lambs  supplemented with soybean meal. H e i f e r s f e d only ground and pelleted  sun-cured  alfalfa  gained weight s i g n i f i c a n t l y  than the h e i f e r s f e d only p e l l e t e d dehydrated ( D i n i u s e t a l . , 1975). Other h e i f e r s f e d sun-cured gain than those Heat Treatment  faster  a l f a l f a meal  o b s e r v a t i o n s made were that  alfalfa  f e d dehydrated  r e q u i r e d l e s s feed per u n i t of alfalfa  meal.  of P r o t e i n Supplements.  Treatment of a good q u a l i t y p r o t e i n such as canola or dehydrated to  alfalfa  with heat, should allow adequate n i t r o g e n  become a v a i l a b l e f o r maximum rumen m i c r o b i a l growth. I t  should a l s o allow s i g n i f i c a n t amounts of the d i e t a r y to  protein  bypass ruminal d e g r a d a t i o n . Thus the e f f i c i e n c y of  utilization  by the animal  should be improved. Numerous  approaches have been used  to enhance the r e s i s t a n c e of  d i e t a r y p r o t e i n to p r o t e o l y s i s and deamination e.g  t r e a t i n g with; heat  i n the rumen  ( T a g a r i e t a l . , 1962; M i r et a l . ,  1984;  S t e r n et a l . , 1985), t a n n i c a c i d  1974)  formaldehyde (Nishimuta  (Nishimuta  et a l . ,  et a l . , 1974;) and with blood  meal (Mir et a l . , 1984). Heat treatment decreased  solubility  of g r a i n s and forages  substantially  of p r o t e i n s (Nishimuta  et a l . ,  1974;  T a g a r i e t a l . , 1962) and the r a t e of d e g r a d a t i o n of p r o t e i n i n the rumen (Mir et a l . , 1984). The h e a t i n g " t h a t occurs d u r i n g p r o c e s s i n g c o u l d reduce it  i s important  ruminal d e g r a d a t i o n .  that temperature . .66  Although  and h e a t i n g d u r a t i o n s be  appropriate, al.,  1985).  protein  optimal c o n d i t i o n s are often Overheating  t o be  fermented  abomasum. M i r two  levels,  minutes.  i n the  that  i s , 110°C  found  degradation  that  i n the  ( S t e r n e_t  failure  both  f o r 2 hours  at e i t h e r  soybean and  of the  f o r c a n o l a meal was  and  120°C two  rate  degradation Their  and  results  also  i n the  agreed  soluble  with those  This c o u l d t h e r e f o r e suggest readily  denatured  Work q u o t e d fed  diets  from  the  12.9%  intestines  f o r a g e s may  temperatures  as  low  maximum t e m p e r a t u r e effectiveness in  10% was  the  of h e a t  i s more  lactating  more amino  (ADIN) t h a n  present heat  i n the  acids  when a  alfalfa. at  temperature Satter,  present,  1983).  and  the  factors  that  determine  in protecting  protein  from  degradation  rumen.  Alfalfa  cows  with  treatment  (Merchen and  carbohydrates  some o f  protein.  protein.  t o 45°C, p r o v i d e d the  soluble  are  the  contained a l f a l f a  undergo e f f e c t i v e  q u a n t i t y of  meal  absorbed  Insoluble Nitrogen  40  of  canola protein  mix  when t h e d i e t  as  were  ruminal  (1986) showed t h a t  s u s t a i n e d f o r 3 months o r more  Moisture,  fraction  i s soybean  grain  amount o f 8 t o  of  reduced  of L i n d b e r g e t a l . (1982).  that  than  Satter  Detergent  more n o r m a l  is  by  heat  c o n t a i n i n g 65%  Acid  Ensiled  by  the  levels  significantly  reflected  in both  canola at  heating  degradability  the d e c r e a s e  the  f o r 20  (P<0.05). T h e s e r e d u c t i o n s i n p r o t e i n by  of  rumen o r b e i n g d i g e s t e d i n t h e  e t a l . (1984) h e a t e d  They  protein  could result  unknown  dehydration occurs at a r e l a t i v e l y . .67  high  temperature  f o r a short d u r a t i o n (Goering, 1976). The net  r e s u l t c o u l d be s i m i l a r to o v e r h e a t i n g , v i z , decreased animal performance.  Goering  (1976) observed that o v e r h e a t i n g of  dehydrated a l f a l f a may be caused by o v e r d r y i n g ; that  i s , as  long as the feed p a r t i c l e has water e v a p o r a t i n g from i t , the temperature  of the p a r t i c l e w i l l be l e s s than  100°C, and  o v e r h e a t i n g or damage w i l l be s l i g h t . When the p a r t i c l e i s almost dry and the a i r temperature  around  i t i s much h i g h e r ,  then the p a r t i c l e would probably overheat. The damage to the p r o t e i n appears  to i n v o l v e the non-enzymatic  browning  r e a c t i o n s . Water, low pH and heat are i n v o l v e d i n these r e a c t i o n s , however the net r e a c t i o n  i s a condensation of  carbohydrate d e g r a d a t i o n products with p r o t e i n 1962). Van Soest a l s o enzymatic  browning  (Van Soest,  i n d i c a t e d that below 80°C, non-  r e a c t i o n s have only s l i g h t  e f f e c t s on the  s o l u b i l i t y of the forage p r o t e i n . K n i p f e l et a l . ,  (1983)  observed that dry h e a t i n g of a l f a l f a at 105°C f o r up to 1440 min  resulted  i n a r e d u c t i o n of i n v i t r o o r g a n i c matter  d i g e s t b i l i t y by rumen microbes. Increases i n A c i d  Detergent  I n s o l u b l e N i t r o g e n (ADIN) and N e u t r a l Detergent F i b r e (NDF) were a l s o  observed.  .68  MATERIALS AND METHODS Animals. Twenty four l a c t a t i n g d a i r y cows i n mid to e a r l y l a c t a t i o n were used. The f i r s t  group of cows was a l l o c a t e d t o  the canola r a t i o n s . T h i s group c o n s i s t e d of twelve top milk producing cows from the s e l e c t e d herd of 24 animals. T h e i r average  l i v e w e i g h t and milk y i e l d per day was 601.8 s.e 21.2  and 30.45 s.e 2.36 kgs r e s p e c t i v e l y . Group two was a l l o c a t e d to  the a l f a l f a  r a t i o n s . The average  l i v e w e i g h t and milk y i e l d  per day was 573.3 s.e 33.8 and 22.7 s.e 1.96 kgs r e s p e c t i v e l y . A l l animals were balanced f o r i n i t i a l p r o d u c t i o n and then a l l o c a t e d randomly t o each w i t h i n groups, l a t e r dropped  f i v e animals i n the a l f a l f a from the experiment.  treatment  treatment were  T h i s took p l a c e at the  beginning of p e r i o d t h r e e . Feeds. Orchard grass hay was chopped at two c u t lengths to g i v e weighted mean p a r t i c l e l e n g t h s of 14.19 and 1.71 mm. treatment was done by moist h e a t i n g i n t r a y s  (500 kgs.  c a p a c i t y ) i n a c l o s e d draught oven at 125°C oven for  Heat  temperature  2 hours to a t t a i n 80-85°C i n t e r n a l feed temperature. The  feed was then allowed to c o o l to room temperature  p r i o r to  mixing. Ration F o r m u l a t i o n . The c o n c e n t r a t e s were then made up based on e i t h e r canola meal or dehydrated a l f a l f a meal (see appendix 1). . .69  Design. Each p r o t e i n either 4*4  short  Latin  duration for  All  (SH) o r l o n g  was  s t u d i e d i n combination  with  (LH) c h o p p e d o r c h a r d g r a s s hay. A  S q u a r e s was e m p l o y e d , w i t h and a 7 day a d a p t a t i o n  each p r o t e i n The  source  f o u r p e r i o d s o f 28 d a y s  interval  between t h e p e r i o d s  source.  four treatments  r a t i o n s were o f f e r e d  were s e t up a s shown a t 40:60  forage  i n Appendix  2.  to concentrate  ratio.  Records and Sample A n a l y s i s . All  cows were w e i g h e d e v e r y  two weeks a f t e r  m i l k i n g . M i l k p r o d u c t i o n and f e e d F e e d was  offered  ad l i b i t u m  (<10%) b e i n g p r e s e n t taken for  every  As w e l l , were o b t a i n e d  a s m a l l amount  (500g) sample was  daily.  of weighback were  then  obtained  hay and f e e d s a m p l e s  (1-2 kg)  in a period.  a minimum o f f i v e i n the l a s t  week o f e a c h p e r i o d f o r p a r t i c l e  determination. Composite milk  taken day  i n t a k e were r e c o r d e d  Weighback and f e e d s a m p l e s  week. A c o m p o s i t e  each treatment  size  daily.  with  the morning  from  samples  t h e two m i l k i n g s  f o r composition (morning  and e v e n i n g )  o f t h e p e r i o d . M i l k i n g was done t w i c e  interval  o f 12  Faecal  samples  were  on t h e l a s t  i n a d a y , w i t h i n an  hours.  A minimum of f o u r were o b t a i n e d  analysis  "Grab" s a m p l e s of t h e f a e c e s p e r cow  i n the l a s t  week o f e a c h e x p e r i m e n t a l  period.  f o r cows i n t h e same g r o u p were c o m p o s i t e d . .70  to  give a s i n g l e sample. Chemical a n a l y s i s , CP, ADF, NDF methods), i n c l u d i n g A c i d  Insoluble  (see Chapter One f o r  Ash (Van Keulen and Young,  1977) and ADIN (Goering and Van Soest, composited f a e c a l and feed  1970) was done on the  samples.  A l l c o n c e n t r a t e s were t e s t e d  f o r rumen d e g r a d a b i l i t y and  s t a t i s t i c a l d i f f e r e n c e s as set out i n Chapter one. A 4(protein  supplements) * 6(Incubation i n t e r v a l s ) f a c t o r i a l  arrangement i n a completely radomized design was used f o r each p r o t e i n c o n c e n t r a t e . The i n c u b a t i o n 6, 12, 18, 24 and 36 hours.  .71  periods  used were 1,  RESULTS Feed  composition. Table 7 shows the composition of the f e e d s t u f f s used.  The c o n c e n t r a t e s were r e l a t i v e l y  isonitrogenous. A l f a l f a  r a t i o n s were higher i n both ADF and NDF content than c a n o l a rations. Table 7: Composition Ration component:  of the r a t i o n  N u t r i t i o n a l composition (%). ADF  NDF  12.35 12.25 13.01 12.65 14.03  8.56 9.20 17.71 18.65 39.87  18.54 20.22 25.84 27.09 55.57  0.32  5.67  6.72  0.011  21.79a 21.57a 27.33b 28. 18b  33.65 34.95 37.86 38.24  AI A 1 .76a 1 .78a 1 .82a 1 .92a  1 .76  1.12  CP OC HC OA HA Orchard  grass hay S.E.M  Complete r a t i o n OC HC OA HA  feedstuffs.  base**:  S.E.M  12.77a 13.07ba 14.05b 13.60b 0.28  ADIN* 0. 157 0. 1 77 0. 1 96 0.209  0.04  Values with d i f f e r e n t l e t t e r s are d i f f e r e n t at (P<0.05) *%ADIN as a f r a c t i o n of dry sample weight. * * N u t r i e n t composition values were c a l c u l a t e d on the b a s i s of the feed consumed. D e g r a d a b i l i t y of c a n o l a and a l f a l f a  concentrates.  A f t e r 24 hours of i n c u b a t i o n , a s i g n i f i c a n t p r o p o r t i o n of the c o n c e n t r a t e s DM and CP had been degraded i n the rumen. There were s l i g h t  i n c r e a s e s i n DM d e g r a d a b i l i t y as the  experimental p e r i o d progressed ..72  (Table 8 ) . Heat  treating  canola meal r e s u l t e d i n s i g n i f i c a n t DM and CP d e g r a d a b i l i t y  (P<0.05) decrease  i n the  (Table 9 ) .  Both i n c u b a t i o n time and heat treatment  a f f e c t e d DM and  CP d e g r a d a b i l i t y of a l f a l f a and canola c o n c e n t r a t e s significantly  (P<0.05). Heat t r e a t e d r a t i o n s were  significantly  l e s s degradable  i n the rumen than the unheated  ones (Table 9 ) . The degradation r a t e constants shown i n Table calculated  10 were  from F i g u r e s 5,6,7 and 8.  Table 8: Mean extent of DM and CP degradation over the experimental d u r a t i o n - i n s i t u . Mean extent of degradation Period  DM  1 2 3 4  63.23a 66.08b 66.81b 64.45ab S.E.M  Values with d i f f e r e n t  0.81  CP 46.57a 47.96a 50.81a 52.29a 1.30  l e t t e r s are d i f f e r e n t a t (P<0.05).  Table 9: Mean extent of DM and CP degradation for canola and a l f a l f a based c o n c e n t r a t e s - i n s i t u . Ration treatment:  Mean extent of degradation DM  CP  Unheated c a n o l a Heated canola  66.91a 63.38b  52.14a 46.67b  Unheated a l f a l f a Heated a l f a l f a  59.35a 54.59b  46.52a 42.01b  2.65  2.07  S.E.M Values with d i f f e r e n t  l e t t e r s are d i f f e r e n t at (P<0.05). . .73  Fig 5: % Degradation Vs Rumen Incubation Time. Canola canaanfe-atas —[DM].  100  D  Heated Canola.  Time Incubated in the rumen [hrs]. + Unheated Canola.  74  b  F i g 6: 96 Degradation  Vs Rumen incubation Time. Canola oanosntratea —[CP].  100  •  Heated Canola.  Time Incubated in the rumen [hrs]. + Unheated Canola.  .75  % Degradation Vs Rumen Incubation Time.  F i g 7: 100  Alfalfa Concentrates [DU].  90 -4 80 -4  76  % Degradation Vs Rumen Incubation Time. Alfalfa Concentrates [CP].  20  10 Heated Alfalfa.  —r~ 30  Time Incubated in the rumen [hrs]. + Unheated Afalfa.  77  Table 10: Degradation and a l f a l f a c o n c e n t r a t e s . Degradation  constant  r a t e constants of canola Feed c o n s t i t u e n t DM  Unheated canola cone. a b c Heated canola cone. a b c Unheated a l f a l f a cone. a b c Heated a l f a l f a cone. a b c  CP  46.66 30.00 11.10  1 6.66 61.11 7.50  38.88 34.45 9.49  11.11 58.89 6.30  45.55 24.45 6.90  23.33 40.00 4.80  37.77 27.78 5.11  15.55 45.56 4.10  a= % s o l u b i l i t y , b= p o t e n t i a l l y degradable c= degradation r a t e constant [ % / h r ] . Digestibility  and m i l k  composition  from  fraction  c a n o l a based  rations.  A c i d i n s o l u b l e ash (AIA) was used as an i n t e r n a l  feed  marker. A 93% recovery r a t e (Thonney et a l . , 1979) was used in the d i g e s t i b i l i t y c a l c u l a t i o n s that f o l l o w e d . The model f i t t e d to e x p l a i n the DM d i g e s t i b i l i t y significant  at (P<0.05) and had an R-squared value of 0.61.  Changes over the experimental p e r i o d s i g n i f i c a n t l y a f f e c t e d the DM d i g e s t i b i l i t y . DM d i g e s t i b i l i t y three was s i g n i f i c a n t l y periods  was  (P<0.05)  in period  (P<0.05) higher than the other  (Table 11). Combining heated  chopped hay s i g n i f i c a n t l y . .78  canola with short  (P<0.05) reduced DM  digestibility  (Table  with at  12).  Crude P r o t e i n d i g e s t i b i l i t y  was  an  T h i s model was  R-squared value  (P<0.05). CP in period  (Table  11).  c h o p p e d hay  ADF  at  d i d not  digestibility.  99.9%  of  the  was  the  Period  significant (P<0.05)  experimental  concentrates  explained  using  variation.  a model  had  a  and  t o e x p l a i n the  significant  at  chop ADF  11).  variation  due  to  for  period  two  r a t i o n s were f i t t e d  i n the  model. A l l c a n o l a  l o w e r NDF  significantly 12).  digestibility  c h o p p e d hay  with  significantly  NDF  based  (P<0.05) r e d u c e d  and  NDF  heated canola  than unheated c a n o l a  for  Both c a n o l a  (P<0.01) d i f f e r e n t  Rations  NDF  accounted  calculations only.  was  (P<0.05) l o w e r  (Table  (P<0.01) and  However, t h e  hay  the  significantly others  that  T h i s model  (P<0.05) a f f e c t  t h a n a l l the  (Table  with  CP  were b a s e d on  digestibility  periods  together  (P<0.05) r e d u c e d  total  two  variation.  t r e a t m e n t s had  Short  other  a model  12).  significantly  was  digestibility alfalfa  of  model f i t t e d  digestibility  i n the  significantly  using  significantly  (P<0.05). P r o t e i n t r e a t m e n t  digestibility The  was  heated canola  (Table  f o r 47%  significant length  than  digestibility  accounted  ADF  three  Feeding  digestibility  0.47.  digestibility  higher  short  of  explained  had  rations.  NDF  digestibility. Variation significant  at  due  to d a i l y  (P<0.05), and . .79  intake with  was an  explained  by  R-squared value  a model of  0.28.  Heat treatment of canola p r o t e i n reduced the animals intake s i g n i f i c a n t l y p e r i o d progressed,  (P<0.05) (Table  the d a i l y  (P<0.05) d e c l i n e d (Table significant  effect  There was after  s l i g h t , but not  feed intake  11). Hay  chop l e n g t h d i d not have a  reduction  feed  intake.  i n l i v e w e i g h t gain  As the experiment progressed  significant  experimental  significantly  on the animals v o l u n t a r y  a significant  p e r i o d one.  13). As the  daily  r e d u c t i o n i n the  there was  a  liveweight  changes. Heat treatment and hay milk production  chop length d i d not a f f e c t  significantly.  d u r i n g the experiment  (Table  T o t a l milk y i e l d d e c l i n e d  14). These r e s u l t s  from a model f i t t e d to e x p l a i n the v a r i a t i o n y i e l d . T h i s model was squared value of The  significant  at  were obtained  due  to milk  (P<0.05) and  had an  f a t content  of the milk was  of the t o t a l v a r i a t i o n  due  the model f i t t e d . T h i s was Heated canola  to milk  significantly  the two  f a t , 23% was  significant  at  treatments r e s u l t e d i n  (P<0.05) lower milk p r o t e i n content  (P<0.05) 15).  effects  duration  and  0.25  by  (P<0.05). significantly  than the unheated r a t i o n s  14). The  above, were s i g n i f i c a n t  squared values of 0.24 T o t a l milk  (Table  Out  explained  15). T o t a l milk p r o t e i n d e c l i n e d s i g n i f i c a n t l y  the experimental  R-  0.23.  reduced by the heat treatment of canola meal (Table  (Table  total  over  models f i t t e d f o r  (P<0.05) and had  respectively.  l a c t o s e however, d e c l i n e d . .80  significantly  R-  between the f i r s t and the l a s t two p e r i o d s (Table 14). The models f i t t e d to account  f o r the v a r i a t i o n s  due t o milk  l a c t o s e were s i g n i f i c a n t a t (P<0.05) and had R-squared values based  Table 11: D i g e s t i b i l i t y and d a i l y rations.  Period  feed intake of canola  Digestibility DM  (Prd) 1 2 3 4  66.71a 65.82a 71.36b 66.1Oa  S.E.M  1 .30  CP  ADF  V o l u n t a r y Intake (g/kg Met.body wt)  70.42a 71.35a 74.36b 70.68a  32.10a 17.99b 31.93a 29.52a  159.01a 154.51ab 148.39ab 142.20b  0.91  3.35  3.66  Values with d i f f e r e n t  l e t t e r s are d i f f e r e n t  a t (P<0.05).  Table 12: DM and CP d i g e s t i b i l i t y c o e f f i c i e n t s of canola based r a t i o n s . Canola  ration  D i g e s t i b i l i t y c o e f f i c i e n t (%). DM  OC+LH OC+SH HC+LH HC+SH S.E.M  CP  NDF*  ADF  67. 94a 68. 25a 69. 65a 64. 22b  71 .57a 73. 1 8a 72. 73a 69. 33b  38. 1 0a 31 .35b 27. 79c 20. 9ld  30. 18a 28. 42a 26. 71a 26. 23a  1 .16  0. 86  3. 58  0. 90  Values with d i f f e r e n t l e t t e r s are d i f f e r e n t a t (P<0.05). *Only p e r i o d two values were i n c l u d e d . Table 13: D a i l y feed intake of canola meal treatments. Ration treatment:  D a i l y feed i n t a k e (g/kg met.body wt).  Unheated canola Heated canola  155.31a 146.75b  s. e 2.81 s.e 3.11  Long chop hay Short chop hay  150.38c 151.67c  s. e 3.11 s. e 2.82  Values with d i f f e r e n t  l e t t e r s are d i f f e r e n t . .81  a t (P<0.05).  Table 14: M i l k y i e l d (Yld) and composition experimental d u r a t i o n - Canola based r a t i o n s . Prd  Milk Y l d . (kg)  1 2 3 4  22.45a 19.94ab 17.63b 16.62b  S.E.M  M i l k composition Fat(%) Protein(%) Protein(kg) Lactose(%)  1 .30  2.82a 2.66a 2.75a 3.08a  3.1 5a 3.12a 3.12a 3.25a  0.85a 0.76ac 0.68bc 0.62b  4.88ab 4.89b 4.68a 5.06b  0.09  0.03  0.05  0.08  Values with d i f f e r e n t  l e t t e r s are d i f f e r e n t at (P<0.05).  Table 15: E f f e c t s of canola r a t i o n y i e l d and composition. Ration  Milk Y l d . (kg)  OC HC  LH SH S.E.M  Period 1 2 3 4 S.E.M  on milk  3.11a 2.56b  3.26a 3.06b  0.76a 0.70a  4.95a 4.80a  0.28  0.10  0.03  0.08  19.57a 18.75a  2.82a 2.83a  3.20a 3. 13a  0.76a 0.70a  4.95a 4.80a  0.41  0.005  0.035  0.03  0.08  1 .20  Values with d i f f e r e n t Table  treatments  Milk composition. F a t ( % ) P r o t e i n ( % ) Prote in(kg) L a c t o s e ( % )  20.35a 17.95a  S.E.M  over the  l e t t e r s are d i f f e r e n t at (P<0.05).  16: D i g e s t i b i l i t y of a l f a l f a based  rations.  D i g e s t i b i l i t y c o e f f i c i e n t (%). DM CP ADF 66.77a 65.70a 71.36b 67.15a  70.42a 71.24a 74.36b 71.61a  32.10a 27.61b 31.93a 32.91a  1 .24  0.85  1 .20  Values with d i f f e r e n t  l e t t e r s are d i f f e r e n t at (P<0.05). . .82  Table  17: DM and CP d i g e s t i b i l i t y of a l f a l f a  Treatment  D i g e s t i b i l i t y c o e f f i c i e n t (%). DM NDF* ADF CP  OA+LH OA+SH HA+LH HA+SH  67. 94a 69. 29a 69. 53a 64. 22b  S.E.M  23 1 .  71 .57a 74. 1 2b 72. 62ab 69. 33c  20 . 23a 24 • 69b 22 .88c 20 .22a  30. I8ab 31 .81b 26. 33a 26. 23a  1 .09  40 1 .  01 1 .  Values with d i f f e r e n t l e t t e r s a r e d i f f e r e n t *Only p e r i o d two v a l u e s were i n c l u d e d . Table  18: D a i l y  Treatment  V o l u n t a r y feed intake (g/kg met.wt) 156.76a 146.59b  s.e 2.87 s. e 3.00  Long chop hay Short chop hay  150.22a 153.13a  s. e 3.00 s. e 2.87  Values with d i f f e r e n t  l e t t e r s are d i f f e r e n t  Table 19: M i l k y i e l d and composition treatments.  1 2 3 4 S.E.M  a t (P<0.05).  feed intake and ADF d i g e s t i b i l i t y .  Unheated a l f a l f a Heated a l f a l f a  Prd  treatments.  a t (P<0.05).  for a l f a l f a  M i l k composition Milk Y l d . (kg) F a t ( % ) Fat(kg) L a c t o s e ( % ) P r o t e i n ( k g & %) 19.39a 17.08ab 15.78b 14.47b 1 .05  4.11a 3.81a 4.1 3a 2.92b  0.78a 0.67ab 0.64b 0.52b  4.84a 4.87abc 4.70b 5. 1 2c  0.63b 0.59ab 0.54a 0.54a  3.33ab 3.39ab 3.46b 3.1 5a  0.28  0.05  0.09  0.02  0.07  Values with d i f f e r e n t  l e t t e r s are d i f f e r e n t  .83  at (P<0.05).  Table 20: Milk y i e l d and composition of treatments. T r e a t - Milk Y l d . ment (kg) Fat OA HA  14.92a 18.44b  S.E.M  1 .76  LH SH  17.20a 16.15a  S.E.M  0.53  alfalfa  M i l k composition (% & kg) P r o t e i n ( % & kg)  3.54a 3.93a  0.56a 0.74b  3.34a 3.31a  0. 53a 0.61b  4.74a 5.03b  0.20  0.09  0.02  0.04  0.15  3.96a 3.53b  0.68a 0.61a  3.38a 3.29a  0. 58a 0.56a  4.87a 4.91a  0.22  0.04  0.05  0.01  Values with d i f f e r e n t l e t t e r s are d i f f e r e n t at of  Lactose(%)  0.02 (P<0.05).  0.35 and 0.27 r e s p e c t i v e l y .  Digestibility  and m i l k  composition  DM d i g e s t i b i l i t y was s i m i l a r p e r i o d three  of a l f a l f a  based  rations.  i n the other p e r i o d s  (Table 16). Ration combinations  except  based on long  chop hay had s i m i l a r l e v e l s of DM d i g e s t i b i l i t y . However, heated  a l f a l f a combined with short chop hay r e s u l t e d i n a  significant ration  (P<0.05) r e d u c t i o n i n DM d i g e s t i b i l i t y of the  (Table 17). These e f f e c t s were observed  i n a model  f i t t e d to e x p l a i n DM d i g e s t i b i l i t y . The model was s i g n i f i c a n t (P<0.05) and accounted  f o r 66% of t o t a l  variation.  CP d i g e s t i b i l i t y of a l f a l f a r a t i o n s was s i g n i f i c a n t l y higher  i n p e r i o d three than  i n the other  experimental  p e r i o d s . V a r i a t i o n due t o CP d i g e s t i b i l i t y was e x p l a i n e d by a model s i g n i f i c a n t at (P<0.05) and with an R-squared value of 0.54.  Further o b s e r v a t i o n s r e v e a l e d that combining short  chopped hay with unheated a l f a l f a i n c r e a s e d CP d i g e s t i b i l i t y . .84  significantly  (Table  heated a l f a l f a to  the  had  and  short  observed  (Table  16).  of  0.62  and  Heating  was  had  two  18).  t h a n a l l the  (P<0.05) but with  long  model f i t t e d  (Table  18).  with  (P<0.05) s i g n i f i c a n t Liveweight  gain  NDF  the  gain  up  period,  t o the  fourth  (P<0.05)  R-squared  ADF value  unheated a l f a l f a higher  rations  based  NDF  (Table  17).  Unheated  + s h o r t chop  digestibility. r a i s e d NDF  digestibility  to explain  i n the  canola  s e c t i o n above.  the  reduced  daily  intake  m o d e l , R<  hay  Feeding  fitted  feed  NDF  intake  showed  significantly  was  equal  to  0.30  at  level. was  a f f e c t e d by  (P<0.10). A l t h o u g h a n i m a l s g a i n e d experimental  values  model  to explain  In  an  lower  it  (P<0.01).  c h o p hay  treating alfalfa  digestibility,  heated a l f a l f a  low  is explained  (P<0.05)  heated  significantly  significantly  other  and,  digestibility  heat  at  fed together  (P<0.05). The  that  had  T h i s model had  significantly  The  resulted in a  resulted in s i g n i f i c a n t l y  heated a l f a l f a  digestibility of  r e s u l t e d i n lower  significant  + l o n g c h o p hay  similar  A combination  t o e x p l a i n ADF  alfalfa  (Table  digestibility alfalfa  fitted  that period  Chopped hay concentrate  diets.  CP  with  digestibility.  model  digestibility  fed together  (P<0.05) h i g h  c h o p p e d hay  (P<0.05) l o w e r CP From the  Long c h o p p e d hay  a similar  unheated a l f a l f a  alfalfa  was  17).  there  was  period. . .85  a  the  weight  experimental throughout  reduction  i n the  period the  rate  of  Heat  treating  increases  i n milk  significant  alfalfa pellets  experimental  (Table 20).  production  (P<0.05)  duration progressed  (Table 20).  significant  four  at  (Table  significantly  was  also  (Table  to  with  an R  (  of  19). F e e d i n g raised  diets  0.38.  Milk  f a t content  a t (P<0.05)  and  and had R  b a s e d on h e a t e d milk  fat production.  f a t content  values  alfalfa  i n f l u e n c e the was  higher  The m o d e l s  i t s total (  in period  period milk f a t  the t o t a l  (Table 20).  milk  b a s e d on a model  butter f a t content  i n the t o t a l  particle  on t h e t o t a l  l o n g c h o p a l f a l f a hay d i e t s .  explain butter  significant  1 9 ) . Hay  effect  also a  as the  of a l f a l f a d i d n o t however,  f a t content  (P<0.05)  lower  (P<0.05)  treatment  butter  and w i t h  reflected  significantly Heat  (P<0.05)  significant  T h e r e was  The above r e s u l t s were  The  production  in  d e c l i n e i n milk y i e l d  l e n g t h d i d not have a s i g n i f i c a n t produced  resulted  yield  o f 0.43  fitted  were and  0.46  respect i v e l y . Heating protein R  (  a l f a l f a protein  content  value  of 0.28,  due t o t o t a l Period period  t h e model  protein  was  (P<0.05)  ( P < 0 . 0 5 ) . W i t h an  between  at  1 9 ) . T h e r e was  the milk  with heat . .86  (P<0.05).  lactose content,  (Table  two and t h e o t h e r s . M i l k  significantly  total  f i t t e d to e x p l a i n the v a r i a t i o n  t h r e e had t h e l o w e s t  difference  i n c r e a s e d the  significantly  significant  f o u r had t h e h i g h e s t  significant period  of the milk  ( T a b l e 20)  lactose  lactose content treated a l f a l f a  while however  content i n increased rations  no  (Table an  2 0 ) . The model  fitted  R - s q u a r e d v a l u e o f 0.37  .87  t o e x p l a i n t h e above  and was  significant  at  results  had  (P<0.05).  DISCUSSION Feed  composition.  The s l i g h t  i n c r e a s e i n NDF with heat treatment  (Table  7), c o u l d p o s s i b l y be a s s o c i a t e d with the f i b r e n i t r o g e n (N). It  i s p o s s i b l e that before  the p r o t e i n supplements were  heated, most of the f i b r e N was a s s o c i a t e d with ADF c e l l u l o s e ) . After heating,  (ligno-  the a d d i t i o n a l f i b r e N was  a s s o c i a t e d with h e m i c e l l u l o s e . K n i p f e l et a l • (1983) observed a similar Soest  r e l a t i o n s h i p when a l f a l f a meal was dry heated. Van  (1965) has a l s o suggested that M a i l l a r d r e a c t i o n s might  cause b i n d i n g of the p r o t e i n to i n d i g e s t i b l e f r a c t i o n s of the c e l l w a l l . A c i d detergent  carbohydrate  insoluble nitrogen  (ADIN) i n c r e a s e d f o l l o w i n g h e a t i n g . T h i s f u r t h e r i n d i c a t e s that some a s s o c i a t i o n c o u l d have o c c u r r e d protein  on h e a t i n g the  supplements.  The n u t r i e n t s i n the complete r a t i o n s were  similar  (P<0.010) w i t h i n the main treatments c a l c u l a t e d on the b a s i s on the feed consumed d i d very l i t t l e  (Table 7 ) . I t i s p o s s i b l e t h a t animals  s e l e c t i o n at feeding.  Degradability of canola  and a l f a l f a  concentrates.  For both Canola and A l f a l f a c o n c e n t r a t e s s o l u b l e f r a c t i o n s (a) and the degradation decreased  the c o n c e n t r a t e .  10), the  r a t e c o n s t a n t s (c)  with heat treatment. In a l l cases  degradable f r a c t i o n  (Table  the p o t e n t i a l l y  (b) of the DM i n c r e a s e d with h e a t i n g of  K n i p f e l et a l . (1983) observed an i n c r e a s e  in the h e m i c e l l u l o s e components of NDF when a l f a l f a was . .88  heated between 480 and 1440 minutes. He a l s o noted a s l i g h t decrease i n the t o t a l n i t r o g e n with the same temperatures. With h e a t i n g of c a n o l a c o n c e n t r a t e , both s o l u b l e CP fraction  (a) and the p o t e n t i a l l y degradable CP f r a c t i o n  d e c r e a s e d . I t i s p o s s i b l e that M a i l l a r d r e a c t i o n s may caused the p r o t e i n to b i n d on to i n d i g e s t i b l e  (b)  have  carbohydrates  in the c e l l w a l l . The p o t e n t i a l l y degradable CP f r a c t i o n  (b)  c o u l d a l s o have been reduced through the formation of s e v e r a l c r o s s l i n k a g e s or through  i n t e r a c t i o n s with other p l a n t  components. The f a c t that ADIN content i n c r e a s e d by  12.7%  (Table 7) between o r d i n a r y and heated c a n o l a c o n c e n t r a t e s shows the p o s s i b i l i t y of p r o t e i n heat damage to have been quite high. Although the s o l u b l e CP f r a c t i o n  (a) decreased with the  h e a t i n g of a l f a l f a c o n c e n t r a t e s , the p o t e n t i a l l y fraction  (b) f o r both DM and CP, i n c r e a s e d with heat  treatment. The i n c r e a s e i n the p o t e n t i a l l y fraction  degradable  degradable  (b) f o r the DM c o u l d be a t t r i b u t e d to some degree of  p r o t e i n heat damage. However,  the i n c r e a s e i n the "b"  f r a c t i o n of CP i s the product of s t r u c t u r a l t r a n s f o r m a t i o n of the p r o t e i n 6.6%  ( d e n a t u r a t i o n ) . The i n c r e a s e i n ADIN content  was  (Table 7) as compared to 12.7% f o r c a n o l a above. T h i s  shows that heat treatment protected  for a l f a l f a  concentrates possibly  i t s p r o t e i n and d i d not a f f e c t  the amino a c i d s  d i g e s t i b i l i t y and a v a i l a b i l i t y as a d v e r s e l y as i t d i d with c a n o l a c o n c e n t r a t e s . A more p o s i t i v e response would t h e r e f o r e . .89  be expected on feeding heated a l f a l f a , alfalfa  than the unheated  concentrates.  Canola based r a t i o n s .  Although the animals gained  weight throughout the  experiment, the r a t e of gain d e c l i n e d with  the l a c t a t i o n  p e r i o d . As a r e s u l t of reduced energy and p r o t e i n demands, due  to the dropping  milk y i e l d , v o l u n t a r y  feed  intake would  be expected to decrease. The  slight  i n c r e a s e i n p e r i o d three d i g e s t i b i l i t y  values  c o u l d be due to v a r i a t i o n s i n the heat treatment of the canola c o n c e n t r a t e .  A reduction  would be expected to r e s u l t The rations rate,  i n the amount of heat a p p l i e d  i n i n c r e a s e d CP d i g e s t i b i l i t y .  i n c r e a s e d DM and CP d i g e s t i b i l i t y with (Table  long chop hay  12), c o u l d be a t t r i b u t e d t o a reduced passage  i n c r e a s e d rumen r e t e n t i o n time and hence enhanced  rumination  and reduced i n t a k e . Increased  would r e s u l t  hay p a r t i c l e  size  i n the i n c r e a s e of the time a v a i l a b l e f o r  m i c r o b i a l attachment to the d i g e s t a , and thus i n c r e a s e rumen fermentation.  Work by K e r l e y et a l . (1985), Pearce and Moir  (1964) and a l s o Welch, (1986) has shown the e f f e c t s of rumen r e s i d e n c e and passage r a t e on d i g e s t i b i l i t y . Welch a l s o observed that p l a s t i c rumination  ribbons,  7-cm long r e q u i r e d  and p a r t i c l e s i z e r e d u c t i o n before  extensive  they c o u l d pass  from the rumen. The  decrease i n NDF d i g e s t i b i l i t y  with  short chop hay  was c o n t r a r y to what was expected i n view of the i n c r e a s e d . .90  surface area. hay,  an  I t i s however p o s s i b l e that with  increase  e f f e c t on NDF  i n the r a t e of the d i g e s t a passage r a t e  digestibility  was  greater  than the  s u r f a c e area e f f e c t . Comparing the o r d i n a r y treatments, a r e d u c t i o n by h e a t i n g  i . e the  hemicellulose  the short chop  i n NDF  result  fraction  to heated  digestibility  canola  c o u l d be caused  of p r o t e i n a s s o c i a t i o n with  ( K n i p f e l et a l . , 1983;  1982). T h i s might r e s u l t  increased  Van  the  Soest,  i n M a i l l a r d r e a c t i o n s , thus  causing  b i n d i n g of the p r o t e i n to i n d i g e s t i b l e carbohydrate f r a c t i o n s of the c e l l The  wall.  s i m i l a r DM  chop r a t i o n s (Table  and  CP d i g e s t i b i l i t y  12),  an a l t e r e d fermentation  could p o s s i b l y represent  fermentation,  would not be expected f o r CP,  the e f f e c t s  but  reduced  with ADF  and  digestibility NDF.  although heat t r e a t e d r a t i o n s may increased  when heated canola short  concentrate  rations,  have encountered  rumen bypass. DM was  increased  digestibility  fed together  with  declined the  hay. Intake i s n e g a t i v e l y  (Van  NDF  d e c l i n e d s i g n i f i c a n t l y with heat treatment. A  s i m i l a r case c o u l d be made f o r the short chop hay  passage and  long  s i t e v i z : With the heated r a t i o n s  a t t r i b u t e d to lower t r a c t  digestibility  between the  r e l a t e d to the d i e t a r y NDF  Soest et a l . , 1984). Hence, i n c r e a s e d NDF  would be a s s o c i a t e d with  increased voluntary  shows that the unheated r a t i o n s had digestibility  a higher  than the heated r a t i o n s . Table .  .91  content  digestibility i n t a k e . Table NDF 13 shows the  12  voluntary  feed intake of the heat  significantly  lower  p o s s i b l y caused on heat  t r e a t e d r a t i o n s was  than the unheated r a t i o n s . T h i s was  by the i n d i g e s t i b l e M a i l l a r d products  treatment  formed  with the h e m i c e l l u l o s e f r a c t i o n of NDF and  p r o t e i n . I t i s a l s o noted that the heated higher NDF content  r a t i o n s had a  (Table 7 ) .  As a r e s u l t of d e c l i n e i n the t o t a l milk p r o d u c t i o n over the experimental d u r a t i o n (Table 14), t o t a l milk p r o t e i n and t o t a l milk l a c t o s e d e c l i n e d s i g n i f i c a n t l y . Evidence  to t h i s  i s p r o v i d e d by the f a c t that both milk p r o t e i n and l a c t o s e c o n t e n t s d i d not change s i g n i f i c a n t l y over The  the same p e r i o d .  t o t a l v a l u e s represent a product of the content and the  t o t a l y i e l d . M i l k f a t content but at an i n s i g n i f i c a n t The protein  i n c r e a s e d over the same p e r i o d  level.  s i g n i f i c a n t l y higher l e v e l s of milk f a t and milk r e a l i s e d with unheated c a n o l a r a t i o n s  (Table 15),  c o u l d be a r e f l e c t i o n of the i n c r e a s e d a v a i l a b i l i t y of amino a c i d s and energy energy  f o r milk s y n t h e s i s . Although  a r e interdependent,  i n c r e a s i n g energy  g r e a t e r e f f e c t on milk y i e l d than and Oldham, 1981). The lower l a c t o s e observed  p r o t e i n and supply has a  increasing protein (Broster  l e v e l s of milk p r o t e i n , f a t and  with heated c a n o l a r a t i o n s may p o s s i b l y be  a t t r i b u t a b l e to a reduced p a l a t a b i 1 i t y , reduced degradability  (due to heat damage), and hence reduced  and p r o t e i n supply. In p r a c t i c e ^ than p r o t e i n  rumen CP  i t i s energy  energy  supply r a t h e r  supply which i n f l u e n c e milk p r o t e i n . .92  content  (Broster  and  limiting  i f less  Soest  Oldham,  1981). E n e r g y  digestible  feeds  e t a l . , 1984). A l t h o u g h  provide  the animals  heating  canola  l o w e r CP  meal,  particle  size  and  i t s composition  the  volatile  had  ME,  level  fatty  15).  with  the  nutritional  was  reduced  to  after  because of  ratio  i n the  two  hay  i n the  on  a  milk  ratio  yield  is related  rumen. A  rumen w o u l d promote  this  sizes  effect  Possibly this  remained  to  higher higher  relatively  considered.  the  experiment  d i g e s t i b i l i t y of  component w o u l d h a v e been e x p e c t e d  constant,  i f r a t i o n s were m a i n t a i n e d  treatment  and  except  later  (Van  based r a t i o n s .  Throughout  Period  used  i t i s p o s s i b l e that  acids proportions  f a t . It i s possible that  constant  16)  are  r a t i o n s were f o r m u l a t e d  insignificant  (Table  acetaterpropionate  Alfalfa  forages  become  digestibility.  Hay  milk  t h e ME  and  the  sufficient  w i l l however  f o r DM  three part  and  CP  lactation.  than  r e m o v a l of  In v i e w of  the  feed  intake,  reduced  liveweight  gain  in  l i v e w e i g h t g a i n was . .93  average  the  their  observed  would d r o p due  observed  in  dropped  result  and  had  in  the  production. i n the  their  were  herd,  d i g e s t i b i l i t y and to higher  (Table  milk  i n the  removal would  heat  three.  animals  low  animals  remain  i n terms of  was  five  a v e r a g e cow  d i g e s t i b i l i t y . Their  increased  This  to  d i g e s t i b i l i t y in period  i t i s possible that  more w e i g h t  a higher  composition.  a l s o marks t h e  of  production, gaining  chemical  uniform  any  period  average A  drop that  f o l l o w e d . Heat treatment effectively to non  reduced  of a l f a l f a c o n c e n t r a t e may  the CP d e g r a d a b i l i t y  not have  i n p e r i o d three  u n i f o r m i t y i n the h e a t i n g or i n the mixing of the  r a t i o n s . T h i s would e x p l a i n the i n c r e a s e d DM digestibility S i n c e ADF  observed  and  CP  over t h i s p e r i o d .  content of the d i e t d i d not change  s i g n i f i c a n t l y over the experimental p e r i o d , the lower expected  digestibility coefficient  in p e r i o d two  a t t r i b u t a b l e to random e r r o r perhaps a l s o due problems, contamination  than  i s mainly  to  filtration  or poor marker r e c o v e r y .  High c o n c e n t r a t e r a t i o n s fed to cows r e s u l t rumen fermentation, and hence a low rumen pH C e l l u l a s e a c t i v i t y would then be reduced and  due  in rapid  (Orskov,  (Van Soest,  1982). 1982),  t h e r e f o r e l e s s of the f i b r o u s hay m a t e r i a l would be  degraded i n the rumen. The r e q u i r e l e s s rumination Moir,  1964)  s m a l l e r hay p a r t i c l e s would  ( K e r l e y et a l . , 1985;  and degradation would proceed  Pearce  to a g r e a t e r extent  than w i t h a long p a r t i c l e s i z e hay. F u r t h e r d i g e s t i o n lower  t r a c t would r e s u l t  i n higher CP and NDF  T h i s i s p o s s i b l y what r e s u l t e d s h o r t hay  rations indicated  other r a t i o n s . The  and  i n the  fermentation.  i n the h i g h e r d i g e s t i b i l i t y  i n Table  18 as compared to the  r e s u l t s a l s o showed t h a t hay p a r t i c l e  d i d not c o n t r i b u t e s i g n i f i c a n t l y  of  to DM  and ADF  size  digestibility  f o r the unheated r a t i o n s . I t i s t h e r e f o r e a l s o p o s s i b l e that due  to r e l a t i v e s i m i l a r i t y  i n hay p a r t i c l e  s i z e , passage r a t e  was  not enhanced s i g n i f i c a n t l y by the short hay ..94  particle  s i z e . If passage r a t e remained r e l a t i v e l y constant particle  f o r both  s i z e s , then rumen d e g r a d a b i l i t y would be higher  the short hay  s i z e than with  the longer hay  the g r e a t e r s u r f a c e area of the  with  p a r t i c l e s due  to  former.  As a r e s u l t of heat treatment of the a l f a l f a  rations, a  h i g h extent  of rumen bypass would be expected. With  concentrate  p o r t i o n of the r a t i o n bypassing  the  the rumen, the  i n the rumen would not drop markedly. Hence rumen pH  pH  may  p o s s i b l y have remained r e l a t i v e l y conducive to c e l l u l a s e a c t i v i t y . Short hay  p a r t i c l e s would have g r e a t e r  a c c e s s i b l e to m i c r o b i a l a t t a c k , and  therefore  surface  increased  d i g e s t i o n . K e r l e y et a l . (1985) however observed a passage r a t e with reduced hay i s the net  particle  r e s u l t of d i g e s t i o n and  area  higher  s i z e . Rumen d i g e s t i o n  passage r a t e . I n c r e a s i n g  passage r a t e decreases the time a v a i l a b l e f o r m i c r o b i a l attachment to the d i g e s t a , thus d e c r e a s i n g fermentation. alfalfa ADF  Essentially  + short chop hay  and NDF)  rumen  t h i s would r e s u l t realizing  digestibility  i n the heated  l e s s n u t r i e n t s (DM,  than the unheated a l f a l f a  chop hay.  Results obtained  (Table  case. ADF  d i g e s t i b i l i t y d i d not however show a  response with changes i n the hay Heated a l f a l f a c o n c e n t r a t e more d i g e s t i b l e concentrate  (DM,  CP and NDF)  + long chop hay  a t t r i b u t a b l e to an  CP,  + long  17) show that t h i s was  particle  significant  length.  + long chop hay  r a t i o n s were  than the unheated  (Table  the  alfalfa  1 8 ) . This i s possibly  improved synchrony i n the r e l e a s e of . .95  nitrogen  i n the rumen with heated a l f a l f a  the r a t e of DM  and CP d e g r a d a b i l i t y  r a t i o n s s i n c e both  i n the rumen were  reduced  on h e a t i n g (Table 9). The  lower d i g e s t i b i l i t y c o e f f i c i e n t s observed  heated a l f a l f a  with  r a t i o n s + short chop hay compared with  having s i m i l a r but unheated i n g r e d i e n t s c o u l d be the  rations result  of reduced m i c r o b i a l d e g r a d a t i o n , reduced  r e t e n t i o n time  hence reduced DM  high passage  and CP d e g r a d a b i l i t y and  T h i s i s i n view of the f a c t hay,  that both r a t i o n s had  and  rate.  short chop  and hence p a r t i c l e s i z e remained c o n s t a n t . Reduced  particle  s i z e enhances passage r a t e , thus reducing the extent  of d i g e s t i o n  (Kerley et a l . , 1985). T h i s was  nutrient d i g e s t i b i l i t i e s Table composition  shown i n Table  reflected  17 and  i n the  18.  19 shows the s i g n i f i c a n t changes o c c u r r i n g i n milk throughout  the experiment.  As  lactation  p r o g r e s s e d the t o t a l milk p r o d u c t i o n a l s o d e c l i n e d . Since milk f a t content d i d not change s i g n i f i c a n t l y ,  only the  total  f a t would decrease with l a c t a t i o n p e r i o d . T o t a l milk f a t was c a l c u l a t e d as the product of milk f a t content and  t o t a l milk  y i e l d . Lactose content changed s l i g h t l y . Changes i n the l a c t o s e content c o u l d r e f l e c t due  the changes i n osmotic  to other s o l i d s and m i n e r a l s i n l a t e Heated a l f a l f a  rations resulted  value  lactation.  in s i g n i f i c a n t l y  higher  l e v e l s of milk p r o d u c t i o n , t o t a l milk f a t , t o t a l p r o t e i n a higher milk l a c t o s e content  (Table 20). M i l k f a t and  p r o t e i n contents d i d not change s i g n i f i c a n t l y . Hence the . .96  and  increase and  total  the  fact  heated and  i n milk  contributed  p r o t e i n . The i n c r e a s e that  nutrients  (P<0.10) w i t h  gain.  increased  utilized  Increased  increased  increased  milk  availability i n other  amino a c i d s  f a t and l a c t o s e c o n t e n t  From T a b l e  10, h e a t i n g  yield  could  total fat be due t o  r e s u l t i n g from t h e h i g h l y d i g e s t i b l e  has been o b s e r v e d  1972). W i t h  to the increased  i n milk  r a t i o n s were e f f i c i e n t l y  liveweight  energy  yield  alfalfa  i n milk  yield  and milk f a t  o f b o t h amino a c i d s and  trials  (Orskov  1981; F i s h e r  a v a i l a b l e f o r glucogenesis, could  have b e e n r e a l i z e d .  concentrates  some p r o t e c t i o n o f t h e p r o t e i n  production  from  rumen  also  provided  microbial  degradation. L o n g c h o p hay r e s u l t e d i n i n c r e a s e d and in  hence t o t a l other  trials  been a s s o c i a t e d proportions. and  milk  f a t (Table  (Broster with  A close  fell  2 0 ) . T h i s h a s been  e t a l . , 1981; O r s k o v  t h e rumen v o l a t i l e  fatty  r e l a t i o n s h i p between m i l k  the acetate:propionate  when t h e r a t i o  f a t content  below  .97  ratio 3:1  (P<0.10) observed  1982) and has acids f a t content  was o b s e r v e d , e s p e c i a l l y  (Broster  etal. ,  1981).  SUMMARY AND CONCLUSIONS  In t h i s t r i a l the opening  we s e t out two o b j e c t i v e s as i n d i c a t e d i n  s e c t i o n . From the r e s u l t s o b t a i n e d , the  o b j e c t i v e s were a c h i e v e d . However due to i n t e r a c t i o n between the treatment of the c o n c e n t r a t e and the hay p a r t i c l e  size,  some e f f e c t s c o u l d not be e s t a b l i s h e d s e p a r a t e l y . I t was a l s o e s t a b l i s h e d that the two hay chop lengths had s i m i l a r i n most of the a t t r i b u t e s under Canola based The  effects  investigation.  rations.  d e g r a d a b i l i t y of c a n o l a meal c o n c e n t r a t e was reduced  by heat treatment. T h i s d i d not r e f l e c t a s i g n i f i c a n t damage of c a n o l a p r o t e i n , s i n c e CP d i g e s t i b i l i t y heated r a t i o n s was s i m i l a r to the unheated  heat  of the  rations.  Heat treatment d i d not a f f e c t DM, CP and ADF digestibility heat  s i g n i f i c a n t l y . NDF d i g e s t i b i l i t y decreased with  treatment. Heat treatment a l s o d r a s t i c a l l y  feed  reduced the v o l u n t a r y  intake. Although heat treatment had no s i g n i f i c a n t  e f f e c t on the  t o t a l milk y i e l d ; b u t t e r f a t and milk p r o t e i n c o n t e n t s decreased with heat treatments. M i l k l a c t o s e  remained  r e l a t i v e l y constant. Forage p a r t i c l e  l e n g t h had i t s g r e a t e s t e f f e c t when f e d  together with the heat t r e a t e d r a t i o n s . O v e r a l l . .98  reduced  forage p a r t i c l e  size  CP,  ADF  d i g e s t i b i l i t y . With heat  but  significant  and  NDF  Voluntary with  reduced  change  treatment  voluntary milk  both  lower  content,  similar  for  NDF. increased  t h e r e was  components  DM  feed  ADF  no  with  the  most  of the  size  Total  other  milk  change s i g n i f i c a n t l y  based  and  affect  in  components,  . .99  NDF rations.  in increased  content.  voluntary  including  changes  short  reduced  resulted  lactose  on  s h o r t hay  resulted  treatment  rations  notable  reduced.  fat increased with  size.  protein  rations.  rations  rations  with  CP  particularly  notably with  d i d not  milk  was  With  fat, protein  particle  unheated  d i g e s t i b i l i t y were  i n t a k e . Heat  milk  and  d i g e s t i b i l i t y of heated  hay.  CP  DM  significant  treatment  size  and  i n reduced  than  of h e a t  treatment  However, t h e  except  significantly  milk  reflect  and  decreased  significantly.  not  This could  effect  yield, Hay  lactose  resulted  s i n c e CP  digestibility Heat  treatment  DM,  concentrates.  short p a r t i c l e  c h o p hay,  insignificant  size.  size.  significantly  with  not  forage p a r t i c l e  denaturation  The  i n t a k e was  milk  but  observed  other  degradability.  was  i n lower  i n the  based  Heat  feed  for total  significant  Alfalfa  r e d u c t i o n was  forage p a r t i c l e  Except  different  resulted  feed  intake  l o n g chop milk  in forage  hay.  yield did  particle  GENERAL SUMMARY  The as  first  study  o u t l i n e d i n the  the  r a t e and  studied. flow  results  regimes.  nutrition.  and  on  d a i r y cow  considerations  the  on  optimum t i m e  the  feeding value  development  of  forages  the  ration  the  of  at  their  in this  of  forages  feed of the  critical  involve  potential,  at d i f f e r e n t vital  The  peak q u a l i t y . are  over  would  stages  importance. two  T h i s marks t h e  ..100  the  hand t h e r e f o r e ,  d a i r y cows p l a n e  and  also  results  Feed  samples the  when most  obtained the  use  and of  hence, the  Degradability values  t h e r e f o r e at best  on  of  months a f t e r  time  t h a t were made r e f l e c t  trial  of  for conservation. Information  were a t peak q u a l i t y .  feedstuffs  different  i n f l u e n c e on  were o b t a i n e d  r a i n y season.  to  met.  production  forages  study  6 show  various digesta  were made i n  d a i r y cow  forage  5 and  the f e e d s t u f f s  f e e d samples a t  the  to harvest  recommendations  obtained  of  i s t h e r e f o r e of  in this  the  on  of  4,  the p o s s i b l e c o m b i n a t i o n s  utilization  periods  the  evaluated  hence,  3,  application  s e a s o n s have a m a j o r  Efficient  physiological  the  their  Suggestions  major o b j e c t i v e s  were b a s e d on  o b j e c t i v e s were a d e q u a t e l y  availability,  end  rumen d e g r a d a t i o n  remarks. With  In Kenya,  two  s e c t i o n . Tables  obtained  f e e d s t u f f s i n the  concluding both  of  r a t e s . T h i s extends  feeding the  undertaken with  opening  extent  The  was  u s e f u l as  a  stardard  i n the e v a l u a t i o n of conserved  feed m a t e r i a l s .  I t would a l s o be u s e f u l t o c a r r y out  similar  i n v e s t i g a t i o n s with forages sampled over the dry season. T h i s would p r o v i d e an estimate of the d e c l i n e  in degradability  with m a t u r i t y and such a s p e c t s as d e s s i c a t i o n . Through comparisons seasons,  at v a r i o u s p h y s i o l o g i c a l  feed c o n s e r v a t i o n needs and  supplementation  the type of  r e q u i r e d would be f u r t h e r  L a k s e s v e l a and S a i d for  stages and over the  identified.  (1978) e s t a b l i s h e d the c r i t i c a l  c o r r e c t energy and p r o t e i n  supplementation  forages when used f o r milk p r o d u c t i o n . The  need  of Kenyan  rapid  increase in  p r o t e i n requirement which a r i s e s w i t h l a c t a t i o n has been shown not to be adequately met  by m i c r o b i a l p r o t e i n  supplies  a l o n e . Feeding h i g h l y degradable p r o t e i n s would supply i n s u f f i c i e n t amounts of amino a c i d s to the i n t e s t i n e s over the l a c t a t i o n p e r i o d . As the Kenyan m i l k p r o d u c t i o n i n t e n s i f i e s , a g r e a t e r need w i l l be r e a l i s e d undegradable  f o r use of rumen  proteins.  Canola meal i s used as a p r o t e i n supplement f o r livestock  i n Canada. Canola  i s a g e n e t i c c u l t i v a r of  rapeseed. The p r o d u c t i o n of rape excellent alfalfa and  results  i n Kenya  ( B r a s s i c a napus) gave  (Kidner, 1981). On  i s an e s t a b l i s h e d p r o t e i n  the other hand,  supplement both i n Kenya  i n Canada. Both c a n o l a and a l f a l f a  have a balanced amino  a c i d p r o f i l e conducive to milk p r o d u c t i o n . Heat treatment of these supplements  or any forage e.g desmodium, would be aimed . . 101  at  a l l o w i n g s i g n i f i c a n t amounts of the d i e t a r y p r o t e i n to  bypass ruminal d e g r a d a t i o n . Thus, the e f f i c i e n c y of utilization  by the animal would be  Although  improved.  numerous approaches e x i s t  f o r enhancing  r e s i s t a n c e of d i e t a r y p r o t e i n to p r o t e o l y s i s and in the rumen, heat treatment  the  deamination  i s simple and cheap. I t c o u l d  a l s o be combined with other normal processes e.g o i l c r u s h i n g or  d e h y d r a t i o n . Other  a s p e c t s that have an e f f e c t on  the  rumen turnover r a t e and hence the extent of p r o t e i n degradation  i n the rumen e.g g r i n d i n g need to be  f u r t h e r . In the second and  forage p a r t i c l e  trial  t h e r e f o r e , we  investigated  c o n s i d e r e d heat  l e n g t h as some measures that c o u l d be  used to i n c r e a s e the r a t e of p r o t e i n  . 1 02  bypass.  LITERATURE CITED: A g r i c u l t u r a l Research C o u n c i l . 1980. The n u t r i e n t requirements of ruminant l i v e s t o c k . Commonwealth A g r i c u l t u r a l Bureau. London. B a l c h , C.C. and V.W. Johnson. 1950. F a c t o r s a f f e c t i n g the u t i l i z a t i o n of food by d a i r y cows. 2. F a c t o r s i n f l u e n c i n g the r a t e of breakdown of c e l l u l o s e (Cotton thread) in the rumen of the cow. Br. J . Nutr. 4:389. B e l l , J.M. 1984. N u t r i e n t s and review. J . Anim. S c i . 58:996.  toxicants  i n rapeseed meal: A  B e l l , J.M. and H.F J e f f e r s . 1976. V a r i a b i l i t y i n the chemical composition of rapeseed meal. Can. J . Anim. S c i . 56:269. Broderick, C A . 1975. 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Appendix  1: C o m p o s i t i o n of t h e d a i r y  Canola  based  rations  ration  Components:  100 k g s . mix  Coarse ground b a r l e y C a n o l a meal Molasses Limestone Premix Salt D i c a l c i u m phosphate Alfalfa  based  formulated.  84.946 10.153 1 .667 1 .583 0.833 0.416 0.400  ration  Components:  100 K g s . mix  Alfalfa Barley Molasses Limestone Premix Salt Dicalcium  49.182 46.688 1 .667 0.143 0.833 0.416 1 .070  phosphate  The c o m p o s i t i o n  of the Premix  was;  N u t r i e n t s p e r Kg o f P r e m i x  Components: Vitamin A Vitamin D Vitamin E Selenium Iodine Cobalt Copper Zinc Manganese I ron  1,600,000 320,000 4,000 40 0.3 0.1 5 20 16 16  ..112  IU IU IU mg g g g g g g  Appendix  2. E x p e r i m e n t a l l a y o u t used i n the  trial.  Canola based Treatment 1 Treatment 2 Treatment 3 Treatment 4  -  SH SH LH LH  + + + +  Unheated c a n o l a based cone (OC) Heated canola based cone (HC) OC HC  A l f a l f a based Treatment 1 Treatment 2 Treatment 3 Treatment 4  -  SH SH LH LH  + + + +  Unheated a l f a l f a based cone (OA) Heated a l f a l f a based cone (HA) OA HA  .113  

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