UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Quantification of forage particle length and its effect on intake and chewing behavior in dairy.. Vaage, Alan Stanley 1985

You don't seem to have a PDF reader installed, try download the pdf

Item Metadata

Download

Media
UBC_1986_A6_7 V32.pdf [ 8.37MB ]
[if-you-see-this-DO-NOT-CLICK]
Metadata
JSON: 1.0096829.json
JSON-LD: 1.0096829+ld.json
RDF/XML (Pretty): 1.0096829.xml
RDF/JSON: 1.0096829+rdf.json
Turtle: 1.0096829+rdf-turtle.txt
N-Triples: 1.0096829+rdf-ntriples.txt
Original Record: 1.0096829 +original-record.json
Full Text
1.0096829.txt
Citation
1.0096829.ris

Full Text

c QUANTIFICATION OF FORAGE PARTICLE LENGTH AND ITS EFFECT ON INTAKE AND CHEWING BEHAVIOR IN DAIRY CATTLE  by ALAN STANLEY VAAGE B.Sc,  The U n i v e r s i t y o f B r i t i s h Columbia, 1982  A THESIS SUBMITTED  IN PARTIAL FULFILLMENT OF  THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE  in THE FACULTY OF GRADUATE STUDIES (Department o f Animal S c i e n c e )  We a c c e p t t h i s t h e s i s as c o n f o r m i n g to the r e q u i r e d s t a n d a r d  THE UNIVERSITY OF BRITISH COLUMBIA December, 1985 (c) A l a n S t a n l e y Vaage, 1985  In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department  or  by  his or  her  representatives.  It  is understood  that copying  or  publication of this thesis for financial gain shall not be allowed without my written permission.  ^Clan S. "V^»g4  Department of  Animal S c i e n c e  The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date  DE-6(3/81)  March 7, 1986  ABSTRACT  A method f o r the q u a n t i t a t i o n o f the p a r t i c l e l e n g t h d i s t r i b u t i o n i n processed  f o r a g e was developed,  t e s t e d , and used t o i n v e s t i g a t e the e f f e c t  o f p r o c e s s i n g method and f o r a g e type on p a r t i c l e l e n g t h d i s t r i b u t i o n . The same method was a l s o used to i n v e s t i g a t e the e f f e c t o f f o r a g e l e n g t h on v o l u n t a r y f e e d i n t a k e (VFI) and chewing b e h a v i o r A simple v i b r a t i n g t r a y f o r a g e p a r t i c l e s e p a r a t o r  particle  i n dairy cattle.  (FPS) was  constucted  to s e p a r a t e f o r a g e p a r t i c l e s on the b a s i s o f l e n g t h a l o n e . A l t h o u g h n o t completely  a c c u r a t e , the s e p a r a t o r produced r e p e a t a b l e r e s u l t s  forage p a r t i c l e s 8.25-16.5,  into s i x theoretical length fractions  16.5-33.0, 33.0-66.0 and >66.0  Cumulative  (<3.3,  i n separating 3.3-8.25,  mm).  sample weight u n d e r s i z e o f s e p a r a t e d o r c h a r d g r a s s hay was  f i t t e d by r e g r e s s i o n t o a l i n e a r and two e x p o n e n t i a l e q u a t i o n s , distribution,  and a m o d i f i e d W e i b u l l f u n c t i o n . Only  a  lognormal  the W e i b u l l f u n c t i o n  c l o s e l y f i t these s e p a r a t i o n d a t a . The median p a r t i c l e  l e n g t h (MPL) c o u l d be  p r e d i c t e d by the i n v e r s e o f the B parameter o f the m o d i f i e d W e i b u l l f u n c t i o n w h i l e the use o f the C parameter (named the C o e f f i c i e n t o f Spread (CS)) was proposed as a measure o f the spread o f p a r t i c l e l e n g t h s around a g i v e n median. A l f a l f a and low and h i g h q u a l i t y o r c h a r d g r a s s hays were hammered a 12.7 mm 9.53 mm)  through  s c r e e n and chopped a t 3 t h e o r e t i c a l l e n g t h s o f c u t (3.18, 6.35 and and s e p a r a t e d on the FPS to determine the r e s p e c t i v e d r y matter  (DM), crude p r o t e i n (CP) and a c i d d e t e r g e n t  fiber  (ADF) MPL and CS. The  MPL were based on the weight o f each n u t r i e n t c o l l e c t e d i n each p a r t i c l e l e n g t h f r a c t i o n on the FPS. D i f f e r e n t f o r a g e s , p r o c e s s e d by the same method, produced s i g n i f i c a n t l y d i f f e r e n t  (P < 0.05) DM,  ii  CP and ADF MPL,  and CS.  Furthermore, the d i f f e r e n c e s i n DM MPL significantly  different  also s i g n i f i c a n t the DM  and ADF  and  MPL  MPL,  ratio  between the DM  w i t h i n each f o r a g e  (7.3 and 18.1  mm)  chopped to  two  f o r a g e to c o n c e n t r a t e r a t i o s  (40:60  l e n g t h o f the forage d i d not s i g n i f i c a n t l y  affect  (P < 0.05)  I n c r e a s i n g the f o r a g e to  concentrate  decreased v o l u n t a r y f e e d i n t a k e , i n c r e a s e d  the time spent chewing per kg o f f e e d i n t a k e d u r i n g e a t i n g and and  and  type.  a t two  VFI o r chewing b e h a v i o r .  significantly  There were  and CP MPL,  H o l s t e i n cows were f e d o r c h a r d g r a s s hay  60:40). The p a r t i c l e  (P > 0.05)  from those f o r CP and ADF.  d i f f e r e n c e s (P < 0.05)  Twelve l a c t a t i n g different  (P < 0.05)  and CS between f o r a g e s were  rumination  i n c r e a s e d the number o f b o l i r e g u r g i t a t e d p e r kg o f f e e d i n t a k e d u r i n g  rumination. When d a i r y s t e e r s were f e d timothy-brome hay 13.3 MPL  and  20.0  mm)  a t a 60:40 f o r a g e to c o n c e n t r a t e r a t i o ,  o f the f o r a g e i n the d i e t  spent  idle,  chopped to 4 MPL  significantly  (P < 0.05)  i n c r e a s e d the time spent r u m i n a t i n g and  chewing ( e a t i n g p l u s r u m i n a t i o n ) , and  9.0,  an i n c r e a s e i n the  decreased  the  the t o t a l time  time  spent  i n c r e a s e d the number o f b o l i  r e g u r g i t a t e d p e r kg o f f e e d i n t a k e . These e f f e c t s  o f f o r a g e MPL  b e h a v i o r were d i r e c t l y r e l a t e d to the l o g a r i t h m o f the f o r a g e I n c r e a s i n g the MPL  (5.2,  o f the f o r a g e s i g n i f i c a n t l y  spent chewing p e r b o l u s r e g u r g i t a t e d d u r i n g  iii  decreased  rumination.  on chewing MPL.  (P < 0.05)  the  time  TABLE OF CONTENTS page ABSTRACT  i i  LIST OF TABLES LIST OF FIGURES  v I  viii  ACKNOWLEDGEMENT  x  GENERAL INTRODUCTION  1  CHAPTER 1: D e s c r i p t i o n o f the p a r t i c l e l e n g t h d i s t r i b u t i o n o f chopped f o r a g e u s i n g a simple v i b r a t i n g t r a y Forage P a r t i c l e S e p a r a t o r and a m o d i f i e d W e i b u l l - t y p e f u n c t i o n  4  Introduction L i t e r a t u r e Review M a t e r i a l s and Methods R e s u l t s and D i s c u s s i o n Summary  4 6 24 33 63  CHAPTER 2: The e f f e c t o f p r o c e s s i n g method and f o r a g e type on the p a r t i c l e l e n g t h d i s t r i b u t i o n o f DM, CP and ADF i n processed forage Introduction L i t e r a t u r e Review M a t e r i a l s and Methods R e s u l t s and D i s c u s s i o n Summary  64 64 66 69 73 92  CHAPTER 3: The 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 f o r a g e t o c o n c e n t r a t e r a t i o on i n t a k e and chewing b e h a v i o r i n d a i r y cattle 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  93 93 95 116 126 138 144  GENERAL SUMMARY AND CONCLUSIONS  146  LITERATURE CITED  150  APPENDICES  158  iv  LIST OF TABLES page TABLE I :  TABLE I I :  TABLE I I I :  TABLE IV:  TABLE V:  TABLE V I :  TABLE V I I :  ASAE (1969b) example c a l c u l a t i o n s f o r the d e t e r m i n a t i o n o f the Modulus o f F i n e n e s s o f ground f e e d s t u f f s by s i e v i n g  14  ASAE (1969b) example c a l c u l a t i o n s f o r the d e t e r m i n a t i o n o f the Modulus o f U n i f o r m i t y o f ground f e e d s t u f f s by s i e v i n g  15  Average p e r c e n t o f sample weight (n = 4) o f hand chopped a l f a l f a hay c o l l e c t e d i n each p a r t i c l e l e n g t h f r a c t i o n a f t e r each o f t h r e e s e p a r a t i o n runs on the Forage P a r t i c l e S e p a r a t o r  34  P a r t i c l e l e n g t h d i s t r i b u t i o n s ( p e r c e n t o f sample weight) o f mature o r c h a r d g r a s s hay, chopped a t t h r e e t h e o r e t i c a l l e n g t h s o f c u t (TLC), d e t e r m i n e d by the FPS and by v i s u a l (VIS) s e p a r a t i o n  36  P e r c e n t weight o f p a r t i c l e s c o l l e c t e d i n each t h e o r e t i c a l p a r t i c l e l e n g t h f r a c t i o n on the Forage P a r t i c l e S e p a r a t o r (FPS) t h a t were c o r r e c t l y and incorrectly sized  37  P e r c e n t weight o f sample f o r a g e p a r t i c l e s o f the g i v e n a c t u a l ranges o f p a r t i c l e l e n g t h t h a t were c o r r e c t l y and i n c o r r e c t l y s i z e d by the Forage P a r t i c l e Separator  39  P e r c e n t weight o f a l l p a r t i c l e s f a l l i n g i n t o the c o r r e c t t r a y ( T ) and i n t o t r a y s b e f o r e (-) and a f t e r (+) the c o r r e c t t r a y on the FPS f o r mature o r c h a r d g r a s s hay chopped a t t h r e e t h e o r e t i c a l l e n g t h s o f c u t (TLC)  40  P a r t i c l e l e n g t h d i s t r i b u t i o n s ( p e r c e n t o f sample weight) o f mature o r c h a r d g r a s s hay, chopped a t t h r e e t h e o r e t i c a l l e n g t h s o f c u t (TLC), determined by the Forage P a r t i c l e S e p a r a t o r ( F P S ) and by v i s u a l (VIS) s e p a r a t i o n a f t e r c a l i b r a t i o n o f the FPS  42  P e r c e n t weight o f p a r t i c l e s , c o l l e c t e d i n each t h e o r e t i c a l p a r t i c l e l e n g t h f r a c t i o n on the Forage P a r t i c l e S e p a r a t o r (FPS) t h a t were c o r r e c t l y and incorrectly sized after calibration  42  Q  TABLE V I I I :  TABLE IX:  v  vi  TABLE XIX:  TABLE XX:  TABLE XXI:  TABLE X X I I :  TABLE X X I I I :  TABLE XXIV:  TABLE XXV:  TABLE XXVI:  TABLE XXVII:  TABLE XXVIII:  TABLE XXIX:  TABLE XXX:  D e v i a t i o n between the DM and CP, and DM and ADF median p a r t i c l e l e n g t h s (mm) o f the f o r a g e s hammered through a 12.7 mm s c r e e n (H) and chopped a t t h r e e t h e o r e t i c a l l e n g t h s o f c u t (TLC)  84  DM, CP and ADF c o e f f i c i e n t s o f spread o f the f o r a g e s hammered through a 12.7 mm s c r e e n (H) and chopped a t t h r e e t h e o r e t i c a l l e n g t h s o f c u t (TLC)  88  P a r t i c l e l e n g t h d i s t r i b u t i o n (% sample wt.) and d i s t r i b u i o n parameters o f the s h o r t and l o n g chopped o r c h a r d g r a s s hay  126  N u t r i e n t c o n t e n t (%, DM b a s i s ) o f the c o n c e n t r a t e and s h o r t and l o n g chopped o r c h a r d g r a s s hay used i n the experiment  127  E f f e c t o f f o r a g e median p a r t i c l e l e n g t h on i n t a k e and chewing c h a r a c t e r i s t i c s  128  E f f e c t o f f o r a g e t o c o n c e n t r a t e r a t i o on i n t a k e and chewing c h a r a c t e r i s t i c s  128  E f f e c t o f forage t o c o n c e n t r a t e r a t i o and f o r a g e median p a r t i c l e l e n g t h (mm) on i n t a k e and chewing characteristics  129  P a r t i c l e Length d i s t r i b u t i o n s (% sample wt.) and d i s t r i b u t i o n parameters o f the chopped timothy-brome hay  130  N u t r i e n t c o n t e n t (%, DM b a s i s ) o f the c o n c e n t r a t e and the f o u r l e n g t h s (mm) o f chopped timothy-brome hay used i n the experiment  131  N u t r i e n t c o n t e n t (%, DM b a s i s ) o f the d i e t a r y treatments (40% c o n c e n t r a t e w i t h 60% timothy-brome hay chopped a t f o u r median p a r t i c l e l e n g t h s )  132  E f f e c t o f f o r a g e median p a r t i c l e l e n g t h (mm) on i n t a k e and chewing c h a r a c t e r i s t i c s  133  0  75  R e g r e s s i o n (Y = a + blogX) and BW covariable c o e f f i c i e n t s f o r the e f f e c t o f f o r a g e median p a r t i c l e l e n g t h on chewing and r u m i n a t i o n characteristics  vii  134  LIST  OF  FIGURES page  FIGURE  1:  Forage  FIGURE  2:  Arrangement of 4 groups of obtaining 3 representative forage  FIGURE  3:  Plots  Particle  of  FPS  Separator  separation  25 subsampling boxes for samples of a chopped  data  29 for  low  quality  o r c h a r d g r a s s h a y c h o p p e d a t a T L C o f 3 . 1 8 mm s h o w i n g the f i t of the observed p o i n t s to the p r e d i c t e d l i n e (a) and t h e d i s t r i b u t i o n o f r e s i d u a l s (b) u s i n g t h e regression FIGURE  4:  equation  Y =  a + bX  P l o t s o f FPS s e p a r a t i o n d a t a f o r l o w o r c h a r d g r a s s h a y c h o p p e d a t a TLC o f the f i t of the observed p o i n t s to the (a) and the d i s t r i b u t i o n o f r e s i d u a l s regression equation Y = a + blogX  FIGURE  FIGURE  FIGURE  FIGURE  FIGURE  FIGURE  5:  6:  7:  8:  9:  10:  47 quality 3 . 1 8 mm  showing  predicted (b) u s i n g  line the 48  P l o t s o f FPS s e p a r a t i o n d a t a f o r l o w q u a l i t y o r c h a r d g r a s s h a y c h o p p e d a t a T L C o f 3 . 1 8 mm s h o w i n g the f i t of the observed p o i n t s to the p r e d i c t e d l i n e (a) a n d t h e d i s t r i b u t i o n o f r e s i d u a l s (b) u s i n g t h e regression equation logY = a + blogX  49  P l o t s o f FPS s e p a r a t i o n d a t a f o r l o w q u a l i t y o r c h a r d g r a s s h a y c h o p p e d a t a T L C o f 3 . 1 8 mm s h o w i n g the f i t of the observed p o i n t s to the p r e d i c t e d l i n e (a) and t h e d i s t r i b u t i o n o f r e s i d u a l s (b) u s i n g t h e regression equation Probit Y = a + blogX  50  P l o t s o f FPS s e p a r a t i o n d a t a f o r l o w q u a l i t y o r c h a r d g r a s s h a y c h o p p e d a t a T L C o f 3 . 1 8 mm s h o w i n g the f i t of the observed p o i n t s to the p r e d i c t e d l i n e (a) and t h e d i s t r i b u t i o n o f r e s i d u a l s (b) u s i n g t h e modified Weibull function  51  Changes i n shape o f the m o d i f i e d W e i b u l l cumulative frequency d i s t r i b u t i o n w i t h v a r i o u s B and C parameter v a l u e s when "base e" i s u s e d i n the e q u a t i o n  56  Changes i n shape o f the m o d i f i e d W e i b u l l cumulative frequency d i s t r i b u t i o n w i t h v a r i o u s B and C parameter v a l u e s when " b a s e 2" i s u s e d i n t h e e q u a t i o n  57  Changes i n shape of the m o d i f i e d W e i b u l l cumulative frequency d i s t r i b u t i o n given a f i x e d B parameter v a l u e and t h r e e C p a r a m e t e r v a l u e s when " b a s e 2" i s used i n the equation  59  v i i i  FIGURE 1 1 :  FIGURE 12:  FIGURE 1 3 :  FIGURE 1 4 :  FIGURE 1 5 :  FIGURE 16:  FIGURE 1 7 :  FIGURE 1 8 :  FIGURE 1 9 :  Changes i n shape o f the m o d i f i e d W e i b u l l p r o b a b i l i t y d e n s i t y d i s t r i b u t i o n g i v e n a f i x e d B parameter v a l u e and t h r e e C parameter v a l u e s when "base 2" i s used i n the e q u a t i o n  60  P l o t o f the average observed v a l u e s and p r e d i c t e d r e g r e s s i o n l i n e s (Y = a + blogX) f o r the r e l a t i o n s h i p between crude p r o t e i n c o n t e n t (Y) and p a r t i c l e l e n g t h (X) i n p r o c e s s e d a l f a l f a (ALF) and h i g h (OGH) and low (OGL) q u a l i t y o r c h a r d g r a s s hays  74  P l o t o f the average observed v a l u e s and p r e d i c t e d r e g r e s s i o n l i n e s (Y = a + blogX) f o r the r e l a t i o n s h i p between a c i d d e t e r g e n t f i b e r c o n t e n t (Y) and p a r t i c l e l e n g t h (X) i n p r o c e s s e d a l f a l f a (ALF) and h i g h (OGH) and low (OGL) q u a l i t y o r c h a r d g r a s s hays  75  Dairy c a t t l e i n stanchion s t a l l s i n research area d u r i n g the m o n i t o r i n g o f chewing b e h a v i o r  117  Pneumatic d e v i c e o f the chewing monitor p r e s s u r e impulses from jaw movement  120  f o r producing  Chewing monitor h a l t e r w i t h pneumatic d e v i c e and p r e s s u r e t r a n s d u c e r mounted  121  Chewing monitor " s i l i c o n c h i p " p r e s s u r e mounted i n i t s s t e e l h o u s i n g  122  transducer  P l o t o f observed v a l u e s and p r e d i c t e d r e g r e s s i o n l i n e s (Y = a + blogX) f o r the r e l a t i o n s h i p between the times animals spent i d l e and chewing p e r kg i n t a k e (Y) and the median p a r t i c l e l e n g t h o f a timothy-bromegrass hay chopped t o 4 median p a r t i c l e l e n g t h s (X) when the hay was f e d i n a 60% f o r a g e , 40% concentrate r a t i o n  136  P l o t o f observed v a l u e s and p r e d i c t e d r e g r e s s i o n l i n e (Y = a + blogX) f o r the r e l a t i o n s h i p between the number o f b o l i r e g u r g i t a t e d d u r i n g r u m i n a t i o n p e r kg of i n t a k e (Y) and median f o r a g e p a r t i c l e l e n g t h ( X ) , and the e f f e c t o f median p a r t i c l e l e n g t h on time spent chewing p e r b o l u s r e g u r g i t a t e d when timothy-bromegrass hay was chopped t o 4 median p a r t i c l e l e n g t h s and f e d i n a 60% f o r a g e , 40% concentrate r a t i o n  137  ix  ACKNOWLEDGEMENT  F i r s t and Dr. J . A.  foremost  the author  S h e l f o r d f o r g i v i n g him  i s deeply  g r a t e f u l and  the o p p o r t u n i t y to pursue the  d e s c r i b e d h e r e i n , f o r h i s much t e s t e d p a t i e n c e , and guidance, and  f i n a n c i a l a s s i s t a n c e he has  s u p e r v i s i o n of t h i s  Galzy  f o r the  to  research  support,  g i v e n to the author  during  the  thesis.  S p e c i a l acknowledgement and exhaustive  indebted  thanks i s g i v e n to Maciek Kowalski  a s s i s t a n c e d u r i n g the r u n n i n g o f the s t e e r t r i a l  and  for his  to G i l l e s  f o r the development and c o n s t r u c t i o n o f e l e c t r i c a l components t h a t  were r e q u i r e d to monitor chewing a c t i v i t y o f c a t t l e . The  author  i s a l s o g r a t e f u l to C h e r y l M c C o l l  a s s i s t a n c e d u r i n g the m o n i t o r i n g  and  of chewing b e h a v i o r  P a u l W i l l i n g , W i l l i a m ( B i l l ) S l a c k and a s s i s t e d i n the c a r e o f the animals,  S y l v i a Leung f o r t h e i r and  to Ted  Cathcart,  the s t a f f i n the D a i r y U n i t  r u n n i n g o f experiments and  who  procurement  of supplies. The  author  a l s o thanks the N a t u r a l S c i e n c e s and E n g i n e e r i n g  Council f o r personal f i n a n c i a l Finally,  moral  support.  s p e c i a l thanks to my  p a r t o f t h i s manuscript,  Research  w i f e , Helene, f o r her a s s i s t a n c e i n t y p i n g  f o r a s s i s t i n g w i t h experiments and,  support.  x  especially, for  GENERAL INTRODUCTION  A l a c k o f f i b r e i n the d i e t o f ruminants can l e a d to d i s o r d e r s such as f a t cow  syndrome, abomasal u l c e r s , a c i d o s i s , l i v e r abscesses,  abomasums, r u m e n i t i s , and  low  f a t content  cows (Sudweeks and E l y , 1979). To p r e v e n t Research C o u n c i l  displaced  i n the m i l k o f l a c t a t i n g d a i r y these  d i s o r d e r s , the  ( N a t i o n a l Research C o u n c i l , 1978)  has  National  recommended t h a t  d i e t s f e d to l a c t a t i n g d a i r y cows s h o u l d c o n t a i n a minimum o f 17% f i b e r . Research, however, has s i z e i n forages  otherwise  f i b e r , n e u t r a l detergent  shown t h a t e x c e s s i v e r e d u c t i o n o f p a r t i c l e  adequate i n "chemical f i b e r and  f i b e r " components (eg. crude  a c i d detergent  f i b e r ) can reduce or even  e l i m i n a t e the e f f e c t i v e n e s s o f the f i b e r i n p r e v e n t i n g above. For t h i s reason, g i v e n amount of l o n g hay feeding of forages  crude  the d i s o r d e r s  listed  J o r g e n s e n e t a l . (1978) recommended the f e e d i n g of a i n the r a t i o n s of d a i r y c a t t l e . However,  the  i n a l o n g form as a l a r g e p r o p o r t i o n o f the d i e t can have  an i n h i b i t o r y e f f e c t on v o l u n t a r y f e e d i n t a k e and,  t h e r e f o r e , can  decrease  productivity. The  p a r t i c l e s i z e o f f e e d s t u f f s , and  e s p e c i a l l y that of forages,  been shown t o have a d i r e c t e f f e c t on the d i g e s t i o n p r o c e s s  and  has  feed  u t i l i z a t i o n i n ruminants. F e e d s t u f f s e n t e r i n g the rumen are s u b j e c t e d m i c r o b i a l d i g e s t i o n , the p r o d u c t s w a l l s and  o f which are absorbed through the rumen  i n t e s t i n a l t r a c t . However, a v a r i a b l e p r o p o r t i o n o f a  f e e d s t u f f , p r e d o m i n a n t l y the f i b e r f r a c t i o n ,  given  i s e i t h e r i n d i g e s t i b l e or  s l o w l y d i g e s t e d i n the rumen. These u n d i g e s t e d  r e s i d u e s can o n l y l e a v e  rumen by passage through the r e t i c u l o - o m a s a l o r i f i c e . The undigested  to  passage o f  -1-  the  these  or i n d i g e s t i b l e r e s i d u e s from the rumen, however, i s l i m i t e d  the p h y s i c a l s i z e o f the p a r t i c l e s . T h i s r e s t r i c t i o n to passage  only  affects  by  rumen f i l l which, i n turn, has an i n h i b i t o r y e f f e c t on voluntary feed intake. The reduction of the p a r t i c l e size and the subsequent passage of the undigested residue from the rumen i s p r i m a r i l y f a c i l i t a t e d by chewing a c t i v i t y during eating and ruminating. Therefore the monitoring of chewing behavior has been used to study the e f f e c t of reducing the p a r t i c l e size of forage fed to ruminants on forage u t i l i z a t i o n and as a measure of the fibrousness of the feed. Research has shown that the reduction of the p a r t i c l e size of forages fed  to ruminants can have a d i r e c t e f f e c t on increasing voluntary feed  intake by increasing the rate of passage of undigested residues from the rumen. Even though the increased rate of passage usually r e s u l t s i n a concomitant decrease i n d i g e s t i b i l i t y an increased p r o d u c t i v i t y can be r e a l i z e d from higher intake l e v e l s . Unfortunately, the incremental e f f e c t of a decrease i n forage p a r t i c l e size on increasing intake and rate of passage i s not consistent over the f u l l range of applicable p a r t i c l e sizes and between forage types. There appears to be no difference i n u t i l i z a t i o n between most forages fed i n a long or coarsely chopped form. Fine chopping and coarse grinding of more fibrous or mature forages w i l l usually enhance voluntary feed intake, whereas l i t t l e e f f e c t may  be seen when feeding s i m i l a r l y processed good  q u a l i t y forages. Fine grinding of most forages, however, w i l l generally r e s u l t i n the disappearance of normal rumination behavior and an increase i n the incidence of n u t r i t i o n a l disorders. Therefore, there appears to be a r e l a t i o n s h i p between the chemical  fiber  content and the p a r t i c l e size of feedstuffs fed to ruminants i n providing a minimum l e v e l of "physical f i b e r " s u f f i c i e n t to prevent digestive disorders but not l i m i t intake and productivity. Whereas the surface area of feedstuff  -2-  p a r t i c l e s may  have a d i r e c t e f f e c t on m i c r o b i a l d i g e s t i o n , i t i s l i k e l y  the passage o f p a r t i c l e s from the rumen i s u l t i m a t e l y l i m i t e d by  that  the l a r g e s t  dimension o f the p a r t i c l e s . Consequently, i t would be b e n e f i c i a l to q u a n t i f y the 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 on i n t a k e and  d i g e s t i o n to be  able  to  maximize f o r a g e u t i l i z a t i o n and p r o d u c t i v i t y . T h i s n a t u r a l l y n e c e s s i t a t e s the a c c u r a t e  q u a n t i f i c a t i o n o f the p a r t i c l e l e n g t h d i s t r i b u t i o n i n  processed  f o r a g e ; u n f o r t u n a t e l y , s t a n d a r d methods have not y e t been developed. The  research presented  i n t h i s t h e s i s was  t h e r e f o r e u n d e r t a k e n to  develop a method f o r q u a n t i f y i n g the p a r t i c l e l e n g t h d i s t r i b u t i o n processed  forage,  and  to determine the r e l a t i o n s h i p between the median  p a r t i c l e l e n g t h o f a f o r a g e and behavior  of  o f d a i r y c a t t l e . The  the v o l u n t a r y f e e d i n t a k e and  research project consisted of  experiments, the r e s u l t s o f which are p r e s e n t e d  chewing  five  i n the f o l l o w i n g t h r e e  chapters. Chapter 1 d e s c r i b e s the development and a c c u r a t e method f o r the a n a l y s i s and  t e s t i n g of a repeatable  d e s c r i p t i o n o f the p a r t i c l e  d i s t r i b u t i o n i n chopped f o r a g e . Chapter 2 r e p o r t s the r e s u l t s o f experiment to i n v e s t i g a t e the e f f e c t o f p r o c e s s i n g method and on the p a r t i c l e f o r a g e . The  the p r e p a r a t i o n o f d i e t a r y treatments o f p r o c e s s e d forages, processed  by  hammermilled  to determine i f , i n  forage,  Finally,  species  different similar  Chapter 3 r e p o r t s  the  experiments which i n v e s t i g a t e d the r e l a t i o n s h i p between the  median p a r t i c l e l e n g t h o f f o r a g e and behavior  an  the same method, r e s u l t e d i n the p r o d u c t i o n o f  p a r t i c l e l e n g t h and n u t r i e n t d i s t r i b u t i o n s . r e s u l t s o f two  length  forage  l e n g t h and n u t r i e n t d i s t r i b u t i o n o f chopped and  o b j e c t i v e o f t h i s p a r t o f the p r o j e c t was  and  o f d a i r y c a t t l e . The  automatic monitoring  the v o l u n t a r y f e e d i n t a k e and  development o f equipment, and  o f chewing a c t i v i t y are a l s o d e s c r i b e d .  -3-  chewing  a method f o r the  CHAPTER I  DESCRIPTION OF THE PARTICLE LENGTH DISTRIBUTION OF CHOPPED FORAGE USING A SIMPLE VIBRATING TRAY FORAGE PARTICLE SEPARATOR AND A MODIFIED WEIBULL-TYPE FUNCTION  INTRODUCTION  The  e f f e c t o f p a r t i c l e s i z e r e d u c t i o n i n f o r a g e s f e d to ruminants  parameters o f d i g e s t i o n  including  and  rate  the  e f f e c t o f f o r a g e p a r t i c l e s i z e on  d i d not o f the  o f passage i s w e l l  intake, d i g e s t i b i l i t y ,  involve  quantitative  forage. T r a d i t i o n a l  difference To be  the  documented. U n t i l r e c e n t l y ,  between the  the  analysis  chewing b e h a v i o r , the  investigation  i n ruminants  o f the  distribution  particle size  examined the  e f f e c t s o f f e e d i n g l o n g , chopped and e f f e c t s o f r e d u c i n g the  f o r a g e s i t i s n e c e s s a r y to have an o b j e c t i v e  qualitative ground f o r a g e s .  particle size  method f o r the  of  accurate  measurement o f p a r t i c l e s i z e . P a r t i c l e s i z e , however, w i t h r e s p e c t to particles,  can  i n c l u d e a number o f parameters such as  b r e a d t h , diameter, c r o s s s e c t i o n a l methodology, f o r b o t h the  a r e a , and  length, width,  volume. None o f the  s e p a r a t i o n o f p a r t i c l e s and  forage  the  existing  description  of  r e s u l t i n g p a r t i c l e s i z e d i s t r i b u t i o n , appears to q u a n t i t a t e a s p e c i f i c parameter when a p p l i e d The  s e l e c t i o n o f the  quantified  s h o u l d be  g r e a t e s t e f f e c t on rumen, the  the  the  size  separation of forage p a r t i c l e s .  a p p r o p r i a t e parameter or parameters to  based on  S i n c e i t appears t h a t  from the  to the  of  process of d i g e s t i o n  e x p e r i m e n t a t i o n has  a b l e to q u a n t i t a t e the  on  their relationship  to b i o l o g i c a l  maximum dimension o f a p a r t i c l e may  f o r a g e u t i l i z a t i o n by  l i m i t i n g the  development o f a method f o r the  -4-  be function.  exert  passage o f  quantitation  the  particles of  forage  p a r t i c l e l e n g t h , d e f i n e d as the maximum p a r t i c l e d i m e n s i o n , would be most appropriate. Therefore,  the p r e s e n t  s t u d y was  u n d e r t a k e n w i t h the  following  objectives:  1)  t o d e s i g n and c o n s t r u c t a v i b r a t i n g  tray forage p a r t i c l e  and t e s t i t s a c c u r a c y and p r e c i s i o n  i n s e p a r a t i n g chopped  particles  2)  on the b a s i s o f p a r t i c l e  to mathematically  separator forage  length,  d e f i n e the d i s t r i b u t i o n o f p a r t i c l e l e n g t h s  chopped f o r a g e ,  3)  and t o i d e n t i f y s t a t i s t i c a l parameters w h i c h would a d e q u a t e l y d e s c r i b e the p a r t i c l e l e n g t h d i s t r i b u t i o n s forages.  -5-  f o u n d i n chopped  in  LITERATURE REVIEW  MEASUREMENT OF FEEDSTUFF PARTICLE SIZE  Visual  Separation  A number o f methods have been used t o s e p a r a t e and p r o c e s s e d  forages  i n t o component p a r t i c l e  samples o f c o n c e n t r a t e s  s i z e f r a c t i o n s . The s i m p l e s t  and most a c c u r a t e method o f p a r t i c l e s i z e a n a l y s i s i s v i s u a l s e p a r a t i o n . I f p a r t i c l e s a r e s u f f i c i e n t l y l a r g e enough, a l l dimensions o f t h e p a r t i c l e s can be measured u s i n g a r u l e r o r a s e t o f c a l i p e r s . Measurement o f v e r y particles,  such as those  small  i n f e c e s o r f i n e l y ground f e e d s t u f f s , may r e q u i r e  the use o f a microscope, u s u a l l y f i t t e d w i t h c r o s s - h a i r s and a graduated scale  (Moseley, 1984). From the data t h a t a r e c o l l e c t e d ,  the frequency  d i s t r i b u t i o n o f any measured p a r t i c l e s i z e parameter c a n be determined and then charac-  t e r i z e d . Furthermore, d u r i n g v i s u a l s e p a r a t i o n , measured p i e c e s  o f f e e d s t u f f can be c o l l e c t e d i n s m a l l c o n t a i n e r s which c a n then be weighed to determine t h e weight d i s t r i b u t i o n o f the p a r t i c l e s i z e s i n a g i v e n sample. A major disadvantage o f v i s u a l s e p a r a t i o n , however, i s t h a t i t i s v e r y time consuming and t e d i o u s , and s u b j e c t t o l a r g e subsampling e r r o r s ; a one  kilogram  sample o f chopped forage may c o n t a i n i n excess o f 500,000  p i e c e s which p r o h i b i t s t h e e x a m i n a t i o n o f a l l b u t the s m a l l e s t subsamples (O'Dogherty, 1982). T h e r e f o r e , usually  t h e use o f some form o f automated method i s  required.  Sieving Both wet s i e v i n g and d r y s i e v i n g techniques the p a r t i c l e  have been used t o measure  s i z e d i s t r i b u t i o n o f f e e d s t u f f s . Dry s i e v i n g employs a s t a c k e d  -6-  s e r i e s o f s c r e e n s h a v i n g d i f f e r e n t a p e r t u r e s which decrease  i n s i z e from the  top t o the bottom o f the s t a c k . A r e p r e s e n t a t i v e sample i s p l a c e d on the top s i e v e and a g i t a t i o n o f the s i e v e s t a c k causes  s o r t i n g o f p a r t i c l e s i z e s by  the l i m i t a t i o n o f passage through each p r o g r e s s i v e s c r e e n i n r e l a t i o n t o p a r t i c l e s i z e . Wet s i e v i n g i s s i m i l a r t o d r y s i e v i n g except t h a t a stream or spray o f s o l v e n t ( u s u a l l y water) i s added t o wash the p a r t i c l e s  through the  stack of sieves. Standard  s i e v i n g methods, developed p r i m a r i l y f o r use i n the c h e m i c a l  and m i n e r a l r e l a t e d f i e l d s , have been adopted A g r i c u l t u r a l Engineers  (ASAE) (American  by the American S o c i e t y o f  Society of A g r i c u l t u r a l  1969a, 1983), the American S o c i e t y o f Animal S c i e n c e  (ASAS)  Engineers,  (American  S o c i e t y o f Animal S c i e n c e , 1969) and the American S o c i e t y o f D a i r y S c i e n c e (Ensor e t a l . . comprised  1970) f o r the measurement o f p a r t i c l e s i z e i n f e e d s t u f f s  o f s p h e r o i d a l o r c u b o i d a l shaped p a r t i c l e s as found i n  c o n c e n t r a t e s . When s i e v i n g s p h e r o i d a l p a r t i c l e s , r e t a i n e d on a g i v e n s i e v e i s determined a p e r t u r e and t h e diameter  the range o f p a r t i c l e  by the maximum diameter  sizes  o f the s i e v e  o f t h e s i e v e a p e r t u r e d i r e c t l y above. Even though  s i e v i n g has been d e s c r i b e d by the d e v e l o p e r s o f s i e v i n g methodology f o r s p h e r o i d a l p a r t i c l e s as b e i n g i n a p p r o p r i a t e f o r the " s i z i n g " o f e l o n g a t e d particles  (American  S o c i e t y o f A g r i c u l t u r a l E n g i n e e r s , 1983), r e s e a r c h e r s  have e x t e n s i v e l y used these t e c h n i q u e s f o r p a r t i c l e s i z e measurement i n chopped and ground f e e d s t u f f s , rumen samples, duodenal samples and f e c a l samples. The p a r t i c l e s predominantly  elongated  i n these substances, however, have been shown t o be (Mosely,  1984; McLeod e t a l . .  1984).  The major problem w i t h the s i e v i n g o f e l o n g a t e d p a r t i c l e s  i s t h a t the  s i z e parameter which c o n t r o l s the s e p a r a t i o n p r o c e s s has n o t been e l u c i d a t e d . Uden and Van Soest  fully  (1982) found t h a t a l a r g e r mean p a r t i c l e  -7-  size  was  o b t a i n e d from wet  p a r t i c l e s are  free  concluded that  dry  sieving  than was  to bounce around d u r i n g dry  from sheep f e d hay  v i s u a l l y measured the sieve. the  the  two  actual  sieve,  s i z e o f the  f o r a g e s i n the  each s i e v e . f i v e to one. s i z e o f the  The  and  clover  l e n g t h and  w h i l e the w i d t h o f the  dimensions o f the  to 28  c o e f f i c i e n t of v a r i a t i o n  on  f o r the  each than  the  i t may  be  between on  feedstuff useful,  the  that  by  sieving,  about  with  was  visually  into p a r t i c l e  wet  1/2  p a r t i c l e s was  p a r t i c l e w i d t h to a p e r t u r e  p e r c e n t . S i n c e the  f o r the  length  the for  v a l u e s and  size  range o f  the  r a t i o o f w i d t h to a p e r t u r e s i z e were t h e i r wet  s i e v i n g method  was  the b a s i s o f p a r t i c l e width,  w i d t h to a p e r t u r e s i z e r a t i o s , however, were always  T h e r e f o r e , i t i s s t i l l u n c l e a r as  being quantified  a difference  each s i e v e v a r i e d  following  s e p a r a t i n g f o r a g e p a r t i c l e s p r e d o m i n a n t l y on  than one.  on  p a r t i c l e l e n g t h to a p e r t u r e s i z e r a t i o s  researchers concluded that  l e n g t h . The  then  d i f f e r e n t s i e v e s w i t h d i f f e r e n t f o r a g e s ranged from  p e r c e n t , whereas t h a t  r a t i o s ranged from 19  not  also  to c o n v e r t s i e v e f r a c t i o n s  f o r the  and  p a r t i c l e s were about  s i e v e a p e r t u r e s t h a t were b e i n g used and  p a r t i c l e s c o l l e c t e d on  and  sieving  p a r t i c l e s t h a t were r e t a i n e d  p a r t i c l e sizes retained  c o e f f i c i e n t of v a r i a t i o n  sieving  were about 3 to 4 times l a r g e r  f r a c t i o n s . McLeod e t a l . (1984) found t h a t  s m a l l e r , the  researchers  s i e v e d rumen p a r t i c l e s  average l e n g t h to w i d t h r a t i o o f a l l the  S i n c e the  Since  width of p a r t i c l e s r e t a i n e d  s i e v e a p e r t u r e . There was  separating sieve fractions,  to 41  the  d i e t s u s i n g wet  b e i n g s e p a r a t e d , Moseley (1984) suggested t h a t  20  sieving.  sieving,  Mosely (1977) wet  lengths of p a r t i c l e s retained  a p e r t u r e o f the  to 3/4 the  The  dry  s i e v i n g m a i n l y measured diameter w h i l e wet  measured p a r t i c l e l e n g t h . Jones and collected  o b t a i n e d by  to which s i z e p a r a m e t e r ( s ) i s  when e l o n g a t e d p a r t i c l e s are  -8-  less  s e p a r a t e d by  sieving.  V i b r a t i n g Tray Separators V i b r a t i n g t r a y s e p a r a t o r s t h a t a r e capable o f measuring the p a r t i c l e length i n f e e d s t u f f s predominantly been developed  comprised  o f e l o n g a t e d p a r t i c l e s have  ( F i n n e r e t a l . . 1978; Gale and O'Dogherty, 1982). The  p r i n c i p l e o f the s e p a r a t i o n o f p a r t i c l e s on the b a s i s o f l e n g t h by these machines assumes t h a t the p a r t i c l e s e x h i b i t a l e n g t h t o w i d t h than 1:1, a r e l o n g i t u d i n a l l y symmetrical, weight r a t i o w i t h i n a p a r t i c l e .  r a t i o greater  and e x h i b i t a c o n s t a n t l e n g t h to  I f such a p a r t i c l e  i s conveyed h o r i z o n t a l l y  and l o n g i t u d i n a l l y over a gap, i n s t a b i l i t y occurs when the c e n t e r o f g r a v i t y o f the p a r t i c l e reaches particle results  the edge o f t h a t gap. F u r t h e r movement o f the  i n o v e r b a l a n c i n g and the p a r t i c l e f a l l s  through  T h e r e f o r e , e l o n g a t e d p a r t i c l e s p a s s i n g over a gap o f w i d t h X w i l l through  the gap i f the l e n g t h o f the p a r t i c l e  the gap. fall  i s 2X o r l e s s . I f p a r t i c l e s  are conveyed over a c a s c a d i n g s e r i e s o f gaps, s t a r t i n g a t the s m a l l e s t gap and p r o g r e s s i n g t o the l a r g e s t ,  the p a r t i c l e s c a n be s e p a r a t e d i n t o l e n g t h  f r a c t i o n s . The t h e o r e t i c a l l e n g t h o f p a r t i c l e s c o l l e c t e d below a g i v e n gap w i l l range from the maximum l e n g t h capable o f f a l l i n g immediately  through the  p r e c e d i n g gap t o twice the w i d t h o f the d e s i g n a t e d gap.  . M o l l e r (1975) d e s i g n e d forage p a r t i c l e s  such a s e p a r a t o r f o r measuring the l e n g t h o f  i n cobs and wafers.  s i n g l e c o r r u g a t e d sheet o f metal  1  M o l l e r s separator consisted o f a  on which p a r t i c l e s were l o n g i t u d i n a l l y  o r i e n t e d and e v e n l y d i s p e r s e d . An e c c e n t r i c , mounted on an e l e c t r i c motor, a g i t a t e d the c o r r u g a t e d sheet which was mounted on s p r i n g s t e e l s t r a p s . P a r t i c l e s were a u t o m a t i c a l l y a p p l i e d t o one end o f the c o r r u g a t e d sheet and p r o p e l l e d over a s e r i e s o f h o l e s o f i n c r e a s i n g diameter and  10 mm.)  each c h a n n e l  ( 1.4, 2, 4, 6, 8,  which had been d r i l l e d a t s e t i n t e r v a l s through i n the c o r r u g a t e d metal  the bottom o f  sheet. P a r t i c l e s l o n g e r than 20 mm i n  -9-  l e n g t h were s e p a r a t e d a t the end o f the t r a y by a s e r i e s o f t h r e e p l a t e s p l a c e d p e r p e n d i c u l a r to the bottom edge o f the c o r r u g a t e d sheet to produce gaps o f 15,  30 and 55  mm.  F i n n e r e t a l . (1978) developed p r i n c i p l e . The  a s e p a r a t o r which o p e r a t e d on the same  r e s e a r c h e r s , however, used a c a s c a d i n g s e r i e s o f c o r r u g a t e d  t r a y s s e p a r a t e d by p r o g r e s s i v e l y l a r g e r gaps. A l l the t r a y s were i n c l i n e d a t a 10 degree angle and were v i b r a t e d by an e l e c t r i c v i b r a t o r .  Forage  p a r t i c l e s were a p p l i e d by hand to the top s o r t i n g t r a y and were p r o p e l l e d by g r a v i t y over each o f the c o r r u g a t e d t r a y s . Each s u c c e s s i v e t r a y was 0.5  placed  times the gap w i d t h lower than the p r e v i o u s t r a y to enable  a smoother  passage o f p a r t i c l e s and a more e f f i c i e n t o v e r b a l a n c i n g o f the  particles.  Gale and O'Dogherty (1982) d e s i g n e d a unique  v i b r a t i n g tray separator  which a l s o used c o r r u g a t e d t r a y s b u t the s e p a r a t i o n p r o c e s s o p e r a t e d i n r e v e r s e t o those above w i t h l o n g e r p a r t i c l e s b e i n g s e p a r a t e d f i r s t ,  and  p r o g r e s s i v e l y s h o r t e r p a r t i c l e s b e i n g s e p a r a t e d as they t r a v e l l e d down the s e r i e s o f t r a y s . P a r t i c l e s were a p p l i e d to the f i r s t  t r a y by an  aspirator  column such t h a t s i n g l e p i e c e s o f f o r a g e were a p p l i e d and o r i e n t e d l o n g i t u d i n a l l y . A k n i f e edge p l a c e d a t a g i v e n d i s t a n c e p e r p e n d i c u l a r to the first  t r a y s e p a r a t e d the l o n g e s t p a r t i c l e s ;  r e q u i r e d to pass over the gap passed  through  a l l p a r t i c l e s s h o r t e r than t h a t the gap  on to the next  tray.  The next l o n g e s t p a r t i c l e s were then removed i n a s i m i l a r manner w i t h s h o r t e r p a r t i c l e s p a s s i n g t o the next t r a y and so on. The  the  s e p a r a t i o n o f the  l o n g e r p a r t i c l e s from the s h o r t e r p a r t i c l e s e l i m i n a t e d the c l o g g i n g and o t h e r s e p a r a t i o n problems f r e q u e n t l y encountered tray separators described previously.  -10-  w i t h the simple  vibrating  O s c i l l a t i n g Screen A modified al..  Separators  form o f s i e v i n g uses o s c i l l a t i n g s c r e e n s e p a r a t o r s  1978; F e l l e r and Foux, 1975). U n l i k e s i e v i n g which uses wire  o s c i l l a t i n g s c r e e n s e p a r a t o r s use l a r g e punched m e t a l screens apertures.  These screens  (Finner e t screens,  with l a r g e r  appear more s u i t a b l e f o r s e p a r a t i n g chopped  forages  where g r e a t e r numbers o f the p a r t i c l e s exceed 2 t o 3 cm. i n l e n g t h . However, the r e l a t i o n s h i p between s c r e e n s i z e and p a r t i c l e s i z e and the s i z e parameter b e i n g measured u s i n g o s c i l l a t i n g s c r e e n s e p a r a t o r s ,  as w i t h  s i e v i n g , has n o t been e l u c i d a t e d . F i n n e r e t a l . (1978) bypassed t h i s problem by measuring the p a r t i c l e l e n g t h o f p a r t i c l e s r e t a i n e d on each d i r e c t l y using o p t i c a l  screen  imaging.  O p t i c a l Imaging The al.  newest form o f p a r t i c l e s i z i n g i n v o l v e s o p t i c a l imaging. F i n n e r e t  (1978) d e s c r i b e d one system which used a H e w l e t t - P a c k a r d c a l c u l a t o r  p l o t t e r system and the U n i v e r s i t y o f W i s c o n s i n P a r t i c l e s o f f o r a g e s were c a r e f u l l y spread  U n i v a c 1110 computer.  over an X, Y g r i d on a h o r i z o n t a l  g l a s s s c r e e n such t h a t no p a r t i c l e s were t o u c h i n g endpoints  were i d e n t i f i e d w i t h  coordinates  each o t h e r .  Particle  the i n d i c a t o r arm o f a d i g i t i z e r and the  t r a n s m i t t e d t o the c a l c u l a t o r which determined and r e c o r d e d the  p a r t i c l e l e n g t h s . H a l l e t a l . (1970) used the USDA F l y i n g Spot  Particle  Analyzer  stems.  (FSPA) t o measure the c r o s s s e c t i o n a l a r e a o f a l f a l f a  Measurements were made by p h o t o g r a p h i n g c r o s s s e c t i o n a l views o f stem s e c t i o n s on 35 mm f i l m and measuring the r e s u l t i n g image areas u s i n g a f l y i n g s p o t f i l m scanner. L u g i n b u h l  on the FSPA  e t a l . (1984) photographed  samples o f p a r t i c l e s u s i n g a v i d e o camera and then d i g i t i z e d the image as a 256  x 256 a r r a y o f p o i n t s i n an Apple H e computer u s i n g an a p p r o p r i a t e  -11-  interface.  U s i n g the b i n a r y image, the  p a r t i c l e c o u l d be measured and  the  p e r i m e t e r , l e n g t h and  breadth of  p r o j e c t e d s u r f a c e a r e a o f the  each  particles  calculated. Optical analysis rapidly  imaging, once f u l l y developed, w i l l  o f p a r t i c l e s i z e which c o u l d be than u s i n g v i s u a l a n a l y s i s .  from l i m i t a t i o n s that  can  large  be  done more a c c u r a t e l y and  Optical  s i z e o f sample ( u s u a l l y  l e s s than 1000  efficiently  analyzed, n e c e s s i t a t i n g  either  numbers o f samples or the  the  suffers  particles)  analysis  of very  development o f e x t r e m e l y a c c u r a t e drawback to the  the weight d i s t r i b u t i o n o f p a r t i c l e s i z e s  DESCRIPTION OF  more  imaging, however, s t i l l  i n the  subsampling t e c h n i q u e s . A f u r t h e r that  a l l o w a more e x t e n s i v e  use  i s not  o f o p t i c a l imaging i s measurable.  PARTICLE LENGTH DISTRIBUTIONS  Frequency d a t a The  s i m p l e s t method f o r d e s c r i b i n g  the  p a r t i c l e s i z e d i s t r i b u t i o n of  a  substance i s to r e p o r t the p e r c e n t a g e o f p a r t i c l e s i n a sample h a v i n g a g i v e n s i z e or range o f s i z e s . A l t h o u g h the  reporting  o f the  p a r t i c l e l e n g t h d i s t r i b u t i o n i n t h i s manner p r o v i d e s the i n f o r m a t i o n r e g a r d i n g the  p a r t i c l e s i z e d i s t r i b u t i o n , and  recommended (Kennedy, 1984), i t does not  complete  most complete has  been  l e n d i t s e l f e a s i l y to  statistical  t e s t i n g and  communication between r e s e a r c h groups. A c o m p l i c a t i n g  exists  not  that  a l l r e s e a r c h e r s use  s i z e s , or gaps on  the  factor  same p a r t i c l e s i z i n g methods, s i e v e  f o r a g e p a r t i c l e s e p a r a t o r s , to s e p a r a t e f e e d s t u f f s  component p a r t i c l e s i z e f r a c t i o n s . that  the  Furthermore, t h e r e i s l i t t l e  e x p r e s s i o n of p a r t i c l e s i z e i n t h i s manner a i d s i n the  -12-  sample  into  evidence elucidation  o f the b i o l o g i c a l s i g n i f i c a n c e ruminant The  o f s p e c i f i c p a r t i c l e s i z e parameters  for  feedstuffs. quantitative  description  parameters o f d i g e s t i o n  o f the  i n ruminants n e c e s s i t a t e s  whole p a r t i c l e s i z e d i s t r i b u t i o n by of c e n t r a l  tendency and  e f f e c t of p a r t i c l e s i z e  one  or two  the  on  description  of  the  parameters (namely a measure  a measure o f spread) which w i l l be  independent  of  the method o f s e p a r a t i o n used.  Modulus o f F i n e n e s s and One  o f the  Uniformity:  e a r l i e s t methods f o r the  semi-quantitative description  p a r t i c l e s i z e d i s t r i b u t i o n o f ground f e e d s t u f f s o r i g i n a l l y d e v i s e d a t the U n i v e r s i t y ASAE as  procedure i n v o l v e s  the  dry  mesh p l u s the bottom pan)  s i m i l a r method o f s h a k i n g . The multiplying sieve the by  the  sizes  (3/8,  4,  8,  14,  Modulus o f F i n e n e s s i s c a l c u l a t e d  p e r c e n t weight o f the  sample r e t a i n e d  then d i v i d i n g by  100.  An  example o f the  the ASAE (1969b) recommendation, i s i l l u s t r a t e d  of  28,  by  depending upon how For  the m a t e r i a l  have the  same Modulus o f  i s d i s t r i b u t e d throughout the  t h i s r e a s o n the Modulus o f U n i f o r m i t y was  recommendation o f the ASAE as a d e s c r i p t o r s i z e d i s t r i b u t i o n (American S o c i e t y  i n t r o d u c e d as  o f the  two  Fineness  sieve  stack.  another  s p r e a d o f the  of A g r i c u l t u r a l Engineers,  -13-  given  I.  A major problem e x i s t s when u s i n g the Modulus o f F i n e n e s s i n t h a t c o m p l e t e l y d i f f e r e n t d i s t r i b u t i o n s may  the  summing  calculations,  i n Table  48,  other  on each s i e v e by  f o r the pan),  the  Engineers,  gram sample  f o r 5 minutes w i t h a r o - t a p or  p o s i t i o n number ( s t a r t i n g w i t h a v a l u e o f 0.0  r e s u l t s and  of A g r i c u l t u r a l  the  Fineness,  l a t e r adopted by  s i e v i n g o f a 250  ground f e e d through a s e t o f s t a n d a r d s i e v e 100  the Modulus o f  o f Wisconson and  a recommended procedure (American S o c i e t y  1969b). The  and  was  of  particle 1969b).  TABLE I : ASAE (1969b) example c a l c u l a t i o n s f o r t h e d e t e r m i n a t i o n the Modulus o f Fineness o f ground f e e d s t u f f s by s i e v i n g .  Screen Mesh  of  Product o f P e r c e n t o f M a t e r i a l on Screen Times the Screen P o s i t i o n  3/8 4 8 14 28 48 100 Pan  1.0 2.5 7.0 24.0 35.5 22.5 7.5 0.0  Total  x x x x x x x x  7 6 5 4 3 2 1 0  7.0 15.0 35.0 96.0 106.5 45.0 7.5 0.0  100.0  Modulus o f F i n e n e s s  312.0  (312.0 / 100.0)  The u n i f o r m i t y o f a sample i s e x p r e s s e d  =3.12  as the r a t i o o f t h r e e numbers which  r e p r e s e n t the r e l a t i v e p r o p o r t i o n s o f c o a r s e , medium and f i n e p a r t i c l e s i n the sample. The sum o f the f i g u r e s always must e q u a l 10 and the r a t i o s range from 10:0:0 t o 0:0:10 g i v i n g 66 p o s s i b l e combinations.  Particles  collected  on the 3/8, 4 and 8 mesh s i e v e s are d e s i g n a t e d as c o a r s e , 14 and 28 mesh as medium and 48 and 100 mesh p l u s the pan as f i n e p a r t i c l e s . The Modulus o f U n i f o r m i t y i s determined  by summing the percentage  weight o f p a r t i c l e s  c o l l e c t e d on the s i e v e s o f a g i v e n s i z e c a t e g o r y , d i v i d i n g the v a l u e by t e n and r o u n d i n g  to a whole number. An example g i v e n by the ASAE (1969b)  recommendation i s i l l u s t r a t e d i n T a b l e I I . The Modulus o f F i n e n e s s t o g e t h e r w i t h the Modulus o f U n i f o r m i t y adequately  d e s c r i b e d the p a r t i c l e s i z e d i s t r i b u t i o n o f ground f e e d s t u f f s i n  a s e m i - q u a n t i t a t i v e manner f o r p r e l i m i n a r y i n v e s t i g a t i o n o f the e f f e c t s o f f e e d s t u f f p a r t i c l e s i z e on ruminant  d i g e s t i o n . However,  these methods are  o n l y a p p l i c a b l e t o the s i e v i n g o f p r o c e s s e d f e e d s t u f f s where the p a r t i c l e s i z e r e d u c t i o n p r o c e s s y i e l d s s p h e r o i d a l or c u b o i d a l shaped p a r t i c l e s .  -14-  This  TABLE I I : ASAE (1969b) example c a l c u l a t i o n s f o r the d e t e r m i n a t i o n o f the Modulus o f U n i f o r m i t y o f ground f e e d s t u f f s by s i e v i n g .  Screen Mesh (A)  Percent of Sample on Screen (B)  T o t a l s i n Column (B) D i v i d e d by 10 (C)  3/8 4 8  COARSE 1.0 2.5 7.0  10.5  /  10 =  1.05  1  14 28  MEDIUM 24.0 35.5  59.5  /  10 =  5.95  6  FINE 22.5 7.5 0.0  30.0  /  10 -  3.00  3  48 100 Pan  Modulus o f U n i f o r m i t y  =  1:6:3  i s not the case w i t h the p r o c e s s i n g of f o r a g e s . set  of sieves is  sieve stack,  Column (C) Values Rounded (D)  Furthermore,if a  r e q u i r e d to e v e n l y d i s t r i b u t e the p a r t i c l e s  the r e s u l t i n g Modulus o f F i n e n e s s  comparable w i t h those v a l u e s  different  throughout  and U n i f o r m i t y v a l u e s  o b t a i n e d u s i n g the s t a n d a r d s e t  A measure s i m i l a r to the Modulus o f F i n e n e s s ,  of  sieves.  the p a r t i c l e  d i s t r i b u t i o n o f chopped forage which had been s e p a r a t e d i n t o f o u r  The  ( <25,  percentage  a weighting  25-50,  50-100,  are not  known as Chop Modulus  ( c i t e d by O'Dogherty, 1982), has been used to d e s c r i b e  fractions  and >100 mm) on a v i b r a t i n g t r a y  length  length separator.  weight o f the sample r e t a i n e d i n each t r a y was m u l t i p l i e d by  factor  (1,  2,  4,  or 8 r e s p e c t i v e l y ) .  The r e s u l t i n g v a l u e s  then summed and d i v i d e d by 100 to g i v e the Chop Modulus. U n f o r t u n a t e l y Chop Modulus s u f f e r s Fineness  the  were the  from the same l i m i t a t i o n as does the Modulus o f  i n that widely d i f f e r e n t p a r t i c l e length d i s t r i b u t i o n s  same Chop Modulus and t h a t the method i s  -15-  only semi-quantitative  can have  the  i n nature.  Mathematical D i s t r i b u t i o n Functions The of  i d e a l method f o r the d e s c r i p t i o n o f the p a r t i c l e s i z e  distribution  p r o c e s s e d f o r a g e i n v o l v e s the i d e n t i f i c a t i o n o f the u n d e r l y i n g  mathematical d i s t r i b u t i o n from which s t a n d a r d s t a t i s t i c a l parameters  such as  a mean, median and s t a n d a r d d e v i a t i o n ( o r o t h e r measure o f spread) c o u l d be c a l c u l a t e d . The m a j o r i t y o f the d i s t r i b u t i o n s o f p a r t i c l e s i z e s i n p r o c e s s e d f e e d s t u f f s are skewed t o the r i g h t . As e a r l y as 1925,  i t was  demonstrated  t h a t the p a r t i c l e s i z e s o f some comminuted substances c o u l d be d e s c r i b e d as being lognormally d i s t r i b u t e d Kolomogoroff(1941)  who  first  (Murphy and Bohrer, 1984). However, i t was advanced  a t h e o r e t i c a l e x p l a n a t i o n f o r the  l o g n o r m a l d i s t r i b u t i o n based on assumptions the of  lognormal d i s t r i b u t i o n ,  about comminution.  i n s t e a d o f the Modulus o f F i n e n e s s and Modulus  U n i f o r m i t y , f o r the d e s c r i p t i o n o f the p a r t i c l e s i z e d i s t r i b u t i o n i n  ground  feedstuffs  (see Headley and P f o s t , 1970)  Headley and P f o s t i n 1966  was  A g r i c u l t u r a l E n g i n e e r s , 1969a) and s t i l l  later  (American S o c i e t y o f  l a t e r as a s t a n d a r d procedure  (American S o c i e t y o f A g r i c u l t u r a l E n g i n e e r s , 1983) particle  f i r s t proposed by  (Murphy and Bohrer, 1984). The p r o c e d u r e was  adopted by the ASAE as a recommended procedure  the  The use o f  f o r the d e t e r m i n a t i o n o f  s i z e i n f e e d s t u f f s comprised o f s p h e r o i d a l o r c u b o i d a l  p a r t i c l e s . However, the procedure i s not recommended to d e f i n e the s i z e o f p a r t i c l e s which are f l a k e d or e l o n g a t e d such as are found i n r o l l e d or  grains  chopped f o r a g e . The s t a n d a r d procedure i n v o l v e s the use o f a s t a n d a r d s e t o f s i e v e  s t a r t i n g w i t h an a p e r t u r e o f 0.053 mm  and each a d d i t i o n a l s i e v e  sizes  getting  p r o g r e s s i v e l y l a r g e r i n a geometric p r o g r e s s i o n ( i e . the a p e r t u r e o f each a d d i t i o n a l s e i v e i s " r o o t 2" times the a p e r t u r e o f the p r e v i o u s s i e v e ) . S i e v i n g takes p l a c e on a s u i t a b l e s i e v e shaker and p r o g r e s s e s u n t i l t h e r e i s  -16-  a c o n s t a n t d i s t r i b u t i o n o f p a r t i c l e s between the s i e v e s . Based on the assumption  t h a t the p a r t i c l e s s i z e s a r e l o g n o r m a l l y d i s t r i b u t e d , the  f o l l o w i n g e q u a t i o n s can be used t o determine the geometric mean diameter and the geometric s t a n d a r d d e v i a t i o n .  where:  d ^  = log"  1  ( ( E C W i l o g d i ) / EWi))  S  = log'  1  g w  ((EWiClogdi - l o g d  d  g  Sg d^  w  W  g w  )  2  /  0  ZWi) -  5  = geometric mean diameter = geometric s t a n d a r d d e v i a t i o n = a p e r t u r e diameter o f the i ' t h s i e v e  d ^ ^ = a p e r t u r e diameter o f the s i e v e p l a c e d j u s t above the i ' t h s i e v e +  d£  =  geometric  on W£  =  the  weight  of  mean  diameter  i ' t h sieve material  of  particles  (d^ x di+i)^"^ on  the  i ' t h  G r a p h i c a l methods can a l s o be used t o determine  sieve  the geometric mean  diameter and s t a n d a r d d e v i a t i o n , and t o t e s t the goodness o f f i t o f the p a r t i c l e s i z e d i s t r i b u t i o n t o the lognormal d i s t r i b u t i o n .  I f a distribution  i s l o g n o r m a l l y d i s t r i b u t e d , p l o t t i n g the c u m u l a t i v e p e r c e n t weight o f the sample r e t a i n e d on each s i e v e a g a i n s t the l o g a r i t h m o f the diameter o f the a p e r t u r e o f t h a t s i e v e on l o g a r i t h m i c p r o b a b i l i t y paper w i l l y i e l d a s t r a i g h t l i n e . A c l o s e f i t o f the d a t a p o i n t s t o a s t r a i g h t l i n e and a random d i s t r i b u t i o n o f r e s i d u a l s around the l i n e i n d i c a t e s a good f i t o f the d a t a t o the lognormal d i s t r i b u t i o n . line,  I f the d a t a a d e q u a t e l y f i t s  a straight  the geometric mean diameter c a n be r e a d from the graph as the  geometric diameter a t the 50% p r o b a b i l i t y p o i n t and the geometric s t a n d a r d d e v i a t i o n c a l c u l a t e d as the geometric diameter a t the 84% p r o b a b i l i t y  -17-  point  d i v i d e d by the the geometric mean diameter. The geometric s t a n d a r d d e v i a t i o n can a l s o be c a l c u l a t e d by d i v i d i n g the geometric mean diameter by the geometric diameter a t the 16% p r o b a b i l i t y  point.  Another method o f c a l c u l a t i n g the geometric mean diameter and s t a n d a r d d e v i a t i o n was p r e s e n t e d by Waldo e t a l . (1971). The d i s t r i b u t i o n o f p a r t i c l e s i z e s was e x p r e s s e d as the c u m u l a t i v e p e r c e n t o f p a r t i c l e s by weight p a s s i n g through a s i e v e a p e r t u r e o f s i z e X ( i n m i c r o n s ) . The p e r c e n t weight o f the sample c a p a b l e p a s s i n g through each s i e v e was t r a n s f o r m e d t o normal e q u i v a l e n t d e v i a t e s (Y) and r e g r e s s e d on the base t e n l o g a r i t h i m o f the sieve aperture size normal  x  (X) u s i n g the e q u a t i o n Y = a + b l o g ^ g -  l  n  standardized  form Y = (logX - logu) / logS = (-logu / logS) + 1/logS x logX  where l o g u i s the geometric mean diameter and logS i s the geometric s t a n d a r d d e v i a t i o n . The geometric mean diameter c o u l d t h e r e f o r e be e s t i m a t e d by -a/b and the geometric s t a n d a r d d e v i a t i o n by 1/b. The b e n e f i t o f u s i n g the lognormal d i s t r i b u t i o n i s t h a t the p a r t i c l e s i z e d i s t r i b u t i o n c a n be d e s c r i b e d c o m p l e t e l y by two parameters, the geometric mean diameter and the geometric s t a n d a r d d e v i a t i o n .  Furthermore,  once the geometric mean diameter and s t a n d a r d d e v i a t i o n s by weight a r e known, the d i s t r i b u t i o n s o f p a r t i c l e numbers and s u r f a c e a r e a o f s p h e r o i d a l and c u b o i d a l shaped p a r t i c l e s c a n a l s o be d e s c r i b e d , and a l l t h r e e d i s t r i b u t i o n s w i l l have the same geometric s t a n d a r d d e v i a t i o n (Headley and Pfost,  1970).  Whereas the lognormal d i s t r i b u t i o n methods d e s c r i b e d above a r e o n l y a p p l i c a b l e f o r the d e s c r i p t i o n o f the p a r t i c l e s p h e r o i d a l and c u b o i d a l p a r t i c l e s ,  size d i s t r i b u t i o n of sieved  s i m i l a r procedures can be used i f  -18-  p a r t i c l e l e n g t h i s measured on a v i b r a t i n g t r a y s e p a r a t o r  (0'Dogherty,1984).  Where a p p l i c a b l e i n each a n a l y t i c a l procedure above, t h e s i e v e diameter i s r e p l a c e d by the minimum o r maximum t h e o r e t i c a l p a r t i c l e l e n g t h capable o f falling will Any  through each gap on the s e p a r a t o r . The r e s u l t s o f the c a l c u l a t i o n s  then y i e l d the geometric  mean p a r t i c l e  l e n g t h and s t a n d a r d d e v i a t i o n .  subsequent c a l c u l a t i o n s o f the d i s t r i b u t i o n o f p a r t i c l e numbers and  s u r f a c e a r e a a r e , however, no l o n g e r  valid.  Other d i s t r i b u t i o n s which have been f i t t e d  to p a r t i c l e size  data  o b t a i n e d from the s i e v i n g o f f e e d s t u f f s i n c l u d e the Gamma p r o b a b i l i t y d e n s i t y f u n c t i o n and the Rosin-Rammler o r W e i b u l l f u n c t i o n . These a r e e x p o n e n t i a l f u n c t i o n s which e x h i b i t g r e a t f l e x i b i l i t y when f i t t e d t o p r o b a b i l i t y d e n s i t y f u n c t i o n s o r s i g m o i d a l shaped c u m u l a t i v e d i s t r i b u t i o n s o f p a r t i c l e s i z e s such as a r e found and o t h e r  frequency  i n processed f e e d s t u f f s  substances.  E x p o n e n t i a l d i s t r i b u t i o n s such as the W e i b u l l f u n c t i o n are f i t t e d d a t a u s i n g n o n - l i n e a r r e g r e s s i o n o f the p e r c e n t cumulative on s i e v e s i z e ,  weight  distribution  i s c a l c u l a t e d by s o l v i n g the r e g r e s s i o n e q u a t i o n f o r t h e cumulative e q u a l t o 50%.  been put forward  Unfortunately,  computational  procedures  percent  have n o t  f o r a measure o f the spread o f the d i s t r i b u t i o n . The Gamma  p r o b a b i l t i t y d e n s i t y f u n c t i o n , though h i g h l y f l e x i b l e , gamma f u n c t i o n which makes the p a r a m e t e r i z i n g p r o c e s s formidable  undersize  o r p a r t i c l e l e n g t h as determined by v i b r a t i n g t r a y  s e p a r a t o r s . The median p a r t i c l e s i z e o r p a r t i c l e l e n g t h o f the  undersize  t o the  involves a recursive computationally  (Yang e t a l . . 1978). A l l e n e t a l . (1984), however, f i t the Gamma  p r o b a b i l i t y d e n s i t y f u n c t i o n u s i n g a procedure i n v o l v i n g maximum l i k l i h o o d estimators  f o r the parameters i n the f u n c t i o n .  Herdan (1960) recommended the use o f the Rosin-Rammler (or W e i b u l l )  -19-  f u n c t i o n when the the  d i s t r i b u t i o n of p a r t i c l e sizes  p o i n t t h a t the  d e v i a t e d from n o r m a l i t y  lognormal d i s t r i b u t i o n c o u l d not  be  to  adequately f i t t e d  to  s e p a r a t i o n d a t a . Furthermore, Rose (1954) demonstrated t h a t f o r  an  exponential d i s t r i b u t i o n ,  a number  or  shape or d e n s i t y  of  weight b a s i s was the  the  d i s t r i b u t i o n of p a r t i c l e s i z e s  independent o f the  sample s i z e and  p a r t i c l e s b e i n g s e p a r a t e d . T h e r e f o r e , the  use  the  o f an  on  exponential  d i s t r i b u t i o n to d e s c r i b e the weight d i s t r i b u t i o n o f p r o c e s s e d p a r t i c l e s by  sieving  does not  geometry or d e n s i t y as  r e q u i r e any  i t does when the  feedstuff  assumptions r e g a r d i n g  lognormal d i s t r i b u t i o n  particle i s used  (Pond e t a l . . 1984). S i n c e the p a r t i c l e has  s i z e parameter t h a t i s measured by not  i s v a l i d f o r the sieving.  y e t been e l u c i d a t e d , none o f the  sieving  fistulas,  measurement o f p a r t i c l e s i z e o f e l o n g a t e d p a r t i c l e s  i n processed forages, boluses c o l l e c t e d  rumen c o n t e n t s , duodenal d i g e s t a , and  some v a l i d i t y are  i f the  s i m p l y e x p r e s s e d as  the  sieving  goodness o f f i t o f the of feedstuffs  have  i m p l i e d and capable  the  of  (Kennedy, 1984).  comprised o f e l o n g a t e d p a r t i c l e s has  results  been  d i s t r i b u t i o n of p a r t i c l e sizes  i n chopped and  s i g n i f i c a n t l y d i f f e r e d from lognormal. The  pelleted  the  the that  orchardgrass  the  hay  r e s e a r c h e r s c o n c l u d e d , however,  adequate f o r many p r a c t i c a l and  -20-  adequate, but  of  variable.  assumption o f l o g n o r m a l i t y f o r  i n f e c a l samples was  f i t was  p r o c e d u r e s do  percentage of p a r t i c l e s  d i s t r i b u t i o n of p a r t i c l e s i z e s  t h a t the  description  f e c a l samples, a l l o f which  lognormal d i s t r i b u t i o n to the  Waldo e t a l . (1971) found t h a t the  by  through esophageal  measurement o f a s i z e parameter i s not  p a s s i n g a given s i z e of sieve aperture The  elongated  p r o c e d u r e s d e s c r i b e d above  p r e d o m i n a n t l y comprised o f e l o n g a t e d p a r t i c l e s . The  results  of  However, r e s e a r c h e r s have used these p r o c e d u r e s f o r the  of p a r t i c l e s i z e  are  the  s c i e n t i f i c purposes.  Allen  e t a l . (1984) a l s o  found a s i g n i f i c a n t l a c k o f f i t o f s e p a r a t i o n d a t a to  lognormal d i s t r i b u t i o n when the and  f e c a l samples was  b e t t e r f i t was fitted  to the  p a r t i c l e s i z e d i s t r i b u t i o n o f ground f o r a g e s  examined by  o b t a i n e d when the d a t a by  the  procedure o f Waldo e t a l . (1971). A  lognormal p r o b a b i l i t y  standard deviation: t h i s i s s i m i l a r  o b t a i n e d u s i n g the  The  best o v e r a l l  Gamma p r o b a b i l i t y  esophagus, upper and  t h e n f i t the  lower rumen s t r a t a ,  p a r t i c l e d i s t r i b u t i o n d a t a to the  e x p o n e n t i a l d i s t r i b u t i o n based on function.  The  of a l l the and  samples because the  closely  f i t the  o b s e r v e d d a t a and  a p p r o p r i a t e i n d e s c r i b i n g the  the  function.  Bermuda g r a s s taken  feces of c a t t l e ,  and  use  o f the  an  Weibull  lognormal  particle size  distribution  f i t t e d curves e x h i b i t e d s i g n i f i c a n t  c o n c l u d e d t h a t the  the  lognormal d i s t r i b u t i o n and  i n a p p r o p r i a t e f o r d e s c r i b i n g the  skewness. They a l s o  the  f i t t i n g of  density  a m o d i f i e d Rosin-Rammler or  r e s e a r c h e r s c o n c l u d e d t h a t the  d i s t r i b u t i o n was  and  was  and  s t a n d a r d d e v i a t i o n d e s c r i b e d above u s i n g  Pond e t a l . (1984) s i e v e d samples o f g r a z e d c o a s t a l from the  l o g mean  to the method o f c a l c u l a t i n g  weights o f p a r t i c l e s r e t a i n e d on each s i e v e . d a t a , however, was  density function  maximum l i k e l i h o o d e s t i m a t o r s o f the  geometric mean diameter and  the  kurtosis  e x p o n e n t i a l d i s t r i b u t i o n more  t h a t i t s use  was  t h e r e f o r e more  p a r t i c l e s i z e d i s t r i b u t i o n i n samples  comprised o f e l o n g a t e d p a r t i c l e s . Smith e t a l . (1984) found t h a t when the  c e l l wall p a r t i c l e  d i s t r i b u t i o n o f d i g e s t a samples (procedure o f Smith and alfalfa, the  o r c h a r d g r a s s and  corn silage  e x p o n e n t i a l d i s t r i b u t i o n used by  advantages, and  d i d not  improve the  lognormal d i s t r i b u t i o n . The detergent s o l u t i o n  prior  f e d c a t t l e was  extraction  to s i e v i n g  Waldo, 1969)  determined by  Pond e t a l . (1983, 1984) f i t o f the o f the  may,  -21-  size  data, as  from sieving,  offered  compared to  no the  samples w i t h a n e u t r a l  however, have a l t e r e d  the  particle  size distributions comparison o f the distributions  on  o f the  samples. Furthermore, the  goodness o f f i t between the the  comparison o f the  d i s t r i b u t i o n of r e s i d u a l s , r e g r e s s i o n e q u a t i o n s . The r e g r e s s i o n of p r o b i t  and  on  sieve  dissimilar  performed by  linear  f i t t i n g o f the W e i b u l l f u n c t i o n  the  was  c u m u l a t i v e p e r c e n t weight u n d e r s i z e  size. Bohrer (1984) examined some t e n a b l e assumptions r e g a r d i n g  comminution o f e l o n g a t e d p a r t i c l e s which c o u l d l e a d Rosin-Rammler p a r t i c l e s i z e d i s t r i b u t i o n s . lead  determination,  t r a n s f o r m e d c u m u l a t i v e p e r c e n t weight u n d e r s i z e on  n o n l i n e a r r e g r e s s i o n o f the  Murphy and  not  of  their  Weibull  sums o f squares f o r two  lognormal r e g r e s s i o n was  l o g a r i t h m o f s i e v e s i z e , w h i l e the performed by  lognormal and  coefficients  residual  r e s e a r c h e r s based  to the  The  to the  lognormal  the  or  researchers' assumptiions  did  g e n e r a t i o n o f a lognormal d i s t r i b u t i o n . However, even  though they a d m i t t e d t h a t the r e s u l t s b e t t e r , Murphy and  Rossin-Rammler d i s t r i b u t i o n would f i t the  Bohrer (1984) c o n c l u d e d t h a t r e s o l v i n g  the  lognormal d i s t r i b u t i o n o f  i t s components would p r o v i d e more i n f o r m a t i o n than  would " g l o s s i n g "  differences  over the  d i s t r i b u t i o n w i t h the One  use  c o u l d argue t h a t the  d i s t r i b u t i o n t h a t d i d not error  use  o f any  correctly  the the  lognormal Rosin-Rammler.  parameters d e r i v e d from a mathematical f i t the  t h a t r e l y on  observed data c o u l d the  introduce  accurate q u a n t i f i c a t i o n  of  size.  Little the  d a t a and  o f another d i s t r i b u t i o n such as  into experimental r e s u l t s  particle  between the  information i s available  r e g a r d i n g the  mathematical d e f i n i t i o n  d i s t r i b u t i o n of p a r t i c l e lengths i n processed f e e d s t u f f s .  O'Dogherty (1982) found t h a t the f o r a g e s e p a r a t e d on  a vibrating  lognormal d i s t r i b u t i o n , but  Gale  p a r t i c l e length d i s t r i b u t i o n of tray  s e p a r a t o r c o u l d be  showed no  statistical  -22-  and  chopped  approximated by  testing  to prove  the  a  of  p o i n t . The g r a p h i c a l r e p r e s e n t a t i o n o f an observed p a r t i c l e d i s t r i b u t i o n , however,  exhibited a sinusoidal d i s t r i b u t i o n of residuals  around the r e g r e s s i o n l i n e . a l a c k o f f i t . O'Dogherty d i s t r i b u t i o n s diverged but c o n c l u d e d  length  Such a d i s t r i b u t i o n o f r e s i d u a l s would i n d i c a t e  (1984) found t h a t some o b s e r v e d p a r t i c l e  from l o g n o r m a l i t y i n the " t a i l s "  t h a t the d i s t r i b u t i o n s were,  o f the d i s t r i b u t i o n ,  i n g e n e r a l , an adequate  a p p r o x i m a t i o n o f a lognormal d i s t r i b u t i o n over much o f the p a r t i c l e range. No o t h e r examples o f the f i t t i n g  of p a r t i c l e length  determined u s i n g v i b r a t i n g t r a y s e p a r a t o r s , available.  length  length  distributions,  t o known d i s t r i b u t i o n s a r e  MATERIALS AND METHODS  SEPARATION OF FORAGE PARTICLES  A v i b r a t i n g t r a y Forage P a r t i c l e S e p a r a t o r (FPS) the  separation  was d e v e l o p e d t o enable  o f chopped f o r a g e p a r t i c l e s on the b a s i s  o f l e n g t h (see  Figure  1 ) ; i t s d e s i g n was based on the v i b r a t i n g t r a y s e p a r a t o r developed by  Finner  e t a l . (1978) . The FPS was comprised o f a t r a y bed,  b e d frame and  base frame. The  t r a y b e d was comprised o f a c a s c a d i n g s e r i e s o f seven c o r r u g a t e d  t r a y s made from enamel c o a t e d sheet s t e e l mounted on a t r a y frame made from 50.4  cm angle i r o n . The f i r s t  p a r t i c l e s , was 61 cm l o n g separation  tray,  followed  f o r the a p p l i c a t i o n and alignment o f by one 25 cm and then f i v e 20 cm l o n g  t r a y s , each measuring 76 cm i n w i d t h . The t r a y s were s e p a r a t e d by  gaps measuring 2, 2, 5, 10, 20, and 40 mm r e s p e c t i v e l y and each t r a y was p o s i t i o n e d  successive  one h a l f the gap s i z e lower than the p r e c e e d i n g  Two 2 mm gaps were used because the s m a l l e s t  length  tray.  f r a c t i o n comprised a  l a r g e p a r t o f the f o r a g e samples and was the most d i f f i c u l t  t o s e p a r a t e . The  c o r r u g a t e d t r a y s were s t r e n g t h e n e d and a l i g n e d by wood and metal supports which were a t t a c h e d t o the t r a y frame by 15 cm l o n g p i e c e s t h r e a d e d rod.  o f 12.7 mm  S l o t t e d h o l e s i n the t r a y frame and the use o f t h r e a d e d r o d  permitted unlimited  adjustment o f the t r a y s . The t r a y bed ( t r a y s p l u s  tray  frame) was b o l t e d a t a 13 degree angle t o the bed frame. The bed frame i n t u r n was b o l t e d  t o the f o u r c a n t i l e v e r supports o f the base frame. The bed  frame and base frame were b o t h c o n s t r u c t e d cm  from 7.62 cm c h a n n e l i r o n . A 2.54  pneumatic p i s t o n v i b r a t o r was mounted t o the f r o n t o f the bed frame. The  f r e q u e n c y and amplitude o f the v i b r a t i o n was a d j u s t e d by an a i r p r e s s u r e  -24-  regulator The  mounted on the base frame.  d e s i g n o f the s e p a r a t o r was such t h a t when the c o r r e c t v i b r a t i o n  f r e q u e n c y was a p p l i e d  t o the bed frame, i t would v i b r a t e h o r i z o n t a l l y a t the  n a t u r a l harmonic f r e q u e n c y o f the c a n t i l e v e r s u p p o r t s . T h i s v i b r a t i o n was transmitted  e v e n l y t o the s e p a r a t o r t r a y s by the mounting o f the t r a y bed t o  the bed frame and caused the f o r a g e p a r t i c l e s t o "flow" down the grooves i n the  t r a y s w i t h o u t b o u n c i n g o r jumping the gaps between t r a y s . During separation  the f o r a g e p a r t i c l e s were a p p l i e d by hand t o the top  a p p l i c a t i o n and alignment t r a y such t h a t t h e r e was no clumping o f p a r t i c l e s . P a r t i c l e s f a l l i n g through each gap were c o l l e c t e d below i n mounted p l e x i g l a s s c o l l e c t i o n t r a y s . The arrangement o f s e p a r a t i o n u s e d t h e o r e t i c a l l y r e s u l t e d i n the s e p a r a t i o n length  trays  o f the f o l l o w i n g  t h a t was  six particle  f r a c t i o n s a c c o r d i n g t o the " o v e r b a l a n c i n g p r i n c i p l e " : <4, 4-10,  10-20, 20-40, 40-80, and >80 mm.  Once a sample had been s e p a r a t e d , the  p a r t i c l e s c o l l e c t e d i n each o f the c o l l e c t i o n t r a y s were t r a n s f e r r e d t a r e d p l a s t i c bags and weighed. The r e s u l t s o f the s e p a r a t i o n as  the p e r c e n t o f sample weight, on an a i r d r y b a s i s ,  each o f the t h e o r e t i c a l p a r t i c l e l e n g t h  into  were e x p r e s s e d  t h a t was c o l l e c t e d i n  fractions.  FORAGE PARTICLE SEPARATOR TESTING  FPS  S e p a r a t i o n o f Hand Chopped A l f a l f a Hay A sample o f b a l e d  a l f a l f a hay was chopped by hand on a paper c u t t e r  t h a t a wide d i s t r i b u t i o n o f p a r t i c l e l e n g t h s was produced.  The chopped  a l f a l f a was then s u b d i v i d e d i n t o f o u r samples which comprised the t o t a l amount o f a l f a l f a chopped. Each subsample was s e p a r a t e d on the FPS i n t o  -26-  such  particle To  length  test  results, given  the  effect  method  were  length  fractions  which were  of  particle  subsample  shortest  was  the  fractions  then  fraction  resulting  performed  length  a  second  reseparated ending  on  the  with  the  were  resulting  reproducibility  c o l l e c t e d from consecutively,  reseparation  time  weighed.  separation  fractions  and  from  of  then  in  the  starting  longest.  The  then weighed.  three  separation with  separations  of  of  FPS a  the  particle This  of  length  reseparation each  subsample. The weight  effect  of  the  collected in  following University  General of  method  separation  each p a r t i c l e  Linear  British  length  Hypothesis  on  the  percent  f r a c t i o n was  using  the  t e s t e d by  BMD:10V  package  Y^j^  =  the dependent v a r i a b l e : percent subsample weight collected.  u  =  the  Fi  =  the e f f e c t of the i ' t h (ie. particle length  gap i n t h e fraction).  FPS  R^j  =  the  separation  run  +  u  ^  =  Eij^  i  F  +  Rij  +  overall  effect  s  =  e  i k  +  E  length  fraction,  fractions,  were  of  the  i j k  of  the  j ' t h  the  i'th  fraction.  e f f e c t o f the k' t h subsample nested w i t h i n the i ' t h fraction.  the r e s i d u a l e r r o r a s s o c i a t e d the i n t e r a c t i o n between the s e p a r a t i o n run and the k t h w i t h i n the i ' t h f r a c t i o n .  percent  between  weight  samples  tested using  of  mean.  1  the  the  program  =  S ^  in  subsample  Columbia:  nested within  Differences  of  i j k  Y  where:  of  and  of  sample  separation  Duncan's  Multiple  -27-  with j ' t h subsample  collected in runs Range  within test  each  particle  particle  ( a  =  length  0.05).  FPS v s . V i s u a l  S e p a r a t i o n o f Machine Chopped Orchardgrass  Hay  Three b a l e s o f mature o r c h a r d g r a s s hay were broken open and the b a l e sheaves randomly a l l o c a t e d a t random was 3.18,  6.35,  into  t h r e e p i l e s . Each p i l e o f sheaves,  then chopped a t one  o r 9.54  w i t h 6 B l a d e s . The  mm)  of three t h e o r e t i c a l  l e n g t h s o f c u t (TLC =  on a John Deere Model 35 Forage H a r v e s t e r  TLC was  changed by a l t e r i n g the i n f e e d  a c c o r d i n g to machine s p e c i f i c a t i o n s . of f o u r groups o f t h r e e subsampling  The  chopped hay was  boxes arranged  gear  blown i n t o  The  chopped f o r a g e c o n t a i n e d i n s i m i l a r l y numbered subsample boxes  After  to one  and then subsampled by q u a r t e r i n g i n t o a 50g  the p a r t i c l e l e n g t h f r a c t i o n s  an a r r a y  as shown i n F i g u r e 2.  from each o f the groups was  l i t r e volume) b e f o r e b e i n g s e p a r a t e d on the  fitted  ratios  box  composited  randomly a l l o c a t e d  selected  of three  samples. was  sample (approx  o f each sample were weighed,  similar  w i t h i n each sample o f a g i v e n TLC were composited  divided  subsamples. These subsamples were v i s u a l l y s e p a r a t e d  two  determine the a c t u a l  from 0-4  The  first  and 4-10  s e p a r a t e d i n 5 mm in  10 mm The  two  mm  fractions  respectively.  increments.  The  contained p a r t i c l e s Particles remaining  to  and  then  t h a t ranged i n l e n g t h  r a n g i n g from 10 to 80 mm l o n g e r p a r t i c l e s were  were  separated  increments. actual  p a r t i c l e l e n g t h d i s t r i b u t i o n f o r each p a r t i c l e  fraction collected determined  on the FPS was  calculated  by m u l t i p l y i n g  length  the v i s u a l l y  p e r c e n t weight o f a g i v e n range o f p a r t i c l e l e n g t h s i n the  f r a c t i o n by the weight o f a l l the p a r t i c l e s the FPS.  which were  then  length  The p a r t i c l e s were measured w i t h a r u l e r  s e p a r a t e d manually i n t o as many as 26 l e n g t h f r a c t i o n s weighed.  and  p a r t i c l e l e n g t h d i s t r i b u t i o n f o r each p a r t i c l e  f r a c t i o n w i t h i n a g i v e n TLC.  1.0  FPS.  length fractions into  The  actual  collected  i n that f r a c t i o n  p a r t i c l e l e n g t h d i s t r i b u t i o n f o r each TLC was  -28-  One  then  on  FIGURE 2: Arrangement o f 4 groups o f subsampling boxes f o r o b t a i n i n g 3 r e p r e s e n t a t i v e samples o f a chopped f o r a g e .  -29-  determined by  summing the v i s u a l l y determined p a r t i c l e l e n g t h  o f the p a r t i c l e l e n g t h f r a c t i o n s g i v e n TLC. a single  on the FPS.  comprising  Both the v i s u a l l y and  FPS  were a l s o u s e d to c a l c u l a t e  with  (Choi, 1978)  v i s u a l separation  determined u s i n g the FPS  consistency  o f p a r t i c l e s and on the FPS  was  o f FPS  o f p a r t i c l e s i n each p a r t i c l e l e n g t h  as a whole, were t e s t e d by  proportions oversizing  test  (Choi, 1978). The  and u n d e r s i z i n g by  The  FPS.  were compared  of  different  fraction  oversizing  and between TLC,  (Choi,  e r r o r by  the  for a l l particle  the C h i squared comparison o f s e v e r a l difference  the FPS  t h e o r e t i c a l p a r t i c l e length fractions  DESCRIPTION OF  that  the  t e s t e d u s i n g a C h i squared c o n t i n g e n c y t a b l e  between p a r t i c l e l e n g t h f r a c t i o n s  lengths  TLC  length  p a r t i c l e s i z i n g accuracy  1978) . D i f f e r e n c e s i n the degree o f u n d e r s i z i n g and FPS  data  the C h i squared goodness o f f i t t e s t  u s i n g the v i s u a l data as the expected p a r t i c l e  d i s t r i b u t i o n . The  collected  o f a i r dry sample weight  i n c o r r e c t l y c l a s s i f i e d on the b a s i s o f l e n g t h by  those determined v i s u a l l y by  lengths  length  the p e r c e n t a g e weight o f p a r t i c l e s i n each  p a r t i c l e length d i s t r i b u t i o n s  of  samples  i n each l e n g t h f r a c t i o n o f the sample c o l l e c t e d on the FPS,  c o r r e c t l y and The  i n the d e t e r m i n a t i o n  determined p a r t i c l e  a g i v e n range o f p a r t i c l e l e n g t h s . The  sample, and  samples o f a  p a r t i c l e l e n g t h d i s t r i b u t i o n f o r each s e t o f TLC  d i s t r i b u t i o n s were e x p r e s s e d as the p e r c e n t  was  from the  T h i s method o f v i s u a l s e p a r a t i o n r e s u l t e d  actual  separated  t h a t were c o l l e c t e d  distributions  was  between the degree o f  then used to c a l i b r a t e  t h a t were b e i n g  collected  the on the  FPS.  PARTICLE LENGTH DISTRIBUTIONS  v i s u a l and  FPS  s e p a r a t i o n data f o r chopped mature o r c h a r d g r a s s  d e s c r i b e d above were c o n v e r t e d  to the p e r c e n t  -30-  hay  c u m u l a t i v e weight o f sample  particles  t h a t were s h o r t e r than the maximum l e n g t h t h e o r e t i c a l l y  capable of  p a s s i n g through each gap on t h e FPS ( i e . P e r c e n t Cumulative Weight U n d e r s i z e ) . F o r a l l b u t the l a s t c o l l e c t i o n t r a y , t h e maximum l e n g t h o f p a r t i c l e c a p a b l e o f p a s s i n g through a g i v e n gap was determined from the c a l i b r a t i o n o f the FPS above. The maximum p a r t i c l e l e n g t h c o l l e c t e d  i n the  l a s t c o l l e c t i o n t r a y was determined by measuring the l o n g e s t p a r t i c l e i n the t h a t t r a y . The c u m u l a t i v e p e r c e n t weight o f p a r t i c l e s u n d e r s i z e (Y) was then r e g r e s s e d on p a r t i c l e l e n g t h (X) u s i n g each o f t h e f o l l o w i n g mathematical equations:  1: Y = a + bX 2: Y = a + b l o g X 3: logY = a + b l o g X 4: Y = a + b l o g X (Y i n s t a n d a r d p r o b a b i l i t y Waldo e t a l . . 1971)  units-  C -(BX) 5: Y = 100 x (1 - e ) (Modified Weibull or Rossin-Rammler type f u n c t i o n - Yang e t a l . . 1978)  E q u a t i o n s 1, 2, 3, and 4 were f i t t e d t o t h e d a t a by l i n e a r u s i n g t h e BMD:P1R packaged program  regression  o f the U n i v e r s i t y o f B r i t i s h Columbia.  The W e i b u l l f u n c t i o n ( e q u a t i o n 5) was f i t t e d t o the d a t a by n o n - l i n e a r r e g r e s s i o n u s i n g the BMD:PAR packaged program Columbia. The c o e f f i c i e n t s  o f the U n i v e r s i t y o f B r i t i s h  o f d e t e r m i n a t i o n and d i s t r i b u t i o n o f r e s i d u a l s  f o r each r e g r e s s i o n l i n e were compared t o determine goodness  o f f i t o f each  d a t a s e t t o t h e l i n e s p r e d i c t e d by each r e g r e s s i o n e q u a t i o n . R e g r e s s i o n e q u a t i o n s 2, 4 and 5 were used t o p r e d i c t t h e p e r c e n t weight o f sample p a r t i c l e s  t h a t were c o l l e c t e d  -31-  i n each p a r t i c l e l e n g t h f r a c t i o n on  the FPS.  To compare the goodness o f f i t between the r e g r e s s i o n  equations,  the p r e d i c t e d p a r t i c l e l e n g t h d i s t r i b u t i o n from each r e g r e s s i o n e q u a t i o n compared w i t h  the observed p a r t i c l e l e n g t h d i s t r i b u t i o n u s i n g  C h i squared goodness o f f i t t e s t The  median p a r t i c l e l e n g t h s  (the l e n g t h o f 50%  Cumulative Weight  s e p a r a t i o n d a t a were p r e d i c t e d u s i n g  e q u a t i o n s 2, 4 and  p r e d i c t e d median p a r t i c l e l e n g t h s  subjectively equations, visual  compared f o r a c c u r a c y  TLC  and  regression  were  c o n s i s t e n c y between r e g r e s s i o n  samples, and method o f s e p a r a t i o n ;  s e p a r a t i o n data d i d not p e r m i t s t a t i s t i c a l  i n the p r e d i c t e d median p a r t i c l e  the  ( A l l e n e t a l , 1984).  U n d e r s i z e ) f o r v i s u a l and 5. The  was  lengths.  -32-  lack of r e p l i c a t i o n testing  o f any  of  differences  RESULTS AND  OPERATION OF THE  The  DISCUSSION  FORAGE PARTICLE SEPARATOR  ease o f s e p a r a t i o n o f chopped f o r a g e p a r t i c l e s  from e f f o r t l e s s to v e r y d i f f i c u l t .  on the FPS  S i m i l a r s e p a r a t i o n problems t o  ranged those  d e s c r i b e d by F i n n e r e t a l . (1978) and Gale and O'Dogherty (1982) were encountered.  Ideally  shaped p a r t i c l e s  r e s e m b l i n g u n i f o r m rods  separated  e f f o r t l e s s l y as t h e o r i z e d . Chopped f o r a g e samples, however, c o n t a i n a v a r i a b l e p r o p o r t i o n o f i r r e g u l a r l y shaped p a r t i c l e s . and p a r t i c l e s  that lack structural  "U"  shaped  particles  r i g i d i t y c o u l d t h r e a d t h e i r way  through  gaps t h a t were s m a l l e r than those which they s h o u l d t h e o r e t i c a l l y have been able to f a l l  through.  "L" shaped p a r t i c l e s  and p a r t i c l e s w i t h rough edges  c o u l d get snagged i n gaps as they passed down the s e p a r a t o r . T h i s  snagging  would d r a m a t i c a l l y i n c r e a s e the time r e q u i r e d t o s e p a r a t e a sample by c a u s i n g the gaps to become c l o g g e d which, i n t u r n , caused a p p r o p r i a t e l y sized particles  to f l o w over the gap  t h a t they o t h e r w i s e would have f a l l e n  through. Because o f these s e p a r a t i o n problems, c o n s t a n t s u r v e i l l a n c e necessary through  was  to u n c l o g gaps between t r a y s . Most t r a p p e d p a r t i c l e s were pushed  the gap  they were c l o g g i n g w i t h the e x c e p t i o n o f o b v i o u s l y l o n g  p a r t i c l e s which were saved and r e o r i e n t e d to c o n t i n u e down the s e p a r a t o r . These major s e p a r a t i o n problems were s u c c e s s f u l l y a v o i d e d i n the machine d e s i g n e d by Gale & O'Dogherty (1982). However, the c o n s t r u c t i o n c o s t and complexity of design of that separator precluded a s i m i l a r  design i n this  study. Because the a l f a l f a hay  c o n t a i n e d more i r r e g u l a r i l y shaped p a r t i c l e s , i t  was  c o n s i s t e n t l y more d i f f i c u l t  to s e p a r a t e than was  With b o t h f o r a g e s , s h o r t e r p a r t i c l e s  tended to s e p a r a t e more e a s i l y than d i d  l o n g e r p a r t i c l e s because these p a r t i c l e s and more r i g i d .  the o r c h a r d g r a s s hay.  tended to be more i d e a l l y  shaped  T h e r e f o r e , o r c h a r d g r a s s hay chopped a t the s h o r t TLC  was  e a s i e r t o s e p a r a t e than t h a t chopped a t the l o n g TLC. S e p a r a t i o n times f o r all  samples  ranged from 15 minutes t o 2 hours w i t h the average time f o r  s e p a r a t i o n b e i n g about 30 minutes.  FORAGE PARTICLE SEPARATOR TESTING  FPS S e p a r a t i o n of Hand Chopped A l f a l f a The r e s u l t s  Hay  o f the s e p a r a t i o n o f hand chopped a l f a l f a  T a b l e I I I . The subsample  hay a r e shown i n  b e i n g s e p a r a t e d had a s i g n i f i c a n t e f f e c t  on the p r o p o r t i o n o f sample weight c o l l e c t e d  i n each p a r t i c l e  f r a c t i o n on the FPS. T h i s e f f e c t , however, was  (P <  0.05)  length  c o n s i s t e n t over the t h r e e  TABLE I I I : Average p e r c e n t o f sample weight (n = 4) o f hand chopped a l f a l f a hay c o l l e c t e d i n each p a r t i c l e l e n g t h f r a c t i o n a f t e r each o f t h r e e s e p a r a t i o n runs on the Forage P a r t i c l e S e p a r a t o r . THEORETICAL RANGE OF PARTICLE LENGTHS <4  RUN*  1  10. l  2  11. 7  3  12. 2  4 -10  10- 20  20 -40  (mm)  40- 80  >80  15 .4  a  34. 7  b  23 .0  b  13. 7  3.2  b  16 . 7  b  33. 7  a  21 . 0  a  13. 8  3.2  b  17 .2  b  33. l  a  20 . 6  a  13. 7  3.3  a  Means w i t h i n each p a r t i c l e l e n g t h f r a c t i o n h a v i n g d i f f e r e n t s u p e r s c r i p t s were s i g n i f i c a n t l y d i f f e r e n t (P < 0.05). Run 1; each sample was s e p a r a t e d as a whole sample. Runs 2 & 3; the p a r t i c l e l e n g t h d i s t r i b u t i o n f o r each sample determined by c o n s e c u t i v e l y s e p a r a t i n g the p a r t i c l e l e n g t h f r a c t i o n s c o l l e c t e d i n the p r e v i o u s run.  -34-  was  runs. S i n c e each subsample s h o u l d have had  a similar particle  d i s t r i b u t i o n t h i s e f f e c t must have been caused by subsampling method o f s e p a r a t i o n a l s o had sample weight c o l l e c t e d increase  (P < 0.05)  length fractions  i n each l e n g t h f r a c t i o n . There was  4-10  The  mm)  and a decrease  a significant  i n the s h o r t e r p a r t i c l e i n the 10-20  and 20-40  fractions  when the samples were r e s e p a r a t e d from the p a r t i c l e  fractions  collected  i n the f i r s t  mm  length  run; the 40-80mm and >80mm f r a c t i o n weights  d i d not change s i g n i f i c a n t l y (P > 0.05). difference  error.  a s i g n i f i c a n t e f f e c t on the p r o p o r t i o n o f  i n the amount o f p a r t i c l e s  (<4,  length  There was  no  (P > 0.05), however, between the second and  significant t h i r d runs  i n the  p a r t i c l e l e n g t h d i s t r i b u t i o n o f the samples when they were r e s e p a r a t e d from the p a r t i c l e l e n g t h f r a c t i o n s  collected  i n the second run. F i n n e r e t a l .  (1978) s e p a r a t e d each sample o f a chopped f o r a g e , as a whole, t h r e e times t h e i r simple v i b r a t i n g  s e p a r a t o r and found t h a t the s t a n d a r d d e v i a t i o n f o r  the p e r c e n t sample weight c o l l e c t e d was  o n l y about one p e r c e n t ;  three percent. Therefore,  through  each gap  among the t h r e e  the average c o e f f i c i e n t o f v a r i a t i o n was  i t appears t h a t the r e s u l t s  runs about  o f s e p a r a t i n g chopped  f o r a g e on a simple v i b r a t i n g  s e p a r a t o r are v e r y r e p r o d u c i b l e as l o n g as a  single  of forage p a r t i c l e s  method o f a p p l i c a t i o n  The movement o f p a r t i c l e s length fractions an i n t e r a c t i o n  on  from the middle  between runs 1 and  between the two  to pass over the c o r r e c t  to the s e p a r a t o r i s used.  length fractions  2 indicated  to s m a l l e r  t h a t t h e r e c o u l d have been  l e n g t h groups which caused  gaps when the sample was  shorter p a r t i c l e s  s e p a r a t e d as a whole.  the o t h e r hand, s i n c e the g r e a t e s t p r o p o r t i o n o f sample p a r t i c l e s was medium l e n g t h , s e p a r a t i o n o f these f r a c t i o n s the o p p o r t u n i t y f o r these p a r t i c l e s  as a u n i t may  to pass through  On  of  have i n c r e a s e d  the s m a l l e r gaps. T h i s  q u e s t i o n o f p a r t i c l e s i z i n g a c c u r a c y was i n v e s t i g a t e d i n a s e p a r a t e experiment.  FPS  v s . V i s u a l S e p a r a t i o n o f Machine Chopped Orchardgrass A f t e r the machine chopped o r c h a r d g r a s s  FPS,  Hay  hay had been s e p a r a t e d  on the  the r e s u l t i n g p a r t i c l e l e n g t h f r a c t i o n s were s e p a r a t e d v i s u a l l y t o  determine the a c c u r a c y  o f the FPS i n s e p a r a t i n g chopped f o r a g e p a r t i c l e s on  the b a s i s o f l e n g t h . A mature g r a s s hay was used because i t c o n t a i n e d a h i g h p r o p o r t i o n o f i d e a l l y shaped p a r t i c l e s when chopped. There was no s i g n i f i c a n t d i f f e r e n c e (P > 0.05) between the p a r t i c l e l e n g t h determined u s i n g the FPS and those determined v i s u a l l y was,  distributions  ( T a b l e I V ) . There  however, a c o n s i s t e n t t r e n d w i t h a l l TLC towards an u n d e r e s t i m a t i o n o f  the weight o f p a r t i c l e s i n the 4-10 mm f r a c t i o n and an o v e r e s t i m a t i o n o f the weight o f p a r t i c l e s i n the 20-40, 40-80 and >80 mm f r a c t i o n s when the particle The  l e n g t h d i s t r i b u t i o n s were determined u s i n g the FPS. p r o p o r t i o n o f m a t e r i a l , comprising  each t h e o r e t i c a l p a r t i c l e  length  TABLE IV: P a r t i c l e l e n g t h d i s t r i b u t i o n s ( p e r c e n t o f sample weight) o f mature o r c h a r d g r a s s hay, chopped a t t h r e e t h e o r e t i c a l l e n g t h s o f c u t (TLC), determined by the FPS and by v i s u a l (VIS) s e p a r a t i o n . THEORETICAL RANGE OF PARTICLE LENGTHS (mm) TLC  (mm)  <4  4-10  10-: 20  20-. 40  40- 80  >80  CHI  2  3.18  FPS VIS  15. 9 18. 1  18.7 25.9  30 .3 27 .1  22 .8 20 .8  10 .5 7 .1  2..0 1,.0  5.350  6.35  FPS VIS  10. 8 8.4  15.5 29.7  35 .1 30 .1  23 .5 21 .3  12 .8 8 .8  2..5 1..7  10.625  9.53  FPS VIS  7. 5 6. 2  9.7 18.4  37 .6 39 .6  29 .2 22 .5  13 .9 10 .9  2,.1 1..3  7.647  mean  FPS VIS  10. 9 10. 4  14.1 24.0  34 .7 33 .0  25 .6 21 .6  12 .6 9 .6  2 .2 1 .3  6.254  -36-  f r a c t i o n c o l l e c t e d on the FPS, t h a t was c o r r e c t l y and i n c o r r e c t l y  classified  by l e n g t h i s g i v e n i n T a b l e V. The d i s t r i b u t i o n o f c o r r e c t l y and i n c o r r e c t l y c l a s s i f i e d p a r t i c l e s i n each p a r t i c l e l e n g t h f r a c t i o n was n o t s i g n i f i c a n t l y different difference  (P > 0.05) between TLC samples. There was, however, a s i g n i f i c a n t (P < 0.05) between p a r t i c l e l e n g t h f r a c t i o n s  i n the p e r c e n t  weight o f p a r t i c l e s t h a t was c o r r e c t l y and i n c o r r e c t l y c l a s s i f i e d . The mm  f r a c t i o n c o n t a i n e d the g r e a t e s t p r o p o r t i o n o f c o r r e c t l y  particles  (65.9%) which was s i g n i f i c a n t l y h i g h e r  p r o p o r t i o n c o r r e c t l y c l a s s i f i e d i n the 20-40 mm  classified  (P < 0.05) t h a n the and the >80 mm  fractions,  not s i g n i f i c a n t l y d i f f e r e n t  (P > 0.05) from the p r o p o r t i o n c o r r e c t l y  classified  fractions.  i n the r e m a i n i n g  The >80 mm  f r a c t i o n c o n t a i n e d the  lowest p r o p o r t i o n o f c o r r e c t l y c l a s s i f i e d p a r t i c l e s s i g n i f i c a n t l y less  (39.6%) which was  (P < 0.05) than the p r o p o r t i o n c o r r e c t l y c l a s s i f i e d i n  the o t h e r f r a c t i o n s , w i t h the e x c e p t i o n o f the 20-40 mm The p r o p o r t i o n o f p a r t i c l e s t h a t were i n c o r r e c t l y being either  4-10  fraction.  s i z e d were c l a s s e d as  o v e r s i z e d o r u n d e r s i z e d ; o v e r s i z e d p a r t i c l e s were p a r t i c l e s  t h a t s h o u l d have f a l l e n i n t o a s h o r t e r l e n g t h f r a c t i o n whereas u n d e r s i z e d  TABLE V: P e r c e n t weight o f p a r t i c l e s c o l l e c t e d i n each t h e o r e t i c a l p a r t i c l e l e n g t h f r a c t i o n on the Forage P a r t i c l e S e p a r a t o r (FPS) t h a t were c o r r e c t l y and i n c o r r e c t l y s i z e d . THEORETICAL FPS LENGTH FRACTION <4 4-10 10-20 20-40 40-80 >80 a  _  c  mm mm mm mm mm mm  OVER SIZED 0.0 23.1 33.1 42.9 42.9 64.5  CORRECTLY SIZED 56.8 65.9 58.3 52.1 53.4 39.6  b c  C  b c  a b  b c  a  UNDER SIZED 43.2 11.0 8.7 5.0 3.7 0.0  Values f o r c o r r e c t l y s i z e d p a r t i c l e s with d i f f e r e n t s u p e r s c r i p t s were s i g n i f i c a n t l y d i f f e r e n t (P < 0.05).  -37-  p a r t i c l e s were p a r t i c l e s  t h a t s h o u l d have been c l a s s i f i e d i n t o a l o n g e r  l e n g t h f r a c t i o n . As the gap s i z e on the FPS i n c r e a s e d t h e r e was a s i g n i f i c a n t i n c r e a s e i n the p r o p o r t i o n o f o v e r s i z e d p a r t i c l e s i n the p r o p o r t i o n o f u n d e r s i z e d p a r t i c l e length fractions.  particles  These r e s u l t s  made w h i l e o p e r a t i n g the FPS. L o g i c a l l y  collected  and a decrease  i n the r e s p e c t i v e  are consistent with i t was i m p o s s i b l e  observations  f o r any p a r t i c l e  to be o v e r s i z e d i n the s m a l l e s t l e n g t h f r a c t i o n o r u n d e r s i z e d  i n the l o n g e s t  l e n g t h f r a c t i o n . However, s i n c e many p a r t i c l e s had t o c r o s s a number o f gaps before  a r r i v i n g a t the c o r r e c t l y  s i z e d gap, one would expect an i n c r e a s e d  i n c i d e n c e o f u n d e r s i z i n g i n the s m a l l e r l e n g t h f r a c t i o n s . u s u a l l y r e s u l t e d from l o n g e r ,  This undersizing  i r r e g u l a r l y shaped p a r t i c l e s  initially  c l o g g i n g and then t h r e a d i n g t h e i r way through the s m a l l e r gaps. C o n v e r s e l y , as the p a r t i c l e s p a s s e d down the FPS, the p r o p o r t i o n o f l o n g t o s h o r t e r particles  increased,  i n c r e a s i n g the p r o b a b i l i t y  p a r t i c l e s being  "carried"  p a r t i c l e length  fractions.  over the c o r r e c t gap and f a l l i n g  T a b l e VI shows the p r o p o r t i o n s forage  o f o v e r s i z i n g from  of actual p a r t i c l e lengths  samples, by weight, t h a t were c o r r e c t l y  and i n c o r r e c t l y  the FPS. The TLC d i d n o t have a s i g n i f i c a n t e f f e c t  significantly different percent.  the l o n g e r  i n the chopped c l a s s i f i e d by  (P > 0.05) on the  a c c u r a c y o f p a r t i c l e l e n g t h c l a s s i f i c a t i o n . The p r o p o r t i o n s 20-40, 40-80 and >80 mm p a r t i c l e s  into  smaller  t h a t were c o r r e c t l y  o f <4, 10-20,  c l a s s i f i e d were n o t  (P > 0.05) from each o t h e r b u t o n l y averaged 63.5  The p r o p o r t i o n o f c o r r e c t l y  c l a s s i f i e d 4-10 mm p a r t i c l e s  (38.7%)  was s i g n i f i c a n t l y lower (P < 0.05). No e x p l a n a t i o n f o r t h i s d i f f e r e n c e c o u l d be  found. As p a r t i c l e l e n g t h i n c r e a s e d the i n c i d e n c e o f u n d e r s i z i n g  i n c r e a s e d whereas the i n c i d e n c e o f o v e r s i z i n g decreased. S i n c e  longer  p a r t i c l e s had t o t r a v e l over a g r e a t e r number o f gaps than d i d s h o r t e r  -38-  TABLE V I : P e r c e n t weight o f sample f o r a g e p a r t i c l e s o f the g i v e n a c t u a l ranges o f p a r t i c l e l e n g t h t h a t were c o r r e c t l y and i n c o r r e c t l y s i z e d by the Forage P a r t i c l e S e p a r a t o r . ACTUAL SAMPLE PARTICLE LENGTHS <4 4-10 10-20 20-40 40-80 >80 a  _  D  UNDER SIZED  mm mm mm mm mm mm  CORRECTLY SIZED  0.0 11.2 8.3 15.6 18.6 35.2  59. 8 38.7 61. 2 61. 6 69. 9 64. 8  OVER SIZED  b  40.2 50.2 30.6 22.9 11.5 0.0  a  b  b  b  b  Values f o r c o r r e c t l y s i z e d p a r t i c l e s with d i f f e r e n t s u p e r s c r i p t s were s i g n i f i c a n t l y d i f f e r e n t (P < 0.05).  p a r t i c l e s , b e f o r e b e i n g s e p a r a t e d , t h e r e was these p a r t i c l e s to e r r o n e o u s l y f a l l  through  a greater p r o b a b i l i t y  for  s m a l l gaps and be u n d e r s i z e d .  On  the o t h e r hand, s m a l l e r p a r t i c l e s were more e a s i l y c a r r i e d or pushed by l a r g e r p a r t i c l e s over the c o r r e c t The  gap  c a u s i n g them to be o v e r s i z e d .  a c c u r a c y o f p a r t i c l e l e n g t h c l a s s i f i c a t i o n i n the f o r a g e samples as  a whole, by weight,  i s summarized i n t a b l e V I I . The p r o p o r t i o n s o f  i n c o r r e c t l y c l a s s i f i e d p a r t i c l e s were d i v i d e d through  the f i r s t  following  (+)  gap  ( 1 ) , o r o t h e r gap  the c o r r e c t  gap.  i n t o groups t h a t p a s s e d  ( 2 ) , immediately  There was  no s i g n i f i c a n t d i f f e r e n c e  a c c u r a c y o f c l a s s i f i c a t i o n between TLC. An average were c l a s s i f i e d c o r r e c t l y . Of the r e m a i n i n g 32.38% p a s s e d over the c o r r e c t through  gap  gap w h i l e 75.0% immediately  gap,  and through  91.1%  fell  u n d e r s i z i n g by the FPS,  gap.  on average,  Of those  of p a r t i c l e length.  -39-  of a l l p a r t i c l e s  passed  particles  the immediately f o l l o w i n g  fell  through  T h i s imbalance  resulted  or  i n the  l a t e r gaps w h i l e 11.0%  through  o f those d r o p p i n g p r e m a t u r e l y  p r e c e d i n g the c o r r e c t  o f 56.6%  (-)  incorrectly sized particles,  gaps p r i o r t o r e a c h i n g t h e i r i n t e n d e d gap.  p a s s i n g over the c o r r e c t  preceding  the  gap  between over  i n a n e t 21 p e r c e n t  and  oversizing  TABLE V I I : P e r c e n t weight o f a l l p a r t i c l e s f a l l i n g i n t o the c o r r e c t t r a y ( T ) and i n t o t r a y s b e f o r e (-) and a f t e r (+) the c o r r e c t t r a y on the FPS f o r mature o r c h a r d g r a s s hay chopped a t t h r e e t h e o r e t i c a l l e n g t h s o f c u t (TLC). Q  TRAY TLC  (mm)  -2  +  -1  T  Q  +1  +2  +  3.18* 6.35* 9.53*  2.6 3.0 2.5  8.8 7.9 8.4  54.9 55.7 58.5  29.9 30.8 28.2  3.8 2.7 2.4  mean*  2.7  8.3  56.6  29.5  2.9  Percentage o f p a r t i c l e s f a l l i n g i n t o t r a y s a f t e r the c o r r e c t t r a y was s i g n i f i c a n l y g r e a t e r (P < 0.05) than t h a t f a l l i n g i n t o t r a y s b e f o r e the c o r r e c t t r a y .  Gale and O'Dogherty (1982) a l s o  found a h i g h e r i n c i d e n c e o f o v e r s i z i n g  w i t h t h e i r s e p a r a t o r b u t i t was n o t as pronounced; the p r o p o r t i o n o f p a r t i c l e s c o r r e c t l y c l a s s i f i e d by t h e i r s e p a r a t o r ranged from 65 t o almost 100%  i n some l e n g t h f r a c t i o n s . These r e s e a r c h e r s a l s o demonstrated w i t h  t h e i r separator, that 14.2%  larger  the h o r i z o n t a l  s e t t i n g o f each gap w i d t h had t o be  than h a l f the maximum l e n g t h o f p a r t i c l e i n t e n d e d t o be  s e p a r a t e d by t h a t  gap.  T h e r e f o r e , i f a gap i s s e t a t 5 mm,  the t h e o r e t i c a l  maximum l e n g t h o f p a r t i c l e c a p a b l e o f b e i n g s e p a r a t e d w i l l n o t be 10 mm b u t somewhat l e s s than 10 mm depending on the c h a r a c t e r i s t i c s o f the s e p a r a t o r . For  t h i s reason, a s e p a r a t o r c a n be c a l i b r a t e d by c a l c u l a t i n g the  t h e o r e t i c a l range o f p a r t i c l e l e n g t h s b e i n g s e p a r a t e d based on the degree o f under o r o v e r s i z i n g . Based on the r e s u l t s above, the FPS was r e c a l i b r a t e d 21%  oversizing.  to correct  f o r the  The c a l i b r a t i o n was based on p a r t i c l e s h a v i n g an e q u a l  p r o b a b i l i t y o f b e i n g u n d e r s i z e d o r o v e r s i z e d . T h e r e f o r e the t h e o r e t i c a l l e n g t h s o f p a r t i c l e s c o l l e c t e d i n each p a r t i c l e l e n g t h f r a c t i o n on the FPS were reduced by 21% t o the f o l l o w i n g :  <3.3, 3.3-8.25, 8.25-16.5, 16.5-33.0,  -40-  33.0-66.0, and 21%, For  the  net  >66.0 mm.  p a r t i c l e s up 3.50  to 10 mm  mm  actual  range o f p a r t i c l e l e n g t h s c o l l e c t e d  and  20 mm  20 mm  i n length respectively,  mm  of  i n an o v e r a l l adjustment o f 10.5%  p r o p o r t i o n o f sample p a r t i c l e s then c a l c u l a t e d  c a l i b r a t i o n o f the  each f r a c t i o n on between the  FPS  samples t e s t e d  by  smaller on  i n each o f these new  interpolating  the and  FPS,  theoretical  the  either  side.  particle  results  from  t h e r e was  no  length of p a r t i c l e s c o l l e c t e d  significant difference  (P >  in  0.05)  v i s u a l l y determined p a r t i c l e l e n g t h d i s t r i b u t i o n s  (Table V I I I ) .  In g e n e r a l the  o f f i t were c o n s i d e r a b l y reduced i n d i c a t i n g  Chi  of a l l  squared v a l u e s f o r goodness  a g r e a t e r s i m i l a r i t y between  the  distributions. There was,  FPS  g a i n s 1.75  fraction  separation.  After  two  the  by  i s 10.5%.  separate  o f l a r g e r p a r t i c l e l e n g t h s but  l e n g t h f r a c t i o n s was visual  upper l i m i t s o f p a r t i c l e s i z e  c o n s e c u t i v e gaps s e t to t h e o r e t i c a l l y  p a r t i c l e lengths r e s u l t i n g The  r e d u c i n g the  adjustment i n the  example, w i t h two  loses  By  however, s t i l l  p a r t i c l e length fractions  a significant difference i n the  between  proportion of c o r r e c t l y c l a s s i f i e d  p a r t i c l e s i n each f r a c t i o n (Table I X ) . to be  (P < 0.05)  The  a c c u r a c y o f c l a s s i f i c a t i o n tended  more u n i f o r m , however, w i t h a s i g n i f i c a n t decrease (P < 0.05)  a c c u r a c y o f c l a s s i f i c a t i o n i n the significant  increase  length fractions.  The  (P < 0.05)  shorter p a r t i c l e length fractions  i n the  a c c u r a c y i n the  from o v e r s i z i n g 33.0-66.0 mm  to u n d e r s i z i n g i n the  fractions.  c a l i b r a t i o n . There was u n d e r s i z i n g as  gap  T h i s s h i f t was a similar  t h e r e was  w i t h the  -41-  before  and  a  and  3.3-8.25, 8.25-16.5, 16.5-33.0  increase i n oversizing  s i z e i n c r e a s e d as  sized,  s h i f t e d s i g n i f i c a n t l y (P <  consistent  the  longer p a r t i c l e  d i s t r i b u t i o n of undersized, c o r r e c t l y  o v e r s i z e d p a r t i c l e s w i t h i n f r a c t i o n s was  in  and  objective decrease  calibration.  0.05) and of in  TABLE V I I I : P a r t i c l e l e n g t h d i s t r i b u t i o n s ( p e r c e n t o f sample weight) o f mature o r c h a r d g r a s s hay, chopped a t t h r e e t h e o r e t i c a l l e n g t h s o f c u t (TLC), determined by the Forage P a r t i c l e S e p a r a t o r ( F P S ) and by v i s u a l (VIS) s e p a r a t i o n a f t e r c a l i b r a t i o n o f the FPS. CALIBRATED PARTICLE LENGTH RANGE TLC  <3..3  (mm)  3..38..3  (mm)  8..316..5  16. ,533..0  33.,066..0  >66.0  CHI  2  3.18  FPS VIS  15..9 15..0  18..7 21..5  30..3 26..4  22. .8 25..1  10..5 9..7  2.0 2.4  1.204  6.35  FPS VIS  10..8 6,.9  15..5 22, .5  35..1 30,.5  23..5 24, .3  12, .8 12, .1  2.5 3.7  5.043  9.53  FPS VIS  7,.5 5,.1  9,.7 14, .1  37,.6 33,.1  29, .2 30,.0  13,.9 14, .9  2.1 2.8  3.210  mean  FPS VIS  10, .9 8..6  14, .1 18, .9  34, .7 30,.3  25, .6 26..8  12, .6 12, .5  2.2 3.0  2.551  T a b l e X g i v e s the p r o p o r t i o n s  o f the new ranges o f a c t u a l p a r t i c l e  length  i n a whole sample t h a t were c o r r e c t l y and i n c o r r e c t l y c l a s s i f i e d by the FPS. The  accuracy  o f c l a s s i f i c a t i o n o f each o f these  ranges o f p a r t i c l e  TABLE IX: P e r c e n t weight o f p a r t i c l e s , c o l l e c t e d i n each t h e o r e t i c a l p a r t i c l e l e n g t h f r a c t i o n on the Forage P a r t i c l e S e p a r a t o r (FPS) t h a t were c o r r e c t l y and i n c o r r e c t l y s i z e d a f t e r c a l i b r a t i o n . THEORETICAL FPS LENGTH FRACTION  OVER SIZED  CORRECTLY SIZED  <3.30 3,.30- 8.25 8,.25-16.50 16, .50-33.00 33,.00-66.00 >66.00  0,.0 19..1 24..1 24..2 23..3 33..7  46, ,8 50.. l 55., 0 63.,4 65.,4 66.,3  mm mm mm mm mm mm  a  a  a b  b  b  b  UNDER SIZED 53, .2 30..9* 21..0* 11..9* 11..3* 0,.0  Values f o r c o r r e c t l y s i z e d p a r t i c l e s with d i f f e r e n t s u p e r s c r i p t s were s i g n i f i c a n t l y d i f f e r e n t (P < 0.05). D i s t r i b u t i o n o f c o r r e c t l y and i n c o r r e c t l y s i z e d p a r t i c l e s w i t h i n p a r t i c l e l e n g t h f r a c t i o n was s i g n i f i c a n t l y d i f f e r e n t than t h a t b e f o r e c a l i b r a t i o n (P < 0.05),.  -42-  TABLE X: P e r c e n t weight o f sample f o r a g e p a r t i c l e s o f the g i v e n a c t u a l ranges o f p a r t i c l e l e n g t h t h a t were c o r r e c t l y and i n c o r r e c t l y s i z e d by the Forage P a r t i c l e Separator a f t e r c a l i b r a t i o n . ACTUAL SAMPLE PARTICLE LENGTHS <3.30 3.30- 8.25 8.25-16.50 16.50-33.00 33.00-66.00 >66.00 c  UNDER SIZED  mm mm mm mm mm mm  CORRECTLY SIZED  0.0 15.9 19.2 29.0 30.0 51.1  59.8 38.0 62.9 60.9 65. 7 48.9  OVER SIZED  b c  40.2 46.2 18.0* 10.1* 4.5 0.0*  a  C  Values f o r c o r r e c t l y s i z e d p a r t i c l e s with s u p e r s c r i p t s were s i g n i f i c a n t l y d i f f e r e n t  b c  C  a b  different (P < 0.05).  D i s t r i b u t i o n o f c o r r e c t l y and i n c o r r e c t l y s i z e d range o f p a r t i c l e l e n g t h was s i g n i f i c a n t l y d i f f e r e n t than t h a t b e f o r e c a l i b r a t i o n (P > 0.05).  l e n g t h was  not  significantly different  (P > 0.05)  p r e v i o u s l y g i v e n ranges o f p a r t i c l e l e n g t h the l o n g e s t p a r t i c l e s particles less  undersizing with p a r t i c l e s Undersizing  increased  t h a t were s e p a r a t e d .  a significant shift ranging  o f the l a r g e s t  Within  (P < 0.05)  a similar  (>66  mm)  of  classified represented  the ranges o f from o v e r s i z i n g  i n l e n g t h from 8.25-16.5 mm  p a r t i c l e lengths  (P < 0.05). There was  decrease i n o v e r s i z i n g  the e x c e p t i o n  to 48.9%. T h i s f r a c t i o n , however,  of a l l p a r t i c l e s  p a r t i c l e l e n g t h t h e r e was  mm.  (Table V I ) , w i t h  f o r which the p r o p o r t i o n o f c o r r e c t l y  d e c l i n e d from 64.8  t h a n 4%  from t h a t f o r the  also  and  to  16.5-33.0  significantly  increase i n undersizing  as p a r t i c l e l e n g t h i n c r e a s e d as t h e r e was  and before  calibration. The  accuracy  of length c l a s s i f i c a t i o n of a l l p a r t i c l e s  i n the samples as  a whole, by weight, a f t e r c a l i b r a t i o n i s summarized i n T a b l e XI. d i d not  s i g n i f i c a n t l y change (P > 0.05)  correctly shift  c l a s s i f i e d (57.3%) by  (P < 0.05)  from o v e r s i z i n g ,  the FPS.  the p r o p o r t i o n o f There was,  particles  however, a s i g n i f i c a n t  to u n d e r s i z i n g o f p a r t i c l e s  -43-  Calibration  such t h a t  TABLE X I : P e r c e n t weight o f a l l p a r t i c l e s f a l l i n g i n t o the c o r r e c t t r a y ( T ) and i n t o t r a y s b e f o r e (-) and a f t e r (+) the c o r r e c t t r a y , f o r mature o r c h a r d g r a s s hay chopped a t t h r e e t h e o r e t i c a l l e n g t h s o f c u t (TLC), a f t e r c a l i b r a t i o n o f the Forage P a r t i c l e S e p a r a t o r . Q  TRAY -2+  -1  To  +1  +2+  3.18 6.35 9.53  3.8 4.3 3.4  18.5 17.4 18.2  54.7 56.8 59.6  20.2 19.4 17.2  2.9 2.1 1.7  mean  3.8  18.0  57.3  18.7  2.1  TLC  (mm)  A  t h e r e was no s i g n i f i c a n t d i f f e r e n c e (P > 0.05) between the p r o p o r t i o n o f p a r t i c l e s t h a t were o v e r s i z e d and those  t h a t were u n d e r s i z e d . Of the t o t a l  weight o f chopped f o r a g e t h a t was s e p a r a t e d ,  57.3% o f the p a r t i c l e s were  c l a s s i f i e d c o r r e c t l y w i t h 21.8% b e i n g u n d e r s i z e d and 20.9% b e i n g o v e r s i z e d after  calibration.  I t was t h e r e f o r e c o n c l u d e d suffers  t h a t t h e simple v i b r a t i n g  tray  separator  from an i n h e r e n t i n a b i l i t y t o a c c u r a t e l y c l a s s i f y a l l the p a r t i c l e s  i n a sample o f chopped forage by l e n g t h . The over and u n d e r s i z i n g e r r o r s which o c c u r ,  a r e i n p a r t due t o the d e s i g n o f the machine and i n p a r t due t o  the d i f f i c u l t y o f s e p a r a t i n g i r r e g u l a r l y shaped p a r t i c l e s u s i n g the p r i n c i p l e o f o v e r b a l a n c i n g . On the o t h e r hand, due t o the r e p r o d u c i b i l i t y o f results  and the a b i l i t y  to c a l i b r a t e  t h a t the s e p a r a t o r c l a s s i f i e d FPS  the t h e o r e t i c a l  i n t o each f r a c t i o n ,  c o u l d be used t o a c c u r a t e l y and q u a n t i t a t i v e l y  l e n g t h d i s t r i b u t i o n o f chopped f o r a g e .  -44-  lengths o f p a r t i c l e s  i t was c o n c l u d e d  t h a t the  determine the p a r t i c l e  DESCRIPTION OF PARTICLE LENGTH DISTRIBUTION  Goodness o f F i t o f Mathematical The  coefficients  Functions  o f d e t e r m i n a t i o n f o r the r e g r e s s i o n o f p e r c e n t  c u m u l a t i v e weight u n d e r s i z e on p a r t i c l e  l e n g t h u s i n g the f i v e r e g r e s s i o n  e q u a t i o n s are shown i n T a b l e X I I . The m o d i f i e d W e i b u l l f u n c t i o n (5) c o n s i s t e n t l y gave the h i g h e s t R  2  v a l u e s , f o l l o w e d by the r e g r e s s i o n o f  " p r o b i t " Y on p a r t i c l e l e n g t h ( 4 ) . A l l c o e f f i c i e n t s significant linear  (P < 0.05)  o f d e t e r m i n a t i o n were  w i t h the e x c e p t i o n o f those r e s u l t i n g  r e g r e s s i o n (1) w i t h the d a t a c o l l e c t e d  from  u s i n g the Forage  simple  Particle  Separator. F i g u r e s 3a through 7b show the f i t of the p r e d i c t e d r e g r e s s i o n l i n e s  TABLE X I I : Average R^ v a l u e s f o r the f i v e r e g r e s s i o n models f i t t e d to the d a t a r e s u l t i n g from the Forage P a r t i c l e S e p a r a t o r (FPS) and v i s u a l (VIS) s e p a r a t i o n o f mature o r c h a r d g r a s s hay chopped a t t h r e e t h e o r e t i c a l l e n g t h s o f c u t (TLC). REGRESSION EQUATION* METHOD  * 1: 2: 3: 4:  TLC  1  2  3  4  5  FPS  3.18 6.35 9.53  0 600* 0 616* 0 630*  0 942 0 942 0 933  0 874 0 870 0 875  0 955 0 956 0 960  0 998 0 995 0 994  VIS  3.18 6.35 9.53  0 503 0 479 0 445  0 886 0 876 0 848  0 778 0 695 0 685  0 955 0 976 0 981  0 998 0 995 0 994  bX blogX + blogX = a + blogX C -(BX) 5: Y = 100(1 - e )  * R  2  Y = a + Y = a + logY = a Probit Y  v a l u e not s i g n i f i c a n t  (P > 0.05).  -45-  r e l a t i o n to the observed  data, and the d i s t r i b u t i o n o f r e s i d u a l s f o r each  r e g r e s s i o n e q u a t i o n f o r the FPS a t a TLC  o f 3.18  mm.  s e p a r a t e d o r c h a r d g r a s s hay  t h a t was  From these graphs i t i s c l e a r t h a t e q u a t i o n s 1  4 d i s p l a y e d a s y s t e m a t i c l a c k o f f i t to the observed  d a t a . The  through  residuals  r e s u l t i n g from the use o f e q u a t i o n s 1, 2 and 3 were c o n s i s t e n t l y i n an i n v e r t e d "U"  chopped  distributed  shape w h i l e those r e s u l t i n g from the use o f e q u a t i o n 4  were c o n s i s t e n t l y d i s t r i b u t e d i n a normal "U"  shape. When the d a t a  was  f i t t e d to the m o d i f i e d W e i b u l l f u n c t i o n , however, the r e s i d u a l s were randomly d i s t r i b u t e d around the p r e d i c t e d r e g r e s s i o n l i n e  indicating a  c o n s i s t e n t goodness o f f i t o f the d a t a to the p r e d i c t e d c u m u l a t i v e A f u r t h e r goodness o f f i t t e s t was  performed  curve.  by comparing the d e r i v e d  p a r t i c l e l e n g t h p r o b a b i l i t y d e n s i t y d i s t r i b u t i o n s p r e d i c t e d from r e g r e s s i o n equations The  2, 4 and 5 w i t h those observed u s i n g FPS  and v i s u a l s e p a r a t i o n .  C h i squared v a l u e s from the a n a l y s i s are shown i n T a b l e X I I I . There  a c o n s i s t e n t l a c k o f f i t (P < 0.05) particle  between the observed  was  and p r e d i c t e d  l e n g t h p r o b a b i l i t y d e n s i t y d i s t r i b u t i o n s u s i n g e q u a t i o n 2. The  same  l a c k o f f i t was  seen u s i n g e q u a t i o n 4 b u t o n l y f o r the d i s t r i b u t i o n s t h a t  were determined  u s i n g the FPS.  This r e s u l t  i n d i c a t e s t h a t the  d i s t r i b u t i o n o f p a r t i c l e l e n g t h i n chopped f o r a g e may lognormal observed  al..  i n the d a t a from FPS  (Waldo e t a l . .  1984)  1971;  s u f f i c i e n t , by i t s e l f ,  distribution  s e p a r a t i o n has been observed when  A l l e n et a l . .  by s i e v i n g chopped  1984), rumen c o n t e n t s  and f e c a l samples ( A l l e n e t a l . .  above r e s u l t s a l s o suggest  if  approximate a  d i s t r i b u t i o n . A s i m i l a r l a c k o f f i t to the lognormal  d i s t r i b u t i o n s o f e l o n g a t e d p a r t i c l e s were determined forage  actual  1984;  Pond e t a l . .  (Pond e t 1984).  The  t h a t a h i g h c o e f f i c i e n t o f d e t e r m i n a t i o n i s not  to i n d i c a t e a goodness o f f i t t o a g i v e n d i s t r i b u t i o n  the R.2 v a l u e i s below 0.99.  R  2  v a l u e s between 0.90  -46-  and 0.95  have i n the  FIGURE 3: P l o t s o f FPS s e p a r a t i o n d a t a f o r low q u a l i t y o r c h a r d g r a s s hay chopped a t a TLC o f 3.18 mm showing the f i t o f the observed p o i n t s to the p r e d i c t e d l i n e (a) and the d i s t r i b u t i o n o f r e s i d u a l s (b) u s i n g the r e g r e s s i o n e q u a t i o n Y = a + bX.  -47-  FIGURE 4: P l o t s o f FPS s e p a r a t i o n d a t a f o r low q u a l i t y o r c h a r d g r a s s hay chopped a t a TLC o f 3.18 mm showing the f i t o f the observed p o i n t s t o the p r e d i c t e d l i n e (a) and the d i s t r i b u t i o n o f r e s i d u a l s (b) u s i n g the r e g r e s s i o n e q u a t i o n Y = a + blogX.  -48-  FIGURE 5: P l o t s o f FPS s e p a r a t i o n d a t a f o r low q u a l i t y o r c h a r d g r a s s hay chopped a t a TLC o f 3.18 mm showing the f i t o f the observed p o i n t s t o the p r e d i c t e d l i n e (a) and the d i s t r i b u t i o n o f r e s i d u a l s (b) u s i n g the r e g r e s s i o n e q u a t i o n logY — a + blogX.  -49-  (a)  -30  L  FIGURE 6: P l o t s o f FPS s e p a r a t i o n d a t a f o r low q u a l i t y o r c h a r d g r a s s hay chopped a t a TLC o f 3.18 mm showing the f i t o f the o b s e r v e d p o i n t s to the p r e d i c t e d l i n e (a) and the d i s t r i b u t i o n o f r e s i d u a l s (b) u s i n g the r e g r e s s i o n e q u a t i o n P r o b i t Y = a + blogX.  -50-  (a)  100  e —  CD N  CO w. CD T5 C  80 -  Z> •s  601-  CD CO  40 -  E O *  /  20  9  20  i  i  40  i  »  '  60  '  80  100  120  P a r t i c l e L e n g t h (mm)  (b)  +30 © N  +20  CD TJ C  + 10  CO l_  3  0  *  til  •  •• I  I  -r»-  E - 10 o  -20 - 3 0  L  FIGURE 7: P l o t s o f FPS s e p a r a t i o n d a t a f o r low q u a l i t y o r c h a r d g r a s s hay chopped a t a TLC o f 3.18 mm showing the f i t o f the observed p o i n t s t o the p r e d i c t e d l i n e (a) and the d i s t r i b u t i o n o f r e s i d u a l s (b) u s i n g the m o d i f i e d W e i b u l l f u n c t i o n .  -51-  TABLE X I I I : C h i squared v a l u e s f o r the goodness o f f i t o f the derived p a r t i c l e length p r o b a b i l i t y density d i s t r i b u t i o n s , predicted by t h r e e r e g r e s s i o n e q u a t i o n s , t o those observed a f t e r FPS and v i s u a l (VIS) s e p a r a t i o n o f o r c h a r d g r a s s hay chopped a t t h r e e t h e o r e t i c a l l e n g t h s o f c u t (TLC). REGRESSION EQUATION* METHOD  TLC  FPS (n-6)  3.18 6.35 9.53  18.24* 41.30* 63.87*  15.62* 15.36* 23.71*  3.18 6.35 9.53  29.38* 60.90* 73.90*  8.61 2.01 6.32  VIS  (n-24) #  2  4  5 1.40 4.67 8.20 0.87 10.33 8.77  2: Y = a + b l o g X 4: P r o b i t Y = a + b l o g X C -(BX) 5: Y = 100(1 - e )  * CHI squared v a l u e  p a s t been used as p r o o f distribution  s i g n i f i c a n t (P < 0.05).  t h a t c e r t a i n data approximated a lognormal  (Smith e t a l . . 1984). There was no s i g n i f i c a n t d i f f e r e n c e  (P > 0.05), however, between the observed and p r e d i c t e d p r o b a b i l i t y distributions Weibull-type  density  f o r b o t h the FPS and v i s u a l s e p a r a t i o n d a t a when the m o d i f i e d f u n c t i o n (5) was used.  P r e d i c t i o n o f Median P a r t i c l e Length T a b l e XIV g i v e s the median p a r t i c l e l e n g t h s and  p r e d i c t e d by e q u a t i o n s 2, 4  5 f o r the s e p a r a t i o n o f the hay by the FPS and v i s u a l s e p a r a t i o n . The  median p a r t i c l e l e n g t h s p r e d i c t e d from FPS d a t a were b a s e d on the c a l i b r a t e d ranges o f p a r t i c l e l e n g t h t h a t were c o l l e c t e d on the FPS. Due t o the goodness o f f i t o f the m o d i f i e d W e i b u l l particle  f u n c t i o n f o r b o t h the c u m u l a t i v e  l e n g t h and p a r t i c l e l e n g t h p r o b a b i l i t y  -52-  d e n s i t y d i s t r i b u t i o n s , the  TABLE XIV: Median p a r t i c l e l e n g t h s p r e d i c t e d by t h r e e r e g r e s s i o n e q u a t i o n s f o r FPS and v i s u a l l y (VIS) s e p a r a t e d o r c h a r d g r a s s hay chopped a t t h r e e t h e o r e t i c a l l e n g t h s o f c u t (TLC). REGRESSION EQUATION*  #  METHOD  TLC  2  4  5  FPS (n=6)  3.18 6.35 9.53  11.5 13.7 15.8  10.2 11.7 13.2  12.0 14.1 16.4  VIS (n=24)  3.18 6.35 9.53  8.9 10.9 12.6  11.9 14.0 16.1  11.8 13.8 16.4  2: Y = a + b l o g X 4: P r o b i t Y = a + b l o g X C -(BX) 5: Y = 100(1 - e )  p r e d i c t e d median p a r t i c l e l e n g t h s f o r the v i s u a l l y s e p a r a t e d hay,  determined  u s i n g the W e i b u l l f u n c t i o n , were assumed t o be the " c o r r e c t " v a l u e s , and the o t h e r v a l u e s were s u b j e c t i v e l y compared w i t h them. Lack o f adequate r e p l i c a t i o n i n t h i s case d i d n o t p e r m i t  statistical  t e s t i n g o f any  differences. There was a good agreement between the median p a r t i c l e  length values  p r e d i c t e d from the FPS d a t a and those p r e d i c t e d from v i s u a l s e p a r a t i o n data when the m o d i f i e d W e i b u l l f u n c t i o n was used. T h i s r e s u l t f u r t h e r i n d i c a t e d t h a t the FPS c o u l d be used t o a c c u r a t e l y q u a n t i t a t e the p a r t i c l e  length  d i s t r i b u t i o n i n chopped f o r a g e . There was a l s o good agreement between the median p a r t i c l e l e n g t h v a l u e s p r e d i c t e d by r e g r e s s i o n e q u a t i o n s  4 and 5 when  a p p l i e d t o the v i s u a l s e p a r a t i o n d a t a . However, the f i t t i n g o f the lognormal d i s t r i b u t i o n t o FPS determined underestimate  p a r t i c l e l e n g t h d i s t r i b u t i o n s tended t o  the median p a r t i c l e l e n g t h s o f these d i s t r i b u t i o n s due t o a  c o n s i s t e n t l a c k o f f i t as i n d i c a t e d i n T a b l e X I I I . These r e s u l t s  -53-  support  other  research  t h a t has  shown t h a t the goodness o f f i t o f the  d i s t r i b u t i o n to s i e v i n g d a t a by s e l e c t i o n of sieves missing  s i z e s t h a t are used d u r i n g  from e i t h e r end  These r e s e a r c h e r s obtainable  l i n e a r r e g r e s s i o n may  be  o f the  Only r e g r e s s i o n u s i n g  by  subject  to the same  the m o d i f i e d  Weibull  the  d i s t r i b u t i o n o f p a r t i c l e s i z e s and  t h a t were s i m i l a r to  or v i s u a l s e p a r a t i o n  e x p l i c i t theory  exists  o f a Rosin-Rammler  data.  Murphy  regarding  (or W e i b u l l )  f o r t h a t r e a s o n c o n c l u d e d t h a t i t s use  f o r d e s c r i b i n g the p a r t i c l e s i z e d i s t r i b u t i o n o f  comminuted s u b s t a n c e s . However, as these r e s e a r c h e r s  also pointed  Rosin-Rammler or Weibul f u n c t i o n i s a l s o the s o l u t i o n o f the "hazard r a t e " e q u a t i o n and  out,  the p r o b a b i l i t y f u n c t i o n proposed by  Weibull involved i n  the comminution o f f e e d p a r t i c l e s by hammering, g r i n d i n g , chopping chewing. T h e r e f o r e ,  the use  o f the W e i b u l l  the  differential  (1951) f o r m a t e r i a l f a i l u r e ; b o t h o f these c h a r a c t e r i s t i c s are  forages  that  function resulted i n  length p r o b a b i l i t y density functions  comminution l e a d i n g to the p r o d u c t i o n  appropriate  the  coincidence.  Bohrer (1984) have argued t h a t no  inappropriate  be  i s done  ( A l l e n e t a l . . 1984). A l t h o u g h  those t h a t were o b s e r v e d u s i n g e i t h e r FPS  was  r e g r e s s i o n as  p r e d i c t e d by e q u a t i o n 2 were s i m i l a r to  the r e s u l t s were o b t a i n e d  and  d a t a may  the l a c k o f f i t o f t h i s e q u a t i o n to the d a t a suggests  predicted particle  are  lognormal  f u n c t i o n or the Gamma f u n c t i o n i s not  lengths  "correct" values,  or when p o i n t s  demonstrated t h a t a b e t t e r f i t to s e p a r a t i o n  f i t t i n g e r r o r s as i s l i n e a r r e g r e s s i o n median p a r t i c l e  the  o f the c u m u l a t i v e d i s t r i b u t i o n ( A l l e n e t a l . . 1984).  by u s i n g maximum l i k l i h o o d e s t i m a t o r s  the W e i b u l l  a f f e c t e d by  separation  d i s t r i b u t i o n parameters. F i t t i n g o f d a t a by n o n - l i n e a r using  lognormal  f u n c t i o n appears to  and  be  f o r d e s c r i b i n g the p a r t i c l e l e n g t h d i s t r i b u t i o n i n chopped  when they have been s e p a r a t e d  on a simple v i b r a t i n g t r a y  -54-  separator.  No methods, however, have been proposed f o r the d e s c r i p t i o n o f the spread o f p a r t i c l e lengths  i n a sample o f chopped forage  D e s c r i p t i o n o f Spread U s i n g t h e W e i b u l l One o f the major b e n e f i t s o f u s i n g the d i s t r i b u t i o n o f p a r t i c l e l e n g t h s l o g mean and l o g s t a n d a r d  using  this  function.  Function the lognormal d i s t r i b u t i o n i s t h a t  can be d e s c r i b e d by two parameters, the  d e v i a t i o n . However, s i n c e the lognormal  d i s t r i b u t i o n d i d n o t s a t i s f a c t o r i l y f i t the d a t a from FPS s e p a r a t i o n , method o f d e s c r i b i n g the s p r e a d o f p a r t i c l e s u s i n g  the W e i b u l l  a  f u n c t i o n was  required. I f one examines the a c t i o n o f the parameters i n the W e i b u l l  function  ( F i g u r e 8 ) , one can see t h a t the B parameter c o n t r o l s the s h i f t o f the curve (ie.  change i n curve p o s i t i o n from l e f t  t o r i g h t on the X a x i s ) w h i l e the C  parameter c o n t r o l s the shape ( i e . the r e l a t i v e s l o p e  and symmetry o f the  c u r v e ) . When base "e" i s used i n the f u n c t i o n , a change i n the shape parameter (C) causes the curve t o p i v o t around the 63.2 p e r c e n t i l e p o i n t . Therefore,  b o t h the B and C parameters must change when e i t h e r the median o f  a g i v e n p a r t i c l e l e n g t h d i s t r i b u t i o n changes o r the d i s t r i b u t i o n o f p a r t i c l e lengths  around a g i v e n median changes. However, when base 2 i s used i n the  Weibull  f u n c t i o n ( F i g u r e 9 ) , the p i v o t p o i n t f o r changes i n the shape o f a  curve becomes the 50 p e r c e n t i l e p o i n t o r the median p a r t i c l e  length  value  f o r a g i v e n d i s t r i b u t i o n . The use o f a d i f f e r e n t base changes the v a l u e s o f the two parameters b u t does n o t a l t e r the f i t o f the f u n c t i o n . By u s i n g base 2,  changes i n the shape parameter (C) do n o t a l t e r the v a l u e  o f the s h i f t  parameter (B) which c a n then be used t o c a l c u l a t e the median p a r t i c l e length,  the v a l u e  o f which i s determined by 1/B.  -55-  0  10  20  30  40  50  60  P a r t i c l e L e n g t h (mm)  FIGURE 8: Changes i n shape o f the m o d i f i e d W e i b u l l c u m u l a t i v e f r e q u e n c y d i s t r i b u t i o n w i t h v a r i o u s B and C parameter v a l u e s when "base e" i s used i n the e q u a t i o n .  -56-  P a r t i c l e L e n g t h (mm)  FIGURE 9 : Changes i n shape o f the m o d i f i e d W e i b u l l c u m u l a t i v e f r e q u e n c y d i s t r i b u t i o n w i t h v a r i o u s B and C parameter v a l u e s when "base 2" i s used i n the e q u a t i o n .  -57-  The  shape o f a c u m u l a t i v e  a s s o c i a t e d increment  curve  i s determined  by the shape o f the  or d e n s i t y f u n c t i o n . T h e r e f o r e when base 2 was  used i n  the W e i b u l l f u n c t i o n , the v a l u e o f the C parameter c o u l d be used to d e s c r i b e the shape o f the p a r t i c l e l e n g t h d i s t r i b u t i o n when a p p l i e d to s e p a r a t i o n d a t a . The  e f f e c t o f changing  the c u m u l a t i v e  the v a l u e o f the C parameter on the shape of  and d e r i v e d increment  ( d e n s i t y ) curves when base 2 was  i n the f u n c t i o n i s shown i n F i g u r e s 10 and 11 r e s p e c t i v e l y ; a l l the  used curves  have the same v a l u e f o r B and t h e r e f o r e p r e d i c t the same median p a r t i c l e l e n g t h . With C e q u a l to 1.0,  the cumulative  curve  i s the same as a  simple  e x p o n e n t i a l c u r v e . However, as the v a l u e o f the C parameter i n c r e a s e s , can see t h a t the i n c r e m e n t a l d i s t r i b u t i o n becomes l e s s skewed to the  one  right  such t h a t when C i s e q u a l to 3.212, a normal d i s t r i b u t i o n i s approximated. I f the v a l u e o f C becomes even l a r g e r , to the l e f t .  Therefore,  the d i s t r i b u t i o n then becomes skewed  i f two p a r t i c l e l e n g t h d i s t r i b u t i o n s have the same  median, b u t d i f f e r e n t C v a l u e s , the spread o f the p a r t i c l e s around the mean must be d i f f e r e n t ;  and  Furthermore, as can be  t h e r e f o r e , the two  d i s t r i b u t i o n s must be  seen from F i g u r e 10,  as the v a l u e o f C i n c r e a s e s to  3.212, the r e l a t i v e spread o f the p a r t i c l e s around the median I f two C,  different.  decreases.  d i s t r i b u t i o n s have d i f f e r e n t median v a l u e s , b u t s i m i l a r v a l u e s  of  the r e l a t i v e spread o f p a r t i c l e s around each mean i s e q u a l . For example,  two  d i s t r i b u t i o n s have median p a r t i c l e l e n g t h s o f 10 and 20 mm  and  the v a l u e o f C i s 1.5  and 0.05)  and  f o r b o t h d i s t r i b u t i o n s . U s i n g the v a l u e s o f B  the v a l u e o f C i n the W e i b u l l f u n c t i o n , one  range i n l e n g t h o f p a r t i c l e s c o l l e c t e d between the 25 and p o i n t s o f the c u m u l a t i v e  respectively  can c a l c u l a t e 75  percentile  d i s t r i b u t i o n u s i n g the f o l l o w i n g e q u a t i o n :  -58-  (0.1 the  0  10  20  30  40  50  60  Particle L e n g t h (mm)  FIGURE 10: Changes i n shape o f the m o d i f i e d W e i b u l l c u m u l a t i v e f r e q u e n c y d i s t r i b u t i o n g i v e n a f i x e d B parameter v a l u e and t h r e e C parameter v a l u e s when "base 2" i s used i n the e q u a t i o n .  -59-  FIGURE 11: Changes i n shape of. the m o d i f i e d W e i b u l l p r o b a b i l i t y d e n s i t y d i s t r i b u t i o n g i v e n a f i x e d B parameter v a l u e and t h r e e C parameter v a l u e s when "base 2" i s u s e d i n t h e e q u a t i o n .  -60-  ( - ( l o g (Y - 1 W  Hog  l o g 2)) |  C X  10  B where:  X  the l e n g t h percentile  Y  the  percentile  C  the  shape  B  the s h i f t parameter which i s e q u a l t o t h e i n v e r s e o f the median p a r t i c l e l e n g t h .  The  range  of particle  lengths  for  t h e two e x a m p l e p a r t i c l e  11.13  - 31.75 mm  value  ( 1 0 . 3 1 a n d 20.62 mm)  length and  gives  1.031) w h i c h Therefore,  distribution  the  coefficient  distributions this  reason  spread  may  f o r t h e two p a r t i c l e  length  therefore  i n describing the r e l a t i v e  around  determine occur  to describe  named t h e c o e f f i c i e n t  indicated  o f spread  and t e s t length  particle (1.031  distributions. o f t h e shape o f  from  the median p a r t i c l e  i n the determination  the r e l a t i v e o f chopped  visual  tended to length  t h e FPS c o u l d  lengths  of  lengths. For  t h e FPS a n d  f o r the p a r t i c l e  although  be u s e d t o  o f the d i s t r i b u t i o n s ,  o f shape o f t h e d i s t r i b u t i o n .  -61-  to  o f spread.  h a y . FPS s e p a r a t i o n  o f spread that  single  t h e mean  spread  median p a r t i c l e  the median p a r t i c l e  the c o e f f i c i e n t s  This  as an i n d i c a t o r  and  o f skewness) b u t i n a manner s i m i l a r  c a n be u s e d  the c o e f f i c i e n t  distributions.  error  around  not only  as a  median  lengths  acts  points  - 15.87 mm  of lengths  by the r e s p e c t i v e  of particle  o f chopped orchardgrass  overestimate  accurately  lengths  a r e 5.56  the range  t h e same o r d i s s i m i l a r  the C parameter  XV g i v e s  separation  spread  (normal v s . degree  having  a n d was  Table  Expressing  are equivalent  of particle  forages  distributions  and d i v i d i n g  of variation  d i v i d e d b y 100  parameter  length  the C parameter  the  point  a t t h e 25 o r 75  between t h e 25th and 75th p e r c e n t i l e  respectively.  the r e l a t i v e  of particles point.  some  Iti s  TABLE XV: C o e f f i c i e n t s o f spread f o r o r c h a r d g r a s s hay chopped a t t h r e e t h e o r e t i c a l l e n g t h s o f c u t (TLC) as determined from FPS and v i s u a l (VIS) s e p a r a t i o n . THEORETICAL LENGTH OF CUT  more l i k e l y ,  (mm)  3.18  6.35  9.53  FPS  1.142  1.275  1.524  VIS  1.068  1.132  1.289  however, t h a t the s e p a r a t i o n i n t o many more p a r t i c l e l e n g t h  f r a c t i o n s by v i s u a l s e p a r a t i o n may have r e s u l t e d o f the W e i b u l l  f u n c t i o n t o the d i s t r i b u t i o n s .  -62-  i n a more a c c u r a t e  fitting  SUMMARY  The r e s e a r c h i n t h i s c h a p t e r  investigated  v i b r a t i n g t r a y Forage P a r t i c l e S e p a r a t o r particles  on the b a s i s o f l e n g t h ,  the a c c u r a c y o f a simple  (FPS) i n s e p a r a t i n g  and the d e s c r i p t i o n o f the  p a r t i c l e l e n g t h d i s t r i b u t i o n s u s i n g mathematical with v i s u a l separation,  the FPS c o r r e c t l y c l a s s i f i e d  the s e p a r a t e d p a r t i c l e s ,  by w e i g h t ,  c a l i b r a t i o n o f the t h e o r e t i c a l fractions  functions.  By comparison  o n l y 57.3  on the b a s i s o f l e n g t h .  percent  However,  p a r t i c l e lengths being separated  of  after  into  the FPS a c c u r a t e l y d e s c r i b e d the p a r t i c l e  d i s t r i b u t i o n i n the chopped forage Of the mathematical  functions  t h a t was  length d i s t r i b u t i o n s  t h a t were t e s t e d ,  the  gave the b e s t f i t  from r e g r e s s i o n ,  however,  the  the W e i b u l l  particle Based on the function  the  d i d not approximate a lognormal  T h i s was p r o b a b l y due to problems a s s o c i a t e d w i t h f i t t i n g  lognormal d i s t r i b u t i o n by simple l i n e a r r e g r e s s i o n . on the o t h e r hand, f i t  The W e i b u l l  length d i s t r i b u t i o n s  well.  the W e i b u l l f u n c t i o n was more a p p r o p r i a t e  than the l o g n o r m a l d i s t r i b u t i o n f o r use d i s t r i b u t i o n i n chopped f o r a g e .  the  function,  the FPS and v i s u a l s e p a r a t i o n d a t a e q u a l l y  i t was c o n c l u d e d t h a t  f u n c t i o n was  fit  to the d a t a . When u s i n g FPS s e p a r a t i o n d a t a ,  determined p a r t i c l e l e n g t h d i s t r i b u t i o n s distribution.  lognormal  t h a t were determined by v i s u a l s e p a r a t i o n .  d i s t r i b u t i o n of residuals  length  separated.  d i s t r i b u t i o n and the W e i b u l l f u n c t i o n b o t h s i g n i f i c a n t l y  particle  resulting  on the FPS, t h e r e was an e q u a l degree o f o v e r s i z i n g and  u n d e r s i z i n g such t h a t  Therefore  forage  i n d e s c r i b i n g the p a r t i c l e  A method f o r d e s c r i b i n g the  length  spread of  u s i n g the C parameter o f the m o d i f i e d W e i b u l l  described.  -63-  CHAPTER I I THE EFFECT OF PROCESSING METHOD AND FORAGE TYPE ON THE PARTICLE LENGTH DISTRIBUTION OF DM, CP AND ADF IN PROCESSED FORAGES  INTRODUCTION  The  r e d u c t i o n o f p a r t i c l e s i z e i n f o r a g e s f e d t o ruminants by chopping  and  grinding  reduces f e e d wastage, c a n i n c r e a s e v o l u n t a r y f e e d consumption,  and  has been shown t o have an e f f e c t on d i g e s t i o n  and r a t e  o f passage o f  these f e e d s . P r o c e s s i n g o f d i f f e r e n t f o r a g e s u s i n g i d e n t i c a l methods, has therefore routinely  been used i n e x p e r i m e n t a t i o n i n v e s t i g a t i n g the  d i g e s t i b i l i t y o f d i f f e r e n t f o r a g e types and the e f f e c t o f p a r t i c l e s i z e on digestion  p r o c e s s e s . L i t t l e r e s e a r c h , however, has been done t o see i f  similar particle size distributions  a r e produced when d i f f e r e n t f o r a g e s a r e  p r o c e s s e d u s i n g the same method. Recent r e s e a r c h has shown t h a t conditions,  c a n r e s u l t i n the p r o d u c t i o n o f s i g n i f i c a n t l y d i f f e r e n t  size distributions and  d i f f e r e n t f o r a g e s , ground under i d e n t i c a l  fiber fractions  (Osbourn e t a l . . 1981), and t h a t  (DM),  . I f these d i f f e r e n c e s  (CP)  that  a r e produced ( J a s t e r  and Murphy,  i n p a r t i c l e s i z e d i s t r i b u t i o n o f d r y matter  CP, and f i b e r a r e l a r g e  enough w i t h i n o r between f o r a g e s when  p r o c e s s e d under i d e n t i c a l c o n d i t i o n s , size distributions  the crude p r o t e i n  o f the f o r a g e c a n be d i f f e r e n t i a l l y d i s t r i b u t e d  throughout the range o f p a r t i c l e s i z e s 1983)  particle  lack of q u a n t i f i c a t i o n  could introduce uncontrolled v a r i a t i o n  o f the p a r t i c l e  into  experimental  results. T h e r e f o r e , the o b j e c t i v e  o f the f o l l o w i n g  study was t o q u a n t i t a t i v e l y  determine the e f f e c t o f p r o c e s s i n g method (hammermilling o r chopping a t  -64-  t h r e e t h e o r e t i c a l l e n g t h s o f c u t [TLC]) and f o r a g e type ( a l f a l f a and h i g h and low q u a l i t y o r c h a r d g r a s s hay) on the p a r t i c l e l e n g t h d i s t r i b u t i o n o f DM,  CP, and a c i d d e t e r g e n t f i b e r (ADF)  i n processed forage.  -65-  LITERATURE REVIEW  Research has shown t h a t the r a t e o f m i c r o b i a l d i g e s t i o n , r a t e o f passage and, be  therefore,  the e x t e n t  o f d i g e s t i o n o f f e e d s t u f f s f e d t o ruminants may  d i r e c t l y a f f e c t e d by the p a r t i c l e s i z e d i s t r i b u t i o n i n the f e e d .  e t a l . (1980) found t h a t d e c r e a s i n g  the p a r t i c l e s i z e o f f o r a g e s  Robles  increased  the r a t e o f i n v i t r o c e l l w a l l d i g e s t i o n i n a l f a l f a . When v a r i o u s concentrates  were s u b j e c t e d  t o i n v i t r o and i n s i t u d i g e s t i o n , E h l e e t a l .  (1982) found t h a t the p a r t i c l e s i z e o f l i n s e e d meal had an e f f e c t on the r a t e o f DM d i g e s t i b i l i t y whereas the p a r t i c l e s i z e o f the o t h e r concentrates  d i d not.  P a r t i c l e s i z e , however, d i d n o t appear t o a f f e c t the  i n v i t r o o r i n s i t u d i g e s t i o n o f CP. The  p a r t i c l e s i z e o f f e e d s t u f f s appears t o have i t s g r e a t e s t e f f e c t on  the r a t e o f passage o f p a r t i c l e s from the rumen, which i n t u r n a f f e c t s the d i g e s t i b i l i t y o f the d i e t . J a s t e r and Murphy (1983), when f e e d i n g hay 2160  t o H o l s t e i n h e i f e r s , found t h a t r e d u c i n g  the median p a r t i c l e  alfalfa length  from  t o 1440 um (determined by s i e v i n g ) s i g n i f i c a n t l y d e c r e a s e d DM and ADF  d i g e s t i b i l i t y . Osbourn e t a l . (1981) found t h a t d i f f e r e n c e s as s m a l l as 0.2 i n the M o d u l i o f F i n e n e s s f o r d i f f e r e n t ground f o r a g e s the o r g a n i c  matter and c e l l w a l l d i g e s t i b i l i t y o f the f o r a g e s  lambs. T h e r e f o r e , particle  significantly altered  under c e r t a i n c o n d i t i o n s ,  when f e d t o  a r e l a t i v e l y small d i f f e r e n c e i n  s i z e can s i g n i f i c a n t l y a f f e c t the d i g e s t i b i l i t y and r a t e o f passage  o f some f e e d s t u f f s i n ruminants. Any  study o f the e f f e c t o f forage  p a r t i c l e s i z e on parameters o f  d i g e s t i o n and r a t e o f passage i n ruminants u s u a l l y r e q u i r e s f e e d s t u f f f i r s t be p r o c e s s e d . P r o c e s s i n g f e e d wastage and i n c r e a s e v o l u n t a r y  o f forages  t h a t the  i s a l s o used t o reduce  f e e d consumption when c o n d u c t i n g  -66-  r e s e a r c h s t u d y i n g the e f f e c t o f d i f f e r e n t f o r a g e c h a r a c t e r i s t i c s utilization.  I n most o f these t r i a l s ,  the d i f f e r e n t f e e d s t u f f s  p r o c e s s e d u s i n g the same method, b u t the a c t u a l o f the p r o c e s s e d f e e d s t u f f s employed, i n c l u d i n g theoretical  s c r e e n s i z e used i n g r i n d i n g  distributions  o r hammermilling, o r the  l e n g t h o f c u t (TLC) used d u r i n g chopping, a r e r e p o r t e d . Osbourn  same equipment, m i l l e d  d i f f e r e n t f o r a g e s , h a r v e s t e d w i t h the  through the same s i z e s c r e e n and/or p a s s e d through  same p e l l e t i z e r had s i g n i f i c a n t l y d i f f e r e n t M o d u l i o f F i n e n e s s . The  researchers also distributions affected  found t h a t  The are  the d i f f e r e n c e s  i n the p a r t i c l e  size  between f o r a g e s p r o c e s s e d by an i d e n t i c a l method s i g n i f i c a n t l y  the comparison o f the d i g e s t i b i l i t y o f these f o r a g e s .  research involving  o f f o r a g e s r e p o r t e d i n the l i t e r a t u r e  b a s e d on the d i s t r i b u t i o n o f DM. I f p r o t e i n  and f i b e r a r e e v e n l y  by weight, throughout the range o f p a r t i c l e s i z e s  o f p r o c e s s e d f o r a g e , the p a r t i c l e s i z e d i s t r i b u t i o n s similar.  Similar  the chopping o f f o r a g e s c o u l d n o t be found.  particle size distributions  distributed,  be  have been  have n o t been determined; o n l y the methods  e t a l . (1981), however, found t h a t  the  particle size  on f o r a g e  i n a sample  o f DM, CP and ADF w i l l  I f the c o n c e n t r a t i o n o f CP o r ADF changes as p a r t i c l e  changes, the d i s t r i b u t i o n o f these n u t r i e n t s  size  on the b a s i s o f p a r t i c l e  size  w i l l be d i f f e r e n t from the p a r t i c l e s i z e d i s t r i b u t i o n o f DM. The  processing of different feedstuffs  to d i f f e r e n t i a l l y a f f e c t the d i s t r i b u t i o n s p a r t i c l e s i z e . Ehle  (1984) found t h a t  components i n c r e a s e d w i t h i n c r e a s i n g  u s i n g the same method does appear o f CP and ADF i n r e l a t i o n t o  the c o n c e n t r a t i o n o f c e l l  wall  p a r t i c l e s i z e w i t h i n a sample o f c o a r s e  chopped a l f a l f a and two m a t u r i t i e s o f smooth bromegrass hay. He a l s o that  the r a t e  found  o f i n c r e a s e was g r e a t e r i n the a l f a l f a hay than i t was i n the  bromegrass hays, w i t h i n which the r a t e  o f i n c r e a s e was g r e a t e r i n the more  -67-  mature bromegrass hay. concentration  J a s t e r and Murphy (1983) a l s o found t h a t the  o f chopped a l f a l f a hay  sample i n c r e a s e d  as p a r t i c l e  crude p r o t e i n c o n c e n t r a t i o n Therefore,  the p a r t i c l e  size  particles  increased.  within a  given  They a l s o demonstrated  decreased with i n c r e a s i n g p a r t i c l e  size distributions  o f DM,  CP  ADF  and  ADF  that  size.  may  differ  w i t h i n samples o f p r o c e s s e d f o r a g e and between f o r a g e s p r o c e s s e d under identical conditions. have a s i g n i f i c a n t  effect  passage o f d i f f e r e n t forage p a r t i c l e  I f these d i f f e r e n c e s are  l a r g e enough, they a l s o  on the comparison o f the d i g e s t i b i l i t y and  f o r a g e s and  the d e t e r m i n a t i o n o f the  s i z e on the p r o c e s s o f d i g e s t i o n i n the  ( -68-  effect  ruminant.  of  could  rate  of  reducing  MATERIALS AND  PROCESSING AND  METHODS  P A R T I C L E LENGTH SEPARATION OF  FORAGE  A p p r o x i m a t e l y 100 k i l o g r a m s each o f b a l e d a l f a l f a q u a l i t y o r c h a r d g r a s s hay l e n g t h s o f c u t (TLC)  (OGH  and OGL)  (3.18, 6.35  (ALF) and h i g h and  were chopped a t t h r e e t h e o r e t i c a l  and 9.53  mm),  w i t h a John Deere, Model 35  f o r a g e h a r v e s t e r , and hammer-milled through a 12.7  mm  s c r e e n i n a Haybuster.  The b a l e s o f each f o r a g e were broken open and the sheaves randomly  equally  treatment were then chopped and sampled  f o r each chopped, f o r a g e  t h r e e times u s i n g the same procedure  d e s c r i b e d i n Chapter 1. Hammermilled f o r a g e was  below the hammermill s c r e e n , mixed and then sampled  collected directly  t h r e e times by  sampling" w i t h a s m a l l s h o v e l . Each hammermilled sample was not  l e s s than s i x randomly  p r o c e s s e d f o r a g e were a l s o used f o r c h e m i c a l a n a l y s i s . analysis,  and  d i s t r i b u t e d between the f o u r p r o c e s s i n g treatments i n a b a l a n c e d  t h r e e by f o u r f a c t o r i a l d e s i g n . The sheaves  t h a t was  low  selected  subsamples.  taken and composited A l l samples,  Grab samples  "grab  a composite  of  of a l l  f o r each f o r a g e type to be  e x c l u d i n g those f o r c h e m i c a l  were then s e p a r a t e d i n t o 6 p a r t i c l e l e n g t h f r a c t i o n s  3.3-8.25, 8.25-16.5, 16.5-33.0, 33.0-66.0 and >66.0 mm) P a r t i c l e S e p a r a t o r (FPS) as d e s c r i b e d i n Chapter  (<3.3,  on the Forage  1.  CHEMICAL A N A L Y S I S  After  separation, s i m i l a r p a r t i c l e length fractions  from samples  each treatment c o m b i n a t i o n were composited to y i e l d a s i n g l e length fractions  set of p a r t i c l e  f o r each treatment combination. These composite  -69-  within  particle  l e n g t h f r a c t i o n s and the u n s e p a r a t e d f o r a g e samples  were then ground  a 1.0 mm s c r e e n i n a W i l e y m i l l b e f o r e b e i n g a n a l y z e d f o r d r y matter (oven d r y i n g a t 65 degrees C e l s i u s ) , Allen,  through (DM)  crude p r o t e i n (CP) ( P a r k i n s o n and  1975) and A c i d D e t e r g e n t F i b e r  (ADF) (Waldern,  1971) c o n t e n t .  CALCULATIONS  The weight o f CP and ADF i n each p a r t i c l e l e n g t h f r a c t i o n o f a g i v e n sample was c a l c u l a t e d by m u l t i p l y i n g the weight o f the sample c o l l e c t e d i n each p a r t i c l e l e n g t h f r a c t i o n on the FPS by the r e s p e c t i v e  nutritional  c o n t e n t o f the f r a c t i o n . The p e r c e n t weight o f CP and ADF i n each  fraction  was then c a l c u l a t e d . The median p a r t i c l e l e n g t h (MPL) and c o e f f i c i e n t o f s p r e a d (CS) o f DM, CP,  and ADF f o r each sample were determined by the methods d e s c r i b e d i n  Chapter 1 u s i n g the M o d i f i e d W e i b u l l f u n c t i o n . The MPL f o r each n u t r i e n t i n a f o r a g e sample i s d e f i n e d as the l e n g t h a t which 50% o f the c u m u l a t i v e p e r c e n t weight o f the n u t r i e n t i s found. F o r example, i f the DM MPL i s 10 mm,  50% o f the t o t a l weight o f DM i n the sample i s l o c a t e d i n the p a r t i c l e s  t h a t a r e l e s s than 10 mm  i n l e n g t h and 50% o f the DM i s l o c a t e d i n the  p a r t i c l e s g r e a t e r than 10mm the CP MPL i s 7 mm,  i n l e n g t h . The same a p p l i e s f o r CP o r ADF. I f  50% o f the t o t a l weight o f CP i n the sample i s l o c a t e d  i n the p a r t i c l e s t h a t a r e l e s s than 7 mm  i n l e n g t h and 50% o f the CP i s  l o c a t e d i n the p a r t i c l e s g r e a t e r than 7 mm  i n l e n g t h . The d e t e r m i n a t i o n o f  the c u m u l a t i v e d i s t r i b u t i o n o f CP and ADF was the same as t h a t f o r DM except t h a t the p e r c e n t weight o f each n u t r i e n t was used i n p l a c e o f the p e r c e n t weight o f DM. The MPL o f each p a r t i c l e l e n g t h f r a c t i o n o f a g i v e n sample s e p a r a t e d on  -70-  the FPS was  determined  the independent was  by s o l v i n g the a p p r o p r i a t e r e g r e s s i o n e q u a t i o n f o r  v a r i a b l e X when the c u m u l a t i v e p e r c e n t weight u n d e r s i z e  e q u a l t o the mid p o i n t o f the c u m u l a t i v e  given p a r t i c l e  sample weight c o l l e c t e d i n a  l e n g t h f r a c t i o n . For example, i f the range o f p e r c e n t  c u m u l a t i v e weight c o l l e c t e d i n a g i v e n t r a y was was  72%  (Y)  65 t o 79%,  the mid p o i n t  (Y)  ((65 + 79) / 2 ) .  STATISTICAL ANALYSIS  The was  e f f e c t o f treatment  combination  t e s t e d by G e n e r a l L i n e a r H y p o t h e s i s  on the MPL  and CS o f DM,  CP and  ADF  u s i n g the BMDrlOV packaged program  o f the U n i v e r s i t y o f B r i t i s h Columbia. The G e n e r a l L i n e a r H y p o t h e s i s  was  as  follows:  Y where:  l j k  ^ij'k  = =  u + F t  b  e  ±  + Pj + F P  i:J  +  E  i  J  dependent v a r i a b l e : MPL  k  or  CS.  u  =  the o v e r a l l mean.  F^  =  the e f f e c t o f the i ' t h type o f f o r a g e .  Pj  =  the e f f e c t o f the j ' t h method o f p r o c e s s i n g .  FP-JJ  =  the e f f e c t due  to the i n t e r a c t i o n between 1  the i ' t h type o f f o r a g e and the j t h method of processing. E^jk  =  the u n e x p l a i n e d r e s i d u a l e r r o r a s s o c i a t e d w i t h each sample.  D i f f e r e n c e s between means f o r the treatment Duncan's M u l t i p l e Range t e s t The  (a =  combinations  were t e s t e d u s i n g  0.5).  r e l a t i o n s h i p between p a r t i c l e l e n g t h and n u t r i t i o n a l c o n t e n t w i t h i n  each treatment  combination was  t e s t e d u s i n g l i n e a r r e g r e s s i o n . Both  -71-  simple  linear The  (Y = a + bX) and c u r v i l i n e a r r e g r e s s i o n  (Y = a + b l o g X ) were used.  p a r t i c l e l e n g t h f r a c t i o n MPL was the independent v a r i a b l e (X) and the  percent  n u t r i e n t c o n t e n t o f the f r a c t i o n was the dependent v a r i a b l e ( Y ) .  R e g r e s s i o n a n a l y s i s was performed u s i n g  the BMDP:IR packaged program  a v a i l a b l e a t the U n i v e r s i t y o f B r i t i s h Columbia. The e f f e c t o f treatment c o m b i n a t i o n on the r e l a t i o n s h i p between p a r t i c l e l e n g t h and n u t r i e n t c o n t e n t was t e s t e d by homogeneity o f r e g r e s s i o n c o e f f i c i e n t s u s i n g  the U.B.C.  Computing C e n t e r packaged program, SL:TEST. D i f f e r e n c e s between r e g r e s s i o n c o e f f i c i e n t s and r e g r e s s i o n l i n e s were s e p a r a t e d  by S c h e f f e ' s  multiple  range  t e s t which was a l s o p a r t o f the same program. The  e f f e c t o f treatment c o m b i n a t i o n on the d e v i a t i o n o f CP and ADF  median p a r t i c l e l e n g t h s each f o r a g e  and c o e f f i c i e n t s o f s p r e a d from those o f DM w i t h i n  was t e s t e d u s i n g  the same G e n e r a l L i n e a r H y p o t h e s i s as was used  above. The d i f f e r e n c e between the MPL f o r DM and t h a t f o r CP o r ADF w i t h i n each sample was c a l c u l a t e d by s u b t r a c t i n g the v a l u e  determined f o r DM from  t h a t determined f o r CP and f o r ADF. I n d i v i d u a l t t e s t s were used t o t e s t the n u l l h y p o t h e s i s t h a t the d i f f e r e n c e between the DM and CP, and the DM and ADF median p a r t i c l e  lengths,  s i g n i f i c a n t l y d i f f e r e n t from  w i t h i n each treatment combination, was n o t zero.  -72-  RESULTS AND  FORAGE NUTRITIONAL  Forage CP and ADF  DISCUSSION  COMPOSITION  Content  The n u t r i t i o n a l c o m p o s i t i o n o f the t h r e e f o r a g e s i s g i v e n i n T a b l e X V I . The  t h r e e f o r a g e s t h a t were p r o c e s s e d had s i g n i f i c a n t l y d i f f e r e n t  (P < 0.05)  CP c o n t e n t s ; the OGH hay had the h i g h e s t CP c o n t e n t , OGL hay the lowest, w h i l e the CP c o n t e n t o f ALF was i n t e r m e d i a t e . OGL and ALF had s i m i l a r c o n t e n t s which were s i g n i f i c a n t l y h i g h e r  ADF  (P < 0.05) than t h a t f o r OGH.  R e l a t i o n s h i p Between P a r t i c l e Length and N u t r i e n t  Content  F i g u r e s 11 and 12 show the CP and ADF c o n t e n t o f the p a r t i c l e l e n g t h fractions  i n each o f the p r o c e s s e d f o r a g e s as an average  determined  o f the v a l u e s  w i t h each method o f p r o c e s s i n g . R e g r e s s i n g the p e r c e n t  c o n t e n t o f the p a r t i c l e l e n g t h f r a c t i o n s p a r t i c l e l e n g t h s o f those f r a c t i o n s  nutrient  on the l o g a r i t h m o f the median  gave a b e t t e r f i t than d i d simple  linear  regression.  TABLE X V I : P e r c e n t crude p r o t e i n (CP) and a c i d d e t e r g e n t f i b e r (ADF) c o n t e n t (DM b a s i s ) o f the a l f a l f a (ALF) and h i g h (OGH) and low (OGL) q u a l i t y o r c h a r d g r a s s hay used i n the experiment. HAY ALF b  CP  17.0  ADF  34. l  a-c Means w i t h i n rows w i t h d i f f e r e n t (P < 0.05).  OGL  OGH  b  25. 8  C  5.8  20. 8  a  33. 2  a  b  d i f f e r e n t s u p e r s c r i p t s were s i g n i f i c a n t l y  CO 3 0  w CO  OGH  *o»o.  \  20 c "5 o  CL 10 CD TJ 3  ALF OGL  — • ,  D•  o 0  j  20  40  60  80  P a r t i c l e L e n g t h (mm)  FIGURE 1 2 : P l o t o f t h e average o b s e r v e d v a l u e s and p r e d i c t e d r e g r e s s i o n l i n e s (Y = a + b l o g X ) f o r t h e r e l a t i o n s h i p between crude p r o t e i n c o n t e n t (Y) and p a r t i c l e l e n g t h (X) i n p r o c e s s e d a l f a l f a (ALF) and h i g h (OGH) and low (OGL) q u a l i t y o r c h a r d g r a s s hays.  -74-  ~  .2 « CO XI  50  ALF ®  9  2 40  OGL  fl  Q  •  CD  X)  ii  30  i • —-  I"/*  c CD CO  OGH  L.  CD «-> CD Q JO  20  o  o  <  10  L  20  40  60  80  Particle Length (mm)  FIGURE 13: P l o t o f the average observed v a l u e s and p r e d i c t e d r e g r e s s i o n l i n e s (Y = a + blogX) f o r the r e l a t i o n s h i p between a c i d d e t e r g e n t f i b e r c o n t e n t (Y) and p a r t i c l e l e n g t h (X) i n p r o c e s s e d a l f a l f a (ALF) and h i g h (OGH) and low (OGL) q u a l i t y o r c h a r d g r a s s hays.  -75-  TABLE XVII: R e g r e s s i o n c o e f f i c i e n t s (b) f o r the r e g r e s s i o n * o f p e r c e n t CP and ADF c o n t e n t o f p a r t i c l e l e n g t h f r a c t i o n s on the DM median p a r t i c l e l e n g t h o f the f r a c t i o n f o r the f o r a g e s hammered through a 12.7 mm s c r e e n (H) and chopped a t t h r e e t h e o r e t i c a l l e n g t h s o f c u t (TLC). FORAGE NUTRIENT  CP  ADF  TLC  ALF  H 3.18 6.35 9.53  -9.543 -7.144 -8.359 -8.240  H ' 3.18 6.35 9.53  14.250 10.890 14.510 14.210  OGH c  OGL ab  bc  c  -1.635 * -0.817 * -1.793 0.330 * a  ab  c  a  bc  bc  c  c  -3.033 1.459 0.176 0.233  a  a  a  a  -3.461 -2.872 -2.380 -2.674  * * * *  ab  ab  ab  ab  a  0.700 * 1.840 * 1.230 * 3.860 a  a  ab  Y = a + blogX Means w i t h d i f f e r e n t s u p e r s c r i p t s w i t h i n n u t r i e n t rows were s i g n i f i c a n t l y d i f f e r e n t (P < 0.05). Regression c o e f f i c i e n t not s i g n i f i c a n t l y d i f f e r e n t (P > 0.05).  The r e g r e s s i o n (Y = a + b l o g X ) c o e f f i c i e n t s  from  zero  f o r CP and ADF a r e g i v e n i n  T a b l e XVII. Not a l l o f the r e g r e s s i o n c o e f f i c i e n t s were s i g n i f i c a n t . each f o r a g e , the r e g r e s s i o n c o e f f i c i e n t s significantly affected  f o r CP and ADF c o n t e n t were not  (P > 0.05) by the method o f p r o c e s s i n g t h a t was  The r e g r e s s i o n c o e f f i c i e n t s were n e g a t i v e . T h i s i n d i c a t e d  f o r CP f o r a l l b u t one treatment  t h a t CP c o n t e n t o f the f o r a g e  d e c l i n e d w i t h i n c r e a s i n g p a r t i c l e l e n g t h . The particles  Within  used.  combination  particles  CP c o n t e n t o f f o r a g e  d e c l i n e d a t a s i g n i f i c a n t l y g r e a t e r r a t e (P < 0.05)  with  i n c r e a s i n g p a r t i c l e l e n g t h i n the p r o c e s s e d ALF hay than i t d i d i n the o r c h a r d g r a s s hays.  The r e g r e s s i o n c o e f f i c i e n t s  but not s i g n i f i c a n t l y d i f f e r e n t regression coefficients  f o r CP i n OGL were  (P > 0.05) than those f o r OGH.  f o r CP r e s u l t i n g  -76-  larger,  The  from t h r e e o f the p r o c e s s i n g  methods used on OGH,  however, were not  (P > 0.05), i n d i c a t i n g the  b a s i s of p a r t i c l e The  t h a t CP  from zero  uniformly distributed  f o r ADF  indicating  f o r a l l but  t h a t the ADF  one  treatment  content of  forage  i n c r e a s e d as p a r t i c l e l e n g t h i n c r e a s e d . T h i s i n c r e a s e i n  content with increasing i n p r o c e s s e d ALF  p a r t i c l e l e n g t h was  than i t was  significant difference  OGH  and  OGL,  all  o f the  and, ADF  on  length.  c o m b i n a t i o n were p o s i t i v e  no  i n t h i s f o r a g e was  regression coefficients  particles  significantly different  i n the  between the  e x c e p t i o n o f OGL  regression coefficients  significantly different  from z e r o  (P <  o r c h a r d g r a s s hays. There was,  (P > 0.05)  w i t h the  s i g n i f i c a n t l y greater  hay  ADF 0.05)  however,  regression coefficients chopped a t a TLC  f o r these f o r a g e s were  for  o f 9.53  mm,  not  (P > 0.05).  PARTICLE LENGTH DISTRIBUTIONS  F i t t i n g of the Weibull Function The  coefficients  f u n c t i o n to the CP was  and  ADF  also  i n a l l chopped f o r a g e were c o n s i s t e n t l y  a good f i t o f the  d e t e r m i n a t i o n f o r the  0.97  to 0.99,  Weibull function, and  fitting  o f the  Weibull  i n the f o r the  c o e f f i c i e n t o f s p r e a d (CS) however, r e s u l t e d  gave a b e t t e r f i t to the  d a t a . The  regression  of  cumulative  prediction  o f median p a r t i c l e  Chapter 1).  The  i n a random d i s t r i b u t i o n o f  -77-  There  hammered f o r a g e ranged from  (see  d a t a than d i d the  DM,  lines  coefficients  W e i b u l l f u n c t i o n to the  which i s c o n s i d e r e d low and  o f the  g r e a t e r than 0.99.  around the  f u n c t i o n to the  p a r t i c l e length d i s t r i b u t i o n s  l e n g t h (MPL)  fitting  c u m u l a t i v e p a r t i c l e l e n g t h d i s t r i b u t i o n , by weight, o f  a random d i s t r i b u t i o n o f r e s i d u a l s  indicating  nutrient  o f d e t e r m i n a t i o n f o r the  use  of  the  residuals,  lognormal d i s t r i b u t i o n .  It  was concluded,  t h e r e f o r e , t h a t the f i t o f the W e i b u l l f u n c t i o n t o the  hammermilled f o r a g e d a t a was adequate f o r the p r e d i c t i o n o f MPL and CS i n t h i s exp e r iment.  DM Median P a r t i c l e Length I n most r e s e a r c h i n v o l v i n g the f e e d i n g o f p r o c e s s e d  f o r a g e t o ruminants,  the p a r t i c l e s i z e d i s t r i b u t i o n s o f d i f f e r e n t f o r a g e s , p r o c e s s e d u s i n g the same method, have been assumed t o be s i m i l a r . I n t h i s study, however, t h e r e was a s i g n i f i c a n t  i n t e r a c t i o n (P > 0.05) between the e f f e c t s o f f o r a g e  and method o f p r o c e s s i n g on the DM MPL produced i n the p r o c e s s e d  type  forage  (Table XVIII). Firstly,  the s c r e e n s i z e used i n hammering o r the TLC used i n chopping  TABLE X V I I I : DM, CP and ADF median p a r t i c l e l e n g t h s (mm) o f the f o r a g e s hammered through a 12.7 mm s c r e e n (H) and chopped a t t h r e e t h e o r e t i c a l l e n g t h s o f c u t (TLC). FORAGE NUTRIENT  DM  CP  ADF  * a _  Standard  OGH  OGL  SEM  TLC  ALF  H 3.18 6.35 9.53  4. 7 11. 2cd 10. 9 13. e f  5. 6 8. 6 11. gcde 12. g d e f  8. l b 11. (jcde 14. l 16. 4S  H 3.18 6.35 9.53  3. 7 8. 2 8. 3 10. 3  5. 4^ 8.4 11. d e 12. 6  6. b 8. 5 10. 6 13. l  0.5  H 3.18 6.35 9.53  5. 13. 12. 15.  8. b 11. Qcd 14. e f 16. 2S  0.5  a  C  4  a  a  b  C  C  C  6  e  d  a 2de  9  gde fg 2  a  5. 3 8. 0 11. 0 11. g C d b  C  #  0.6  f  2  C  d  e  2  0  e r r o r o f the mean f o r the v a l u e s i n each n u t r i e n t row.  S Means w i t h d i f f e r e n t s u p e r s c r i p t s w i t h i n n u t r i e n t rows were s i g n i f i c a n t l y d i f f e r e n t (P < 0.05).  -78-  was n o t an a c c u r a t e p r e d i c t o r o f the MPL t h a t was produced when the forages were p r o c e s s e d .  I n every case,  the s c r e e n s i z e  (12.7 mm)  the MPL o f the hammered f o r a g e was l e s s  than  used, w h i l e the MPL o f the chopped f o r a g e was  g r e a t e r than the TLC used d u r i n g chopping.  The n e t r e s u l t was t h a t f o r each  n u t r i e n t , w i t h i n each f o r a g e , hammering through  a 12.7 mm  s i g n i f i c a n t l y s m a l l e r (P < 0.05) MPL than d i d chopping  s c r e e n produced a  a t any TLC.  D i f f e r e n c e s i n the mechanism o f p a r t i c l e s i z e r e d u c t i o n between hammering and chopping TLC  determine the r e l a t i o n s h i p between the s c r e e n s i z e o r  and the MPL produced i n p r o c e s s e d  f o r a g e . The p r o c e s s  o f hammering  forages i n v o l v e s p u l v e r i z a t i o n o f p a r t i c l e s to a s i z e capable  of passing  through  i n the  a g i v e n s i z e o f s c r e e n . Because p u l v e r i z a t i o n r e s u l t s  production of a v a r i a b l e proportion of very small p a r t i c l e s ,  and t h e r e i s a  l i m i t t o the maximum s i z e o f p a r t i c l e which can pass through  the s c r e e n , the  MPL o f hammered f o r a g e w i l l be l e s s than the s i z e o f the s c r e e n a p e r t u r e . When f o r a g e s a r e chopped i n a p r e c i s i o n c u t f o r a g e h a r v e s t e r , however, the MPL o f t h e p r o c e s s e d  f o r a g e i s u s u a l l y g r e a t e r than the TLC (O'Dogherty,  1982) . The c a l c u l a t i o n o f a TLC assumes t h a t p a r t i c l e s e n t e r i n g t h a chopper pass through  the b l a d e s end f i r s t  and p e r p e n d i c u l a r t o the c u t t i n g s u r f a c e .  In p r a c t i c e ,  f o r a g e p a r t i c l e s e n t e r i n g a chopper c a n be randomly o r i e n t e d  w i t h r e s p e c t t o the c u t t i n g s u r f a c e . P a r t i c l e s t h a t do n o t pass through the b l a d e s p e r p e n d i c u l a r t o the c u t t i n g s u r f a c e w i l l be c u t l o n g e r than the TLC. Therefore, used d u r i n g  the MPL o f chopped f o r a g e s u s u a l l y exceeds the c a l c u l a t e d TLC chopping.  P r o c e s s i n g o f the d i f f e r e n t f o r a g e s u s i n g the same methods d i d n o t always r e s u l t i n the p r o d u c t i o n o f s i m i l a r DM MPL between f o r a g e s . There was no  s i g n i f i c a n t d i f f e r e n c e (P > 0.05) i n the DM MPL between ALF and OGH when  the f o r a g e s were hammered o r chopped a t a TLC o f 6.35 and 9.53 mm.  -79-  When OGL  was p r o c e s s e d by the same methods, however, the DM MPL produced was s i g n i f i c a n t l y l a r g e r  (P < 0.05) than t h a t produced  i n each case  when the o t h e r  f o r a g e s were p r o c e s s e d . When the f o r a g e s were chopped a t a TLC o f 3.18  mm,  the r e l a t i o n s h i p between the DM MPL o f the f o r a g e s was changed; t h e r e was no significant difference the MPL produced  (P > 0.05) i n the DM MPL between ALF and OGL whereas  when OGH was chopped was s i g n i f i c a n t l y s m a l l e r (P < 0.05).  With each method o f p r o c e s s i n g , the DM MPL produced was s i g n i f i c a n t l y l a r g e r  when OGL was p r o c e s s e d  (P < 0.05) than t h a t produced  when OGH was  processed. The  reasons  f o r the d i f f e r e n c e s i n the DM MPL between f o r a g e s  by the same method a r e u n c l e a r . Robles geometric mean diameter  processed  e t a l . (1980) found t h a t the  o f ground f o r a g e s g e n e r a l l y i n c r e a s e d w i t h  i n c r e a s i n g c e l l w a l l c o n t e n t o f the f o r a g e s . The h i g h e r ADF c o n t e n t o f OGL as compared w i t h t h a t o f OGH may t h e r e f o r e have c o n t r i b u t e d t o the p r o d u c t i o n o f l a r g e r MPL i n the p r o c e s s e d OGL. The m o r p h o l o g i c a l s t r u c t u r e o f f o r a g e s may a l s o c o n t r i b u t e t o d i f f e r e n c e s i n MPL. Legumes a r e comprised o f l e a v e s and h o l l o w stems which a r e more b r i t t l e components i n g r a s s e s  (Hall et a l . .  than a r e the same  1970). T h e r e f o r e , e s p e c i a l l y when  hammered, p r o c e s s e d legumes s h o u l d produce s m a l l e r MPL than t h a t when g r a s s e s a r e p r o c e s s e d by the same method. F i n a l l y ,  produced  the p r e s e n t a t i o n o f  p a r t i c l e s t o the c u t t i n g s u r f a c e i n a f o r a g e h a r v e s t e r has a d i r e c t  effect  on the l e n g t h o f p a r t i c l e s t h a t a r e produced. S i n c e each f o r a g e was chopped from the b a l e d form, d i f f e r e n c e s between f o r a g e s i n the s t r u c t u r a l c o m p o s i t i o n and o r i e n t a t i o n o f p a r t i c l e s  i n the b a l e s may have c o n t r i b u t e d  to d i f f e r e n c e s i n the DM MPL between d i f f e r e n t f o r a g e s p r o c e s s e d by the same method. No matter what the r e a s o n f o r the p r o d u c t i o n o f d i f f e r e n t MPL i n forages  -80-  p r o c e s s e d by the same method, s m a l l d i f f e r e n c e s between the DM p a r t i c l e o f f o r a g e s f e d t o ruminants  size  have been shown t o have an e f f e c t on r a t e o f  passage, d i g e s t i b i l i t y and chewing b e h a v i o r . S a n t i n i e t a l . (1983) found t h a t d i f f e r e n c e s as s m a l l as 1 mm  i n f o r a g e MPL  d i r e c t l y and  linearly  a f f e c t e d chewing time i n H o l s t e i n cows when they were f e d chopped hay  alfalfa  and s i l a g e . Elimam and Orskov (1984) found t h a t d e c r e a s i n g the Modulus  o f F i n e n e s s o f ground d r i e d g r a s s from 2.77  t o 2.15  reduced  the o u t f l o w o f  Chromium t r e a t e d f i s h meal from the rumen. D e c r e a s i n g the median p a r t i c l e l e n g t h o f chopped hay by a p p r o x i m a t e l y dairy cattle,  decreased  5 mm,  the amount o f time the animals  ruminal acetate:propionate r a t i o  (Van Beukelen  Murphy (1983), when f e e d i n g a l f a l f a hay r e d u c i n g the geometric mean diameter d e c r e a s e d DM  and ADF  when f e d to h i g h p r o d u c i n g  et a l . .  spent chewing and 1985). J a s t e r and  to H o l s t e i n h e i f e r s ,  from 2160  to 1440  the  um  found t h a t  significantly  d i g e s t i b i l i t y b u t not t o t a l chewing times. Osbourn  e t a l . (1981) found t h a t d i f f e r e n c e s as s m a l l as 0.2  i n the moduli  of  f i n e n e s s f o r d i f f e r e n t ground f o r a g e s s i g n i f i c a n t l y a l t e r e d t h e i r O.M.  and  c e l l w a l l d i g e s t i b i l i t y when f e d to lambs. The  d i f f e r e n c e s i n DM MPL  method i n t h i s study ranged  between the f o r a g e s p r o c e s s e d by the same  from 0.5  to 3.5  mm.  These d i f f e r e n c e s i n  MPL  f a l l w i t h i n the range o f s i z e s d i s c u s s e d above t h a t have been shown t o s i g n i f i c a n t l y a f f e c t f o r a g e u t i l i z a t i o n when p r o c e s s e d f o r a g e i s f e d to ruminants.  Therefore, l a c k of q u a n t i f i c a t i o n of forage p a r t i c l e s i z e i n  r e s e a r c h u s i n g d i f f e r e n t f o r a g e s p r o c e s s e d by the same method may u n c o n t r o l l e d e x p e r i m e n t a l e r r o r . The  introduce  above a p p l i e s e q u a l l y to r e s e a r c h  i n v e s t i g a t i n g the e f f e c t o f r e d u c i n g p a r t i c l e s i z e on the ruminant  digestion  p r o c e s s , and to r e s e a r c h i n v e s t i g a t i n g the u t i l i z a t i o n o f d i f f e r e n t s p e c i e s and q u a l i t i e s o f f o r a g e where p r o c e s s i n g i s used  -81-  to reduce  f e e d wastage  and  i n c r e a s e v o l u n t a r y f e e d i n t a k e . The above r e s u l t s , however, c l e a r l y show that with q u a n t i f i c a t i o n o f forage p a r t i c l e s i z e , d i f f e r e n t  processing  methods c a n be u s e d t o produce s i m i l a r MPL i n d i f f e r e n t f o r a g e s reduce u n c o n t r o l l e d e x p e r i m e n t a l The  and thus  error.  above r e s u l t s a l s o showed t h a t d u r i n g chopping, each i n c r e a s e i n TLC  d i d n o t always r e s u l t i n an i n c r e a s e i n the DM MPL o f chopped f o r a g e . When OGL was chopped, t h e r e was a s i g n i f i c a n t i n c r e a s e  (P < 0.05) i n DM MPL w i t h  each i n c r e a s e i n TLC. There was a l s o a s i g n i f i c a n t i n c r e a s e i n DM MPL when the TLC o f ALF was i n c r e a s e d from 6.35 t o 9.35 mm and when t h e TLC o f OGH was i n c r e a s e d from 3.18 t o 6.35 mm.  However, i n c r e a s i n g the TLC o f ALF from  3.18 t o 6.35 mm and the TLC o f OGH from 6.35 t o 9.53 mm d i d n o t r e s u l t i n the p r o d u c t i o n o f s i g n i f i c a n t l y d i f f e r e n t DM MPL (P > 0.05) between the TLC. Therefore,  the p r e p a r a t i o n o f d i e t a r y p a r t i c l e l e n g t h treatments by  chopping, on the b a s i s o f TLC alone, may n o t always ensure t h a t a d i f f e r e n c e e x i s t s between the p a r t i c l e l e n g t h d i s t r i b u t i o n s o f the d i e t a r y  treatments.  CP and ADF Median P a r t i c l e Length As w i t h DM MPL, t h e r e was a s i g n i f i c a n t i n t e r a c t i o n  (P < 0.05) between  the e f f e c t s o f f o r a g e and method o f p r o c e s s i n g on the CP MPL,. and the ADF MPL, produced i n the p r o c e s s e d  f o r a g e . The e f f e c t o f method o f p r o c e s s i n g on  the d i f f e r e n c e s i n DM, CP and ADF MPL w i t h i n each f o r a g e was s i m i l a r f o r each n u t r i e n t t h a t was s t u d i e d . T h e . n u t r i e n t hammered was always s i g n i f i c a n t l y s m a l l e r  MPL produced when a f o r a g e was  (P < 0.05) than t h a t produced when  the f o r a g e was chopped a t any TLC. As w i t h DM MPL, each i n c r e a s e i n the TLC o f chopped OGL r e s u l t e d i n a s i g n i f i c a n t i n c r e a s e  (P < 0.05) i n CP MPL and  ADF MPL; t h e r e was a l s o no s i g n i f i c a n t d i f f e r e n c e (P > 0.05) between the MPL f o r each o f the n u t r i e n t s when ALF was chopped a t a TLC o f 3.18 and 6.35 mm  -82-  and when OGH was chopped a t a TLC o f 6.35 and 9.53 The  mm.  e f f e c t o f method o f p r o c e s s i n g on the d i f f e r e n c e s i n DM, CP and ADF  MPL between f o r a g e s p r o c e s s e d by the same method was d i f f e r e n t w i t h  each  n u t r i e n t t h a t was s t u d i e d , whereas the DM MPL o f ALF and OGH were s i m i l a r when the f o r a g e s were hammered o r chopped a t a TLC o f 6.35 o r 9.53 mm, the CP MPL o f ALF was s i g n i f i c a n t l y s m a l l e r (P < 0.05), and the ADF MPL s i g n i f i c a n t l y l a r g e r (P < 0.05) (except when hammered) than the r e s p e c t i v e n u t r i e n t MPL o f OGH. The DM and the ADF MPL o f OGL were s i g n i f i c a n t l y l a r g e r (P < 0.05) than the r e s p e c t i v e n u t r i e n t MPL o f OGH b u t t h e r e was no s i g n i f i c a n t d i f f e r e n c e (P > 0.05) i n CP MPL between the two f o r a g e s . When OGL and ALF were hammered o r chopped a t a TLC o f 6.35 o r 9.53 mm,  the DM MPL  and CP MPL o f OGL were s i g n i f i c a n t l y l a r g e r (P < 0.05) than the r e s p e c t i v e n u t r i e n t MPL o f ALF; the ADF MPL o f the two f o r a g e s , however, were n o t significantly different  (P > 0.05) w i t h each method o f p r o c e s s i n g ,  except  when the f o r a g e s were hammered. The  d i f f e r e n c e i n the e f f e c t o f the treatment  and ADF MPL produced i n the p r o c e s s e d between f o r a g e s  combinations on the DM, CP  f o r a g e was caused by d i f f e r e n c e s  i n the e x t e n t t h a t n u t r i e n t MPL d e v i a t e d from DM MPL w i t h i n  each f o r a q e . As w i t h p r e v i o u s a n a l y s e s ,  t h e r e was a s i g n i f i c a n t  interaction  between the e f f e c t o f f o r a g e type and the method o f p r o c e s s i n g on the d e v i a t i o n o f CP and ADF MPL from the DM MPL o f the p r o c e s s e d  forage  (Table  X I X ) . With the e x c e p t i o n o f the ADF MPL d e v i a t i o n from t h a t o f DM i n hammered OGH and OGL chopped a t a TLC o f 3.18 mm, o r ADF MPL from t h a t o f DM w i t h i n each p r o c e s s e d  a l l the d e v i a t i o n s o f CP f o r a g e were  significantly  d i f f e r e n t from z e r o . These d e v i a t i o n s r e s u l t e d from the unequal  distribution  o f CP and/or ADF on the b a s i s o f p a r t i c l e l e n g t h w i t h i n each o f the f o r a g e s , as was d i s c u s s e d e a r l i e r . A n e g a t i v e d e v i a t i o n i n d i c a t e d t h a t the n u t r i e n t  -83-  TABLE XIX: D e v i a t i o n between the DM and CP, and DM and ADF median p a r t i c l e l e n g t h s (mm) o f the f o r a g e s hammered through a 12.7 mm s c r e e n (H) and chopped a t t h r e e t h e o r e t i c a l l e n g t h s o f c u t (TLC). FORAGE NUTRIENT  TLC  ALF  H 3.18 6.35 9.53  CP.  e  -1.065 -2.933 -2.694 -3.117  Standard  bc  c  H 3.18 6.35 9.53  ADF  OGH  ab  f  1.169 2.051 1.908S 1.766S h  h  -0.232 -0.280 -0.279 -0.283 -0.239 -0.597 -0.858 -0.934  OGL f  -1.944 -3.392 -3.471 -3.328  f  f  f  c  b  a  a  SEM  *  #  d  0.119  a  a  a  e  0.116 -0.018 * -0.098 -0.150 de  0.058  cd  cd  e r r o r o f the mean f o r the v a l u e s i n each n u t r i e n t row.  Means w i t h d i f f e r e n t s u p e r s c r i p t s w i t h i n n u t r i e n t rows were s i g n i f i c a n t l y d i f f e r e n t (P < 0.05). D e v i a t i o n between ADF and DM MPL n o t s i g n i f i c a n t l y from z e r o (P > 0.05).  was c o n c e n t r a t e d  different  i n the s h o r t e r l e n g t h s o f f o r a g e p a r t i c l e s whereas a  p o s i t i v e d e v i a t i o n i n d i c a t e d t h a t the n u t r i e n t was c o n c e n t r a t e d  i n the  l o n g e r p a r t i c l e s . A d e v i a t i o n t h a t was n o t s i g n i f i c a n t l y d i f f e r e n t from zero i n d i c a t e d t h a t the d i s t r i b u t i o n o f the n u t r i e n t was s i m i l a r t o t h a t o f the DM and t h a t the n u t r i e n t was e v e n l y d i s t r i b u t e d , by weight, throughout the v a r i o u s lengths o f forage  particles.  With a l l t h r e e f o r a g e s , p r o c e s s i n g r e s u l t e d i n a c o n c e n t r a t i o n o f CP i n the s h o r t e r l e n g t h s o f p a r t i c l e s . The method o f p r o c e s s i n g , however, d i d not significantly affect was p r o c e s s e d .  (P > 0.05) the d e v i a t i o n o f CP MPL from DM MPL when OGH  The CP MPL o f ALF and OGL, on the o t h e r hand, d e v i a t e d  s i g n i f i c a n t l y less  (P < 0.05) from the DM MPL when the f o r a g e s were hammered  than i t d i d when the f o r a g e s were chopped. The TLC used d u r i n g chopping d i d not s i g n i f i c a n t l y a f f e c t  (P > 0.05) the d e v i a t i o n o f CP MPL from DM MPL i n  -84-  OGL whereas the d e v i a t i o n w i t h ALF was g r e a t e r (P < 0.05) a t a TLC o f 9.53 mm than i t was when the f o r a g e was chopped a t the two s h o r t e r TLC. There was,  however, no s i g n i f i c a n t d i f f e r e n c e (P > 0.05) i n the d e v i a t i o n o f CP  from DM MPL between ALF chopped a t a TLC o f 3.18 mm and t h a t chopped a t a TLC  o f 6.35  mm.  With the e x c e p t i o n o f ALF chopped a t a TLC o f 9.53 mm,  t h e r e was a  s i g n i f i c a n t d i f f e r e n c e (P < 0.05) i n the d e v i a t i o n o f CP MPL from DM MPL between the t h r e e f o r a g e s w i t h i n each method o f p r o c e s s i n g . The d e v i a t i o n was the g r e a t e s t w i t h OGL, the s m a l l e s t w i t h OGH and i n t e r m e d i a t e w i t h ALF. A t a TLC o f 9.53 mm,  the d i f f e r e n c e i n the d e v i a t i o n o f CP MPL from DM MPL  between ALF and OGL was n o t s i g n i f i c a n t l y d i f f e r e n t  (P > 0.05) . These  d e v i a t i o n s , however, were s i g n i f i c a n t l y g r e a t e r (P < 0.05) than t h a t when OGH was chopped a t a TLC o f 9.53  found  mm.  P r o c e s s i n g had an i n c o n s i s t e n t e f f e c t on the l o c a t i o n o f ADF i n r e l a t i o n to p a r t i c l e l e n g t h between the t h r e e f o r a g e s . The d e v i a t i o n s o f ADF MPL from t h a t o f DM suggest concentrated  t h a t the ADF i n hammered OGL and a l l p r o c e s s e d ALF was  i n the l o n g e r l e n g t h s o f p a r t i c l e s whereas the ADF i n chopped  OGL and a l l p r o c e s s e d OGH was somewhat c o n c e n t r a t e d i n the s h o r t e r p a r t i c l e l e n g t h s . The d e v i a t i o n o f ADF MPL from DM MPL i n ALF and OGH was significantly less  (P < 0.05) when the f o r a g e s were hammered than i t was  when they were chopped. With OGL, the d e v i a t i o n was p o s i t i v e when the forage was hammered and n e g a t i v e when i t was chopped. There was, however, no s i g n i f i c a n t d i f f e r e n c e (P > 0.05) i n the d e v i a t i o n o f ADF MPL from DM MPL between hammered OGL and OGL chopped a t a TLC o f 3.18  mm.  There was a c o n s i s t e n t t r e n d towards a l e s s e r degree o f ADF c o n c e n t r a t i o n i n the l o n g e r p a r t i c l e l e n g t h f r a c t i o n s as the TLC used i n chopping  i n a l l three  forages  i n c r e a s e d . There was, however, no s i g n i f i c a n t  -85-  difference  (P > 0.05) i n the d e v i a t i o n o f ADF MPL from DM MPL between TLC i n  chopped OGL; i n chopped ALF, the p o s i t i v e d e v i a t i o n s i g n i f i c a n t l y  decreased  (P < 0.05) as TLC i n c r e a s e d . The n e g a t i v e d e v i a t i o n o f ADF MPL from DM MPL s i g n i f i c a n t l y i n c r e a s e d (P < 0.05) when OGH was chopped a t a TLC o f 6.35 mm as compared w i t h chopping  a t a TLC o f 3.18 mm;  t h e r e was, however, no  s i g n i f i c a n t change (P > 0.05) i n the d e v i a t i o n when the TLC was i n c r e a s e d from 6.35 t o 9.53  mm.  There was a s i g n i f i c a n t d i f f e r e n c e (P < 0.05) i n the d e v i a t i o n o f ADF MPL from DM MPL between the t h r e e f o r a g e s w i t h i n each method o f p r o c e s s i n g . The  d e v i a t i o n was the l a r g e s t , and p o s i t i v e ,  i n p r o c e s s e d ALF, the s m a l l e s t  and c l o s e t o z e r o i n p r o c e s s e d OGL, and i n t e r m e d i a t e , b u t n e g a t i v e , i n processed  OGH.  The n e g a t i v e d e v i a t i o n o f ADF MPL from t h a t o f DM i n OGH and OGL i n d i c a t e s an o p p o s i t e r e l a t i o n s h i p between n u t r i e n t c o n c e n t r a t i o n and particle  l e n g t h t o t h a t found when p a r t i c l e l e n g t h f r a c t i o n ADF c o n t e n t was  r e g r e s s e d on the MPL o f each f r a c t i o n  (see T a b l e X V I I ) . The p o s i t i v e  r e l a t i o n s h i p seen i n T a b l e XVII would suggest  t h a t t h e r e s h o u l d have been a  p o s i t i v e d e v i a t i o n between the ADF and DM MPL i n the o r c h a r d g r a s s  hays.  There a r e two p o s s i b l e e x p l a n a t i o n s f o r the f i n d i n g o f a n e g a t i v e ADF d e v i a t i o n . Small f l u c t u a t i o n s o c c u r r e d i n the ADF c o n t e n t o f the p a r t i c l e l e n g t h f r a c t i o n s such t h a t some s m a l l e r l e n g t h f r a c t i o n s had a h i g h e r ADF c o n t e n t than d i d some l o n g e r l e n g t h f r a c t i o n s w i t h i n a g i v e n f o r a g e  sample.  I f t h e s h o r t e r l e n g t h , h i g h e r ADF f r a c t i o n c u m u l a t i v e l y c o n t a i n e d more than 50%  o f the sample DM, which d i d occur, a n e g a t i v e d e v i a t i o n c o u l d r e s u l t  when the c u m u l a t i v e  ADF d i s t r i b u t i o n was c a l c u l a t e d . I t seems more p r o b a b l e ,  however, t h a t , c o n s i s t e n t w i t h the r e s u l t s found  i n T a b l e XVII,  t h e r e was no  " a c t u a l " d i f f e r e n c e between the ADF and DM MPL w i t h i n each o f the  -86-  o r c h a r d g r a s s hays.  The n e g a t i v e d e v i a t i o n t h a t was  found c o u l d s i m p l y have  r e s u l t e d from d i f f e r e n c e s i n the f i t t i n g o f the W e i b u l l f u n c t i o n due cumulative  e f f e c t o f v e r y s m a l l d i f f e r e n c e s i n the ADF  to the  c o n t e n t o f the  d i f f e r e n t p a r t i c l e length fractions. In r e s e a r c h i n v e s t i g a t i n g the e f f e c t o f f o r a g e p a r t i c l e s i z e on f o r a g e utilization,  the d i g e s t i b i l i t y o f n u t r i t i o n a l components has  always been  r e l a t e d t o the DM p a r t i c l e s i z e o f the f o r a g e . However, the r e s u l t s o f t h i s study i n d i c a t e t h a t the e f f e c t o f the treatment and ADF  MPL  o f f o r a g e s p r o c e s s e d by the same method was  on which n u t r i e n t was MPL  examined. Furthermore,  o r ADF  to 5.2 MPL  mm.  mm  r e s p e c t i v e l y . I t was  on the DM,  different  from 0.2  CP  depending  the d i f f e r e n c e s i n CP and  between f o r a g e s p r o c e s s e d by the same method ranged  and 0.6  3.5  combinations  ADF  to 3.3  mm  a l s o found t h a t the d e v i a t i o n o f CP  from t h a t o f DM w i t h i n a g i v e n f o r a g e ranged  Some o f these d i f f e r e n c e s i n MPL,  from n e a r l y zero to  as w i t h DM MPL  were i n the range  t h a t has been shown t o a f f e c t r a t e o f passage from the rumen. D i f f e r e n t n u t r i e n t s w i t h i n a g i v e n p r o c e s s e d f o r a g e may o f passage which may  d i r e c t l y a f f e c t the r u m i n a l d i g e s t i b i l i t y o f the  n u t r i e n t . Furthermore d i f f e r e n t CP o r ADF  t h e r e f o r e have d i f f e r e n t r a t e s  d i f f e r e n t f o r a g e s w i t h s i m i l a r DM MPL  MPL  may  have  and v i c e - v e r s a . T h e r e f o r e , the d i g e s t i b i l i t y o f a  g i v e n n u t r i e n t component i n p r o c e s s e d f o r a g e s h o u l d be r e l a t e d to the median p a r t i c l e s i z e o f t h a t n u t r i e n t to a v o i d the i n t r o d u c t i o n o f u n c o n t r o l l e d e x p e r i m e n t a l e r r o r from r e l a t i n g CP o r ADF particle  median  size.  C o e f f i c i e n t s of The  d i g e s t i b i l i t y t o DM  Spread  CS o f a p a r t i c l e l e n g t h d i s t r i b u t i o n  (see Chapter  1) i s a measure of  the r e l a t i v e d i s p e r s i o n o f p a r t i c l e s l e n g t h s around the MPL.  -87-  I t i s possible  f o r two samples o f p r o c e s s e d f o r a g e t o have the same MPL b u t have  different  CS. As the v a l u e o f the CS i n c r e a s e s from 0 to 3.212, the r e l a t i v e d i s p e r s i o n o f p a r t i c l e l e n g t h s decreases d i s t r i b u t i o n becomes l e s s As w i t h MPL,  and the p a r t i c l e  skewed to the r i g h t  (see Chapter 1 ) .  t h e r e was a s i g n i f i c a n t i n t e r a c t i o n  f o r a g e type and method o f p r o c e s s i n g on the DM, p a r t i c l e length distributions XX).  length  between the e f f e c t o f  CP and ADF CS o f the  t h a t were produced d u r i n g p r o c e s s i n g  The s i g n i f i c a n t d i f f e r e n c e s between the CS o f the v a r i o u s  combinations  suggest  t h a t the nature  o f the p a r t i c l e l e n g t h  (Table  treatment  distribution  (eg. normal v s . lognormal) t h a t i s produced by d i f f e r e n t p r o c e s s i n g methods with d i f f e r e n t  f o r a g e s i s n o t c o n s t a n t . These d i f f e r e n c e s i n the n a t u r e o f  the p a r t i c l e l e n g t h d i s t r i b u t i o n may p a r t i a l l y e x p l a i n the observed  lack of  TABLE XX: DM, CP and ADF c o e f f i c i e n t s o f spread o f the f o r a g e s hammered through a 12.7 mm s c r e e n (H) and chopped a t t h r e e t h e o r e t i c a l l e n g t h s o f c u t (TLC). FORAGE NUTRIENT  DM  CP  ADF  Standard e  TLC  ALF  OGH ab  H 3. 18 6. 35 9. 53  1., 0 2 0 1., 0 8 8 1.,138 1..276  H 3. 18 6. 35 9. 53  0..899 1. 0 8 9 1., 0 9 3 1.,183  H 3. 18 6. 35 9. 53  1,, 1 5 7 1,. 1 3 7 1., 2 4 1 1 .375  ab  b  OGL a  0,,954 1.. 0 8 7 1.,344 1,,384°  ab  c  c  a  c d  cd  d  0.. 9 3 5 1,. 1 2 1 1.,337 1,,424  ab  cd  bc  cd  d  a  a b  d  c  b  0 .043  c  d  1., 0 6 6 1. 0 2 0 1..194 1,,417  b c d  a b c  0 .043  e  0.,959 1,. 0 4 7 cd 1, 1,.368 2 8 8  #  d  e  e  bc  1,,301 1,.142 1,,275 1,.524  SEM  d  1,,337 1,, 1 3 8 1,,313 1 .572  bc  0 .047  d  e  e r r o r o f the mean f o r the v a l u e s i n each n u t r i e n t row.  Means w i t h d i f f e r n t s u p e r s c r i p t s w i t h i n n u t r i e n t rows were s i g n i f i c a n t l y d i f f e r e n t (P < 0.05).  -88-  f i t when some p a r t i c l e s i z e d i s t r i b u t i o n s have been f i t t e d t o t h e lognormal d i s t r i b u t i o n (see C h a p t e r l ) . Different  f o r a g e s t h a t had the same MPL when p r o c e s s e d by t h e same  method d i d n o t always have s i m i l a r CS. ALF and OGL h a d s i m i l a r D.M MPL when the f o r a g e s were chopped a t a TLC o f 6.35 mm and s i m i l a r ADF MPL when the f o r a g e s were chopped a t a TLC o f 9.53 mm.  I n b o t h o f these c a s e s , however,  the CS o f OGL was s i g n i f i c a n t l y g r e a t e r (P < 0.05) than t h a t o f ALF. The CP MPL o f OGH and OGL were s i m i l a r when t h e f o r a g e s were chopped a t a TLC o f 6.53 mm whereas t h e CS o f OGH was s i g n i f i c a n t l y g r e a t e r (P < 0.05) than t h a t o f OGL. When ALF and OGH were hammered, s i m i l a r ADF MPL were produced, b u t the CS o f ALF was s i g n i f i c a n t l y g r e a t e r (P < 0.05) than t h a t o f OGL. T h e r e f o r e , even i f s i m i l a r MPL a r e produced i n d i f f e r e n t f o r a g e s by t h e same method, the p a r t i c l e l e n g t h d i s t r i b u t i o n s  processed  o f the processed  f o r a g e s may n o t be s i m i l a r . On t h e o t h e r hand, i n every case where d i f f e r e n t p r o c e s s i n g methods used on the same f o r a g e produced s i m i l a r MPL, the CS o f the p r o c e s s e d  f o r a g e were a l s o n o t s i g n i f i c a n t l y d i f f e r e n t  (P > 0.05).  When each o f t h e f o r a g e s was chopped, a s i g n i f i c a n t i n c r e a s e i n t h e DM, CP o r ADF MPL was accompanied by a s i g n i f i c a n t i n c r e a s e (P < 0.05) i n the CS.  Between f o r a g e s p r o c e s s e d by the same method t h e r e was no c o n s i s t e n t  relationship  between a d i f f e r e n c e i n MPL and a d i f f e r e n c e i n CS. F o r  example, t h e r e was no s i g n i f i c a n t d i f f e r e n c e i n t h e ADF CS o f the t h r e e f o r a g e s when they were chopped a t a TLC o f 3.18 o r 6.35 mm. A t the same TLC, the ADF MPL o f OGH was s i g n i f i c a n t l y s m a l l e r (P < 0.05) than those o f ALF and OGL which were n o t s i g n i f i c a n t l y d i f f e r e n t Conversely,  (P > 0.05) from each o t h e r .  t h e r e was no s i g n i f i c a n t d i f f e r e n c e i n b o t h CP MPL and CP CS  between t h e t h r e e f o r a g e s when they were chopped a t a TLC o f 3.18 mm.  -89-  Finally,  t h e r e were a l s o cases where d i f f e r e n t f o r a g e s p r o c e s s e d by  d i f f e r e n t methods had s i m i l a r MPL b u t had d i f f e r e n t CS. F o r example, the DM MPL o f hammered OGL was n o t s i g n i f i c a n t l y d i f f e r e n t OGH chopped a t a TLC o f 3.18 mm,  (P > 0.05) from t h a t o f  whereas the DM CS o f the OGL was  s i g n i f i c a n t l y s m a l l e r (P < 0.05) than t h a t o f the OGH. The o p p o s i t e was a l s o e v i d e n t i n t h a t d i f f e r e n t f o r a g e s p r o c e s s e d by d i f f e r e n t methods had d i f f e r e n t MPL b u t had s i m i l a r CS. The ADF MPL o f OGL chopped a t a TLC o f 3.18 mm was s i g n i f i c a n t l y l a r g e r  (P < 0.05) than t h a t o f hammered ALF  whereas the CS f o r the two p r o c e s s e d different The  f o r a g e s were n o t s i g n i f i c a n t l y  (P > 0.05).  d i f f e r e n c e s i n the e f f e c t o f treatment  combination  on the DM, CP and  ADF CS, and the d e v i a t i o n o f CP and ADF CS from the DM CS were n o t a n a l y z e d due  t o the confounding  e f f e c t s o f the a s s o c i a t e d changes i n DM, CP and ADF  MPL. F o r the p a r t i c l e l e n g t h d i s t r i b u t i o n s o f a g i v e n f o r a g e , the l e n g t h a t which 100 % c u m u l a t i v e  weight u n d e r s i z e o c c u r s , i s the same f o r a l l t h r e e  nutrient distributions  ( i e ; the l e n g t h o f the l o n g e s t p a r t i c l e  sample).  Because each d i s t r i b u t i o n has the same endpoint,  i n the  a decrease  i n the  MPL o f a n u t r i e n t , due t o a h i g h e r c o n c e n t r a t i o n o f the n u t r i e n t i n the shorter lengths o f p a r t i c l e s , w i l l  r e s u l t i n a s m a l l e r CS f o r t h a t n u t r i e n t  as compared w i t h the DM CS. C o n v e r s e l y ,  an i n c r e a s e i n the MPL o f a  n u t r i e n t , due t o a h i g h e r c o n c e n t r a t i o n o f the n u t r i e n t i n the l o n g e r lengths o f p a r t i c l e s , w i l l compared w i t h the DM CS.  r e s u l t i n a i n c r e a s e d CS f o r t h a t n u t r i e n t as T h e r e f o r e , d i f f e r e n c e s i n the e f f e c t o f f o r a g e and  method o f p r o c e s s i n g on n u t r i e n t CS, and the d e v i a t i o n o f n u t r i e n t CS from the DM CS, a r e a f u n c t i o n o f the d i f f e r e n c e between the DM and n u t r i e n t MPL of  each p r o c e s s e d Although  forage.  i t i s r e c o g n i z e d t h a t the median p a r t i c l e  -90-  s i z e o f processed  f o r a g e can have a d i r e c t e f f e c t on the u t i l i z a t i o n o f f o r a g e s f e d t o ruminants, particle  i t i s s t i l l u n c l e a r as to what e f f e c t the d i s t r i b u t i o n o f  s i z e s around the median has on f o r a g e u t i l i z a t i o n . Moseley  found t h a t DM i n t a k e , disappearance rumen and d r y matter  o f d i g e s t i b l e o r g a n i c matter  f l o w i n the abomasum were more c o n s i s t e n t l y  w i t h the p r o p o r t i o n o f f o r a g e p a r t i c l e s p a s s i n g a 1 mm s o l u b l e d r y matter  (1984)  from the correlated  sieve plus that of  than they were w i t h the geometric mean diameter  o f the  f o r a g e . T h e r e f o r e , d i f f e r e n c e s between f o r a g e s i n the d i s t r i b u t i o n o f p a r t i c l e s i z e s around a common median p a r t i c l e s i z e may have an e f f e c t on forage  utilization.  The r e s u l t s o f t h i s study have shown t h a t f o r DM, different  CP and ADF,  f o r a g e s p r o c e s s e d by the same method may n o t be  Furthermore,  the CS o f  similar.  d i f f e r e n t p r o c e s s e d f o r a g e s t h a t have s i m i l a r MPL may n o t  n e c e s s a r i l y have s i m i l a r CS. T h e r e f o r e , i n the p r e p a r a t i o n o f d i e t a r y treatments  o f p r o c e s s e d f o r a g e , f a i l u r e to e q u a l i z e o r o t h e r w i s e  d i f f e r e n c e s i n CS between treatments, may,  c o n t r o l the  as c o u l d d i f f e r e n c e s i n MPL,  i n t r o d u c e u n c o n t r o l l e d e x p e r i m e n t a l e r r o r i n t o the r e s u l t s o f r e s e a r c h i n which p r o c e s s e d f o r a g e i s f e d .  -91-  SUMMARY  The  study  similar  DM,  different quality screen mm).  length DM, of  forages  and  chopped  effect  at  particle  result  Furthermore, did  not  also given were  of  of  the  These  of  the  same m e t h o d .  hay  were  and method  lengths  distributions that  were  similar  of  rate  between  between  that  passage  DM,  and  has  of  been  and  -92-  and  3.18,  when  high 12.7  6.35  the by  i f  mm  and  9.53  particle comparing  the  spread  (CS)  produced. the  same m e t h o d  CP o r  or  ADF MPL, DM M P L ,  similar  different  MPL o f  different shown  a  c o e f f i c i e n t s of  to  did  or or  CS.  similar There  forages  nutrients  within  significantly some  not  similar  nutrients  different  d i g e s t i b i l i t y of  ruminants.  produced  Alfalfa  (TLC:  similar  MPL o f the  were  determined  and  ADF MPL, the  determine  p r o c e s s i n g on  were  d i d have  CP a n d / o r  same m e t h o d ,  of  that  cut  was  (MPL)  similar  that  differences  the  of  of  to  hammered t h r o u g h  processed using  production  a magnitude  chewing behavior,  distributions  processed forage  differences  processed by were  the  processed forages  always have  forage.  type  particle  forages in  length  orchardgrass  forage  length  significant  forage,  c h a p t e r was u n d e r t a k e n  3 theoretical lengths  CP a n d ADF m e d i a n  always  this  processed by  low q u a l i t y  Different  to  were  distribution  the  in  CP a n d ADF p a r t i c l e  and  The  reported  CS. CS,  were within  a  that a  given  affect  forages  when  fed  CHAPTER I I I  THE  EFFECT OF RATIO ON  FORAGE PARTICLE LENGTH AND FORAGE TO CONCENTRATE INTAKE AND CHEWING BEHAVIOR IN DAIRY CATTLE  INTRODUCTION  Voluntary and  f e e d i n t a k e by  ruminants i s l i m i t e d by  the r a t e o f d i g e s t i o n  the r a t e o f passage o f u n d i g e s t e d f e e d p a r t i c l e s from the rumen.  The  passage o f the p a r t i c l e s i s i n t u r n l i m i t e d to those p a r t i c l e s t h a t have been s u f f i c i e n t l y reduced i n s i z e , by m a s t i c a t i o n rumination,  to a s i z e t h a t i s c a p a b l e o f p a s s i n g  o r i f i c e . R e s e a r c h has  during  eating  through the  shown, however, t h a t the r e d u c t i o n  and  reticulo-omasal  o f the  particle  s i z e i n f e e d s t u f f s f e d to ruminants ( e s p e c i a l l y f o r a g e s ) d e c r e a s e s the  time  r e q u i r e d f o r p a r t i c l e s i z e r e d u c t i o n by  and  increases The  the r a t e o f passage o f d i g e s t a from the rumen (Rode e t a l . . 1985).  p a r t i c l e s i z e o f a f e e d s t u f f , over and  c o n t e n t o f the  feed,  to a d v e r s e l y  a f f e c t i n t a k e by  reduction of p a r t i c l e  decreasing  and  to promote n u t r i t i o n a l d i s o r d e r s  and  l i v e r abscess.  The  excessive  s i z e has  a l t e r i n g rumen  reduction of p a r t i c l e  much o f the r e s e a r c h  ruminant d i g e s t i o n and  forage  been shown  fermentation,  such as r u m i n i t i s , d i s p l a c e d abomasum size is  an almost complete c e s s a t i o n o f r u m i n a t i o n  Unfortunately,  fiber  r a t e o f passage, to reduce f a t  i n the m i l k o f l a c t a t i n g d a i r y cows by  c h a r a c t e r i z e d by  above the c h e m i c a l  i s a l s o important i n p r o v i d i n g p h y s i c a l s t i m u l a t i o n o f  normal rumen f u n c t i o n . E x c e s s i v e  levels  chewing ( S a n t i n i e t a l . . 1983)  activity.  on the e f f e c t s o f p a r t i c l e  u t i l i z a t i o n has  not  involved  size  on  the  q u a n t i f i c a t i o n o f p a r t i c l e s i z e i n the f e e d s t u f f s t h a t were f e d . I d e n t i f i c a t i o n o f the q u a n t i t a t i v e r e l a t i o n s h i p between f e e d s t u f f p a r t i c l e  -93-  s i z e and parameters o f ruminant  d i g e s t i o n i s r e q u i r e d f o r the  maximization  o f f e e d s t u f f u t i l i z a t i o n and the p r e v e n t i o n o f n u t r i t i o n a l d i s o r d e r s . The m o n i t o r i n g o f chewing b e h a v i o r  i s one  o f the s i m p l e s t methods f o r  d e t e r m i n i n g the e f f e c t o f p a r t i c l e s i z e on ruminant u s i n g the method d e s c r i b e d i n Chapter particle  digestion.  Therefore,  1 f o r the q u a n t i f i c a t i o n o f f o r a g e  l e n g t h , the o b j e c t i v e s o f the f o l l o w i n g study were t o :  1. determine  the 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 on the chewing  b e h a v i o r o f l a c t a t i n g d a i r y cows when an o r c h a r g r a s s hay, to two  d i f f e r e n t median p a r t i c l e l e n g t h s , was  to c o n c e n t r a t e  2. determine  f e d a t two  chopped forage  ratios.  the r e l a t i o n s h i p between f o r a g e p a r t i c l e l e n g t h and  chewing b e h a v i o r i n d a i r y s t e e r s f e d a timothy-brome chopped to f o u r d i f f e r e n t median p a r t i c l e l e n g t h s .  -94-  hay  LITERATURE REVIEW  DIGESTION AND  The  PASSAGE OF FEED PARTICLES IN THE  RUMEN  d i s a p p e a r a n c e o f f e e d s t u f f from the rumen can be  processes of d i g e s t i o n , absorption reticulo-omasal  o r i f i c e . The  and  removal by passage through  f e e d p a r t i c l e s i n the r a t i o n . However, not  f r a c t i o n which i s l i m i t e d i n s i z e by  rumen  chemical degradation of  the  a l l components o f f e e d s t u f f s  d e g r a d a b l e by m i c r o b i a l d i g e s t i o n . R e s e a r c h e r s u s i n g t e c h n i q u e s have demonstrated t h a t t h e r e  the  the  m i c r o b i a l d i g e s t i o n o f f e e d s t u f f i n the  i s a c c o m p l i s h e d by m i c r o b i a l attachment to and  i n v i t r o and  the s i z e and  in situ  c o m p o s i t i o n o f the  cell  p o t e n t i a l l y d i g e s t i b l e f r a c t i o n of  f e e d s t u f f s g e n e r a l l y c o n s i s t s o f 90 to 100  % o f the c e l l c o n t e n t  fraction,  o f the c e l l w a l l f r a c t i o n . P a r t o f the p o t e n t i a l l y  d i g e s t i b l e f r a c t i o n i n c l u d e s a rumen f l u i d s o l u b l e f r a c t i o n which does r e q u i r e m i c r o b i a l d e g r a d a t i o n to l e a v e  not  the rumen. P r o d u c t s o f s o l u b l i z a t i o n  and m i c r o b i a l d i g e s t i o n are e i t h e r absorbed through the rumen w a l l , as gases by  are  exists a "potentially digestible"  w a l l f r a c t i o n (Robles e t a l . . 1980). The  plus varying proportions  d e s c r i b e d by  e r u c t a t i o n or p a s s e d from the rumen through the  expelled  reticulo-omasal  o r i f i c e as p a r t o f the f l u i d f r a c t i o n o f the d i g e s t a , or as m i c r o b i a l  cells  attached  the  to f e e d p a r t i c l e s .  rumen due  d i s a p p e a r a n c e o f f e e d s t u f f from  to s o l u b l i z a t i o n and m i c r o b i a l d i g e s t i o n can  % under p r a c t i c a l f e e d i n g The  In t o t a l ,  to about  70  conditions.  u n d i g e s t e d or i n d i g e s t i b l e f r a c t i o n o f i n g e s t e d  the rumen by passage through the r e t i c u l o - o m a s a l however, i s l i m i t e d by  range up  f e e d i s removed from  orifice.  Such passage,  the s i z e o f the p a r t i c l e s . Uden and Van  Soest  (1982)  demonstrated t h a t r e t e n t i o n time o f chromium mordanted f i b e r p a r t i c l e s i n  -95-  the rumen i n c r e a s e d w i t h  i n c r e a s i n g p a r t i c l e s i z e . Poppi e t a l . (1980)  showed t h a t when p a r t i c l e s o f d i g e s t a attempted to l e a v e the rumen t h e r e an i n c r e a s i n g r e s i s t a n c e to passage as the s i z e o f the p a r t i c l e s These r e s e a r c h e r s  found an i n f l e c t i o n p o i n t i n p a r t i c l e s i z e  passage c u r v e s e q u i v a l e n t  to a s i e v e s i z e o f 1.18  that p a r t i c l e s capable of passing probability  through a 1.18  mm mm  increase.  " r e s i s t a n c e " to  f o r sheep. T h i s means s i e v e have a  o f passage than do p a r t i c l e s t h a t w i l l be  higher  r e t a i n e d on a 1.18  s i e v e . They t h e r e f o r e c o n c l u d e d t h a t t h e r e e x i s t e d a c r i t i c a l p a r t i c l e above which passage may was  low.  critical passing  be p o s s i b l e , but  t h a t the p r o b a b i l i t y  Smith e t a l . (1983) a l s o s u p p o r t e d the 1.18  mm  5.3  (.2mm) p a s s e d from the rumen w i t h o u t b e i n g  however, was  2.0  mm)  and  1.0  mm).  o n l y based on r e s u l t s  from one  size.  recovery  p r o p o r t i o n a l to the  reduced i n s i z e . T h e i r work,  animal. Welch and  of polypropylene  from the rumen i n c a t t l e and The  being  a l s o showed t h a t p a r t i c l e s o f n a t u r a l l o g a r i t h i m mean s i z e  measured the passage o f f o u r l e n g t h s and  size  of p a r t i c l e s  to the doudenum would have been r e t a i n e d on a s i e v e o f t h a t  researchers  mm  f o r passage  s i e v e s i z e as  f o r passage i n sheep s i n c e , i n t h e i r work, o n l y 0.2%  The  was  ribbon  three lengths  Smith (1978) (0.5,  i n sheep (0.25,  o f unchewed p a r t i c l e s i n the f e c e s was  l e n g t h o f the p a r t i c l e s . The  1.0,  researchers  1.5 0.5  inversely  a l s o found, i n  b o t h s p e c i e s o f animals, t h a t the l o n g e s t l e n g t h s would pass from the rumen unchewed. T h i s l e n g t h f r a c t i o n , however, o n l y amounted to about 1.0% those p a r t i c l e s p l a c e d The  i n the rumen.  passage o f u n d i g e s t e d  feed residues  from the rumen i s f a c i l i t a t e d  the r e d u c t i o n o f p a r t i c l e s i z e by m i c r o b i a l d e g r a d a t i o n , e a t i n g and al..  ruminating  of  and  d e t r i t i o n from r e t i c u l o - r u m e n  chewing motility  during (Reid et  1977). Once p a r t i c l e s pass from the rumen, t h e r e appears to be  further reduction i n p a r t i c l e size  (Poppi  -96-  e t a l . . 1980;  by  no  Smith e t a l . . 1983).  REDUCTION OF FEEDSTUFF PARTICLE SIZE IN THE RUMEN  M i c r o b i a l Degradation and D e t r i t i o n i n the Rumen M i c r o b i a l d i g e s t i o n has been shown to have a d i r e c t e f f e c t on r e d u c t i o n o f p a r t i c l e s i z e o f f e e d s t u f f s and i n c r e a s i n g the  an i n d i r e c t e f f e c t  the  by  ' b r i t t l e n e s s ' o f d i g e s t a f e e d p a r t i c l e s . Murphy and  (1984) i n c u b a t e d  c o a r s e l y ground a l f a l f a hay  Nicolleti  i n v i t r o f o r 48 h r s and  t h a t a l t h o u g h the median p a r t i c l e s i z e d i d not change, the  log^Q  standard  d e v i a t i o n o f the p a r t i c l e s i z e d i s t r i b u t i o n i n c r e a s e d l i n e a r l y w i t h i n c u b a t i o n . T h i s would i n d i c a t e a u n i f o r m p a r t i c l e s i z e s . When the same hay was  chemical  incubated  degradation  in situ,  found  time o f  of a l l  t h e r e was  a  19%  r e d u c t i o n i n mean p a r t i c l e s i z e a f t e r 96 hours o f i n c u b a t i o n w i t h no  change  i n standard  and  d e v i a t i o n . Welch (1982) i n c u b a t e d  second c u t g r a s s hay  2 cm  a l f a l f a and  stems i n s i t u f o r t e n days and  change i n the p h y s i c a l appearance o f the stems o t h e r brittleness  o b s e r v e d no  first  apparent  than an i n c r e a s e i n the  o f the p a r t i c l e s . T h i s i n c r e a s e i n b r i t t l e n e s s may  have been  r e s p o n s i b l e f o r the r e d u c t i o n o f p a r t i c l e s i z e seen i n s i t u by Murphy Nicollet  and  (1984) by making the p a r t i c l e s more s u s c e p t i b l e to d e t r i t i o n from  rumen movement. Unfortunately,  no  r e s e a r c h has  as y e t been attempted to q u a n t i f y  the  e f f e c t o f rumen movement on comminution o f i n g e s t e d f e e d s t u f f s . A l t h o u g h i t has  been demonstrated t h a t m i c r o b i a l d e g r a d a t i o n  and  d e t r i t i o n from rumen  movement c o n t r i b u t e s d i r e c t l y to p a r t i c l e s i z e r e d u c t i o n i n the rumen, i t i s more l i k e l y increases  t h a t the  increase  in brittleness  from m i c r o b i a l d i g e s t i o n  the e f f e c t i v e n e s s o f p a r t i c l e s i z e r e d u c t i o n by chewing  rumination.  -97-  during  Chewing  Behavior  Chewing d u r i n g e a t i n g and  rumination  i s the p r i m a r y mechanism f o r the  r e d u c t i o n of p a r t i c l e s i z e of undigested the rumen to a s i z e capable The  process  and  indigestible  o f p a s s i n g through the r e t i c u l o - o m a s a l  o f chewing d u r i n g e a t i n g i n v o l v e s p r e h e n s i o n ,  s a l i v a t i o n and  feed residues i n orifice.  mastication,  swallowing. M a s t i c a t i o n d u r i n g e a t i n g s e r v e s  a  triple  purpose. F i r s t l y ,  m a s t i c a t i o n i s r e q u i r e d f o r the r e d u c t i o n o f p a r t i c l e  which, a l o n g w i t h  s a l i v a t i o n , permits  f o o d to be  swallowed. Secondly,  r e d u c t i o n i n p a r t i c l e s i z e i n c r e a s e s the s u r f a c e a r e a o f the p a r t i c l e s which enhances m i c r o b i a l attachment and the rumen. The  m i c r o b i a l d i g e s t i o n and  the  ingested  the r a t e o f d i g e s t i o n i n  s a l i v a t i o n which takes p l a c e d u r i n g e a t i n g i s a l s o  f o r the maintenance o f rumen pH which has  size  important  a d i r e c t e f f e c t on the r a t e o f  reticulo-rumen m o t i l i t y .  F i n a l l y , the r e d u c t i o n o f  p a r t i c l e s i z e d u r i n g e a t i n g i n c r e a s e s the p r o b a b i l i t y  o f d i r e c t passage o f  newly i n g e s t e d p a r t i c l e s from the rumen. Considerable  r e d u c t i o n i n p a r t i c l e s i z e i s a c c o m p l i s h e d by  d u r i n g e a t i n g . R e i d e t a l . (1979) f e d wethers c h a f f e d a l f a l f a (w/w)  DM  chewing i n which  o f the p a r t i c l e s o f f e r e d to the animals were too l a r g e to pass  through a 1 mm  s c r e e n . A f t e r chewing d u r i n g e a t i n g , 52%  p a s s e d through the same s c r e e n . Lee  o f the  particles  and Pearce (1984) found t h a t chewing  d u r i n g e a t i n g i n s t e e r s reduced the p r o p o r t i o n o f p a r t i c l e s r e t a i n e d on 1 mm  97%  s c r e e n by  30  to 40 p e r c e n t .  s i z e o f i n g e s t e d f e e d was  In terms o f Modulus o f F i n e n e s s ,  reduced by 46  to 52 p e r c e n t .  particle  There i s , however, a  great v a r i a t i o n  i n the e x t e n t  to which animals reduce p a r t i c l e s i z e  eating  Pearce, 1984;  Gill  (Lee and  during  e t a l , 1966).  I t appears t h a t the e x t e n t o f comminution r e q u i r e d d u r i n g e a t i n g may l i m i t e d to t h a t r e q u i r e d f o r b o l u s  a  formation  -98-  and  lubrication prior  to  be  swallowing.  Welch and Smith (1978) found t h a t 99% o f one  centimeter  long  p a r t i c l e s o f p o l y p r o p y l e n e r i b b o n were r e c o v e r e d unchewed i n the rumen o f a f i s t u l a t e d s t e e r f e d a mixture  o f the r i b b o n and c o n c e n t r a t e s . B a l c h (1958)  found t h a t the r a t e o f f e e d i n g e s t i o n , weight o f s a l i v a produced  and r a t e of  s a l i v a t i o n d u r i n g e a t i n g were not c o n s i s t e n t w i t h a l l types o f f e e d s t u f f s . Hay,  which had a l a r g e r p a r t i c l e s i z e and a h i g h e r l e v e l o f f i b e r ,  consumed a t a f a s t e r r a t e than was  was  c o n c e n t r a t e . Swallowed b o l u s e s o f hay  c o n t a i n e d 12-16% d r y matter whereas those o f c o a r s e l y ground c o n c e n t r a t e s c o n t a i n e d 35-40% d r y matter. of  s a l i v a was  C a l c u l a t i o n s r e v e a l e d t h a t 3-4  s e c r e t e d per u n i t weight o f hay  times  consumed as compared w i t h  c o n c e n t r a t e s . On the o t h e r hand, the r a t e o f s a l i v a s e c r e t i o n  was  approximately  The  doubled when the animals were f e d c o n c e n t r a t e s .  d i f f e r e n c e s i n b o l u s d r y matter  c o n t e n t was  the amount  caused by a more r a p i d  r a t e o f the c o n c e n t r a t e s as compared w i t h t h a t o f hay.  Therefore,  p a r t i c l e s i z e and r e s i s t a n c e t o p a r t i c l e s i z e r e d u c t i o n may  ingestion initial  have a  r e g u l a t i n g e f f e c t on e a t i n g r a t e . Although,  the amount o f comminution o c c u r r i n g d u r i n g e a t i n g may  l i m i t e d to t h a t r e q u i r e d to enable swallowing,  be  the r e d u c t i o n o f p a r t i c l e  s i z e d u r i n g e a t i n g d i r e c t l y enhances the passage o f p a r t i c l e s  from  the  rumen. B a i l y and B a l c h (1961) s t u d i e d the e f f e c t o f chewing d u r i n g e a t i n g on the removal o f p a r t i c u l a t e matter times o f a cow  f e d hay n o r m a l l y , or by placement o f hay  rumen through a f i s t u l a . with " f i s t u l a who  from the rumen by comparing the  Time spent r u m i n a t i n g was  d i r e c t l y into  50%  e t a l . (1981)  time spent e a t i n g per kg o f c e l l w a l l i n t a k e  a s s o c i a t e d w i t h i n c r e a s e d time spent  the  i n c r e a s e d by c l o s e to  f e e d i n g " . These r e s u l t s were s u p p o r t e d by Bae  found t h a t d e c r e a s e d  rumination  was  ruminating.  P a r t i c l e s i z e r e d u c t i o n and s a l i v a t i o n from chewing d u r i n g r u m i n a t i o n ,  -99-  as w i t h e a t i n g ,  i s important f o r enhancing m i c r o b i a l d i g e s t i o n . However,  chewing d u r i n g r u m i n a t i o n i s the f i n a l and most important mechanism f o r the r e d u c t i o n o f p a r t i c l e s i z e e n a b l i n g passage reticulo-omasal  from the rumen through  the  orifice.  The e s s e n t i a l i t y o f r u m i n a t i o n f o r the passage has been c l a s s i c a l l y demonstrated m u z z l i n g i n sheep.  Pearce and M o i r  of undigested p a r t i c l e s  by the p r e v e n t i o n o f r u m i n a t i o n by (1964) found t h a t p r e v e n t i o n o f  r u m i n a t i o n i n c r e a s e d r e t e n t i o n times and s u b s e q u e n t l y i n c r e a s e d DM,  OM  and  crude f i b e r apparent d i g e s t i b i l i t i e s . However, m u z z l i n g d i d n o t c o m p l e t e l y i n h i b i t p a r t i c u l a t e passage  from the rumen, which l e a d the r e s e a r c h e r s to  c o n c l u d e t h a t m i c r o b i a l d i g e s t i o n must account f o r a s u b s t a n t i a l degree p a r t i c l e s i z e r e d u c t i o n . U n f o r t u n a t e l y , complete was  of  prevention of rumination  n o t a c c o m p l i s h e d by the muzzles which meant t h a t the e f f e c t o f the  p r e v e n t i o n o f r u m i n a t i o n may a c c o m p l i s h e d complete  have been u n d e r e s t i m a t e d . Welch (1982)  prevention of rumination using steers. At  each  f e e d i n g , the animals had a c c e s s to hay f o r 2 hours a f t e r which they were muzzled u n t i l the next f e e d i n g p e r i o d . Intake o f hay was  markedly  m u z z l i n g . Towards the end o f the f e e d i n g p e r i o d s , the muzzled p r e f e r r e d t o ruminate  r a t h e r than e a t . I n another t r i a l ,  animals d i e o f esophageal to ruminate w h i l e  reduced by  animals  the r e s e a r c h e r had  and pharynx i m p a c t i o n when the animals  attempted  muzzled.  T h e r e f o r e , f a c t o r s t h a t a f f e c t the d i s a p p e a r a n c e o f f e e d s t u f f from the rumen, e i t h e r by a f f e c t i n g d i g e s t i b i l i t y or r a t e o f passage reticulo-omasal o r i f i c e ,  through  the  a l s o a f f e c t the chewing b e h a v i o r o f the a n i m a l . For  t h i s r e a s o n , B a l c h (1971) proposed  the use o f the t o t a l time spent chewing  ( e a t i n g p l u s r u m i n a t i o n ) as an index o f the f i b r o u s n e s s o f f e e d s t u f f s f e d to ruminants.  -100-  FACTORS AFFECTING CHEWING BEHAVIOR  Feedstuff The  Particle  Size  r e d u c t i o n o f p a r t i c l e s i z e i n f e e d s t u f f s f e d to ruminants has  e f f e c t on the r a t e o f f e e d i n g e s t i o n , r a t e and d i g e s t i o n , chewing b e h a v i o r and  extent  an  of microbial  r a t e o f passage o f d i g e s t a p a r t i c l e s from  the rumen. A change i n the r a t e o f passage o f p a r t i c l e s from the rumen i n t u r n has  an e f f e c t on the s i t e o f f e e d s t u f f d i g e s t i o n i n the  gastro-intestinal It  tract.  i s w e l l documented t h a t the r e d u c t i o n o f p a r t i c l e s i z e o f f e e d s t u f f s  can be  a s s o c i a t e d w i t h an i n c r e a s e  1984). T h i s e f f e c t , however, has species  and m a t u r i t i e s o f f o r a g e .  Campling and  Freer  d r i e d grass hay  i n voluntary  been shown not  p e l l e t i n g oat straw i n c r e a s e d  intake  for  Freer  i n t a k e by  increases The exert  screen.  and  (Weston and  and p e r c e n t  T h i s c o r r e l a t i o n , however, was  and  i n the  of p a r t i c l e s  not  significant  the e f f e c t o f p a r t i c l e s i z e r e d u c t i o n e f f e c t with high  quality  an i n c r e a s i n g e f f e c t when the f i b r o u s n e s s  on  forages  o f the  feed  Kennedy, 1984).  r e d u c t i o n of p a r t i c l e s i z e of forages  i t s g r e a t e s t e f f e c t by  particles  significantly  compared w i t h f e e d i n g  the modulus o f f i n e n e s s  a l l feeds t e s t e d . In general,  concentrates  d i d not  artificially  (1966) found t h a t g r i n d i n g  26%  i n c r e a s i n g i n t a k e appears to have l i t t l e and  hay  and  Pearce (1984) found s i g n i f i c a n t c o r r e l a t i o n s between the  o f some f e e d s and  r e t a i n e d on a 1 mm  Kennedy,  consistent for a l l  (1966) found t h a t c o a r s e g r i n d i n g o f an  or a medium q u a l i t y r y e g r a s s  and  to be  (Weston and  For example, Campling e t a l . (1963)  a f f e c t i n t a k e . However, Campling and  l o n g form. Lee  intake  f e d to ruminants appears to  i n c r e a s i n g the r a t e o f passage o f  from the rumen. Campling and  Freer  -101-  digesta  (1966) found t h a t g r i n d i n g  of  r y e g r a s s hay d i d n o t s i g n i f i c a n t l y i n c r e a s e v o l u n t a r y f e e d i n t a k e but s i g n i f i c a n t l y d e c r e a s e d the r e t e n t i o n time o f s t a i n e d p a r t i c l e s rumen. The r e d u c t i o n i n r e t e n t i o n time was  i n the  also associated with a  c o n s i d e r a b l e r e d u c t i o n i n the e x t e n t o f d i g e s t i o n . I n the same study, g r i n d i n g o f o a t straw a l s o s i g n i f i c a n t l y reduced the r e t e n t i o n time o f particles  i n the rumen and the d i g e s t i b i l i t y o f the f o r a g e . 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 was, d i f f e r e n c e may  however, n o t as pronounced  as w i t h the hay d i e t .  This  have been due t o the s m a l l e r s i z e o f the p o t e n t i a l l y  d i g e s t i b l e f r a c t i o n t h a t i s n o r m a l l y found i n straws as compared w i t h t h a t found i n g r a s s hays. The e f f e c t o f f e e d s t u f f p a r t i c l e s i z e on the p r o c e s s o f d i g e s t i o n i n ruminants has been shown t o be r e f l e c t e d i n the chewing b e h a v i o r o f the a n i m a l s . As e a r l y as 1935, particle  K i c k and Gerlaugh  (1935) showed t h a t r e d u c i n g the  s i z e o f good q u a l i t y a l f a l f a hay by chopping and g r i n d i n g  reduced  the amount o f time s t e e r s spent e a t i n g and r u m i n a t i n g and was  associated  w i t h a d e c r e a s e d r e t e n t i o n time o f d i g e s t a i n the rumen. T h i s  effect,  however, was  significant  n o t c o n s i s t e n t over a l l t r e a t m e n t s . There was  no  d i f f e r e n c e i n the amount o f time spent chewing between a hay f e d i n the l o n g form and t h a t chopped t o an e s t i m a t e d median l e n g t h o f 24.7 o f time spent chewing 6.4  mm  d e c l i n e d when the f o r a g e was  mm.  The amount  chopped to a p p r o x i m a t e l y  i n l e n g t h and then d e c l i n e d f u r t h e r when the f o r a g e was  ground.  f e e d i n g o f ground hay a l s o caused a marked amount o f p s e u d o - r u m i n a t i o n i n d i c a t e d t h a t the f o r a g e had l o s t i t s a b i l i t y t o s t i m u l a t e rumination  The which  normal  activity.  S i n c e the work o f K i c k and G e r l a u g h (1935), the m a j o r i t y o f the r e s e a r c h on the e f f e c t o f p a r t i c l e s i z e on chewing b e h a v i o r has p r e d o m i n a n t l y used q u a l i t a t i v e treatments i n v o l v i n g the f e e d i n g o f f o r a g e i n the l o n g ,  -102-  coarsely  chopped and  ground form or j u s t the l o n g and  t h i s r e s e a r c h have i n g e n e r a l (1935) i n t h a t t h e r e  s u p p o r t e d the r e s e a r c h  appears to be no  time spent chewing when f o r a g e i n the  ground forms. The  r e s u l t s of  o f K i c k and  s i g n i f i c a n t reduction  Gerlaugh  i n the amount o f  i s c o a r s e l y chopped as compared w i t h  l o n g form (eg. K i c k e t a l . . 1937;  Gordon, 1958  ) and  that  s i g n i f i c a n t l y reduces b o t h the amount o f time spent e a t i n g and Gordon, 1958;  F r e e r and  grinding  ruminating  ( K i c k e t a l . . 1937;  Balch,  Campling and  1966).In many cases the f i n e g r i n d i n g o f f o r a g e s  Freer,  1952;  feeding  Campling,  1965;  to an almost complete c e a s s a t i o n o f normal r u m i n a t i o n a c t i v i t y and  has  led  a marked  occurrence of pseudo-rumination. Therefore,  the p a r t i c l e s i z e o f f e e d s t u f f s i s important i n s t i m u l a t i n g  normal r u m i n a t i o n a c t i v i t y . The w a l l by  need f o r p h y s i c a l s t i m u l a t i o n o f the rumen  d i g e s t a p a r t i c l e s i n promoting normal r u m i n a t i o n has  c l a s s i c a l l y demonstrated. B a l c h i n a cow  f e d ground hay  (1952) r e s t o r e d normal r u m i n a t i o n  i n normal r u m i n a t i o n  when l a c t a t i n g cows were f e d a l f a l f a meal p e l l e t s and  introduced forage  rumination.  the  activity  concentrates.  Normal  grams o f p o l y p r o p y l e n e r i b b o n  (1952) found t h a t a l t h o u g h g r i n d i n g  the l a c k o f p h y s i c a l s t i m u l u s  was  of  always i n h i b i t the t r i p l e c o n t r a c t i o n o f the r e t i c u l u m  d u r i n g normal r u m i n a t i o n , caused by  r e s t o r e d when 200  i n t o the d i e t . B a l c h  d i d not  activity  by p l a c i n g a b r i s t l e b r u s h i n the r e t i c u l u m o f  a n i m a l . Welch (1982) found a l a r g e r e d u c t i o n  r u m i n a t i o n a c t i v i t y was  been  seen  o f the rumen w a l l  g r i n d i n g i n h i b i t e d the r e g u r g i t a t i o n r e f l e x r e q u i r e d f o r normal The  same l a c k o f s t i m u l u s  has  p r e d o m i n a n t l y comprised o f c o n c e n t r a t e s 1965).  -103-  a l s o been seen when d i e t s  have been f e d .  ( F r e e r and  Campling,  Level of Intake As  d i s c u s s e d above, most f e e d s t u f f s c o n t a i n a f r a c t i o n t h a t i s not  p o t e n t i a l l y d i g e s t i b l e i n the rumen. T h e r e f o r e , amount o f i n d i g e s t i b l e m a t e r i a l t h a t must be  as i n t a k e  increases,  c l e a r e d from the rumen a l s o  i n c r e a s e s . Subsequently, i n c r e a s e d i n t a k e r e s u l t s i n an i n c r e a s e animals spend e a t i n g and time spent e a t i n g and Welch and  ruminating,  r e l a t i o n s h i p between i n t a k e  however, i s not  to 1000  grams i n 250  by o n l y 67%.  i n c r e a s e between the 750  and  Increasing  gram i n t e r v a l s gave a  s i g n i f i c a n t l i n e a r increase i n rumination 1000  i n t a k e l e v e l s remained the same but maximum o f 1800  grams per day,  a non-linear  about one  increased.  Bae  and  intake  incremental half  the  grams to a  the animals were f e d c o n t i n u o u s l y , time w i t h  the  increments between  i n t a k e s ranged from 250  increase i n rumination  amount o f r u m i n a t i o n  increase  s i n g l e meal  time. However, the  gram i n t a k e s was  on  statistically  d i f f e r e n c e between the lower i n t a k e l e v e l s . When the  was  intake  grams f e d as a s i n g l e meal, i n c r e a s e d  time the animals spent r u m i n a t i n g to 1000  and  constant.  time i n sheep p r e v i o u s l y f a s t e d f o r 48 h o u r s . A 100%  i n t a k e , from 500  from 250  The  i n time  Smith (1969b) s t u d i e d the e f f e c t o f i n c r e a s i n g hay  the r u m i n a t i o n i n hay  ruminating.  the  increased intake;  per kg o f i n t a k e s u b s e q u e n t l y d e c r e a s e d as  e t a l . (1981) a l s o found t h a t r u m i n a t i o n  there the  intake  time per kg  intake  decreased with  i n c r e a s i n g l e v e l o f i n t a k e when dry H o l s t e i n cows were f e d  hay  100,  a t 50,  75,  and  125  % o f d a i l y NRC  recommended dry m a t t e r i n t a k e  and  r e s u l t s were e x p r e s s e d as chewing time per kg o f c e l l w a l l i n t a k e . However, a t the h i g h e r  l e v e l s o f i n t a k e the cows s i g n i f i c a n t l y i n c r e a s e d  chewing r a t e d u r i n g r u m i n a t i o n i n time spent r u m i n a t i n g .  The  which may researchers  of c e l l w a l l intake increased with  their  have compensated f o r the  reduction  a l s o found t h a t e a t i n g time per  i n c r e a s i n g i n t a k e . Subsequently the  -104-  kg  total  time chewing p e r kg c e l l w a l l i n t a k e d i d n o t d i f f e r s i g n i f i c a n t l y w i t h  level  o f i n t a k e . Bae e t a l . (1981) c o n c l u d e d t h a t t h e i r r e s u l t s i n d i c a t e d t h a t i n g e s t e d roughages r e q u i r e d a c o n s t a n t a c t i o n o f e a t i n g and The  increase  amount o f comminution by the combined  rumination.  i n time spent chewing d u r i n g e a t i n g , p e r kg o f i n t a k e ,  with  i n c r e a s e d l e v e l s o f i n t a k e may be due t o a decrease i n i n t a k e and an increase Gill  i n chewing a c t i v i t y p e r b o l u s  swallowed towards the end o f a meal.  e t a l . (1966) s t u d i e d the e a t i n g b e h a v i o r  and p a r t i c l e  size of  swallowed hay i n d a i r y c a t t l e f e d a t two l e v e l s o f i n t a k e . As i n t a k e i n c r e a s e d from 5 t o 7.5 kg p e r day, t h e r e was an i n c r e a s e  i n the time spent  e a t i n g from 15.4 t o 18.3 min p e r kg o f i n t a k e . I n c r e a s i n g  the amount o f f e e d  o f f e r e d p e r meal d i d n o t s i g n i f i c a n t l y a f f e c t the chewing r a t e p e r minute but  i n c r e a s e d the number o f chews p e r b o l u s  swallowed. The r e s e a r c h e r s  also  found t h a t w i t h b o t h l e v e l s o f i n t a k e , the number o f chews p e r b o l u s i n c r e a s e d and the r a t e o f b o l u s Gill  swallowing d e c r e a s e d as the meal  progressed.  e t a l . (1966) a l s o found t h a t a h i g h e r number o f chews p e r b o l u s  swallowed d u r i n g e a t i n g was a s s o c i a t e d w i t h a reduced mean p a r t i c l e s i z e i n the swallowed  boluses.  Therefore,  i n c r e a s i n g the l e v e l o f i n t a k e  r e q u i r e d t o consume the f e e d w h i l e  i n c r e a s e s the amount o f time  the i n c r e a s e d number o f chews p e r b o l u s  swallowed and d e c r e a s e d r a t e o f swallowing as a meal p r o g r e s s e s  causes an  increase  i n e a t i n g time p e r kg o f i n t a k e . However, the g r e a t e r r e d u c t i o n i n  particle  size associated with  i n c r e a s e d time spent e a t i n g r e s u l t s i n a  d e c r e a s e d requirement f o r time spent r u m i n a t i n g l e v e l of intake chewing b e h a v i o r  p e r kg o f i n t a k e as the  i n c r e a s e s . Due t o the e f f e c t s o f changes i n i n t a k e l e v e l on d e s c r i b e d above, r e s u l t s from experiments, where i n t a k e  l e v e l s between animals a r e n o t e q u a l , must be a n a l y z e d  -105-  on the b a s i s o f the  t o t a l amount o f chewing a c t i v i t y t h a t o c c u r s p e r kg o f i n t a k e .  Chemical The  Composition  of Feedstuff  amount o f time animals  spend r u m i n a t i n g i s r e l a t e d t o the amount o f  u n d i g e s t e d f e e d r e s i d u e i n the rumen. Welch and Smith (1968) found t h a t immediately  a f t e r the removal o f f e e d from sheep b e i n g f a s t e d t h e r e was a  r a p i d d e c l i n e i n r u m i n a t i o n a c t i v i t y which f e l l Examination  t o z e r o a f t e r 36 hours.  o f rumen c o n t e n t s o f a s a c r i f i c e d sheep showed t h a t the rumen  contents contained i n s u f f i c i e n t f i b r o u s constituents r e q u i r e d f o r s t i m u l a t i o n o f r u m i n a t i o n . Upon r e f e e d i n g , normal r u m i n a t i o n  commenced  w i t h i n 24 h o u r s . T h e r e f o r e any f a c t o r d i r e c t l y a f f e c t i n g the d i g e s t i b i l i t y of  f e e d s t u f f s i n the rumen w i l l have a d i r e c t e f f e c t on the amount o f time  spent  ruminating.  The  c h e m i c a l c o m p o s i t i o n and the s i z e o f the p o t e n t i a l l y  digestible  f r a c t i o n o f f e e d s t u f f s has been shown t o be the most important d e t e r m i n i n g the r a t e o f d i g e s t a disappearance al..  1981). S i n c e the c e l l  (Fonnesbeck e t a l . .  factor  from the rumen (Fonnesbeck e t  c o n t e n t s o f f e e d s t u f f approach 100% d i g e s t i b i l i t y  1981), the s i z e and c o m p o s i t i o n o f the f i b e r  fraction  appear t o c o n t r o l the l e v e l o f u n d i g e s t e d r e s i d u e s i n the rumen and, t h e r e f o r e , has an e f f e c t on the amount o f time an animal spends r u m i n a t i n g . Robles  e t a l . (1981) f e d mature wethers o r c h a r d g r a s s hay which v a r i e d i n  c e l l w a l l c o n t e n t from 60 t o 78 p e r c e n t . These r e s e a r c h e r s found t h a t as c e l l w a l l c o n c e n t r a t i o n i n c r e a s e d , DM and DE i n t a k e , and DM  digestibility  and e x c r e t i o n r a t e d e c r e a s e d w h i l e c e l l w a l l i n t a k e , rumen volume and rumen c e l l w a l l c o n t e n t and r e t e n t i o n time i n c r e a s e d s i g n i f i c a n t l y . found t h a t on d i f f e r e n t d i e t s ,  the animals  ate to a constant  They a l s o indigestible  c e l l w a l l i n t a k e . An i n c r e a s e i n c e l l w a l l i n t a k e and i n c r e a s e d r e t e n t i o n  -106-  time w i t h f e e d s t u f f s o f i n c r e a s i n g c e l l w a l l c o n t e n t has been shown to i n c r e a s e amount o f time spent r u m i n a t i n g . Welch and Smith (1969a) f e d sheep e a r l y - c u t o r c h a r d g r a s s hay, cut  mixed a l f a l f a g r a s s hay,  and 5.4 crude  l a t e c u t mixed grass hay,  weedy oat straw,  and oat straw c o n t a i n i n g 22.8,  p e r c e n t crude p r o t e i n and 27.1,  36.4,  39.2,  28.3,  8.0,  7.3,  and 42.9  2nd 17.8  percent  f i b e r r e s p e c t i v e l y . They found t h a t the simple c o r r e l a t i o n between  r u m i n a t i o n time and f o r a g e c e l l w a l l i n t a k e was  0.99  whereas the  c o r r e l a t i o n between r u m i n a t i o n time and crude p r o t e i n i n t a k e was  simple only  0.24.  T h e r e f o r e , as the d i g e s t i b i l i t y o f a r a t i o n i s i n c r e a s e d , the amount o f residue remaining  t o be c l e a r e d from the rumen d e c r e a s e s which has  e f f e c t on r e d u c i n g the amount o f time spent The  f i b r o u s n e s s o f f e e d s t u f f s may  b e h a v i o r i n ruminants.  a direct  ruminating.  a l s o have an e f f e c t on the e a t i n g  F r e e r e t a l . (1962) found t h a t F r i e s i a n and  Shorthorn  c a t t l e r e q u i r e d more time to e a t oat straw than they d i d to e a t hay.  Balch  (1971) a l s o found t h a t l e s s f i b r o u s f e e d s t u f f s r e q u i r e d s i g n i f i c a n t l y time t o be consumed by c a t t l e than d i d h i g h e r f i b e r f e e d s . Lee and  less  Pearce  (1984) demonstrated t h a t d i f f e r e n t f o r a g e s r e q u i r e d d i f f e r e n t g r i n d i n g e n e r g i e s t o produce the same modulus o f f i n e n e s s and was  r e l a t e d t o the ADF  maximum p a r t i c l e  size,  t h a t g r i n d i n g energy  c o n t e n t o f the f o r a g e . I f swallowing  i s l i m i t e d by a  f e e d s t u f f s t h a t are more r e s i s t a n t t o comminution  would r e q u i r e l o n g e r chewing times d u r i n g e a t i n g . The m o i s t u r e behavior. G i l l  c o n t e n t o f f e e d s t u f f s may  a l s o have an e f f e c t on e a t i n g  e t a l (1966) found t h a t a l t h o u g h t h e r e was  d i f f e r e n c e i n e a t i n g time p e r kg DM  i n t a k e , t h e r e was  no  significant  a s i g n i f i c a n t increase  in  the number o f chews per minute, and a s i g n i f i c a n t decrease  of  chews p e r b o l u s swallowed d u r i n g e a t i n g when f r e s h herbage was  c a t t l e as compared w i t h the f e e d i n g o f the f o r a g e as a hay.  -107-  i n the number f e d to  Feeding of f r e s h  c u t herbage a l s o i n c r e a s e d the r a t e o f b o l u s swallowing o f the b o l i .  The  d r y weights o f the b o l i from the two  and  f e d i n the f r e s h form, as opposed to a hay,  s i z e o f the swallowed b o l i  i n c r e a s e d from 1314  p a r t i c l e s i z e o f the b o l i d i d not decrease when the hay was  um  weight  d i e t s , however, were  not s i g n i f i c a n t l y d i f f e r e n t . These r e a s e r c h e r s a l s o found r y e g r a s s was  the wet  t h a t when mature the median p a r t i c l e  to 2070 um  and  the  as the meal p r o g r e s s e d as i t d i d  fed.  Forage to Concentrate Ratio I t has been shown t h a t an i n c r e a s e i n the f o r a g e to c o n c e n t r a t e r a t i o i n a r a t i o n i s a s s o c i a t e d w i t h an i n c r e a s e i n the amount o f time spend chewing d u r i n g e a t i n g and r u m i n a t i n g 1975). C o n c e n t r a t e s  ( B a l c h , 1958;  ruminants  Sudweeks e t a l . .  g e n e r a l l y c o n t a i n l e s s f i b e r than do f o r a g e s . T h e r e f o r e ,  an i n c r e a s e i n the f o r a g e to c o n c e n t r a t e r a t i o o f a r a t i o n r e s u l t s i n an i n c r e a s e i n f i b e r i n t a k e and  the l e v e l o f i n d i g e s t i b l e r e s i d u e s i n the  rumen. As d i s c u s s e d above, such an i n c r e a s e i n the f i b e r c o n t e n t o f r a t i o n s n o r m a l l y causes an i n c r e a s e i n the amount o f time the animals and r u m i n a t i n g . The p a r t i c l e s i z e o f c o n c e n t r a t e s a l s o tends than t h a t o f most f o r a g e s . As the p r o p o r t i o n o f f o r a g e i n the i n c r e a s e s , the p a r t i c l e s i z e o f the d i e t i n c r e a s e s and, requirement  lower  requirement  p r o p o r t i o n of concentrates  eating behavior concentrates  smaller  diet  t h e r e f o r e , the  f o r comminution o f  i s r e f l e c t e d i n the h i g h e r r a t e o f passage o f c o n c e n t r a t e s  the rumen as compared w i t h t h a t o f f o r a g e s The  to be  f o r comminution o f p a r t i c l e s by chewing d u r i n g e a t i n g and  r u m i n a t i o n a l s o i n c r e a s e s . The concentrates  spend e a t i n g  o f ruminants.  Balch  the r e c o r d i n g s had  (Rode e t a l . . 1985) .  i n a r a t i o n a l s o has (1958) found  an e f f e c t on  t h a t when animals  the  ate  a wavy appearance i n d i c a t i n g the mouth  -108-  from  was  not opened wide; hay b a s e l i n e . The  e a t i n g gave a more r e g u l a r p a t t e r n w i t h a l e v e l  r a t e o f jaw movements when e a t i n g c o n c e n t r a t e s  somewhat h i g h e r  (88-90 per min)  than t h a t f o r hay  was  (72-82 p e r min).  chewing r a t e s d i d not s i g n i f i c a n t l y change d u r i n g the course  Particle The  also These  o f a meal.  Density s p e c i f i c g r a v i t y of p a r t i c l e s  e f f e c t on the s e l e c t i o n  of p a r t i c l e s  i n the rumen appears to have a f o r rumination  and passage from  rumen. Evans e t a l . (1973) found t h a t i n c a t t l e f e d p a s t u r e hay, commenced a t the time o f maximum c o n c e n t r a t i o n o f low minimum c o n c e n t r a t i o n o f h i g h d e n s i t y p a r t i c l e s  maximum and  rumination and  i n the rumen. Rumination density  low d e n s i t y p a r t i c l e s were a t a minimum  c o n c e n t r a t i o n i n the rumen. S i n c e particles  the  density p a r t i c l e s  a c t i v i t y t h e n c e a s e d a t the p o i n t where the c o n c e n t r a t i o n o f h i g h p a r t i c l e s was  direct  the i n c r e a s e i n s p e c i f i c g r a v i t y o f f e e d  i n the rumen i s l i k e l y a r e s u l t o f m i c r o b i a l d i g e s t i o n and  hydration of feed p a r t i c l e s  (Hooper and Welch, 1985)  i t i s possible that  d i f f e r e n c e s i n the r a t e o f change o f the s p e c i f i c g r a v i t y o f d i f f e r e n t w i l l have an e f f e c t on the time a f t e r Welch and diets  feeding that rumination  Smith (1969a) found t h a t the peak r u m i n a t i o n  of v a r y i n g n u t r i t i o n a l composition  depending on the d i e t  occured  1.1  to 1.2  fastest  commences.  time i n sheep f e d  at d i f f e r e n t  times  fed.  Passage from the rumen, once p a r t i c l e s i z e appears to be  feeds  i s s u f f i c i e n t l y reduced,  f o r p a r t i c l e s with s p e c i f i c g r a v i t i e s  ( K i n g and Moore, 1957;  Campling and  i n the range o f  F r e e r , 1962). Hooper  Welch (1985) found t h a t the s p e c i f i c g r a v i t y o f f o r a g e s  and  increased at a  g r e a t e r r a t e when immersed i n rumen f l u i d than i t d i d when the f o r a g e immersed i n water. These r e s e a r c h e r s  a l s o found t h a t f o r a g e p a r t i c l e s  -109-  was in  b u f f e r s o l u t i o n i n c r e a s e d i n s p e c i f i c g r a v i t y a t a f a s t e r r a t e than d i d particles  i n water. Thomson e t a l . (1977) found t h a t the a d d i t i o n o f  s a l i v a r y s a l t s to the rumen i n c r e a s e d the l i q u i d d i l u t i o n r a t e . s a l i v a t i o n during rumination p a r t i c l e s and  may  Therefore,  i n c r e a s e the s p e c i f i c g r a v i t y o f comminuted  i n c r e a s e the r a t e o f passage o f these p a r t i c l e s .  I t i s not known, however, whether the s p e c i f i c g r a v i t y o f f e e d s t u f f s w i l l a f f e c t the amount o f comminution p a r t i c l e s w i l l r e q u i r e b e f o r e  passage  i s p o s s i b l e . I t i s l i k e l y t h a t the s p e c i f i c g r a v i t y o f f e e d s t u f f s w i l l have its  g r e a t e s t e f f e c t on the passage o f p a r t i c l e s a l r e a d y r e d u c e d to a  capable of passing  through the r e t i c u l o - o m a s a l  o r i f i c e . Therefore,  size  the  s p e c i f i c g r a v i t y o f f e e d s t u f f s would p r o b a b i l i t y e x e r t a g r e a t e r e f f e c t rumen f i l l spend  and  on  the l e v e l o f i n t a k e r a t h e r than on the amount o f time animals  ruminating.  Body Weight Bae  e t a l . (1983) found t h a t chewing time per kg o f c e l l w a l l i n t a k e i n  d i f f e r e n t breeds o f d a i r y c a t t l e s i g n i f i c a n t l y d e c r e a s e d w i t h metabolic  body weight; d i f f e r e n c e s i n body weight a c c o u n t e d f o r 52%  variability  of  i n time spent chewing between a n i m a l s . D i f f e r e n c e s i n c e l l  i n t a k e between animals accounted f o r an a d d i t i o n a l 22%  of v a r i a b i l i t y .  o f animal d i d not s i g n i f i c a n t l y a f f e c t chewing time over and e f f e c t o f body s i z e . There was speed o f chewing. Lea and  a l s o no  g r i n d i n g a c t i o n may  above  Pearce (1984) h y p o t h e s i z e d  that  -110-  wall Breed  and  anatomical  movement, t e e t h a r e a  and  account f o r d i f f e r e n c e s i n p a r t i c l e s i z e r e d u c t i o n  feed.  the  the  c o r r e l a t i o n between body s i z e  d i f f e r e n c e s i n the animal i n mouth s i z e , jaw  ingested  increasing  of  METHODS OF MONITORING CHEWING BEHAVIOR  As w i t h most b e h a v i o r a l s t u d i e s , the most complete i n f o r m a t i o n on chewing b e h a v i o r Unfortunately,  i s o b t a i n a b l e by v i s u a l o b s e r v a t i o n and  recording.  the amount o f i n f o r m a t i o n r e q u i r e d i n chewing s t u d i e s ,  i n c l u d i n g t o t a l times  of d i f f e r e n t behaviors  chews, makes t h i s t a s k almost i m p o s s i b l e o b s e r v a t i o n o f even one being designed  animal  animal  and  the c o u n t i n g o f  to be accomplished  a t a time.  S i n c e many o f the  individual  by the  visual  experiments  today to study the e f f e c t s o f v a r i o u s d i e t a r y treatments  chewing b e h a v i o r  r e q u i r e simultaneous  the manpower requirements v i s u a l observation chewing b e h a v i o r  and  (Penning,  o b s e r v a t i o n o f a number o f  animals,  the c o s t o f t h a t l a b o r p r o h i b i t the use  of  1983). Furthermore, v i s u a l o b s e r v a t i o n o f  can become t e d i o u s and  i n a c c u r a c i e s i n the r e c o r d e d  on  tiring,  resulting i n errors  i n f o r m a t i o n ( C a s t l e e t a l . . 1975). To  and overcome  the d i f f i c u l t i e s o f v i s u a l o b s e r v a t i o n , a number o f automated methods have been developed  to r e c o r d the jaw movements o f animals.  o b s e r v a t i o n o f chewing b e h a v i o r  accurate  r e q u i r e s the development and use  these methods s i n c e none are commercially developed  The  a v a i l a b l e . Any  o f one  method t h a t i s  s h o u l d i d e a l l y s a t i s f y the f o l l o w i n g c r i t e r i a :  1: be a c c u r a t e  i n the r e c o r d i n g o f chewing a c t i v i t y , making i t  p o s s i b l e to d i s t i g u i s h between chewing a c t i v i t y i n v o l v e d i n e a t i n g and r u m i n a t i o n drinking, licking,  and  and non-chewing a c t i v i t y such as bawling.  2: r e q u i r e a minimum o f l a b o r and/or s u p e r v i s i o n d u r i n g r e c o r d i n g and a n a l y s i s o f d a t a .  -Ill-  of  3: be e a s i l y i n t e r c h a n g e a b l e between animals and v e r y r e s i s t a n t to damage by animal a c t i v i t y and o t h e r o p e r a t i o n a l  failure.  4: be e a s i l y c o n s t r u c t e d a t a minimum o f expense.  5: be a d a p t a b l e t o t e l e m e t r y or o t h e r remote r e c o r d i n g t o enable o b s e r v a t i o n o f g r a z i n g and e a t i n g i n a l l forms o f animal confinement  and h o u s i n g .  6: be a d a p t a b l e t o e l e c t r o n i c a n a l y s i s o f r e c o r d e d d a t a by l o g g e r s and  The  computers.  e a r l i e s t method o f automatic chewing m o n t i t o r i n g u t i l i z e d  expandable  rubber tube which was  the animal  (Johnstone-Wallace,  tube was pen was  data  an  p l a c e d under the jaw o r over the nose o f  1953;  O l t j e n et a l . .  1962).  The  expandable  then connected v i a another tube to a p r e s s u r e tambour on which a mounted. Jaw movements by the animal would s t r e t c h the rubber  which was  tube  p l a c e d around the jaw c a u s i n g an i n c r e a s e i n p r e s s u r e i n the  c l o s e d system which i n t u r n moved the r e c o r d i n g pen. B a l c h (1971) d e s i g n e d a s i m i l a r system but used a l i g h t l y i n f l a t e d tube made from t h i n w a l l e d rubber t u b i n g s u p p o r t e d on a p e r f o r a t e d b r a s s tube t o p r e v e n t problems o f k i n k i n g . T h i s d e v i c e was  used b o t h to monitor jaw movement when p l a c e d beneath  the  cheek s t r a p o f a l e a t h e r head s t a l l and r e t i c u l o - r u m e n m o t i l i t y when anchored  i n the rumen. A c t i v i t y i n c r e a s e d the p r e s s u r e i n the c l o s e d  system  by d e c r e a s i n g the volume o f the d e v i c e , s i m i l a r to the s q e e z i n g o f a b a l l o o n . P r e s s u r e changes were r e c o r d e d by movement o f the tambour pen on a moving c h a r t r e c o r d e r . A l t h o u g h the above systems have been used  -112-  successfully,  they s u f f e r from the need f o r animals to be  partially  r e s t r a i n e d t o p r e v e n t k i n k i n g o f the tube which connects the jaw d e v i c e t o the tambour, and from temperature changes which a l s o  pneumatic  alter  p r e s s u r e i n the system thus r e n d e r i n g i t n o n - f u n c t i o n a l . The problems w i t h the above system have been overcome w i t h the use o f p r e s s u r e t r a n s d u c e r s which e l i m i n a t e the need f o r a c o n n e c t i n g l e n g t h o f tube (Law and Sudweeks, 1975). P r e s s u r e impulses from a pneumatic converted to e l e c t r i c a l  d e v i c e are  impulses which can be r e c o r d e d on an e l e c t r o n i c  moving c h a r t r e c o r d e r . These r e s e a r c h e r s found t h a t t h e i r system o p e r a t e d w i t h l e s s t h a n 1/2  p e r c e n t e r r o r over the range o f 1/4  t o 16 impulses per  second. The use o f e l e c t r o n i c t r a n s d u c e r s a l s o enables remote chewing a c t i v i t y on tape by r a d i o  recording of  telemetry.  G r a z i n g b e h a v i o r has been s t u d i e d u s i n g V i b r i c o r d e r s which  record  movement by the motion o f a pendulum which i s r e c o r d e d on a c i r c u l a r d i s k o f paper by a pen a t t a c h e d t o the pendulum ( C a s t l e e t a l . .  1975). T h i s  system  a l o n e , however, can o n l y d i s c e r n animal motion a s s o c i a t e d w i t h body movement d u r i n g g r a z i n g . Ruckebush  and Bueno (1973) ( c a t t l e ) and Bechet  (1978)  (sheep) removed the pendulum from a V i b r i c o r d e r and adapted a pneumatic c o n t r o l t o the pen which r e c e i v e d impulses from a rubber b u l b s i t u a t e d i n the submandibular space o f the g r a z i n g a n i m a l . T h i s l a t t e r method improved the a c c u r a c y o f r e c o r d i n g w i t h V i b r i c o r d e r s ,  i n c r e a s e d the amount o f  i n f o r m a t i o n r e c o r d e d and d i d not r e q u i r e the use o f e x p e n s i v e t e l e m e t r y when used w i t h g r a z i n g a n i m a l s . Another form o f t r a n s d u c e r r e c o r d e r has been employed  which  c o m p l e t e l y removes the need f o r pneumatics. L e v e i l l e e t a l . (1979) developed a v a r i a b l e i n d u c t i o n gauge by w i n d i n g copper w i r e around a l e n g t h o f tube, f l a t t e n i n g the tube and w i r e , and c o v e r i n g the assembly w i t h a polymer t o  -113-  protect i t .  The  t r a n s d u c e r was  mounted around the nose band on sheep  to the mounting o f pneumatic tubes. E l e c t r i c a l impulses r e s i s t a n c e i n the t r a n s d u c e r due  (1983) developed  i d e n t i c a l system except t h a t the t r a n s d u c e r was  t r a n s d u c e r was  caused by changes i n  to jaw movement were i n t e r p r e t e d by a d a t a  l o g g e r and a n a l y z e d by computer. Penning  tube w i t h carbon g r a n u l e s and  similar  an  almost  made by p a c k i n g a  i m p l a n t i n g e l e c t r o d e s a t each end.  mounted i n a s i m i l a r manner w i t h the impulses  silicon The  recorded  on  tape and l a t e r a n a l y z e d by a m i c r o p r o c e s s o r . Chewing b e h a v i o r has  a l s o been r e c o r d e d w i t h o u t  u s i n g v a r i o u s forms o f microswithches and Cowper, 1972;  Chambers e t a l . .  the need f o r pneumatics  (Duckworth and S h i r l a w , 1955;  Stobbs  1981). These types o f "event r e c o r d e r s "  a r e mounted d i r e c t l y under the jaw and a c t i v a t e d by d i r e c t p r e s s u r e or mounted on a h a l t e r and a c t i v a t e d by a c h a i n o r rope s l u n g under the jaw the a n i m a l . M i c r o s w i t c h impulses, however, r e c o r d o n l y a s i n g l e amplitude  o f t h i s type o f system i s c r i t i c a l ;  to the m i c r o s w i t c h can a l s o be a major problem (P.M. communication). T h i s method a l s o g i v e s no the jaw movements which are important activities  fixed  s t r o k e when the jaw o f the animal opens f a r enough to a c t i v a t e  s w i t c h . T h e r e f o r e , the adjustment  such as bawling,  of  the  damage  Kennedy, p e r s o n a l  i n f o r m a t i o n on the amplitude  i n i d e n t i f y i n g many non  of  chewing  l i c k i n g and d r i n k i n g . Both the i n c l u s i o n o f  these a c t i v i t i e s as chewing and any damage t o the m i c r o s w i t c h c o u l d introduce considerable error. Two  methods f o r d i r e c t measurement o f jaw movement and chewing b e h a v i o r  have been developed.  N i c h o l s (1966) a t t a c h e d s p e c i a l e l e c t r o d e s to the  masseter muscles o f sheep. Changes i n the e l e c t r i c a l p o t e n t i a l r e c e i v e d from the s k i n over the muscles were a m p l i f i e d by a t r a n s m i t t e r which r e l a y e d the s i g n a l s t o a r e c e i v e r which r e c o r d e d the s i g n a l s on an e l e c t r i c c h a r t  -114-  r e c o r d e r . Kydd and M u l l i n s (1963) developed a method f o r f i t t i n g a v e r y small pressure  transducer  t o a t o o t h and c o n n e c t i n g  embedded i n a t o o t h borne p a r t i a l denture.  i t to a t r a n s m i t t e r  T h i s method would have a g r e a t  advantage i n t h a t the a c t u a l g r i n d i n g energy and chewing a c t i v i t y c o u l d be measured d i r e c t l y .  However, use o f b o t h o f the above methods on a l a r g e  s c a l e i s l i m i t e d by the d i f f i c u l t y  o f f i t t i n g the t r a n s d u c e r s ,  the l a c k o f  easy i n t e r c h a n g e a b i l i t y between animals and the c o s t o f animal p r e p a r a t i o n .  -115-  MATERIALS AND  DAIRY COW  METHODS  TRIAL  Twelve H o l s t e i n d a i r y cows, a l l i n mid to  f o u r d i e t a r y treatments  i n a b a l a n c e d two p e r i o d changeover d e s i g n  and Magee, 1976). Each animal r e c e i v e d two experiment.  The  chopped t o two two  l a c t a t i o n , were randomly a l l o t t e d  d i e t a r y treatments  o f the f o u r treatments  comprised  d u r i n g the  good q u a l i t y o r c h a r d g r a s s  d i f f e r e n t median p a r t i c l e l e n g t h s (10 mm  forage to concentrate r a t i o s  (Gill  and 20 mm)  (40:60 and 60:40) i n a two by two  arrangement; the cows were f e d ad l i b i t u m i n two meals p e r day.  hay  fed at factorial  Each f o u r  week e x p e r i m e n t a l p e r i o d c o n s i s t e d o f t h r e e weeks a d a p t a t i o n f o l l o w e d by week o f sample  one  collection.  D u r i n g the a d a p t a t i o n p e r i o d , the cows were housed w i t h the r e s t o f the h e r d i n a f r e e s t a l l b a r n but f e d i n d i v i d u a l l y u s i n g e l e c t r o n i c a l l y a c t i v a t e d doors. A t the b e g i n n i n g o f the sampling p e r i o d , s i x o f the cows on t r i a l were t r a n s f e r r e d to the r e s e a r c h a r e a f o r e l e c t r o n i c m o n i t o r i n g o f chewing b e h a v i o r  (see F i g u r e 14). The  animals were adapted  24 hours a f t e r which chewing b e h a v i o r was h o u r s . The  monitored  to stanchions f o r  c o n t i n u o u s l y f o r 24  cows were then r e t u r n e d t o the f r e e s t a l l b a r n f o r the next  a d a p t a t i o n p e r i o d and the second  group o f s i x cows was  r e s e a r c h a r e a . Chewing m o n i t o r i n g commenced immediately  t r a n s f e r r e d to the f o l l o w i n g the  a f t e r n o o n m i l k i n g and t e r m i n a t e d j u s t p r i o r t o the next a f t e r n o o n m i l k i n g . D u r i n g the e a r l y morning o f each m o n i t o r i n g p e r i o d , i t was  necessary  f o r the  cows t o be r e l e a s e d from the s t a n c h i o n s to p e r m i t p a r l o r m i l k i n g . Any chewing a c t i v i t y t h a t o c c u r r e d d u r i n g t h a t time was D u r i n g the sampling p e r i o d , m i l k , rumen f l u i d ,  -116-  monitored  visually.  and f e c a l samples were a l s o  FIGURE 14: D a i r y c a t t l e i n s t a n c h i o n s t a l l s the m o n i t o r i n g o f chewing b e h a v i o r .  -117-  i n research area  during  taken t o be a n a l y z e d i n r e l a t i o n t o o b j e c t i v e s o f another  trial.  DAIRY STEER TRIAL  Three H o l s t e i n s t e e r s i n i t i a l l y A y r s h i r e s t e e r weighing treatments  776  weighing  845,  947  and 927 kg and  kg were randomly a l l o c a t e d to f o u r d i e t a r y  i n a b a l a n c e d L a t i n Square d e s i g n . Each animal had  s u r g i c a l l y p r e p a r e d w i t h rumen and duodenal cannulae  been  f o r the t a k i n g o f  samples t o be a n a l y z e d i n r e l a t i o n t o o t h e r o b j e c t i v e s o f the t r i a l . d i e t a r y treatments  c o n s i s t e d o f timothy-brome hay  median p a r t i c l e l e n g t h s (5.0, 10.0,  15.0,  60:40 f o r a g e t o c o n c e n t r a t e r a t i o a t 9.5 weight p e r day. at  The  6 hour i n t e r v a l s ,  one  The  chopped t o f o u r d i f f e r e n t  and 20.0  mm)  which were f e d i n a  kg per 100 kg o f m e t a b o l i c body  r a t i o n s were f e d i n f o u r e q u a l a l l o t m e n t s d u r i n g the s t a r t i n g a t 9:00  AM.  Each e x p e r i m e n t a l p e r i o d was  day  21  days i n l e n g t h w i t h 14 days f o r d i e t a d a p t a t i o n f o l l o w e d by 7 days o f sample c o l l e c t i o n d u r i n g which chewing b e h a v i o r was  monitored.  The  s t e e r s were  housed i n s t a n c h i o n s i n the r e s e a r c h a r e a d e s c r i b e d above f o r the d u r a t i o n of  the experiment  the f i r s t  w i t h the e x c e p t i o n o f the f i r s t  10 days o f a d a p t a t i o n i n  two p e r i o d s d u r i n g which the s t e e r s were housed u n r e s t r a i n e d i n  i n d i v i d u a l pens. Chewing m o n i t o r i n g commenced immediately PM for  f e e d i n g on the morning o f the second 48  sampling  p r i o r to the  3:00  day and r a n c o n t i n u o u s l y  hours.  PREPARATION OF CHOPPED FORAGE  All  the f o r a g e t h a t was  f e d i n the two  experiments  above was  w i t h e i t h e r a John Deere Model 35 o r a Fox f o r a g e h a r v e s t e r . The  -118-  chopped forage  was  obtained i n standard two strand or three wire square bales which were randomly a l l o c a t e d into dietary treatments p r i o r to chopping. Randomly selected test bales were chopped, using various machine settings, into an open fronted b i n . Each test sample of chopped hay was  then subsampled and  separated on the Forage P a r t i c l e Separator (see Chapter 1) to determine the median p a r t i c l e length. Appropriate machine settings were then selected to prepare chopped forage of the required median p a r t i c l e lengths f o r use as dietary treatments  i n the  experiments.  MONITORING OF CHEWING BEHAVIOR  The development of a chewing monitor system was  required to enable  continuous monitoring of the chewing behavior of the animals on t r i a l . This system was  i n s t a l l e d i n a separate research f a c i l i t y i n which the animals on  t r i a l were held i n i n d i v i d u a l stanchions (Figure 14). The system consisted of a pneumatic device (Figure 15) which was held i n place under the jaw of the animal by a s p e c i a l l y designed h a l t e r (Figure 16). The h a l t e r s were adjustable i n three places (over the nose, behind the pohl, and under the neck) to enable correct p o s i t i o n i n g of the pneumatic device. Pressure impulses generated by jaw movements were transmitted v i a a length of tygon tubing to a " s i l i c o n chip" electronic pressure transducer (Figure 17) mounted between the ears of the animal on the pohl strap of the h a l t e r (Figure 16). E q u i l i b r a t i o n of s t a t i c pressure i n the closed pneumatic system was achieved by a c t i v a t i o n of the a i r valve mounted on the r i g h t hand side of the pneumatic device. The pressure transducer was  connected v i a a quick coupler e l e c t r i c a l  connector and an expandable cord to an amplifier which was mounted on the  -119-  FIGURE 15: Pneumatic d e v i c e o f the chewing m o n i t o r f o r p r o d u c i n g p r e s s u r e impulses from jaw movement.  -120-  FIGURE 16: Chewing monitor t r a n s d u c e r mounted.  h a l t e r w i t h pneumatic d e v i c e and  -121-  pressure  FIGURE 17: Chewing monitor " s i l i c o n c h i p " p r e s s u r e mounted i n i t s s t e e l housing.  -122-  transducer  stanchion support d i r e c t l y  above the animal's head. T h i s method o f  c o n n e c t i o n a l l o w e d u n r e s t r i c t e d movement o f the animal's head and  easy  d i s c o n n e c t i o n t o r e l e a s e the animals to go to the m i l k i n g p a r l o r .  The  a m p l i f i e r was  "hard-wired" t o a s p e c i a l power s u p p l y and t o a v a r i a b l e  speed  c h a r t r e c o r d e r on which output t r a c i n g were r e c o r d e d . Both the a m p l i f i e r  and  power s u p p l y were d e s i g n e d and c o n s t r u c t e d by G i l l e s G a l z y , S e n i o r T e c h n i c i a n o f the Department o f Animal  Science, U n i v e r s i t y of B r i t i s h  Columbia. D u r i n g the m o n i t o r i n g o f chewing b e h a v i o r , animal a c t i v i t y was  also  v i s u a l l y m o n i t o r e d u s i n g c l o s e d c i r c u i t v i d e o equipment. T r a c i n g s r e c o r d e d on the c h a r t r e c o r d e r were s i m u l t a n e o u s l y compared w i t h the animal  activity  seen on the v i d e o m o n i t o r s to ensure a c c u r a t e r e c o r d i n g o f chewing b e h a v i o r .  ANALYSIS OF CHEWING RESULTS  D u r i n g each chewing m o n i t o r i n g p e r i o d , each one hour segment o f r e c o r d e d d a t a was  collated into total  r e m a i n i n g time was  times spent e a t i n g and r u m i n a t i n g .  The  c l a s s i f i e d as i d l i n g , which i n c l u d e d time spent  drinking,  b a w l i n g , and grooming, a l l o f which were d i s c e r n a b l e from the t r a c i n g s .  The  number o f b o l u s e s t h a t were r e g u r g i t a t e d d u r i n g p e r i o d s o f r u m i n a t i o n were a l s o c a l c u l a t e d from the t r a c i n g s . The chewing a c t i v i t i e s f o r each hour r e c o r d i n g were then t o t a l l e d as t o t a l  f o r the e n t i r e r e c o r d i n g p e r i o d and  of  expressed  time p e r 24 hours. These times were then d i v i d e d by the d r y matter  i n t a k e f o r each animal to g i v e the time spent chewing and i d l i n g p e r k i l o g r a m o f i n t a k e as was  suggested by B a l c h (1971) as an index o f the  f i b r o u s n e s s o f f e e d s t u f f s . Time chewing p e r b o l u s r e g u r g i t a t e d  was  c a l c u l a t e d by d i v i d i n g the t o t a l time spent r u m i n a t i n g by the number o f  -123-  b o l u s e s r e g u r g i t a t e d d u r i n g a twenty f o u r hour p e r i o d .  STATISTICAL ANALYSIS  The  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 f o r a g e t o c o n c e n t r a t e r a t i o on  parameters o f chewing b e h a v i o r was t e s t e d by G e n e r a l L i n e a r H y p o t h e s i s the BMD:10V packaged program o f t h e U n i v e r s i t y o f B r i t i s h Columbia. v a r i a b l e s were e x p r e s s e d  using  Yield  as chewing a c t i v i t y p e r kg o f DM i n t a k e w i t h -  m e t a b o l i c body weight ( B W ^ ) i n c l u d e d i n t h e a n a l y s i s as a c o v a r i a b l e . D i f f e r e n c e s between means f o r t h e treatment  combinations  were t e s t e d by  Duncan's M u l t i p l e Range T e s t ( a = 0.05).  The G e n e r a l L i n e a r H y p o t h e s i s  Y  ijklm =  where:  u + A  Yij i  + Pj + L  k  + H  X  + LH  k l  + bBw  i j k l m  +  E  i  j  k  l  m  =  t h e dependent v a r i a b l e : chewing  u  =  t h e o v e r a l l mean  Ai  =  t h e e f f e c t o f the i ' t h a n i m a l .  Pj  =  the e f f e c t o f the j ' t h p e r i o d .  L  k  =  the e f f e c t o f t h e k ' t h f o r a g e median p a r t i c l e length.  Hi  =  t h e e f f e c t o f the I ' t h f o r a g e : c o n c e n t r a t e ratio.  =  the e f f e c t o f t h e i n t e r a c t i o n between the k ' t h f o r a g e median p a r t i c l e l e n g t h and t h e I'th forage to concentrate r a t i o .  k  m  LH i k  b B W  ±  f o r the D a i r y cow t r i a l was as f o l l o w s :  ijklm  parameters.  the e f f e c t o f t h e c o v a r i a b l e m e t a b o l i c body weight  -124-  ^ijklm  =  t  b  e  unexplained r e s i d u a l error a s s o c i a t e d w i t h each sample.  The G e n e r a l L i n e a r H y p o t h e s i s  Y  ijk  -  where: Y ^ j  f o r the D a i r y S t e e r t r i a l was  u + A i + Pj + L  k  + bBw  i j k  +  E  i  j  k  =  the dependent v a r i a b l e : chewing parameter.  u  =  the o v e r a l l mean.  A^  =  the e f f e c t o f the i ' t h animal.  Pj  =  the e f f e c t o f the j t h p e r i o d .  L  =  the e f f e c t o f the k ' t h f o r a g e median p a r t i c l e length.  =  the e f f e c t o f the c o v a r i a b l e m e t a b o l i c body weight.  =  the u n e x p l a i n e d r e s i d u a l e r r o r a s s o c i a t e d w i t h each sample.  k  k  bBWij  E^j  k  k  1  -125-  as f o l l o w s :  RESULTS  DAIRY COW  TRIAL  The p a r t i c l e l e n g t h d i s t r i b u t i o n s  o f the two median chop l e n g t h s o f  forage  f e d i n t h i s experiment are shown i n T a b l e XXI. The median  length  (MPL) o f the s h o r t chopped f o r a g e was  smaller  (P < 0.05)  chop  mm which was  significantly  than t h a t o f the l o n g chopped f o r a g e which had a median  p a r t i c l e l e n g t h o f 18.06 mm. chop f o r a g e  7.32  particle  (1.284) was  The c o e f f i c i e n t o f spread  (CS) o f the s h o r t  a l s o s i g n i f i c a n t l y s m a l l e r than t h a t f o r the l o n g  (1.488). The h i g h e r CS f o r the l o n g chop i n d i c a t e d t h a t i t had a  r e l a t i v e l y narrower d i s t r i b u t i o n o f p a r t i c l e l e n g t h s which were a l s o more normally  distributed.  There was no s i g n i f i c a n t d i f f e r e n c e (P > 0.05)  i n nutritional  TABLE XXI: P a r t i c l e l e n g t h d i s t r i b u t i o n (% sample wt.) and d i s t r i b u i o n parameters o f the s h o r t and l o n g chopped o r c h a r d g r a s s hay. FORAGE PARTICLE SHORT LONG LENGTH <3.30 3.30- 8.25 8.25-16.50 16.50-33.00 33.00-66.00 >66.00  23.6 29.9 34.0 11.7 0.8 0.0  mm mm mm mm mm mm  a  7.3 mm 1.284  MEDIAN LENGTH: COEFFICIENT OF SPREAD: WEIBULL PARAMETERS:  9.5 9.0 25.5 38.8 15.1 2.1  a  B C  0.136678 1.283979  b  18.1 mm 1.488 b  0.055357 1.487754  Median l e n g t h s and c o e f f i c i e n t s o f spread w i t h d i f f e r e n t s u p e r s c r i p t s were s i g n i f i c a n t l y d i f f e r e n t (P < 0.05).  -126-  TABLE XXII: N u t r i e n t c o n t e n t (%, DM b a s i s ) o f the c o n c e n t r a t e and s h o r t and l o n g chopped o r c h a r d g r a s s hay used i n the experiment. HAY  CONCENTRATE  DM CP NDF ADF a  "  D  86.5 14.9 11.0  a  Means w i t h i n rows w i t h d i f f e r e n t d i f f e r e n t (P < 0.05).  SHORT  LONG  88.1 14.6 68.5 38. 9  86.7 14.0 68.5 38. 3  b  s u p e r s c r i p t s were s i g n i f i c a n t l y  c o m p o s i t i o n between the two chop l e n g t h s o f f o r a g e however, a s i g n i f i c a n t  difference  b  ( T a b l e X X I I ) . There was,  (P < 0.05) i n a c i d  d e t e r g e n t f i b e r (ADF)  c o n t e n t between the f o r a g e and c o n c e n t r a t e , b u t no s i g n i f i c a n t (P > 0.05) i n d r y matter  and crude p r o t e i n c o n t e n t . The two f o r a g e t o  c o n c e n t r a t e r a t i o treatments contents  t h e r e f o r e a l s o had s i g n i f i c a n t l y d i f f e r e n t  covariable  -7  (BW ^) was n o t s i g n i f i c a n t  m e t a b o l i c weight o f the animals  effect,  ADF  (P < 0.05).  Throughout the s t a t i s t i c a l a n a l y s i s o f t h i s experiment  behavior  difference  i n t h i s experiment.  the e f f e c t  (P > 0.05) i n d i c a t i n g  d i d n o t have a s i g n i f i c a n t  There was a l s o no s i g n i f i c a n t  o f the  t h a t the effect  on chewing  (P > 0.05) animal  except on time spent chewing p e r b o l u s r e g u r g i t a t e d d u r i n g  r u m i n a t i o n . Subsequently,  the c o v a r i a b l e and, where a p p r o p r i a t e , the animal  e f f e c t were removed from the G e n e r a l L i n e a r H y p o t h e s i s this t r i a l .  The p a r t i t i o n i n g  f o r the a n a l y s i s o f  o f sums o f squares by the reduced  General  L i n e a r H y p o t h e s i s model f o r each y i e l d v a r i a b l e i s g i v e n i n Appendix A. D e c r e a s i n g the MPL o f the f o r a g e b e i n g f e d d i d n o t s i g n i f i c a n t l y (P > 0.05) the i n t a k e o r chewing time o f the animals  affect  ( T a b l e X X I I I ) . There  was a c o n s i s t e n t t r e n d , however, towards i n c r e a s e d i d l e time and d e c r e a s e d time spent e a t i n g and r u m i n a t i n g when the MPL o f the f o r a g e was  -127-  decreased.  TABLE X X I I I : E f f e c t o f f o r a g e median p a r t i c l e l e n g t h on i n t a k e and chewing c h a r a c t e r i s t i c s . MEDIAN PARTICLE LENGTH (mm) 7.3  18.1  SEM  INTAKE (kg, DM): Hay Cone. Total  10.1 10.2 20.3  10.1 10.3 20.4  0.1 0.1 0.3  CHEWING TIME (min/kg i n t a k e ) : Idling Eating Rumination T o t a l Chewing  33.0 10.9 17.9 28.8  29.2 12.1 19.4 31.4  1.7 0.7 0.8 1.3  RUMINATION CHARACTERISTICS: # B o l i / kg intake Time chewing / Bolus (min)  17.6 1.00  19.7 0.97  1.0 0.01  TABLE XXIV: E f f e c t o f f o r a g e t o c o n c e n t r a t e r a t i o on i n t a k e and chewing c h a r a c t e r i s t i c s . FORAGE:CONCENTRATE 40:60  a  "  b  RATIO  60:40  INTAKE: (kg, DM) Hay Cone. Total  8 .5 12 b 21.2  11.7 7.8 19. 6  CHEWING TIME: (min/kg i n t a k e ) Idling Eating Rumination T o t a l Chewing  32.4 9.7 16. 6 26. 3  29.7 13. 2 20. 7 33. 9  RUMINATION CHARACTERISTICS: # B o l i / kg intake Time chewing / Bolus (min)  16.0 0.99  a  b  a  7  C  a  a  a  a  Mean v a l u e s w i t h i n rows h a v i n g d i f f e r e n t s i g n i f i c a n t l y d i f f e r e n t (P < 0.05).  -128-  a  l  l  d  l  21.3 0.98  SEM 0.1 0.1 0.3  1.7 0.7 0.8 1.3  1.0 0.01  s u p e r s c r i p t s were  Increasing fibre  the p r o p o r t i o n o f f o r a g e  i n the d i e t  significantly e a t i n g and  significantly  increased  ruminating  e a t i n g and  ruminating  per kg o f DM  ingested  intake  (Table XXIV). There  cumulative e f f e c t  and  (P < 0.05)  was  o f time spent  on i n c r e a s i n g the t o t a l time spent chewing per kg  i n c r e a s i n g the p r o p o r t i o n o f hay  idle  voluntary  of  the amount o f time the animals spent  f e e d i n g e s t e d as the p r o p o r t i o n o f f o r a g e  (P > 0.05)  t h e r e f o r e , the p r o p o r t i o n  d e c r e a s e d (P < 0.05)  (P < 0.05)  therefore also a s i g n i f i c a n t  and,  i n the d i e t  i n g e s t e d d i d not  the amount o f time spent i d l e t h e r e was  increased.  significantly  of  Although affect  a t r e n d towards reduced  time. During rumination,  significantly  increased  f e e d i n g e s t e d but  i n c r e a s i n g the p r o p o r t i o n o f f o r a g e (P < 0.05)  i n the  diet  the number o f b o l i r e g u r g i t a t e d per kg  d i d not s i g n i f i c a n t l y  affect  (P > 0.05)  the time spent  TABLE XXV: E f f e c t o f f o r a g e to c o n c e n t r a t e r a t i o and f o r a g e median p a r t i c l e l e n g t h (mm) on i n t a k e and chewing c h a r a c t e r i s t i c s . DIETARY TREATMENTS FORAGE:CONCENTRATE RATIO  40: :60  60: :40  7.,3  18. 1  7. 3  18. 1  SEM  8.,4 12. .6 21..0  8.,5 12. ,8 21.,3  11. ,8 7.,8 19. ,6  11. ,8 7.,8 19. .6  0.,2 0.,2 0.,4  CHEWING TIME (min/kg i n t a k e ) : Idling Eating Rumination T o t a l Chewing  33, .6 9..9 15 .2 25..1  31..3 9..6 18. .0 27..6  32. .4 11..9 20. .6 32. .5  27, .0 14. .5 20. .8 35, .3  2,.4 1..0 1..2 1..8  RUMINATION CHARACTERISTICS: # B o l i / kg i n t a k e Time chewing / Bolus (min)  14, .3 1,.02  17, .7 0,.95  20, .8 0,.98  21, .7 0,.98  1,.5 0,.01  MEDIAN PARTICLE LENGTH INTAKE (kg, Hay Cone. Total  DM):  -129-  of  chewing p e r b o l u s forage being rumination  r e g u r g i t a t e d (Table XXIV). I n c r e a s i n g  the MPL  o f the  f e d a l s o i n c r e a s e d the number o f b o l i r e g u r g i t a t e d  during  b u t the e f f e c t was not s i g n i f i c a n t  Though a l s o n o t s i g n i f i c a n t  (P > 0.05)  (P > 0.05), t h e r e was  reduced time spent chewing p e r b o l u s  (Table  XXIII).  a s t r o n g t r e n d towards a  r e g u r g i t a t e d when the MPL  o f the  forage  increased. There was no s i g n i f i c a n t i n t e r a c t i o n p r o p o r t i o n o f forage  (P > 0.05) between MPL  and the  i n the d i e t on the chewing c h a r a c t e r i s t i c s  animals i n t h i s t r i a l  (Table  o f the  XXV).  DAIRY STEER TRIAL  The p a r t i c l e l e n g t h d i s t r i b u t i o n s forage  o f the f o u r treatments o f chopped  f e d i n t h i s experiment a r e g i v e n i n T a b l e XXVI. There was  s i g n i f i c a n t d i f f e r e n c e (P < 0.05) between the MPL  a  o f the f o u r chop  TABLE XXVI: P a r t i c l e l e n g t h d i s t r i b u t i o n s (% sample wt.) and b u t i o n parameters o f the chopped timothy-brome hay.  lengths  distri-  CHOPPED FORAGE TREATMENTS PARTICLE LENGTH <3.30 3.30- 8.25 8.25-16.50 16.50-33.00 33.00-66.00 >66.00  mm mm mm mm mm mm  MEDIAN LENGTH (mm): COEFFICIENT OF SPREAD: WEIBULL PARAMETERS B: C:  A  B  C  D  36.8 28.4 23.5 8.9 2.5 0.0  23.0 20.3 33.3 17.3 5.5 0.6  20.6 10.2 24.7 33.0 9.9 1.7  13.9 8.0 18.1 35.8 20.8 3.6  a  5.2 0.955 0..192308 0..955450  d  9.0 1.109  13. 3 1.098  20.0 1.219  0.,110988 1..109449  0.075482 1.097834  0.050100 1.218846  b  C  Median l e n g t h s and c o e f f i c i e n t s o f spread w i t h d i f f e r e n t s u p e r s c r i p t s were s i g n i f i c a n t l y d i f f e r e n t (P < 0.05).  -130-  o f f o r a g e b u t no s i g n i f i c a n t  difference  (P > 0.05) between the CS. The  s h o r t e s t l e n g t h o f f o r a g e , however, had the s m a l l e s t CS and the l o n g e s t chop l e n g t h had t h e l a r g e s t .  The CS f o r the middle  chop l e n g t h s were  intermediate. There was a l s o no s i g n i f i c a n t  difference  c o m p o s i t i o n between the f o u r f o r a g e p a r t i c l e  (P > 0.05) i n n u t r i t i o n a l l e n g t h treatments  (Table  XXVII) . The c o n c e n t r a t e t h a t was f e d w i t h the hay had a s i g n i f i c a n t l y h i g h e r crude p r o t e i n  (P < 0.05) and s i g n i f i c a n t l y lower ADF c o n t e n t  (P < 0.05) than  d i d the f o r a g e ; the two f e e d s t u f f s d i d n o t s i g n i f i c a n t l y d i f f e r i n moisture  c o n t e n t . However, s i n c e the f o r a g e t o c o n c e n t r a t e r a t i o  c o n s t a n t throughout  the experiment,  (P > 0.05) i n n u t r i t i o n a l  t h e r e was no s i g n i f i c a n t  The  o f median p a r t i c l e  difference  was o n l y  (Table testing  l e n g t h on chewing b e h a v i o r .  f e e d i n g l e v e l d u r i n g the experiment  was f i x e d a t 9.5 p e r c e n t o f  m e t a b o l i c body weight on an as f e d b a s i s . A l l animals consumed t h e i r  remained  c o m p o s i t i o n between the d i e t a r y treatments  XXVIII) . T h e r e f o r e , as was the o b j e c t i v e , t h i s experiment the e f f e c t  (P > 0.05)  t o t a l f e e d a l l o t m e n t throughout  except the A y r s h i r e  the experiment.  A y r s h i r e ' s i n t a k e , on the b a s i s o f m e t a b o l i c body weight,  The  was lower  than  TABLE XXVII: N u t r i e n t c o n t e n t (%, DM b a s i s ) o f the c o n c e n t r a t e and the f o u r l e n g t h s (mm) o f chopped timothy-brome hay used i n the experiment. CONCENTRATE  FORAGE MEDIAN PARTICLE LENGTH  D.M. CP. NDF ADF  88.3 16.0  b  10. l  a  88.3 12. l 53.7 36. 8  a  b  88.0 11. 6 55.2 39. 2  20.0  13.3  9.0  5.2  a  b  (mm)  87.9 11.4 54.2 37.0 a  b  89.2 11. 5 56.3 38.0  a  b  a-b Means w i t h i n rows w i t h d i f f e r e n t s u p e r s c r i p t s were s i g n i f i c a n t l y d i f f e r e n t (P < 0.05).  -131-  TABLE XXVIII: N u t r i e n t c o n t e n t (%, DM b a s i s ) o f the d i e t a r y treatments (40% c o n c e n t r a t e w i t h 60% timothy-brome hay chopped a t f o u r median p a r t i c l e l e n g t h s ) . FORAGE MEDIAN PARTICLE LENGTH  D.M. CP. ADF  5..2  9..0  13..3  20..0  88..3 13..7 26..1  88..1 13..4 27..6  88..1 13..2 26..2  88..8 13..3 26..8  t h a t f o r the o t h e r s t e e r s and was p e r i o d s o f the experiment.  n o t c o n s t a n t over the f o u r  T h i s may  had any e f f e c t The  (5.2 mm)  the experiment.  I t was  on the i n c i d e n c e o f b l o a t i n t h i s  on time spent i d l e ,  not  f e d to the A y r s h i r e i n the f i r s t  clear period  animal.  c o v a r i a b l e , m e t a b o l i c body weight, had a s i g n i f i c a n t  (P < 0.05)  treatment  have been caused by a c h r o n i c f r o t h y  b l o a t s u f f e r e d by the A y r s h i r e throughout whether the l e n g t h o f hay  (mm)  effect  time spent r u m i n a t i n g and t o t a l time  spent  chewing p e r kg o f i n t a k e , and on the time spent chewing p e r b o l u s r e g u r g i t a t e d d u r i n g r u m i n a t i o n . M e t a b o l i c body weight, however, d i d not have a significant  effect  (P > 0.05)  on the time spent e a t i n g , nor on on the  number o f b o l i r e g u r g i t a t e d d u r i n g r u m i n a t i o n per kg o f f e e d consumed. Where a p p r o p r i a t e , the f o l l o w i n g r e s u l t s m e t a b o l i c body weight squares by the f u l l is  were t h e r e f o r e a d j u s t e d f o r the e f f e c t  on chewing b e h a v i o r . The p a r t i t i o n i n g  of  o f the sums o f  G e n e r a l L i n e a r H y p o t h e s i s model f o r each y i e l d v a r i a b l e  g i v e n i n Appendix B. The r e s u l t s  o f the e f f e c t  o f d e c r e a s i n g the MPL  o f the f o r a g e on the  chewing a c t i v i t y o f the s t e e r s i s shown i n T a b l e XXIX. There was  a  c o n s i s t e n t t r e n d towards d e c r e a s e d time spent e a t i n g per kg o f f e e d i n g e s t e d as the MPL  o f the f o r a g e decreased, b u t t h i s e f f e c t was  (P > 0.05). The  same t r e n d was  not  significant  seen i n the time spent r u m i n a t i n g which  -132-  TABLE XXIX: E f f e c t characteristics.  of forage median p a r t i c l e l e n g t h (mm)  on i n t a k e and chewing  FORAGE MEDIAN PARTICLE LENGTH 5.2  9.0  12.4  a  12.8  a b  12.7  CHEWING TIME (min/kg i n t a k e ) : Idling Eating Rumination T o t a l Chewing  94.4 8.4 16.9 25.3  b  86.1  a b  83.5  RUMINATION CHARACTERISTICS: // B o l i / kg i n t a k e Time chewing / Bolus (min)  18.9 0.856  ^  Covarible effect  9  a  a  13.0  a b  b  ab  23.8 . 0.859  COV  b  0.1  NS  a  2.5 0.5 0.8 1.0  NS * *  1.3 0.018  NS *  77.3 10.3 24.6° 34.9  a  6  * h 20.9° 30.5  SEM  20.0  13.3  INTAKE (kg, DM):  a  (mm)  22.6 32.3  b c  C  b c  b c  28.2 0.794  v ab  31.1° 0.786  of BW^*^^: NS = not s i g n i f i c a n t , * = s i g n i f i c a n t  a-c Mean values w i t h i n rows having (P < 0.05).  different  3  *  (P < 0.05).  s u p e r s c r i p t s were s i g n i f i c a n t l y  different  s i g n i f i c a n t l y decreased cumulative  effect  (P < 0 . 0 5 ) as the MPL o f the f o r a g e decreased. The  o f d e c r e a s i n g the MPL o f t h e f o r a g e on time spent e a t i n g  and r u m i n a t i n g r e s u l t e d i n a s i g n i f i c a n t  (P < 0 . 0 5 ) i n t o t a l  decrease  spent chewing p e r k g o f f e e d i n g e s t e d as t h e MPL o f t h e f o r a g e Subsequently, amount o f time  t h e r e was a concomitant  time  decreased.  i n c r e a s e (P < 0 . 0 5 ) i n the  significant  t h e animals were i d l e p e r k g o f f e e d i n g e s t e d .  During rumination,  t h e r e was a s i g n i f i c a n t  decrease  (P < 0 . 0 5 ) i n the  number o f b o l i r e g u r g i t a t e d p e r k g o f f e e d i n g e s t e d (DM b a s i s ) as the MPL o f the f o r a g e decreased. significantly affected reduced 20.0 The  The time  spent chewing p e r b o l u s r e g u r g i t a t e d was a l s o  (P < 0 . 0 5 ) by the MPL o f the f o r a g e . There was a  amount o f time spent chewing p e r b o l u s when t h e animals were f e d the  mm l e n g t h o f f o r a g e as compared w i t h the 5 . 2 and the 9 . 0 mm l e n g t h s . time spent chewing p e r b o l u s on the 1 3 . 3 mm f o r a g e was i n t e r m e d i a t e b u t  not s i g n i f i c a n t l y d i f f e r e n t  (P > 0 . 0 5 ) from the o t h e r l e n g t h s o f f o r a g e .  C u r v i l i n e a r r e g r e s s i o n was performed on t h e responses  o f the y i e l d  v a r i a b l e s d i s c u s s e d above t o the changes i n f o r a g e MPL. I n g e n e r a l ,  0  75  TABLE XXX: R e g r e s s i o n (Y = a + blogX) and BW covariable c o e f f i c i e n t s f o r t h e e f f e c t o f f o r a g e median p a r t i c l e l e n g t h on chewing and r u m i n a t i o n c h a r a c t e r i s t i c s . BWr 0 . 7 5  REGRESSION  CHEWING TIME (min/kg i n t a k e ) : Idling Eating Ruminating T o t a l chewing RUMINATION CHARACTERISTICS: #Boli / kg intake min chewing / b o l u s * C o v a r i a b l e was s i g n i f i c a n t  a  b  114.233  -28.238  0.98  1.388*  6.380  3.074  0.93  0.226  7.924  12.998  0.99  0.439*  14.259  16.108  0.98  0.667*  3.720  21.285  0.99  0.289 0.009*  (P <  -134-  0.05).  r e g r e s s i n g chewing a c t i v i t y on the l o g a r i t h m o f the MPL o f the f o r a g e gave a b e t t e r f i t t o the d a t a than d i d simple l i n e a r r e g r e s s i o n . The  observed  v a l u e s a r e shown w i t h the p r e d i c t e d r e g r e s s i o n l i n e s i n F i g u r e s 18 and 19 and the r e g r e s s i o n c o e f f i c i e n t s  and the c o e f f i c i e n t s  of determination f o r  each r e g r e s s i o n l i n e a r e g i v e n i n T a b l e XXX, a l o n g w i t h the c o v a r i a b l e coefficients Animals  f o r the e f f e c t o f m e t a b o l i c body weight on chewing a c t i v i t y .  w i t h h i g h e r m e t a b o l i c body weights  more time i d l e and l e s s  time e a t i n g and r u m i n a t i n g p e r kg o f f e e d i n g e s t e d  than d i d l i g h t e r a n i m a l s . L a r g e r animals less  time  tended  spent s i g n i f i c a n t l y (P < 0.05)  a l s o ruminated  for significantly  (P < 0.05) on each b o l u s r e g u r g i t a t e d d u r i n g r u m i n a t i o n . They a l s o  t o r e g u r g i t a t e a s m a l l e r number o f b o l i p e r kg o f f e e d i n g e s t e d b u t  t h i s e f f e c t was n o t s t a t i s t i c a l l y s i g n i f i c a n t  -135-  (P > 0.05).  100  \  90  CD  Idle  CO 8 0 -  Total  Chewing  Rumination •  ... D  Eating  5  10  15  20  M e d i a n Particle Length (mm)  F I G U R E 18: P l o t o f o b s e r v e d v a l u e s a n d p r e d i c t e d r e g r e s s i o n l i n e s (Y = a + b l o g X ) f o r t h e r e l a t i o n s h i p b e t w e e n t h e t i m e s a n i m a l s spent i d l e a n d c h e w i n g p e r k g i n t a k e (Y) a n d t h e m e d i a n p a r t i c l e l e n g t h o f a t i m o t h y - b r o m e g r a s s h a y c h o p p e d t o 4 m e d i a n p a r t i c l e l e n g t h s (X) when t h e h a y was f e d i n a 60% f o r a g e , 4 0 % c o n c e n t r a t e ration.  -136-  CO  •4-*  c  xra 2„«, 0  o  o m +  10 0.90  9  0.80  CO  o m CO  |  CD SZ  O - 0.70 u 0  5  10  15  20  M e d i a n P a r t i c l e L e n g t h (mm)  FIGURE 19: P l o t o f observed v a l u e s and p r e d i c t e d r e g r e s s i o n l i n e (Y = a + b l o g X ) f o r the r e l a t i o n s h i p between the number o f b o l i r e g u r g i t a t e d d u r i n g r u m i n a t i o n per kg o f i n t a k e (Y) and median f o r a g e p a r t i c l e l e n g t h (X), and the e f f e c t o f median p a r t i c l e l e n g t h on time spent chewing per b o l u s r e g u r g i t a t e d when timothy-bromegrass hay was chopped to 4 median p a r t i c l e l e n g t h s and f e d i n a 60% f o r a g e , 40% c o n c e n t r a t e r a t i o n .  -137-  c  DISCUSSION  As  demonstrated by o t h e r r e s e a r c h ,  r e d u c t i o n of p a r t i c l e s i z e i n forages a f f e c t the chewing b e h a v i o r reducing  the MPL  and  i n the p r e s e n t  study,  f e d to ruminants does not  of c a t t l e .  In b o t h o f the p r e s e n t  o f the f o r a g e d i d not s i g n i f i c a n t l y change (P > 0.05)  t r e n d towards a reduced amount o f time spent o f the f o r a g e decreased. One  e a t i n g per kg o f f e e d  ingested the  i n the amount o f comminution  the animals to swallow the r a t i o n s was  s i g n i f i c a n t l y i n h i b i t the r a t e o f i n t a k e . On p r o p o r t i o n o f the f o r a g e  the  a consistent  must t h e r e f o r e conclude t h a t  d i f f e r e n c e between the l e n g t h s o f f o r a g e r e q u i r e d by  always  studies  r a t e o f i n t a k e o f the d i e t s t h a t were f e d . However, t h e r e was  as the MPL  the  minimal and  d i d not  the o t h e r hand, i n c r e a s i n g the  i n the r a t i o n f e d to the d a i r y cows s i g n i f i c a n t l y  i n c r e a s e d the amount o f time r e q u i r e d f o r chewing each kg o f f e e d p r i o r swallowing. The  greater rate of intake f o r concentrates  t h a t f o r f o r a g e s has been r e p o r t e d b e f o r e intake f o r concentrates  may  be  due  as compared w i t h  ( B a l c h , 1958). The  f a s t e r rate of  to a s m a l l e r p a r t i c l e s i z e and/or l e s s  r e s i s t a n c e to comminution by chewing. T h e r e f o r e ,  as the p r o p o r t i o n o f  i n a r a t i o n i n c r e a s e s , one would expect a l o n g e r  time chewing per kg  i n t a k e to be  ruminants can  shown t h a t d e c r e a s i n g  the p a r t i c l e s i z e o f f o r a g e s  i n c r e a s e v o l u n t a r y f e e d i n t a k e and  The  cause o f these  caused by a d e c r e a s e d  decrease the time  e f f e c t s i s b e l i e v e d to be  passage o f p a r t i c l e s from the rumen; the  rumination  forage of  r e q u i r e d p r i o r to swallowing.  R e s e a r c h has  ruminating.  to  spent  a g r e a t e r r a t e of  i n c r e a s e d r a t e o f passage b e i n g  requirement f o r p a r t i c l e s to be reduced i n s i z e  to enable passage through the r e t i c u l o - o m a s a l o r i f i c e .  d e c r e a s e i n time spent  f e d to  ruminating  was  o b s e r v e d i n the d a i r y s t e e r  -138-  by  Such a trial.  Decreasing  the MPL  mm,  to 5.2  or 9.0  spent r u m i n a t i n g  o f the mm  timothy-brome hay  from 20.0  to 9.0  per kg o f i n t a k e . One  hay  i n t a k e s would be  would be  from 18.1  mm  d i d not  ruminating  by  mm  i n MPL  not  the MPL  o f the  orchardgrass  i n t a k e o f the r a t i o n  per kg o f i n t a k e . Why,  therefore, did  s i g n i f i c a n t l y a f f e c t the time spent  the d a i r y cows when s m a l l e r changes had  a significant  when the d a i r y s t e e r s were f e d chopped timothy-brome hay? I n the trial,  the e f f e c t o f r e d u c i n g  d e c r e a s e d . There was  ruminating t h a t was  and  f e d (R  i n c r e a s e d as the MPL  the  of  the  a d i r e c t r e l a t i o s h i p between the time spent  the l o g a r i t h m 2  effect  steer  f o r a g e p a r t i c l e l e n g t h on d e c r e a s i n g  amount o f time the animals spent r u m i n a t i n g forage  rate  t h a t the p o t e n t i a l  s i g n i f i c a n t l y a l t e r the  time the cows spent r u m i n a t i n g  a change o f 10.8  the  increased.  t r i a l , however, d e c r e a s i n g  or the  5.2  animals  associated with a greater  In the d a i r y cow to 7.3  to  would t h e r e f o r e c o n c l u d e t h a t  o f passage o f unruminated p a r t i c l e s from the rumen and higher  13.3  s i g n i f i c a n t l y d e c r e a s e d the amount o f time the  d e c r e a s e s i n time spent r u m i n a t i n g  for  mm,  o f the median p a r t i c l e l e n g t h o f the  = 0.99). T h i s r e l a t i o n s h i p was  forage  s i m i l a r to t h a t d e s c r i b e d  by  Poppi e t a l . (1980) f o r the e f f e c t o f p a r t i c l e s i z e on r e s i s t a n c e to passage from the rumen. On  the b a s i s o f t h e i r f i n d i n g s , Poppi e t a l . (1980)  s u g g e s t e d t h a t t h e r e e x i s t e d a c r i t i c a l p a r t i c l e s i z e above which passage may  be p o s s i b l e , but  Therefore,  the p r o b a b i l i t y o f such passage was  r e l a t e d to the r e s i s t a n c e o f p a r t i c l e  very  low.  s i z e passage from  the  rumen, t h e r e appears to be  a " t h r e s h o l d l e n g t h " below which the r e d u c t i o n  f o r a g e p a r t i c l e l e n g t h may  have a s i g n i f i c a n t e f f e c t on d e c r e a s i n g  spent r u m i n a t i n g  and,  therefore, increasing voluntary  p o s s i b l e t h a t the median p a r t i c l e l e n g t h s d a i r y cow  t r i a l were above the  time  feed intake. I t i s  o f the o r c h a r d g r a s s  " t h r e s h o l d " r e q u i r e d to e l i c i t  -139-  the  of  hay a  f e d i n the  significant  response  i n the time spent r u m i n a t i n g by these  animals.  I t has been r e p o r t e d t h a t the e f f e c t o f d e c r e a s i n g f o r a g e  particle  l e n g t h on i n c r e a s i n g i n t a k e and d e c r e a s i n g the time spent r u m i n a t i n g becomes more pronounced as the f i b e r c o n t e n t o f the f o r a g e i n c r e a s e s (Welch and Smith,  1969a). A l t h o u g h  trials,  d i f f e r e n t f o r a g e s were f e d i n the p r e s e n t two  the ADF c o n t e n t o f the two f o r a g e s was s i m i l a r  o r c h a r d g r a s s hay i n the d a i r y cow t r i a l hay  i n the s t e e r t r i a l ) .  lower CP c o n t e n t  (38.6% ADF f o r the  and 37.8% ADF f o r the timothy-brome  The timothy-brome hay, on the o t h e r hand, had a  (11.7 v s 14.3%) and produced  a much c o a r s e r and s t i f f e r  p a r t i c l e when p r o c e s s e d than d i d the o r c h a r d g r a s s hay. Pearce suggested  t h a t i n c r e a s e d p r o t e i n i n t a k e c o u l d decrease  the c o a r s e n e s s  (1965)  r u m i n a t i o n time, and  o f the timothy-brome hay may i n d i c a t e a g r e a t e r r e s i s t a n c e t o  comminution. T h e r e f o r e , the r e d u c t i o n i n p a r t i c l e l e n g t h o f the lower p r o t e i n c o n t e n t and s t i f f e r timothy-brome hay p a r t i c l e s may have e l i c i t e d a g r e a t e r response  i n chewing b e h a v i o r than t h a t which was e l i c i t e d by the  o r c h a r d g r a s s hay. The  e x p e r i m e n t a l d e s i g n o f the d a i r y cow t r i a l may a l s o have i n f l u e n c e d  the d e t e c t i o n o f s i g n i f i c a n t d i f f e r e n c e s between the e f f e c t s o f the d i e t a r y treatments  on chewing b e h a v i o r . There i s extreme v a r i a t i o n i n the chewing  b e h a v i o r o f ruminants  which, i f u n c o n t r o l l e d , c a n i n t r o d u c e  e x p e r i m e n t a l e r r o r i n t o the r e s u l t s o f experiments.  significant  The d e s i g n used f o r the  s t e e r t r i a l was a b a l a n c e d L a t i n Square whereas t h a t used was a two p e r i o d changeover d e s i g n w i t h f o u r treatments.  f o r the cow t r i a l I n the s t e e r t r i a l  each animal r e c e i v e d each treatment w h i l e i n the d a i r y cow t r i a l  each cow  o n l y r e c e i v e d two o f the f o u r treatments. The unbalanced  n a t u r e o f the cow  trial  t o animal  to  t h e r e f o r e may n o t have f u l l y c o n t r o l l e d the animal  variation  the p o i n t t h a t the d i f f e r e n c e s i n chewing b e h a v i o r between p a r t i c l e  -140-  l e n g t h treatments were not s t a t i s t i c a l l y There was, ruminating  however, a s i g n i f i c a n t  significant.  i n c r e a s e i n the amount o f time  per kg o f i n t a k e as the p r o p o r t i o n o f f o r a g e  the d a i r y cows was  i n c r e a s e d . The  spent  i n the r a t i o n  f e d to  i n c r e a s e i n the p r o p o r t i o n o f f o r a g e  a l s o a s s o c i a t e d w i t h an i n c r e a s e i n the f i b e r c o n t e n t  o f the r a t i o n  has been shown to i n c r e a s e the time spent  Bae  ruminating.  was  which  e t a l . (1981)  demonstrated t h a t , r e g a r d l e s s o f l e v e l o f i n t a k e , i n g e s t e d roughage r e q u i r e d a constant  amount o f comminution per kg o f c e l l w a l l c o n t e n t  from the rumen. T h e r e f o r e , amount o f time r u m i n a t i n g the d i e t  i n c r e a s e s . The  concentrate d a i r y cow  per kg o f i n t a k e as the p r o p o r t i o n o f f o r a g e  detection of a s i g n i f i c a n t  trial  supports  on the p r o c e s s  of forage  to  time i n the  t h a t the c o m p o s i t i o n  o f the d i e t  has  o f d i g e s t i o n i n the ruminant (Mertens  and  1982).  i n c r e a s i n g the MPL  to c o n c e n t r a t e  i n the s t e e r t r i a l  of b o l i r e g u r g i t a t e d during rumination. the hay  f e d to the s t e e r s was  change i n the time spent  rumination  when the p r o p o r t i o n o f f o r a g e  f o r a g e was  altered.  rumination  o f the l o n g e s t hay  The  Shirlaw  duration of rumination  i n the d a i r y cow  Except when the p a r t i c l e mm,  t h e r e was  of mastication  i n the d i e t or the MPL  i n c r e a s e i n the e f f i c i e n c y  length of  no  r e g u r g i t a t e d i n each  change i n the e f f i c i e n c y  significant trial. during of  of m a s t i c a t i o n  f e d to the s t e e r s i s d i f f i c u l t  (1955) found t h a t chopping o f l o n g hay  the during  to e x p l a i n . increased  c y c l e s as compared w i t h t h a t when the l o n g hay  I t i s p o s s i b l e t h a t the l o n g e r l e n g t h o f p a r t i c l e s  -141-  trial  s i g n i f i c a n t l y i n c r e a s e d the number  chewing per b o l u s  t h e r e was  Duckworth and  no  ratio  i n c r e a s e d to 20.0  Therefore,  fed.  effect  in  l e n g t h , on r u m i n a t i o n  the s u g g e s t i o n  Both i n c r e a s i n g the f o r a g e and  would expect animals to spend a g r e a t e r  r a t i o , but not o f p a r t i c l e  the g r e a t e s t e f f e c t Ely,  one  f o r passage  the was  i n the rumen cause  the f o r m a t i o n o f a l i g h t e r b o l u s d u r i n g r u m i n a t i o n . Such a b o l u s would r e q u i r e l e s s comminution than a b o l u s o f the same volume made up o f a g r e a t e r weight o f s h o r t e r p a r t i c l e s . U n f o r t u n a t e l y no r e s e a r c h has been done to  i n v e s t i g a t e the e f f e c t o f d i e t p a r t i c l e s i z e on the p a r t i c l e s i z e  and  weight o f b o l i r e g u r g i t a t e d d u r i n g r u m i n a t i o n . The et  chewing r e s u l t s i n the d a i r y s t e e r t r i a l  a l . (1983) who  showed t h a t l a r g e r animals were more e f f i c i e n t  than were s m a l l e r a n i m a l s . was  support the r e s u l t s o f  In the s t e e r t r i a l ,  a s s o c i a t e d w i t h a s i g n i f i c a n t decrease  Bae  chewers  h i g h e r m e t a b o l i c body weight  i n time spent e a t i n g and  r u m i n a t i n g p e r kg o f f e e d i n g e s t e d , and a decrease  i n the time spent  per bolus r e g u r g i t a t e d during rumination. Although  the t r e n d s were s i m i l a r  to  those found i n the s t e e r t r i a l ,  m e t a b o l i c body weight d i d not have a  s i g n i f i c a n t e f f e c t on the chewing b e h a v i o r of  for  i n the d a i r y cow  d e t e c t i o n o f a s i g n i f i c a n t e f f e c t o f body weight may  experimental  d e s i g n t h a t was  used and  trial.  The  have been due  i t s i n a b i l i t y to c o m p l e t e l y  a l l the e f f e c t s o f animal v a r i a t i o n i n the The  lack to the  account  experiment.  e f f e c t s o f h i g h e r m e t a b o l i c body weight on chewing b e h a v i o r  l i k e l y due  chewing  are  t o an i n c r e a s e d s i z e o f the mouth, t e e t h s u r f a c e a r e a , esophagus  and r e t i c u l o - o m a s a l o r i f i c e  i n l a r g e r animals. Greater prehension  potential,  more g r i n d i n g s u r f a c e on the t e e t h , and a l a r g e r esophagus would a l l o w a g r e a t e r r a t e o f i n t a k e w i t h a reduced  time requirement  to  to a l a r g e r esophagus, l a r g e r  swallowing.  D u r i n g r u m i n a t i o n , due  f o r comminution p r i o r animals  c o u l d r e g u r g i t a t e l a r g e r b o l i which c o u l d be more e f f i c i e n t l y reduced s i z e by the l a r g e r s u r f a c e a r e a o f the t e e t h . F i n a l l y ,  a larger  r e t i c u l o - o m a s a l o r i f i c e c o u l d pass l a r g e r p a r t i c l e s than those passed s m a l l e r a n i m a l . T h i s would i n c r e a s e the r a t e o f passage o f d i g e s t a and decrease  the requirement  f o r time spent r u m i n a t i n g per kg o f i n t a k e i n  -142-  in  in a  l a r g e r a n i m a l s . Bae e t a l (1983), however, found t h a t f e c a l p a r t i c l e d i d not s i g n i f i c a n t l y d i f f e r f o r d i f f e r e n t  -143-  body s i z e s  i n their  size  experiments.  SUMMARY  The p r e s e n t study i n v e s t i g a t e d the e f f e c t  o f f o r a g e median  particle  l e n g t h and f o r a g e t o c o n c e n t r a t e r a t i o on the chewing b e h a v i o r  i n dairy  cattle.  I n the f i r s t  o r c h a r d g r a s s hay  experiment,  lactating  chopped t o two MPLs (7.3 and 18.1  concentrate r a t i o s  (40:60 and 60:40) ad l i b i t u m .  d a i r y s t e e r s were f e d timothy-brome hay and 20.0 body  mm)  d a i r y c a t t l e were f e d mm)  i n two  f o r a g e to  I n the second  experiment,  chopped to f o u r MPLs (5.2,  i n a 60:40 f o r a g e c o n c e n t r a t e r a t i o a t 9.5  9.0,  13.3  percent of metabolic  weight. In  the d a i r y cow  not s i g n i f i c a n t l y  trial,  affect  d e c r e a s i n g the p a r t i c l e  l e n g t h o f the f o r a g e d i d  the chewing b e h a v i o r o f the c a t t l e .  p r o p o r t i o n o f f o r a g e i n the d i e t , however, s i g n i f i c a n t l y  I n c r e a s i n g the  increased voluntary  f e e d i n t a k e , i n c r e a s e d the time spent r u m i n a t i n g and t o t a l time chewing per kg o f i n t a k e , and  i n c r e a s e d the number o f b o l i r e g u r g i t a t e d p e r kg o f i n t a k e  d u r i n g r u m i n a t i o n . E a t i n g time was p r o p o r t i o n o f f o r a g e i n the r a t i o n . interaction ration  between the e f f e c t s  not s i g n i f i c a n t l y There was  o f MPL  on the chewing b e h a v i o r o f the  D e c r e a s i n g the MPL significantly  decreased  a l s o no  a f f e c t e d by  the  significant  and the p r o p o r t i o n o f f o r a g e i n the cattle.  o f the timothy-brome hay the time the animals  f e d t o the s t e e r s  spent r u m i n a t i n g and t o t a l  time  chewing p e r kg o f i n t a k e and i n c r e a s e d the number o f b o l i r e g u r g i t a t e d d u r i n g r u m i n a t i o n . There was  a l s o evidence  t h a t the e f f i c i e n c y  of  m a s t i c a t i o n d u r i n g r u m i n a t i o n i n c r e a s e d as the MPL  o f the f o r a g e i n c r e a s e d .  The MPL  the time spent e a t i n g per  o f the f o r a g e d i d not s i g n i f i c a n t l y  kg o f i n t a k e . There was  a direct  relationship  affect  between the l o g a r i t h m o f  and the chewing b e h a v i o r o f the s t e e r s . T h i s r e l a t i o n s h i p  -144-  suggested  MPL  that  t h e r e e x i s t e d a " t h r e s h o l d l e n g t h " below which the e f f e c t behavior the  becomes s i g n i f i c a n t .  D i f f e r e n c e s i n the m e t a b o l i c  s t e e r s d u r i n g the experiment a l s o had a s i g n i f i c a n t  behavior.  -145-  o f MPL  on chewing  body weight o f  effect  on chewing  GENERAL SUMMARY AND CONCLUSIONS The p a r t i c l e s i z e o f f o r a g e s i n ruminant d i e t s a f f e c t s the r a t e o f passage o f u n d i g e s t e d  f e e d p a r t i c l e s from the rumen, the r u m i n a l  d i g e s t i b i l i t y o f the r a t i o n , and, t h e r e f o r e , the chewing b e h a v i o r o f the a n i m a l . However, u n t i l r e c e n t l y , o n l y q u a l i t a t i v e o r s e m i - q u a n t i t a t i v e methods have been used to c h a r a c t e r i z e the p a r t i c l e processed  size distribution i n  f o r a g e . A method f o r the q u a n t i t a t i o n o f the p a r t i c l e  d i s t r i b u t i o n i n processed  f o r a g e was t h e r e f o r e developed,  length  t e s t e d , and used  to i n v e s t i g a t e the e f f e c t o f p r o c e s s i n g method and f o r a g e type on the p a r t i c l e length d i s t r i b u t i o n i n processed  f o r a g e . The same method was a l s o  u s e d to i n v e s t i g a t e the 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 on v o l u n t a r y f e e d i n t a k e and chewing b e h a v i o r  i n dairy cattle.  A simple v i b r a t i n g t r a y f o r a g e p a r t i c l e s e p a r a t o r to s e p a r a t e  forage p a r t i c l e s  (FPS) was c o n s t r u c t e d  into s i x t h e o r e t i c a l length fractions  4-10, 10-20, 20-40, 40-80 and >80 mm).  The method o f a p p l i c a t i o n o f forage  p a r t i c l e s t o the FPS d u r i n g s e p a r a t i o n s i g n i f i c a n t l y a f f e c t e d measurement o f the p a r t i c l e  (<4,  (P < 0.05) the  l e n g t h d i s t r i b u t i o n . The s e p a r a t i o n r e s u l t s ,  however, were r e p e a t a b l e w i t h i n a g i v e n method o f a p p l i c a t i o n . When o r c h a r d g r a s s hay, chopped a t t h r e e t h e o r e t i c a l l e n g t h s o f c u t (TLC: 3.18, 6.35 and 9.53 mm),  was s e p a r a t e d ,  o n l y 56.6% o f a l l p a r t i c l e s  s e p a r a t e d (by  weight) were c o r r e c t l y c l a s s i f i e d i n t o the above t h e o r e t i c a l p a r t i c l e frations;  32.4% were o v e r s i z e d ( c l a s s i f i e d as b e i n g l o n g e r than  a c t u a l l y were) and 11.0% were u n d e r s i z e d  length  they  ( c l a s s i f i e d as b e i n g s h o r t e r than  they a c t u a l l y were). Based on t h i s degree o f over and u n d e r s i z i n g , the theoretical particle to be <3.3,  l e n g t h f r a c t i o n s c l a s s i f i e d by the FPS were c a l i b r a t e d  3.3-8.25, 8.25-16.5, 16.5-33.0, 33.0-66.0 and >66.0 mm. Because  -146-  the FPS s e p a r a t e d p a r t i c l e s on the b a s i s o f a s p e c i f i c s i z e parameter, the measurement o f f o r a g e p a r t i c l e s i z e by t h i s method i s more a p p r o p r i a t e i s the measurement o f an u n i d e n t i f i e d p a r t i c l e s i z e parameter u s i n g S e p a r a t i o n d a t a f o r the chopped o r c h a r d g r a s s hay, e x p r e s s e d cumulative  f u n c t i o n . Only  a lognormal  distribution,  the W e i b u l l f u n c t i o n a d e q u a t e l y  sieving.  as p e r c e n t  weight u n d e r s i z e , was f i t t e d by r e g r e s s i o n to a l i n e a r  two e x p o n e n t i a l e q u a t i o n s ,  than  equation,  and a m o d i f i e d W e i b u l l  f i t the s e p a r a t i o n d a t a . The  c o e f f i c i e n t s o f d e t e r m i n a t i o n f o r the W e i b u l l f u n c t i o n were a l l g r e a t e r  than  0.99 and the r e s i d u a l s were randomly d i s t r i b u t e d around the p r e d i c t e d r e g r e s s i o n l i n e . The median p a r t i c l e l e n g t h (MPL) c o u l d be p r e d i c t e d by the i n v e r s e o f the B parameter i n the m o d i f i e d W e i b u l l f u n c t i o n w h i l e the use o f the C parameter (named the c o e f f i c i e n t o f spread  [CS]) as a measure o f the  s p r e a d o f p a r t i c l e l e n g t h s around a g i v e n median was d i s c u s s e d . A l f a l f a and low and h i g h q u a l i t y o r c h a r d g r a s s hays were hammermilled through  a 12.7 mm  s c r e e n and chopped a t 3 TLC (3.18, 6.35 and 9.53 mm)  and  s e p a r a t e d on the FPS to determine the d r y matter (DM), crude p r o t e i n (CP) and a c i d d e t e r g e n t  fiber  (ADF) MPL and CS o f each p r o c e s s e d  forage.  were b a s e d on the weight o f each n u t r i e n t c o l l e c t e d i n each p a r t i c l e f r a c t i o n on the FPS. There was a s i g n i f i c a n t i n t e r a c t i o n  length  (P < 0.05) between  the e f f e c t o f p r o c e s s i n g method and f o r a g e type on the DM, and CS produced i n the p r o c e s s e d  The MPL  CP and ADF  MPL  f o r a g e . Furthermore, the d i f f e r e n c e s i n DM  MPL and CS between f o r a g e s were s i g n i f i c a n t l y d i f f e r e n t  (P < 0.05) from  those f o r CP and ADF. There were a l s o s i g n i f i c a n t d i f f e r e n c e s (P < 0.05) between the DM and CP MPL, Therefore, d i f f e r e n t  and the DM and ADF MPL, w i t h i n each f o r a g e  type.  f o r a g e s p r o c e s s e d by the same method do n o t always  r e s u l t i n the p r o d u c t i o n o f s i m i l a r DM,  CP and ADF MPL o r CS w i t h i n o r  between f o r a g e t y p e s . Lack o f q u a n t i f i c a t i o n o f p a r t i c l e s i z e i n r e s e a r c h  -147-  using processed dietary  f o r a g e may  different  MPL  H o l s t e i n cows were f e d o r c h a r d g r a s s hay  (7.3 and 18.1  and 60:40) i n a two by two d e s i g n . The (P > 0.05)  particle  mm)  a t two  chopped to  f o r a g e to c o n c e n t r a t e r a t i o s  f a c t o r i a l arrangement i n a two  v o l u n t a r y f e e d i n t a k e (VFI) or chewing b e h a v i o r . i n the d i e t  significantly  two  (40:60  p e r i o d changeover  l e n g t h o f the f o r a g e d i d not s i g n i f i c a n t l y  f o r a g e to c o n c e n t r a t e r a t i o  affect  I n c r e a s i n g the  (P < 0.05)  decreased  i n c r e a s e d the time spent chewing per kg o f f e e d i n t a k e d u r i n g e a t i n g  and r u m i n a t i o n and  i n c r e a s e d the number o f b o l i r e g u r g i t a t e d p e r kg o f f e e d  i n t a k e d u r i n g r u m i n a t i o n . Time spent  i d l e p e r kg o f f e e d i n t a k e and  chewing per b o l u s r e g u r g i t a t e d d u r i n g r u m i n a t i o n were not affected  (P > 0.05)  significant  by the f o r a g e to c o n c e n t r a t e r a t i o o f the d i e t . interaction  (P > 0.05)  no  between the e f f e c t s  and  f o r a g e to c o n c e n t r a t e r a t i o on VFI and chewing b e h a v i o r . When d a i r y s t e e r s were f e d timothy-brome hay and  20.0  Square d e s i g n , (P < 0.05)  mm)  i n c r e a s i n g the MPL  decreased  idle,  (5.2,  in a 4 x 4  o f the f o r a g e i n the d i e t  the time spent  time  i n c r e a s e d the time  There  of forage  chopped to 4 MPL  a t a 60:40 f o r a g e to c o n c e n t r a t e r a t i o  the  significantly  was  13.3  into  treatments.  Twelve l a c t a t i n g  VFI,  therefore introduce uncontrolled v a r i a t i o n  MPL  9.0,  Latin  significantly spent  r u m i n a t i n g and the t o t a l time spent chewing ( e a t i n g p l u s r u m i n a t i o n ) ,  and  i n c r e a s e d the number o f b o l i r e g u r g i t a t e d p e r kg o f f e e d i n t a k e . These effects to 5.2  o f f o r a g e MPL  on chewing b e h a v i o r were shown to be d i r e c t l y  the l o g a r i t h m o f the f o r a g e MPL. o r 9.0  mm  to 20.0  mm  I n c r e a s i n g the MPL  a l s o s i g n i f i c a n t l y decreased  o f the f o r a g e (P < 0.05)  spent chewing p e r b o l u s r e g u r g i t a t e d d u r i n g r u m i n a t i o n . The MPL f o r a g e , however, d i d not have a s i g n i f i c a n t p e r kg o f f e e d i n t a k e d u r i n g e a t i n g .  -148-  effect  the  related from time  o f the  on the time spent  chewing  Body s i z e , significant not  i n c l u d e d as a c o v a r i a b l e  effect  (P < 0.05)  i n the d a i r y cow  increased e a t i n g and  and  trial.  rumination,  As body s i z e  decreased. L a r g e r  becomes  time spent  during  trials  but  both  rumination.  particle  length,  and body  i n d i c a t e d t h a t t h e r e may  size,  exist the  l e n g t h on the d i g e s t i o n p r o c e s s i n ruminants  significant.  -149-  a  time  l e n g t h , p o s s i b l y r e l a t e d to body s i z e , below which  of d i e t a r y p a r t i c l e  had  idle  animals a l s o spent l e s s  o f forage  on chewing b e h a v i o r between the two  effect  increased,  regurgitated during  d i f f e r e n c e s i n the e f f e c t  maximum p a r t i c l e  trials,  on chewing b e h a v i o r i n the s t e e r t r i a l ,  the time spent chewing per kg o f f e e d i n t a k e ,  chewing each b o l u s t h a t was The  i n both d a i r y c a t t l e  a  LITERATURE  CITED  A l l e n , M.S., J.B. R o b e r t s o n and P.J. Van Soest. 1984. A comparison o f p a r t i c l e s i z e methodologies and s t a t i s t i c a l treatments. I n : Techniques i n P a r t i c l e S i z e A n a l y s i s o f Feed and D i g e s t a i n Ruminants. (P.M. Kennedy, E d . ) . Occ. Pub. 1, Canadian S o c i e t y o f Animal S c i e n c e , Edmonton, A l b e r t a , Canada: 39-56. ASAE. 1969(a). Method o f d e t e r m i n i n g and e x p r e s s i n g f i n e n e s s o f f e e d m a t e r i a l s by s i e v i n g . Standard ASAE S319. A g r i c u l t u r a l E n g i n e e r i n g Yearbook: 346-347. ASAE. 1969(b). Method o f d e t e r m i n i n g modulus o f u n i f o r m i t y and modulus o f f i n e n e s s o f ground f e e d . Recommendation ASAE R246.1. A g r i c u l t u r a l E n g i n e e r i n g Yearbook: 348. ASAE. 1983. Method o f d e t e r m i n i n g and e x p r e s s i n g f i n e n e s s o f f e e d m a t e r i a l s by s i e v i n g . Standard ASAE S319. A g r i c u l t u r a l E n g i n e e r i n g Yearbook: 325-326. American S o c i e t y o f Animal S c i e n c e . 1969. Summary o f the minutes o f the 61st b u s i n e s s meeting o f the American S o c i e t y o f Animal S c i e n c e . J . Anim. S c i . 29: 1021. Bae,  Dong Ho, J.G. Welch and A.M. Smith. 1981. E f f i c i e n c y o f m a s t i c a t i o n i n r e l a t i o n t o hay i n t a k e by c a t t l e . J . Anim. S c i . 52: 1371-1375.  Bae,  Dong ho, J.G. Welch, and B.E. Gilman. 1983. M a s t i c a t i o n and r u m i n a t i o n i n r e l a t i o n t o body s i z e o f c a t t l e . J . D a i r y S c i . 66: 2137-2141.  B a i l y , C B . and C C B a l c h . 1961. The d i g e s t i o n o f hay a d m i n i s t e r e d rumen f i s t u l a s . B r i t . J . Nutr. 12: 183.  through  Balch, C C 1952. 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 o f f o o d by d a i r y cows: 6. The r a t e o f c o n t r a c t i o n o f the r e t i c u l u m . B r i t . J . Nutr. 6: 366-375. Balch, C C 1958. O b s e r v a t i o n s 12: 330-345.  on the a c t o f e a t i n g i n c a t t l e . Br. J . Nutr.  B a l c h , C C . 1971. P r o p o s a l t o use time spent chewing as an index o f the e x t e n t to which d i e t s f o r ruminants possess the p h y s i c a l p r o p e r t y o f f i b r o u s n e s s c h a r a c t e r i s t i c o f roughages. Br. J . Nutr. 26: 383-392. Balch, C C and R.C. Campling. 1962. R e g u l a t i o n o f v o l u n t a r y i n t a k e i n ruminants. Nutr. Abs. and Rev. 32: 669-686 B a l c h , C C , A. K e l l y and G. Heim. 1951. 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 o f f o o d by d a i r y cows: 4. The a c t i o n o f the r e t i c u l o - o m a s a l o r i f i c e . Br. J . Nutr. 5: 207-216.  -150-  Bechet, G.. 1978. E n r e g i s t r e m e n t des a c t i v i t e s a l i m e n t a i r e s e t meryciques des o v i n s au paturage. Ann. Zootech. 27: 107-113. Campling, R . C , M. F r e e r and C C . B a l c h . 1963. F a c t o r s a f f e c t i n g the v o l u n t a r y i n t a k e o f f o o d by cows: 6. A p r e l i m i n a r y experiment w i t h ground, p e l l e t e d hay. Br. J . Nutr. 17: 263-272. Campling, R.C. and M. F r e e r . 1962. The e f f e c t o f s p e c i f i c g r a v i t y and s i z e on the mean time o f r e t e n t i o n o f i n e r t p a r t i c l e s i n the a l i m e n t a r y t r a c t o f the cow. Br. J . Nutr. 16: 507-518. Campling, R.C. and M. F r e e r . 1966. F a c t o r s a f f e c t i n g the v o l u n t a r y i n t a k e o f f o o d by cows: 8. Experiments w i t h ground, p e l l e t e d roughages. Br. J . Nutr. 20: 229-244. C a s t l e , M.E., E l i z a b e t h Macdaid and J.N. Watson. 1975. The automatic r e c o r d i n g o f the g r a z i n g b e h a v i o r o f d a i r y cows. J . Br. G r a s s l d . Soc. 30: 161-163. Chambers, A.R.M., J . Hodgson and J.A. M i l n e . 1981. The development and use o f equipment f o r the automatic r e c o r d i n g o f i n g e s t i v e b e h a v i o r i n sheep and c a t t l e . Grass and F o r . S c i . 36: 97-105. C h o i , S.C. 1978. I n t r o d u c t o r y A p p l i e d S t a t i s t i c s Inc., New J e r s e y .  i n Science. P r e n t i c e - H a l l  Duckworth, J . E . , and D.W. S h i r l a w . 1955. The development o f an apparatus to r e c o r d the jaw movements o f c a t t l e . Br. J . Anim. Behav. 3: 56-60. Duckworth, J . E . , and D.W. S h i r l a w . 1958. A study o f f a c t o r s a f f e c t i n g f e e d i n t a k e and the e a t i n g b e h a v i o r o f c a t t l e . Anim. Behav. 6: 147-154. E h l e , F.R. 1984. I n f l u e n c e o f p a r t i c l e s i z e on d e t e r m i n a t i o n components. J . D a i r y S c i . 67: 1482-1488.  of f i b r o u s feed  E h l e , F.R., M.R. Murphy and J.H. C l a r k . 1982. I n s i t u p a r t i c l e s i z e r e d u c t i o n and the e f f e c t o f p a r t i c l e s i z e on d e g r e d a t i o n o f crude p r o t e i n and d r y matter i n the rumen o f d a i r y s t e e r s . J . D a i r y S c i . 65: 963-971. Elimam, M.E. and E.R. Orskov. 1984. F a c t o r s a f f e c t i n g the o u t f l o w o f p r o t e i n supplements from the rumen: 2. The c o m p o s i t i o n and p a r t i c l e s i z e o f the b a s a l d i e t . Anim. Prod. 39: 201-206. Ensor, W.L., H.H. O l s o n and V.F. Colenbrander. 1970. A r e p o r t : Committee on c l a s s i f i c a t i o n o f p a r t i c l e s i z e i n f e e d s t u f f s . J . D a i r y S c i . 53: 689-690. Evans, E.W., G.R. Pearce, J . B u r n e t t and Susan L. P i l l i n g e r . 1973. Changes i n some p h y s i c a l c h a r a c t e r i s t i c s o f the d i g e s t a i n the r e t i c u l o - r u m e n o f cows f e d once d a i l y . Br. J . Nutr. 29: 357-376.  -151-  F e l l e r , R. and A. Foux. 1975. O s c i l l a t i n g s c r e e n motion e f f e c t on the p a r t i c l e passage through p e r f o r a t i o n s . Trans. Am. Soc. A g r i c . Engrs. 18: 926-931. F i n n e r , M.F., J . E . H a r d z i n s k i and L.L. Pagel J r . . 1978. E v a l u a t i n g p a r t i c l e l e n g t h o f chopped f o r a g e , ASAE T e c h n i c a l Paper No. 78-1047. Fonnesbeck, P.V., J . L . C h r i s t i a n s e n and L.E. H a r r i s . 1981. F a c t o r s a f f e c t i n g d i g e s t i b i l i t y o f n u t r i e n t s by sheep. J . Anim. S c i . 52: 363-376. F r e e r , M. and R.C. Campling. 1965. F a c t o r s a f f e c t i n g the v o l u n t a r y i n t a k e o f f o o d by cows: 7. The b e h a v i o r and r e t i c u l a r m o t i l i t y o f cows g i v e n d i e t s o f hay, d r i e d g r a s s , c o n c e n t r a t e s and ground, p e l l e t e d hay. B r i t . J . N u t r . 19: 195-207. F r e e r , M., R.C. Campling and C.C. B a l c h . 1962. F a c t o r s a f f e c t i n g the v o l u n t a r y i n t a k e o f food by cows: 4. The b e h a v i o r and r e t i c u l a r m o t i l i t y o f cows r e c e i v i n g d i e t s o f hay, o a t straw and o a t straw w i t h u r e a . B r i t J . N u t r . 16: 279-295. Gale, G.E. and M.J. O'Dogherty. 1982. An apparatus f o r the assessment o f the l e n g t h d i s t r i b u t i o n o f chopped f o r a g e . J . A g r i c . Engng. Res. 27: 35-43. G i l l , J . L . , and W.T. Magee. 1976. B a l a n c e d t w o - p e r i o d changeover d e s i g n s f o r s e v e r a l treatments. J . Anim. S c i . 42: 775-777. G i l l , J . , R.C. Campling and D.R. Westgarth. 1966. A study d u r i n g e a t i n g i n the cow. Br. J . Nutr. 20: 13-23.  o f chewing  Gordon, J.G. 1958. The r e l a t i o n s h i p between f i n e n e s s o f g r i n d i n g o f f o o d and r u m i n a t i o n . J . A g r i c . S c i . 51: 78-80. H a l l , G.E., R.D. Brazee and C.W. H a l l . 1970. C r o s s - s e c t i o n a l a r e a measurement o f a l f a l f a stems. Trans. Am. Soc. A g r i c . Engrs. 13: 577-579, 586. Headley, V. and H. P f o s t . 1970. D e s c r i b i n g p a r t i c l e s i z e . Feed M a n u f a c t u r i n g Tech. (H.B. P f o s t , Ed.) AFMA - Feed P r o d u c t i o n C o u n c i l : 563-568. Herdan, G. 1960. Small P a r t i c l e S t a t i s t i c s . New York.  2nd ed.. Academic Press I n c . ,  Hooper, A.P., and J.G. Welch. 1985. Change o f f u n c t i o n a l s p e c i f i c g r a v i t y o f f o r a g e s i n v a r i o u s s o l u t i o n s . J . D a i r y S c i . 68: 1652-1658. J a s t e r , E.H. and M.R. Murphy. 1983. E f f e c t s o f v a r y i n g p a r t i c l e s i z e o f f o r a g e on d i g e s t i o n and chewing b e h a v i o r o f d a i r y h e i f e r s . J . D a i r y S c i . 66: 802-810. J o h n s t o n e - W a l l a c e , D.B.. 1953. Animal b e h a v i o r Roy. A g r i c . Soc. 114: 11-20.  -152-  and g r a z i n g management. J .  Jones, J.R. and G. Moseley. 1977. A wet s i e v i n g t e c h n i q u e f o r e s t i m a t i n g p a r t i c l e s i z e d i s t r i b u t i o n i n sheep d i g e s t a . Lab. P r a c t . 26: 687-689. J o r g e n s e n , N.A., M.F. F i n n e r and J.P. Marquardt. 1978. E f f e c t o f f o r a g e p a r t i c l e s i z e on a n i m a l performance. ASAE Paper No. 1048. P r e s . Summer Mtg. Am. Soc. A g r i c . Eng., Logan, UT. Kennedy, P.M., Ed. 1984. Summary and c o n c l u s i o n s from d i s c u s s i o n . Techniques i n P a r t i c l e S i z e A n a l y s i s o f Feed and D i g e s t a i n Ruminants. Occ. Pub. 1, Canadian S o c i e t y o f Animal S c i e n c e , Edmonton, A l b e r t a , Canada: 184-186. K i c k , C H . and P. G e r l a u g h . 1935. The p r e p a r a t i o n o f feeds f o r c a t t l e . Proc. Amer. Soc. Anim. Prod. 28th Ann. M e e t i n g : 93-98. K i c k , C H . , P. G e r l a u g h and A.F. S c h a l k . 1937. The e f f e c t o f m e c h a n i c a l p r o c e s s i n g o f feeds on the m a s t i c a t i o n and r u m i n a t i o n o f s t e e r s . J . A g r i c . Res. 55: 587-597. K i n g , K.W. and W.E.C. Moore. 1957. D e n s i t y and s i z e as f a c t o r s a f f e c t i n g the passage r a t e o f i n g e s t a i n the b o v i n e and human d i g e s t i v e t r a c t s . J . D a i r y S c i . 40: 528-536. Kolmogoroff, A.N. 1941. Uber das l o g a r i t h m i s c h normale v e r t e i l u n g s g e s e t z der dimensionen der t e i l e h e n b e i z e r s t u c k e l u n g . Comptes Rendus (Doklady) de l'Academie des S c i e n c e s de l'URSS, 31: 99. D e s c r i b e d i n Herdan, G. 1960. S m a l l P a r t i c l e S t a t i s t i c s . 2nd ed.. Academic P r e s s Inc., New York. Kydd, W.L. and G. M u l l i n s . 1963. A t e l e m e t r y system f o r i n t r a o r a l A r c h . O r a l B i o l . 8: 235-236. Law,  pressures.  S.E. and E.M. Sudweeks. 1975. E l e c t r o n i c t r a n s d u c e r f o r r u m i n a t i o n r e s e a r c h . J . Anim. S c i . 41: 213-218.  Lee, J.A. and G.R. Pearce. 1984. The e f f e c t i v e n e s s o f chewing d u r i n g e a t i n g on p a r t i c l e s i z e r e d u c t i o n o f roughages by c a t t l e . A u s t . J . A g r i c . Res. 35: 609-618. L e v e i l l e , M. , J.P. Jouany and J.P. Brun. 1979. A n a l y s e automatique du comportement a l i m e n t a i r e e t merycique chez l e mouton. Ann. B i o l . Anim. B i o c h . B i o p h y s . 19: 889-893. L u g i n b u h l , J.M., K.R. Pond, J.C. Russ and E.A. T o l l e y . 1984. Use o f microcomputer i n f e e d s t u f f p a r t i c l e s i z e e v a l u a t i o n : a d i r e c t approach. I n : Techniques i n P a r t i c l e S i z e A n a l y s i s o f Feed and D i g e s t a i n Ruminants. (P.M. Kennedy, E d . ) . Occ. Pub. 1, Canadian S o c i e t y o f Animal S c i e n c e , Edmonton, A l b e r t a , Canada: 57-61. McLeod, M.N., P.M. Kennedy and D.J. Minson. 1984. Dimensions o f p a r t i c l e s r e t a i n e d on s i e v e s d u r i n g a wet s i e v i n g p r o c e d u r e . Techniques i n P a r t i c l e S i z e A n a l y s i s o f Feed and D i g e s t a i n Ruminants. (P.M. Kennedy, E d . ) . Occ. Pub. 1, Canadian S o c i e t y o f Animal S c i e n c e , Edmonton, A l b e r t a , Canada: 168.  -153-  Mertens, D.R. and L.O. E l y . 1982. R e l a t i o n s h i p o f r a t e and e x t e n t o f d i g e s t i o n to f o r a g e u t i l i z a t i o n - a dynamic model e v a l u a t i o n . J . Anim. S c i . 54: 895-905. M o l l e r , F.. 1975. D e t e r m i n a t i o n o f p a r t i c l e l e n g t h T r a n s . Am. Soc. A g r i c . Engrs. 18: 950-951.  i n cobs and  wafers.  Moseley, G. 1984. The a n a l y s i s and d e s c r i p t i o n o f p a r t i c l e s i z e d i s t r i b u t i o n o f d i g e s t a . In: Techniques i n P a r t i c l e S i z e A n a l y s i s o f Feed and D i g e s t a i n Ruminants. (P.M. Kennedy, Ed.). Occ. Pub. 1, Canadian S o c i e t y o f Animal S c i e n c e , Edmonton, A l b e r t a , Canada: 22-38. Murphy, M.R. and R.E. Bohrer. 1984. Tenable assumptions about comminution l e a d i n g to lognormal or Rosin-Rammler ( W e i b u l l ) p a r t i c l e s i z e d i s t r i b u t i o n s . In: Techniques i n P a r t i c l e S i z e A n a l y s i s o f Feed and D i g e s t a i n Ruminants. (P.M. Kennedy, Ed.). Occ. Pub. 1, Canadian S o c i e t y o f Animal S c i e n c e , Edmonton, A l b e r t a , Canada: 93-101. Murphy, M.R. and J.M. N i c o l e t t i . 1984. P o t e n t i a l r e d u c t i o n o f f o r a g e and rumen d i g e s t a p a r t i c l e s i z e by m i c r o b i a l a c t i o n . J . D a i r y S c i . 67: 1221-1226. N a t i o n a l R e s e a r c h C o u n c i l . 1978. N u t r i e n t requirements o f D a i r y C a t t l e . N a t i o n a l Academy o f S c i e n c e s , Washington, D.C. N i c h o l s , G. De La M.. 1966. Radio t r a n s m i s s i o n N.Z. J l . A g r i c . Res. 9: 468-473. O'Dogherty, M.J. 1982. A review o f r e s e a r c h Engng. Res. 27: 267-289.  o f sheep's jaw  on forage  movements.  chopping. J . A g r i c .  O'Dogherty, M.J. 1984. The d e s c r i p t i o n o f chop l e n g t h d i s t r i b u t i o n s from f o r a g e h a r v e s t e r s and a g e o m e t r i c a l s i m u l a t i o n model f o r d i s t r i b u t i o n g e n e r a t i o n . I n : Techniques i n P a r t i c l e S i z e A n a l y s i s o f Feed and D i g e s t a i n Ruminants. (P.M. Kennedy, Ed.). Occ. Pub. 1, Canadian S o c i e t y o f A n i m a l S c i e n c e , Edmonton, A l b e r t a , Canada: 62-75. O l t j e n , R.R., R.J. S i r n y and A.D. T i l l m a n . sheep. J . Anim. S c i . 21: 277-281.  1962.  P u r i f i e d d i e t studies  Osbourn, D.F., R.A. T e r r y , M.C. Spooner and R.M. Tetlow. 1981. Use o f p r o c e s s i n g to e x p l o r e the f a c t o r s a f f e c t i n g the d i g e s t i o n o f forage w a l l s . Anim, Feed S c i . and Tech. 6: 387-403.  with  cell  P a r k i n s o n , J.A. and S.E. A l l e n . 1975. A wet o x i d a t i o n procedure s u i t a b l e f o r the d e t e r m i n a t i o n o f n i t r o g e n and m i n e r a l n u t r i e n t s i n b i o l o g i c a l m a t e r i a l . Commun. S o i l S c i . and P l a n t A n a l . 6: 1-11. Pearce, G.R. 1965. Rumination i n sheep: I I . The r u m i n a t i o n . A u s t . J . A g r i c . Res. 16: 635.  -154-  circadian pattern  of  Pearce, G.R. and R.J. M o i r . 1964. Rumination i n sheep: I . The i n f l u e n c e o f r u m i n a t i o n and g r i n d i n g upon the passage and d i g e s t i o n o f f o o d . Aust. J . A g r i c . Res. 15: 635-644. Penning, P.D.. 1983. A t e c h n i q u e t o r e c o r d a u t o m a t i c a l l y some a s p e c t s o f g r a z i n g and r u m i n a t i n g b e h a v i o r i n sheep. Grass and F o r . S c i . 38: 89-96. Pond, K.R., W.C. E l l i s , J.H. M a t i s and J.P. T e l e f o r d . 1983. D e s c r i b i n g s i e v e d f o r a g e m a t e r i a l s : A new approach. J . Anim. S c i . 57, Supp. 1: 293-294. Pond, K.R., E.A. T o l l e y , W.C. E l l i s and J.H. M a t i s . 1984. A method f o r d e s c r i b i n g the weight d i s t r i b u t i o n o f p a r t i c l e s from s i e v e d f o r a g e . I n : Techniques i n P a r t i c l e S i z e A n a l y s i s o f Feed and D i g e s t a i n Ruminants. (P.M. Kennedy, E d . ) . Occ. Pub. 1, Canadian S o c i e t y o f Animal S c i e n c e , Edmonton, A l b e r t a , Canada: 123-133. Poppi, D.P., B.W. Norton, D.J. Minson and R.E. H e n d r i c k s e n . 1980. The V a l i d i t y o f the c r i t i c a l s i z e t h e o r y f o r p a r t i c l e s l e a v i n g the rumen. J . A g r i c . S c i . Camb. 94: 275-280. R e i d , C.S.W., M. U l y a t t and J.A. Munro. 1977. The p h y s i c a l breakdown o f f e e d d u r i n g d i g e s t i o n i n the rumen. Proc. N.Z. Soc. Anim. Prod. 37: 173. R e i d , C.S.W., A. John, M.J. U l y a t t , G.C. Waghorn and L.P. M i l l i g a n . 1979. Chewing and the P h y s i c a l breakdown o f f e e d i n sheep. Ann. Rech. V e t . 10: 205-207. Robles, A.Y., R.L. B e l y e a , F.A. Martz, M.F. Weiss. 1980. E f f e c t o f p a r t i c l e s i z e upon d i g e s t i b l e c e l l w a l l and r a t e o f i n v i t r o d i g e s t i o n o f a l f a l f a and o r c h a r d g r a s s f o r a g e s . J . Anim. S c i . 51: 783-790. R o b l e s , A.Y., R.L. B e l y e a , F.A. Martz, M.F. Weiss and R.W. Maus. 1981. Intake, d i g e s t i b i l i t y , r u m i n a l c h a r a c t e r i s t i c s and r a t e o f passage o f o r c h a r d g r a s s d i e t s f e d t o sheep. J . Anim. S c i . 53: 489-493 Rode, L.M., D.C. Weakley and L.D. S a t t e r . 1985. E f f e c t o f f o r a g e amount and p a r t i c l e s i z e i n d i e t s o f l a c t a t i n g d a i r y cows on s i t e o f d i g e s t i o n and m i c r o b i a l p r o t e i n s y n t h e s i s . Can. J . Anim. S c i . 65: 101-111. Rose, H.E. 1954. The Measurement o f P a r t i c l e S i z e i n Very F i n e Powders. Chemical P u b l i s h i n g Co. I n c . , New York. Ruckebush, Y. and L. Bueno. 1973. Un d i s p o s i t i f simple e t autonome d ' e n r e g i s t r e m e n t de l ' a c t i v i t e a l i m e n t a i r e chez l e s b o v i n s au paturage. Ann. Rech. V e t e r . 4: 627-636. S a n t i n i , F . J . , A.R. H a r d i e , N.A. Jorgensen and M.F. F i n n e r . 1983. Proposed use o f a d j u s t e d i n t a k e based on f o r a g e p a r t i c l e l e n g t h f o r c a l c u l a t i o n o f roughage indexes. J . D a i r y S c i . 66: 811-820.  -155-  Smith, L.W. and D.R. Waldo. 1969. Method o f s i z i n g f o r a g e c e l l w a l l p a r t i c l e s . J . D a i r y S c i . 52: 2051-2053. Smith, L.W., R.A. Erdman and E. Russek. 1984. E v a l u a t i o n o f the l o g a r i t h m i c normal d i s t r i b u t i o n and f o u r s i n g l e e x p o n e n t i a l d i s t r i b u t i o n s f o r d e s c r i b i n g c e l l w a l l p a r t i c l e s i z e . I n : Techniques i n P a r t i c l e S i z e A n a l y s i s o f Feed and D i g e s t a i n Ruminants. (P.M. Kennedy, E d . ) . Occ. Pub. 1, Canadian S o c i e t y o f Animal S c i e n c e , Edmonton, A l b e r t a , Canada: 83-92. Smith, L.W., B.T. Weinland, D.R. Waldo and E.C. L e f f e l . 1983. Rate o f p l a n t c e l l w a l l p a r t i c l e s i z e r e d u c t i o n i n the rumen. J . D a i r y S c i . 66: 2124-2136. Stobbs, T.H. and L . J . Cowper. 1972. Automatic measurement o f the jaw movements o f d a i r y cows d u r i n g g r a z i n g and r u m i n a t i o n . Trop. G r a s s l d . 6: 107-112. Sudweeks, E.M. and L.O. E l y . 1979. E v a l u a t i n g the p h y s i c a l form o f the d i e t i n ruminant n u t r i t i o n . D i s t i l l e r s Feed Res. C o u n c i l Proc. 34: 60-66. Sudweeks, E.M., M.E. McCullough, L.R. S i s k and S.E. Law. 1975. E f f e c t s o f c o n c e n t r a t e type and l e v e l and f o r a g e type on chewing time o f s t e e r s . J . Anim. S c i . 41: 219-224. Thomson, D.J., D.E. Beever, M.J. Latham, M.E. Sharpe and R.A. T e r r y . 1977. The e f f e c t o f i n c l u s i o n o f m i n e r a l s a l t s i n the d i e t on d i l y t i o n r a t e , the p a t t e r n o f rumen f e r m e n t a t i o n and c o m p o s i t i o n o f rumen m i c r o f l o r a . J . A g r i c . S c i . 23: 139. Uden, P. and P.J. Van Soest. 1982. The d e t e r m i n a t i o n o f d i g e s t a p a r t i c l e s i z e i n some h e r b i v o r e s . Anim. Feed S c i . Tech. 7: 35-44. Van Beukelen, P., Th. Wensing and H.J. Breukink. 1985. Some e x p e r i e n c e s w i t h the f e e d i n g o f chopped roughage to h i g h p r o d u c i n g d a i r y cows. E f f e c t s on chewing time, r u m i n a l f e r m e n t a t i o n , m i l k f a t p r o d u c t i o n and on b l o o d g l u c o s e and i n s u l i n l e v e l s . Z e i t s c h r i f t f u r T i e r p h y s i o l o g i e , T i e r e r n a h r u n g und F u t t e r m i t t e l k u n d e 53: 19-34. Waldern, D.E. 1971. A r a p i d m i c r o - d i g e s t i o n procedure d e t e r g e n t f i b e r . Can. J . Anim. S c i . 51: 67.  f o r n e u t r a l and a c i d  Waldo, D.R., L.W. Smith, E.L. Cox, B.T. Weinland and H.L. Lucas, J r . 1971. L o g a r i t h m i c normal d i s t r i b u t i o n f o r d e s c r i p t i o n o f s i e v e d f o r a g e m a t e r i a l s . J . D a i r y . S c i . 54: 1465-1469. W e i b u l l , W. 1951. A s t a t i s t i c a l d i s t r i b u t i o n f u n c t i o n o f wide a p p l i c a b i l i t y . J . A p p l . Mech. 18: 293-296. Welch, J.G. 1982. Rumination, P a r t i c l e s i z e and passage from the rumen. J . Anim. S c i . 54: 885-894.  -156-  Welch, J.G. and A.M. Smith. 1968. I n f l u e n c e o f f a s t i n g on r u m i n a t i o n a c t i v i t y i n sheep. J . Anim. S c i . 27: 1734-1737. Welch, J.G., and A.M. Smith. 1969a. I n f l u e n c e o f f o r a g e q u a l i t y on r u m i n a t i o n time i n sheep. J . Anim. S c i . 28: 813-818. Welch, J.G., and A.M. Smith. 1969b. E f f e c t o f v a r y i n g amounts o f f o r a g e i n t a k e on r u m i n a t i o n . J . Anim. S c i . 28: 827-830. Welch, J.G. and A.M. Smith. 1971. P h y s i c a l s t i m u l a t i o n o f r u m i n a t i o n a c t i v i t y . J . Anim. S c i . 33: 1118. Welch, J.G. and A.M. Smith. 1978. P a r t i c l e s i z e s p a s s e d from the rumen. J . Anim. S c i . 46: 309-312. Weston, R.H. and P.M. Kennedy. 1984. V a r i o u s a s p e c t s o f r e t i c u l o r u m e n d i g e s t i v e f u n c t i o n i n r e l a t i o n to d i e t and d i g e s t a p a r t i c l e s i z e . In: Techniques i n P a r t i c l e S i z e A n a l y s i s o f Feed and D i g e s t a i n Ruminants. (P.M. Kennedy, E d . ) . Occ. Pub. 1, Canadian S o c i e t y o f Animal S c i e n c e , Edmonton, A l b e r t a , Canada: 1-17. Yang, R . C , A. Kozak and J.H.G. Smith. 1978. The p o t e n t i a l o f W e i b u l l - t y p e f u n c t i o n s as f l e x i b l e growth c u r v e s . Can J . F o r . Res. 8: 424-431.  -157-  APPENDICES  APPENDIX A: PARTITIONING OF THE SUMS OF SQUARES FOR THE ANALYSIS OF INTAKE AND CHEWING BEHAVIOR IN THE DAIRY COW TRIAL (Reduced General Linear Hypothesis Models)  (a) T o t a l f e e d Source  intake: Degrees o f Freedom  Sums o f Squares  Mean Squares  F Value  Pr > F  8.062 0.036 11.056 0.003 2.436  9.43 0.04 12.93 0.00  0 .015 0 .842 0 .007 0 .954  Sums o f Squares  Mean Squares  F Value  Pr > F  596.106 87.440 44.038 14.680 33.525  17.78 2.61 1.31 0.44  0..001 0..123 0..266 0..516  Sums o f Squares  Mean Squares  F Value  Pr > F  29.260 8.592 72.107 12.586 6.126  Period Length % Hay Leng x Hay Error  1 1 1 1 19  8.062 0.036 11.056 0.003 46.280  Total  34  104.876  Time spent i d l e : Source  Degrees o f Freedom  Period Length % Hay Leng x Hay Error  1 1 1 1 19  596.106 87.440 44.038 14.680 636.984  Total  23  1379.248  Time spent Source  eating: Degrees o f Freedom  Period Length % Hay Leng x Hay Error  1 1 1 1 19  29.260 8.592 72.107 12.586 116.395  Total  23  238.940  -158-  ' 4.78 1.40 11.77 2.05  0..042 0,.251 0..003 0..168  APPENDIX A (cont'd)  (d) T o t a l time spent r u m i n a t i n g : Source  Degrees o f Freedom  Sums o f Squares  Mean Squares  F Value  Pr > F  0.113 13.365 100.901 10.283 8.132  0.01 1.64 12.41 1.26  0. 907 0. 215 0.,002 0.,275  Period Length % Hay Leng x Hay Error  1 1 1 1 19  0.113 13.365 100.901 10.283 154.512  Total  23  279.175  Total  time spent chewing ( e a t i n g  Source  Degrees o f Freedom  plus ruminating):  Sums o f Squares  Mean Squares  F Value  Pr > F  33.654 42.560 341.562 0.086 19.767  1.70 2.15 17.28 0.00  0 .208 0 .159 0 .001 0 .948  Sums o f Squares  Mean Squares  F Value  Pr > F  1.042 26.042 165.375 9.375 12.621  0.08 2.06 13.10 0.74  0 .777 0 .167 0 .002 0,.400  Period Length % Hay Leng x Hay Error  1 1 1 1 19  33.654 42.560 341.562 0.086 375.565  Total  23  793.427  Number o f b o l i Source  regurgitated: Degrees o f Freedom  Period Length % Hay Leng x Hay Error  1 1 1 1 19  1.042 26.042 165.375 9.375 239.792  Total  23  441.625  -159-  APPENDIX A ( c o n t ' d )  Time chewing p e r b o l u s r e g u r g i t a t e d :  Source  Degrees o f Freedom  Sums o f Squares  Mean Squares  F Value  Pr > F  0,.008 0,.020 0,.005 0..000 0..006 0..002  4,.16 10,.21 2 .72 0..06 2,.96  0..078 0..002 0..134 0.,809 0,,124  Period Animal Length % Hay Leng x Hay Error  1 11 1 1 1 8  0..008 0..225 0..005 0.,000 0.,006 0.,016  Total  23  0.,260  -160-  APPENDIX B  PARTITIONING OF THE SUMS OF SQUARES FOR THE ANALYSIS OF INTAKE AND CHEWING BEHAVIOR IN THE STEER TRIAL ( F u l l G e n e r a l L i n e a r H y p o t h e s i s Models)  feed intake:  (a) T o t a l Source  Degrees o f Freedom  Sums o f Squares  Period Animal Length BW Error  3 3 3 1 5  0.093 54.287 0.933 0.186 0.236  15  55.734  0  75  Total  Mean Squares  F Value  Pr > F  0.031 18.096 0.311 0.186 0.047  0.65 383.73 6.59 3.95  0 .614 0..000 0,.035 0,.104  Mean Squares  F Value  Pr > F  38.656 1210.910 213.000 124.460  1.58 49.50 8.71 7.80  0. 305 0. 000 0. 020 0. 038  Sums o f Squares  Mean Squares  F Value  Pr > F  3.110 113.698 3.039 5.064 1.016  3.06 112.92 2.99 4.98  0..130 0..000 0,.134 0..076  (b) Time spent i d l e : Source  Degrees o f Freedom  Period Animal Length BW Error  3 3 3 1 5  115.967 3632.728 638.998 190.768 122.302  15  4700.762  0  75  Total  Sums o f Squares  (c) Time spent e a t i n g : Source  Degrees o f Freedom  Period Animal Length BW Error  3 3 3 1 5  9.323 341.094 9.118 5.064 5.079  15  369.679  0  75  Total  -161-  APPENDIX B (cont'd)  (d) T o t a l time spent r u m i n a t i n g : Sums o f Squares  Source  Degrees o f Freedom  Period Animal Length BW Error  3 3 3 1 5  42.399 73.195 131.102 19.095 12.744  15  278.535  0  75  Total  time spent chewing ( e a t i n g  Total  Source  Degrees o f Freedom  Period Animal Length BW Error 0  75  Total  Number o f b o l i  14.133 24.398 43.700 19.095 2.549  5.55 9.57 17.15 7.49  0,.048 0..016 0..005 0,.041  Mean Squares  F Value  Pr > F  3 3 3 1 5  67.718 418.917 207.679 44.058 20.793  22.572 139.639 69.226 44.058 4.159  5.43 33.58 16.65 10.59  0 .050 0 .001 0 .005 0 .023  15  759.165  Sums o f Squares  Mean Squares  F Value  Pr > F  21.167 15.167 111.500 8.285 7.243  2.92 2.09 15.39 1.14  0..134 0.,220 0.,006 0.,334  regurgitated:  Period Animal Length BW Error  3 3 3 1 5  63.500 45.500 334.500 8.285 36.214  15  488.000  Total  Pr > F  Sums o f Squares  Degrees o f Freedom  75  F Value  plus ruminating):  Source  0  Mean Squares  -162-  APPENDIX B (cont'd)  Time chewing p e r b o l u s r e g u r g i t a t e d :  Sums o f Squares  Mean Squares  F Value  Pr > F  3 3 3 1 5  0.005 0.058 0.025 0.009 0.006  0.002 0.019 0.008 0.009 0.001  1.22 14.88 6.47 6.80  0..395 0..006 0..036 0,.048  15  0.103  Source  Degrees o f Freedom  Period Animal Length BW Error 0  75  Total  -163-  

Cite

Citation Scheme:

    

Usage Statistics

Country Views Downloads
United States 16 1
China 13 19
France 5 0
Canada 3 0
Iran 2 2
Philippines 2 0
Romania 1 0
Poland 1 0
City Views Downloads
Unknown 10 3
Beijing 9 0
Ashburn 5 0
Shenzhen 4 19
Sunnyvale 3 0
Redwood City 2 0
Montreal 2 0
Mountain View 2 0
Suceava 1 0
Ypsilanti 1 0
Tuscaloosa 1 0
Saint-Pie 1 0
Lima 1 0

{[{ mDataHeader[type] }]} {[{ month[type] }]} {[{ tData[type] }]}
Download Stats

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0096829/manifest

Comment

Related Items