Open Collections

UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Effects of feeding tallow protected with soybean meal or canola meal to dairy cows during the first 15… Vincente, Gail Richmond 1981

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1981_A6_7 V52.pdf [ 7.87MB ]
Metadata
JSON: 831-1.0095518.json
JSON-LD: 831-1.0095518-ld.json
RDF/XML (Pretty): 831-1.0095518-rdf.xml
RDF/JSON: 831-1.0095518-rdf.json
Turtle: 831-1.0095518-turtle.txt
N-Triples: 831-1.0095518-rdf-ntriples.txt
Original Record: 831-1.0095518-source.json
Full Text
831-1.0095518-fulltext.txt
Citation
831-1.0095518.ris

Full Text

E F F E C T S OF F E E D I N G TALLOW PROTECTED WITH SOYBEAN MEAL OR CANOLA MEAL TO DAIRY COWS DURING THE F I R S T 15 -WEEKS OF L A C T A T I O N by G A I L RICHMOND V I C E N T E B . S c , T h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , 1974 A T H E S I S SUBMITTED IN P A R T I A L F U L F I L M E N T OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF S C I E N C E i n THE F ACULTY OF GRADUATE S T U D I E S ( D e p a r t m e n t o f A n i m a l S c i e n c e , F a c u l t y o f A g r i c u l t u r a l S c i e n c e s ) We a c c e p t t h i s t h e s i s a s c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE U N I V E R S I T Y OF B R I T I S H COLUMBIA S e p t e m b e r 1981 © G a i l R i c h m o n d V i c e n t e , 1981 I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r an advanced degree a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e head o f my department o r by h i s o r h e r r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department o f ,Jrj'(ynail. .5n.finrP. The U n i v e r s i t y o f B r i t i s h C o l u m b i a 2075 Wesbrook P l a c e V ancouver, Canada V6T 1W5 Date i i ABSTRACT S o y b e a n m e a l - p r o t e c t e d t a l l o w h a s b e e n c o m m e r c i a l l y a v a i l a b l e i n C a n a d a f o r u s e i n d a i r y r a t i o n s , s i n c e 1975. T h e r e p o r t e d e f f e c t s o f f e e d i n g p r o t e c t e d t a l l o w t o d a i r y cows h a v e b e e n v a r i a b l e a n d t h e p r i c e s o f p r o t e c t e d t a l l o w s u p p l e m e n t s h a v e b e e n h i g h . I n v i e w o f t h e l o w e r c o s t o f c a n o l a m e a l r e l a t i v e t o s o y b e a n m e a l i n C a n a d a , a s t u d y was u n d e r t a k e n t o i n v e s t i g a t e t h e e f f i c a c y o f f e e d i n g p r o t e c t e d t a l l o w made e i t h e r f r o m s o y b e a n m e a l o r c a n o l a m e a l , t o d a i r y cows i n e a r l y l a c t a t i o n . S e c o n d l y , a c o m p a r i s o n was made b e t w e e n t h e s o y b e a n m e a l - p r o t e c t e d t a l l o w a n d t h e c a n o l a m e a l - p r o t e c t e d t a l l o w . T w e n t y - s e v e n cows f r o m t h e U n i v e r s i t y h e r d , c o m p r i s e d o f 12 f i r s t - c a l f H o l s t e i n h e i f e r s , 3 H o l s t e i n s i n t h e i r >2nd l a c t a t i o n , 4 A y r s h i r e h e i f e r s a n d 8 >2nd l a c t a t i o n A y r s h i r e s , w e r e u s e d i n a c o n t i n u o u s f e e d i n g t r i a l w h i c h was c o n d u c t e d f r o m d a y o f c a l v i n g u n t i l t h e e n d o f week 20 o f l a c t a t i o n . Cows we r e r a n d o m l y a s s i g n e d w i t h i n b r e e d a n d l a c t a t i o n c a t e g o r y (9 cows p e r t r e a t m e n t ) t o one o f 3 i s o n i t r o g e n o u s (16 % c r u d e p r o t e i n ) c o n c e n t r a t e s : a) no p r o t e c t e d t a l l o w ( c o n t r o l ) ; b) 8 % s o y b e a n m e a l - p r o t e c t e d t a l l o w ; o r c ) 8 % c a n o l a m e a l - p r o t e c t e d t a l l o w , w h i c h t h e y r e c e i v e d d u r i n g weeks 1-15 ( i n c l u s i v e ) . F r o m t h e b e g i n n i n g o f week 16 u n t i l t h e e n d o f week 20 a l l cows w e r e f e d a 16 % c r u d e p r o t e i n , p o s t - t r e a t m e n t c o n c e n t r a t e ( n o p r o t e c t e d t a l l o w ) . T h r o u g h o u t t h e 20-week t r i a l t h e r a t i o o f c o n c e n t r a t e s t o c u b e s o f f e r e d was m a i n t a i n e d a t 70:30 w i t h f e e d i n t a k e s b e i n g a d l i b i t u m . B e t w e e n weeks 13 a n d 16, 4 cows p e r t r e a t m e n t w e r e a s s i g n e d t o a d i g e s t i b i l i t y t r i a l i n v o l v i n g a 7-day t o t a l c o l l e c t i o n o f f a e c e s a n d u r i n e . P r o t e c t e d t a l l o w r a t i o n s p r o d u c e d s i g n i f i c a n t i n c r e a s e s o v e r t h e c o n t r o l r a t i o n (P<.05) i n t h e y i e l d s o f m i l k , 4 % f a t -c o r r e c t e d m i l k a n d m i l k f a t , a n d p r o t e c t e d t a l l o w r a t i o n s i n c r e a s e d t h e e f f i c i e n c i e s o f c o n v e r s i o n o f g r o s s e n e r g y , d i g e s t i b l e e n e r g y , c r u d e p r o t e i n a n d d i g e s t i b l e p r o t e i n t o m i l k , 4 % f a t - c o r r e c t e d m i l k , s o l i d s - c o r r e c t e d m i l k a n d m i l k e n e r g y ( P < . 0 5 ) . T h e a p p a r e n t d i g e s t i b i l i t y o f e t h e r e x t r a c t a n d t h e c o n c e n t r a t i o n o f p l a s m a n o n - e s t e r i f i e d f a t t y a c i d s w e r e s i g n i f i c a n t l y h i g h e r on r a t i o n s w i t h p r o t e c t e d t a l l o w ( P < . 0 5 ) . M i l k p r o t e i n % was s i g n i f i c a n t l y r e d u c e d b e l o w t h e c o n t r o l l e v e l w i t h r a t i o n s c o n t a i n i n g p r o t e c t e d t a l l o w a n d rumen a c e t a t e a n d t h e a c e t a t e : p r o p i o n a t e l e v e l s w e r e a l s o d e c r e a s e d . P r o t e c t e d t a l l o w r a t i o n s h a d no s i g n i f i c a n t e f f e c t on t h e i n t a k e s o f d r y m a t t e r , g r o s s e n e r g y , d i g e s t i b l e e n e r g y , c r u d e p r o t e i n o r d i g e s t i b l e p r o t e i n o r on t h e a p p a r e n t d i g e s t i b i l i t i e s o f d r y m a t t e r , o r g a n i c m a t t e r , g r o s s e n e r g y , n i t r o g e n , a c i d -d e t e r g e n t f i b r e , a s h , c a l c i u m , p h o s p h o r u s o r m a g n e s i u m ( P > . 0 5 ) . A l s o t h e y i e l d s o f s o l i d s - c o r r e c t e d m i l k , m i l k g r o s s e n e r g y a n d m i l k p r o t e i n , t h e p l a s m a g l u c o s e c o n c e n t r a t i o n a n d a v e r a g e d a i l y g a i n 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 , on r a t i o n s c o n t a i n i n g p r o t e c t e d t a l l o w , c o m p a r e d w i t h t h e c o n t r o l r a t i o n . 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 b e t w e e n t h e s o y b e a n m e a l - p r o t e c t e d t a l l o w r a t i o n a n d t h e c a n o l a m e a l - p r o t e c t e d t a l l o w r a t i o n f o r a n y p a r a m e t e r m e a s u r e d e x c e p t a p p a r e n t d i g e s t i b i l i t y o f e t h e r e x t r a c t w h i c h was s i g n i f i c a n t l y h i g h e r f o r t h e c a n o l a m e a l - p r o t e c t e d t a l l o w r a t i o n ( P < . 0 1 ) . i v T h e r e m o v a l o f p r o t e c t e d t a l l o w f r o m t h e r a t i o n d u r i n g w e eks 16-20 o f l a c t a t i o n , r e s u l t e d i n t h e m a i n t e n a n c e o f s i g n i f i c a n t l y h i g h e r e f f i c i e n c i e s o f c o n v e r s i o n o f d i e t a r y e n e r g y a n d p r o t e i n t o m i l k , 4 % f a t - c o r r e c t e d m i l k , s o l i d s -c o r r e c t e d m i l k a n d m i l k g r o s s e n e r g y f o r cows p r e v i o u s l y f e d p r o t e c t e d t a l l o w r a t i o n s c o m p a r e d t o t h e p o s t - c o n t r o l g r o u p ( P < . 0 1 ) . T h e r e w e r e no s i g n i f i c a n t d i f f e r e n c e s b e t w e e n t h e p o s t - c o n t r o l cows a n d p o s t - p r o t e c t e d t a l l o w cows f o r t h e i n t a k e s o f d r y m a t t e r , e n e r g y o r p r o t e i n , t h e y i e l d s o f m i l k , 4 % f a t -c o r r e c t e d m i l k , s o l i d s - c o r r e c t e d m i l k , m i l k g r o s s e n e r g y , m i l k f a t , o r l a c t o s e , o r p l a s m a g l u c o s e o r n o n - e s t e r i f i e d f a t t y a c i d c o n c e n t r a t i o n s ( P > . 0 5 ) . Th e o n l y d i f f e r e n c e s b e t w e e n t h e p o s t - s o y b e a n m e a l -p r o t e c t e d t a l l o w a n d t h e p o s t - c a n o l a m e a l - p r o t e c t e d t a l l o w r a t i o n s w e r e f o r t h e i n t a k e s o f d r y m a t t e r , g r o s s e n e r g y a n d c r u d e p r o t e i n f r o m c o n c e n t r a t e s , w h i c h were s i g n i f i c a n t l y l o w e r on t h e l a t t e r r a t i o n ( P < . 0 5 ) . Th e r e s u l t s o f t h i s s t u d y i n d i c a t e t h a t c a n o l a m e a l -p r o t e c t e d t a l l o w may be s u c c e s s f u l l y f e d i n p l a c e o f s o y b e a n m e a l - p r o t e c t e d t a l l o w t o d a i r y cows i n e a r l y l a c t a t i o n . V T A B L E OF CONTENTS ABSTRACT i i L I S T OF T A BLES v i i i L I S T OF FIGURES x ACKNOWLEDGEMENTS x i I . INTRODUCTION 1 I I . L I T E R A T U R E REVIEW 4 A. T h e F a t e Of D i e t a r y C o m p o n e n t s I n T h e Rumen 5 1. C a r b o h y d r a t e s 5 2. N i t r o g e n o u s Compounds 8 3. L i p i d s 14 a . H y d r o l y s i s 16 b. B i o h y d r o g e n a t i o n Of U n s a t u r a t e d F a t t y A c i d s .. 17 c . L i p i d B i o s y n t h e s i s 19 d . F e r m e n t a t i o n Of G l y c e r o l A n d G a l a c t o s e 21 B. U n p r o t e c t e d L i p i d s 21 C. P r o t e c t e d L i p i d s 22 1 . T e c h n o l o g y 22 2. P o l y u n s a t u r a t e d P r o t e c t e d L i p i d s 26 a . P o l y u n s a t u r a t e d M i l k A n d D a i r y P r o d u c t s 27 b . P o l y u n s a t u r a t e d Body L i p i d s 28 3. H i g h E n e r g y P r o t e c t e d L i p i d s 29 a . M i l k Y i e l d 29 b . M i l k C o m p o s i t i o n 35 i . F a t 35 i i . P r o t e i n 36 i i i . L a c t o s e 37 c . M i l k F a t S y n t h e s i s 38 i . I n t r a m a m m a r y F a t t y A c i d S y n t h e s i s 38 i i . S o u r c e s Of C a r b o n 39 i i i . Mammary U p t a k e A n d D e s a t u r a t i o n Of P l a s m a F a t t y A c i d s 41 i v . C o n t r i b u t i o n Of P l a s m a L i p i d s T o M i l k F a t 42 v . T h e I n f l u e n c e Of P r o t e c t e d Or U n p r o t e c t e d L i p i d s On T h e Y i e l d A n d P e r c e n t a g e Of M i l k F a t 42 v i . Rumen M i c r o b i a l F a t t y A c i d S y n t h e s i s ... 43 v i i . T h e o r i e s On D e p r e s s e d F a t t y A c i d S y n t h e s i s 44 d . F e e d U t i l i z a t i o n And G r o w t h P a r a m e t e r s 46 i . I n t a k e s 46 i i . E f f i c i e n c i e s 48 i i i . A p p a r e n t D i g e s t i b i l i t i e s 48 I I I . EXPERIMENTAL S T U D I E S 51 A. M a t e r i a l s A n d M e t h o d s 51 1 . F e e d i n g T r i a l 51 a . A n i m a l s 51 b . T r e a t m e n t s 52 i . P e r i o d I - T r e a t m e n t P e r i o d ( w e eks 1-15) . 52 i i . P e r i o d I I - P o s t - t r e a t m e n t P e r i o d ( w e e k s 16-20) 54 i i i . G e n e r a l M a i n t e n a n c e A n d S a m p l e C o l l e c t i o n 55 v i c . D i g e s t i b i l i t y T r i a l s 57 2. C h e m i c a l A n a l y s i s 59 a . M i l k 59 b. F e e d s t u f f s , F a e c e s , U r i n e 59 i . D r y M a t t e r 60 i i . C o m b u s t i b l e E n e r g y s 60 i i i . E t h e r E x t r a c t 61 i v . Wet O x i d a t i o n 61 v . N i t r o g e n 61 v i . A c i d D e t e r g e n t F i b r e 61 v i i . A s h ( T o t a l ) 62 v i i i . C a l c i u m 62 i x . P h o s p h o r u s 62 x. M a g n e s i u m 63 c . Rumen V o l a t i l e F a t t y A c i d s 63 i . P r e p a r a t i o n 63 i i . G a s L i q u i d C h r o m a t o g r a p h y ( G . L . C . ) 65 d. B l o o d P l a s m a 65 i . G l u c o s e 65 i i . N o n - E s t e r i f i e d F a t t y A c i d s 66 3. S t a t i s t i c a l A n a l y s i s 66 B. R e s u l t s 69 1 . P e r i o d I 69 a . R a t i o n C h e m i c a l A n a l y s i s 69 b. I n t a k e s 70 c . A p p a r e n t D i g e s t i b i l i t y C o e f f i c i e n t s 75 d . U r i n a r y N i t r o g e n 78 e. P r o d u c t i o n P a r a m e t e r s 79 i . M i l k A n d M i l k E n e r g y 79 i i . M i l k C o m p o n e n t P e r c e n t a g e s 81 i i i . M i l k C o m p o n e n t Y i e l d s 82 f . E f f i c i e n c y R a t i o s 85 i . E n e r g y 85 i i . P r o t e i n 89 g. A v e r a g e D a i l y G a i n s 93 h . B l o o d M e t a b o l i t e s 94 i . G l u c o s e 94 i i . N o n - E s t e r i f i e d F a t t y A c i d s 95 i . Rumen V o l a t i l e F a t t y A c i d s 97 2. P e r i o d I I 98 a . I n t a k e s 98 b. P r o d u c t i o n P a r a m e t e r s 100 i . M i l k A n d M i l k E n e r g y 100 i i . M i l k C o m p o s i t i o n 103 c . E f f i c i e n c y R a t i o s 106 d . B l o o d M e t a b o l i t e s 109 C. D i s c u s s i o n 111 1 . P e r i o d I 111 a . P r o t e c t e d T a l l o w S u p p l e m e n t s 111 b. R a t i o n C o m p o s i t i o n 112 c . I n t a k e s 112 d . A p p a r e n t D i g e s t i b i l i t i e s 115 e. U r i n a r y N i t r o g e n 118 f . P r o d u c t i o n P a r a m e t e r s 119 v i i i . M i l k A n d M i l k E n e r g y 119 i i . M i l k C o m p o s i t i o n 122 g. E f f i c i e n c y R a t i o s 129 i . E n e r g y 129 i i . P r o t e i n 130 h . A v e r a g e D a i l y G a i n 130 i . B l o o d M e t a b o l i t e s 131 j . Rumen V o l a t i l e F a t t y A c i d s 132 2. P e r i o d I I 132 a . I n t a k e s 132 b . P r o d u c t i o n P a r a m e t e r s ... 133 i . M i l k A n d M i l k E n e r g y 133 i i . M i l k C o m p o s i t i o n 134 c . E f f i c i e n c y R a t i o s 135 D. Summary A n d C o n c l u s i o n s 136 I V . BIBLIOGRAPHY 139 V. APPENDIX 154 v i i i L I S T OF T A B L E S T A B L E 1. SUMMARY OF PRODUCTIVE RESPONSES TO PROTECTED TALLOW FROM THE L I T E R A T U R E 30 T A B L E 2. PROTECTED TALLOW COMPOSITIONS(D.M.B.) - PERIOD I 53 T A B L E 3. CONCENTRATE COMPOSITIONS (D.M.B.) - PERIOD I 54 T A B L E 4. CHEMICAL ANALYSIS OF F E E D S T U F F S (D.M.B.) - PERIOD I 69 T A B L E 5. PREDICTED MEAN D A I L Y INTAKES PER COW (D.M.B.) -PERIOD I 71 T A B L E 6. C O E F F I C I E N T S OF DETERMINATION FOR INTAKES -PERIOD I 74 T A B L E 7. PREDICTED MEAN % APPARENT D I G E S T I B I L I T I E S (D.M.B. ) - PERIOD I 76 T A B L E 8. C O E F F I C I E N T S OF DETERMINATION FOR APPARENT D I G E S T I B I L I T Y V A R I A B L E S 77 T A B L E 9. URINARY VOLUME AND NITROGEN EXCRETION: D I G E S T I B I L I T Y T R I A L 79 T A B L E 10. PREDICTED MEAN D A I L Y , PER COW Y I E L D S OF MILK AND MILK ENERGY - PERIOD I 80 T A B L E 11. PREDICTED MEAN D A I L Y MILK COMPONENT PERCENTAGES AND Y I E L D S - PERIOD I 82 T A B L E 12. C O E F F I C I E N T S OF DETERMINATION FOR MILK OUTPUTS .. 84 T A B L E 13. PREDICTED MEAN MILK OUTPUT/G.E. INPUT E F F I C I E N C Y RATIOS - PERIOD I 86 T A B L E 14. PREDICTED MEAN MILK OUTPUT/D.E. INPUT E F F I C I E N C Y RATIOS - PERIOD I 87 T A B L E 15. C O E F F I C I E N T S OF DETERMINATION FOR ENERGY E F F I C I E N C Y RATIOS - PERIOD 1 88 T A B L E 16. PREDICTED MEAN MILK O U T P U T / C P . INPUT E F F I C I E N C Y RATIOS - PERIOD I 89 T A B L E 17. PREDICTED MEAN MILK OUTPUT/D.P. INPUT E F F I C I E N C Y RATIOS - PERIOD I 90 T A B L E 18. C O E F F I C I E N T S OF DETERMINATION FOR PROTEIN E F F I C I E N C Y RATIOS - PERIOD I 92 T A B L E 19. PREDICTED MEAN AVERAGE D A I L Y GAINS - PERIOD I ... 93 T A B L E 20. C O E F F I C I E N T S OF DETERMINATION FOR A.D.G. PERIOD I 94 T A B L E 2 1 . PREDICTED MEAN PLASMA M E T A B O L I T E CONCENTRATIONS -PERIOD I 95 T A B L E 22. C O E F F I C I E N T S OF DETERMINATION FOR BLOOD METABOLITES - PERIOD I 96 T A B L E 2 3 . MOLAR PERCENTAGES OF RUMEN V O L A T I L E F A T T Y ACIDS -PERIOD I 97 T A B L E 24. PREDICTED MEAN D A I L Y INTAKES PER COW (D.M.B.) -PERIOD I I 99 T A B L E 2 5 . C O E F F I C I E N T S OF DETERMINATION FOR INTAKES PERIOD I I 101 T A B L E 26. PREDICTED MEAN D A I L Y , PER COW Y I E L D S OF MILK AND MILK ENERGY - PERIOD I I 102 T A B L E 2 7 . PREDICTED MEAN D A I L Y MILK COMPONENT PERCENTAGES AND Y I E L D S - PERIOD I I 104 T A B L E 28. C O E F F I C I E N T S OF DETERMINATION FOR D A I L Y MILK i x Y I E L D S - PERIOD I I 105 T A B L E 29. PREDICTED MEAN MILK OUTPUT/G.E. INPUT E F F I C I E N C Y RATIOS - PERIOD I I 106 T A B L E 30. PREDICTED MEAN MILK O U T P U T / C P . INPUT E F F I C I E N C Y RATIOS - PERIOD I I 107 T A B L E 31. C O E F F I C I E N T S OF DETERMINATION FOR E F F I C I E N C Y RATIOS - PERIOD I I 108 T A B L E 32. PREDICTED MEAN PLASMA M E T A B O L I T E CONCENTRATIONS -PERIOD I I 110 T A B L E 33. C O E F F I C I E N T S OF DETERMINATION FOR BLOOD . METABOLITES - PERIOD I I 110 T A B L E I . PREDICTED MEANS AND STANDARD ERRORS FOR S I G N I F I C A N T SOURCES OF V A R I A T I O N : INTAKES AND OUTPUTS -PERIOD I 155 T A B L E I I . PREDICTED MEANS AND STANDARD ERRORS: MILK F A T % - PERIOD 156 T A B L E I I I . PREDICTED MEANS AND STANDARD ERRORS FOR S I G N I F I C A N T SOURCES OF V A R I A T I O N : E F F I C I E N C Y RATIOS -PERIOD I 157 T A B L E I V . PREDICTED MEANS AND STANDARD ERRORS FOR S I G N I F I C A N T SOURCES OF V A R I A T I O N : APPARENT ETHER EXTRACT D I G E S T I B I L I T Y - PERIOD I 158 T A B L E V. PREDICTED MEAN % APPARENT D I G E S T I B I L I T I E S (DRY MATTER B A S I S ) : C O L L E C T I O N - DAYS 1-4 159 T A B L E V I . PREDICTED MEANS AND STANDARD ERRORS FOR S I G N I F I C A N T SOURCES OF V A R I A T I O N : BLOOD ME T A B O L I T E S -PERIOD I 160 T A B L E V I I . PREDICTED MEANS AND STANDARD ERRORS FOR S I G N I F I C A N T SOURCES OF V A R I A T I O N : INTAKES AND OUTPUTS -PERIOD I I , 161 T A B L E V I I I . PREDICTED MEANS AND STANDARD ERRORS FOR S I G N I F I C A N T SOURCES OF V A R I A T I O N : ENERGY E F F I C I E N C Y RATIOS - PERIOD I I 162 T A B L E I X . PREDICTED MEANS AND STANDARD ERRORS FOR S I G N I F I C A N T SOURCES OF V A R I A T I O N : PROTEIN E F F I C I E N C Y RATIOS - PERIOD I I 163 X L I S T OF FIGURES F i g u r e 1. P a t h w a y s I n T h e Rumen B e t w e e n C a r b o h y d r a t e s A n d P y r u v a t e 6 F i g u r e 2. T h e S t e p s B e t w e e n P y r u v a t e A n d T h e V o l a t i l e F a t t y A c i d s 8 F i g u r e 3. T h e F l o w Of N i t r o g e n I n T h e Rumen 11 F i g u r e 4. U n s a t u r a t e d F a t t y A c i d s : P o s i t i o n a l I s o m e r s 18 F i g u r e 5. U n s a t u r a t e d F a t t y A c i d s : C i s A n d T r a n s I s o m e r s .. 19 F i g u r e 6. E x a m p l e s Of B r a n c h e d - c h a i n F a t t y A c i d s F o u n d I n R u m i n a n t L i p i d s , W h i c h A r e Of M i c r o b i a l O r i g i n 20 F i g u r e 7. M e t a b o l i c P a t h w a y s P r e s e n t I n M o n o g a s t r i c s B u t A b s e n t I n R u m i n a n t s 40 F i g u r e 8: M i c r o - D i s t i l l a t i o n A p p a r a t u s 64 x i ACKNOWLEDGEMENTS I w o u l d l i k e t o t a k e t h i s o p p o r t u n i t y t o t h a n k some o f t h e many p e o p l e whose v a l u a b l e a s s i s t a n c e e n a b l e d t h e s u c c e s s f u l c o m p l e t i o n o f t h i s t h e s i s . I am g r a t e f u l t o D r . C R . K r i s h n a m u r t i f o r h i s g u i d a n c e a n d a d v i c e t h r o u g h o u t t h e t h e s i s . I w o u l d a l s o l i k e t o e x p r e s s my a p p r e c i a t i o n t o D r . J . A . S h e l f o r d f o r h i s e n t h u s i a s t i c e n c o u r a g e m e n t a n d h e l p , p a r t i c u l a r l y d u r i n g t h e a n i m a l t r i a l s . S p e c i a l t h a n k s a r e e x t e n d e d t o D r s . L . J . F i s h e r a n d W.D. K i t t s f o r t h e i r r e v i e w o f t h i s t h e s i s . A d d i t i o n a l t h a n k s a r e due t o D r . R.G. P e t e r s o n f o r h i s a d v i c e on t h e s t a t i s t i c a l d e s i g n a n d a n a l y s i s , t o M r s . M. S t r i k e r f o r c o m p u t e r p r o g r a m m i n g a s s i s t a n c e , t o Mr. W. S l a c k f o r h i s h e l p w i t h h a n d l i n g o f t h e a n i m a l s , a n d t o Mr. G. G a l z y f o r o p e r a t i n g t h e G.L.C. a n d A.A. T h i s s t u d y was p a r t i a l l y s u p p o r t e d b y f u n d s p r o v i d e d by A l t a L i p i d s C a n a d a L t d . x i i DEDICATION Eu d e d i c o i s t o p r a meu marido Remigio p o l ' a p a c i e n c i a e axuda que continuamente me deu 1 I . INTRODUCTION The h i g h p r o d u c i n g d a i r y cow i s commonly f o r c e d i n t o a s t a t e o f n e g a t i v e e n e r g y b a l a n c e d u r i n g t h e e a r l y s t a g e s o f l a c t a t i o n . E n e r g y e x p e n d i t u r e s r e q u i r e d f o r m i l k p r o d u c t i o n a n d b o d y g r o w t h may e x c e e d e n e r g y i n t a k e , t h e l a t t e r b e i n g i n f l u e n c e d by a p p e t i t e , g u t - f i l l - c a p a c i t y a n d r a t i o n n u t r i e n t d e n s i t y . I m m e d i a t e l y a f t e r p a r t u r i t i o n h o r m o n a l l e v e l s may l i m i t a p p e t i t e a n d t h e r e b y s e v e r e l y r e s t r i c t e n e r g y i n p u t r e l a t i v e t o o u t p u t . T h e r e a f t e r , t h e p r o b l e m o f i n s u f f i c i e n t e n e r g y i n t a k e i s l a r g e l y due t o l i m i t a t i o n s o f g u t - f i l l c a p a c i t y i n c o n j u n c t i o n w i t h r e s t r a i n t s on maximum e n e r g y d e n s i t y i n r a t i o n s f o r m u l a t e d t o p r o v i d e a d e q u a t e q u a n t i t i e s o f d i e t a r y f i b r e . T h e cow h a s a t r e m e n d o u s c a p a c i t y t o c o m p e n s a t e f o r a n e g a t i v e e n e r g y b a l a n c e b y m o b i l i z i n g b o d y r e s e r v e s w h i c h a r e r e s t o r e d l a t e r i n l a c t a t i o n when demands f o r m i l k p r o d u c t i o n a r e r e d u c e d a n d a p p e t i t e h a s i m p r o v e d . I f w e i g h t l o s s i s e x c e s s i v e , h o w e v e r , m e t a b o l i c d i s o r d e r s ( e g . k e t o s i s ) a n d f e r t i l i t y p r o b l e m s may e n s u e . U t i l i z a t i o n o f e n e r g y m o b i l i z e d f r o m b o d y s t o r e s i s l e s s e f f i c i e n t t h a n u s i n g e n e r g y s u p p l i e d d i r e c t l y by t h e d i e t . F u r t h e r m o r e , i n a d e q u a t e e n e r g y i n t a k e d u r i n g e a r l y l a c t a t i o n may i n h i b i t f u l l e x p r e s s i o n o f t h e cow's g e n e t i c p o t e n t i a l , c a u s i n g a r e d u c t i o n i n p e a k m i l k y i e l d a n d c o n s e q u e n t l y a l o w e r e d t o t a l l a c t a t i o n y i e l d . U l t i m a t e l y t h i s l a c k o f e n e r g y i n t a k e r e p r e s e n t s c o n s i d e r a b l e e c o n o m i c l o s s e s t o t h e d a i r y p r o d u c e r . ' P r o t e c t e d l i p i d s ' , o r l i p i d s w h i c h h a v e b e e n t r e a t e d s u c h 2 t h a t t h e y r e s i s t m i c r o b i a l d e g r a d a t i o n i n t h e r u m i n o r e t i c u l u m b u t a r e s u b s e q u e n t l y a v a i l a b l e f o r d i g e s t i o n a n d a b s o r p t i o n i n t h e s m a l l i n t e s t i n e , h a v e b e e n u s e d t o i n c r e a s e e n e r g y d e n s i t y i n r a t i o n s w h i c h s t i l l s a t i s f y f i b r e r e q u i r e m e n t s . I n 1975, p r o t e c t e d l i p i d s u p p l e m e n t s became c o m m e r c i a l l y a v a i l a b l e i n C a n a d a , f o r u s e i n d a i r y r a t i o n s . B a s i c a l l y t h e p r e p a r a t i o n o f a p r o t e c t e d l i p i d r e q u i r e s s o u r c e s o f p r o t e i n , l i p i d , a l k a l i a n d f o r m a l d e h y d e . T h e f i r s t p r o t e c t e d l i p i d s m a n u f a c t u r e d i n C a n a d a u s e d s o y b e a n m e a l a s t h e p r o t e i n s o u r c e . Due t o t h e f a c t t h a t t h e s i t e o f t h e m a n u f a c t u r i n g p l a n t was i n W e s t e r n C a n a d a , t h e most e c o n o m i c a l s o u r c e o f s o y b e a n m e a l was f r o m t h e U.S. I n t h e s p r i n g o f 1976 t h e r e was a s u d d e n r i s e i n t h e p r i c e o f s o y b e a n m e a l i n N o r t h A m e r i c a , w h i c h s t a r t e d a n u p w a r d t r e n d t h a t p e a k e d one y e a r l a t e r . I n a d d i t i o n , t h e i n c r e a s e d s o y b e a n m e a l p r i c e was m a g n i f i e d by t h e w e a k e n i n g o f t h e C a n a d i a n d o l l a r r e l a t i v e t o i t s A m e r i c a n c o u n t e r p a r t . I n t h e q u e s t f o r a l e s s e x p e n s i v e s o u r c e o f p r o t e i n , t h e m e a l f r o m c a n o l a , w h i c h i s g rown e x t e n s i v e l y i n C a n a d a , was c o n s i d e r e d t o be a p o t e n t i a l a l t e r n a t i v e . T h e p r e s e n t s t u d y was u n d e r t a k e n t o c o m p a r e p r o t e c t e d t a l l o w s u p p l e m e n t s , made e i t h e r w i t h s o y b e a n m e a l ( G l y c i n e max) o r c a n o l a m e a l ( B r a s s i c a c a m p e s t r i s ) , when f e d t o d a i r y cows i n e a r l y l a c t a t i o n . T h e c o m p a r i s o n was b a s e d on t h e f o l l o w i n g p a r a m e t e r s : m i l k y i e l d a n d c o m p o s i t i o n ; f e e d i n t a k e ; a p p a r e n t d i g e s t i b i l i t i e s o f d r y m a t t e r , o r g a n i c m a t t e r , e n e r g y , n i t r o g e n , e t h e r e x t r a c t , a c i d d e t e r g e n t f i b r e , a s h , c a l c i u m , p h o s p h o r u s a n d m a g n e s i u m ; e f f i c i e n c i e s o f p r o d u c t i o n ; b o d y w e i g h t s ; rumen 3 v o l a t i l e f a t t y a c i d s ; a n d p l a s m a g l u c o s e a n d n o n - e s t e r i f i e d f a t t y a c i d s . I n o r d e r t o p l a c e t h e r e s u l t s o f t h e p r e s e n t s t u d y i n t h e p r o p e r p e r s p e c t i v e , a r e v i e w o f t h e m e t a b o l i s m o f d i e t a r y c o m p o n e n t s w i t h i n t h e rumen a n d a b a c k g r o u n d t o t h e d e v e l o p m e n t a n d u s e o f p r o t e c t e d l i p i d s i s p r e s e n t e d . 4 I I . L I T E R A T U R E REVIEW W h a t s o e v e r p a r t e t h t h e h o o f , a n d i s c l o v e n f o o t e d , a n d c h e w e t h t h e c u d , among t h e b e a s t s , t h a t s h a l l y e e a t . L e v i t i c u s 11:3 E v e n a s e a r l y a s i n b i b l i c a l t i m e s t h e c h a r a c t e r i s t i c s p e c u l i a r t o t h e r u m i n a n t h a v e p l a c e d i t i n a c a t e g o r y a l l o f i t s own i n t e r m s o f i t s i m p o r t a n c e t o man. T o d a y , t h e u n i q u e n e s s o f t h e d i g e s t i v e p h y s i o l o g y a n d m e t a b o l i s m o f t h e r u m i n a n t w a r r a n t s t h a t i t be t r e a t e d a s a s t u d y , c o m p l e t e i n i t s e l f . R u m i n a n t s , o r e v e n - t o e d , h o o v e d mammals o f t h e o r d e r A r t i o d a c t y l a a n d s u b o r d e r R u m i n a n t i a ( m e a n i n g c u d - c h e w i n g ) r e p r e s e n t t h e m o s t i m p o r t a n t g r o u p o f h e r b i v o r e s i n t e r m s o f t h e nu m b e r s o f mammals e x i s t i n g t o d a y , w h e t h e r d o m e s t i c o r w i l d ( C h u r c h , 1 9 7 0 ) . T h e u n i q u e n e s s a s c r i b e d t o t h e d i g e s t i v e p h y s i o l o g y a n d m e t a b o l i s m o f r u m i n a n t s i s l a r g e l y due t o t h e i n p u t o f 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 s p r i o r t o t h e i r g a s t r i c a n d s m a l l -i n t e s t i n a l d i g e s t i o n , a n d a b s o r p t i o n . I t i s o n l y w i t h a k n o w l e d g e o f t h e m e c h a n i s m s o f a c t i o n o f t h e rumen m i c r o o r g a n i s m s t h a t we may u n d e r s t a n d t h e f u n c t i o n i n g o f t h e r u m i n a n t a n d i n t h i s way p r e p a r e o u r s e l v e s f o r t h e c h a l l e n g i n g t a s k o f m a n a g i n g r u m i n a n t p r o d u c t i o n a n d / o r m a n i p u l a t i n g r u m i n a n t p r o d u c t i v i t y . 5 A. The F a t e o f D i e t a r y C o m p o n e n t s i n t h e Rumen 1. C a r b o h y d r a t e s T h e m a j o r c a r b o h y d r a t e s f o u n d i n t h e d i e t o f d o m e s t i c r u m i n a n t s i n c l u d e : c e l l u l o s e , h e m i c e l l u l o s e , p e c t i n s , s t a r c h e s , d e x t r a n s , f r u c t a n s a n d s o l u b l e c a r b o h y d r a t e s i n c l u d i n g m o n o s a c c h a r i d e s a n d d i s a c c h a r i d e s ( C h u r c h , 1 9 7 0 ) . Numerous s p e c i e s o f m i c r o o r g a n i s m s a r e i n v o l v e d w h i c h p a r t i c i p a t e s u c c e s s i v e l y a s t h e d e p o l y m e r i z a t i o n o f c e l l u l o s e p r o c e e d s i n v i v o ( A n n i s o n a n d L e w i s , 1 9 5 9 ) . A l l o t h e r d i e t a r y c a r b o h y d r a t e s p r e s e n t i n t h e rumen a r e a l s o d i g e s t e d b y b a c t e r i a e x i s t i n g i n s y m b i o s i s w i t h p r o t o z o a a n d w i t h e a c h o t h e r a n d w o r k i n g s y s t e m a t i c a l l y t o d i g e s t a p a r t i c u l a r s u b s t r a t e . U l t i m a t e l y a l l c a r b o h y d r a t e s s u c c e s s f u l l y d e g r a d e d w i t h i n t h e rumen, a r e c o n v e r t e d t o p y r u v a t e ( L e n g , 1 9 7 0 ) . F i g u r e 1 shows t h e m a j o r i n t e r m e d i a r y p r o d u c t s i n t h e d i g e s t i o n o f c a r b o h y d r a t e s t o p y r u v a t e w i t h i n t h e rumen. D i g e s t i o n o f c a r b o h y d r a t e s by rumen m i c r o o r g a n i s m s i n v o l v e s t h e i r d e g r a d a t i o n t o some o r a l l o f t h e f o l l o w i n g p r i m a r y f e r m e n t a t i o n p r o d u c t s : f o r m a t e , a c e t a t e , p r o p i o n a t e , b u t y r a t e , l a c t a t e a n d s u c c i n a t e ; h y d r o g e n , c a r b o n d i o x i d e a n d m e t h a n e ; e t h a n o l a n d m e t h a n o l ( H u n g a t e , 1 9 6 6 ) . A c e t i c , p r o p i o n i c a n d b u t y r i c a c i d s , c a r b o n d i o x i d e a n d m e t h a n e a r e f i n a l p r o d u c t s o f m i c r o b i a l d e g r a d a t i o n o f c a r b o h y d r a t e s . H o w e v e r , h y d r o g e n , e t h a n o l a n d f o r m i c , l a c t i c a n d s u c c i n i c a c i d s a r e i n t e r m e d i a t e s w h i c h i n t u r n a r e c o n v e r t e d t o m e t h a n e ( H u n g a t e , 1 9 6 6 ) . L a c t i c a c i d i s c o n v e r t e d t o a c e t i c 6 STARCH CELLULOSE PECTINS HEMICELLULOSE 1 anhydro- xylo-poly-glucose galacturonic oligosaccharide chains acid maltose 4 xylobiose I cellobiose galacturonic xylose(and other acid V glucose, glucose-1-P glucose-6-P fructose-6-P fructose-1-6-P dihydroxy-^^glyceraldehyde-3-P acetone-P I |[2H] [ 1,3 di-P-glycerate 1 3-P-glycerate i 2-P-glycerate 1 phosphoenolpyruvate I PYRUVATE Figure 1. Pathways in the rumen between carbohydrates and pyruvate. From Leng (1970). 7 a n d p r o p i o n i c a c i d s ( H o b s o n , 1 9 7 1 ) . S u c c i n i c a c i d i s d e c a r b o x y l a t e d t o p r o p i o n i c a c i d a n d c a r b o n d i o x i d e ( A n n i s o n a n d L e w i s , 1 9 5 9 ) . I s o v a l e r i c a n d i s o b u t y r i c a c i d s n o r m a l l y r e s u l t f r o m d e a m i n a t i o n o f l e u c i n e a n d v a l i n e , r e s p e c t i v e l y ( E l - S h a z l y , 1 9 5 2 ) . F i g u r e 2 o u t l i n e s t h e s t e p s b e t w e e n p y r u v a t e a n d t h e f i n a l p r o d u c t s o f r u m i n a l d i g e s t i o n o f c a r b o h y d r a t e s , t h e v o l a t i l e f a t t y a c i d s ( V F A s ) . T h e V F A s p r o d u c e d i n t h e rumen a r e a l m o s t c o m p l e t e l y a b s o r b e d i n t o t h e b l o o d s t r e a m t h r o u g h t h e rumen e p i t h e l i u m ( H o b s o n , 1 9 7 1 ) . P e n n i n g t o n ( 1 9 5 2 ) showed t h a t t h e rumen e p i t h e l i a l t i s s u e m e t a b o l i z e d b u t y r i c a n d a c e t i c a c i d s t o k e t o n e b o d i e s ( m o s t l y a c e t o a c e t a t e i n t h e c a s e o f b u t y r i c a c i d ) . No k e t o n e b o d i e s w e r e f o r m e d i n rumen e p i t h e l i u m f r o m p r o p i o n i c a c i d . C a r b o h y d r a t e s p r o v i d e t h e p r i m a r y s o u r c e o f e n e r g y f o r b o t h t h e rumen o r g a n i s m s a n d t h e h o s t a n i m a l . S t u d i e s w i t h s h e e p f e d a w i d e r a n g e o f f o r a g e r a t i o n s i n d i c a t e d t h a t 5 7 - 7 7 % o f t h e d a i l y m e t a b o l i z a b l e e n e r g y i n t a k e was p r o v i d e d by t h e V F A s v i a t h e i r o x i d a t i o n ( S e e l e y e t a l . , 1969; H o b s o n , 1 9 7 1 ) . 8 CARBOHYDRATE H ATP +2H „malate. oxaloacetate acetyl-CoA ^ ^ a c e t o -acetyl-CoA 2H lactate C1 butyryl-CoA I ACETATE BUTYRATE -H20 \ ^ fumarate + 2H\ succinate 4 succinyl-CoA y methylma1ony1* -CoA acrylate propionyl-CoA PROPIONATE Figure 2. The steps between pyruvate and the v o l a t i l e fatty acids, occurring within the rumen. From Hungate (1966). 2. Nitrogenous Compounds The range of nitrogenous compounds which the ruminant may encounter in the diet include: nucleoproteins (containing purine and pyrimidine bases); proteins (including those associated with 9 p l a n t c h l o r o p l a s t s , o i l s e e d m e a l s a f t e r e x t r a c t i o n , a n d c e r e a l s e e d s ) ( A n n i s o n a n d L e w i s , 1 9 5 9 ) ; n o n - p r o t e i n n i t r o g e n c o m p o u n d s s u c h a s a m i n o a c i d s , p e p t i d e s , a m i d e s , a m i n e s , v o l a t i l e a m i n e s , ammonium s a l t s , n i t r a t e s , n i t r i t e s , u r e a a n d b i u r e t ( C h u r c h , 1 9 7 0 ) . N i t r o g e n o u s c o m p o u n d s e n t e r i n g t h e rumen v i a t h e s a l i v a may i n c l u d e : m u c o p r o t e i n s , e p i t h e l i a l c e l l s s h e d f r o m t h e m o u t h a n d r e c y c l e d u r e a f r o m t h e l i v e r ( A n n i s o n a n d L e w i s , 1959; Rook a n d Thomas, 1969; M e r c e r a n d A n n i s o n , 1 9 7 6 ) . The e x t e n t t o w h i c h d i e t a r y p r o t e i n i s b r o k e n down by rumen m i c r o o r g a n i s m s d e p e n d s on t h e c h e m i c a l a n d p h y s i c a l n a t u r e o f t h e p r o t e i n , i t s s o l u b i l i t y i n t h e rumen f l u i d ( S m i t h , 1975; Tamminga, 1 9 8 0 ) , i t s r a t e o f p a s s a g e , t h e l e v e l o f f e e d i n t a k e , t h e n a t u r e o f t h e d i e t a n d rumen pH (Tamminga, 1 9 8 0 ) . V a l u e s o f 100% f o r g r a s s p r o t e i n , 90% f o r c a s e i n , 6 0 - 8 3 % f o r w h e a t e n h a y , a n d 40% f o r t h e r e l a t i v e l y i n s o l u b l e m a i z e p r o t e i n , z e i n , h a v e b e e n r e p o r t e d ( B r o o m e , 1 9 6 8 ) . P r o t e i n e n t e r i n g t h e rumen i s c a t a b o l i z e d by p r o t e o l y t i c b a c t e r i a t o p e p t i d e s a n d a m i n o a c i d s ( A l l i s o n , 1 9 7 0 ) . A m i n o a c i d s i n t u r n a r e d e a m i n a t e d t o g i v e a s e r i e s o f s t r a i g h t a n d b r a n c h e d - c h a i n V F A s , ammonia a n d c a r b o n d i o x i d e ( A n n i s o n a n d L e w i s , 1959; Kay a n d H o b s o n , 1963; H u n g a t e , 1 9 6 6 ) . N o n - p r o t e i n n i t r o g e n o f d i e t a r y o r i g i n o r f r o m u r e a w h i c h i s r e c y c l e d i n s a l i v a o r w h i c h d i f f u s e s f r o m t h e b l o o d a c r o s s t h e rumen w a l l (Rook a n d Thomas, 1969) i s b r o k e n down w i t h i n t h e rumen t o ammonia. U r e a i s h y d r o l y z e d by m i c r o b i a l u r e a s e t o ammonia ( B o d a e_t a l . , 1976) a n d c a r b o n d i o x i d e ( H u h t a n e n a n d G a l l , 1 9 5 5 ) . N i t r a t e i s r e d u c e d t o n i t r i t e a n d e v e n t u a l l y t o 10 ammonia i n t h e rumen ( A l l i s o n , 1 9 7 0 ) . Th e rumen b a c t e r i a may u s e p e p t i d e s , a m i n o a c i d s , ammonia, t h e n i t r o g e n o u s c ompounds r e l e a s e d by t h e a u t o l y s i s o f m i c r o o r g a n i s m s , o r c o m b i n a t i o n s o f t h e s e a s s o u r c e s o f n i t r o g e n t o c o n v e r t t o m i c r o b i a l p r o t e i n ( A n n i s o n a n d L e w i s , 1959; H o b s o n , 1 9 7 1 ) . Amino a c i d s c a n be d i r e c t l y a s s i m i l a t e d by some rumen b a c t e r i a a n d i n c e r t a i n o f t h e s e s p e c i e s ( s u c h a s B a c t e r o i d e s r u m i n i c o l a ) t h e a m i n o a c i d s a r e e s s e n t i a l f o r g r o w t h ( H u n g a t e , 1 9 6 6 ) . N e v e r t h e l e s s , e v e n i n a n i m a l s f e d r a t i o n s c o n t a i n i n g a p p r e c i a b l e q u a n t i t i e s o f p r o t e i n , a l a r g e p o r t i o n o f t h e a m i n o a c i d s i n m i c r o b i a l p r o t e i n s i s s y n t h e s i z e d de n o v o f r o m i n t e r m e d i a t e s o r e n d - p r o d u c t s o f c a r b o h y d r a t e f e r m e n t a t i o n , o r e n d - p r o d u c t s o f a m i n o a c i d m e t a b o l i s m ( A l l i s o n , 1 9 7 0 ) . T h e r e i s g o o d e v i d e n c e t h a t ammonia i s t h e p r e f e r r e d s o u r c e o f n i t r o g e n f o r m o s t rumen b a c t e r i a a n d i s e s s e n t i a l f o r t h e g r o w t h o f s e v e r a l i m p o r t a n t s p e c i e s ( B r y a n t a n d R o b i n s o n , 1962; 1 9 6 3 ) . F i g u r e 3 i n d i c a t e s t h e f l o w o f n i t r o g e n i n t h e rumen. P r o t e i n a n d c a r b o h y d r a t e f e r m e n t a t i o n w i t h i n t h e rumen a r e h i g h l y i n t e r d e p e n d e n t . T h e c o n v e r s i o n o f ammonia t o p r o t e i n r e q u i r e s e n e r g y . T h e r e f o r e , t h e amount o f 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 d e p e n d s on t h e amount o f e n e r g y s u p p l i e d by t h e d i e t ( B r o o m e , 1 9 6 8 ) . Ammonia i s a b s o r b e d f r o m t h e rumen a n d c o n v e r t e d t o u r e a i n t h e l i v e r , w h i c h may be e x c r e t e d i n t h e u r i n e o r be r e c y c l e d t o t h e rumen v i a t h e s a l i v a o r by d i f f u s i o n a c r o s s t h e rumen w a l l (Rook a n d Thomas, 1 9 6 9 ) . When t h e s u p p l y o f ammonia e x c e e d s t h e c a p a c i t y o f t h e m i c r o o r g a n i s m s t o u t i l i z e i t , t h i s c a n l e a d t o i n e f f i c i e n t p r o t e i n u t i l i z a t i o n d u e t o t h e 11 .> PROTEIN ..peptides, amides f etc. amino acids NON-PROTEIN NITROGEN <r NO-NO 2 carbon skeletons microbial protein glucose Blood Urea t l i v e r — > U r e a t ^Portal Blood NH 3 Figure 3. The flow of nitrogen in the rumen, absorption of ammonia from the rumen and i t s net loss as urea in the urine, representing a loss of nitrogen by the ruminant. The inclusion of starch in the ration permits the maintenance of a bigger microbial population capable of greater ammonia u t i l i z a t i o n which results in less wastage of dietary protein. Digestion of material flowing into the duodenum, including microbial c e l l s and dietary proteins which escape ruminal digestion, provides the animal with the e s s e n t i a l amino acids (Smith, 1 9 7 5 ) . It i s important to consider the e f f i c i e n c y of microbial degradation of dietary protein to assess the value to the ruminant of the interaction of microbes with dietary protein. A discussion of the e f f i c i e n c y of microbial degradation of dietary 1 2 p r o t e i n must t a k e i n t o c o n s i d e r a t i o n how much p r o t e i n e s c a p e s d e g r a d a t i o n , how much o f d e g r a d e d p r o t e i n i s r e f o r m e d i n t o m i c r o b i a l c e l l s , a n d what a r e t h e v a l u e s t o t h e h o s t o f t h e s e n i t r o g e n s o u r c e s on r e a c h i n g t h e s m a l l i n t e s t i n e . D e p e n d i n g on t h e f e e d s t u f f t h e r e i s c o n s i d e r a b l e v a r i a t i o n i n t h e amount o f p r o t e i n w h i c h b y - p a s s e s t h e r u m e n o r e t i c u l u m u n a l t e r e d by t h e m i c r o b e s . H a g e m e i s t e r e t §_1. ( 1 9 7 6 ) r e p o r t e d f i n d i n g s t h a t a n y w h e r e f r o m 23-67 g o f n o n - b a c t e r i a l n i t r o g e n p a s s e d t o t h e i n t e s t i n e u n a l t e r e d f o r e a c h 100 g o f d i e t a r y n i t r o g e n . T h e s e w o r k e r s e m p l o y e d a r a n g e o f n i t r o g e n s o u r c e s i n c l u d i n g f o r a g e s , m i x e d r a t i o n s a n d / o r u r e a a n d f e d them t o d a i r y cows f i t t e d w i t h rumen a n d d u o d e n a l r e - e n t r a n t c a n n u l a e . V a l u e s f o r b y - p a s s e d p r o t e i n , o f 23-67 g mean t h a t o n l y 3 3 - 7 7 % o f t h e d i e t a r y n i t r o g e n i s a t t a c k e d by rumen m i c r o o r g a n i s m s a n d c o n s i d e r i n g t h a t a p o r t i o n o f t h e p r o t e i n a t t a c k e d by m i c r o o r g a n i s m s i s l o s t a s ammonia, t h e amount o f d i e t a r y n i t r o g e n c o n v e r t e d t o m i c r o b i a l n i t r o g e n w o u l d be s m a l l e r s t i l l . S m i t h ( 1 9 6 9 ) r e p o r t e d t h a t w i t h m o s t n o r m a l d i e t s o f h a y a n d / o r c o n c e n t r a t e s , i n w h i c h ammonia a c c u m m u l a t i o n i s n o t q u a n t i t a t i v e l y i m p o r t a n t , a b o u t 5 0 - 8 0 % o f t h e f e e d n i t r o g e n i s c o n v e r t e d t o m i c r o b i a l n i t r o g e n o u s c o m p o u n d s by t h e t i m e t h e d i g e s t a e n t e r t h e s m a l l i n t e s t i n e . A c c o r d i n g t o B u r r o u g h s e t a l . ( 1 9 7 5 ) , d e p e n d i n g on t h e e n e r g y / p r o t e i n r a t i o s a n d s o l u b i l i t y c h a r a c t e r i s t i c s o f t h e d i e t s , v a l u e s f o r b y - p a s s e d p r o t e i n s r a n g e d f r o m 0-50% w h i l e p e r c e n t a g e r e f o r m e d p r o t e i n s r a n g e d f r o m 10-100% o f t h a t p r o t e i n d e g r a d e d by rumen m i c r o o r g a n i s m s . K a u f m a n n ( 1 9 8 0 ) r e p o r t e d t h a t when t h e d i e t 1 3 c o n t a i n e d 13% c r u d e p r o t e i n a n d 5 5 0 - 6 0 0 g s t a r c h e q u i v a l e n t / k g d r y m a t t e r , t h e r e was l i t t l e n e t c h a n g e i n t h e amount o f p r o t e i n d u r i n g p a s s a g e t h r o u g h t h e rumen, i n d i c a t i n g t h a t p r o t e i n d e g r a d a t i o n was a p p r o x i m a t e l y e q u a l t o 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 a n d t h a t t h e n i t r o g e n r e q u i r e m e n t f o r e f f i c i e n t m i c r o b i a l s y n t h e s i s i s met a t t h i s l e v e l o f d i e t a r y c r u d e p r o t e i n %. T h e d i g e s t i b i l i t y o f m i c r o b i a l p r o t e i n r e a c h i n g t h e s m a l l i n t e s t i n e w i l l d e p e n d on t h e p r o p o r t i o n s o f b a c t e r i a a n d p r o t o z o a . F e e d i n g m i c r o b i a l p r e p a r a t i o n s t o r a t s r e s u l t e d i n a v e r a g e t r u e d i g e s t i b i l i t i e s o f 66 a n d 88% f o r rumen b a c t e r i a a n d p r o t o z o a , r e s p e c t i v e l y ( B u r r o u g h s e t a l . , 1975; C h a l u p a , 1 9 7 5 ) . T h e d i g e s t i b i l i t y o f p r o t e i n w h i c h e s c a p e s m i c r o b i a l d e g r a d a t i o n , u pon r e a c h i n g t h e s m a l l i n t e s t i n e , i s s i m i l a r t o i t s d i g e s t i b i l i t y i n a m o n o g a s t r i c . A c c o r d i n g t o S m i t h ( 1 9 6 9 ) l i t t l e more t h a n 6 0 - 7 0 % o f t h e m i c r o b i a l n i t r o g e n c o m p o u n d s e n t e r i n g t h e duodenum i s d i g e s t e d i n t h e s m a l l i n t e s t i n e , w i t h a n o t h e r 10-20% w a s t e f u l l y f e r m e n t e d i n t h e l a r g e i n t e s t i n e . A b o u t 12-18% o f t h e n i t r o g e n a b s o r b e d f r o m t h e s m a l l i n t e s t i n e i s i n t h e f o r m o f n u c l e i c a c i d p r o d u c t s o f l i t t l e o r no n u t r i t i o n a l v a l u e ( S m i t h , 1 9 7 5 ) . S m i t h ( 1 9 6 9 ) e x p l a i n s t h a t a p p r o x i m a t e l y 4 0 - 5 0 % o f t h e m i c r o b i a l n u c l e i c a c i d n i t r o g e n p r o d u c e d i n t h e rumen i s n o t a b s o r b e d f r o m t h e g u t o r i s a b s o r b e d b u t i s e x c r e t e d i n t h e u r i n e a s a l l a n t o i n a n d t h a t m ost o f t h e r e m a i n d e r e n t e r s t h e u r e a p o o l . I t a p p e a r s , t h e r e f o r e , t o be o f l i m i t e d v a l u e t o t h e a n i m a l . 14 3. L i p i d s P o t e n t i a l s o u r c e s o f d i e t a r y l i p i d s f o r d o m e s t i c r u m i n a n t s may be o f v e g e t a b l e , a n i m a l o r m i c r o b i a l o r i g i n . V e g e t a b l e s o u r c e s i n c l u d e p l a n t l e a v e s , s t e m s , r o o t s , f r u i t c o a t s a n d s e e d s ( H i l d i t c h a n d W i l l i a m s , 1964) a n d may c o n v e n i e n t l y be c a t e g o r i z e d a s : p a s t u r e l e g u m e s a n d g r a s s e s i n w h i c h t h e 4-6% t o t a l l i p i d s ( m o s t l y i n t h e f o r m o f mono- a n d d i - g a l a c t o s y l d e r i v a t i v e s o f 1 , 2 - d i g l y c e r i d e s ) c o n t a i n a h i g h p r o p o r t i o n o f l i n o l e n i c a c i d ( H i l d i t c h a n d W i l l i a m s , 1 9 6 4 ) ; a n d c o n c e n t r a t e s ( s o y b e a n m e a l , l i n s e e d m e a l , b a r l e y , o a t s , e t c . ) i n w h i c h t h e 2-10% t o t a l l i p i d ( c o n s i s t i n g l a r g e l y o f t r i g l y c e r i d e s ) i s c h a r a c t e r i z e d by a h i g h c o n t e n t o f C18 u n s a t u r a t e d a c i d s , p r e d o m i n a n t l y l i n o l e i c a c i d ( H i l d i t c h a n d W i l l i a m s , 1 9 6 4 ) . A n i m a l l i p i d s , p r e s e n t o n l y i n d o m e s t i c r u m i n a n t d i e t s , a r e i n c l u d e d e i t h e r t o m o d i f y t h e p h y s i c a l p r o p e r t i e s o f t h e r a t i o n o r t o i n c r e a s e r a t i o n e n e r g y d e n s i t y . D i e t a r y m i c r o b i a l l i p i d s a r e a v a i l a b l e t o r u m i n a n t s f e d f e r m e n t a t i o n b y - p r o d u c t s ( e . g . B r e w e r ' s g r a i n s ) , o r e n s i l e d f e e d s , a n d s i n c e rumen m i c r o o r g a n i s m s a r e c a p a b l e o f de n o v o s y n t h e s i s o f l i p i d s , t h e s e m i c r o b i a l l i p i d s become a v a i l a b l e i n t h e abomasum o f r u m i n a n t s on a n y d i e t ( H a r f o o t , 1 9 7 8 ) . I n summary, d i e t a r y l i p i d s o f d o m e s t i c r u m i n a n t s may i n c l u d e : g a l a c t o s y l d i g l y c e r i d e s , t r i g l y c e r i d e s , w a x e s , p h o s p h o l i p i d s , s u l p h o l i p i d s , s t e r o l s , s t e r o l e s t e r s , h y d r o c a r b o n s a n d f r e e f a t t y a c i d s ( F F A s ) ( H i l d i t c h a n d W i l l i a m s , 1964; G a r t o n , 1965; Rook a n d Thomas, 1969; Dawson a n d Kemp, 1 9 7 0 ) . 15 R u m i n a n t d e p o t f a t c o m p o s i t i o n i s l i t t l e a f f e c t e d by t h e l i p i d s p r e s e n t i n t h e d i e t . T h e f r e e f a t t y a c i d s p a l m i t i c , o l e i c a n d s t e a r i c a c c o u n t f o r a p p r o x i m a t e l y 9 0 % o f t h e t o t a l f a t t y a c i d s i n r u m i n a n t d e p o t f a t s ( H i l d i t c h a n d W i l l i a m s , 1 9 6 4 ) . T h e s e d e p o t f a t s c o n t a i n s u b s t a n t i a l a m o u n t s o f t r a n s -i s o m e r s a s w e l l a s q u a n t i t i e s o f b r a n c h e d - c h a i n a c i d s , a n d m i l k f a t p a r t i c u l a r l y c o n t a i n s a p p r e c i a b l e q u a n t i t i e s o f o d d - l e n g t h a c i d s a s w e l l ( C h u r c h , 1 9 7 0 ) . T h e t r a n s , o d d - l e n g t h a n d b r a n c h e d - c h a i n a c i d s a r e n o t c h a r a c t e r i s t i c o f p l a n t l i p i d s . S y n t h e s i s o f t h e s e a c i d s must t h e r e f o r e t a k e p l a c e i n t h e rumen, t h e l o w e r g a s t r o i n t e s t i n a l t r a c t , o r t h e b o d y t i s s u e s ( C h u r c h , 1 9 7 0 ) . R e s e a r c h h a s shown t h a t t h e p e c u l i a r f e a t u r e s o f r u m i n a n t l i p i d s c a n be r e l a t e d t o t h e e f f e c t s o f rumen m i c r o o r g a n i s m s on d i e t a r y l i p i d s ( G a r t o n , 1 9 6 7 ) . M i c r o b i a l f e r m e n t a t i o n i n t h e rumen p r o f o u n d l y m o d i f i e s t h e d i e t a r y l i p i d s . T he m a j o r e v e n t s o f l i p i d m e t a b o l i s m i n t h e rumen i n c l u d e : 1. h y d r o l y s i s 2. b i o h y d r o g e n a t i o n o f u n s a t u r a t e d f a t t y a c i d s 3. l i p i d b i o s y n t h e s i s 4. f e r m e n t a t i o n o f g l y c e r o l a n d g a l a c t o s e 16 a . H y d r o l y s i s D i e t a r y l i p i d s a r e h y d r o l y z e d by rumen m i c r o o r g a n i s m s ( G a r t o n , 1967; A n n i s o n , 1972) w i t h t h e r e l e a s e o f f a t t y a c i d s a n d g l y c e r o l f r o m e s t e r c o m b i n a t i o n ( G a r t o n , 1967; Rook a n d Thomas, 1969; S c o t t a n d C o o k , 1 9 7 5 ) , a n d i n t h e c a s e o f g a l a c t o g l y c e r i d e s o f l e a f l i p i d s , g a l a c t o s e a l s o ( B a i l e y , 1962; G a r t o n , 1 9 6 5 ) . P h o s p h o l i p i d s t o o , c a n be h y d r o l y z e d by rumen m i c r o o r g a n i s m s (Dawson, 1959; G a r t o n , 1 9 6 1 ) . H y d r o l y s i s o f t r i g l y c e r i d e s a n d o t h e r d i e t a r y l i p i d s i s b r o u g h t a b o u t u n d e r t h e a c t i o n o f m i c r o b i a l l i p a s e s ( L e a t a n d H a r r i s o n , 1 9 7 5 ) . I t seems t h e e x t e n t t o w h i c h t r i g l y c e r i d e s a r e h y d r o l y z e d i n rumen c o n t e n t s may be r e l a t e d t o t h e d e g r e e o f u n s a t u r a t i o n o f t h e i r c o m p o n e n t a c i d s , t h a t i s , t h e g r e a t e r t h e d e g r e e o f u n s a t u r a t i o n , t h e g r e a t e r i s t h e e x t e n t o f h y d r o l y s i s ( G a r t o n et_ a l . , 1 9 5 9 ) . I t was shown by G a r t o n ( 1 9 6 5 ) t h a t m i x e d m i c r o o r g a n i s m s o f t h e s h e e p rumen p o s s e s s b o t h c- a n d p-g a l a c t o s i d a s e a c t i v i t y . T h e g a l a c t o s e o f l e a f g a l a c t o l i p i d s i s l i b e r a t e d by t h e a c t i o n o f t h e s e two e n z y m e s ( G a r t o n , 1 9 6 4 ) . 17 b. B i o h y d r o q e n a t i o n o f U n s a t u r a t e d F a t t y A c i d s C18 p o l y e n o i c a c i d s r e s u l t i n g f r o m h y d r o l y s i s o f d i e t a r y l i p i d s a r e p r o g r e s s i v e l y b i o h y d r o g e n a t e d by rumen m i c r o o r g a n i s m s t o more s a t u r a t e d c o m p o n e n t s b e f o r e p a s s a g e t o t h e i n t e s t i n e ( G a r t o n e t a l . , 1958, 1959; G a r t o n , 1967; A r m s t r o n g , 1968; Rook a n d Thomas, 1969; Dawson a n d Kemp, 1970; H o b s o n , 1971; L e a t a n d H a r r i s o n , 1975; S c o t t a n d C o o k , 1 9 7 5 ) . T h i s f i n d i n g was f i r s t r e p o r t e d by R e i s e r a n d K u i k e n ( 1 9 5 1 ) . I t was d e m o n s t r a t e d by J o h n s ( 1 9 5 5 ) t h a t s t e a r i c a c i d c o u l d a r i s e f r o m t h e h y d r o g e n a t i o n o f d i e t a r y l i n o l e n i c a c i d p r e s e n t a s g l y c e r i d e o r a s f r e e f a t t y a c i d i n t h e rumen. G a r t o n ( 1 9 6 7 ) s u p p o r t e d t h i s f i n d i n g a n d o b s e r v e d t h a t u n s a t u r a t e d f a t t y a c i d s c o u l d u n d e r g o r e d u c t i o n w h i l e s t i l l i n g l y c e r i d e c o m b i n a t i o n , a l t h o u g h a p p a r e n t l y more r e a d i l y f o l l o w i n g t h e i r h y d r o l y t i c r e l e a s e . L a t e r work r e p o r t s t h a t i t i s n e c e s s a r y f o r e s t e r s o f u n s a t u r a t e d f a t t y a c i d s t o be h y d r o l y z e d b e f o r e t h e i r u n s a t u r a t e d f a t t y a c i d m o i e t i e s c a n be h y d r o g e n a t e d ( K e e n e y , 1970; N o b l e , 1 9 7 8 ) . T h e r e i s some e v i d e n c e t h a t t h e more u n s a t u r a t e d f a t t y a c i d s a r e p r e f e r e n t i a l l y h y d r o g e n a t e d o v e r f a t t y a c i d s w i t h f e w e r d o u b l e b o n d s ( G a r t o n , 1 9 6 1 ) . Rumen m i c r o b i a l h y d r o g e n a t i o n o f t h e u n s a t u r a t e d f a t t y a c i d s w h i c h p r e d o m i n a t e i n p l a n t l i p i d s r e s u l t s i n t h e f o r m a t i o n o f p o s i t i o n a l a n d g e o m e t r i c a l i s o m e r s o f o c t a t r i e n o i c , - d i e n o i c a n d - m o n o e n o i c f a t t y a c i d s a s w e l l a s o c t a d e c a n o i c a c i d ( S h o r l a n d e t a l . , 1957; G a r t o n , 1961, 1967; A r m s t r o n g , 1968; Rook a n d Thomas, 1969; K e e n e y , 1970; L o u g h , 1970; L e a t a n d H a r r i s o n , 1975; S c o t t a n d C o o k , 1 9 7 5 ) . 18 P o s i t i o n a l i s o m e r s r e s u l t f r o m t h e m i g r a t i o n o f d o u b l e b o n d s d u r i n g f e r m e n t a t i o n o f u n s a t u r a t e d f a t t y a c i d s ( G a r t o n , 1 9 6 7 ) . r - l i n o l e n i c a c i d , a p o s i t i o n a l i s o m e r o f l i n o l e n i c a c i d , i s shown i n F i g u r e 4. C H 3 ( C H 2 ) a C H = C H C H 2 C H = C H C H 2 C H = C H ( C H 2 ) , C O O H r - l i n o l e n i c [ c i s - 6 , 9 , 1 2 - o c t a d e c a t r i e n o i c ] C H 3 C H 2 C H = C H C H 2 C H = C H C H 2 C H = C H ( C H 2 ) 7 C O O H L i n o l e n i c [ c i s - 9 ,12,1.5-oc t a d e c a t r i e n o i c ] F i g u r e 4. U n s a t u r a t e d f a t t y a c i d s : p o s i t i o n a l i s o m e r s D u r i n g h y d r o g e n a t i o n o f u n s a t u r a t e d f a t t y a c i d s , some o f t h e n a t u r a l l y o c c u r r i n g c i s f o r m s o f t h e s e a c i d s a r e c o n v e r t e d i n t o t r a n s i s o m e r s . One e x a m p l e i s e l a i d i c a c i d w h i c h i s a t r a n s i s o m e r o f o l e i c a c i d f o r m e d d u r i n g b i o h y d r o g e n a t i o n o f l i n o l e i c a c i d by B u t y r i v i b r i o f i b r i s o l v e n s ( K e p l e r e t a l . , 1 9 6 6 ) . T h e s t r u c t u r e s o f e l a i d i c a c i d ( t r a n s - 9 - o c t a d e c e n o i c a c i d ) a n d o l e i c a c i d ( c i s - 9 - o c t a d e c e n o i c a c i d ) a r e shown i n F i g u r e 5. 19 C H 3 ( C H 2 ) 7 C H = C H ( C H 2 ) 7 C O O H C H 3 ( C H 2 ) 7 C H I H C ( C H 2 ) 7 C O O H E l a i d i c [ t r a n s - 9 - o c t a d e c e n o i c ] C H 3 ( C H 2 ) 7 C H = C H ( C H 2 ) 7 C O O H H C ( C H 2 ) 7 C O O H H C ( C H 2 ) 7 C O O H O l e i c [ c i s - 9 - o c t a d e c e n o i c ] F i g u r e 5. U n s a t u r a t e d f a t t y a c i d s : c i s a n d t r a n s i s o m e r s , c . L i p i d B i o s y n t h e s i s B r a n c h e d - c h a i n a c i d s a n d f a t t y a c i d s h a v i n g a n o d d number o f c a r b o n a t o m s h a v e b e e n d e t e c t e d i n r u m i n a n t m i l k , b o d y a n d b l o o d s e r u m , l i p i d s ( G a r t o n , 1967; H o b s o n , 1 9 7 1 ) . T h e m a j o r s o u r c e o f t h e s e l i p i d s i s t h e rumen m i c r o o r g a n i s m s ( G a r t o n , 1961, 1965, 1967; K e e n e y , 1970; S c o t t a n d C o o k , 1 9 7 5 ) , w h i c h a r e c a p a b l e o f l i p i d b i o s y n t h e s i s de n o v o u s i n g V F A s f r o m c a r b o h y d r a t e a n d a m i n o a c i d m e t a b o l i s m ( H a r f o o t , 1 9 7 8 ) . G e n e r a l l y , t h e b r a n c h e d - c h a i n f a t t y a c i d s f o u n d i n r u m i n a n t l i p i d s h a v e one m e t h y l b r a n c h i n t h e m o l e c u l e a n d a r e d e s i g n a t e d a s b e l o n g i n g e i t h e r t o t h e i s o o r a n t e i s o s e r i e s a s shown i n F i g u r e 6. 20 M i c r o b i a l l i p i d s s y n t h e s i z e d i n t h e rumen h a v e b e e n shown C H 3 C H 3 I I C H 3 C H ( C H 2 ) n C O O H C H 3 C H 2 C H ( C H 2 ) n C O O H i s o a c i d a n t e i s o a c i d F i g u r e 6. E x a m p l e s o f b r a n c h e d - c h a i n f a t t y a c i d s f o u n d i n r u m i n a n t l i p i d s , w h i c h a r e o f m i c r o b i a l o r i g i n . t o c o n t a i n l o n g c h a i n f a t t y a c i d s , some w i t h a n o d d number o f c a r b o n a t o m s ( C 1 3 , C15, C17) a n d b r a n c h e d - c h a i n i s o m e r s o f t h e s e a n d o f f a t t y a c i d s c o n t a i n i n g a n e v e n number o f c a r b o n a t o m s ( A r m s t r o n g , 1 9 6 8 ) . S t r a i g h t - a n d b r a n c h e d - c h a i n C15 a c i d s a r e e f f i c i e n t l y b i o s y n t h e s i z e d i n t h e rumen p a r t i c u l a r l y f r o m a m i n o a c i d c a t a b o l i c p r o c e s s e s ( V i v i a n i , 1 9 7 0 ) . Some s t r a i n s o f B a c t e r o i d e s r u m i n i c o l a a n d P e p t o s t r e p t o c o c c u s e l s d e n i i p r o d u c e d b r a n c h e d - c h a i n 4 a n d 5 - c a r b o n a c i d s f r o m b r a n c h e d - c h a i n a m i n o a c i d s ( A l l i s o n , 1 9 7 0 ) . I s o v a l e r i c a c i d , 2 - m e t h y l b u t y r i c a c i d a n d i s o b u t y r i c a c i d w e r e p r o d u c e d f r o m l e u c i n e , i s o l e u c i n e a n d v a l i n e , r e s p e c t i v e l y . I n c e r t a i n s t r a i n s o f rumen b a c t e r i a a n d p r o t o z o a , b r a n c h e d - c h a i n f a t t y a c i d s s e r v e a s a c a r b o n s o u r c e f o r t h e s y n t h e s i s o f b r a n c h e d - c h a i n , o d d - n u m b e r e d , h i g h e r f a t t y a c i d s a n d a l d e h y d e s ( A l l i s o n e t a l . , 1 9 6 2 ) . T h e c o n t r i b u t i o n by m i c r o b i a l f a t t y a c i d s t o t h e f l o w o f f a t t y a c i d s e n t e r i n g t h e 21 s m a l l i n t e s t i n e may a l m o s t e q u a l t h e d i e t a r y i n t a k e o f f a t t y a c i d s on a l o w r o u g h a g e r a t i o n ( S u t t o n e t a l . , 1 9 7 0 ) . d . F e r m e n t a t i o n o f G l y c e r o l a n d G a l a c t o s e B o t h g l y c e r o l a n d g a l a c t o s e r e l e a s e d f r o m l i p i d s i n t h e rumen a r e f e r m e n t e d t o y i e l d V F A s ( G a r t o n , 1 9 6 7 ) . H o b s o n a n d Mann ( 1 9 6 1 ) d e m o n s t r a t e d t h a t g l y c e r o l i s f e r m e n t e d m a i n l y t o p r o p i o n i c a c i d a n d t h a t g a l a c t o s e c a n be f e r m e n t e d t o a c e t i c , p r o p i o n i c a n d b u t y r i c a c i d s . B. U n p r o t e c t e d L i p i d s A l t h o u g h "the l i t e r a t u r e i s b y no means c o n c l u s i v e , t h e r e i s s u f f i c i e n t e v i d e n c e t o i n d i c a t e t h a t u n d e r c e r t a i n c i r c u m s t a n c e s , f e e d i n g f r e e o r u n p r o t e c t e d l i p i d s t o r u m i n a n t s r e s u l t s i n d e l e t e r i o u s e f f e c t s on a n i m a l p r o d u c t i v i t y i n o n e f o r m o r a n o t h e r . T h e maximum l e v e l o f f r e e f a t w h i c h may be a d d e d t o a r u m i n a n t r a t i o n h a s b e e n recommended by w o r k e r s t o be 3-8% ( A r m s t r o n g a n d B e e v e r , 1969; C u i t u n e t a l . , 1975; P a l m q u i s t a n d J e n k i n s , 1 9 8 0 ) . Th e a d v e r s e e f f e c t s o f f e e d i n g f r e e o i l s o r f a t s t o r u m i n a n t s h a v e i n c l u d e d : d e c r e a s e d v o l u n t a r y f e e d i n t a k e ( P e r r y e t a l . , 1 976; K o w a l c z y k e t a _ l . , 1 9 7 7 ) , a n d d e c r e a s e d d i g e s t i b i l i t i e s o f d r y m a t t e r , f i b r e a n d c a l c i u m ( G r a i n g e r e t a l . , 1961; M a c l e o d a n d B u c h a n a n - S m i t h , 1972; P e r r y e t a l . , 1 976; K o w a l c z y k et_ a l . , 1 9 7 7 ) . F u r t h e r , r e s e a r c h e r s h a v e r e p o r t e d t h a t f e e d i n g f r e e l i p i d s c a u s e d d e c r e a s e s i n m i l k f a t % a n d y i e l d (Brumby et_ a _ l . , 1972; M a c l e o d a n d Wood, 1972; R i n d s i g 22 a n d S h u l t z , 1974; S e i n e r a n d S h u l t z , 1980; S t o r r y e t a l . , 1 9 8 0 ) , a n d d e c r e a s e s i n m i l k s o l i d s - n o t - f a t % (SNF %) (Wrenn e t a l . , 1 9 7 8 ) . F r e e l i p i d s h a v e c a u s e d d e c r e a s e s i n t h e a c e t a t e t o p r o p i o n a t e r a t i o i n t h e rumen a s a r e s u l t o f i n c r e a s e d p r o p i o n a t e l e v e l s c o u p l e d w i t h d e c r e a s e d a c e t a t e l e v e l s (Brumby e t a l . , 1972; S t o r r y e t a l . , 1974a; S e i n e r a n d S h u l t z , 1 9 8 0 ) . C. P r o t e c t e d l i p i d s 1. T e c h n o l o g y I n v i e w o f t h e f a c t t h a t rumen m i c r o o r g a n i s m s h a v e a p r o f o u n d i n f l u e n c e on d i e t a r y l i p i d s a n d p r o t e i n s , t h u s r e d u c i n g t h e i r a v a i l a b i l i t i e s t o t h e r u m i n a n t h o s t , v a r i o u s p r o c e d u r e s h a v e b e e n i n v e s t i g a t e d t o a t t e m p t t o c i r c u m v e n t t h i s p r o b l e m . R e s e a r c h e r s a t t h e C o mmonwealth S c i e n t i f i c a n d I n d u s t r i a l R e s e a r c h O r g a n i z a t i o n ( C S I R O ) e x p e r i m e n t e d w i t h t h e p r o t e c t i o n o f p r o t e i n u s i n g a l d e h y d e s . T h e y f o u n d a c e t a l d e h y d e , g l u t a r a l d e h y d e , g l y o x a l a n d f o r m a l d e h y d e t o be e f f e c t i v e a n d s e l e c t e d t h e l a t t e r f o r r e a s o n s o f c o s t a n d s u p p l y ( F e r g u s o n , 1975) . T h e p r o t e c t i o n o f p r o t e i n t r e a t e d w i t h f o r m a l d e h y d e r e s u l t s f r o m c r o s s l i n k a g e s f o r m e d b e t w e e n t h e p r o t e i n a n d t h e f o r m a l d e h y d e , w h i c h a r e r e s i s t a n t t o m i c r o b i a l a t t a c k . A t n e u t r a l pH a n d room t e m p e r a t u r e , t h e p r i n c i p a l r e a c t i o n a p p e a r s t o be t h e f o r m a t i o n o f m e t h y l o l g r o u p s on t h e t e r m i n a l a - a m i n o g r o u p s o f p r o t e i n c h a i n s a n d t h e c - a m i n o g r o u p s o f l y s i n e , f o l l o w e d b y t h e c o n d e n s a t i o n o f t h e s e g r o u p s w i t h t h e p r i m a r y 23 a m i d e g r o u p s o f a s p a r a g i n e a n d g l u t a m i n e , a n d t h e g u a n i d y l g r o u p o f a r g i n i n e t o f o r m i n t e r m o l e c u l a r a n d i n t r a m o l e c u l a r m e t h y l e n e b r i d g e s . T h e r e a c t i o n i s r e v e r s e d u n d e r a c i d i c c o n d i t i o n s w i t h t h e l i b e r a t i o n o f f o r m a l d e h y d e ( F r a n k e l - C o n r a t a n d O l c o t t , 1 9 4 8 ) . T h e d e v e l o p m e n t o f p r o t e i n p r o t e c t i o n p r o c e d u r e s wa.s h i n d e r e d by t h e l a c k o f an a d e q u a t e m e t h o d f o r d e t e r m i n i n g t h e d e g r e e o f p r o t e c t i o n o f a p r o t e i n . T h i s p r o b l e m was o v e r c o m e when R e i s a n d S c h i n c k e l ( 1 9 6 3 ) d i s c o v e r e d t h a t w o o l g r o w t h was i n c r e a s e d w i t h a b o m a s a l i n f u s i o n s o f c a s e i n o r s u l p h u r -c o n t a i n i n g a m i n o a c i d s . T h i s f i n d i n g i n d i c a t e d a b i o l o g i c a l r e s p o n s e w h i c h c o u l d be u s e d t o e x a m i n e t h e e f f e c t i v e n e s s o f v a r i o u s t e c h n i q u e s f o r p r o t e i n p r o t e c t i o n . C o n s i d e r a b l e e x p e r i m e n t a t i o n was c o n d u c t e d t o d e t e r m i n e t h e o p t i m u m c o n d i t i o n s a n d q u a n t i t i e s o f f o r m a l d e h y d e t o u s e i n o r d e r t o p r o d u c e t h e maximum e f f e c t on w o o l g r o w t h . H e m s l e y e t a l . ( 1 9 7 3 ) c o n c l u d e d t h a t p r o t e i n ( i n t h i s c a s e c a s e i n ) p r o t e c t e d w i t h 1% b o u n d f o r m a l d e h y d e (1 g p e r 100 g p r o t e i n ) was an o p t i m a l l y p r o t e c t e d p r o t e i n o f i m p r o v e d n u t r i t i v e v a l u e f o r w o o l p r o d u c t i o n . A t t h i s l e v e l o f f o r m a l d e h y d e t h e d e g r a d a t i o n o f c a s e i n - n i t r o g e n t o a m m o n i a - n i t r o g e n by rumen m i c r o o r g a n i s m s i n v i t r o was r e d u c e d t o b e l o w 15%, a n d t h e n i t r o g e n d i g e s t i b i l i t y o f t h e c a s e i n i_n v i v o was m a i n t a i n e d a t o v e r 9 5 % o f t h a t o f u n p r o t e c t e d c a s e i n . T h e i n f o r m a t i o n o b t a i n e d f r o m r e s e a r c h on p r o t e c t e d p r o t e i n s was s u b s e q u e n t l y i n c o r p o r a t e d i n t o t h e p r o t e c t e d l i p i d p r o c e s s . S c o t t ejt a l . ( 1 9 7 0 ) d e v e l o p e d a p r o c e s s f o r p r o d u c i n g 24 ' p r o t e c t e d l i p i d s ' , w h i c h a r o s e f r o m t h e c o m b i n a t i o n o f two u n r e l a t e d t e c h n i q u e s : t h e p r o t e c t i o n o f p r o t e i n a n d t h e p r o d u c t i o n o f a s p r a y - d r i e d b u t t e r p o w d e r ( F o g e r t y a n d J o h n s o n , 1 9 8 0 ) . T h e o r i g i n a l p r o c e s s i n v o l v e d e m u l s i f i c a t i o n o f s a f f l o w e r o i l w i t h a c i d - p r e c i p i t a t e d c a s e i n , f o l l o w e d by h o m o g e n i z a t i o n . T h e s e i n i t i a l s t e p s p r o d u c e d m i c r o s c o p i c d r o p l e t s o f o i l c o a t e d w i t h p r o t e i n ( p a r t i c l e s 0.2-2.0 mm i n d i a m e t e r ) w h i c h were t h e n m i x e d w i t h f o r m a l d e h y d e a n d s p r a y -d r i e d ( S c o t t e t a l . , 1971; C.S.I.R.O., 1 9 7 4 ) . T h e f i n a l p r o d u c t was a d r y , f r e e - f l o w i n g p o w d e r c o n s i s t i n g o f m i n u t e o i l d r o p l e t s s u r r o u n d e d by a f o r m a l d e h y d e - p r o t e i n c o m p l e x . T h i s p r o t e c t e d l i p i d - p r o t e i n c o m p l e x was r e s i s t a n t t o m i c r o b i a l d e g r a d a t i o n i n t h e rumen ( F e r g u s o n et_ a _ l . , 1967) b e c a u s e t h e f o r m a l d e h y d e -p r o t e i n m e t h y l e n e b r i d g e s a n d o t h e r c r o s s - l i n k a g e s w e r e s u b s t a n t i a l l y i n s o l u b l e a t pH > 5 ( C . S . I . R . O . , 1974) a n d t h u s t h e c o n s t i t u e n t l i p i d s w e r e r e s i s t a n t t o m i c r o b i a l l i p o l y s i s a n d b i o h y d r o g e n a t i o n ( S c o t t et_ a l . , 1971; S c o t t a n d C o o k , 1 9 7 5 ) . T h e f o r m a l d e h y d e - t r e a t e d , p r o t e i n - l i p i d s u p p l e m e n t p a s s e d l a r g e l y u n d i g e s t e d f r o m t h e rumen t o t h e abomasum w h e r e t h e a c i d i c c o n d i t i o n s (pH < 4) r e n d e r e d t h e p r o t e i n - f o r m a l d e h y d e c r o s s - l i n k a g e s u n s t a b l e a r i d b o t h t h e l i p i d a n d p r o t e i n w e r e r e l e a s e d a n d s u b s e q u e n t l y d i g e s t e d ( S c o t t a n d C o o k , 1 9 7 5 ) . S i n c e t h e o r i g i n a l d i s c o v e r y , t h e t e c h n o l o g y f o r p r o d u c t i o n o f p r o t e c t e d l i p i d s h a s i m p r o v e d a n d b r o a d e n e d . P r o t e c t e d l i p i d s h a v e b e e n p r o d u c e d , e i t h e r on a l a b o r a t o r y o r c o m m e r c i a l s c a l e , u s i n g c a s e i n , a l f a l f a , s k i m m i l k , c o l l a g e n , g e l a t i n , whey, b l o o d , b e a n p r o t e i n o r s e e d p r o t e i n a s t h e p r o t e i n 25 s o u r c e ( s ) a n d c o c o n u t , c o d - l i v e r , s a f f l o w e r , l i n s e e d , s u n f l o w e r , r a p e s e e d , c a n o l a , s o y b e a n , h y d r o g e n a t e d s o y b e a n o r s t e r c u l i a o i l s , c h o l e s t e r o l , t r i u n d e c a n o i n , o r t a l l o w a s t h e l i p i d s o u r c e ( s ) ( S t o r r y e t a l . , 1 9 8 0 ) . P r e s e n t t e c h n o l o g y w o u l d make p o s s i b l e t h e p r o t e c t i o n o f v i r t u a l l y a n y s u f f i c i e n t l y s o l u b l e p r o t e i n a n d a n y l i p i d o r l i p i d - s o l u b l e c o m p o u n d . I t w o u l d be p o s s i b l e , t h e r e f o r e , t o b y -p a s s t h e rumen w i t h f a t s o l u b l e s u b s t a n c e s s u c h a s h o r m o n e s a n d f l a v o u r i n g a g e n t s w h i c h a r e n o r m a l l y d e g r a d e d i n t h e rumen ( H a a s e , 1 9 7 7 ) . T h e p r a c t i c a l a p p l i c a t i o n o f p r o t e c t e d l i p i d t e c h n o l o g y c a n be d i v i d e d i n t o two d i s t i n c t a r e a s , e a c h h a v i n g i t s own p a r t i c u l a r e m p h a s i s a n d d e s i r e d g o a l s . R e s e a r c h a s a c o n s e q u e n c e , h a s b e e n l a r g e l y c o n c e n t r a t e d i n two r e g i o n s . C e r t a i n w o r k e r s h a v e i n v e s t i g a t e d p r o t e c t i n g a n d f e e d i n g p o l y u n s a t u r a t e d l i p i d s i n o r d e r t o i n c r e a s e t h e l e v e l s o f p o l y u n s a t u r a t e d f a t t y a c i d s i n t i s s u e s , d e p o t f a t s a n d m i l k s o f r u m i n a n t s , w i t h t h e v i e w i n m i n d t h a t t h e s e r u m i n a n t p r o d u c t s c o u l d b e n e f i t t h e c o n s u m e r a n d r e d u c e t h e r i s k o f c o r o n a r y h e a r t d i s e a s e . O t h e r r e s e a r c h e r s w e r e i n t e r e s t e d i n u s i n g p r o t e c t e d l i p i d s , s a t u r a t e d o r u n s a t u r a t e d , a s a means o f i n c r e a s i n g t h e e n e r g y i n t a k e o f r u m i n a n t s o r t h e i r e f f i c i e n c y o f p r o d u c t i o n . A l t h o u g h t h e m a j o r i t y o f p r o t e c t e d l i p i d s u p p l e m e n t s p r o d u c e d t o d a t e , c o n t a i n e d a m i x t u r e o f s a t u r a t e d a n d mono- o r p o l y u n s a t u r a t e d f a t t y a c i d s , t h e y a r e m o s t c o n v e n i e n t l y c l a s s i f i e d a n d e v a l u a t e d on t h e b a s i s o f t h e a p p l i c a t i o n f o r w h i c h t h e y w e r e u s e d . A p r o t e c t e d l i p i d , t h e r e f o r e , may be 26 c o n s i d e r e d a p o l y u n s a t u r a t e d p r o t e c t e d l i p i d o r a h i g h e n e r g y p r o t e c t e d l i p i d . 2. P o l y u n s a t u r a t e d P r o t e c t e d L i p i d s A p l e t h o r a o f i n f o r m a t i o n h a s b e e n p u b l i s h e d on t h e p o s s i b l e l i n k b e t w e e n t h e c o n s u m p t i o n o f s a t u r a t e d f a t a n d t h e i n c i d e n c e o f a t h e r o s c l e r o s i s , t h e p r i m a r y t y p e o f a r t e r i o s c l e r o s i s . B e t w e e n 1960 a n d 1980, r e c o m m e n d a t i o n s on m e a s u r e s t o p r e v e n t c o r o n a r y h e a r t d i s e a s e w e r e p u b l i s h e d by v a r i o u s b o d i e s a r o u n d t h e w o r l d i n c l u d i n g t h e n a t i o n a l h e a r t f o u n d a t i o n , o r t h e e q u i v a l e n t , i n C a n a d a , t h e U.S.A., B r i t a i n , A u s t r a l i a a n d New Z e a l a n d . One m a i n r e c o m m e n d a t i o n common t o a l l t h e s e r e p o r t s was a r e d u c t i o n i n t h e amount o f s a t u r a t e d f a t s c o n s u m e d . I n t h e A u s t r a l i a n r e p o r t ( A u s t r a l i a n Academy o f S c i e n c e , 1 9 7 5 ) , i t was recommended t h a t t h e r e be a n i n c r e a s e i n t h e i n t a k e s o f m o n o u n s a t u r a t e d a n d p o l y u n s a t u r a t e d f a t s r e l a t i v e t o s a t u r a t e d f a t s , s o a s t o p r o v i d e a p p r o x i m a t e l y e q u a l p r o p o r t i o n s o f c a l o r i e s f r o m t h e s e 3 t y p e s o f f a t s . A s was d i s c u s s e d e a r l i e r , t h e f a t t y a c i d c o m p o s i t i o n o f t h e f a t o f r u m i n a n t s i s r e m a r k a b l y c o n s t a n t a n d h a s a h i g h c o n t e n t o f s a t u r a t e d a n d m o n o u n s a t u r a t e d f a t t y a c i d s w i t h v e r y low l e v e l s o f p o l y u n s a t u r a t e d f a t t y a c i d s ( J o h n s o n a n d T r a c e y , 1 9 7 5 ) . As a r e s u l t o f t h e i n c r e a s i n g u s e o f c o n c e n t r a t e s i n r u m i n a n t r a t i o n s a n d g e n e t i c s e l e c t i o n a n d b r e e d i n g d e s i g n e d t o i n c r e a s e p r o d u c t i v i t y , t h e d o m e s t i c r u m i n a n t h a s a h i g h c a p a c i t y t o s y n t h e s i z e a n d d e p o s i t t r i g l y c e r i d e s i n a d i p o s e t i s s u e a n d t o a l e s s e r e x t e n t , i n m i l k ( S c o t t a n d C o o k , 1 9 7 5 ) . 27 O p i n i o n s a n d r e s e a r c h f i n d i n g s h a v e o s c i l l a t e d b e t w e e n i m p l i c a t i n g s a t u r a t e d f a t s among t h e c a u s e s o f a t h e r o s c l e r o s i s a n d f i n d i n g t hem n o t t o be o f i m p o r t a n c e . H o w e v e r , t h e r e h a s b e e n s u f f i c i e n t c o n c e r n a b o u t t h e i r p o s s i b l e i n v o l v e m e n t t o h a v e s t i m u l a t e d c o n s i d e r a b l e r e s e a r c h a c t i v i t y s i n c e 1969, t o c i r c u m v e n t t h e p r o c e s s o f b i o h y d r o g e n a t i o n i n t h e r umen. When S c o t t e t a l . ( 1 9 7 0 ) d e v e l o p e d a p r o c e s s f o r p r o d u c i n g p r o t e c t e d p o l y u n s a t u r a t e d l i p i d s , i t was r e a l l y o n l y v i e w e d a s b e i n g o f a c a d e m i c i n t e r e s t a s a n e f f e c t i v e b i o c h e m i c a l a n d p h y s i o l o g i c a l r e s e a r c h t o o l . H o w e v e r , when i t was shown t h a t w h o l e s e e d s c o u l d be u s e d t o p r o v i d e t h e o i l a n d most o f t h e p r o t e i n ( S c o t t e t a l . , 1972) t h e e c o n o m i c v i a b i l i t y o f t h e p r o c e s s i m p r o v e d . a . P o l y u n s a t u r a t e d M i l k a n d D a i r y P r o d u c t s T h e f i r s t work on f e e d i n g p r o t e c t e d p o l y u n s a t u r a t e d l i p i d s t o e l e v a t e t h e p o l y u n s a t u r a t e d f a t t y a c i d l e v e l o f m i l k f a t was c a r r i e d o u t by S c o t t e t a l . ( 1 9 7 0 ) u s i n g a p r o t e c t e d l i p i d s u p p l e m e n t made f r o m l i n s e e d o i l - c a s e i n . T h e s u p p l e m e n t when f e d t o g o a t s , r a i s e d t h e l e v e l o f m i l k f a t l i n o l e n i c a c i d f r o m 1-2% t o 2 1 - 2 5 % . S i n c e t h i s e a r l i e s t w o rk, many r e s e a r c h e r s h a v e c o n d u c t e d t r i a l s on t h e f e e d i n g o f p r o t e c t e d p o l y u n s a t u r a t e d l i p i d s t o r u m i n a n t s . T h e p r o p o r t i o n o f C18:3 was i n c r e a s e d f r o m 1-2% t o 2 0 - 2 5 % a n d t h e p r o p o r t i o n o f C18:2 was r a i s e d f r o m 2-3% t o 9-11% i n m i l k o f g o a t s f e d p r o t e c t e d l i n s e e d o i l - c a s e i n f o r 4 d a y s ( S c o t t e t a l , 1 9 7 1 ) . A s i m i l a r r e s p o n s e was o b s e r v e d w i t h g o a t s f e d a p r o t e c t e d s a f f l o w e r o i l p r e p a r a t i o n ( S c o t t e t a l . , 1 9 7 2 ) . 28 The l e v e l o f C18:2 i n t h e m i l k i n c r e a s e d f r o m 3-4% t o 2 0 - 3 0 % . R e s e a r c h e r s f e e d i n g p r o t e c t e d s a f f l o w e r o i l t o cows h a v e r e p o r t e d i n c r e a s e s i n m i l k f a t C18:2 f r o m 2-3% t o 3 5 % ( C o o k e t a l . , 1972; Plowman e t a l . , 1972; B i t m a n e t a l . , 1973; G o e r i n g e t a l . , 1976; Wrenn e t a _ l . , 1 9 7 7 ) . S u n f l o w e r o i l s u p p l e m e n t s h a v e p r o d u c e d i n c r e a s e s o f C18:2 f r o m 3.5 t o 16.7% i n ewe's m i l k ( P a l m q u i s t e t a l . , 1977) a n d f r o m 2.5 t o 30% i n cow's m i l k ( C h a n d l e r , et_ a l . , 1973; Wrenn e t a l . , 1976; Y a n g e t a l . , 1 9 7 8 ) . Once i t h a d b e e n d e m o n s t r a t e d t h a t p o l y u n s a t u r a t e d m i l k c o u l d be p r o d u c e d , r e s e a r c h was c o n d u c t e d t o i n v e s t i g a t e t h e p h y s i c a l , c h e m i c a l a n d m a n u f a c t u r i n g p r o p e r t i e s o f t h i s m i l k . I t was f o u n d p o s s i b l e t o m a n u f a c t u r e p o l y u n s a t u r a t e d m i l k , c r e a m , i c e c r e a m , w h i p p i n g c r e a m , b u t t e r , y o g h u r t , s o f t a n d h a r d c h e e s e s a n d s o u r c r e a m p r o d u c t s ( H a r r a p , 1973; H a a s e , 1 9 7 7 ) . b. P o l y u n s a t u r a t e d Body L i p i d s Work on p o l y u n s a t u r a t e d b o d y l i p i d s b e g a n a t t h e same t i m e a s r e s e a r c h on p o l y u n s a t u r a t e d m i l k . Cook e t a l . ( 1 9 7 0 ) o b s e r v e d t h a t 8-10 week o l d l a m b s f e d 175 g o f p r o t e c t e d s a f f l o w e r o i l f o r 3-6 w e e k s , h a d C18:2 l e v e l s i n d e p o t f a t s o f 1 1 . 3 - 1 8 . 6 % c o m p a r e d t o 1.6-4.4% f o r c o n t r o l l a m b s . R e s e a r c h e r s h a v e r e p o r t e d f e e d i n g p r o t e c t e d s a f f l o w e r o r s u n f l o w e r o i l t o c a l v e s , s t e e r s , l a m b s o r s h e e p w i t h r e s u l t a n t i n c r e a s e s i n d e p o t C18:2 l e v e l s f r o m 4.0% t o a s h i g h a s 40% ( F a i c h n e y , e t a l . , 1972; E d m ondson e t a l . , 1974; G a r r e t t e t a l . , 1976a; Hogan a n d Hogan et_ a l . , 1 9 7 6 ) . 29 3. H i g h E n e r g y P r o t e c t e d L i p i d s V a r i o u s p r o t e c t e d l i p i d s h a v e b e e n f e d t o d a i r y cows t o i n v e s t i g a t e t h e i r e f f e c t s on m i l k y i e l d a n d c o m p o s i t i o n . T h e m a j o r i t y o f r e s e a r c h a i m e d a t i m p r o v i n g m i l k y i e l d w i t h p r o t e c t e d l i p i d s h a s b e e n c o n d u c t e d w i t h p r o t e c t e d t a l l o w ( P T ) . T h e f o l l o w i n g s e c t i o n s on m i l k y i e l d a n d m i l k c o m p o s i t i o n a r e b a s e d on t h e l i t e r a t u r e a v a i l a b l e f o r PT o n l y ( t h e s e s u p p l e m e n t s c o n s i s t e d o f 60% s o y b e a n m e a l : 4 0 % t a l l o w u n l e s s o t h e r w i s e s p e c i f i e d ) . a . M i l k Y i e l d When r e v i e w i n g t h e l i t e r a t u r e i t was d i s c o v e r e d t h a t t h e PT c o n s u m p t i o n on t h e v a r i o u s t r i a l s was n o t e x p r e s s e d i n a common f o r m . T h e l e v e l o f PT was e x p r e s s e d a s a p e r c e n t a g e o f t h e c o n c e n t r a t e , a p e r c e n t a g e o f t h e t o t a l r a t i o n , o r a s a q u a n t i t y c o n s u m e d / c o w / d a y . F o r p u r p o s e s o f c o m p a r i s o n i n t h i s r e v i e w , PT l e v e l was e x p r e s s e d a s a p e r c e n t a g e o f t h e t o t a l . d i e t a n d a s k g / d a y , w h e r e p o s s i b l e . M i l k y i e l d r e s p o n s e s t o PT, w i t h v e r y few e x c e p t i o n s , were p o s i t i v e up t o a n i n t a k e o f a p p r o x i m a t e l y 2.5 kg P T / d a y a n d t h e r e a f t e r t h e y were e x t r e m e l y v a r i a b l e . A summary o f p r o d u c t i v e r e s p o n s e s t o p r o t e c t e d t a l l o w f r o m t h e l i t e r a t u r e i s p r e s e n t e d i n T a b l e 1. The l o w e s t i n t a k e s o f PT r e p o r t e d i n t h e l i t e r a t u r e , w ere 0.36 a n d 0.69 kg P T / d a y , f e d t o cows on p a s t u r e ( F i s h e r , 1 9 7 9 ) . M i l k y i e l d i n c r e a s e s were n o t s i g n i f i c a n t a t t h e s e l e v e l s o f PT i n t a k e . On t h e o t h e r h a n d , m i l k p r o d u c e d p e r u n i t o f g r a i n 30 T A B L E 1. RESPONSES TO PROTECTED TALLOW FROM THE L I T E R A T U R E . # COWS INTAKES PRODUCTIVE RESPONSES/DAY PER ===== = == = == = = ====== = ==== = === = ======== = = = = = == = === = = REFERENCE TREAT P T 1 TALLOW 2 MILK FCM FAT PROTEIN ( k g / c o w / d a y ) (%) F i s h e r 1979 12 .36 .16 + .3 + .5 + .03 + .02 F i s h e r 1979 12 .69 .31 + .7 + 1 . 1 + .13 - .02 Sharma e t a l . , 1978 12 .72 .29 + .5 + 1 .4 + . 1 4 - .21 B i n e s e t a l . , 1 978 7 1 .21 .48 + 3.9 + 4.5 + . 1 4 - .11 Sharma e t a l . , 1 978 12 1.31 .52 + .8 + 1 .7 + .26 - .29 B i n e s e t a l . , 1978 7 1 .48 .59 + 2.1 + 2.6 + . 1 4 - .21 K r o n f e l d e t a l . , 1 980 6 1 .65 .66 -1 .0 + 1 .0 + .62 - .10 Sharma e t a l . , 1 978 12 1 .78 .71 + 1 .0 + 3.3 + .57 - .32 B i n e s e t a l . , 1978 7 2.02 .81 + 2.3 + 4.4 + .58 - .10 Wrenn e t a l . , 1 978 4 2.13 .85 + 1 .9 + 2.2 + .10 - .20 K r o n f e l d e t a l . , 1980 6 2.44 .98 + 1 .6 + 2.5 + .26 0.00 K r o n f e l d e t a l . , 1 980 6 2.47 .99 + .3 + 1 .4 + .29 + .02 M a c l e o d e t a l . , 1 977 12 2.21 1 .00 + .3 + 4.0 + .48 - .22 B i n e s e t a l . , 1 978 7 2.79 1.12 + 1 .9 + 3.5 + .48 - .36 M a c l e o d e t a l . , 1977 1 2 2.51 1.13 - .8 + 1 .4 + .38 - .17 B i n e s e t a l . , 1978 7 2.88 1.15 + 1 .2 + 2.7 + .46 - .14 D u n k l e y e t a l . , 1 977 13 2.97 1.19 N.R. 3 N.R. + .87 - .15 S m i t h e t a l . , 1978 1 3 1 .97 1.19 - .4 + 3.8 + .90 N.R. M a c l e o d e t a l . , 1977 12 2.82 1 .27 + 3.6 + 4.6 + .79 - .05 S t o r r y e t a l . , 1974a 4 1 .90 1 .27 + 1 .2 + 4.4 + 1 .63 N.R. M a c l e o d e t a l . , 1977 12 3.30 1 .49 -2.0 + 3.2 + .73 - .31 B i n e s e t a l . , 1978 7 3.81 1 .52 -4.3 -2.4 + .67 - .32 D u n k l e y e t a l . , 1977 1 3 5.10 2.04 N.R. N.R. + .91 - .33 S m i t h e t a l . , 1978 13 5.10 2.04 -1 .3 + 3.9 + 1 .10 N.R. 1 P r o t e c t e d t a l l o w ; 2 c o n t a i n e d i n t h e PT; 3 n o t r e p o r t e d 31 i n t a k e , a n d 4% f a t - c o r r e c t e d m i l k (FCM) b o t h w e r e i n c r e a s e d w i t h e a c h i n c r e m e n t o f PT a n d w e r e s i g n i f i c a n t l y h i g h e r i n t h e d i e t s u p p l y i n g 0.69 kg P T / d a y , t h a n i n t h e c o n t r o l . One- c o m p l i c a t i o n i n t h i s t r i a l was t h a t t h e r a t i o n s w e r e p e l l e t e d a n d i t i s p o s s i b l e t h a t s u c h t r e a t m e n t c o u l d h a v e d i s r u p t e d t h e s t r u c t u r a l i n t e g r i t y o f t h e p r o t e i n - t a l l o w m a t r i x , t h u s r e d u c i n g t h e d e g r e e o f p r o t e c t i o n o f t h e PT. I n a L u c a s s w i t c h - b a c k d e s i g n w i t h p e r i o d s 5 weeks i n l e n g t h , cows i n e a r l y l a c t a t i o n r e c e i v i n g 0.72 kg P T / d a y i n c r e a s e d m i l k y i e l d f r o m 22.3 t o 22.8 k g / c o w / d a y ( S h a r m a e t a l . , 1 9 7 8 ) , o r e s s e n t i a l l y no i n c r e a s e a t a l l . A 13 week c o n t i n u o u s f e e d i n g t r i a l was c o n d u c t e d ( B i n e s e t a l . , 1978) w i t h F r i e s i a n s , i m m e d i a t e l y p o s t - c a l v i n g . T h e f i r s t 6 weeks c o n s t i t u t e d a b u i l d - u p p e r i o d d u r i n g w h i c h t i m e PT i n t a k e s w e r e g r a d u a l l y i n c r e a s e d . T h e a v e r a g e i n t a k e f o r one g r o u p d u r i n g weeks 1-6 was 1.21 kg P T / c o w / d a y , w h i c h r e s u l t e d i n an i n c r e a s e i n m i l k y i e l d o v e r t h e c o n t r o l o f 164 kg i n t o t a l , o r 3.9 k g / c o w / d a y . D u r i n g w eeks 7-13 p o s t - p a r t u m t h e same g r o u p c o n s u m e d 1.48 kg P T / c o w / d a y a n d m i l k y i e l d i n c r e a s e d by 105 kg/cow, r e p r e s e n t i n g a d a i l y i n c r e a s e o f 2.1 kg/cow ( B i n e s e t a l . , 1 9 7 8 ) . T h e r e s p o n s e o f t h i s p a r t i c u l a r g r o u p t o PT was n o t t e s t e d s e p a r a t e l y f o r s t a t i s t i c a l s i g n i f i c a n c e . I n t h e t r i a l m e n t i o n e d e a r l i e r w i t h t h e L u c a s s w i t c h - b a c k d e s i g n ( S h a r m a e t a l . , 1978) cows w i t h a PT i n t a k e o f 1.31 k g / d a y showed a n o n - s i g n i f i c a n t i n c r e a s e i n m i l k y i e l d o f o n l y 0.8 k g / d a y . I n l i g h t o f t h e f a c t t h a t t h e l e v e l o f e n e r g y i n t a k e o f a cow h a s l o n g t e r m e f f e c t s on l a c t a t i o n p e r f o r m a n c e , t h e 32 s w i t c h - b a c k d e s i g n u s e d , w i t h p e r i o d s o n l y 5 weeks i n l e n g t h , may h a v e r e d u c e d o r m a s k e d t h e t r e a t m e n t e f f e c t due t o a c a r r y o v e r o f t h e cow's e n e r g y s t a t u s f r o m one p e r i o d t o t h e n e x t . K r o n f e l d e_t a _ l . ( 1 9 8 0 ) r e p o r t e d a d e c r e a s e i n m i l k y i e l d o f 1.0 k g / c o w / d a y by cows f e d 1.65 kg P T / d a y d u r i n g weeks 10-16 o f l a c t a t i o n . A n e g a t i v e m i l k y i e l d r e s p o n s e a t t h i s l e v e l o f s u p p l e m e n t a t i o n i s somewhat o f a n a n o m a l y . H o w e v e r , m i l k y i e l d , a t t h i s s t a g e o f t h e l a c t a t i o n , h a d a l r e a d y p e a k e d a n d was i n t h e d e c l i n i n g p h a s e when t h e c o w s ' e n e r g y demands were no l o n g e r c r i t i c a l , a n d FCM s howed an i n c r e a s e o f 1.0 k g / c o w / d a y w i t h t h e PT. I n t h i s same t r i a l , t h e f e e d i n g o f h i g h e r l e v e l s o f PT d u r i n g weeks 2-10, r e s u l t e d i n i n c r e a s e s i n m i l k y i e l d a n d FCM ( t o be d i s c u s s e d l a t e r ) i n d i c a t i n g t h e r e was a p o s i t i v e m i l k y i e l d r e s p o n s e t o PT i n t h e r a t i o n up t o week 10 o f l a c t a t i o n b u t n o t l a t e r . A t a s l i g h t l y h i g h e r PT i n t a k e o f 1.78 k g / c o w / d a y , cows i n a t r i a l w i t h r e s t r i c t e d f e e d i n g o f r o u g h a g e a n d c o n c e n t r a t e s i n c r e a s e d m i l k y i e l d by 1.0 k g / d a y a n d i n c r e a s e d FCM s i g n i f i c a n t l y by 3.3 k g / c o w / d a y o v e r c o n t r o l s ( S h a r m a e t a l . f 1 9 7 8 ) . I n a c h a n g e - o v e r d e s i g n i n v o l v i n g 4 cows i n t h e i r f i f t h m o n t h o f l a c t a t i o n , cows were f e d a h i g h r o u g h a g e r a t i o n , a l o w r o u g h a g e r a t i o n , a l o w r o u g h a g e r a t i o n s u p p l e m e n t e d w i t h 1.9 kg P T / c o w / d a y ( c a s e i n : t a l l o w , 1 : 2 ) , a n d f i n a l l y a low r o u g h a g e r a t i o n s u p p l e m e n t e d w i t h m o l a s s e s ( S t o r r y e_t a _ l . , 1 9 7 4 a ) . T h e n a t u r a l d e c l i n e i n m i l k y i e l d a s s o c i a t e d w i t h t h e a d v a n c e i n s t a g e o f l a c t a t i o n , was p a r t l y a r r e s t e d w i t h PT s u p p l e m e n t a t i o n , w i t h a r e c o v e r y i n m i l k y i e l d o f a b o u t 1.2 k g / c o w / d a y a n d a n 33 i n c r e a s e i n FCM o f 4.4 k g / c o w / d a y . B i n e s e t a l . ( 1 9 7 8 ) o b s e r v e d a m i l k y i e l d i n c r e a s e o f 2.3 k g / c o w / d a y o v e r t h e c o n t r o l when cows i n t h e i r f i r s t 6 weeks o f l a c t a t i o n r e c e i v e d 2.02 kg P T / d a y . I n a n o t h e r t r i a l c o n d u c t e d t o c o m p a r e p r o t e c t e d a n d u n p r o t e c t e d t a l l o w , 4 cows b e t w e e n 1 a n d 3 m o n t h s p o s t - c a l v i n g w e r e f e d a c o n c e n t r a t e p r o v i d i n g 2.13 kg P T / c o w / d a y (Wrenn e t a l . , 1 9 7 8 ) . M i l k y i e l d i n c r e a s e d s i g n i f i c a n t l y by 1.9 k g / c o w / d a y o v e r c o n t r o l s . M a c l e o d e_t a _ l . ( 1 9 7 7 ) c o n d u c t e d a s w i t c h - b a c k t r i a l w i t h r o u g h a g e a n d c o n c e n t r a t e o f f e r e d a d l i b i t u m , w h e r e PT ( 4 5 % t a l l o w ) i n t a k e was 2.21 k g / c o w / d a y . T h e r e was o n l y a s m a l l i n c r e a s e i n m i l k y i e l d ( 0 . 3 k g / c o w / d a y ) , a l t h o u g h FCM i n c r e a s e d s i g n i f i c a n t l y ( 4 . 0 k g / c o w / d a y ) . A c o n t i n u o u s f e e d i n g t r i a l was c o n d u c t e d w i t h 12 H o l s t e i n s m a t c h e d i n t o p a i r s b a s e d on m i l k p r o d u c t i o n d u r i n g t h e i r f i r s t week o f l a c t a t i o n ( K r o n f e l d e t a l . , 1 9 8 0 ) . Cows r e c e i v i n g 2.44 a n d 2.47 kg P T / d a y p r o d u c e d 1.6 a n d 0.3 kg more m i l k / d a y a n d 2.5 a n d 1.4 kg more FCM/day t h a n c o n t r o l s , r e s p e c t i v e l y . A t p r o t e c t e d t a l l o w i n t a k e s a b o v e 2.5 k g / c o w / d a y m i l k y i e l d r e s p o n s e s w e r e e x t r e m e l y v a r i a b l e . I n t a k e s o f PT ( o r t a l l o w ) o f : 2 . 7 9 ( 1 . 1 2 ) , 2 . 8 8 ( 1 . 1 5 ) o r 2 . 8 2 ( 1 . 2 7 ) k g / c o w / d a y r e s u l t e d i n m i l k y i e l d i n c r e a s e s o f 1.9, 1.2 a n d 3.6 k g / c o w / d a y , r e s p e c t i v e l y ( B i n e s e t a l . , 1978; M a c l e o d e t a _ l . , '1977). On t h e o t h e r h a n d , PT i n t a k e s o f 2 . 5 1 ( 1 . 1 3 ) a n d 2 . 9 7 ( 1 . 1 9 ) k g / c o w / d a y r e s u l t e d i n d e c r e a s e s i n m i l k y i e l d s o f 0.8 k g / c o w / d a y ( M a c l e o d e t a l . , 1977) a n d 0.4 k g / c o w / d a y ( S m i t h e t a l . , 1 9 7 8 ) . I n t h e f o r m e r t r i a l a s w i t c h - b a c k d e s i g n was e m p l o y e d w i t h v e r y s h o r t 34 p e r i o d s o f 2 w e e k s . T h i s w o u l d m i n i m i z e t h e e f f e c t s o f PT i n t h e r a t i o n . FCM d i d , h o w e v e r , i n c r e a s e s i g n i f i c a n t l y by 1.4 k g / c o w / d a y o v e r c o n t r o l s . I n t h e l a t t e r t r i a l , FCM i n c r e a s e d s i g n i f i c a n t l y by 3.8 kg/cow o v e r c o n t r o l s . PT i n t a k e s o f 3.3 k g / c o w / d a y o r g r e a t e r , c o n s i s t e n t l y r e s u l t e d i n d e c r e a s e s i n m i l k y i e l d s . Cows f e d 3 . 3 0 ( 1 . 4 9 ) , 3 . 8 1 ( 1 . 5 2 ) o r 5 . 1 0 ( 2 . 0 4 ) kg P T ( o r t a l l o w ) / d a y s u f f e r e d n o n -s i g n i f i c a n t m i l k y i e l d d e c r e a s e s o f 2.0 k g / c o w / d a y ( M a c l e o d e t a l . , 1 9 7 7 ) , 4.3 k g / c o w / d a y ( B i n e s e t a l . , 1978) a n d 1.3 k g / c o w / d a y ( S m i t h e t a l . , 1 9 7 8 ) , r e s p e c t i v e l y . B i n e s e t a l . ( 1 9 7 8 ) r e p o r t some f i n d i n g s w h i c h h e l p e x p l a i n t h e s e m i l k y i e l d r e s p o n s e s . F i r s t l y , 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 amount o f t o t a l f a t t y a c i d d i g e s t e d a n d f a t t y a c i d i n t a k e was l i n e a r o n l y up t o a n i n t a k e o f a p p r o x i m a t e l y 1.2 kg f a t t y a c i d s / c o w / d a y ( e q u i v a l e n t t o a b o u t 3.0 kg P T / c o w / d a y ) . S e c o n d l y , when t h e p r o p o r t i o n o f d i g e s t e d e n e r g y i n t h e f o r m o f f a t t y a c i d s e x c e e d e d 18%, t h e d i g e s t i o n o f f a t t y a c i d s a n d o f t o t a l e n e r g y became l e s s e f f i c i e n t . T h i r d l y , t h e y i e l d s o f m i l k a n d i t s c o n s t i t u e n t s were i n c r e a s e d w i t h t h e l i p i d s u p p l e m e n t e d r a t i o n s u n t i l t h e p r o p o r t i o n o f d i g e s t e d f a t t y - a c i d e n e r g y r e a c h e d 19% a n d t h e r e a f t e r r e s p o n s e s w e r e n e g a t i v e . 35 b . M i l k C o m p o s i t i o n i . F a t I n a l l r e p o r t s r e v i e w e d on f e e d i n g p r o t e c t e d t a l l o w t o d a i r y c o w s , m i l k f a t % e i t h e r i n c r e a s e d o r r e m a i n e d u n c h a n g e d , b a s e d on t h e a c t u a l m i l k f a t % v a l u e s . F i s h e r ( 1 9 7 9 ) r e p o r t e d m i l k f a t % i n c r e a s e s o f 0.03 a n d 0.13 a t PT i n t a k e s / c o w / d a y o f 0.36 a n d 0.69 k g , r e s p e c t i v e l y . A t 0.72 kg P T / c o w / d a y , w h i c h a p p r o x i m a t e s t h e h i g h e r l e v e l u s e d by F i s h e r ( 1 9 7 9 ) , S h a r m a e t a l . ( 1 9 7 8 ) o b s e r v e d a n o n - s i g n i f i c a n t i n c r e a s e i n f a t % o f 0.14. I n one c o n t i n u o u s f e e d i n g t r i a l t h e i n c o r p o r a t i o n o f 1.21 o r 1.48 kg P T / c o w / d a y r e s u l t e d , i n b o t h c a s e s , i n a f a t % i n c r e a s e o f o n l y 0.14 ( B i n e s e t a l . , 1978) w h e r e a s cows r e c e i v i n g 1.31 kg P T / d a y i n c r e a s e d m i l k f a t % by 0.26 ( S h a r m a e t a l . , 1 9 7 8 ) . A t s l i g h t l y h i g h e r l e v e l s o f PT i n t a k e , f a t % r e s p o n s e c o n t i n u e d t o r i s e . R e s u l t s f r o m t r i a l s w i t h 1.65 a n d 2.02 kg P T / c o w / d a y showed m i l k f a t % r o s e by 0.62 a n d 0.58, r e s p e c t i v e l y ( K r o n f e l d e t a l . , 1980; B i n e s e t a l . , 1 9 7 8 ) , a n d a t 1.78 kg P T / c o w / d a y f a t t e s t i n c r e a s e d s i g n i f i c a n t l y by 0.57 ( S h a r m a e t a l . , 1 9 7 8 ) . T h i s i s n o t t o s a y t h a t f a t t e s t r e s p o n s e s w e r e c o n s i s t e n t b e c a u s e a t 2.13 kg P T / c o w / d a y Wrenn et_ a l . ( 1 9 7 8 ) r e p o r t e d an i n c r e a s e i n m i l k f a t % o f j u s t 0.10, t h i s r e s p o n s e n o t r e a c h i n g s i g n i f i c a n c e . F o r P T ( o r a c t u a l t a l l o w ) i n t a k e s o f 2 . 4 4 ( 0 . 9 8 ) , 2 . 2 1 ( 1 . 0 0 ) , 2 . 4 7 ( 0 . 9 9 ) , 2 . 7 9 ( 1 . 1 2 ) , 2 . 5 1 ( 1 . 1 3 ) a n d 2 . 8 8 ( 1 . 1 5 ) k g / c o w / d a y , 36 m i l k f a t % i n c r e a s e d by 0.26, 0.48, 0.29, 0.48, 0.38 a n d 0.46, r e s p e c t i v e l y ( K r o n f e l d e t a l . , 1980; B i n e s e t a _ l . , l 9 7 8 ; M a c l e o d e t a l . , 1977) . F a t t e s t c o n t i n u e d t o i n c r e a s e w i t h f u r t h e r i n c r e m e n t s o f P T . M a c l e o d e t a l . ( 1 9 7 7 ) r e p o r t e d t h a t cows f e d 2.82 kg P T / d a y s i g n i f i c a n t l y i n c r e a s e d f a t t e s t by 0.79. S m i t h e t a l . ( 1 9 7 8 ) d e m o n s t r a t e d a s i g n i f i c a n t i n c r e a s e o f 0.9 i n m i l k f a t % o f cows f e d 2.97 kg P T / d a y . A t i n t a k e s o f 3.30, 3 .81 a n d 5.10 kg P T / c o w / d a y , i n c r e a s e s i n m i l k f a t % w e r e 0.73, 0.67 a n d 1.10, r e s p e c t i v e l y ( B i n e s e t a l . , 1978; S m i t h e t a l . , 1978; M a c l e o d e_t aJL. , 1 9 7 7 ) , a l l r e a c h i n g s i g n i f i c a n c e a t t h e P < .05 l e v e l . T a b l e 1 s u m m a r i z e s t h e m i l k f a t p e r c e n t a g e r e s p o n s e s t o PT. Due t o t h e o b s e r v a t i o n t h a t f a t t e s t i n c r e a s e d i n r e s p o n s e t o PT i n a l l t r i a l s r e v i e w e d , a n d m i l k y i e l d i n c r e a s e d i n a l m o s t a l l t r i a l s , i t f o l l o w s t h a t f a t y i e l d i n c r e a s e d i n t h e m a j o r i t y o f c a s e s . i i . P r o t e i n P r o t e i n % i n m i l k c o n s i s t e n t l y d e c l i n e d w i t h r a t i o n s c o n t a i n i n g PT, w i t h v e r y few e x c e p t i o n s ( D u n k l e y e t a l . , 1977; M a c l e o d e t a l . , 1977; B i n e s e t a l . , 1978; S h a rma e t a l . , 1978; F i s h e r , 1 9 7 9 ) . T h e m a g n i t u d e s o f t h e d e c r e a s e s , shown i n T a b l e 1, were n o t w e l l c o r r e l a t e d w i t h t h e l e v e l o f PT i n t a k e . F r e e f a t h a s b e e n shown t o r e d u c e m i l k p r o t e i n y i e l d ( S t o r r y e t a l . , 1974a; B a n k s e t a l . , 1976) a n d w o u l d t e n d t o i n d i c a t e t h a t t h e PT was n o t w e l l p r o t e c t e d . P r o t e i n y i e l d r e s p o n s e s w e r e v a r i a b l e . I f t h e m i l k y i e l d 37 i n c r e a s e s w e r e l a r g e e n o u g h t o o v e r c o m e t h e d e c r e a s e s i n p r o t e i n %, t h e n p r o t e i n y i e l d s i n c r e a s e d ( B i n e s , e t a l . , 1978; F i s h e r , 1979) a l t h o u g h n o t s i g n i f i c a n t l y . O t h e r w i s e , m i l k p r o t e i n y i e l d a l o n g w i t h p r o t e i n % d e c r e a s e d ( M a c l e o d et_ a l . , 1977; B i n e s e t a l . r 1978; Sharma e t a l . , 1978; S m i t h e t a l . , 1 9 7 8 ) . i i i . L a c t o s e L a c t o s e % i n m i l k g e n e r a l l y d e c r e a s e d w i t h PT ( D u n k l e y e t a l . , 1977; M a c l e o d e t a l . , 1977; B i n e s e t a l . , 1978; F i s h e r , 1979) a l t h o u g h t h e s e d e c r e a s e s were o n l y s i g n i f i c a n t i n t h e s t u d y o f M a c l e o d e t a l . ( 1 9 7 7 ) . T h e work o f B i n e s et_ a l . ( 1 9 7 8 ) r e p o r t e d an e x c e p t i o n t o t h i s p a t t e r n w i t h i n c r e a s e s i n l a c t o s e % o f 0.04, 0.01 a n d 0.15 r e s u l t i n g a t PT i n t a k e s o f 1.21, 1.48 a n d 2.88 k g / c o w / d a y , r e s p e c t i v e l y . L a c t o s e y i e l d showed i n c r e a s e s up t o a PT i n t a k e o f 2.97 k g / c o w / d a y ( B i n e s e t a l . , 1978; F i s h e r , 1979) w i t h t h e e x c e p t i o n o f t h e s t u d y by M a c l e o d e t a l . ( 1 9 7 7 ) a n d a t 2.97 k g / P T / c o w / d a y o r h i g h e r l a c t o s e y i e l d / c o w / d a y d e c r e a s e d ( D u n k l e y e t a l . , 1977; M a c l e o d e t a l . , 1 9 7 7 ) . 38 c. M i l k F a t S y n t h e s i s The complex c o m p o s i t i o n of m i l k f a t depends on the i n t e g r a t i o n of s e v e r a l b i o c h e m i c a l pathways, which p r o v i d e a b a s i s f o r e x p l a i n i n g the e f f e c t s of n u t r i t i o n on m i l k f a t s e c r e t i o n . In the ruminant the s h o r t - c h a i n f a t t y a c i d s (C4-C10), which r e p r e s e n t about 10% by weight of m i l k f a t t y a c i d s , a r e s y n t h e s i z e d i n the mammary g l a n d w i t h i n the mammary e p i t h e l i a l c e l l , from a c e t a t e and p-OH-butyrate ( S t o r r y , 1972). The l o n g - c h a i n f a t t y a c i d s (C18) c o m p r i s i n g some 40 % by weight of m i l k f a t t y a c i d s , a r e d e r i v e d m a i n l y from the b l o o d plasma t r i g l y c e r i d e s c o n t a i n e d i n the c h y l o m i c r a and v e r y low d e n s i t y l i p o p r o t e i n s which o r i g i n a t e from the d i e t and from a d i p o s e t i s s u e ( P a l m q u i s t and Conrad, 1971; Emery, 1973). F a t t y a c i d s of i n t e r m e d i a t e c h a i n l e n g t h (C12-C16) o r i g i n a t e from b o t h of the s e s o u r c e s ( S t o r r y , 1980). i . Intramammary F a t t y A c i d S y n t h e s i s The b i o c h e m i c a l pathways i n v o l v e d i n the intramammary s y n t h e s i s of f a t t y a c i d s may be summarized as f o l l o w s ( S t o r r y , 1972) : 1. The m a l o n y l pathway o p e r a t i n g i n the c e l l c y t o s o l which i n v o l v e s the c a r b o x y l a t i o n of a c e t y l CoA t o m a l o n y l CoA, f o l l o w e d by subsequent c o n d e n s a t i o n of the m a l o n y l CoA w i t h more m o l e c u l e s of a c e t y l CoA t o g i v e f a t t y a c i d s c o n t a i n i n g up t o 16 carbon atoms, 2. D i r e c t i n c o r p o r a t i o n of p-OH-butyrate as a C4 m o l e c u l e which may s u b s e q u e n t l y be e l o n g a t e d by the f u r t h e r a d d i t i o n s of a c e t y l CoA, 3. I n c o r p o r a t i o n of a c e t a t e i n t o s h o r t and i n t e r m e d i a t e c h a i n a c i d s by the m i t o c h o n d r i a , and 39 4. D e s a t u r a t i o n o f s t e a r i c a n d p a l m i t i c a c i d s . i i . S o u r c e s o f C a r b o n Of t h e f a t t y a c i d s s y n t h e s i z e d w i t h i n t h e mammary g l a n d , 8 0 % a r e f r o m a c e t a t e a n d 2 0 % a r e f r o m p - O H - b u t y r a t e ( S t o r r y , 1980) . p - O H - b u t y r a t e must f i r s t be c o n v e r t e d t o a 4 - c a r b o n p r i m e r ( b u t y r y l CoA) a n d t h e n t o a c e t y l CoA b e f o r e i t c a n be i n c o r p o r a t e d i n t o f a t t y a c i d s b e y o n d t h e f i r s t 4 - c a r b o n u n i t . Bauman e t a l . ( 1 9 7 0 ) h a v e i n d i c a t e d t h a t i n cow mammary t i s s u e , p - O H - b u t y r a t e d e h y d r o g e n a s e , t h e f i r s t enzyme i n t h e c o n v e r s i o n o f p - O H - b u t y r a t e t o a c e t y l CoA, i s l o c a t e d a l m o s t e x c l u s i v e l y i n t h e m i t o c h o n d r i a . T h i s v i r t u a l a b s e n c e o f p - O H - b u t y r a t e d e h y d r o g e n a s e o u t s i d e o f t h e m i t o c h o n d r i a , p r e c l u d e s p-OH-b u t y r a t e f r o m f u r n i s h i n g s i g n i f i c a n t q u a n t i t i e s o f c a r b o n f o r f a t t y a c i d s y n t h e s i s b e y o n d t h e i n i t i a l 4 - c a r b o n u n i t (Bauman a n d D a v i s , 1 9 7 5 ) . F i g u r e 7 o u t l i n e s some p a t h w a y s o p e r a t i n g i n t h e n o n - r u m i n a n t w h i c h a r e l a c k i n g i n t h e r u m i n a n t . S t u d i e s h a v e d e m o n s t r a t e d t h a t r u m i n a n t mammary t i s s u e c a n n o t u s e g l u c o s e a s a c a r b o n s o u r c e f o r f a t t y a c i d s y n t h e s i s ; h o w e v e r , i t r e a d i l y u t i l i z e s a c e t a t e f o r t h i s p u r p o s e (Bauman e t a l . , 1 9 7 3 ) . Work w i t h p e r f u s e d g o a t mammary g l a n d s s u g g e s t e d t h a t b o t h g l u c o s e a n d a c e t a t e c o n t r i b u t e d t o t h e i n t r a -m i t o c h o n d r i a l a c e t y l - C o A p o o l b u t o n l y a c e t a t e c o n t r i b u t e d t o t h e e x t r a - m i t o c h o n d r i a l a c e t y l CoA p o o l w h e r e f a t t y a c i d s y n t h e s i s o c c u r r e d ( H a r d w i c k , 1 9 6 6 ) . Pentose \ NADP+—s Phosphate^ * cycle / NADPH \ fatty acids \ \ * \ \NADP+ y )! / ^ NADPH I o - q l y c e r o l - P y S J | N A D + — yi _ _ J R ** primer NADH N"AD+ , , • ! i: | f malonyl-CoA | NADH - ' \ \ ^ ^ \ acetyl-CoA *-OH ty NADPH \ \ ^ butyrate pyruvate •<—^^NADP+ \ ^ ^acetate • malate ^ ^  ** — ^ NAD+ — ^  **•' v. .NADH ^ ^ a-ketoglut'arate«4>c-ketoglutarate fumarate MITOCHONDRIA CYTOSOL Figure 7. Metabolic pathways present in monogastrics but absent in ruminants. The missing pathways are marked with x s From Bauman and Davis, (1975). 41 C e n t r a l t o t h e u t i l i z a t i o n o f g l u c o s e c a r b o n f o r f a t t y a c i d s y n t h e s i s i s t h e p r e s e n c e o f a n a c t i v e c i t r a t e - c l e a v a g e p a t h w a y . S t u d i e s w i t h mammary t i s s u e s l i c e i n c u b a t i o n s h a v e shown t h a t t h e a c t i v i t i e s o f A T P - c i t r a t e l y a s e a n d N A D P - m a l a t e d e h y d r o g e n a s e ( two o f t h e e n z y m e s i n v o l v e d i n t h e c i t r a t e -c l e a v a g e p a t h w a y ) a r e e x t r e m e l y low i n cow a n d s h e e p mammary t i s s u e s (Bauman e_t a _ l . , 1970; M e l l e n b e r g e r e_t a l . , 1973; Bauman e t a l . , 1973) . The s y n t h e s i s o f b u t y r a t e by an a l t e r n a t e p a t h w a y n o t i n v o l v i n g m a l o n y l - C o A c a n p r o c e e d v i a t h e ^ - r e d u c t i o n p a t h w a y w h i c h i s i n e s s e n c e a r e v e r s a l o f t h e m i t o c h o n d r i a l p - o x i d a t i o n p a t h w a y f o r f a t t y a c i d c a t a b o l i s m (Bauman et. a l . , 1 9 7 4 ) . T h e s i g n i f i c a n c e o f t h i s a l t e r n a t e p a t h w a y when l i p i d s a r e a d d e d t o t h e d i e t w i l l be d i s c u s s e d l a t e r . i i i . Mammary U p t a k e a n d D e s a t u r a t i o n o f P l a s m a F a t t y a c i d s S t u d i e s w i t h i n f u s i o n s o f r a d i o a c t i v e s t e a r i c a c i d i n t o mammary t i s s u e o f g o a t s a n d cows h a v e i n d i c a t e d a s u b s t a n t i a l p o r t i o n was c o n v e r t e d t o o l e i c a c i d , s u g g e s t i n g a mammary d e s a t u r a s e a c t i v i t y ( A n n i s o n e t a l . , 1967; L i n z e l l e t a l . , 1 9 6 7 ) . 42 iv . Contribution of Plasma Lipids to Milk Fat Fatty acids are absorbed from the small i n t e s t i n e , re-e s t e r i f i e d to form t r i g l y c e r i d e s in the i n t e s t i n a l mucosa and transported as t r i g l y c e r i d e s in the chylomicra of lymph and plasma (Robinson, 1970). During passage through the c a p i l l a r y endothelium of the mammary gland, the plasma t r i g l y c e r i d e s are hydrolyzed by lipoprotein lipase and the fatty acids are absorbed into the i n t r a c e l l u l a r spaces of the mammary tissue and incorporated into milk t r i g l y c e r i d e s (Barry e_t a l . , 1963; Storry, 1980). R e - e s t e r i f i c a t i o n occurs mainly via the phosphatidic acid diglyceride pathway (Storry, 1980). v. The Influence of Protected or Unprotected Lipids on the Yi e l d and Percentage of Milk Fat The knowledge and technology for the production of protected l i p i d s have continually been expanding and improving. Variable quantities of proteins, l i p i d s and aldehydes have been used, and i t becomes very d i f f i c u l t to state what effect a 'protected l i p i d ' has on metabolism or production. A major problem has been that the majority of protected l i p i d supplements used in feeding t r i a l s have been only highly protected, at best (Storry et a l . , 1980). In other words, almost a l l protected l i p i d supplements manufactured to date have contained some unprotected l i p i d . Therefore, when explaining the mechanism of action of a protected l i p i d , one must account for the small proportion of l i p i d which i s delivered to the rumen unprotected, as well as the larger proportion which is liberated in the abomasum. 43 v i . Rumen M i c r o b i a l F a t t y A c i d S y n t h e s i s S u p p l e m e n t s o f o i l s t o t h e d i e t h a v e b e e n shown t o d e c r e a s e i n t r a r u m i n a l s y n t h e s i s o f f a t t y a c i d s a n d t h e r e b y r e d u c e t h e a m o u n t s o f s t e a r i c a n d p a l m i t i c a c i d s , a c i d s c o n t a i n i n g o d d n u m bers o f c a r b o n a t o m s a n d b r a n c h e d c h a i n a c i d s , o f m i c r o b i a l o r i g i n , w h i c h r e a c h t h e s m a l l i n t e s t i n e ( S t o r r y , 1 9 8 0 ) . F r e e l i p i d s h a v e c a u s e d d e c r e a s e s i n t h e a c e t a t e t o p r o p i o n a t e r a t i o i n t h e rumen a s a r e s u l t o f a n i n c r e a s e d p r o p i o n a t e l e v e l c o u p l e d w i t h a d e c r e a s e d a c e t a t e l e v e l (Brumby e t a l . , 1972; D i n i u s e t a l . , 1974; S t o r r y et. a l . , 1 9 7 4 a; P a l m q u i s t a n d J e n k i n s , 1980; S e i n e r a n d S h u l t z , 1 9 8 0 ) . T h e o v e r a l l b a l a n c e b e t w e e n t h e l i p o g e n i c n u t r i e n t s , n a m e l y a c e t i c a c i d , b u t y r i c a c i d a n d l o n g e r - c h a i n f a t t y a c i d s a n d t h e g l u c o g e n i c n u t r i e n t s w h i c h c o n s i s t p r i m a r i l y o f p r o p i o n i c a c i d , g l u c o s e a n d c e r t a i n a m i n o a c i d s c a n be e x p r e s s e d a s t h e a c e t i c a c i d : p r o p i o n i c a c i d r a t i o i n t h e rumen ( S u t t o n , 1 9 8 0 ) . T h i s r a t i o b e a r s a c l o s e , d i r e c t r e l a t i o n t o m i l k f a t p e r c e n t a g e : a s t h e r a t i o d e c r e a s e s s o d o e s m i l k f a t % (Wrenn e t a l . , 1978; P a l m q u i s t a n d J e n k i n s , 1980; S e i n e r a n d S h u l t z , 1 9 8 0 ) . 44 v i i . T h e o r i e s on D e p r e s s e d F a t t y A c i d S y n t h e s i s D e p r e s s e d y i e l d s o f C6-C16 f a t t y a c i d s i n m i l k h a v e b e e n o b s e r v e d by many r e s e a r c h e r s when f a t s , o i l s o r l o n g - c h a i n f a t t y a c i d s h a v e b e e n a d d e d t o t h e d i e t (Brumby e t a l . , 1972; B a n k s e t a l . , 1976; G o e r i n g e t a l . , 1977; Wrenn e t a l . , 1978; S e i n e r a n d S h u l t z , 1 9 8 0 ) . Two t h e o r i e s h a v e b e e n a d v a n c e d t o h e l p e x p l a i n t h e d e c r e a s e i n y i e l d s o f C6-C16 m i l k f a t t y a c i d s w i t h t h e f e e d i n g o f l i p i d s . I t h a s b e e n s u g g e s t e d t h a t t h i s d e p r e s s e d i n t r a m a m m a r y s y n t h e s i s o f f a t t y a c i d s i s r e l a t e d t o : 1. T h e a l t e r e d p r o d u c t i o n o f V F A s i n t h e rumen w h i c h d e c r e a s e s t h e s u p p l i e s o f a c e t a t e a n d 0 - O H - b u t y r a t e t o t h e mammary g l a n d ( S t o r r y , 1970) a n d / o r 2. An i n h i b i t i o n o f r a t e - l i m i t i n g a c e t y l CoA c a r b o x y l a s e a c t i v i t y t h r o u g h i n c r e a s e d mammary u p t a k e o f l o n g - c h a i n f a t t y a c i d s f r o m p l a s m a t r i g l y c e r i d e s ( S t o r r y , 1 9 8 0 ) . P a l m q u i s t a n d J e n k i n s ( 1 9 8 0 ) a r e i n a g r e e m e n t w i t h t h e f i r s t t h e o r y . T h e y s u g g e s t t h e c h a n g e i n t h e rumen a c e t a t e / p r o p i o n a t e r a t i o i n d u c e s a g l u c o g e n i c r e s p o n s e o f a d i p o s e t i s s u e w h i c h c a u s e s i t t o : 1. c o m p e t e w i t h t h e mammary g l a n d f o r l i p o g e n i c s u b s t r a t e , e f f e c t i v e l y r e d u c i n g t h e a c e t a t e a v a i l a b i l i t y t o t h e mammary g l a n d , 2. t a k e up a n d e s t e r i f y i n c r e a s e d a m o u n t s o f d i e t a r y l o n g c h a i n f a t t y a c i d , a n d 3. d e c r e a s e m o b i l i z a t i o n o f a d i p o s e t i s s u e l o n g c h a i n f a t t y a c i d f o r m i l k s y n t h e s i s . T h e f o r m a t i o n o f m a l o n y l CoA i s t h e r a t e - l i m i t i n g s t e p o f t h e m a l o n y l p a t h w a y a n d i s c a t a l y z e d by a c e t y l CoA c a r b o x y l a s e w h i c h i s l o c a t e d b o t h i n t h e c y t o s o l a n d m i c r o s o m e s ( S m i t h 45 e t a l . , 1966; E a s t e r e t a _ l . , 1 9 6 8 ) . T h e a c t i v i t y o f t h i s enzyme h a s b e e n shown t o be r e d u c e d by f r e e f a t t y a c i d s ( B a r t l e y e t a l . , 1 9 6 7 ) . Bauman a n d D a v i s ( 1 9 7 5 ) r e p o r t e d t h a t a c e t y l CoA c a r b o x y l a s e a c t i v i t y was c l o s e l y r e l a t e d t o t h e l i p o g e n i c c a p a c i t y o f cow mammary t i s s u e d u r i n g t h e o n s e t o f l a c t a t i o n . F u r t h e r m o r e , o f t h e e n z y m e s i n v o l v e d i n f a t t y a c i d b i o s y n t h e s i s , o n l y a c e t y l CoA c a r b o x y l a s e a c t i v i t y d e c r e a s e d i n p r o p o r t i o n t o t h e c h a n g e i n t h e r a t e o f f a t t y a c i d s y n t h e s i s (Bauman e_t a l . , 1 9 7 4 ) . T h e s e f i n d i n g s were b a s e d on work w i t h i n v o l u t e d s h e e p mammary t i s s u e . E m e r y ( 1 9 7 3 ) s h o w e d a n i n h i b i t i o n o f mammary de n o v o f a t t y a c i d s y n t h e s i s when l o n g c h a i n f a t t y a c i d s were a d d e d t o t h e d i e t . S e v e r a l s t u d i e s h a v e f o u n d t h a t l o n g - c h a i n p o l y u n s a t u r a t e d f a t t y a c i d s r e d u c e m i l k f a t % more t h a n do s a t u r a t e d l o n g - c h a i n a c i d s ( S t o r r y e t a l . , 1 9 7 4 c ) . I t h a s b e e n s u g g e s t e d t h a t p o l y u n s a t u r a t e d l o n g - c h a i n f a t t y a c i d s i n h i b i t mammary u p t a k e o f p l a s m a f a t t y a c i d s . T h e f a i l u r e o f p r o t e c t e d c o d - l i v e r o i l t o i n c r e a s e m i l k f a t o u t p u t , a n d p a r t i c u l a r l y i t s f a i l u r e t o i n c r e a s e s e c r e t i o n o f C16 a n d C18 a c i d s , i n c o n t r a s t t o t h e r e s u l t s o f f e e d i n g s e v e r e l y h y d r o g e n a t e d c o d - l i v e r " o i l (Brumby e t a l . , 1972) o r o t h e r o i l s c o n t a i n i n g C16 a n d C18 a c i d s ( S t o r r y e t a l . , 1973, 1974b) s u g g e s t s t h e p o l y u n s a t u r a t e d f a t t y a c i d s o f c o d - l i v e r o i l d i r e c t l y i n h i b i t mammary u p t a k e o f p l a s m a f a t t y a c i d s ( S t o r r y e t a l . , 1 9 7 4 c ) . T h e p o l y u n s a t u r a t e d f a t t y a c i d s may h a v e an i n h i b i t o r y e f f e c t on mammary l i p o p r o t e i n l i p a s e ( P a l m q u i s t , 1 9 7 6 ) . 46 M a t t o s a n d P a l m g u i s t ( 1 9 7 4 ) a l o n g w i t h o t h e r r e s e a r c h e r s ( S t o r r y et_ a _ l . , 1973; Wrenn e t a l . , 1978) o b s e r v e d a n i n c r e a s e i n m i l k b u t y r i c a c i d w i t h d e c r e a s e s i n C6-C16 f a t t y a c i d s , when f e e d i n g u n p r o t e c t e d o i l . T h e t h e o r y t h a t t h e i n h i b i t i o n o f s y n t h e s i s by t h e mammary g l a n d o f C6-C16 f a t t y a c i d s i s due t o f e e d b a c k i n h i b i t i o n on a c e t y l CoA c a r b o x y l a s e i n t h e g l a n d , i s s t i l l v i a b l e i n t h i s c a s e . M a t t o s a n d P a l m q u i s t ( 1 9 7 4 ) p r o p o s e d t h a t t h e h i g h e r l e v e l o f m i l k f a t b u t y r i c a c i d was due t o i t s i n d e p e n d e n c e o f t h e m a l o n y l CoA s y n t h e t i c p a t h w a y , a s w e l l a s t o t h e d e c r e a s e d u t i l i z a t i o n o f b u t y r i c a c i d a s a p r e c u r s o r f o r t h e s y n t h e s i s o f t h e l o n g e r c h a i n f a t t y a c i d s t h r o u g h t h e m a l o n y l CoA p a t h w a y . I n a d d i t i o n , a c e t y l CoA i s d i v e r t e d f r o m s y n t h e s i s o f o t h e r s h o r t c h a i n f a t t y a c i d s , t o b u t y r a t e . d . F e e d U t i l i z a t i o n a n d G r o w t h P a r a m e t e r s i . I n t a k e s M o s t r e s e a r c h e r s r e p o r t e d d e c r e a s e s i n f e e d d r y m a t t e r i n t a k e f r o m p r o t e c t e d l i p i d f e e d i n g o f l a m b s ( F a i c h n e y e t a l . , 1973; M a t a - H e r n a n d e z e t a l . , 1978; S h e l l e t a l . , 1 9 7 8 ) , s t e e r s ( F a i c h n e y e t a l . , 1972; D i n i u s e t a l . , 1974, 1975; D r y d e n e t a l . , 1975; G a r r e t t e t ajL. , 1976b; M c C a r t o r a n d S m i t h , 1 9 7 8 ) , a n d h e i f e r s ( R h o d e s e t a l . , 1 9 7 8 ) . W i t h cows r e c e i v i n g more t h a n 1.75 kg P T / d a y , d r y m a t t e r i n t a k e d e c r e a s e d ( M a c l e o d e t a l . , 1977; B i n e s e t a l . , 1978; S h a r m a e t a l . , 1978; S m i t h e t a l . , 1 9 7 8 ) . H o w e v e r , B i n e s e t a l _ . ( 1 9 7 8 ) , Sharma e t a l . ( 1 9 7 8 ) a n d K r o n f e l d e t a l . ( 1 9 8 0 ) r e p o r t e d no s i g n i f i c a n t 47 d i f f e r e n c e s i n d r y m a t t e r i n t a k e s a n d F i s h e r ( 1 9 7 9 ) r e p o r t e d no s i g n i f i c a n t d i f f e r e n c e i n d r y m a t t e r i n t a k e f r o m c o n c e n t r a t e s , when PT i n t a k e s w e r e l e s s t h a n 1.70 k g / c o w / d a y . I n t h e t r i a l o f F i s h e r ( 1 9 7 9 ) cows w e r e on p a s t u r e a n d t h e r e f o r e t o t a l d r y m a t t e r i n t a k e s w e r e n o t known. I n c r e a s e s i n d r y m a t t e r i n t a k e h a v e b e e n r e p o r t e d f o r s h e e p f e d 200 g / d a y o f c a s e i n p r o t e c t e d s a f f l o w e r o i l ( H o g a n e_t a _ l . , 1 9 7 2 ) , a n d f o r cows (Wrenn e t a l . , 1978) . E n e r g y i n t a k e s were shown t o i n c r e a s e f o r l a m b s ( F a i c h n e y e t a l . , 1972, 1973) a n d s h e e p ( H o g a n e t a l . , 1972) f e d PT. Wrenn e t a l . ( 1 9 7 8 ) r e p o r t e d a n i n c r e a s e i n e n e r g y i n t a k e o f cows f e d PT, y e t i n m o s t s t u d i e s t h e r e was no s i g n i f i c a n t e f f e c t o f PT on i n t a k e o f e n e r g y ( M a c l e o d e t a _ l . , 1977; S m i t h et. a l . , 1978; K r o n f e l d e_t a _ l . , 1 9 8 0 ) . D e c r e a s e s i n e n e r g y i n t a k e s w e r e o b s e r v e d f o r s t e e r s f e d 25% PT ( G a r r e t t e t a l . , 1 9 7 6 b ) , 2 0 % p r o t e c t e d s a f f l o w e r o i l ( F a i c h n e y e t a _ l . , 1972) a n d 12% p r o t e c t e d s a f f l o w e r o i l ( D r y d e n e t a l . , 1975) a n d f o r cows f e d PT ( B i n e s e t a l . , 1978) . 48 i i . E f f i c i e n c i e s E f f i c i e n c i e s o f f e e d c o n v e r s i o n h a v e g e n e r a l l y b e e n i m p r o v e d f o r s t e e r s a n d s h e e p on r a t i o n s w i t h p r o t e c t e d l i p i d s ( F a i c h n e y e t a l _ . , 1973; C u i t u n e t a l . , 1975; G a r r e t t e t a l . , 1 9 7 6 a ; M c C a r t o r a n d S m i t h , 1978; S h e l l e t a l . , 1 9 7 8 ) . The e f f i c i e n c y o f u t i l i z a t i o n o f e n e r g y f o r m i l k p r o d u c t i o n by cows f e d PT was i n c r e a s e d by 8 - 13.6% ( K r o n f e l d e t a l . , 1980) a n d 10% ( S m i t h e t a l . , 1978) o v e r c o n t r o l s . B i n e s e t a l . ( 1 9 7 8 ) r e p o r t e d t h a t t h e e f f i c i e n c y o f m i l k p r o d u c t i o n i n c r e a s e d w i t h PT up t o 30 M J / c o w / d a y o f f a t t y a c i d s d i g e s t e d . i i i . A p p a r e n t D i g e s t i b i l i t i e s D i g e s t i b i l i t y o f d r y m a t t e r h a s b e e n shown t o i n c r e a s e w i t h p r o t e c t e d l i p i d s f e d t o s t e e r s ( C u i t u n e_t a l . , 1975) a n d l a m b s ( S h e l l e_t a l . , 1 9 7 8 ) . No s i g n i f i c a n t e f f e c t o f PT on d r y m a t t e r d i g e s t i b i l i t y o f cows was r e p o r t e d by K r o n f e l d a n d D o n o g h u e ( 1 9 8 0 ) , o r S h a r m a e t a l . ( 1 9 7 8 ) . A t l e v e l s o f PT i n t a k e o f 2.78 k g / c o w / d a y o r h i g h e r , d r y m a t t e r d i g e s t i b i l i t y was s i g n i f i c a n t l y d e c r e a s e d ( B i n e s e t a l . , 1 9 7 8 ) . R e s p o n s e s i n d i g e s t i b i l i t y o f f a t o r e t h e r e x t r a c t w e r e e x t r e m e l y c o n s i s t e n t , a l w a y s s h o w i n g i n c r e a s e s w h i c h r e a c h e d s t a t i s t i c a l s i g n i f i c a n c e i n m o s t c a s e s ( D i n i u s e t a _ l . , 1 974; G a r r e t t e t a l . , 1976b; M a c l e o d e t a l . , 1977; B i n e s e t a l . , 1978; K r o n f e l d a n d D o n o g h u e , 1 9 8 0 ) . P r o t e c t e d l i p i d s h a v e c a u s e d r e d u c e d f i b r e d i g e s t i b i l i t y i n many i n s t a n c e s w i t h s t e e r s ( F a i c h n e y e t a l . , 1973; D i n i u s 49 e t a l . , 1974; G a r r e t t e t a l . , 1976b) a n d w i t h l a m b s ( S h e l l e t a l . , 1 978) a n d cows ( B i n e s et_ a _ l . , 1978; K r o n f e l d a n d D o n o g h u e , 1 9 8 0 ) . M a c l e o d e t a l . ( 1 9 7 7 ) r e p o r t e d no s i g n i f i c a n t d i f f e r e n c e i n f i b r e d i g e s t i b i l i t y b e t w e e n PT r a t i o n s a n d c o n t r o l s . T h e e f f e c t o f p r o t e c t e d l i p i d s on n i t r o g e n d i g e s t i b i l i t y i s u n c e r t a i n b e c a u s e p o s i t i v e a n d n e g a t i v e r e s p o n s e s h a v e b e e n o b s e r v e d . I m p r o v e m e n t s i n n i t r o g e n o r p r o t e i n d i g e s t i b i l i t i e s w e re r e p o r t e d f o r l a m b s a n d s h e e p ( H o g a n e t a l . , 1972; S h e l l e t a l . , 1 9 7 8 ) , s t e e r s ( F a i c h n e y et_ a l . , 1973; C u i t u n e t a l . , 1975) a n d h e i f e r s ( K r o n f e l d a n d D o n o g h u e , 1980) w h e r e a s d e c r e a s e s w e r e r e p o r t e d f o r s t e e r s by D i n i u s e t a l . ( 1 9 7 4 ) a n d G a r r e t t e t a l . ( 1 9 7 6 b ) a n d by B i n e s e t a l . ( 1 9 7 8 ) f o r c o w s . No n i t r o g e n d i g e s t i b i l i t y d i f f e r e n c e was f o u n d by M a c l e o d e t a l . ( 1 9 7 7 ) o r Sharma e t a l . ( 1 9 7 8 ) f o r c o w s . K r o n f e l d a n d D o n o g h u e ( 1 9 8 0 ) a n d B i n e s e t a l . ( 1 9 7 8 ) h a v e r e p o r t e d d e c r e a s e s i n c a l c i u m a n d m a g n e s i u m d i g e s t i b i l i t i e s w i t h PT. B i n e s et_ a l . ( 1 9 7 8 ) f o u n d no e f f e c t o f PT on a p p a r e n t d i g e s t i b i l i t y o f p h o s p h o r u s . K r o n f e l d a n d D o n o g h u e ( 1 9 8 0 ) s u g g e s t e d t h a t i n s o l u b l e s o a p s were f o r m e d i n t h e i n t e s t i n e w h i c h t i e d up b o t h c a l c i u m a n d m a g n e s i u m . B i n e s e t a l . ( 1 9 7 8 ) f o u n d t h a t t h e r e were l i n e a r r e l a t i o n s h i p s b e t w e e n a m o u n t s o f n u t r i e n t s a p p a r e n t l y d i g e s t e d a n d t h e i r r e s p e c t i v e d i e t a r y i n t a k e s a n d c o n c l u d e d t h a t low d i g e s t i b i l i t y v a l u e s f o r m a g n e s i u m a n d c a l c i u m w e r e a s s o c i a t e d w i t h l o w i n t a k e s . T h e s e w o r k e r s f e l t t h e i r d i g e s t i b i l i t y m e a s u r e m e n t s g a v e no i n d i c a t i o n t h a t a b s o r p t i o n o f c a l c i u m o r m a g n e s i u m was r e d u c e d t h r o u g h s o a p 50 f o r m a t i o n . S h a rma e t a l . ( 1 9 7 8 ) a n d S t o r r y e t a l . ( 1 9 8 0 ) r e p o r t e d t h e r e w e r e no s i g n i f i c a n t e f f e c t s o f p r o t e c t e d t a l l o w on c a l c i u m , m a g n e s i u m o r p h o s p h o r u s a c t u a l d i g e s t i b i l i t i e s . 51 I I I . EXPERIMENTAL STUDIES I n t h e p r e s e n t s t u d y a c o m p a r i s o n .was made b e t w e e n a c o n t r o l r a t i o n a n d r a t i o n s c o n t a i n i n g c o n c e n t r a t e s e i t h e r w i t h 8% s o y b e a n m e a l - p r o t e c t e d t a l l o w o r 8% c a n o l a m e a l - p r o t e c t e d t a l l o w . I n a d d i t i o n , a s e c o n d c o m p a r i s o n was made b e t w e e n t h e two t y p e s o f p r o t e c t e d t a l l o w . E v a l u a t i o n was b a s e d on p r o d u c t i o n p a r a m e t e r s , i n t a k e s , e f f i c i e n c i e s , a p p a r e n t d i g e s t i b i l i t i e s , a v e r a g e d a i l y g a i n s , b l o o d m e t a b o l i t e s a n d rumen V F A s . A. M a t e r i a l s A n d M e t h o d s 1. F e e d i n g T r i a l a . A n i m a l s T w e n t y - s e v e n d a i r y cows f r o m t h e U n i v e r s i t y h e r d , c o m p r i s e d o f 12 f i r s t - c a l f H o l s t e i n h e i f e r s , 3 H o l s t e i n s i n t h e i r £ 2nd l a c t a t i o n , 4 A y r s h i r e h e i f e r s a n d 8 > 2 n d l a c t a t i o n A y r s h i r e s , w e r e u s e d i n a c o n t i n u o u s f e e d i n g t r i a l w h i c h was c o n d u c t e d f r o m d a y o f c a l v i n g u n t i l t h e e n d o f week 20 o f l a c t a t i o n . 52 b . T r e a t m e n t s T h e t r i a l c o n s i s t e d o f 2 c o n s e c u t i v e p e r i o d s p r e c e d e d by a p r e - p a r t u m p e r i o d d u r i n g w h i c h cows w e r e moved t o i n d i v i d u a l m a t e r n i t y p e n s a p p r o x i m a t e l y 7-10 d a y s p r i o r t o c a l v i n g . D u r i n g t h i s p e r i o d t h e c o n c e n t r a t e s t o be f e d p o s t - c a l v i n g w e r e i n t r o d u c e d a n d g r a d u a l l y i n c r e a s e d t o f a c i l i t a t e rumen m i c r o b i a l a d a p t a t i o n . i . P e r i o d I - T r e a t m e n t P e r i o d (weeks 1-15) Cows we r e r a n d o m l y a s s i g n e d , w i t h i n b r e e d a n d l a c t a t i o n number ( f i r s t l a c t a t i o n v e r s u s > 2nd l a c t a t i o n ) , t o one o f 3 c o n c e n t r a t e s : a c o n t r o l , 16% c r u d e p r o t e i n c o n c e n t r a t e , a 16% c r u d e p r o t e i n c o n c e n t r a t e c o n t a i n i n g 8% s o y b e a n m e a l ( G l y c i n e max) p r o t e c t e d t a l l o w (PROTEC S ) , o r a 16% c r u d e p r o t e i n c o n c e n t r a t e c o n t a i n i n g 8% C a n d l e c a n o l a m e a l ( B r a s s i c a c a m p e s t r i s ) p r o t e c t e d t a l l o w (PROTEC R ) 1 . D u r i n g weeks 1, 2, a n d 3-15, cows were o f f e r e d c o n c e n t r a t e s a t 50, 60, a n d 7 0 % o f t h e r a t i o n , r e s p e c t i v e l y , w i t h 4 cm 3 a l f a l f a ( M e d i c a g o s a t i v a ) h a y c u b e s c o m p r i s i n g t h e b a l a n c e . The c h e m i c a l a n a l y s e s f o r PROTEC S a n d PROTEC R a r e shown i n T a b l e 2. T h e s e a n a l y s e s were c o n d u c t e d by t h e s u p p l i e r o f t h e p r o t e c t e d t a l l o w s u p p l e m e n t s , A l t a L i p i d s C a n a d a L t d . . T h e i n g r e d i e n t c o m p o s i t i o n s o f t h e t r e a t m e n t c o n c e n t r a t e s , on a d r y m a t t e r b a s i s a r e p r e s e n t e d i n T a b l e 3. R a t i o n s were f o r m u l a t e d 'The p r o t e c t e d t a l l o w s u p p l m e n t s w e r e d o n a t e d by A l t a L i p i d s C a n a d a L t d . , B a r r h e a d , A l b e r t a . 53 T A B L E 2. PROTECTED TALLOW COMPOSITIONS (DRY MATTER B A S I S ) PERIOD I PROTEC S PROTEC R COMPONENT SUPPLEMENT SUPPLEMENT C r u d e F a t (%) 38.0 43.8 C r u d e P r o t e i n (%) 25.0 26.0 I n v i t r o % P r o t e c t i o n 91 81 t o be i s o n i t r o g e n o u s a n d t o meet N a t i o n a l R e s e a r c h C o u n c i l r e q u i r e m e n t s ( 1 9 7 8 ) f o r e n e r g y , p r o t e i n , v i t a m i n s a n d m i n e r a l s , u s i n g c h e m i c a l a n a l y s e s p r o v i d e d by E a s t C h i l l i w a c k C o - o p f o r t h e b a r l e y , m i l l r u n , s o y b e a n m e a l a n d v i t a m i n - m i n e r a l p r e m i x , w h i c h t h e y s u p p l i e d . E s t i m a t e d v a l u e s f o r c h e m i c a l c o m p o n e n t s o f a l f a l f a h a y , m o l a s s e s a n d l i m e s t o n e w e r e o b t a i n e d f r o m t h e NAS-NRC A t l a s ( 1 9 7 1 ) . T h e minimum r e q u i r e m e n t o f 2 1 % a c i d -d e t e r g e n t f i b r e (ADF) c o u l d n o t be met w i t h r a t i o n s c o n t a i n i n g 70% c o n c e n t r a t e s u s e d i n t h i s s t u d y . C o n c e n t r a t e s w e r e m i x e d i n 180 kg q u a n t i t i e s i n a v e r t i c a l m i x e r f o r 20 m i n u t e s a n d b a g g e d . S a m p l e s w e r e t a k e n f r o m e a c h b a g o f a b a t c h a n d m i x e d t o g i v e o n e s a m p l e w h i c h was s t o r e d i n a p l a s t i c b a g f o r l a t e r a n a l y s i s . A l f a l f a h a y c u b e s were s a m p l e d m o n t h l y f o r a n a l y s i s . 54 T A B L E 3. CONCENTRATE COMPOSITIONS (DRY MATTER B A S I S ) PERIOD I CONCENTRATE INGREDIENT CONTROL PROTEC S PROTEC R % B a r l e y 63.88 58.48 57.94 M i l l Run 25.00 25.00 25.00 S o y b e a n M e a l 6.86 4.27 4.80 PROTEC S ® 0.00 8.00 0.00 PROTEC R ® 0.00 0.00 8.00 L i m e s t o n e 1 .00 1 .00 1 .00 V i t a m i n - M i n e r a l P r e m i x 1 1 .00 1 .00 1 .00 S a l t 0.50 0.50 0.50 D a i r y L u r e 0.01 0.01 0.01 M o l a s s e s 1 .75 1 .75 1 .75 TOTAL 100.00 100.00 100.00 ' C o n t a i n e d p e r k i l o g r a m : Mg 5 4 . 1 g ; F e 2 0 . 1 ; Zn 19.3g; Mn 4.1g; Cu 2.5g; S 2.5g; I 992mg; Co 33mg; V i t E 349 I U ; V i t A 1,047,185 I U ; V i t D 3 352,736 I U . i i . P e r i o d I I - P o s t - t r e a t m e n t P e r i o d ( w e e k s 16-20) A t a p p r o x i m a t e l y t h e 1 6 t h week o f l a c t a t i o n cows w e r e a b r u p t l y s w i t c h e d t o a p u r c h a s e d d a i r y c o n c e n t r a t e , w h i c h c o m p r i s e d 7 0 % o f t h e r a t i o n . T h e r e m a i n i n g 30% was p r o v i d e d by a l f a l f a h a y c u b e s . T h i s r a t i o n was m a i n t a i n e d t h r o u g h week 20 o f l a c t a t i o n . T h e c h e m i c a l a n a l y s e s o f t h e c o n c e n t r a t e u s e d d u r i n g t h i s p e r i o d were a s f o l l o w s : 18.0 M J / k g g r o s s e n e r g y ( G . E . ) , 16.4 % c r u d e p r o t e i n ( C P . ) , 3.1 % e t h e r e x t r a c t ( E . E . ) , 10.5 % a c i d - d e t e r g e n t f i b r e ( A D F ) , 6.4 % t o t a l a s h , .91 % 55 c a l c i u m ( C a ) , .61 % p h o s p h o r u s (P) a n d .35 % m a g n e s i u m ( M g ) . i i i . G e n e r a l M a i n t e n a n c e a n d S a m p l e C o l l e c t i o n • Cows on t r i a l w ere h o u s e d w i t h t h e b a l a n c e o f t h e m i l k i n g h e r d , i n a n a r e a w i t h a c c e s s t o a n o u t s i d e e x e r c i s e y a r d , f r e e s t a l l s a n d a bank o f e l e c t r o n i c a l l y c o n t r o l l e d i n d i v i d u a l f e e d e r s , w i t h C a l a n B r o a d b e n t d o o r s . Cows we r e f e d a t 0230 h o u r s a n d 1300 h o u r s ( b e f o r e m i l k i n g ) u n t i l A u g u s t 15, 1979 a n d t h e r e a f t e r a t 0700 a n d 1700 h o u r s ( a f t e r m i l k i n g ) . The c h a n g e i n f e e d i n g t i m e s was a g e n e r a l h e r d management d e c i s i o n u n r e l a t e d t o t h e t r i a l . I n p e r i o d s I a n d I I , c o n c e n t r a t e s a n d a l f a l f a c u b e s were k e p t s e p a r a t e by f i t t i n g t h e f e e d t u b s w i t h wooden d i v i d e r s . C o n c e n t r a t e s a n d c u b e s f o r e a c h cow f o r e a c h f e e d i n g were w e i g h e d i n t o s e p a r a t e b u c k e t s . F e e d i n t a k e s w e r e e s s e n t i a l l y a d l i b i t u m d u r i n g t h e s e p e r i o d s a n d t o a c h i e v e t h i s , w h i l e m a i n t a i n i n g a c o n s t a n t r a t i o o f c o n c e n t r a t e t o c u b e i n t a k e s , t h e amount o f f e e d o f f e r e d was s u c h t h a t i t was j u s t c o n s u m e d by t h e n e x t f e e d i n g . S m a l l p r e w e i g h e d b a g s o f e x t r a c o n c e n t r a t e a n d e x t r a c u b e s , i n t h e c o r r e c t p r o p o r t i o n s , w e r e f e d w h e n e v e r b o t h t h e g r a i n a n d f o r a g e h a d b e e n c l e a n e d u p . Cows h a d f r e e a c c e s s t o w a t e r a n d c o b a l t - i o d i z e d s a l t b l o c k s . T h r o u g h o u t t h e t r i a l , f e e d o f f e r e d was r e c o r d e d t w i c e d a i l y . F e e d i n g l e v e l s w e r e r e v i e w e d e v e r y s e c o n d d a y a n d w e i g h b a c k s o f c o n c e n t r a t e s a n d c u b e s w e r e m e a s u r e d s e p a r a t e l y , a s r e q u i r e d . Cows w e r e m i l k e d a t 0400 a n d 1430 h o u r s i n a m i l k i n g 56 p a r l o u r w i t h a n i n - l i n e , 3 - s t a l l , h i g h - l i n e s y s t e m . M i l k w e i g h t s were r e c o r d e d a t e v e r y m i l k i n g . M i l k s a m p l e s were t a k e n f o r e a c h cow, a p p r o x i m a t e l y e v e r y 2 weeks f r o m 2 c o n s e c u t i v e m i l k i n g s . S a m p l e s w e r e c o l l e c t e d f r o m t h e m i l k w e i g h j a r a f t e r a g g i t a t i o n a n d s t o r e d i n p l a s t i c b o t t l e s u s i n g p o t a s s i u m d i c h r o m a t e a s t h e p r e s e r v a t i v e . S a m p l e s were h e l d a t 4 - 1 0 ° C u n t i l t h e y were t r a n s p o r t e d t o t h e P r o v i n c i a l G o v e r n m e n t D a i r y L a b o r a t o r y f o r a n a l y s i s a s d e s c r i b e d i n s e c t i o n I I I . A . 2 . a on C h e m i c a l A n a l y s i s . B ody w e i g h t s w e r e m e a s u r e d , f o r e a c h cow, e v e r y 4 w e e k s , a f t e r t h e p.m. m i l k i n g on 2 c o n s e c u t i v e d a y s d u r i n g p e r i o d I . Due t o p r o b l e m s w i t h t h e e l e c t r o n i c s c a l e , a p o r t a b l e s c a l e was u s e d f o r b o d y w e i g h t m e a s u r e m e n t s t a k e n p r i o r t o J u n e , 1979 a n d t h e r e a f t e r a new e l e c t r o n i c s c a l e was u s e d . B o t h s c a l e s w e r e c a l i b r a t e d w i t h w e i g h t s r a n g i n g f r o m 400-675 k g , i n 25 kg i n c r e m e n t s . R e g r e s s i o n l i n e s f o r e a c h s c a l e , u s e d t o c a l c u l a t e a c t u a l b o d y w e i g h t s , a r e shown i n e q u a t i o n (1) f o r t h e p o r t a b l e s c a l e a n d i n e q u a t i o n (2) f o r t h e e l e c t r o n i c s c a l e . E q u a t i o n ( 1 ) : y= .970x + 26.979 r= .99 E q u a t i o n ( 2 ) : y= .988x - 39.221 r= .99 w h e r e : y= a c t u a l w e i g h t x= w e i g h t r e a d o f f t h e s c a l e B l o o d s a m p l e s , o b t a i n e d t h r o u g h j u g u l a r v e n i p u n c t u r e , w e r e t a k e n a p p r o x i m a t e l y e v e r y 4 weeks f o r e a c h cow. T w e n t y ml s a m p l e s were d r a w n i n t o h e p a r i n i z e d , V a c u t a i n e r ® , b l o o d c o l l e c t i o n t u b e s , s t o r e d a t 4 - 1 0 o C f o r up t o 1 h o u r , a n d w e r e 57 t h e n c e n t r i f u g e d ( 1 , 0 0 0 x g ) f o r 10 m i n u t e s ( 2 5 ° C ) . P l a s m a d r a w n o f f was s t o r e d a t - 2 0 ° C p r i o r t o a n a l y s i s . Rumen f l u i d was s a m p l e d by s t o m a c h t u b e f r o m 5 a n i m a l s a t t h e e n d o f p e r i o d I (1 on t h e c o n t r o l , 2 on t h e PROTEC S, a n d 2 on t h e PROTEC R t r e a t m e n t s ) . T h e rumen f l u i d was s t r a i n e d t h r o u g h 4 l a y e r s o f c h e e s e c l o t h a n d d e p r o t e i n i z e d by t h e a d d i t i o n o f 1 2 % ( v / v ) o f 10% Z n S O „ f o l l o w e d by 1 2 % ( v / v ) o f 0.5N NaOH w h i l e s h a k i n g . The d e p r o t e i n i z e d rumen f l u i d was h e l d a t 2 5 ° C f o r a p p r o x i m a t e l y 1 h o u r . S a m p l e s were c e n t r i f u g e d f o r 10 m i n u t e s a t 1,000xg a n d t h e s u p e r n a t a n t was d e c a n t e d a n d s t o r e d a t - 2 0 ° C . c . D i g e s t i b i l i t y T r i a l s B e t w e e n t h e 1 2 t h a n d 1 6 t h w e e k s o f l a c t a t i o n , 4 c o ws p e r t r e a t m e n t w e r e e a c h i n v o l v e d i n a d i g e s t i b i l i t y t r i a l w i t h a 7-d a y c o l l e c t i o n p e r i o d . T h r e e s e p a r a t e d i g e s t i b i l i t y t r i a l s w ere c o n d u c t e d a t o n e - m o n t h i n t e r v a l s b e c a u s e a l l 12 cows w e r e n o t i n t h e i r 1 2 t h - 1 6 t h w eeks o f l a c t a t i o n a t t h e same t i m e a s a r e s u l t o f t h e f a c t t h a t cows s t a r t e d on t r i a l when t h e y c a l v e d . Cows w e r e moved t o t h e d i g e s t i b i l i t y t r i a l a r e a a n d p u t i n s t a l l s on a F r i d a y a n d t h e d i g e s t i b i l i t y t r i a l c o l l e c t i o n commenced on t h e f o l l o w i n g Monday a t 1200 h o u r s . T h e p r e -c o l l e c t i o n p e r i o d a l l o w e d t h e cows t o s t a b i l i z e t h e i r f e e d i n t a k e s a t a new l e v e l a s s o c i a t e d w i t h t h e r e d u c e d l e v e l o f e x e r c i s e a n d t o become a c c u s t o m e d t o t h e new e n v i r o n m e n t . P r i o r t o t h e c o l l e c t i o n p e r i o d t h e b e d d i n g was r e m o v e d f r o m t h e s t a l l s a n d t h e r u b b e r m a t s i n e a c h w e r e w a s h e d . No b e d d i n g 58 m a t e r i a l was u s e d d u r i n g t h e c o l l e c t i o n p e r i o d . Cows w e r e f i t t e d w i t h r u b b e r h o s e s f o r u r i n e c o l l e c t i o n . T h i s i n v o l v e d f a s t e n i n g a m e t a l r i n g i n s i d e one e n d o f t h e h o s e w i t h g l u e , a n d s h a p i n g i t t o f i t o v e r t h e v u l v a . The r i n g s e r v e d t o h o l d t h e h o s e o p e n a n d t h e r i n g e n d o f t h e h o s e was . p o s i t i o n e d b y means o f s t r i n g s t i e d t o p l a s t i c m e s h e s . T h e m e s h e s w e r e g l u e d p r o x i m a l , d i s t a l , a n d v e n t r a l t o t h e d o r s a l a n d l a t e r a l t u b e r s a c r a l e . T h e o t h e r e n d o f t h e h o s e was a t t a c h e d t o a c o v e r e d , s t a i n l e s s s t e e l r e c e p t a c l e . U r i n e was c o l l e c t e d u n d e r a m o n o l a y e r o f t o l u e n e t o p r e v e n t a n y e v a p o r a t i v e l o s s e s . T w e n t y - f o u r h o u r u r i n e o u t p u t s w e r e w e i g h e d a n d m i x e d a n d 500 ml w e r e f r o z e n a t - 2 0 ° C f o r s u b s e q u e n t a n a l y s i s . F a e c e s c o l l e c t i o n b o x e s w e r e p l a c e d b e h i n d e a c h cow. F a e c e s was s h o v e l l e d i n t o a p l a s t i c b a g - l i n e d r u b b e r g a r b a g e t u b a s s o o n a s p o s s i b l e a f t e r i t h a d b e e n v o i d e d a n d t h e l i d was k e p t on t o p r e v e n t m o i s t u r e l o s s e s . T w e n t y - f o u r h o u r f a e c a l o u t p u t s w e r e w e i g h e d a n d t h e t o t a l c o l l e c t i o n was m i x e d a n d s a m p l e d f o r d r y m a t t e r d e t e r m i n a t i o n s on a d a i l y b a s i s . A g r a b s a m p l e o f f a e c e s was t a k e n f o r e a c h 24 h o u r p e r i o d a n d s t o r e d i n a p l a s t i c b a g a t - 2 0 ° C . S a m p l e s were l a t e r c o m p o s i t e d f o r c h e m i c a l a n a l y s i s . F e e d o f f e r e d was r e c o r d e d t w i c e d a i l y a n d c o n c e n t r a t e a n d c u b e w e i g h b a c k s w e r e r e c o r d e d d a i l y . G r a i n a n d c u b e s o f f e r e d a n d r e f u s e d w e r e s a m p l e d d a i l y a n d c o m p o s i t e d p r i o r t o c h e m i c a l a n a l y s e s . Cows we r e k e p t i n t h e s t a l l s f o r t h e e n t i r e 7 - day 59 c o l l e c t i o n p e r i o d a n d we r e m i l k e d u s i n g a p o r t a b l e m i l k i n g m a c h i n e , a t , 0 5 0 0 a n d 1600 h o u r s . 2. C h e m i c a l A n a l y s i s a . M i l k M i l k s a m p l e s w e r e s e n t t o t h e P r o v i n c i a l G o v e r n m e n t D a i r y L a b o r a t o r y a n d we r e a n a l y z e d by an i n f r a - r e d m i l k a n a l y z e r (IRMA) f o r f a t , p r o t e i n a n d l a c t o s e p e r c e n t a g e s . M i l k s a m p l e s i n 8 d i f f e r e n t f a t t e s t r a n g e s w e r e u s e d t o c a l i b r a t e t h e IRMA, b a s e d on t h e i r a n a l y s i s . M i l k f a t , m i l k p r o t e i n a n d m i l k l a c t o s e w e r e d e t e r m i n e d by t h e M o j o n n i e r t e s t , t h e K j e l d a h l m e t h o d a n d P o l a r i m e t r y , r e s p e c t i v e l y . F a t - c o r r e c t e d m i l k a n d s o l i d s - c o r r e c t e d m i l k v a l u e s w e r e c o m p u t e d a c c o r d i n g t o t h e f o r m u l a e o f G a i n e s ( 1 9 2 8 ) a n d T y r r e l l a n d R e i d ( 1 9 6 5 ) , r e s p e c t i v e l y . b . F e e d s t u f f s , F a e c e s , U r i n e S a m p l e s o f c o n c e n t r a t e s , c u b e s , f e e d w e i g h b a c k s a n d f a e c e s f o r a n a l y s i s w e r e g r o u n d t o p a s s a o n e m i l l i m e t e r mesh s i e v e , u s i n g a s i z e 8 i n c h C h r i s t y a n d N o r r i s hammer m i l l . Where n e c e s s a r y , s a m p l e s w e r e f i r s t t h a w e d a n d d r i e d t o c o n s t a n t w e i g h t i n a f o r c e d - d r a u g h t o v e n a t 6 0 ° C a n d d r y m a t t e r d e t e r m i n a t i o n s were made u n d e r t h e s e c o n d i t i o n s . S u b - s a m p l e s o f t h e g r o u n d s a m p l e s w e r e s t o r e d i n W h i r l - p a k ® b a g s . U r i n e s a m p l e s were t h a w e d a n d f i l t e r e d p r i o r t o a n a l y s i s . C o n c e n t r a t e s a n d a l f a l f a h a y c u b e s o f f e r e d a n d r e f u s e d , a n d 60 f a e c a l g r a b s a m p l e s were a n a l y z e d f o r : D.M., G.E., E . E . , N, ADF, t o t a l a s h , C a , P, a n d Mg. U r i n e was a n a l y z e d f o r N. I t was i n t e n d e d t h a t s p e c i f i c g r a v i t y w o u l d be d e t e r m i n e d f o r t h e u r i n e s a m p l e s . H o w e v e r , t h i s was p r e v e n t e d due t o a power f a i l u r e t o t h e f r e e z e r , c a u s i n g w a t e r t o be i n t r o d u c e d i n t o some o f t h e u r i n e s a m p l e s . T h e r e f o r e a l i t e r a t u r e v a l u e o f 1.030 was u s e d f o r t h e s p e c i f i c g r a v i t y o f u r i n e ( F e d e r a t i o n o f A m e r i c a n S o c i e t i e s f o r E x p e r i m e n t a l B i o l o g y , 1 9 6 8 ) . i . D r y M a t t e r T r i p l i c a t e D.M. d e t e r m i n a t i o n s were d o n e by d r y i n g s a m p l e s t o a c o n s t a n t w e i g h t a t 1 0 5 ° C i n a f o r c e d - d r a u g h t o v e n . i i . C o m b u s t i b l e E n e r g y C o m b u s t i b l e e n e r g y o r G.E. d e t e r m i n a t i o n s w e r e c a r r i e d o u t i n d u p l i c a t e u s i n g t h e m e t h o d o u t l i n e d i n t h e G a l l e n k a m p A u t o b o m b A u t o m a t i c A d i a b a t i c Bomb C a l o r i m e t e r T e c h n i c a l M a n u a l . 61 i i i . E t h e r E x t r a c t E t h e r e x t r a c t i o n s w e r e p e r f o r m e d on d u p l i c a t e s a m p l e s u s i n g t h e m e t h o d d e s c r i b e d i n t h e L a b c o n c o G o l d f i s c h F a t E x t r a c t i o n M a n u a l . T h e s o l v e n t u s e d was a n h y d r o u s e t h y l e t h e r . i v . Wet O x i d a t i o n T h e wet o x i d a t i o n p r o c e d u r e f o r b i o l o g i c a l m a t e r i a l , o f P a r k i n s o n a n d A l l e n ( 1 9 7 5 ) was u s e d t o p r e p a r e s a m p l e s f o r n i t r o g e n a n d m i n e r a l a n a l y s e s . v . N i t r o g e n S a m p l e s p r e p a r e d a s i n ( i v ) w e r e a n a l y z e d i n d u p l i c a t e on a T e c h n i c o n a u t o a n a l y z e r I I ( I n d u s t r i a l m e t h o d number 321-74A) f o r A m m o n i a c a l N i t r o g e n , w h i c h e m p l o y e d a c o l o u r i m e t e r f o r d e t e c t i o n . v i . A c i d D e t e r g e n t F i b r e D u p l i c a t e s a m p l e s w e r e a n a l y z e d f o r ADF a c c o r d i n g t o t h e m e t h o d o f W a l d e r n ( 1 9 7 1 ) . 62 v i i . A s h ( T o t a l ) A s h d e t e r m i n a t i o n s w e r e d o n e i n t r i p l i c a t e by h e a t i n g t h e c h a r r e d s a m p l e s a t 4 5 0 ° C o v e r n i g h t a s o u t l i n e d i n a m a n u a l o f a n a l y t i c a l m e t h o d s ( M i n i s t r y o f A g r i c u l t u r e , F i s h e r i e s a n d F o o d . L o n d o n . 1 9 7 3 ) . v i i i . C a l c i u m S a m p l e s p r e p a r e d a s i n ( i v ) w e r e a n a l y z e d u s i n g a P e r k i n E l m e r 560 a t o m i c a b s o r p t i o n s p e c t r o p h o t o m e t e r w i t h a h o l l o w c a t h o d e l a m p a n d a n a i r / a c e t y l e n e f l a m e . S a m p l e s w e r e r e a d o v e r t h e r a n g e o f 0-15 i/g/ml. S t a n d a r d s were p r e p a r e d u s i n g L a C l 3 a s a r e l e a s i n g a g e n t . i x . P h o s p h o r u s S a m p l e s p r e p a r e d a s i n ( i v ) w e r e a n a l y z e d i n d u p l i c a t e on t h e T e c h n i c o n a u t o a n a l y z e r I I f o r P u s i n g a m o l y b d o p h o s p h o v a n a d a t e m e t h o d ( I n d u s t r i a l m e t h o d number 327-74W) . 63 x. M a g n e s i u m S a m p l e s a s p r e p a r e d i n ( i v ) w e r e a n a l y z e d u s i n g a P e r k i n E l m e r 560 a t o m i c a b s o r p t i o n s p e c t r o p h o t o m e t e r , h o l l o w c a t h o d e l a m p a n d a i r / a c e t y l e n e f l a m e . S a m p l e s were r e a d o v e r t h e r a n g e o f 0-3 n g / m l . c . Rumen V o l a t i l e F a t t y A c i d s i . P r e p a r a t i o n F i v e ml s a m p l e s o f d e p r o t e i n i z e d rumen f l u i d w e r e m i x e d w i t h 1 g M g S O « a n d 0.1 ml o f 8 5 % o r t h o p h o s p h o r i c a c i d a n d d i s t i l l e d i n a Markham s t i l l . C o l l e c t i o n o f 150 ml o f d i s t i l l a t e a s s u r e d c o m p l e t e s a m p l e VFA d i s t i l l a t i o n ( R o s s a n d K i t t s , 1 9 7 1 ) . A l i q u o t s o f t h e d i s t i l l a t e w ere t i t r a t e d u n d e r a n a t m o s p h e r e o f n i t r o g e n w i t h 0.002N NaOH, u s i n g p h e n o l p h t h a l e i n a s a n i n d i c a t o r a n d t o t a l meq o f VFA were c a l c u l a t e d . T h e r e m a i n i n g d i s t i l l a t e was b a s i f i e d w i t h 1.ON NaOH a n d e v a p o r a t e d t o d r y n e s s i n a n o v e n a t 6 0 ° C . The VFA s o d i u m s a l t s w e r e q u a n t i t a t i v e l y t r a n s f e r r e d t o a 5 m l b e a k e r w h i c h was c o n n e c t e d t o a m i c r o d i s t i l l a t i o n a p p a r a t u s ( F i g . 8 ) . T h e l a t t e r was a m o d i f i c a t i o n o f t h a t d e s c r i b e d by R o s s a n d K i t t s ( 1 9 7 1 ) a n d i n c l u d e d a p y r e x f u n n e l w h i c h f a c i l i t a t e d t h e r e c o v e r y o f t h e c o n d e n s e d d r o p l e t s . T h e s a m p l e was g e n t l y h e a t e d a n d 4 c o n d e n s e d d r o p l e t s w e r e c o l l e c t e d i n t o t h e f u n n e l . T h e t o t a l s a m p l e was d r a w n u p i n t o a 50 * i l c a p i l l a r y t u b e a n d s e a l e d w i t h p l a s t i c i n e . S a m p l e s were s t o r e d a t 4 - 1 0 ° C f o r l a t e r g a s l i q u i d 64 * Ht0 gnirif ?ovt foY Capillary Tube CafttlaYif Tube 5« Us Heai Source F i g u r e 8. M i c r o d i s t i l l a t i o n a p p a r a t u s : M o d i f i c a t i o n o f t h a t u s e d by R o s s a n d K i t t s , ( 1 9 7 1 ) . 65 c h r o m a t o g r a p h i c a n a l y s i s . i i . Gas L i q u i d C h r o m a t o g r a p h y ( G . L . C . ) T h e VFA s a m p l e s w e r e a n a l y z e d by G . L . C . A c a p i l l a r y t u b e was b r o k e n o p e n a t one e n d a n d a H a m i l t o n 1.0 »il s y r i n g e ( 7 , 0 0 0 s e r i e s ) was u s e d t o draw up 0.5-1.0 al o f s a m p l e . T h e s a m p l e was a n a l y z e d on a g a s c h r o m a t o g r a p h ( M i c r o t e k 220) u n d e r t h e f o l l o w i n g c o n d i t i o n s : 10% AT 1 2 0 0 / 1 % H 3 P O « on 80/100 C h r o m o s o r b W AW; 2m x 4mm ID g l a s s ; i n l e t ( 1 8 5 ° C ) , o v e n ( l 3 5 ° C ) , d e t e c t o r ( 1 9 0 ° C ) ; f l o w r a t e = 50 m l / m i n . N, 30 m l / m i n . H y d r o g e n , 247 m l / m i n . A i r ; d e t e c t o r = f l a m e i o n i z a t i o n ; a n d s a m p l e s i z e = 0.5 M1. d . B l o o d P l a s m a i . G l u c o s e G l u c o s e d e t e r m i n a t i o n s w e r e d o n e i n d u p l i c a t e on p l a s m a s a m p l e s u s i n g a n e n z y m a t i c , c o l o u r i m e t r i c d e t e r m i n a t i o n ( S i g m a k i t #510) , b a s e d on t h e f o l l o w i n g c o u p l e d e n z y m a t i c r e a c t i o n s : G l u c o s e O x i d a s e 1. G l u c o s e + 2 H 2 0 + 0 2 > G l u c o n i c A c i d + 2 H 2 0 2 P e r o x i d a s e 2. H 2 0 2 + o - D i a n i s i d i n e > O x i d i z e d o - D i a n i s i d i n e ( c o l o u r l e s s ) ( b r o w n ) S a m p l e s were r e a d a t 450 nm on a G i l f o r d ® S t a s a r I I s p e c t r o p h o t o m e t e r . 66 i i . N o n - E s t e r i f i e d F a t t y A c i d s P l a s m a n o n - e s t e r i f i e d f a t t y a c i d s (NEFA) w e r e a n a l y z e d i n d u p l i c a t e a c c o r d i n g t o t h e c o l o u r i m e t r i c m e t h o d o f Duncombe ( 1 9 6 4 ) . P a l m i t i c a c i d was u s e d a s t h e s t a n d a r d a n d s a m p l e s were r e a d on a U n i c a m SP-800B s p e c t r o p h o t o m e t e r a t 440 nm. 3. S t a t i s t i c a l A n a l y s i s Two l e a s t - s q u a r e s m o d e l s w e r e u s e d t o a n a l y z e t h e d a t a . T h e f i r s t s t a t i s t i c a l l i n e a r m o d e l ( E q u a t i o n 3) was d e s i g n e d t o m e a s u r e t h e e f f e c t s o f t r e a t m e n t , b r e e d a n d l a c t a t i o n c a t e g o r y ( f i r s t l a c t a t i o n v e r s u s ^ 2nd l a c t a t i o n ) on i n t a k e , p r o d u c t i o n , e f f i c i e n c y o f p r o d u c t i o n , A.D.G. a n d b l o o d m e t a b o l i t e s . Y i j k l = » + T i + B j + Lk + T B i j + T L i k + B L j k + T B L i j k + a D i j k l + e i j k l ( E q . 3) w h e r e : it = t h e o v e r a l l p o p u l a t i o n mean T i = t h e e f f e c t o f t h e i - t h t r e a t m e n t B j = t h e e f f e c t o f t h e j - t h b r e e d Lk = t h e e f f e c t o f t h e k - t h l a c t a t i o n c a t e g o r y T B i j = t h e e f f e c t o f t h e i - t h t r e a t m e n t s p e c i f i c t o t h e j - t h b r e e d T L i k = t h e e f f e c t o f t h e i - t h t r e a t m e n t s p e c i f i c t o t h e k - t h l a c t a t i o n c a t e g o r y B L j k = t h e e f f e c t o f t h e j - t h b r e e d s p e c i f i c t o t h e k - t h l a c t a t i o n c a t e g o r y T B L i j k = t h e e f f e c t o f t h e i - t h t r e a t m e n t s p e c i f i c t o t h e j - t h b r e e d on t h e k - t h l a c t a t i o n c a t e g o r y 67 D i j k l = t h e c o v a r i a b l e d a y s on t r e a t m e n t a = t h e c o e f f i c i e n t a s s o c i a t e d w i t h D i j k l e i j k l = t h e r a n d o m e r r o r a s s o c i a t e d w i t h e a c h cow Y i j k l r e p r e s e n t s t h e m e a s u r e m e n t o f t h e 1 - t h i n d i v i d u a l i n t h e k - t h l a c t a t i o n c a t e g o r y ( L ) o f t h e j - t h b r e e d (B) on t h e i -t h t r e a t m e n t ( T ) . I t was c o n s i d e r e d d e s i r a b l e t o e x a m i n e b r e e d a s a m a i n e f f e c t b e c a u s e i t h a s b e e n d e m o n s t r a t e d t h a t d i f f e r e n t b r e e d s r e s p o n d d i f f e r e n t l y t o p r o t e c t e d l i p i d s u p p l e m e n t a t i o n o f t h e d i e t . C ook a n d S c o t t ( 1 9 7 2 ) r e p o r t e d t h a t when f e e d i n g f o r m a l d e h y d e - t r e a t e d c a s e i n - s a f f l o w e r o i l (1:1,w/w) t o J e r s e y , S a h i w a l a n d J e r s e y X S a h i w a l c r o s s b r e d c o w s , a p p r o x i m a t e l y 40% o f t h e C18:2 p r e s e n t i n t h e s u p p l e m e n t was t r a n s f e r r e d i n t o t h e m i l k o f t h e J e r s e y a n d c r o s s b r e d a n i m a l s . I n c o n t r a s t , o n l y 8% o f t h e C18:2 was t r a n s f e r r e d i n t o t h e m i l k o f t h e S a h i w a l s , i n d i c a t i n g a b r e e d d i f f e r e n c e w i t h r e s p e c t t o t h e r e s p o n s e t o p r o t e c t e d l i p i d s . P a l m q u i s t a n d C o n r a d ( 1 9 7 8 ) on o b s e r v i n g d i f f e r e n t r e s p o n s e s by J e r s e y s o r H o l s t e i n s t o u n p r o t e c t e d h y d r o l y z e d b l e n d e d f a t i n t h e d i e t , s u g g e s t e d t h a t t h e c a p a c i t y o f t h e rumen may be more l i m i t i n g f o r e n e r g y i n t a k e i n r e l a t i o n t o p r o d u c t i o n o f m i l k e n e r g y i n t h e s m a l l e r b r e e d . L a c t a t i o n c a t e g o r y was a l s o c o n s i d e r e d a s a m a i n e f f e c t . Cows were g r o u p e d i n t o f i r s t c a l f - h e i f e r s a n d ^ 2nd l a c t a t i o n c o w s . I t h a s b e e n shown t h a t m i l k y i e l d i n c r e a s e s w i t h a g e a t a n e v e r - d e c l i n i n g r a t e u n t i l t h e cow r e a c h e s m a t u r i t y . T h e i n c r e a s e i n m i l k y i e l d f r o m f i r s t l a c t a t i o n t o m a t u r e a g e i s i n t h e o r d e r o f 1 4-30% ( G a c u l a e t a l . , 1 9 6 5 ) . T h e s e c o n d s t a t i s t i c a l l i n e a r m o d e l ( E q u a t i o n 4) was 68 d e s i g n e d t o m e a s u r e t h e e f f e c t s o f t r e a t m e n t a n d l a c t a t i o n c a t e g o r y on a p p a r e n t d i g e s t i b i l i t i e s o f D.M., o r g a n i c m a t t e r (O.M.), N, G.E., E . E . , ADF, C a , P, Mg a n d t o t a l a s h . Y i j k = v + T i + L j + T L i j + a D i j k + e i j k ( E q . 4) w h e r e : » = t h e o v e r a l l p o p u l a t i o n mean T i = t h e e f f e c t o f t h e i - t h t r e a t m e n t L j = t h e e f f e c t o f t h e j - t h l a c t a t i o n c a t e g o r y T L i j = t h e e f f e c t o f t h e i - t h t r e a t m e n t s p e c i f i c t o t h e j - t h l a c t a t i o n c a t e g o r y a D i j k = t h e c o v a r i a b l e d a y s i n p e r i o d I I a = t h e c o e f f i c i e n t a s s o c i a t e d w i t h D i j k c i j k = t h e r a n d om e r r o r a s s o c i a t e d w i t h e a c h cow Y i j k r e p r e s e n t s t h e m e a s u r e m e n t o f t h e k - t h i n d i v i d u a l i n t h e j - t h l a c t a t i o n c a t e g o r y ( L ) on t h e i - t h t r e a t m e n t ( T ) . Two a p r i o r i , o r t h o g o n a l , s i n g l e d e g r e e o f f r e e d o m c o n t r a s t s were c o n s i d e r e d f o r a l l d a t a : 1. T h e e f f e c t s o f t h e c o n t r o l t r e a t m e n t v e r s u s t h e c o m b i n e d e f f e c t s o f t h e p r o t e c t e d t a l l o w t r e a t m e n t s ( C v s . S + R ) , a n d s e c o n d l y 2. T h e e f f e c t s o f t h e s o y b e a n m e a l p r o t e c t e d t a l l o w t r e a t m e n t v e r s u s t h e e f f e c t s o f t h e c a n o l a m e a l p r o t e c t e d t a l l o w t r e a t m e n t (S v s . R ) . T h e r e s u l t s were e v a l u a t e d by a n a l y s i s o f v a r i a n c e ( S t e e l a n d T o r r i e , 1960) w h i c h was c o m p u t e d u s i n g t h e p a c k a g e d p r o g r a m : UBC BMD:10V. 69 B. R e s u l t s 1. P e r i o d I a . R a t i o n C h e m i c a l A n a l y s i s C h e m i c a l a n a l y s e s o f t h e t r e a t m e n t c o n c e n t r a t e s a n d t h e a l f a l f a h a y c u b e s a r e o u t l i n e d i n T a b l e 4. T h e G.E. c o n t e n t s T A B L E 4. CHEMICAL ANALYSIS OF F E E D S T U F F S {DRY MATTER B A S I S ) PERIOD I CONCENTRATE I T E M CONTROL PROTEC S PROTEC R A L F A L F A (MJ/KG) G r o s s E n e r g y 17.9 18.7 18.6 18.5 (%) C r u d e P r o t e i n 15.5 16.5 16.2 18.2 E t h e r E x t r a c t 2.3 4.8 5.6 1 .7 A c i d - D e t e r g e n t F i b r e 8.7 8.6 10.1 36.6 T o t a l A s h 5.6 5.9 5.7 9.2 C a l c ium .56 .70 .63 1 .76 P h o s p h o r u s .57 .60 .55 .27 M a g n e s i u m .35 .34 .35 .32 o f t h e c o n t r o l , PROTEC S a n d PROTEC R c o n c e n t r a t e s w e r e 17.9, 18.7 a n d 18.6 M J / k g , r e s p e c t i v e l y . T h i s r e p r e s e n t s an e n e r g y d e n s i t y o f 0.8 M J / k g more f o r t h e c o n c e n t r a t e s c o n t a i n i n g p r o t e c t e d t a l l o w , c o m p a r e d w i t h t h e c o n t r o l c o n c e n t r a t e , o r 70 e x p r e s s e d a s a % i t means t h e c o n c e n t r a t e s c o n t a i n i n g p r o t e c t e d t a l l o w c o n t a i n e d 4% more e n e r g y . T h e a v e r a g e % E . E . f o r t h e c o n c e n t r a t e s w i t h p r o t e c t e d t a l l o w ( a v e r a g e = 5.2 % E . E . ) was more t h a n t w i c e t h a t o f t h e c o n t r o l c o n c e n t r a t e ( 2 . 3 % E . E . ) . T h e PROTEC S c o n c e n t r a t e c o n t a i n e d 1.1 % l e s s E . E . t h a n t h e PROTEC R c o n c e n t r a t e . T h e c o m p l e t e c o n t r o l , PROTEC S a n d PROTEC R r a t i o n s ( 7 0 % c o n c e n t r a t e : 3 0 % a l f a l f a h a y c u b e s ) c o n t a i n e d 16.3, 17.0 a n d 16.8 % C P . , r e s p e c t i v e l y . P e r c e n t ADF was s i m i l a r f o r t h e c o n t r o l a n d PROTEC S c o n c e n t r a t e s , b u t was h i g h e r by 1.4 % f o r t h e PROTEC R c o n c e n t r a t e . A l l c o n c e n t r a t e s w e r e s i m i l a r i n c o m p o s i t i o n w i t h r e s p e c t t o t o t a l a s h , C a , P a n d Mg. The Ca:P r a t i o s o f t h e c o m p l e t e r a t i o n s , a s f e d , were 1.9:1, 2.0:1 a n d 2.1:1 f o r t h e c o n t r o l , PROTEC S a n d PROTEC R r a t i o n s , r e s p e c t i v e l y . b . I n t a k e s P r e d i c t e d means f o r d a i l y , p e r cow i n t a k e s o f f e e d s t u f f s , e n e r g y a n d p r o t e i n , w i t h t h e c o r r e s p o n d i n g s t a n d a r d e r r o r s , a r e o u t l i n e d i n T a b l e 5. C o n c e n t r a t e s a n d c u b e s were o f f e r e d i n t h e r a t i o o f 70:30 ( a i r d r y b a s i s ) a n d w e r e c o n s u m e d ( d r y m a t t e r b a s i s ) i n t h e r a t i o s : 6 9 : 3 1 , 6 9 : 3 1 , a n d 68:32 f o r t h e c o n t r o l , PROTEC S a n d PROTEC R t r e a t m e n t s , r e s p e c t i v e l y ( T a b l e 5 ) . The p r e d i c t e d mean d a i l y i n t a k e s p e r cow o f c o n c e n t r a t e s , T A B L E 5. PREDICTED MEAN D A I L Y INTAKES PER COW (DRY MATTER B A S I S ) PERIOD I I T E M TREATMENT ORTHOGONAL CONTRAST (C) (S) V S . V S . PROTEC S PROTEC R (S+R) (R) CONTROL F e e d I n t a k e ( k g / c o w / d a y ) C o n c e n t r a t e S . E . 1 12.12 .554 12.24 .483 1 1 .45 .605 NS NS A l f a l f a C u b e s S.E. 5.46 .209 5.49 .180 5.46 .259 NS NS T o t a l D.M. S.E. 17.59 .751 17.73 .655 16.91 .862 NS NS E n e r g y I n t a k e ( M J / c o w / d a y ) C o n c e n t r a t e G.E. 216.6 228.4 212.7 NS NS S . E . 9.88 9.04 11.27 A l f a l f a G.E. 101.2 101.6 101.2 NS NS S . E . 3.88 3.35 4.81 T o t a l G.E. 317.7 330.0 313.8 NS NS S . E . 13.55 12.23 16.01 T o t a l D.E. 222.0 232.3 221.3 NS NS S . E . 9.46 8.61 11.29 P r o t e i n I n t a k e ( k g / c o w / d a y ) C o n c e n t r a t e C P . 1.87 2.02 1.82 NS NS S . E . .088 .087 .101 A l f a l f a C P . .99 1.00 1.00 NS NS S . E . .036 .037 .051 T o t a l C P . 2.86 3.01 2.82 NS NS S . E . .121 .123 .151 T o t a l D.P. 2.17 2.20 2.10 NS NS S . E . .092 .090 .113 ' S . E . : S t a n d a r d E r r o r NS: n o t s i g n i f i c a n t 72 c u b e s a n d t o t a l d r y m a t t e r , w e r e 12.12, 4.36 a n d 17.59 kg f o r t h e c o n t r o l r a t i o n , 12.24, 5.49 a n d 17.73 kg f o r t h e PROTEC S r a t i o n , a n d 11.45, 5.46, a n d 16.91 kg f o r t h e PROTEC R r a t i o n , r e s p e c t i v e l y . T h e a n a l y s i s o f v a r i a n c e i n d i c a t e d t h e r e w e r e no s i g n i f i c a n t d i f f e r e n c e s (P > .05) e i t h e r b e t w e e n t h e c o n t r o l r a t i o n a n d t h e r a t i o n s c o n t a i n i n g p r o t e c t e d t a l l o w ( o r t h o g o n a l c o n t r a s t 1 ) , o r b e t w e e n t h e PROTEC S a n d PROTEC R r a t i o n s ( o r t h o g o n a l c o n t r a s t 2 ) , i n t e r m s o f t h e d a i l y i n t a k e s p e r cow o f c o n c e n t r a t e s , c u b e s o r d r y m a t t e r . T h e p r e d i c t e d means show t h a t c o m p a r e d w i t h t h e c o n t r o l r a t i o n t h e i n t a k e s o f c o n c e n t r a t e s a n d t o t a l d r y m a t t e r t e n d e d t o be h i g h e r on t h e PROTEC S r a t i o n a n d l o w e r on t h e PROTEC R r a t i o n , a l t h o u g h n o t s i g n i f i c a n t l y s o . T h e p r e d i c t e d mean d a i l y , p e r cow i n t a k e s o f c o n c e n t r a t e g r o s s e n e r g y , c u b e g r o s s e n e r g y , t o t a l g r o s s e n e r g y a n d t o t a l d i g e s t i b l e e n e r g y ( M J / d a y ) , w e r e 2 1 6 . 6 , 101.2, 3 1 7 . 7 , a n d 222.0 f o r t h e c o n t r o l r a t i o n , 2 2 8 . 4 , 101.6, 3 3 0 . 0 , a n d 232.3 f o r t h e PROTEC S r a t i o n a n d 2 1 2 . 7 , 101.2, 3 1 3 . 8 , a n d 221.3 M J / d a y f o r t h e PROTEC R r a t i o n , r e s p e c t i v e l y . No s i g n i f i c a n t d i f f e r e n c e s ( P > .05) were o b s e r v e d f o r r a t i o n s w i t h p r o t e c t e d t a l l o w v e r s u s t h a t w i t h o u t , o r b e t w e e n r a t i o n s w i t h d i f f e r e n t t y p e s o f p r o t e c t e d t a l l o w , f o r a n y g r o s s e n e r g y i n t a k e p a r a m e t e r . D i g e s t i b l e e n e r g y i n t a k e / c o w / d a y was c o m p a r a b l e on t h e c o n t r o l a n d PROTEC R r a t i o n s b u t t e n d e d t o be h i g h e r on t h e PROTEC S r a t i o n . P r e d i c t e d mean d a i l y , p e r cow i n t a k e s o f c o n c e n t r a t e c r u d e p r o t e i n , c u b e c r u d e p r o t e i n , t o t a l c r u d e p r o t e i n a n d t o t a l 73 d i g e s t i b l e p r o t e i n ( k g / d a y ) , w e r e 1.87, 0.99, 2.86 a n d 2.17 f o r t h e c o n t r o l r a t i o n , 2.02, 1.00, 3.01, a n d 2.20 f o r t h e PROTEC S r a t i o n , a n d 1.82, 1.00, 2.82 a n d 2.10 k g / d a y f o r t h e PROTEC R r a t i o n , r e s p e c t i v e l y . T h e r e w e r e no s i g n i f i c a n t d i f f e r e n c e s b e t w e e n t y p e s o f p r o t e c t e d t a l l o w s o r b e t w e e n t h e p r o t e c t e d t a l l o w s a n d t h e c o n t r o l g r o u p (P > . 0 5 ) , a l t h o u g h d i g e s t i b l e p r o t e i n i n t a k e t e n d e d t o be l o w e r on t h e PROTEC R r a t i o n . T h e 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 ( R 2 ) f o r t h e i n t a k e v a r i a b l e s o f T a b l e 5 a r e p r e s e n t e d i n T a b l e 6. T h e m o d e l f i t t e d t o t h e d a i l y i n t a k e s o f d r y m a t t e r , e n e r g y a n d p r o t e i n , a c c o u n t e d f o r more t h a n 67 % o f t h e v a r i a t i o n i n t h e d e p e n d e n t v a r i a b l e s . I n e v e r y c a s e t h e e f f e c t s o f b r e e d a n d l a c t a t i o n c a t e g o r y were s i g n i f i c a n t (P < . 0 1 ) , w i t h t h e H o l s t e i n s c o n s u m i n g more t h a n t h e A y r s h i r e s a n d t h e ^ 2nd l a c t a t i o n cows c o n s u m i n g more t h a n t h e h e i f e r s . A summary o f t h e p r e d i c t e d means a n d a s s o c i a t e d s t a n d a r d e r r o r s f o r s i g n i f i c a n t s o u r c e s o f v a r i a t i o n c a n be f o u n d i n T a b l e I o f t h e A p p e n d i x . TABLE 6 COEFFICIENTS OF DETERMINATION FOR INTAKES PERIOD I DAILY FEED INTAKES DAILY ENERGY INTAKES DAILY PROTEIN INTAKES Treatment (T) Breed (B) Lactation Category (L) (TXB) Interaction (TXL) Interaction (BXL) Interaction (TXBXL) Interaction Covarlable (Days on Treatment) Total DEGREES OF FREEDOM GRAIN CUBE FEED GRAIN GE CUBE GE FEED GE FEED DE GRAIN CP CUBE CP FEED CP FEED DP 2 .03 .00 .02 .04 .00 .02 .02 .07 .00 .04 .01 1 .48** .32** .44** .49** .32** .45** .45** .45** .33** .43** .43** 1 .33** .37** .32** . 33** . 27** .32** . 32** .30** . 29** .31** .31** 2 .02 .06 .03 .02 .06 .03 .03 .01 .08 .03 .03 2 .02 .01 .02 .02 .01 .02 .02 .02 .01 .02 .02 1 .06 .08 .07 .06 .08 .07 .07 .06 .05 .06 .06 2 .06 .09 .07 .06 .09 .07 .07 .08 . 1 1 .09 .09 1 .OO .02 .01 .OO .02 .01 .01 .00 .00 .00 .OO 26 .75 .68 .74 .74 .68 .73 . 73 .71 .73 .72 . 72 S t a t i s t i c a l s i g n i f i c a n c e *(P<.05). **(P<.01) 75 c . A p p a r e n t D i g e s t i b i l i t y C o e f f i c i e n t s A p p a r e n t d i g e s t i b i l i t y p r e d i c t e d means w i t h t h e i r s t a n d a r d e r r o r s a r e shown i n T a b l e 7. A c o m p a r i s o n o f t h e c o n t r o l r a t i o n w i t h r a t i o n s c o n t a i n i n g p r o t e c t e d t a l l o w r e v e a l e d t h a t t h e r e w e r e no s i g n i f i c a n t d i f f e r e n c e s (P > .05) f o r t h e a p p a r e n t d i g e s t i b i l i t i e s o f D.M., O.M., G.E., N, ADF, t o t a l a s h , C a , P o r Mg. T h e r e were no s i g n i f i c a n t d i f f e r e n c e s (P > .05) b e t w e e n t h e PROTEC S a n d PROTEC R t r e a t m e n t s f o r a n y o f t h e same v a r i a b l e s . T h e p e r c e n t a g e a p p a r e n t d i g e s t i b i l i t y f o r E . E . was s i g n i f i c a n t l y h i g h e r (P < .01) w i t h t h e p r o t e c t e d t a l l o w r a t i o n s a t 81.77 % t h a n on t h e c o n t r o l r a t i o n a t 71.64 %. F u r t h e r m o r e , t h e % E . E . a p p a r e n t d i g e s t i b i l i t y was s i g n i f i c a n t l y h i g h e r (P < .05) on t h e PROTEC R r a t i o n t h a n on t h e PROTEC S r a t i o n . A l t h o u g h t h e d i f f e r e n c e was n o t s i g n i f i c a n t , t h e a p p a r e n t d i g e s t i b i l i t y o f N d e c r e a s e d w i t h t h e i n c o r p o r a t i o n o f p r o t e c t e d t a l l o w i n t h e r a t i o n . T h e 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 t h e a p p a r e n t d i g e s t i b i l i t y v a r i a b l e s a r e p r e s e n t e d i n T a b l e 8. T h e t o t a l R 2 v a l u e s i n d i c a t e t h a t t h e m o d e l f i t t e d f o r t h e s e v a r i a b l e s e x p l a i n e d i n e x c e s s o f 50 % o f t h e v a r i a t i o n i n t h e a p p a r e n t d i g e s t i b i l i t i e s o f D.M., O.M., N, G.E., E . E . , ADF, a n d Mg. T h e m o d e l e x p l a i n e d o n l y 36, 33 a n d 21 % o f t h e v a r i a t i o n i n a p p a r e n t d i g e s t i b i l i t i e s o f t o t a l a s h , Ca a n d P, r e s p e c t i v e l y . T h e r e was a s i g n i f i c a n t t r e a t m e n t e f f e c t (P < .01) f o r E . E . The p r e d i c t e d means ( ± S E M ) o f a p p a r e n t d i g e s t i b i l i t i e s f o r t h e c o n t r o l , PROTEC S a n d PROTEC R r a t i o n E . E . w e r e : 7 1 . 6 4 ± 1 . 5 7 8 , 7 9 . 8 6 ± 1 . 5 5 0 a n d 8 3 . 6 7 ± 1 . 6 6 0 %, r e s p e c t i v e l y . I n a d d i t i o n , t h e r e 76 T A B L E 7. PREDICTED MEAN % APPARENT D I G E S T I B I L I T I E S (DRY MATTER B A S I S ) PERIOD I COMPONENT CONTROL TREATMENT ORTHOGONAL CONTRAST PROTEC S PROTEC R (C) ( S) V S . V S . (S+R) (R) (%) D r y M a t t e r S . E . 71 .04 .499 70.43 .940 70.92 1 .640 NS NS O r g a n i c M a t t e r 72.23 71.72 72.29 S.E. .503 1.010 1.646 NS NS G r o s s E n e r g y S . E . 69.66 1 .578 69.56 1 .550 69.79 1 .660 NS NS E t h e r E x t r a c t S . E . 71 .64 1 .578 79.86 1 .550 83.67 1 .660 P<.01 P<.05 N i t r o g e n S . E . 75.62 .753 72.06 1 .365 73.63 1 .378 NS NS Ac i d - D e t e r g e n t F i b r e 37.14 40.57 40.29 S . E . 2.485 1.493 2.698 NS NS T o t a l A s h S . E . 52. 1 2 2.893 51 .79 1 .571 51.13 2. 102 NS NS C a l c ium S . E . 31 .26 4.916 30. 16 2.477 24.99 3.715 NS NS P h o s p h o r u s S . E . 41.17 6.037 43.39 4.671 45.52 5.730 NS NS M a g n e s i u m S.E. 37.01 3. 1 04 38.97 1 .586 37.77 2.813 NS NS NS: n o t s i g n i f i c a n t TABLE 8. COEFFICIENTS OF DETERMINATION FOR APPARENT DIGESTIBILITIES PERIOD I DIGESTIBILITIES OEGREES SOURCE OF VARIATION S 3 S 3 S S S B B S S S S B S S 8 S S a = S S S S 3 Treatment (T) Lactation Category (L) (TXL) Interaction Covarlable (Feed Intake/Body Weight) Total ur FREEDOM D.M. O.M. N G.E . E . E . ADF ASH Ca P Mg 2 .01 .01 .31 .00 . .54** . 10 .09 . 12 .01 .03 1 . 10 .09 .01 .06 .02 . 17 . 11 .28 .02 . 14 2 . 12 . 12 . 13 . 17 . 10» .09 .07 .01 .05 . 15 1 .05 .04 .05 .07 .01 . 19 .03 .05 .04 .08 1 1 .57 .54 .74 .66 .97 .68 .36 .33 .21 . 52 : c B s s a a S t a t i s t i c a l s i g n i f i c a n c e . »(P<.05C). »*(P<.01), 78 was a s i g n i f i c a n t t r e a t m e n t by l a c t a t i o n c a t e g o r y i n t e r a c t i o n (P < .05) f o r E . E . T h e p r e d i c t e d means a n d s t a n d a r d e r r o r s f o r s i g n i f i c a n t s o u r c e s o f v a r i a t i o n s a r e o u t l i n e d i n T a b l e I V o f t h e A p p e n d i x . S a m p l e s o f f e e d , f a e c e s a n d u r i n e were c o m p o s i t e d f o r d a y s 1-4 a n d 5-7 f o r s e p a r a t e c h e m i c a l a n a l y s i s . T h e d i g e s t i b i l i t y c o e f f i c i e n t s f o r a l l t h e c h e m i c a l c o m p o n e n t s a n a l y z e d w e r e d e t e r m i n e d f o r d a y s 1-4 a n d 1-7 o f t h e 7-day d i g e s t i b i l i t y s t u d y . T h e p u r p o s e o f t h i s was t o c o m p a r e t h e S . E . o f t h e mean a s s o c i a t e d w i t h a 4-day c o l l e c t i o n p e r i o d v e r s u s t h a t f o r a 7-d a y c o l l e c t i o n . T h e r e s u l t s p r e s e n t e d i n T a b l e 7 a r e b a s e d on t h e d i g e s t i b i l i t y c o e f f i c i e n t s f o r d a y s 1-7. T h e p r e d i c t e d means a n d s t a n d a r d e r r o r s f o r t h e d a y s 1-4 c o l l e c t i o n p e r i o d a r e p r e s e n t e d i n T a b l e V o f t h e A p p e n d i x . d . U r i n a r y N i t r o g e n T a b l e 9 shows t h e u r i n a r y o u t p u t s a n d n i t r o g e n e x c r e t i o n d u r i n g t h e d i g e s t i b i l i t y t r i a l . W i t h p r o t e c t e d t a l l o w t h e r e was 6.7 % l e s s u r i n a r y n i t r o g e n e x c r e t i o n t h a n w i t h t h e c o n t r o l r a t i o n , t h i s d i f f e r e n c e n o t b e i n g s i g n i f i c a n t . 79 T A B L E 9. URINARY VOLUME AND NITROGEN EXCRETION D I G E S T I B I L I T Y T R I A L PERIOD I CONTROL PROTEC S PROTEC R ( 1 / c o w / d a y ) U r i n e V o l u m e 14.63 14.20 12.96 S.D. 6.825 5.388 4.835 ( g / c o w / d a y ) N O u t p u t 154.9 149.1 139.9 S.D. 44.99 33.19 37.43 e. P r o d u c t i o n P a r a m e t e r s i . M i l k a n d M i l k E n e r g y P r e d i c t e d mean d a i l y , p e r cow o u t p u t s o f m i l k , 4% f a t -c o r r e c t e d m i l k ( F C M ) , s o l i d s - c o r r e c t e d m i l k (SCM) a n d m i l k G.E., w i t h t h e i r c o r r e s p o n d i n g s t a n d a r d e r r o r s a r e shown i n T a b l e 10. P r o t e c t e d t a l l o w r a t i o n s p r o d u c e d s i g n i f i c a n t l y h i g h e r (P < .05) m i l k a n d FCM y i e l d s t h a n d i d t h e c o n t r o l r a t i o n . M i l k y i e l d r o s e f r o m t h e c o n t r o l l e v e l o f 23.07 k g / c o w / d a y t o a n a v e r a g e o f 27.93 k g / c o w / d a y w i t h p r o t e c t e d t a l l o w . T h e m i l k y i e l d s o f 28.36 k g / c o w / d a y f o r t h e PROTEC S r a t i o n a n d 27.49 k g / c o w / d a y f o r t h e PROTEC R r a t i o n , 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 (P > . 0 5 ) . S i m i l a r l y , FCM r o s e f r o m 18.98 k g / c o w / d a y f o r t h e c o n t r o l t r e a t m e n t t o 23.36 k g / c o w / d a y w i t h p r o t e c t e d t a l l o w . 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 b e t w e e n t h e 24.32 k g / c o w / d a y 80 T A B L E 10. PREDICTED MEAN D A I L Y , PER COW Y I E L D S OF MILK AND MILK ENERGY PERIOD I ORTHOGONAL TREATMENT CONTRAST (C) ( S) V S . V S . COMPONENT CONTROL PROTEC S PROTEC R (S+R) (R) ( k g / c o w / d a y ) M i l k S . E . 23.07 2.664 28.36 1 .734 27.49 2.760 P<.05 NS M i l k , 4% f a t -c o r r e c t e d S . E . 18.98 1 .987 24.32 1 .434 22.39 2. 103 P<.05 NS M i l k , s o l i d s -c o r r e c t e d S .E. 20.48 2. 1 58 25. 18 1 .437 23.66 2. 1 62 NS NS ( M J / c o w / d a y ) M i l k G.E. S.E. 64.22 6.766 78.99 4.506 74.22 6.778 NS NS NS: n o t s i g n i f i c a n t o f FCM w i t h t h e PROTEC S r a t i o n a n d t h e 22.39 k g / c o w / d a y o f FCM p r o d u c e d w i t h t h e PROTEC R r a t i o n (P > . 0 5 ) . S o l i d s - c o r r e c t e d m i l k p r o d u c t i o n / c o w / d a y on t h e c o n t r o l , PROTEC S a n d PROTEC R t r e a t m e n t s was 2 0 . 4 8 , 25.18 a n d 23.66 k g , r e s p e c t i v e l y . T h e r e w e r e no s i g n i f i c a n t d i f f e r e n c e s b e t w e e n t h e c o n t r o l r a t i o n a n d t h o s e c o n t a i n i n g p r o t e c t e d t a l l o w o r b e t w e e n t h e PROTEC S a n d PROTEC R t r e a t m e n t s (P > . 0 5 ) . M i l k G.E. w h i c h i s d i r e c t l y r e l a t e d t o SCM, t e n d e d t o 81 i n c r e a s e on r a t i o n s c o n t a i n i n g p r o t e c t e d t a l l o w v e r s u s t h e c o n t r o l t r e a t m e n t b u t t h i s i n c r e a s e was n o t s i g n i f i c a n t (P > . 0 5 ) . T h e r e was no d i f f e r e n c e b e t w e e n t h e PROTEC S a n d PROTEC R r a t i o n s f o r m i l k G.E. p r o d u c e d (P > . 0 5 ) . i i . M i l k C omponent P e r c e n t a g e s T h e p r e d i c t e d means f o r p e r c e n t a g e s o f m i l k c o m p o n e n t s a r e o u t l i n e d i n T a b l e 11. When c o m p a r e d t o t h e 3.11 % m i l k f a t on t h e c o n t r o l r a t i o n , t h e 3.14 % a n d 3.06 % m i l k f a t on t h e PROTEC S a n d PROTEC R r a t i o n s , r e s p e c t i v e l y , w e r e 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 . T h e d i f f e r e n c e o f .08 p e r c e n t a g e p o i n t s b e t w e e n t h e m i l k f a t % f o r t h e PROTEC S a n d PROTEC R r a t i o n s was n o t s i g n i f i c a n t (P > . 0 5 ) . M i l k p r o t e i n % was s i g n i f i c a n t l y d e c r e a s e d (P < .01) on r a t i o n s c o n t a i n i n g p r o t e c t e d t a l l o w . M i l k p r o t e i n % on t h e c o n t r o l , PROTEC S a n d PROTEC R r a t i o n s was 3.45, 3.08 a n d 3.22 %, r e s p e c t i v e l y . 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 > .05) b e t w e e n t h e e f f e c t s o f t h e PROTEC S a n d PROTEC R r a t i o n s f o r m i l k p r o t e i n %. M i l k l a c t o s e % 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 f o r r a t i o n s w i t h a d d e d p r o t e c t e d t a l l o w (P > . 0 5 ) . I n a d d i t i o n , t h e e f f e c t o f t h e PROTEC S t r e a t m e n t was n o t d i f f e r e n t f r o m t h a t o f t h e PROTEC R (P > . 0 5 ) . 82 T A B L E 11. PREDICTED MEAN DA I L Y MILK COMPONENT PERCENTAGES AND Y I E L D S PERIOD I ORTHOGONAL TREATMENT CONTRAST COMPONENT CONTROL PROTEC S PROTEC R (C) V S . (S+R) ( S ) V S . (R) P e r c e n t a g e (%) — M i l k F a t 3.11 3.14 3.06 NS NS S. E . .189 . 140 .223 M i l k P r o t e i n 3.45 3.08 3.22 P<.01 NS S. E . .082 .072 .052 M i l k L a c t o s e 5.24 5.24 5.25 NS NS S.E. .071 .035 .046 Y i e l d ( k g / c o w / d a y ) M i l k F a t .648 .868 .760 P<.05 NS S.E. .067 .055 .072 M i l k P r o t e i n .784 .861 .866 NS NS S.E. .083 .044 . 145 M i l k L a c t o s e 1 .220 1 .488 1 .445 NS NS S. E . .146 .094 .144 NS: n o t s i g n i f i c a n t i i i . M i l k C omponent Y i e l d s P r e d i c t e d mean d a i l y , p e r cow y i e l d s o f m i l k f a t , p r o t e i n a n d l a c t o s e a r e p r e s e n t e d i n T a b l e 11. M i l k f a t y i e l d was s i g n i f i c a n t l y h i g h e r (P < .05) on r a t i o n s c o n t a i n i n g p r o t e c t e d t a l l o w (.814 k g / c o w / d a y ) t h a n on t h e c o n t r o l r a t i o n (.648 k g / c o w / d a y ) . T h e .868 kg m i l k f a t 83 p r o d u c e d p e r cow p e r d a y w i t h PROTEC S 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 > .05) f r o m t h e .760 k g / c o w / d a y p r o d u c e d w i t h PROTEC R. E v e n t h o u g h m i l k p r o t e i n % was s i g n i f i c a n t l y d e c r e a s e d (P <.01) w i t h p r o t e c t e d t a l l o w , a s s e e n p r e v i o u s l y , 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 m i l k p r o t e i n y i e l d b e t w e e n t h e c o n t r o l r a t i o n a n d t h e r a t i o n s c o n t a i n i n g p r o t e c t e d t a l l o w (P > . 0 5 ) . I n f a c t , t h e r e was a n i n c r e a s i n g t r e n d i n m i l k p r o t e i n y i e l d on t h e p r o t e c t e d t a l l o w r a t i o n s . 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 b e t w e e n t h e PROTEC S a n d PROTEC R t r e a t m e n t s f o r m i l k p r o t e i n y i e l d (P > . 0 5 ) . M i l k l a c t o s e y i e l d i n c r e a s e d f r o m 1 .220 k g / c o w / d a y on t h e c o n t r o l r a t i o n t o a n a v e r a g e o f 1.466 k g / c o w / d a y w i t h p r o t e c t e d t a l l o w . H o w e v e r , t h i s i n c r e a s e was n o t s i g n i f i c a n t (P > . 0 5 ) . T h e r e was no d i f f e r e n c e b e t w e e n t h e two p r o t e c t e d t a l l o w r a t i o n s f o r m i l k l a c t o s e y i e l d (P > . 0 5 ) . 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 m i l k , FCM, SCM, m i l k G.E., m i l k c o m p o n e n t p e r c e n t a g e s a n d m i l k c o m p o n e n t y i e l d s a r e s u m m a r i z e d i n T a b l e 12. T h e R 2 v a l u e s i n d i c a t e t h e m o d e l a c c o u n t e d f o r g r e a t e r t h a n 70 % o f t h e v a r i a t i o n i n m i l k , FCM, SCM, m i l k G.E., m i l k p r o t e i n a n d l a c t o s e y i e l d s , a n d m i l k f a t %. T h e m o d e l d i d n o t e x p l a i n a s much o f t h e v a r i a b i l i t y i n m i l k p r o t e i n %, m i l k l a c t o s e % o r m i l k f a t y i e l d w i t h t o t a l R 2 v a l u e s b e i n g .57, .41 a n d .66, r e s p e c t i v e l y T h e b r e e d e f f e c t was s i g n i f i c a n t f o r s e v e r a l v a r i a b l e s w i t h t h e H o l s t e i n s p r o d u c i n g more m i l k , FCM, SCM, m i l k G.E. m i l k TABLE 12. COEFFICIENTS OF DETERMINATION FOR MILK YIELD AND COMPOSITION PERIOD I SOURCE OF VARIATION DAILY MILK YIELD VARIABLES MILK COMPONENT PERCENTS MILK COMPONENT YIELDS DEGREES OF FREEDOM MILK 4% FCM SCM MILK GE FAT PROTEIN LACTOSE FAT PROTEIN LACTOSE 2 .08 . 12 .09 .09 .00 .34* .00 . 16 .02 .07 1 . 16** .09* . 12* .11* .28** .01 .04 .03 . 17** .17** 1 .50** .43** .46** .46** . 15** .04 .02 . 30** .50** .49** 2 .02 .02 .02 .02 .01 . 13 .00 .02 .04 .02 2 .04 .03 .03 .03 .02 .05 .20 .03 .04 .02 1 .01 .00 .00 .00 .29** .02 .00 .01 .02 .01 2 .21** .21* . 20* . 20* .08 . 15 .01 . 17 . 16* .21** 1 .05 .06 .07 .07 .00 .00 .07 .05 .07 .06 26 .80 .73 .75 .75 .79 .57 .41 .66 .79 .79 Treatment (T) Breed (B) Lactation Category (L) (TXB) Interaction (TXL) Interaction (BXL) Interaction (TXBXL) Interaction Covarlable (Days on Treatment) Total S t a t i s t i c a l s i g n i f i c a n c e . *(P<.05), **(P<.01). CO |4> 85 p r o t e i n a n d m i l k l a c t o s e , w i t h a l o w e r m i l k f a t % t h a n t h e A y r s h i r e s . L a c t a t i o n c a t e g o r y was s i g n i f i c a n t f o r a l l v a r i a b l e s e x c e p t m i l k p r o t e i n a n d l a c t o s e p e r c e n t a g e s . T h e ^ 2nd l a c t a t i o n cows p r o d u c e d more m i l k , FCM, SCM, m i l k G.E., a n d m i l k p r o t e i n , l a c t o s e a n d f a t y i e l d s t h a n d i d t h e h e i f e r s , b u t l e s s m i l k f a t %. T h e ( T x B x L ) i n t e r a c t i o n was s i g n i f i c a n t f o r m i l k , FCM, SCM, m i l k p r o t e i n a n d l a c t o s e y i e l d s (P < . 0 5 ) . The p r e d i c t e d means a n d s t a n d a r d e r r o r s f o r t h e s i g n i f i c a n t b r e e d , l a c t a t i o n c a t e g o r y a n d f i r s t o r d e r i n t e r a c t i o n s a r e o u t l i n e d i n T a b l e I o f t h e A p p e n d i x f o r i n t a k e s , m i l k a n d m i l k c o m p o n e n t y i e l d s , a n d f o r m i l k f a t % i n T a b l e I I o f t h e A p p e n d i x . f . E f f i c i e n c y R a t i o s i . E n e r g y The p r e d i c t e d mean e f f i c i e n c y r a t i o s f o r m i l k o u t p u t p e r u n i t o f G.E. a n d D.E. i n p u t s a r e shown i n T a b l e s 13 a n d 14, r e s p e c t i v e l y . R a t i o n s w i t h p r o t e c t e d t a l l o w p r o d u c e d i n c r e a s e s i n t h e e f f i c i e n c i e s o f p r o d u c t i o n o v e r t h e c o n t r o l r a t i o n a s f o l l o w s : m i l k / G . E . (+21 % ) , FCM/G.E. (+24 % ) , SCM/G.E. (+21 % ) , m i l k G.E./G.E. (+20 % ) , m i l k / D . E . (+21 % ) , FCM/D.E. (+23 % ) , SCM/D.E. (+20 % ) , a n d m i l k G.E./D.E. (+20 % ) . T h e s e i n c r e a s e s w e r e s i g n i f i c a n t (P < .05) i n a l l c a s e s . T h e r e w e r e no 86 T A B L E 13. PREDICTED MEAN MILK OUTPUT/G.E. INPUT E F F I C I E N C Y RATIOS PERIOD I ORTHOGONAL TREATMENT CONTRAST COMPONENT CONTROL PROTEC S PROTEC R (C) V S . (S+R) ( S ) V S . (R) O u t p u t / I n p u t - ( k g / M J ) M i l k / G . E . .070 .085 .085 P<.05 NS S.E. .0066 .0034 .0070 4% FCM/G.E. .058 .074 .070 P<.05 NS S.E. .0047 .0038 .0054 SCM/G.E. .062 .076 .074 P<.05 NS S.E. .0051 .0037 .0054 -- (MJ/MJ) M i l k G.E./G.E. . 196 .239 .233 P<.05 NS S.E. .0160 .0116 .0169 NS: n o t s i g n i f i c a n t d i f f e r e n c e s b e t w e e n t h e PROTEC S a n d PROTEC R t r e a t m e n t s (P > .05) f o r a n y o f t h e s e e f f i c i e n c y r a t i o s . T h e 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 t h e e n e r g y e f f i c i e n c y r a t i o s a r e p r e s e n t e d i n T a b l e 15. The m o d e l w h i c h was f i t t e d t o t h e e n e r g y e f f i c i e n c y r a t i o s a c c o u n t e d f o r 70-78 % o f t h e v a r i a b i l i t y i n t h e d e p e n d e n t v a r i a b l e s . T h e t r e a t m e n t e f f e c t was s i g n i f i c a n t (P < .05) f o r FCM/G.E. a n d FCM/D.E. b u t t h e t r i a l d e s i g n d i c t a t e s t h a t t h e e f f e c t s o f t h e p r o t e c t e d t a l l o w u s e d i n t h i s t r i a l a r e b e s t 87 T A B L E 14. PREDICTED MEAN MILK OUTPUT/D.E. INPUT E F F I C I E N C Y RATIOS PERIOD I ORTHOGONAL TREATMENT CONTRAST COMPONENT CONTROL PROTEC S PROTEC R (C) V S . (S+R) (S ) V S . (R) O u t p u t / I n p u t — ( k g / M J ) M i l k / D . E . .100 .121 .121 P<.05 NS S.E. .0094 .0049 .0099 4% FCM/D.E. .083 . 105 .100 P<.05 NS S. E . .0067 .0054 .0076 SCM/D.E. .089 . 108 . 105 P<.05 NS S. E . .0073 .0052 .0077 -- (MJ/MJ) M i l k G.E./D.E. .280 .340 .330 P<.05 NS S.E. .0230 .01 63 .0238 NS: n o t s i g n i f i c a n t e v a l u a t e d on t h e b a s i s o f t h e o r t h o g o n a l c o n t r a s t s ( T a b l e 14) a l r e a d y d i s c u s s e d . T h e l a c t a t i o n c a t e g o r y e f f e c t was s i g n i f i c a n t (P < .01) f o r a l l e n e r g y e f f i c i e n c y r a t i o s i n c l u d e d i n T a b l e 15. T h e > 2 n d l a c t a t i o n cows p r o d u c e d more m i l k , FCM, SCM, a n d m i l k e n e r g y p e r u n i t o f G.E. o r D.E. i n t a k e t h a n t h e h e i f e r s . T h e p r e d i c t e d means a n d t h e i r s t a n d a r d e r r o r s f o r t h e l a c t a t i o n c a t e g o r i e s a r e p r e s e n t e d i n T a b l e I I I o f t h e A p p e n d i x . T h e ( T x B x L ) i n t e r a c t i o n was s i g n i f i c a n t f o r a l l e n e r g y e f f i c i e n c y r a t i o s . TABLE 15. COEFFICIENTS OF DETERMINATION FOR ENERGY EFFICIENCY RATIOS PERIOD I OUTPUT/GROSS ENERGY INPUT OUTPUT/DIGESTIBLE ENERGY INPUT SOURCE OF VARIATION DEGREES OF FREEDOM MILK 4% FCM SCM MILK GE MILK 4% FCM SCM MILK GE 2 . 13 . 18* . 14 . 14 . 12 . 17* . 16 . 13 1 .03 .00 .00 .00 .03 .00 .00 .00 1 .36** . 22** . 26** .26** . 33** .22** .26** . 26** 2 .01 .03 .04 .04 .01 .03 .04 .04 2 .05 .04 .03. .03 .05 .04 .03 .03 1 .01 .01 .00 .00 .01 .01 .00 .00 2 .24* . 22* .21* .21* .24* . 22* .21* .21* 1 .06 .05 .07 .07 .06 .05 .07 .07 26 . 73 .72 .70 .71 . 73 .71 .70 : S S 3 S S 3 = = = = .70 Treatment (T) Breed (B) Lactation Category (L) (TXB) Interaction (TXL) Interaction (BXL) Interaction (TXBXL) Interaction Covarlable (Days on Treatment) Total S t a t i s t i c a l s i g n i f i c a n c e . *(P<.05). **(P<.01). 89 i i . P r o t e i n T a b l e 16 c o n t a i n s t h e p r e d i c t e d mean e f f i c i e n c y r a t i o s f o r m i l k o u t p u t / C P . i n p u t . T a b l e 17 c o n t a i n s t h e p r e d i c t e d mean T A B L E 16. PREDICTED MEAN MILK O U T P U T / C P . INPUT E F F I C I E N C Y RATIOS PERIOD I ORTHOGONAL TREATMENT CONTRAST (C) (S) VS . V S . COMPONENT CONTROL PROTEC S PROTEC R (S+R) (R) O u t p u t / I n p u t ( k g / k g ) M i l k / C P . 7.76 9.35 9.47 P<.05 NS S.E. .715 .360 .801 4% FCM/C.P. 6.44 9.08 7.83 P<.05 NS S.E. .516 .418 .611 SCM/C.P. 6.93 9.26 9.26 P<.05 NS S.E. .567 .404 .618 (MJ / k g ) M i l k G . E . / C P . 21.73 26.23 25.91 P<.05 NS S.E. 1.777 1.266 1.937 NS: n o t s i g n i f i c a n t e f f i c i e n c y r a t i o s f o r m i l k o u t p u t / D . P . i n p u t . R a t i o n s c o n t a i n i n g p r o t e c t e d t a l l o w c a u s e d i n c r e a s e s i n t h e e f f i c i e n c i e s o f p r o d u c t i o n o v e r t h e c o n t r o l r a t i o n a s f o l l o w s : 90 T A B L E 17. PREDICTED MEAN MILK OUTPUT/D.P. INPUT E F F I C I E N C Y RATIOS PERIOD I ORTHOGONAL TREATMENT CONTRAST (C) (S) V S . VS. COMPONENT CONTROL PROTEC S PROTEC R (S+R) (R) M i l k / D . P . 10.21 12.80 12.70 P<.05 NS S. E . .942 .493 1.074 4% FCM/D.P. 8.47 11.06 10.50 P<.01 NS S. E . .680 .572 .820 SCM/D.P. 9.12 11.45 11.08 P<.05 NS S . E . . .746 .553 .828 ( M J / k g ) M i l k G.E./D.P. 28.61 35.90 34.75 P<.05 NS S. E . 2.340 1.733 2.597 NS: n o t s i g n i f i c a n t m i l k / C P . ( + 21 % ) , FCM/C.P. ( + 24 % ) , SCM/C.P. ( + 20 % ) , m i l k G . E . / C P . (+20 % ) , m i l k / D . P . (+25 % ) , FCM/D.P. (+27 % ) , SCM/D.P. (+24 % ) , a n d m i l k G.E./D.P. (+23 % ) . T h e i n c r e a s e s i n e f f i c i e n c y o f u t i l i z a t i o n o f d i e t a r y p r o t e i n w e r e s i g n i f i c a n t (P < .05) i n a l l c a s e s . T h e i n c r e a s e i n FCM/D.P. was s i g n i f i c a n t a t P < .01. T h e PROTEC S a n d PROTEC R r a t i o n s w e r e n o t d i f f e r e n t (P > .05) f o r a n y o f t h e m i l k o u t p u t / p r o t e i n i n p u t e f f i c i e n c y r a t i o s . T h e 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 t h e p r o t e i n 91 e f f i c i e n c y r a t i o s a r e p r e s e n t e d i n T a b l e 18. Th e t o t a l R 2 v a l u e s i n d i c a t e t h e m o d e l f i t t e d t o t h e p r o t e i n e f f i c i e n c y r a t i o s e x p l a i n e d f r o m 69-74 % o f t h e v a r i a t i o n i n t h e d e p e n d e n t v a r i a b l e s . T h e t r e a t m e n t e f f e c t was s i g n i f i c a n t f o r m i l k / D . P . , FCM/C.P., FCM/D.P., SCM/D.P. a n d m i l k G.E./D.P. T h e o r t h o g o n a l c o n t r a s t s c o n s i d e r e d w i t h t h e a n a l y s i s o f v a r i a n c e w e r e u s e d t o e v a l u a t e t h e e f f e c t s o f p r o t e c t e d l i p i d s r a t h e r t h a n t h e t r e a t m e n t e f f e c t , t h e l a t t e r b e i n g o f l i m i t e d i n t e r e s t i n t h i s s t u d y . A s w i t h t h e e n e r g y e f f i c i e n c y r a t i o s , t h e l a c t a t i o n c a t e g o r y e f f e c t was s i g n i f i c a n t f o r a l l p r o t e i n e f f i c i e n c y r a t i o s (P < . 0 1 ) , w i t h t h e ^ 2nd l a c t a t i o n cows p r o d u c i n g more o u t p u t p e r u n i t o f p r o t e i n t h a n t h e h e i f e r s . T h e p r e d i c t e d means a n d t h e i r s t a n d a r d e r r o r s , by l a c t a t i o n c a t e g o r y a r e c o n t a i n e d i n T a b l e I I I o f t h e A p p e n d i x . The ( T x B x L ) i n t e r a c t i o n was s i g n i f i c a n t f o r a l l p r o t e i n e f f i c i e n c y r a t i o s . TABLE 18. COEFFICIENTS OF DETERMINATION FOR PROTEIN EFFICIENCY RATIOS PERIOD 1 SOURCE OF VARIATION DEGREES OF FREEDOM OUTPUT/CRUDE PROTEIN INPUT OUTPUT/DIGESTIBLE PROTEIN INPUT MILK 4% FCM SCM MILK GE MILK 4% FCM SCM MILK GE Treatment (T) 2 . 12 . 16* . 13 . 13 . 16* .21* . 17* . 17* Breed (B) 1 .03 .00 .00 .00 .03 .00 .00 .00 Lactation Category (L) 1 . 35** . 20** . 24** .24** .34** . 20** . 23** . 23** (TXB) Interaction 2 .02 .04 .05 .05 .02 .04 .05 .05 (TXL) Interaction 2 .05 .04 .03 .03 .05 .04 .03 .03 (BXL) Interaction 1 .01 .01 .00 .OO .01 .01 .00 .00 (TXBXL) Interaction 2 .22* .20* . 20* . 20* . 22* . 20* . 19* . 19* Covartable 1 .07 .06 .08 .08 .07 .06 .08 .08 (Days on T r i a l ) .72 .71 .71 Total 26 .73 .71 .70 .69 . 74 S t a t i s t i c a l s i g n i f i c a n c e . *(P<.05). **(P<.01). to 93 g . A v e r a g e D a i l y G a i n s P r e d i c t e d mean a v e r a g e d a i l y g a i n s (A.D.G.) a r e s u m m a r i z e d i n T a b l e 19. T h e c o n t r o l , PROTEC S a n d PROTEC R r a t i o n s T A B L E 19. PREDICTED MEAN AVERAGE D A I L Y GAINS PERIOD I ORTHOGONAL TREATMENT CONTRAST (C) ( S) VS. V S . COMPONENT CONTROL PROTEC S PROTEC R (S+R) (R) ( k g / c o w / d a y ) A v e . D a i l y G a i n .336 .189 .231 NS NS S . E . .0972 .0882 .1153 NS: n o t s i g n i f i c a n t p r o d u c e d A.D.G.s o f .336, .189 a n d .231 k g / d a y , r e s p e c t i v e l y . 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 b e t w e e n r a t i o n s w i t h a n d w i t h o u t p r o t e c t e d t a l l o w , o r b e t w e e n t h e PROTEC S a n d PROTEC R r a t i o n s f o r A.D.G. (P > . 0 5 ) . 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 A.D.G. a r e p r e s e n t e d i n T a b l e 2 0. T h e b r e e d e f f e c t was s i g n i f i c a n t (P < .05) f o r A.D.G. T h e p r e d i c t e d mean A.D.G. ( a n d i t s s t a n d a r d e r r o r ) f o r H o l s t e i n s w e r e . 3 9 7 ( . 0 7 5 0 ) k g / d a y w h i l e t h e c o r r e s p o n d i n g v a l u e s f o r A y r s h i r e s w e r e . 1 0 7 ( . 0 5 5 8 ) k g / d a y . 94 T A B L E 20. C O E F F I C I E N T S OF DETERMINATION FOR A.D.G. PERIOD I DEGREES AVERAGE OF D A I L Y SOURCE OF V A R I A T I O N FREEDOM GAIN B r e e d (B) 1 - 1 8* T r e a t m e n t ( T ) 2 .03 L a c t a t i o n C a t e g o r y ( L ) 1 .00 (TXB) I n t e r a c t i o n 2 .08 ( T X L ) I n t e r a c t i o n 2 .04 (BXL) I n t e r a c t i o n 1 .06 ( T X B X L ) I n t e r a c t i o n 2 .05 T o t a l 26 .55 S t a t i s t i c a l s i g n i f i c a n c e : * ( P < . 0 5 ) . h . B l o o d M e t a b o l i t e s B l o o d p l a s m a m e t a b o l i t e c o n c e n t r a t i o n s a r e shown i n T a b l e 21 . i . G l u c o s e P l a s m a g l u c o s e c o n c e n t r a t i o n 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 > .05) w i t h p r o t e c t e d t a l l o w i n t h e r a t i o n t h a n f o r t h e c o n t r o l r a t i o n . T h e r e was no d i f f e r e n c e b e t w e e n g l u c o s e c o n c e n t r a t i o n s on t h e PROTEC S v e r s u s t h e PROTEC R t r e a t m e n t s (P > . 0 5 ) . T h e 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 p l a s m a g l u c o s e a r e s u m m a r i z e d i n T a b l e 22. T h e l a c t a t i o n c a t e g o r y e f f e c t was s i g n i f i c a n t (P < .01) w i t h t h e p r e d i c t e d mean p l a s m a g l u c o s e c o n c e n t r a t i o n ( a n d t h e s t a n d a r d e r r o r ) f o r > 2 n d l a c t a t i o n cows 95 T A B L E 2 1 . PREDICTED MEAN PLASMA M E T A B O L I T E CONCENTRATIONS PERIOD I ORTHOGONAL TREATMENT CONTRAST (C) ( S) V S . VS. M ETABOLITE CONTROL PROTEC S PROTEC R (S+R) (R) (mg %) 65.4 63.8 66.1 NS NS 1.09 1.10 1.04 ( u m o l e / 1 ) NEFA 230.4 319.6 284.4 P<.01 NS S.E. 13.50 20.75 19.51 NS: n o t s i g n i f i c a n t a n d h e i f e r s b e i n g 6 1 . 9 ( . 7 6 ) mg % a n d 6 8 . 3 ( . 6 8 ) mg %, r e s p e c t i v e l y . i i . N o n - E s t e r i f i e d F a t t y A c i d s NEFA l e v e l s i n p l a s m a w e r e s i g n i f i c a n t l y e l e v a t e d (P < .01) w i t h t h e r a t i o n s c o n t a i n i n g p r o t e c t e d t a l l o w ( a v e r a g e = 302.0 u m o l e / 1 ) o v e r t h e c o n t r o l r a t i o n ( 2 3 0 . 4 u m o l e / 1 ) . T h e r e was no d i f f e r e n c e b e t w e e n t h e e f f e c t s o f t h e PROTEC S a n d PROTEC R r a t i o n s on p l a s m a NEFA l e v e l s (P > . 0 5 ) . 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 p l a s m a NEFA c o n c e n t r a t i o n a r e s u m m a r i z e d i n T a b l e 22. W i t h t h e m o d e l f i t t e d , t h e e f f e c t s o f t r e a t m e n t (P < . 0 1 ) , G l u c o s e S.E. 96 T A B L E 2 2 . C O E F F I C I E N T S OF DETERMINATION ( R 2 ) FOR BLOOD METABOLITES PERIOD I DEGREES OF PLASMA PLASMA SOURCE OF V A R I A T I O N FREEDOM GLUCOSE NEFAS T r e a t m e n t ( T ) 2 .02 .11** B r e e d (B) 1 .00 .00 L a c t a t i o n C a t e g o r y ( L ) 1 .22** .06* (TXB) I n t e r a c t i o n 2 .01 .02 ( T X L ) I n t e r a c t i o n 2 .03 .06* ( B X L ) I n t e r a c t i o n 1 .00 .00 ( T X B X L ) I n t e r a c t i o n 2 .05 .10** C o v a r i a b l e 1 .00 .08** ( D a y s on T r e a t m e n t ) T o t a l 26 .44 .40 S t a t i s t i c a l s i g n i f i c a n c e . * ( P < . 0 5 ) , * * ( P < . 0 1 ) . l a c t a t i o n c a t e g o r y (P < . 0 5 ) , t r e a t m e n t by l a c t a t i o n c a t e g o r y i n t e r a c t i o n (P < . 0 5 ) , ( T x B x L ) i n t e r a c t i o n (P < .01) a n d t h e c o v a r i a b l e (P < .01) were a l l s i g n i f i c a n t . T h e p r e d i c t e d means p l u s t h e a s s o c i a t e d s t a n d a r d e r r o r s f o r t h e l a c t a t i o n c a t e g o r y a n d t h e t r e a t m e n t by l a c t a t i o n i n t e r a c t i o n a r e shown i n T a b l e VI o f t h e A p p e n d i x . 97 i . Rumen V o l a t i l e F a t t y A c i d s Th e a v e r a g e v a l u e s p e r t r e a t m e n t f o r t h e m o l a r p e r c e n t a g e s o f rumen V F A s a r e p r e s e n t e d i n T a b l e 2 3 . T A B L E 23. MOLAR PERCENTAGES OF RUMEN V O L A T I L E F A T T Y ACIDS PERIOD I V O L A T I L E F A T T Y A C I D TREATMENT CONTROL PROTEC S PROTEC R A c e t i c 67.51 50.87 61 .49 P r o p i o n i c 26.21 33.52 31 .85 B u t y r i c 5.35 13.09 4.86 I s o b u t y r i c .32 .90 .72 V a l e r i c .43 1.12 .70 I s o v a l e r i c .19 .50 1 .28 A c e t a t e / P r o p i o n a t e 2.6:1 1.5:1 1.9:1 The m o l a r % o f a c e t i c a c i d was d e c r e a s e d w i t h p r o t e c t e d t a l l o w i n t h e r a t i o n , f r o m 67.51 % on t h e c o n t r o l t o 61.49 % on t h e PROTEC R r a t i o n a n d f u r t h e r t o 50.87 % on t h e PROTEC S r a t i o n . T h e a v e r a g e % a c e t i c a c i d f o r t h e p r o t e c t e d t a l l o w t r e a t m e n t s was 56.18 %. A t t h e same t i m e , t h e m o l a r % o f p r o p i o n i c a c i d i n c r e a s e d f r o m 26.21 % f o r t h e c o n t r o l t o 31.85 a n d 33.52 % on t h e PROTEC R a n d PROTEC S r a t i o n s , r e s p e c t i v e l y . T h i s r e p r e s e n t s an a v e r a g e o f 32.69 % p r o p i o n i c a c i d on r a t i o n s w i t h p r o t e c t e d t a l l o w . T h e r a t i o o f a c e t i c a c i d : p r o p i o n i c a c i d d e c r e a s e d f r o m 98 2.6:1 f o r t h e c o n t r o l t o a n a v e r a g e o f 1.7:1 f o r r a t i o n s w i t h p r o t e c t e d t a l l o w . 2. P e r i o d I I a . I n t a k e s P r e d i c t e d means f o r d a i l y i n t a k e s o f f e e d s t u f f s , e n e r g y a n d p r o t e i n , w i t h t h e c o r r e s p o n d i n g s t a n d a r d e r r o r s a r e o u t l i n e d i n T a b l e 24. T h e c o n c e n t r a t e i n t a k e s / c o w f o r t h e p o s t - c o n t r o l ( P C ) , p o s t - P R O T E C S (PS) a n d p o s t - P R O T E C R (PR) r a t i o n s w e r e : 13.39, 13.67 a n d 11.59 k g , r e s p e c t i v e l y . T h e r e .were no s i g n i f i c a n t d i f f e r e n c e s i n t h e i n t a k e s o f PC v e r s u s PS a n d PR, b u t t h e i n t a k e o f c o n c e n t r a t e s on PR was s i g n i f i c a n t l y l o w e r t h a n t h a t on PS (P < .05) . T h e r e were no s i g n i f i c a n t d i f f e r e n c e s b e t w e e n t h e PC t r e a t m e n t v e r s u s t h e PS a n d PR t r e a t m e n t s (P > .05) f o r a l f a l f a o r t o t a l D.M. i n t a k e s . G r o s s e n e r g y i n t a k e s f r o m c o n c e n t r a t e s , c u b e s o r t o t a l D.M. d i d n o t d i f f e r (P > .05) b e t w e e n cows p r e v i o u s l y f e d p r o t e c t e d t a l l o w o r n o t . F u r t h e r m o r e , t h e r e w e r e no d i f f e r e n c e s i n G.E. i n t a k e s f r o m c u b e s o r t o t a l D.M. b e t w e e n t h e PS a n d PR t r e a t m e n t s (P > . 0 5 ) , b u t t h e i n t a k e o f c o n c e n t r a t e s was s i g n i f i c a n t l y l o w e r f o r PR t h a n f o r PS (P < . 0 5 ) . T h e PC g r o u p i n t a k e s o f C P . f r o m c o n c e n t r a t e s , c u b e s o r t o t a l f e e d w e r e 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 > .05) f r o m t h e c o r r e s p o n d i n g i n t a k e s by g r o u p s on PS a n d PR. T h e PR i n t a k e o f TABLE 24. PREDICTED MEAN DAILY INTAKES PER COW (DRY MATTER BASIS) PERIOD I I TREATMENT ORTHOGONAL CONTRAST ITEM PC PS PR (C) (S) VS. VS. (S+R) (R) Feed I n t a k e C o n c e n t r a t e 13.39 S.E. .534 A l f a l f a Cubes 5.76 S.E. .259 T o t a l D.M. 19.14 S.E. .911 (kg/cow/day) 1 3.67 .506 5.88 .184 1 9.55 1.010 1 1 .59 1 .047 5.13 .434 16.72 1 .474 NS P<.05 NS NS NS NS Energy I n t a k e C o n c e n t r a t e G.E. 241.3 S.E. 11.78 A l f a l f a G.E. 106.5 S.E. 4.81 T o t a l G.E. 347.9 S.E. 16.55 (MJ/cow/day) 246.4 9.12 108.8 3.42 355.3 12.23 209.0 18.88 94.93 8.04 303.9 26.77 NS P<.05 NS NS NS NS P r o t e i n I n t a k e C o n c e n t r a t e C P . 2.20 S.E. .107 A l f a l f a C P . 1 .04 S.E. .047 T o t a l C P . 3.24 S.E. .154 (kg/cow/day) 2.24 .083 1 .07 .034 3.31 .113 1 .90 .172 0.93 .079 2.83 .250 NS P<.05 NS NS NS NS NS: not s i g n i f i c a n t 100 C P . f r o m c o n c e n t r a t e s was s i g n i f i c a n t l y l o w e r t h a n t h a t f o r PS (P < . 0 5 ) , b u t t h e PR a n d PS i n t a k e s o f C P . f r o m c u b e s o r t o t a l f e e d d i d n o t d i f f e r (P > . 0 5 ) i T h e R 2 v a l u e s f o r d a i l y i n t a k e s o f f e e d s t u f f s , e n e r g y a n d p r o t e i n i n d i c a t e t h e m o d e l f i t t e d t o i n t a k e s , a c c o u n t e d f o r g r e a t e r t h a n 69 % o f t h e v a r i a t i o n i n t h e d e p e n d e n t v a r i a b l e ( T a b l e 2 5 ) . T h e b r e e d e f f e c t was s i g n i f i c a n t f o r a l l i n t a k e v a r i a b l e s w i t h t h e H o l s t e i n s c o n s u m i n g more t h a n t h e A y r s h i r e s . T h e l a c t a t i o n c a t e g o r y e f f e c t was s i g n i f i c a n t f o r a l l i n t a k e v a r i a b l e s . T h e ^ 2 n d l a c t a t i o n c o w s c o n s u m e d more d r y m a t t e r , G.E., a n d C P . t h a n d i d t h e h e i f e r s . A summary o f p r e d i c t e d means w i t h a s s o c i a t e d s t a n d a r d e r r o r s c a n be f o u n d i n T a b l e V I I o f t h e A p p e n d i x f o r a l l s i g n i f i c a n t b r e e d a n d l a c t a t i o n c a t e g o r y e f f e c t s . b . P r o d u c t i o n P a r a m e t e r s i . M i l k a n d M i l k E n e r g y T h e v a l u e s i n T a b l e 26 i n d i c a t e t h e r e was a t e n d e n c y f o r c o w s , p r e v i o u s l y f e d p r o t e c t e d t a l l o w t o p r o d u c e more m i l k , FCM, SCM a n d m i l k e n e r g y t h a n t h e cows t h a t w e r e on t h e c o n t r o l , b u t t h e s e d i f f e r e n c e s w e r e n o t s i g n i f i c a n t (P > . 0 5 ) . T h e r e w e r e no s i g n i f i c a n t d i f f e r e n c e s b e t w e e n t h e PS a n d PR r a t i o n s f o r a n y o f t h e s e v a r i a b l e s (P > . 0 5 ) . T h e PC, PS a n d PR o u t p u t s w e r e : 2 1 . 2 1 , 2 5 . 9 8 , 24.11 k g / c o w / d a y o f m i l k ; 16.47, 19.86, 18.04 k g / c o w / d a y o f FCM; 18.26, 2 1 . 4 3 , 19.79 k g / c o w / d a y o f SCM; TABLE 25. COEFFICIENTS OF DETERMINATION FOR INTAKES PERIOD II FEED INTAKE/DAY ENERGY INTAKE DAY PROTEIN INTAKE/DAY DEGREES OF SOURCE OF VARIATION FREEDOM. GRAIN CUBES TOTAL GRAIN CUBES TOTAL GRAIN CUBES TOTAL Treatment (T) 2 .09 .07 .09 .09 .07 .09 .09 .07 .09 Breed (B) 1 . 38** . 34** . 37** .38** . 34** .37** . 38** . 34** . 37** Lactation Category (L) 1 . 17** . 19** . 18** . 17** . 19** . 18** . 17** . 19** . 18** (TXB) Interaction 2 .08 .05 .07 .08 .05 .07 .08 .05 .07 (TXL) Interaction 2 .01 .00 .01 .01 .00 .01 .01 .00 .01 (BXL) Interaction 1 .01 .01 .01 .01 .01 .01 .01 .01 .01 (TXBXL) Interaction 2 .03 .07 .04 .03 .07 .04 .03 .07 .04 Covariable 1 .03 .03 .03 .03 .03 .03 .03 .03 .03 (Days In Period) .69 .74 Total 26 .76 .69 .75 . 76 .69 .75 .76 ========================= ============= ========== ========== ========== =========== ========== — — = — = — = — ~ ========== ======= S t a t i s t i c a l s i g n i f i c a n c e . *(P<.05), ** (P<.01). 102 T A B L E 26. PREDICTED MEAN D A I L Y , PER COW Y I E L D S OF MILK AND MILK ENERGY PERIOD I I ORTHOGONAL TREATMENT CONTRAST (C) ( S) V S . VS. COMPONENT PC PS PR (S+R) (R) ( k g / c o w / d a y ) M i l k 21.21 25.98 24.11 NS NS S.E. 2.550 1.583 2.915 M i l k , 4% f a t -c o r r e c t e d 16.47 19.86 18.04 NS NS S.E. 1.924 .898 1.837 M i l k , s o l i d s -c o r r e c t e d 18.26 21.43 19.79 NS NS S.E. 2.149 .930 2.093 ( M J / c o w / d a y ) M i l k G.E. 57.28 67.24 62.05 NS NS S.E. 6.739 2.917 6.559 a n d 5 7 . 2 8 , 6 7 . 2 4 , 62.05 MJ/cow/day o f G.E., r e s p e c t i v e l y . T h e 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 d a i l y m i l k y i e l d s a r e s u m m a r i z e d i n T a b l e 28. B r e e d a n d l a c t a t i o n c a t e g o r y e f f e c t s w e r e s i g n i f i c a n t f o r a l l d e p e n d e n t v a r i a b l e s . H o l s t e i n s p r o d u c e d m o r e : m i l k , FCM, SCM a n d m i l k G.E. t h a n t h e A y r s h i r e s (P < .01) a n d t h e > 2 n d l a c t a t i o n cows p r o d u c e d more o f t h e s e same o u t p u t s t h a n t h e h e i f e r s ( P < . 0 1 ) . I n a d d i t i o n , t h e ( T x B x L ) i n t e r a c t i o n was 103 s i g n i f i c a n t f o r m i l k y i e l d s . T h e c o v a r i a b l e ( d a y s i n t h e p e r i o d ) was s i g n i f i c a n t f o r m i l k y i e l d (P < . 0 5 ) . A summary o f p r e d i c t e d means w i t h s t a n d a r d e r r o r s f o r a l l s i g n i f i c a n t e f f e c t s i s c o n t a i n e d i n T a b l e V I I o f t h e A p p e n d i x . i i . M i l k C o m p o s i t i o n T h e p r e d i c t e d means f o r p e r c e n t a g e s a n d y i e l d s o f m i l k f a t , p r o t e i n a n d l a c t o s e a r e p r e s e n t e d i n T a b l e 2 7 . T h e r e were no s i g n i f i c a n t d i f f e r e n c e s f o u n d f o r (PC) v s . (PS + PR) o r f o r (PS) v s . (PR) f o r a n y m i l k c o m p o n e n t p e r c e n t a g e o r y i e l d (P > . 0 5 ) . T h e m o d e l c h o s e n t o d e s c r i b e t h e d a t a was e f f e c t i v e i n e x p l a i n i n g 67, 50 a n d 40 % o f t h e v a r i a t i o n i n m i l k f a t , p r o t e i n a n d l a c t o s e %, r e s p e c t i v e l y a n d 64, 71 a n d 72 % o f t h e v a r i a t i o n i n m i l k f a t , p r o t e i n a n d l a c t o s e y i e l d s , r e s p e c t i v e l y . T h e b r e e d e f f e c t was s i g n i f i c a n t (P < .01) f o r f a t % a n d p r o t e i n a n d l a c t o s e y i e l d s , w i t h H o l s t e i n s p r o d u c i n g l o w e r f a t t e s t m i l k , a n d more m i l k p r o t e i n a n d l a c t o s e y i e l d s t h a n t h e A y r s h i r e s . T h e l a c t a t i o n c a t e g o r y e f f e c t was s i g n i f i c a n t (P < .01) f o r m i l k f a t , p r o t e i n a n d l a c t o s e y i e l d s . T h e b r e e d by l a c t a t i o n i n t e r a c t i o n was s i g n i f i c a n t (P < .05) f o r f a t %. T h e f a t t e s t o f A y r s h i r e h e i f e r s ' m i l k was s i g n i f i c a n t l y h i g h e r t h a n f o r t h e o t h e r h e i f e r s o r c o w s . T h e c o v a r i a b l e ( d a y s i n t h e p e r i o d ) was s i g n i f i c a n t f o r m i l k p r o t e i n a n d l a c t o s e y i e l d s (P < . 0 5 ) . T h e p r e d i c t e d means a n d s t a n d a r d e r r o r s f o r s i g n i f i c a n t 104 T A B L E 27. PREDICTED MEAN D A I L Y MILK COMPONENT PERCENTAGES AND Y I E L D S PERIOD I I COMPONENT PC TREATMENT PS PR ORTHOGONAL CONTRAST (C) ( S) VS . V S . (S+R) (R) P e r c e n t a g e (%) M i l k F a t S . E . 2.67 .222 2.54 .212 2.66 .267 NS NS M i l k P r o t e i n S . E . 3.54 .077 3.33 .080 3.43 .072 NS NS M i l k L a c t o s e S . E . 5.24 .086 5.16 .061 5.20 . 1 02 NS NS Y i e l d ( k g / c o w / d a y ) M i l k F a t S . E . .532 .0689 .631 .0402 .560 .0556 NS NS M i l k P r o t e i n S . E . . . 1 54 .0930 .858 .0442 .808 .0967 NS NS M i l k L a c t o s e S . E . 1.121 .1419 1 .339 .0818 1 .264 .1635 NS NS NS: n o t s i g n i f i c a n t s o u r c e s o f v a r i a t i o n f o r m i l k c o m p o s i t i o n i n p e r i o d I I a r e p r e s e n t e d i n T a b l e 28. TABLE 28. COEFFICIENTS OF DETERMINATION FOR MILK YIELD AND COMPOSITION PERIOD II DAILY MILK YIELDS MILK COMPONENT PERCENTAGES MILK COMPONENT YIELDS D.F. MILK 4% FCM SCM MILK GE FAT PROTEIN LACTOSE FAT PROTEIN LACTOSE Treatment (T) 2 .06 .06 .04 .05 .01 . 10 .01 .05 .02 .04 Bree d (B) 1 .32** .22** .24** .24** . 25** .09 .04 .07 .26** .31** L a c t a t i o n C a t e g o r y (L) 1 .36** .45** .42** .42** .01 .01 .00 .37** .33** .31** (TXB) I n t e r a c t i o n 2 .03 .04 .04 .04 .05 .09 .02 .07 .03 .03 (TXL) I n t e r a c t i o n 2 .03 .09 .06 .06 .02 . 14 .08 . 16 .02 .02 (BXL) I n t e r a c t i o n 1 .00 .00 .00 .00 . 13* .00 .04 .02 .01 .01 (TXBXL) I n t e r a c t i o n 2 . 16* .08 .09 .09 . 14 .03 .03 .01 . 13 . 13 C o v a r 1 a b l e 1 .09* .04 .06 .06 .05 .02 .06 .00 .11* .11* (Days 1n P e r i o d ) .71 .72 T o t a l 26 .78 .74 .72 .72 .67 .50 .40 .64 S t a t i s t i c a l s i g n i f i c a n c e . *(P<.05), **(P<.01). 106 c . E f f i c i e n c y R a t i o s T a b l e s 29 a n d 30 c o n t a i n p r e d i c t e d mean e f f i c i e n c y r a t i o s f o r m i l k o u t p u t s p e r u n i t o f G.E. a n d p e r u n i t o f C P . T A B L E 29. P R E D I C T E D MEAN MILK OUTPUT/G.E. INPUT E F F I C I E N C Y RATIOS PERIOD I I ORTHOGONAL TREATMENT CONTRAST COMPONENT PC PS PR (C) V S . (S+R) (S ) V S . (R) O u t p u t / I n p u t — ( k g / M J ) -M i l k / G . E . .058 .072 .076 P<.01 NS S . E . .0056 .0025 .0054 4% FCM/G.E. .045 .056 .059 P<.01 NS S . E . .0041 .001 6 .0042 SCM/G.E. .050 . 060 .064 P<.01 NS S . E . .0046 .001 4 .0040 -- (MJ/MJ) -M i l k G.E./G.E. . 1 57 .189 .200 P<.01 NS S . E . .01 44 .0043 .0127 NS: n o t s i g n i f i c a n t M i l k , FCM, SCM a n d m i l k G.E. p e r u n i t o f G.E. o r C P i n p u t , were a l l h i g h e r (P < .01) on t h e PS a n d PR r a t i o n s t h a n on t h e PC. T h e r e w e r e no s i g n i f i c a n t d i f f e r e n c e s b e t w e e n PS a n d PR f o r a n y e f f i c i e n c y r a t i o (P > . 0 5 ) . 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 a l l t h e e f f i c i e n c y 107 T A B L E 30 . PREDICTED MEAN MILK O U T P U T / C P . INPUT E F F I C I E N C Y RATIOS PERIOD I I ORTHOGONAL TREATMENT CONTRAST (C) ( S) VS . V S . COMPONENT PC PS PR (S+R) (R) O u t p u t / I n p u t — ( k g / M J ) M i l k / C P . 6.23 7.77 8 .14 P<.01 NS S.E. .600 .263 .577 4% FCM/C.P. 4.86 5.98 6 .30 P<.01 NS S.E. .442 .175 .447 SCM/C.P. 5.37 6.45 6 .85 P<. 01 NS S.E. .490 . 1 46 .430 — (MJ/MJ) M i l k G . E . / C P . 1 6.85 20.24 21 .49 P<.01 NS S.E. 1 .538 .459 1 .349 NS: n o t s i g n i f i c a n t r a t i o s a r e p r e s e n t e d i n T a b l e 3 1 . T r e a t m e n t e f f e c t was s i g n i f i c a n t f o r a l l e f f i c i e n c y r a t i o s . B r e e d e f f e c t was s i g n i f i c a n t f o r m i l k / G . E . w i t h H o l s t e i n s b e i n g more e f f i c i e n t t h a n A y r s h i r e s (P < . 0 1 ) . L a c t a t i o n c a t e g o r y was s i g n i f i c a n t f o r a l l e f f i c i e n c y r a t i o s : h e i f e r s w e r e l e s s e f f i c i e n t p r o d u c e r s t h a n t h e ^ 2nd l a c t a t i o n cows (P < . 0 1 ) . Th e t r e a t m e n t by l a c t a t i o n c a t e g o r y was s i g n i f i c a n t (P < .05) f o r FCM, SCM a n d m i l k G.E. p e r u n i t o f G.E. o r C P . TABLE 31 COEFFICIENTS OF DETERMINATION FOR ENERGY AND PROTEIN EFFICIENCY RATIOS PERIOD II DEGREES OF MILK/GE 4% FCM SCM/GE MILK GE MILK/CP 4% FCM SCM/CP MILK GE SOURCE OF VARIATION FREEDOM /GE /GE /CP /CP Treatment (T) 2 .21** . 19* B r e e d (B) 1 .12** .01 L a c t a t I o n C a t e g o r y ( L) 1 .34** .30** (TXB) 2 .00 .02 (TXL) 2 .08 . 15* (BXL) 1 .01 .00 (TXBXL) 2 .20** .06 C o v a r i a b l e 1 .09* .01 (Days In P e r i o d ) T o t a l 26 .82 .78 S t a t i s t i c a l s i g n i f i c a n c e . *(P<.05). **(P<.01). . 19* . 19* .20** . 19* . 19* . 19* .02 .02 . 12** .01 .02 .02 .34** . 33** .34** .30** . 33** . 33** .02 .02 .00 .02 .02 .02 . 13* . 12* .08 . 15* . 12* . 12* .00 .00 .01 .00 .OO .OO .08 .08 .20** .06 .08 .08 .04 .04 .09* .01 .04 .01 .78 .78 .82 .78 . 78 .78 109 On t h e PC a n d PR r a t i o n s t h e h e i f e r s w e r e l e s s e f f i c i e n t t h a n t h e > 2 n d l a c t a t i o n c o w s . H o w e v e r , o n t h e PS r a t i o n t h e r e was l i t t l e d i f f e r e n c e b e t w e e n t h e p e r f o r m a n c e o f t h e h e i f e r s a n d o l d e r c o w s . T h e ( T x B x L ) i n t e r a c t i o n a n d t h e c o v a r i a b l e w e r e s i g n i f i c a n t f o r m i l k / G . E . a n d m i l k / C P . T h e p r e d i c t e d means a n d s t a n d a r d e r r o r s f o r s i g n i f i c a n t s o u r c e s o f v a r i a t i o n s f o r t h e e f f i c i e n c y r a t i o s a r e p r e s e n t e d i n T a b l e s V I I I a n d IX o f t h e A p p e n d i x . d . B l o o d M e t a b o l i t e s B l o o d p l a s m a m e t a b o l i t e c o n c e n t r a t i o n s a t t h e e n d o f p e r i o d I I a r e shown i n T a b l e 32. T h e 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 b l o o d p l a s m a m e t a b o l i t e s a r e p r e s e n t e d i n T a b l e 33. 110 TABLE 32. PREDICTED MEAN PLASMA METABOLITE CONCENTRATIONS PERIOD II METABOLITE PC TREATMENT PS PR ORTHOGONAL CONTRAST (C) (S) VS. VS. (S+R) (R) (mg %) Glucose S.E. 64.6 1.18 67.4 1 .74 61 .5 3.80 NS NS (»/mole/l) NEFA S.E. 200.0 19.95 248.4 25.74 226.3 14.71 NS NS NS: Not s i g n i f i c a n t TABLE 33, COEFFICIENTS METABOLITES PERIOD II OF DETERMINATION FOR BLOOD DEGREES OF PLASMA PLASMA SOURCE OF VARIATION FREEDOM GLUCOSE NEFAS Treatment (T) 2 .08 .08 Breed (B) 1 .00 .01 L a c t a t i o n Category (L) 1 .12 .01 (TXB) I n t e r a c t i o n 2 .02 .02 (TXL) I n t e r a c t i o n 2 .04 .08 (BXL) I n t e r a c t i o n 1 .00 .16 (TXBXL) I n t e r a c t i o n 2 .00 .03 C o v a r i a b l e 1 .02 .00 (Days i n Period) T o t a l 26 .35 .34 S t a t i s t i c a l s i g n i f i c a n c e . *(P < .05), **(P < .01), 111 C. D i s c u s s i o n 1. P e r i o d I a . P r o t e c t e d T a l l o w S u p p l e m e n t s A c c o r d i n g t o t h e m a n u f a c t u r e r o f t h e p r o t e c t e d t a l l o w s u p p l e m e n t s ( A l t a L i p i d s C a n a d a L t d . ) , t h e d e g r e e o f i_n v i t r o p r o t e c t i o n f o r PROTEC S was 91 % w h i l e t h a t f o r PROTEC R was 81 % ( T a b l e 2 ) . T h e m e t h o d u s e d t o a s s e s s t h e p r o t e c t i o n i n v o l v e d t h e m e a s u r e m e n t o f t h e f r e e f a t t y a c i d c o n t e n t o f a s a m p l e , b e f o r e a n d a f t e r i n c u b a t i o n w i t h l i p a s e . H o w e v e r , t h i s d o e s n o t n e c e s s a r i l y mean t h a t t h e PROTEC S a n d PROTEC R s u p p l e m e n t s r e l e a s e d 9 a n d 19 % f r e e f a t , r e s p e c t i v e l y , i n t h e rumen, due t o t h e f a c t t h a t t h e r e i s p o o r a g r e e m e n t b e t w e e n i n v i t r o a n d in v i v o d e g r e e o f p r o t e c t i o n ( H o o d , 1 9 7 7 ) . Hood ( 1 9 7 7 ) r e p o r t e d a s i g n i f i c a n t d i f f e r e n c e among cows f e d t h e same p r o t e c t e d l i p i d i n t e r m s o f t h e c a l c u l a t e d _in v i v o d e g r e e o f p r o t e c t i o n . F u r t h e r , he s u g g e s t e d t h a t a l t h o u g h i_n v i t r o t e s t s a r e c o n v e n i e n t a n d f a s t , t h e y a p p e a r t o o v e r e s t i m a t e t h e in v i v o p r o t e c t i o n . S t o r r y e t a l . ( 1 9 8 0 ) a l s o r e p o r t e d a v e r y h i g h d e g r e e o f v a r i a b i l i t y among s a m p l e s w i t h in v i t r o t e s t s f o r d e g r e e o f p r o t e c t i o n o f p r o t e c t e d l i p i d s . I f t h e p r o t e c t i o n v a l u e s o f 91 % f o r PROTEC S a n d 81 % f o r PROTEC R r e p r e s e n t r e l a t i v e v a l u e s a t l e a s t , t h e n i t w o u l d be e x p e c t e d t h a t t h e PROTEC S r a t i o n s h o u l d e l i c i t a somewhat g r e a t e r r e s p o n s e t h a n t h e PROTEC R r a t i o n a s s u m i n g t h a t t h e e f f e c t ( s ) o f p r o t e c t e d t a l l o w i s ( a r e ) l i n e a r . I n f a c t , i t was 112 o b s e r v e d t h a t t h e PROTEC S t r e a t m e n t d i d p r o d u c e g r e a t e r r e s p o n s e s t h a n t h e PROTEC R t r e a t m e n t , b a s e d on s e v e r a l p r o d u c t i o n p a r a m e t e r s w h i c h w i l l be d i s c u s s e d s u b s e q u e n t l y . b . R a t i o n C o m p o s i t i o n When t h e p r e s e n t s t u d y was b e i n g d e s i g n e d , t h e c h e m i c a l a n a l y s e s f o r t h e p r o t e c t e d t a l l o w s u p p l e m e n t s w e r e n o t a v a i l a b l e . I t was r e p o r t e d by t h e s u p p l i e r t h a t t h e s u p p l e m e n t s w o u l d c o n t a i n a p p r o x i m a t e l y 34-38 % c r u d e f a t ( C F . ) a n d 22-26 % C P . . A c t u a l c h e m i c a l a n a l y s e s ( T a b l e 3) showed t h e PROTEC R s u p p l e m e n t c o n t a i n e d more C F . t h a n t h e PROTEC S, w h i c h a c c o u n t s i n p a r t , f o r t h e h i g h e r , E . E . c o n t e n t o f t h e PROTEC R c o n c e n t r a t e ( T a b l e 4 ) . c . I n t a k e s P r e d i c t e d means f o r d a i l y , p e r cow i n t a k e s o f d r y m a t t e r , e n e r g y a n d p r o t e i n a r e s u m m a r i z e d i n T a b l e 5. T o t a l d r y m a t t e r , G.E., D.E., C P . a n d D.P. i n t a k e s w e r e 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 > .05) w i t h p r o t e c t e d t a l l o w i n t h e r a t i o n s . H o w e v e r , t h e r e was a s l i g h t i n c r e a s e i n a l l t h e i n t a k e s w i t h t h e PROTEC S r a t i o n a n d a s l i g h t d e c r e a s e w i t h t h e PROTEC R r a t i o n when c o m p a r e d w i t h t h e c o n t r o l t r e a t m e n t . I n mo s t t r i a l s w i t h n o n - l a c t a t i n g a n i m a l s , D.M. i n t a k e d e c r e a s e d when p r o t e c t e d l i p i d s w ere f e d ( G a r r e t t e t a l . , 1976a; M c C a r t o r a n d S m i t h , 1 9 7 8 ) . W i t h l a c t a t i n g d a i r y c o w s , D.M. i n t a k e h a s g e n e r a l l y d e c r e a s e d w i t h p r o t e c t e d l i p i d i n t a k e s i n e x c e s s o f 1.7 k g / c o w / d a y ( M a c l e o d e t a l . , 1977; B i n e s e t a l . , 1978; S m i t h 113 e t a l . , 1 9 7 8 ) . On t h e o t h e r h a n d , t h e r e were no s i g n i f i c a n t d i f f e r e n c e s i n i n t a k e s b y cows f o r r a t i o n s c o n t a i n i n g l e s s t h a n 1.70 k g / c o w / d a y o f p r o t e c t e d t a l l o w ( B i n e s e_t a _ l . , 1978; Sharma e t a l . , 1978; K r o n f e l d e t a l . , 1 9 8 0 ) . T h i s i s i n k e e p i n g w i t h t h e p r e s e n t s t u d y w h e r e D.M. i n t a k e s were n o t s i g n i f i c a n t l y a f f e c t e d (P > .05) w i t h a n a v e r a g e p r o t e c t e d t a l l o w i n t a k e o f 0.95 k g / c o w / d a y . E n e r g y i n t a k e i n m o s t s t u d i e s w h e r e p r o t e c t e d t a l l o w was f e d t o l a c t a t i n g d a i r y c o w s , 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 > .05) w i t h o r w i t h o u t p r o t e c t e d t a l l o w ( M a c l e o d e t a l . , 1977; S m i t h e t a l . , 1978; K r o n f e l d e t a l . , 1 9 8 0 ) . A t l o w l e v e l s o f s u p p l e m e n t a t i o n w i t h a d 1 i b i t u r n i n t a k e , t h e r e h a v e s o m e t i m e s b e e n i n c r e a s e s i n e n e r g y i n t a k e ( S t o r r y e t a _ l . , 1 9 8 0 ) . T h i s i s c o n s i s t e n t w i t h t h e s m a l l i n c r e a s e i n e n e r g y i n t a k e o b s e r v e d w i t h t h e PROTEC S r a t i o n . C r u d e p r o t e i n i n t a k e s p a r a l l e l e d D.M. i n t a k e s i n most s t u d i e s . T h e r e were no s i g n i f i c a n t d i f f e r e n c e s b e t w e e n r a t i o n s w i t h o r w i t h o u t p r o t e c t e d l i p i d (P > .05) i n t e r m s o f p r o t e i n i n t a k e s when t h e i n t a k e o f p r o t e c t e d t a l l o w was l e s s t h a n 1.70 k g / c o w / d a y ( B i n e s e t a l . , 1978; Sharma e t a l . , 1978; K r o n f e l d e t a l . , 1 9 8 0 ) . A t i n t a k e s o f p r o t e c t e d t a l l o w i n e x c e s s o f 1.70 k g / c o w / d a y , t h e d e c r e a s e s i n D.M. i n t a k e were a c c o m p a n i e d by a d e c r e a s e i n p r o t e i n i n t a k e ( M a c l e o d e t a l . , 1977; B i n e s e t a l . , 1978; S m i t h e t a l . , 1 9 7 8 ) . The l i p i d s u p p l e m e n t s u s e d i n t h e p r e s e n t s t u d y w e r e n o t f u l l y p r o t e c t e d . T h e r e f o r e t h e e f f e c t s o f p r o t e c t e d t a l l o w on D.M., e n e r g y a n d p r o t e i n i n t a k e s h a v e b e e n c o n f o u n d e d by t h e 1 14 e f f e c t s o f f r e e f a t on rumen d i g e s t i o n . F r e e f a t h a s b e e n shown t o d e p r e s s D.M. i n t a k e ( P e r r y e t a _ l . , 1976; K o w a l c z y k e t a l . , 1977) a n d i t i s l i k e l y t h a t t h e l e s s w e l l p r o t e c t e d PROTEC R s u p p l e m e n t c o n t a i n e d a l e v e l o f f r e e f a t w h i c h i n t e r f e r e d w i t h rumen d i g e s t i o n , c a u s i n g a s l i g h t d e p r e s s i o n i n D.M. i n t a k e a n d c o n s e q u e n t l y e n e r g y a n d p r o t e i n i n t a k e s a s w e l l . T h e PROTEC S s u p p l e m e n t on t h e o t h e r h a n d , was w e l l e n o u g h p r o t e c t e d t o a l l o w s l i g h t i n c r e a s e s i n D.M., e n e r g y a n d p r o t e i n i n t a k e s . D r y m a t t e r , e n e r g y a n d p r o t e i n i n t a k e s w e r e h i g h e r f o r H o l s t e i n s t h a n f o r A y r s h i r e s a n d h i g h e r f o r > 2nd l a c t a t i o n cows t h a n f o r h e i f e r s ( T a b l e 6 a n d T a b l e I o f t h e A p p e n d i x ) . T h i s was t o be e x p e c t e d . F o r h o u s e d c a t t l e , a d l i b i t u m i n t a k e h a s b e e n shown t o be p r o p o r t i o n a l t o m e t a b o l i c s i z e ( B l a x t e r a n d W i l s o n , 1 9 6 2 ) . T h e H o l s t e i n s , on a v e r a g e , w e r e o f l a r g e r m e t a b o l i c b o d y s i z e t h a n t h e A y r s h i r e s , a n d t h e ^ 2 n d l a c t a t i o n cows w e r e l a r g e r t h a n t h e h e i f e r s . I n a s t u d y d e s i g n e d t o e x a m i n e t h e i n f l u e n c e o f d r y p e r i o d d i e t o n , among o t h e r t h i n g s , f e e d i n t a k e p o s t - p a r t u m , i t was f o u n d t h a t r e g a r d l e s s o f p r e -p a r t u m d i e t , t h e cows i n t h e > 2nd l a c t a t i o n c o n s u m e d more D.M. a t a l l s t a g e s o f t h e l a c t a t i o n (P < .001) t h a n t h e h e i f e r s ( J o h n s o n a n d O t t e r b y , 1 9 8 1 ) . B a s e d on D.M. i n t a k e s ( T a b l e 5) t h e d a i l y i n t a k e s o f D.E. a n d C P . w e r e more t h a n a d e q u a t e t o s u p p o r t t h e l e v e l s o f m i l k p r o d u c t i o n on t h e 3 t r e a t m e n t s (NRC, 1 9 7 8 ) . H o w e v e r , due t o t h e h i g h p r o p o r t i o n o f c o n c e n t r a t e s i n t h e c o m p l e t e r a t i o n , t h e minimum r e q u i r e m e n t o f 21 % ADF was n o t met. T h e c o n t r o l , PROTEC S a n d PROTEC R r a t i o n s c o n t a i n e d 17.3, 17.3 a n d 18.5 % 1 15 ADF, r e s p e c t i v e l y . A l l 3 r a t i o n s w o u l d t h e r e f o r e h a v e a d e p r e s s i n g e f f e c t on m i l k f a t %. d . A p p a r e n t D i g e s t i b i l i t i e s T h e r e w e r e no d i f f e r e n c e s b e t w e e n t h e c o n t r o l r a t i o n a n d t h e r a t i o n s c o n t a i n i n g p r o t e c t e d t a l l o w (P > .05) f o r a p p a r e n t d i g e s t i b i l i t i e s o f D.M., O.M., G.E., N, ADF, t o t a l a s h , C a , P o r Mg, a s shown i n T a b l e 7. I n a d d i t i o n , t h e r e w e r e no d i f f e r e n c e s b e t w e e n t h e PROTEC S a n d PROTEC R r a t i o n s (P > .05) f o r a n y o f t h e s e d i g e s t i b i l i t y c o e f f i c i e n t s . T h e a p p a r e n t d i g e s t i b i l i t y o f E . E . was s i g n i f i c a n t l y i n c r e a s e d (P < .01) w i t h r a t i o n s c o n t a i n i n g p r o t e c t e d t a l l o w . F u r t h e r m o r e , t h e PROTEC R r a t i o n p r o d u c e d a s i g n i f i c a n t l y h i g h e r E . E . a p p a r e n t d i g e s t i b i l i t y t h a n t h e PROTEC S r a t i o n (P < . 0 5 ) . S harma e_t a l . , ( 1 9 7 8 ) r e p o r t e d no s i g n i f i c a n t d i f f e r e n c e s (P > .05) b e t w e e n cows f e d a c o n t r o l r a t i o n a n d t h o s e f e d r a t i o n s c o n t a i n i n g 5, 10, o r 15 % s o y b e a n m e a l - p r o t e c t e d t a l l o w , w i t h r e s p e c t t o t h e a p p a r e n t d i g e s t i b i l i t y o f D.M., G.E., N, ADF, Ca o r Mg, a n d a s i g n i f i c a n t i n c r e a s e i n t h a t o f E . E . (P < . 0 5 ) . T h e r e s u l t s o f t h e p r e s e n t s t u d y c o n f i r m t h e s e o b s e r v a t i o n s . A p p a r e n t N d i g e s t i b i l i t y t e n d e d t o d e c r e a s e w i t h p r o t e c t e d t a l l o w ( T a b l e 7 ) , a l t h o u g h n o t s i g n i f i c a n t l y . B i n e s e t a l . ( 1 9 7 8 ) o b s e r v e d s i g n i f i c a n t d e c r e a s e s i n N d i g e s t i b i l i t y f o r c ows f e d p r o t e c t e d t a l l o w a t 2.78 k g / c o w / d a y o r g r e a t e r . T h e y n o t e d t h a t t h e amount o f e n e r g y d i g e s t e d i n t h e f o r m o f p r o t e i n was n e g a t i v e l y r e l a t e d t o t h e amount o f e n e r g y d i g e s t e d i n t h e 116 f o r m o f f a t t y a c i d s . I n t h e p r e s e n t s t u d y , t h e p r o t e c t e d t a l l o w i n t a k e was n o t h i g h e n o u g h t o c a u s e a n e g a t i v e e f f e c t on N d i g e s t i b i l i t y . S e v e r a l w o r k e r s h a v e r e p o r t e d t h a t t h e i n c l u s i o n o f l i p i d s i n t h e r a t i o n o f r u m i n a n t s c a u s e s a d e c r e a s e i n t h e a p p a r e n t d i g e s t i b i l i t y o f f i b r e ( K o w a l c z y k e t a _ l . , 1 9 7 7 ) . T h e a b s e n c e o f a n y d e c r e a s e i n a p p a r e n t d i g e s t i b i l i t y o f ADF s u g g e s t s t h e p r o t e c t e d t a l l o w s u p p l e m e n t s u s e d i n t h i s e x p e r i m e n t w e r e w e l l p r o t e c t e d . I t h a s b e e n f o u n d t h a t t h e d e p r e s s i o n i n f i b r e d i g e s t i b i l i t y s o m e t i m e s a s s o c i a t e d w i t h t h e f e e d i n g o f f r e e f a t s ( B i n e s e t a l . , 1978; K r o n f e l d a n d D o n o g h u e , 1980) c a n be r e v e r s e d by t h e a d d i t i o n o f m e t a l c a t i o n s , i n p a r t i c u l a r c a l c i u m ( P a l m q u i s t a n d J e n k i n s , 1 9 8 0 ) . I n t h e s t u d i e s o f K r o n f e l d a n d D o n o g h u e ( 1 9 8 0 ) a n d B i n e s e t a _ l . ( 1 9 7 8 ) , t h e d e c r e a s e d f i b r e d i g e s t i b i l i t i e s w e r e a s s o c i a t e d w i t h r e d u c e d d i g e s t i b i l i t i e s o f C a . When l i p i d s a r e a d d e d t o t h e r a t i o n t h e r e i s t h e p o t e n t i a l f o r s o a p f o r m a t i o n w h i c h may t i e up some o f t h e d i e t a r y m i n e r a l s a n d t h u s r e d u c e t h e i r a p p a r e n t d i g e s t i b i l i t i e s . T h e a b s e n c e o f a n e f f e c t o f p r o t e c t e d t a l l o w on t h e a p p a r e n t d i g e s t i b i l i t i e s o f t o t a l a s h , C a , P o r Mg ( T a b l e 5) i n d i c a t e s t h a t s o a p f o r m a t i o n was n o t a p r o b l e m w i t h t h e r a t i o n s f e d i n t h i s s t u d y . Sharma e t a l . ( 1 9 7 8 ) m e a s u r e d f a e c a l s o a p s a n d o b s e r v e d t h a t t h e y were n o t a f f e c t e d by p r o t e c t e d t a l l o w i n t h e d i e t (P > . 0 5 ) . T h e s i g n i f i c a n t i n c r e a s e i n a p p a r e n t d i g e s t i b i l i t y o f E . E . ( T a b l e 7) i s i n k e e p i n g w i t h t h e m a j o r i t y o f s t u d i e s w i t h 1 17 p r o t e c t e d l i p i d s ( M a c l e o d e t a l . , 1977; B i n e s e t a _ l . , 1978; K r o n f e l d a n d D o n o g h u e , 1 9 8 0 ) . I n c r e a s i n g t h e f a t i n t a k e d i m i n i s h e s t h e i m p a c t o f m e t a b o l i c f a e c a l f a t on a p p a r e n t d i g e s t i b i l i t y o f E . E . a n d c o u l d be i n v o l v e d i n t h e i n c r e a s e d E . E . a p p a r e n t d i g e s t i b i l i t y w i t h p r o t e c t e d t a l l o w . S i n c e t h e PROTEC R r a t i o n h a d a h i g h e r E . E . c o n t e n t t h a n t h e PROTEC S r a t i o n , i t f o l l o w s t h a t t h e f o r m e r c a u s e d a h i g h e r E . E . a p p a r e n t d i g e s t i b i l i t y . B i n e s e t a l . ( 1 9 7 8 ) showed t h a t t h e r e l a t i o n s h i p b e t w e e n amount o f t o t a l f a t t y a c i d d i g e s t e d a n d i n t a k e , was l i n e a r up t o an i n t a k e o f a p p r o x i m a t e l y 1.2 kg f a t t y a c i d s / c o w / d a y . T h e y s u g g e s t e d a t l e v e l s a b o v e 1.2 kg f a t t y a c i d s / c o w / d a y , t h e l i m i t o f t h e i n t e s t i n e ' s c a p a c i t y t o a b s o r b f a t t y a c i d a p p e a r e d t o h a v e b e e n e x c e e d e d e i t h e r due t o an u p p e r l i m i t f o r a b s o r p t i o n p e r s e , o r t o a n u p p e r l i m i t f o r l i p o l y s i s . I n t h e p r e s e n t s t u d y t h e E . E . c o n t e n t o f f a e c e s was h i g h e r on r a t i o n s w i t h p r o t e c t e d t a l l o w a s c o m p a r e d t o t h e c o n t r o l , i n d i c a t i n g a g r e a t e r o u t p u t o f f a t t y a c i d s w i t h p r o t e c t e d t a l l o w i n t h e d i e t . T h e E . E . % o f f a e c e s on t h e c o n t r o l , PROTEC S a n d PROTEC R r a t i o n s ( ± S . D . ) w e r e 2 . 1 ± . 1 6 , 2.31.21, a n d 2.61.40 %, r e s p e c t i v e l y . N e v e r t h e l e s s , t h e m a g n i t u d e o f t h e i n c r e a s e i n % E . E . o u t p u t w i t h r a t i o n s c o n t a i n i n g p r o t e c t e d t a l l o w was l e s s t h a n t h e m a g n i t u d e o f t h e i n c r e a s e i n a b s o r p t i o n o f t h e e t h e r e x t r a c t a b l e f r a c t i o n f r o m t h e g a s t r o - i n t e s t i n a l t r a c t . I t s h o u l d be p o i n t e d o u t t h a t t h e a b s e n c e o f a n e f f e c t on t h e d i g e s t i b i l i t y c o e f f i c i e n t s o f n o n - l i p i d c o m p o n e n t s i n t h e d i e t d o e s n o t n e c e s s a r i l y p r e c l u d e t h e i r r e d u c e d d i g e s t i o n i n t h e rumen b e c a u s e t h e r e may h a v e b e e n a c o m p e n s a t o r y i n c r e a s e i n 118 d i g e s t i o n i n the lower g a s t r o - i n t e s t i n a l t r a c t . I t would be necessary to cannulate experimental animals i n the rumen, the abomasum and t e r m i n a l ileum to gain some i n s i g h t i n t o t h i s problem. The standard e r r o r s a s s o c i a t e d with the d i g e s t i b i l i t y c o e f f i c i e n t s f o r the 7-day c o l l e c t i o n p e r i o d (Table 7) are not c o n s i s t e n t l y lower or higher than the standard e r r o r s a s s o c i a t e d with the apparent d i g e s t i b i l i t y c o e f f i c i e n t s f o r the 4-day c o l l e c t i o n p e r i o d (Table V of the Appendix). I t may be concluded, t h e r e f o r e , that the 7-day c o l l e c t i o n p e r i o d does not add any s i g n i f i c a n t degree of accuracy to the r e s u l t s and a 4-day c o l l e c t i o n p e r i o d i s e q u a l l y as good. e. U r i n a r y Nitrogen There was c o n s i d e r a b l e d i f f i c u l t y with the u r i n e c o l l e c t i o n method employed. The u r i n e volumes t h e r e f o r e represent the best estimates obtained based on the c o l l e c t i o n days when u r i n e l o s s e s were absent or minimal. For t h i s reason the data were not s u b j e c t e d to an a n a l y s i s of v a r i a n c e . 119 f , P r o d u c t i o n P a r a m e t e r s i . M i l k a n d M i l k E n e r g y P r e d i c t e d mean d a i l y , p e r cow o u t p u t s o f m i l k , FCM, SCM a n d m i l k G.E. a r e shown i n T a b l e 10. M i l k y i e l d / c o w / d a y was s i g n i f i c a n t l y i n c r e a s e d (P < .05) w i t h p r o t e c t e d t a l l o w , a s e x p e c t e d . O t h e r s t u d i e s w i t h c o m p a r a b l e i n t a k e s o f p r o t e c t e d t a l l o w h a v e d e m o n s t r a t e d m i l k y i e l d i n c r e a s e s o v e r t h e c o n t r o l s s i m i l a r t o t h o s e s e e n i n t h e p r e s e n t s t u d y . F o r e x a m p l e B i n e s et. a l . ( 1 9 7 8 ) r e p o r t e d an i n c r e a s e o f 3.9 k g / c o w / d a y i n a c o n t i n u o u s f e e d i n g t r i a l w i t h i n t a k e s o f 1.21 kg P T / c o w / d a y . S m a l l e r , n o n - s i g n i f i c a n t m i l k y i e l d i n c r e a s e s w e r e o b s e r v e d when s w i t c h - b a c k d e s i g n s h a v e b e e n u s e d ( S h a r m a e t a l . , 1 9 7 8 ) . I n t h e p r e s e n t s t u d y a c o n t i n u o u s f e e d i n g d e s i g n was c h o s e n o v e r a s w i t c h - b a c k d e s i g n f o r s e v e r a l r e a s o n s . I t h a s b e e n shown t h a t t h e r e s p o n s e , i n t e r m s o f m i l k y i e l d , t o i n c r e m e n t s o f f o o d , d e c l i n e s a s t h e l a c t a t i o n p r o c e e d s ( B r o s t e r e t a l . , 1969) . T h e r u m i n a n t h a s b o t h s h o r t - a n d l o n g - t e r m c o n t r o l s o f f e e d i n t a k e i n t h e r e g u l a t i o n o f e n e r g y b a l a n c e ( B a u m g a r d t , 1970) a n d a s w i t c h - b a c k d e s i g n w o u l d t e n d t o mask t h e e f f e c t s o f a n y t r e a t m e n t , d ue t o a c a r r y - o v e r e f f e c t o f t h e cow's o v e r a l l e n e r g y s t a t u s f r o m one p e r i o d t o t h e n e x t . I n a d d i t i o n t o m i l k y i e l d , FCM a n d SCM we r e m e a s u r e d ( T a b l e 1 0 ) . I n o r d e r t o make c o m p a r i s o n s b e t w e e n d i f f e r e n t v o l u m e s o f m i l k o f v a r y i n g c h e m i c a l c o m p o s i t i o n s , t h e y must f i r s t be c o n v e r t e d t o some common t e r m . The g r o s s e n e r g y ( o r 1 20 h e a t o f c o m b u s t i o n ) v a l u e r e p r e s e n t s t h e most common c h a r a c t e r i s t i c t o w h i c h a l l o r g a n i c s u b s t a n c e s c a n be r e d u c e d ( T y r e l l a n d R e i d , 1 9 6 5 ) . H o w e v e r , i t s d i r e c t m e a s u r e m e n t i s c o s t l y . T h e e n e r g y c o n t e n t o f m i l k c a n be e s t i m a t e d f r o m p r e d i c t i o n e q u a t i o n s b a s e d on one o r more o f t h e c o m p o n e n t s o f m i l k . G a i n e s ( 1 9 2 8 ) p r o p o s e d t h e u s e o f FCM a s t h e b a s i s o f e q u a t i n g m i l k o u t p u t s . R e c o g n i z i n g t h a t c h a n g e s i n m i l k c o m p o s i t i o n c o u l d r e d u c e t h e a c c u r a c y w i t h w h i c h t h e FCM e q u a t i o n w i l l a d j u s t t h e y i e l d t o a v o l u m e o f m i l k o f c o n s t a n t e n e r g y v a l u e , T y r e l l a n d R e i d ( 1 9 6 5 ) d e r i v e d p r e d i c t i o n e q u a t i o n s f o r m i l k e n e r g y b a s e d on t h e c h e m i c a l l y a n a l y z e d m i l k c o m p o n e n t s i n 600 s a m p l e s o f H o l s t e i n m i l k . T h e y c o n c l u d e d t h a t t h e b e s t e s t i m a t e o f m i l k e n e r g y was o b t a i n e d f r o m t h e f o l l o w i n g e q u a t i o n ( E q u a t i o n 5 ) : E = 41.63 (% f a t ) + 2 4 . 1 3 ( % p r o t e i n ) + 21 . 6 0 ( % l a c t o s e ) - 11.72 ( E q . 5) w h e r e : E = g r o s s e n e r g y v a l u e ( k c a l / l b o f m i l k ) . FCM y i e l d was s i g n i f i c a n t l y i n c r e a s e d ( T a b l e 10) w i t h p r o t e c t e d t a l l o w , a f i n d i n g w h i c h i s c o n s i s t e n t w i t h v i r t u a l l y a l l t r i a l s w i t h p r o t e c t e d t a l l o w f e d a t a n y l e v e l ( M a c l e o d e t a l . , 1977; S h a r m a e t a l . , 1978; S m i t h e t a l . , 1978; F i s h e r , 1 9 7 9 ) . S i n c e m i l k y i e l d was s i g n i f i c a n t l y i n c r e a s e d (P < .05) a n d m i l k f a t % ( T a b l e 11) 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 121 (P > .05) w i t h p r o t e c t e d l i p i d s , i t f o l l o w s t h a t FCM s h o u l d i n c r e a s e . S o l i d s - c o r r e c t e d m i l k s h o w e d an i n c r e a s i n g t r e n d w i t h p r o t e c t e d t a l l o w t r e a t m e n t s b u t i t was n o t s i g n i f i c a n t l y i n c r e a s e d o v e r t h e c o n t r o l (P > . 0 5 ) . F r o m t h e e q u a t i o n u s e d t o p r e d i c t SCM ( E q u a t i o n 6) ( T y r e l l a n d R e i d , 1965) one c a n s e e t h a t t h e m i l k p r o t e i n %, w h i c h was s i g n i f i c a n t l y d e c r e a s e d (P < .01) w i t h p r o t e c t e d t a l l o w r a t i o n s , p r e v e n t e d t h e SCM y i e l d i n c r e a s e f r o m r e a c h i n g s i g n i f i c a n c e . SCM = M Y(43.63 x F + 24.13 x P + 21.60 x L - 11.72) ( E q . 6) w h e r e : MY = m i l k y i e l d F = m i l k f a t % P = m i l k p r o t e i n % L = m i l k l a c t o s e % M a c l e o d e t a l . ( 1 9 7 7 ) r e p o r t e d i n c r e a s e s i n SCM w i t h p r o t e c t e d t a l l o w d i e t s , w h i c h w e r e s i g n i f i c a n t (P < .05) i n some c a s e s b u t w h i c h d i d n o t r e a c h s i g n i f i c a n c e i n o t h e r s due t o d e p r e s s i o n s i n m i l k p r o t e i n a n d l a c t o s e %. M i l k G.E., l i k e SCM, i n c r e a s e d w i t h p r o t e c t e d t a l l o w d i e t s b u t t h i s i n c r e a s e was n o t s i g n i f i c a n t (P > . 0 5 ) . B i n e s e t a l . ( 1 9 7 8 ) r e p o r t e d t h a t a s i g n i f i c a n t c u r v i l i n e a r r e l a t i o n s h i p e x i s t e d b e t w e e n m i l k e n e r g y p r o d u c t i o n a n d l e v e l o f f a t t y a c i d s d i g e s t e d , when p r o t e c t e d t a l l o w was f e d t o l a c t a t i n g d a i r y c o w s . T h e r e s p o n s e i n y i e l d s o f m i l k e n e r g y a n d m i l k c o m p o n e n t s was p o s i t i v e u n t i l t h e p r o p o r t i o n o f d i g e s t e d e n e r g y i n t h e f o r m o f f a t t y a c i d s was i n c r e a s e d t o 19 %. A f t e r t h i s p o i n t t h e d i g e s t i o n o f t o t a l e n e r g y f r o m t h e d i e t was r e d u c e d ( B i n e s 122 e t a l . , 1 9 7 8 ) . H o l s t e i n s p r o d u c e d more m i l k , FCM, SCM a n d m i l k G.E. t h a n t h e A y r s h i r e s a n d t h e > 2nd l a c t a t i o n cows p r o d u c e d more m i l k t h a n t h e h e i f e r s . L a r g e r b r e e d s n a t u r a l l y a r e c a p a b l e o f p r o d u c i n g h i g h e r o u t p u t s o f m i l k t h a n s m a l l e r b r e e d s ( G a u n t , 1 9 7 3 ) . S e c o n d l y , i t h a s b e e n shown t h a t m i l k y i e l d i n c r e a s e s w i t h a g e a t a n e v e r d e c l i n i n g r a t e u n t i l m a t u r i t y i s r e a c h e d ( G a c u l a e t a l . , 1 9 6 5 ) . i i . M i l k C o m p o s i t i o n M i l k f a t % i n c r e a s e d w i t h PROTEC S a n d d e c r e a s e d w i t h PROTEC R, r e l a t i v e t o t h e c o n t r o l r a t i o n , b u t t h e s e d i f f e r e n c e s w e r e n o t s i g n i f i c a n t (P > .05) ( T a b l e 1 1 ) . M i l k f a t y i e l d s i g n i f i c a n t l y i n c r e a s e d w i t h p r o t e c t e d t a l l o w (P < .05) ( T a b l e 1 1 ) . I n m o s t t r i a l s w h e r e t h e i n t a k e o f p r o t e c t e d t a l l o w was l e s s t h a n 1.70 k g / c o w / d a y , t h e r e was no s i g n i f i c a n t i n c r e a s e i n m i l k f a t % (P > .05) a l t h o u g h m i l k f a t % a l w a y s i n c r e a s e d ( B i n e s e t a l . , 1978; Sharma e t a l . , 1978; F i s h e r , 1979, K r o n f e l d e t a l . , 1980) . Due t o t h e f a c t t h a t t h e f a t t y a c i d p r o f i l e o f t h e m i l k i n t h e p r e s e n t s t u d y was n o t d e t e r m i n e d , i t c a n o n l y be p o s t u l a t e d what h a p p e n e d t o m i l k f a t s y n t h e s i s when p r o t e c t e d t a l l o w was f e d . M i l k f a t i s made up o f a p p r o x i m a t e l y 10 % s h o r t - c h a i n f a t t y a c i d s , 40 % l o n g - c h a i n f a t t y a c i d s a n d 50 % i n t e r m e d i a t e c h a i n l e n g t h f a t t y a c i d s ( S u t t o n , 1 9 8 0 ) . The s h o r t - c h a i n f a t t y a c i d s a s w e l l a s some o f t h e i n t e r m e d i a t e - c h a i n l e n g t h f a t t y a c i d s a r e s y n t h e s i z e d i n t h e mammary g l a n d a n d t h e b a l a n c e o f 123 t h e i n t e r m e d i a t e a n d a l l o f t h e l o n g - c h a i n f a t t y a c i d s a r e d e r i v e d m a i n l y f r o m t h e b l o o d p l a s m a t r i g l y c e r i d e s ( S t o r r y , 1 9 8 0 ) . M i l k ' f a t i s d e r i v e d f r o m t h r e e m a i n g r o u p s o f p r e c u r s o r s : a c e t i c a c i d a n d b u t y r i c a c i d a b s o r b e d f r o m t h e rumen a n d t o a much l e s s e r e x t e n t f r o m t h e c a e c u m ; l o n g e r - c h a i n f a t t y a c i d s m a i n l y a b s o r b e d f r o m t h e s m a l l i n t e s t i n e ; a n d a c e t a t e a n d l o n g e r - c h a i n f a t t y a c i d s d e r i v e d f r o m e n d o g e n o u s s o u r c e s ( S u t t o n , 1 9 8 0 ) . T h e d i e t , t h e r e f o r e c a n a f f e c t m i l k f a t s e c r e t i o n e i t h e r d i r e c t l y , by m o d i f y i n g t h e a m o u n t s o f p r e c u r s o r s a b s o r b e d f r o m t h e g a s t r o i n t e s t i n a l t r a c t , o r i n d i r e c t l y by m o d i f y i n g t h e way i n w h i c h t h e s e m i l k f a t p r e c u r s o r s a r e m e t a b o l i z e d i n t h e b o d y . T h e n e t e f f e c t o f a p r o t e c t e d l i p i d on m i l k f a t % a n d y i e l d i s t h e sum o f many i n t e r r e l a t e d f a c t o r s , e a c h o f w h i c h must be e x p l a i n e d i n t u r n . I t h a s b e e n d e m o n s t r a t e d t h a t a s t h e a c e t a t e : p r o p i o n a t e r a t i o d e c r e a s e s , s o d o e s m i l k f a t % ( S e i n e r a n d S h u l t z , 1 9 8 0 ) . I n t h e p r e s e n t s t u d y , a d e c r e a s e i n t h e m o l a r p e r c e n t a g e o f a c e t i c a c i d i n t h e rumen was o b s e r v e d w i t h a n i n c r e a s e d m o l a r p e r c e n t a g e o f p r o p i o n i c a c i d . T h e r e s u l t was a d e c r e a s e i n t h e a c e t a t e : p r o p i o n a t e r a t i o . F r e e l i p i d s h a v e c l e a r l y b e e n shown t o c a u s e r e d u c t i o n s i n t h e y i e l d s o f C6-C16 f a t t y a c i d s i n m i l k (Brumby e t a l . , 1972; B a n k s e t a l . , 1 976; G o e r i n g et. a l . , 1 9 7 7 ) . S i n c e t h e p r o t e c t e d t a l l o w f e d i n t h i s s t u d y was n o t 100 % p r o t e c t e d , t h e r e w o u l d h a v e b e e n a c e r t a i n amount o f f r e e l i p i d p r e s e n t i n t h e rumen. A s h o r t a g e o f a c e t a t e a n d 0-OH b u t y r a t e , t h e p r e c u r s o r s f o r s h o r t a n d i n t e r m e d i a t e c h a i n f a t t y a c i d s , c o u l d be r e s p o n s i b l e 124 f o r t h e r e d u c e d y i e l d s o f C6-C16 f a t t y a c i d s o b s e r v e d when f r e e f a t s a r e p r e s e n t i n t h e rumen ( S t o r r y , 1 9 7 0 ) . A s e c o n d e x p l a n a t i o n f o r t h e r e d u c e d s y n t h e s i s o f C 6 - C 1 6 f a t t y a c i d s i s t h a t l o n g - c h a i n f a t t y a c i d s i n t h e d i e t h a v e b e e n shown t o h a v e an i n h i b i t o r y e f f e c t on t h e a c t i v i t y o f a c e t y l CoA c a r b o x y l a s e ( B a r t l e y e t a l . , 1 9 6 7 ) . A c e t y l CoA c a r b o x y l a s e i s r e q u i r e d f o r t h e c o n v e r s i o n o f a c e t y l CoA t o m a l o n y l CoA, t h e r a t e - l i m i t i n g s t e p o f t h e m a l o n y l p a t h w a y f o r t h e s y n t h e s i s o f f a t t y a c i d s c o n t a i n i n g up t o 16 c a r b o n a t o m s . I n a d d i t i o n t o t h e r e d u c e d p r o d u c t i o n o f a c e t i c a c i d i n t h e rumen, P a l m q u i s t a n d J e n k i n s ( 1 9 8 0 ) s u g g e s t e d t h e h i g h e r l e v e l s o f p r o p i o n i c a c i d p r o d u c e d i n t h e rumen i n d u c e a g l u c o g e n i c r e s p o n s e o f a d i p o s e t i s s u e , c a u s i n g i t t o c o m p e t e w i t h t h e mammary g l a n d f o r a c e t a t e a n d l o n g - c h a i n f a t t y a c i d s . F r e e l i p i d s i n t h e rumen d e c r e a s e i n t r a r u m i n a l s y n t h e s i s o f f a t t y a c i d s , t h u s r e d u c i n g t h e a m o u n t s o f s t e a r i c a n d p a l m i t i c a c i d s , o f m i c r o b i a l o r i g i n a v a i l a b l e i n t h e s m a l l i n t e s t i n e f o r a b s o r p t i o n ( S t o r r y , 1 9 8 0 ) . S t u d i e s w i t h p r o t e c t e d p o l y u n s a t u r a t e d f a t t y a c i d s h a v e i n d i c a t e d t h a t t h e r e i s a t r a n s f e r o f a s much a s 40 % o f t h e d i e t a r y l o n g - c h a i n f a t t y a c i d s r e a c h i n g t h e i n t e s t i n e f r o m p r o t e c t e d l i p i d s , d i r e c t l y t o t h e m i l k ( C o o k e t al., 1 9 7 2 ) . F a t t y a c i d s ( f o r e x a m p l e , C 1 8 : 2 ) a r e a b s o r b e d f r o m t h e s m a l l i n t e s t i n e a n d a r e r e - e s t e r i f i e d t o f o r m t r i g l y c e r i d e s i n t h e c h y l o m i c r a o f l y m p h a n d p l a s m a ( R o b i n s o n , 1 9 7 0 ) . D u r i n g p a s s a g e t h r o u g h t h e c a p i l l a r y b e d o f t h e mammary g l a n d , t h e p l a s m a t r i g l y c e r i d e s a r e h y d r o l y z e d by l i p o p r o t e i n l i p a s e a n d t h e f a t t y 125 a c i d s a r e a b s o r b e d i n t o t h e i n t r a c e l l u l a r s p a c e s o f t h e mammary t i s s u e a n d a r e i n c o r p o r a t e d i n t o m i l k t r i g l y c e r i d e s ( B a r r y e t a l . , 1963; S t o r r y a n d Rook, 1 9 6 4 ) . T h i s a c c o u n t s f o r t h e p a r a l l e l c h a n g e s o b s e r v e d i n t h e p r o p o r t i o n s o f t h e l o n g - c h a i n f a t t y a c i d s i n t h e t r i g l y c e r i d e s o f p l a s m a a n d m i l k (Cook e t a l . , 1 9 7 2 ) . Th e d e c r e a s e i n t h e i n t r a m a m m a r y s y n t h e s i s o f f a t t y a c i d s may t h e r e f o r e be j u s t more t h a n c o m p e n s a t e d f o r by t h e d i r e c t t r a n s f e r o f d i e t a r y f a t t y a c i d s t o m i l k i n t h e c a s e o f t h e PROTEC S t r e a t m e n t . S i m i l a r l y t h e d e p r e s s i o n i n t h e i n t r a m a m m a r y s y n t h e s i s o f C6-C16 f a t t y a c i d s may be s l i g h t l y g r e a t e r t h a n t h e i n c r e a s e i n m i l k f a t due t o t r a n s f e r f r o m d i e t a r y f a t t y a c i d s on t h e PROTEC R t r e a t m e n t . L i k e l y t h e PROTEC R, w h i c h was o n l y 81 % p r o t e c t e d , r e l e a s e d more f r e e f a t i n t h e rumen t h a n d i d t h e PROTEC S, w h i c h was 91 % p r o t e c t e d a n d t h e i n h i b i t i o n o f i n t r a m a m m a r y f a t t y a c i d s y n t h e s i s was t h e r e f o r e g r e a t e r w i t h PROTEC R. H o l s t e i n s p r o d u c e d m i l k o f l o w e r f a t t e s t t h a n t h e A y r s h i r e s 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 b e t w e e n t h e b r e e d s i n m i l k f a t y i e l d (P > . 0 5 ) . T h e s e r e s u l t s a r e i n k e e p i n g w i t h known b r e e d d i f f e r e n c e s b e t w e e n H o l s t e i n s a n d A y r s h i r e s f o r m i l k f a t % a n d b r e e d s i m i l a r i t i e s f o r m i l k f a t y i e l d ( G a u n t , 1 9 7 3 ) . The £ 2nd l a c t a t i o n cows p r o d u c e d m i l k o f l o w e r f a t % p r o b a b l y b e c a u s e t h e i r m i l k y i e l d was s o much h i g h e r t h a n t h a t o f t h e h e i f e r s ( 3 2 . 0 4 v s . 20.58 k g / c o w / d a y ) . The o l d e r cows d i d a c t u a l l y p r o d u c e s i g n i f i c a n t l y more (P < .05) m i l k f a t t h a n t h e h e i f e r s b u t t h e e f f e c t o f t h e g r e a t i n c r e a s e 126 i n m i l k y i e l d was t o d i l u t e o r l o w e r t h e f a t t e s t . T h e s i g n i f i c a n t l y h i g h e r f a t % f o r A y r s h i r e h e i f e r s ( 4 . 0 5 %) o v e r o t h e r cows c a n be a t t r i b u t e d t o t h e c o n s i d e r a b l y l o w e r p r e d i c t e d m i l k y i e l d f o r t h e s e h e i f e r s ( 1 6 . 3 4 v s . 29.63 k g / d a y f o r a l l o t h e r c o w s ) . M i l k p r o t e i n % s i g n i f i c a n t l y d e c r e a s e d (P < .01) w i t h p r o t e c t e d t a l l o w . I n t h e m a j o r i t y o f c a s e s , p r o t e c t e d t a l l o w f e e d i n g h a s c a u s e d a d e p r e s s i o n i n m i l k p r o t e i n % ( D u n k l e y e t a l . , 1977; M a c l e o d e t a l . , 1977; B i n e s e t a l . , 1978; S h a r ma e t a l . , 1978; F i s h e r , 1 9 7 9 ) . R e s p o n s e s i n m i l k p r o t e i n y i e l d on t h e o t h e r h a n d h a v e b e e n v a r i a b l e a n d h a v e i n c r e a s e d when t h e i n c r e a s e i n m i l k y i e l d h a s b e e n g r e a t e n o u g h t o o v e r c o m e t h e d e p r e s s e d m i l k p r o t e i n %. T h e m a i n n i t r o g e n o u s c o n s t i t u e n t s i n m i l k i n c l u d e m i l k p r o t e i n s ( a , p, a n d K - c a s e i n , a - l a c t a l b u m i n a n d p - l a c t o g l o b u l i n ) w h i c h a r e s y n t h e s i z e d i n t h e mammary g l a n d a n d s e r u m p r o t e i n s a n d n o n - p r o t e i n n i t r o g e n c o m p o u nds ( p r i n c i p a l l y u r e a ) w h i c h a r e d e r i v e d f r o m t h e b l o o d ( Thomas, 1 9 8 0 ) . C o r r e l a t i o n s e x i s t b e t w e e n t h e c o n c e n t r a t i o n s o f u r e a i n m i l k a n d i n b l o o d p l a s m a a n d a l s o b e t w e e n m i l k n o n - p r o t e i n n i t r o g e n c o n t e n t a n d d i e t a r y p r o t e i n i n t a k e . H o w e v e r , t h e c o m p o s i t i o n o f t h e m i x t u r e s s e c r e t e d i n m i l k i s i n d e p e n d e n t o f d i e t (Thomas, 1980; Thomas e t a l . , 1 9 8 0 ) . T h e e f f e c t s on m i l k p r o t e i n o f b y - p a s s e d o r p o s t - r u m i n a l l y a d m i n i s t e r e d a m i n o a c i d s h a v e b e e n v a r i a b l e ( F i s h e r , 1969; F i s h e r , 1 9 7 2 ) . R e s u l t s o f p o s t - r u m i n a l i n f u s i o n t r i a l s s u g g e s t t h a t b y - p a s s i n g rumen f e r m e n t a t i o n w i t h a m i n o a c i d s i n c r e a s e s 127 b o t h m i l k p r o t e i n y i e l d a n d % ( C l a r k , 1 9 7 5 ) . R e s u l t s w i t h p o s t -r u m i n a l l y a d m i n i s t e r e d c a s e i n h a v e b e e n c o n s i s t e n t , g e n e r a l l y i n c r e a s i n g m i l k y i e l d , m i l k p r o t e i n y i e l d a n d m i l k p r o t e i n p e r c e n t a g e ( B r o d e r i c k e t a _ l . , 1970; V i k - M o e t a _ l . , 1974; C l a r k , 1975; Schwab e t a l . , 1 9 7 6 ) . I n l i g h t o f t h e s e o b s e r v a t i o n s on p r o t e c t e d p r o t e i n s , t h e d e c r e a s e i n m i l k p r o t e i n % c a u s e d by p r o t e c t e d l i p i d s i n t h i s a n d o t h e r s t u d i e s i s u n e x p e c t e d . One p o i n t w i t h r e g a r d t o t h e a p p l i c a b i l i t y o f f i n d i n g s f r o m s t u d i e s i n v o l v i n g p o s t - r u m i n a l a d m i n i s t r a t i o n o f a m i n o a c i d s o r p r o t e i n s i s t h a t S i d h u a n d A s h e s ( 1 9 7 7 ) f o u n d t h a t t y r o s i n e , a n a m i n o a c i d e s s e n t i a l f o r t h e s y n t h e s i s o f m i l k p r o t e i n s , may be d e s t r o y e d by f o r m a l d e h y d e d u r i n g p r o d u c t i o n o f p r o t e c t e d o i l s e e d s u p p l e m e n t s . I t i s p o s s i b l e , t h e r e f o r e , t h a t r e s p o n s e s t o p r o t e c t e d p r o t e i n s o r a m i n o a c i d s may n o t be t h e same a s t h e r e s p o n s e s t o t h e p r o t e c t e d p r o t e i n p o r t i o n o f a p r o t e c t e d l i p i d . F r e e f a t h a s b e e n shown t o r e d u c e m i l k p r o t e i n s y n t h e s i s ( S t o r r y e t a _ l . , 1974a; B a n k s e t a _ l . , 1976) a n d c o u l d c a n c e l o u t a n y i n c r e a s e s i n m i l k p r o t e i n y i e l d w h i c h may h a v e b e e n c a u s e d by b y - p a s s e d p r o t e i n s r e a c h i n g t h e s m a l l i n t e s t i n e . D u n k l e y e t a l . ( 1 9 7 7 ) r e p o r t e d t h a t p r o t e c t e d t a l l o w c a u s e d a s i g n i f i c a n t d e c r e a s e (P < .05) s p e c i f i c a l l y i n m i l k c a s e i n s w h i c h a r e t h o s e m i l k p r o t e i n s s y n t h e s i z e d w i t h i n t h e mammary g l a n d . F e e d i n g p r o t e c t e d t a l l o w i n t h i s s t u d y , i n a d i e t w h e r e t h e p r o t e c t e d t a l l o w r e p l a c e d some o f t h e b a r l e y a n d s o y b e a n m e a l , c o u l d h a v e c a u s e d a r e d u c e d m i c r o b i a l g r o w t h d u e t o t h e i n h i b i t o r y e f f e c t o f f r e e f a t a s w e l l a s a d e c r e a s e i n 128 c a r b o h y d r a t e a v a i l a b l e f o r f e r m e n t a t i o n , w i t h t h e n e t r e s u l t o f d e c r e a s e s i n 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 ( D u n k l e y e t a _ l . , 1977) a n d t h e a v a i l a b i l i t y o f g l u c o s e p r e c u r s o r s t o t h e cow ( S m i t h e t a l . , 1 9 7 8 ) . S i n c e g l u c o s e i s a m a j o r s o u r c e o f e n e r g y i n a d d i t i o n t o a c e t a t e , f o r m i l k p r o t e i n s y n t h e s i s , t h e d e c r e a s e i n m i l k p r o t e i n % m i g h t be due t o r e s t r i c t e d a v a i l a b i l i t y o f g l u c o s e ( S m i t h ejt a _ l . , 1 9 7 8 ) . I n t h i s s t u d y t h e r e was no r e d u c t i o n i n b l o o d g l u c o s e when p r o t e c t e d t a l l o w was f e d . The r e d u c e d m o l a r % o f a c e t a t e a n d t h e r e d u c e d a c e t a t e t p r o p i o n a t e r a t i o c a u s e d by f e e d i n g p r o t e c t e d t a l l o w ( T a b l e 23) r e p r e s e n t a d e c r e a s e i n t h e a c e t a t e a v a i l a b l e t o p r o v i d e e n e r g y f o r m i l k p r o t e i n s y n t h e s i s . H o l s t e i n s p r o d u c e d s i g n i f i c a n t l y more m i l k p r o t e i n t h a n A y r s h i r e s s i m p l y due t o a s i g n i f i c a n t l y h i g h e r m i l k y i e l d . A g a i n , t h e h i g h e r p r o t e i n y i e l d w i t h > 2nd l a c t a t i o n cows v e r s u s h e i f e r s was r e l a t e d t o m i l k y i e l d a s t h e r e w e r e no s i g n i f i c a n t d i f f e r e n c e s b e t w e e n b r e e d s o r l a c t a t i o n c a t e g o r i e s f o r m i l k p r o t e i n %. T h e r e was no s i g n i f i c a n t e f f e c t o f p r o t e c t e d t a l l o w on m i l k l a c t o s e % o r y i e l d , i n k e e p i n g w i t h t h e f i n d i n g s o f o t h e r s ( B i n e s e t a l . , 1978; S m i t h e t a l . , 1 9 7 8 ) . 129 g . E f f i c i e n c y R a t i o s i . E n e r g y T h e c o n v e r s i o n e f f i c i e n c y r a t i o s p r e s e n t e d i n T a b l e s 23 a n d 24 i n d i c a t e d t h a t p r o t e c t e d t a l l o w p r o d u c e d i n c r e a s e s i n e f f i c i e n c y o f c o n v e r s i o n o f e n e r g y t o m i l k , FCM, SCM a n d m i l k e n e r g y o f 20-24 %. E f f i c i e n c i e s m e a s u r e d f o r l a c t a t i n g cows by o t h e r w o r k e r s h a v e b e e n i n t h e r a n g e o f 8-14 % ( S m i t h e t a l . , 1978; K r o n f e l d e t a l . , 1 9 8 0 ) . Brumby e t a l . ( 1 9 7 8 ) d e t e r m i n e d t h a t i n c r e a s i n g t h e amount o f f a t t y a c i d d i g e s t e d u p t o a b o u t 30 M J / d a y , i m p r o v e d t h e p a r t i a l e f f i c i e n c y o f p r o d u c t i o n . T h e p r o b a b l e r e a s o n f o r t h i s i m p r o v e d e f f i c i e n c y o f p r o d u c t i o n w i t h p r o t e c t e d l i p i d s i s t h a t i n a d d i t i o n t o i n c r e a s i n g t h e e n e r g y d e n s i t y o f t h e d i e t , l o n g - c h a i n f a t t y a c i d s a r e m e t a b o l i z e d more e f f i c i e n t l y t h a n a r e v o l a t i l e f a t t y a c i d s , t h e m a j o r f o r m o f d i g e s t i b l e e n e r g y n o r m a l l y a v a i l a b l e t o r u m i n a n t s ( B l a x t e r , 1 9 7 1 ) . D i r e c t i n c o r p o r a t i o n o f d i e t a r y f a t t y a c i d s i n t o m i l k a n d a d i p o s e t i s s u e a s w e l l a s t h e i r o x i d a t i o n t o y i e l d ATP, c o n t r i b u t e t o t h e i n c r e a s e d e f f i c i e n c y o f e n e r g y u s e ( S t o r r y , 1980) . T h e f a c t t h a t t h e ^ 2 n d l a c t a t i o n cows w e r e more e f f i c i e n t m i l k p r o d u c e r s t h a n t h e h e i f e r s c a n be a t t r i b u t e d t o t h e f a c t t h a t t h e h e i f e r s w e r e g r o w i n g a t a g r e a t e r r a t e t h a n t h e o l d e r cows a n d w e r e r e q u i r e d t o p a r t i t i o n more e n e r g y f o r t h i s p u r p o s e . E f f i c i e n c y r a t i o s were n o t c o r r e c t e d f o r b o d y w e i g h t c h a n g e s . 130 i i . P r o t e i n P r o t e i n e f f i c i e n c y r a t i o s f o l l o w e d t h e e n e r g y r a t i o s a s w o u l d be e x p e c t e d b e c a u s e t h e r e w e r e no s i g n i f i c a n t d i f f e r e n c e s among t r e a t m e n t s f o r p r o t e i n o r d i g e s t i b l e p r o t e i n i n t a k e s (P > . 0 5 ) . h . A v e r a g e D a i l y G a i n A l t h o u g h t h e r e were no s i g n i f i c a n t d i f f e r e n c e s (P > .05) among t r e a t m e n t s f o r a v e r a g e d a i l y g a i n , i t i s i n t e r e s t i n g t o n o t e t h a t a s m i l k y i e l d , m i l k f a t y i e l d a n d t h e p r o p i o n a t e / a c e t a t e r a t i o i n c r e a s e d , t h e r e was a d e c r e a s i n g t r e n d i n A.D.G.. T h i s w o u l d s u g g e s t t h a t t h e cows w h i c h were p r o d u c i n g more m i l k e n e r g y w e r e p a r t i t i o n i n g l e s s e n e r g y t o b o d y w e i g h t i n c r e a s e s . B r e e d was t h e o n l y e f f e c t w h i c h was s i g n i f i c a n t f o r A.D.G. (P < . 0 5 ) . T h e H o l s t e i n s g a i n e d more w e i g h t / d a y t h a n d i d t h e A y r s h i r e s l i k e l y d u e t o t h e f a c t t h a t 80 % o f t h e H o l s t e i n s were h e i f e r s w h i l e o n l y 33 % o f t h e A y r s h i r e s w e r e h e i f e r s . A l s o t h e same % i n c r e a s e i n b o d y w e i g h t f o r a H o l s t e i n w o u l d r e p r e s e n t a l a r g e r a c t u a l w e i g h t i n c r e a s e t h a n w o u l d t h e same % i n c r e a s e f o r an A y r s h i r e . 131 i . B l o o d M e t a b o l i t e s T h e r e was no e f f e c t o f p r o t e c t e d t a l l o w on b l o o d g l u c o s e (P > .05) i n a g r e e m e n t w i t h t h e m a j o r i t y o f s t u d i e s ( M a c l e o d e t a l . , 1977; B i n e s e t a l . , 1978; C h r i s t e n s e n e t a l . , 1978; S m i t h et_ a _ l . , 1 9 7 8 ) . T h e h i g h e r p l a s m a g l u c o s e c o n c e n t r a t i o n o f h e i f e r s a s c o m p a r e d w i t h > 2nd l a c t a t i o n cows i s c o n s i s t e n t w i t h s t u d i e s o f S h a f f e r e t a l . ( 1 9 8 1 ) who f o u n d a n e g a t i v e c o r r e l a t i o n b e t w e e n a g e o f d a i r y cow a n d b l o o d g l u c o s e c o n c e n t r a t i o n . NEFA c o n c e n t r a t i o n s were r e a d a g a i n s t a p a l m i t i c a c i d s t a n d a r d c u r v e . S i n c e 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 e x t i n c t i o n a n d t h e c o n c e n t r a t i o n f o r a l l l o n g - c h a i n f a t t y a c i d s i s s l i g h t l y d i f f e r e n t , f o r t h e b e s t a c c u r a c y , when d e a l i n g w i t h a n y s i n g l e a c i d a c a l i b r a t i o n s h o u l d be made w i t h s u i t a b l e s t a n d a r d s . H o w e v e r , when a m i x t u r e o f l o n g - c h a i n a c i d s i s b e i n g i n v e s t i g a t e d , a s w i t h t h e NEFA i n b l o o d , i t i s n e c e s s a r y t o r e f e r r e a d i n g s t o a c a l i b r a t i o n l i n e made f r o m s t a n d a r d s o f some t y p i c a l a c i d a n d some l o s s o f a c c u r a c y w i l l e n s u e . A c c o r d i n g t o Duncombe ( 1 9 6 3 ) , f o r t h e m i c r o - d e t e r m i n a t i o n w h i c h was u s e d i n t h e p r e s e n t s t u d y , a p a l m i t i c a c i d s t a n d a r d c u r v e g i v e s an a c c e p t a b l e d e g r e e o f a c c u r a c y . NEFA l e v e l s i n p l a s m a s i g n i f i c a n t l y i n c r e a s e d w i t h p r o t e c t e d t a l l o w (P < . 0 1 ) . S e v e r a l o t h e r r e s e a r c h e r s f o u n d a s i m i l a r r e s p o n s e ( G o o d e n a n d L a s c e l l e s , 1973; B i t m a n e t a l . , 1973; G o e r i n g e t a l . , 1977; B i n e s e t a l . , 1978; Sharma e t a l . , 1978; S m i t h e t a l . , 1 9 7 8 ) . T h e p r e d i c t e d mean NEFA c o n c e n t r a t i o n f o r h e i f e r s was 250.3 j/mole/1 v e r s u s 305.9 ^ m o l e / 1 1 32 f o r > 2nd l a c t a t i o n c o w s . I t i s n o t c l e a r why t h e t r e a t m e n t by l a c t a t i o n c a t e g o r y i n t e r a c t i o n was s i g n i f i c a n t . W h e r e a s t h e h e i f e r s on t h e c o n t r o l a n d PROTEC R t r e a t m e n t s h a d l o w e r p l a s m a NEFA c o n c e n t r a t i o n s t h a n t h e ^ 2 n d l a c t a t i o n c o w s , t h e r e v e r s e r e l a t i o n s h i p was t r u e f o r t h e PROTEC S r a t i o n . j . Rumen V o l a t i l e F a t t y A c i d s V a l u e s f o r rumen V F A s were n o t s u b j e c t e d t o ANOVA b e c a u s e s a m p l e s w e r e t a k e n o n l y f r o m one cow on t h e c o n t r o l t r e a t m e n t a n d two cows on e a c h o f t h e PROTEC S a n d PROTEC R t r e a t m e n t s . D e c r e a s e s i n t h e p r o d u c t i o n o f a c e t a t e a n d a r e d u c e d a c e t a t e : p r o p i o n a t e r a t i o a r e s u p p o r t e d by o t h e r s t u d i e s ( S t o r r y e t a l . , 1 9 7 4 a; P a l m q u i s t a n d J e n k i n s , 1980; S e i n e r a n d S h u l t z , 1 9 8 0 ) . 2. P e r i o d I I a . I n t a k e s I n t a k e s / c o w / d a y o f d r y m a t t e r , e n e r g y a n d p r o t e i n w e r e h i g h e r i n p e r i o d I I t h a n i n p e r i o d I . I t i s e v i d e n t t h a t by 15 weeks p o s t - p a r t u m t h e cow's a p p e t i t e was n o t l i m i t i n g f o r m i l k p r o d u c t i o n . I t c a n be s e e n f r o m t h e 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 ( T a b l e 25) f o r i n t a k e v a r i a b l e s t h a t t h e same e f f e c t s , b r e e d a n d l a c t a t i o n c a t e g o r y , t h a t w e r e s i g n i f i c a n t i n p e r i o d I ( T a b l e 6) r e m a i n e d s o i n p e r i o d I I . T h e same d i s c u s s i o n p o i n t s a p p l y h e r e 133 a s w e l l . b . P r o d u c t i o n P a r a m e t e r s i . M i l k a n d M i l k E n e r g y Th e m i l k a n d m i l k e n e r g y y i e l d s s u m m a r i z e d i n T a b l e 26 i n d i c a t e 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 f o r t h e f i r s t o r t h o g o n a l c o n t r a s t ( p o s t - c o n t r o l v e r s u s t h e c o m b i n e d e f f e c t s o f t h e p o s t - P R O T E C S a n d t h e p o s t - P R O T E C R r a t i o n s ) f o r m i l k , FCM, SCM o r m i l k e n e r g y p r o d u c t i o n when t h e a n i m a l s a l l r e c e i v e d t h e same p o s t - t r e a t m e n t r a t i o n . A c t u a l l y , t h e a v e r a g e f o r t h e p r e d i c t e d mean m i l k y i e l d s f o r t h e p o s t - P R O T E C S (PS) a n d p o s t -PROTEC R (PR) t r e a t m e n t s ( 2 5 . 0 5 k g / c o w / d a y ) was 18.1 % h i g h e r t h a n t h e p r e d i c t e d mean m i l k p r o d u c t i o n on t h e p o s t - c o n t r o l (PC) t r e a t m e n t (21.21 k g / c o w / d a y ) , w h e r e a s t h e a v e r a g e p r e d i c t e d mean f o r m i l k y i e l d on r a t i o n s w i t h p r o t e c t e d t a l l o w i n p e r i o d I ( 2 7 . 9 3 k g / c o w / d a y ) was 21 % h i g h e r t h a n t h a t on t h e c o n t r o l ( 2 3 . 0 7 k g / c o w / d a y ) . F r o m t h i s c o m p a r i s o n i t i s e v i d e n t t h a t t h e r e was a c a r r y o v e r e f f e c t i n t o t h e p e r i o d i m m e d i a t e l y p o s t -t r e a t m e n t , due p e r h a p s t o a b e t t e r e n e r g y s t a t u s o f t h e cows f e d p r o t e c t e d t a l l o w when e n e r g y demands w e r e most c r i t i c a l i n e a r l y l a c t a t i o n , c a u s i n g them t o r e a c h a h i g h e r p e a k m i l k y i e l d t h a n cows n o t r e c e i v i n g p r o t e c t e d t a l l o w . T h e d e c l i n e s i n a v e r a g e p r e d i c t e d mean d a i l y m i l k y i e l d f r o m p e r i o d I t o I I on t h e c o n t r o l / P C , PROTEC S/PS a n d PROTEC R/PR t r e a t m e n t s w e r e : 8.1 %, 8.4 % a n d 12.3 %, r e s p e c t i v e l y . A l o n g e r t e r m t r i a l w o u l d h a v e t o be c o n d u c t e d t o d e t e r m i n e t h e e f f e c t on t o t a l l a c t a t i o n 134 p e r f o r m a n c e o f f e e d i n g p r o t e c t e d t a l l o w d u r i n g e a r l y l a c t a t i o n . T h e 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 ( T a b l e 28) f o r m i l k , FCM, SCM a n d m i l k e n e r g y show e s s e n t i a l l y t h e same s i g n i f i c a n t e f f e c t s i n t h e m o d e l i n p e r i o d I I a s f o r p e r i o d I o u t p u t s . T h e ( T x B x L ) i n t e r a c t i o n was s i g n i f i c a n t f o r m i l k y i e l d b u t n o t f o r FCM, SCM o r m i l k G.E. a s was t h e c a s e i n p e r i o d I I . T h e c o v a r i a b l e , d a y s i n p e r i o d , became s i g n i f i c a n t i n p e r i o d I I f o r m i l k y i e l d (P < . 0 5 ) . i i . M i l k C o m p o s i t i o n W h e r e a s t h e r e was a s i g n i f i c a n t e f f e c t o f p r o t e c t e d t a l l o w on m i l k p r o t e i n % a n d m i l k f a t y i e l d i n p e r i o d I , t h e s e d i f f e r e n c e s d i s a p p e a r e d i n p e r i o d I I ( T a b l e 2 7 ) . T h e r e w e r e no c a r r y o v e r e f f e c t s i n p e r i o d I I f o r m i l k c o m p o s i t i o n d u e t o f e e d i n g p r o t e c t e d t a l l o w i n e a r l y l a c t a t i o n . T h i s was t o be e x p e c t e d a t l e a s t f o r t h e m i l k f a t c o n t e n t b e c a u s e s t u d i e s on f e e d i n g p r o t e c t e d p o l y u n s a t u r a t e d l i p i d s t o l a c t a t i n g cows h a v e d e m o n s t r a t e d t h a t r e m o v a l o f t h e s u p p l e m e n t c a u s e s a r e t u r n o f t h e m i l k C18:2 l e v e l s t o n o r m a l w i t h i n 3 d a y s ( C o o k e t a l . , 1 9 7 2 ) . 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 ( T a b l e 28) f o r m i l k c o m p o s i t i o n v a r i a b l e s p a r a l l e l t h o s e f o r p e r i o d I . T h e ( T x B x L ) i n t e r a c t i o n was no l o n g e r s i g n i f i c a n t f o r p r o t e i n a n d l a c t o s e y i e l d s a n d t h e c o v a r i a b l e became s i g n i f i c a n t f o r b o t h v a r i a b l e s (P < . 0 5 ) . 135 c . E f f i c i e n c y R a t i o s A s w i t h m i l k y i e l d s t h e d i f f e r e n c e b e t w e e n g r o u p s r e c e i v i n g p r o t e c t e d t a l l o w a n d t h e c o n t r o l g r o u p , f o r t h e e f f i c i e n c y r a t i o s , c a r r i e d o v e r i n t o p e r i o d I I . T h e PS a n d PR g r o u p s w e r e more e f f i c i e n t m i l k a n d m i l k e n e r g y p r o d u c e r s (P < .01) t h a n was t h e PC g r o u p . I n a s t u d y c o n d u c t e d by S m i t h e t a l . ( 1 9 7 8 ) cows were s p l i t i n t o 3 g r o u p s a n d f o r 15 w e e k s , 2 g r o u p s r e c e i v e d p r o t e c t e d t a l l o w w h i l e t h e 3 r d g r o u p was f e d a c o n t r o l r a t i o n . E f f i c i e n c i e s o f m i l k p r o d u c t i o n were h i g h e r d u r i n g t h e t r e a t m e n t p e r i o d . F o r weeks 16-20 a l l cows were s w i t c h e d t o a common r a t i o n w i t h o u t p r o t e c t e d t a l l o w a n d t h e e f f i c i e n c i e s o f p r o d u c t i o n m e a s u r e d o n l y i n weeks 19 a n d 20 w e r e h i g h e r f o r t h e p o s t - p r o t e c t e d t a l l o w g r o u p s t h a n f o r t h e p o s t - c o n t r o l g r o u p , a l t h o u g h t h e d i f f e r e n c e was n o t s i g n i f i c a n t (P > . 0 5 ) . I t s h o u l d be n o t e d t h a t t h e e f f i c i e n c y r a t i o s i n p e r i o d I I ( T a b l e 29) show t h a t t h e e f f i c i e n c y o f p r o d u c t i o n o f m i l k a n d m i l k e n e r g y o u t p u t s p e r u n i t o f G.E. w e r e 83 % a n d 80 % o f t h e i r e f f i c i e n c i e s i n p e r i o d I f o r t h e PS a n d PR cows c o m b i n e d , a n d t h e PC c o w s , r e s p e c t i v e l y . T h e c o r r e s p o n d i n g v a l u e s f o r e f f i c i e n c y o f m i l k o u t p u t s p e r u n i t o f C P . w e r e 80 % a n d 78 %. T h e r e i s no a p p a r e n t r e a s o n why t h e H o l s t e i n s were more e f f i c i e n t i n p e r i o d I I t h a n t h e A y r s h i r e s f o r m i l k / G . E . a n d m i l k / C P . , p a r t i c u l a r l y i n l i g h t o f t h e f a c t t h a t t h i s r e l a t i o n s h i p d i d n o t e x i s t i n p e r i o d I . 1 36 D. Summary a n d C o n c l u s i o n s T h e o b j e c t i v e s o f t h i s s t u d y were t w o f o l d . T h e f i r s t o b j e c t i v e was t o c o m p a r e r a t i o n s w i t h o r w i t h o u t p r o t e c t e d t a l l o w a d d e d a t 8% o f t h e c o n c e n t r a t e , when f e d t o d a i r y cows d u r i n g t h e f i r s t 15 weeks o f l a c t a t i o n . T h e s e c o n d o b j e c t i v e was t o c o m p a r e the- two t y p e s o f p r o t e c t e d t a l l o w s (made e i t h e r w i t h s o y b e a n m e a l o r c a n o l a m e a l a s t h e p r o t e i n s o u r c e , i n c o m b i n a t i o n w i t h a p p r o x i m a t e l y 4 0 % t a l l o w ) . T h e r e s u l t s o f t h i s s t u d y i n d i c a t e t h a t p r o t e c t e d t a l l o w , when f e d u n d e r t h e c o n d i t i o n s s p e c i f i e d p r o d u c e d s i g n i f i c a n t i n c r e a s e s o v e r t h e c o n t r o l r a t i o n i n t h e y i e l d s a n d e f f i c i e n c y o f p r o d u c t i o n o f m i l k p e r u n i t i n t a k e o f e n e r g y a n d p r o t e i n . T h e a p p a r e n t d i g e s t i b i l i t y o f E . E . a n d t h e l e v e l o f b l o o d NEFA i n cows f e d p r o t e c t e d t a l l o w were h i g h e r t h a n i n t h o s e f e d t h e c o n t r o l r a t i o n . T h e r e was a s i g n i f i c a n t d e c r e a s e i n m i l k p r o t e i n % f o r r a t i o n s c o n t a i n i n g p r o t e c t e d t a l l o w . T h e m o l a r % o f a c e t a t e a n d t h e a c e t a t e i p r o p i o n a t e r a t i o w ere a l s o d e c r e a s e d w i t h p r o t e c t e d t a l l o w r a t i o n s . T h e p r o t e c t e d t a l l o w r a t i o n s h a d no s i g n i f i c a n t e f f e c t on t h e i n t a k e s o f d r y m a t t e r , e n e r g y o r p r o t e i n . I n a d d i t i o n , t h e r e were no s i g n i f i c a n t d i f f e r e n c e s i n t h e d i g e s t i b i l i t i e s o f D.M., G.E., N, ADF, a n d m i n e r a l s o r t h e y i e l d s o f SCM, m i l k G.E. a n d m i l k p r o t e i n . T h e r e w e r e no s i g n i f i c a n t d i f f e r e n c e s b e t w e e n t h e s o y b e a n m e a l - p r o t e c t e d t a l l o w a n d t h e c a n o l a m e a l - p r o t e c t e d t a l l o w f o r a n y p a r a m e t e r e x c e p t f o r t h e a p p a r e n t d i g e s t i b i l i t y o f e t h e r 137 e x t r a c t w h i c h was s i g n i f i c a n t l y h i g h e r on t h e c a n o l a m e a l -p r o t e c t e d t a l l o w r a t i o n ( P < . 0 5 ) . When p r o t e c t e d t a l l o w was r e m o v e d f r o m t h e r a t i o n s a t t h e e n d o f 15 weeks o f l a c t a t i o n a n d a 16 % c r u d e p r o t e i n d a i r y c o n c e n t r a t e was f e d d u r i n g w eeks 16-20 ( p e r i o d I I ) , cows f o r m e r l y f e d p r o t e c t e d t a l l o w r a t i o n s m a i n t a i n e d s i g n i f i c a n t l y h i g h e r e f f i c i e n c i e s o f m i l k p r o d u c t i o n t h a n t h e p o s t - c o n t r o l g r o u p ( P < . 0 1 ) . T h e r e were no s i g n i f i c a n t d i f f e r e n c e s i n t h e o t h e r p a r a m e t e r s s t u d i e d . I n p e r i o d I I t h e r e w e r e no s i g n i f i c a n t d i f f e r e n c e s b e t w e e n t h e PS a n d PR g r o u p s e x c e p t f o r t h e i n t a k e s o f d r y m a t t e r , e n e r g y a n d p r o t e i n f r o m c o n c e n t r a t e s , w h i c h w e r e a l l s i g n i f i c a n t l y l o w e r f o r t h e PR g r o u p t h a n t h e PS g r o u p ( P < . 0 5 ) . F r o m t h e r e s u l t s o f t h e p r e s e n t s t u d y i t c a n be recommended t h a t p r o t e c t e d t a l l o w c a n be f e d a t 8% o f t h e c o n c e n t r a t e , t o d a i r y cows i n e a r l y l a c t a t i o n i n o r d e r t o i n c r e a s e t h e p r o d u c t i o n o f m i l k a n d FCM w h i c h i s b r o u g h t a b o u t by an i m p r o v e m e n t i n t h e e f f i c i e n c y o f p r o d u c t i o n f r o m u n a l t e r e d f e e d , e n e r g y a n d p r o t e i n i n t a k e s . C a n o l a m e a l - p r o t e c t e d t a l l o w i s e q u a l l y a s e f f e c t i v e a s s o y b e a n m e a l - p f o t e c t e d t a l l o w i n p r o d u c i n g i n c r e a s e s i n p r o d u c t i v i t y a n d e f f i c i e n c i e s o f p r o d u c t i o n . T h i s i s v e r y n o t e w o r t h y b e c a u s e i t means t h a t p r o t e c t e d t a l l o w may be p r o d u c e d u s i n g t h e l e s s e x p e n s i v e c a n o l a m e a l i n s t e a d o f s o y b e a n m e a l a s t h e p r o t e i n s o u r c e . T h i s w o u l d r e p r e s e n t a s u b s t a n t i a l r e d u c t i o n i n t h e c o s t s o f p r o d u c t i o n . I n a d d i t i o n , a C a n a d i a n c o m m o d i t y may be u s e d i n s t e a d o f a p r o d u c t w h i c h , f o r W e s t e r n Canadian m a n u f a c t u r e r s , must be i m p o r t e d from the U.S. 139 I V . BIBLIOGRAPHY A l l i s o n , M . J . 1970. " N i t r o g e n M e t a b o l i s m o f Rumen M i c r o o r g a n i s m s , " i n P h y s i o l o g y o f D i g e s t i o n a n d M e t a b o l i s m  i n t h e R u m i n a n t . A . T . P h i l l i p s o n ( e d . ) , p p . 4 5 6 - 4 7 3 . A l l i s o n , M .J., M.P. B r y a n t , I . K a t z a n d M. R e e n e y . 1962. M e t a b o l i c F u n c t i o n o f B r a n c h e d - C h a i n V o l a t i l e F a t t y A c i d s , G r o w t h F a c t o r s f o r R u m i n o c o c c i . I I . B i o s y n t h e s i s o f H i g h e r B r a n c h e d - C h a i n F a t t y A c i d s a n d A l d e h y d e s . J . B a c t . 8 3 : 1 0 8 4 - 1 0 9 3 . A m e r i c a n H e a r t A s s o c i a t i o n . 1973. D i e t a n d C o r o n a r y H e a r t D i s e a s e . New Y o r k : A m e r i c a n H e a r t A s s o c i a t i o n . A n n i s o n , E . F . 1972. "Rumen M e t a b o l i s m a n d P r o t e c t e d N u t r i e n t s , " i n U. o f N o t t i n g h a m N u t r . C o n f . f o r F e e d M a n u f a c t u r e r s : 6. H. Swan a n d D. L e w i s ( e d s . ) . E d i n b u r g h : C h u r c h i l l L i v i n g s t o n e , p p . 2-21. A n n i s o n , E . F . a n d D. L e w i s . 1959. M e t a b o l i s m i n t h e Rumen. L o n d o n : M e t h u e n & C o . L t d . A n n i s o n , E . F . , F . L . L i n z e l l , S. F a z a k e r l e y a n d B.W. N i c h o l s . 1967. T h e O x i d a t i o n a n d U t i l i z a t i o n o f P a l m i t a t e , S t e a r a t e , O l e a t e a n d A c e t a t e by t h e Mammary G l a n d o f t h e F e d G o a t i n R e l a t i o n t o t h e i r O v e r a l l M e t a b o l i s m , a n d t h e R o l e o f P l a s m a P h o s p h o l i p i d s a n d N e u t r a l L i p i d s i n M i l k F a t S y n t h e s i s . B i o c h e m . J . 102: 6 3 7 - 6 4 7 . A r m s t r o n g , D.G. 1968. " P r i n c i p l e s o f F a t U t i l i z a t i o n , " i n P r o c . o f t h e 2 n d N u t r . C o n f . f o r F e e d M a n u f a c t u r e r s . H~! Swan & D. L e w i s ( e d s ) . L o n d o n : J . & A. C h u r c h i l l , p p . 2-21 . A r m s t r o n g , D.E. a n d D.E. B e e v e r . 1969. P o s t - A b o m a s a l D i g e s t i o n o f C a r b o h y d r a t e s i n t h e A d u l t R u m i n a n t . P r o c . N u t r . S o c . 28: 1 2 1 - 1 3 1 . A u s t r a l i a n Academy o f S c i e n c e . 1975. R e p o r t o f a W o r k i n g G r o u p on D i e t a n d C o r o n a r y H e a r t D i s e a s e , R e p o r t 18. B a i l e y , R.W. 1962. c - G a l a c t o s i d a s e A c t i v i t y o f Rumen B a c t e r i a . N a t u r e 195: 7 9 - 8 0 . B a n k s , W., J . L . C l a p p e r t o n , M o r a g E . F e r r i e a n d A g n e s G. W i l s o n . 1976. E f f e c t o f F e e d i n g F a t t o D a i r y Cows R e c e i v i n g a F a t - D e f i c i e n t B a s a l D i e t . I . M i l k Y i e l d a n d 1 40 C o m p o s i t i o n . J . D a i r y R e s . 43: 2 1 3 - 2 1 8 . B a r r y , J.M., W. B a r t l e y , J . L . L i n z e l l a n d D.S. R o b i n s o n . 1963. Th e U p t a k e f r o m t h e B l o o d o f T r i g l y c e r i d e F a t t y A c i d s o f C h y l o m i c r a a n d L o w - D e n s i t y L i p o p r o t e i n s by t h e Mammary G l a n d o f t h e G o a t . B i o c h e m . J . 8 9 : 6-11. B a r t l e y , J . C , S. A b r a h a m a n d I . L . C h a i k o f f . 1967. F a c t o r s I n f l u e n c i n g t h e P a t t e r n o f F a t t y A c i d s S y n t h e s i z e d b y C e l l -F r e e P r e p a r a t i o n s o f L a c t a t i n g R a t Mammary G l a n d . B i o c h i m . B i o p h y s . A c t a 144: 5 1 - 6 0 . Bauman, D.E., R.E. Brown a n d C . L . D a v i s . 1970. P a t h w a y s o f F a t t y A c i d S y n t h e s i s a n d R e d u c i n g E q u i v a l e n t G e n e r a t i o n i n Mammary G l a n d o f R a t , Sow a n d Cow. A r c h i v e s o f B i o c h e m i s t r y a n d B i o p h y s i c s 140: 2 3 7 - 2 4 4 . Bauman, D.E., R.W. M e l l e n b e r g e r a n d R.G. D e r r i g . 1973. F a t t y A c i d S y n t h e s i s i n S h e e p Mammary T i s s u e . J . D a i r y S c i . 56: 1 3 1 2 - 1 3 1 8 . Bauman, D.E. a n d C . L . D a v i s . 1974. B i o s y n t h e s i s o f M i l k F a t , i n L a c t a t i o n : A C o m p r e h e n s i v e T r e a t i s e , V o l . 2. B.L. " L a r s o n a n d V.R. S m i t h ( e d s ) . New Y o r k : A c a d e m i c P r e s s , p p . 3-30. Bauman, D.E., R.W. M e l l e n b e r g e r a n d D.L. I n g l e . 1974. M e t a b o l i c A d a p t a t i o n s i n F a t t y A c i d a n d L a c t o s e B i o s y n t h e s i s by S h e e p Mammary T i s s u e D u r i n g C e s s a t i o n o f L a c t a t i o n . J . D a i r y S c i . 57: 7 1 9 - 7 2 3 . Bauman, D.E. a n d C . L . D a v i s . 1975. " R e g u l a t i o n o f L i p i d M e t a b o l i s m , " i n D i g e s t i o n a n d M e t a b o l i s m i n t h e R u m i n a n t . P r o c . o f t h e I V . I n t . Symp. on R u m i n a n t P h y s i o l o g y . I.W. M c D o n a l d a n d A . C . I . W a r n e r ( e d s . ) . S y d n e y : T h e U. o f New E n g l a n d P u b l . U n i t , p p . 4 9 6 - 5 0 9 . B a u m g a r d t , B.R. 1970. " R e g u l a t i o n o f F e e d I n t a k e a n d E n e r g y B a l a n c e , " i n P h y s i o l o g y o f D i g e s t i o n a n d M e t a b o l i s m i n t h e R u m i n a n t . A.T\ P h i l l i p s o n ( e d . ) . N e w c a s t l e Upon T y n e : O r i e l P r e s s , p p . 2 3 5 - 2 5 3 . B i n e s , J . A . , P.E. Brumby, J . E . S t o r r y , R o s e m a r y . J . F u l f o r d a n d G.D. B r a i t h w a i t e . 1978. J . A g r i c . S c i . , Camb. 9 1 : 135-150. B i t m a n , J . , L . P . D r y d e n , H.K. G o e r i n g , T.R. Wrenn, R.A. Y o n c o s k i e a n d L . F . E d m o n d s o n . 1973. E f f i c i e n c y o f T r a n s f e r o f P o l y u n s a t u r a t e d F a t s i n t o M i l k . J . Amer. O i l Chem. S o c . 50: 9 3 - 9 8 . B l a x t e r , K . L . 1971. M e t h o d s o f M e a s u r i n g t h e E n e r g y M e t a b o l i s m o f A n i m a l s a n d I n t e r p r e t a t i o n o f R e s u l t s O b t a i n e d . F e d . P r o c . F e d . Amer. S o c . E x p . B i o l . 3 0 : 1 4 3 6 - 1 4 4 3 . 141 B l a x t e r , K . L . a n d R.F. W i l s o n . 1962. T h e V o l u n t a r y I n t a k e o f R o u g h a g e s by S t e e r s . A n i m . P r o d . 4: 3 5 1 - 3 5 8 . B o d a , K., J . V a r a d y a n d I . H a v a s s y . 1976. " U t i l i z a t i o n o f U r e a - N i t r o g e n - 1 5 i n R u m i n a n t s , " i n T r a c e r S t u d i e s on Non- P r o t e i n N i t r o g e n f o r R u m i n a n t s . I I I . V i e n n a : I n t e r n a t n l . A t o m i c E n e r g y A g e n c y , p p . 1-12. B r o d e r i c k , G.A., T. K o w a l c z y k a n d L.D. S a l t e r . 1970. M i l k P r o d u c t i o n R e s p o n s e t o S u p p l e m e n t a t i o n w i t h E n c a p s u l a t e d M e t h i o n i n e P e r Os o r C a s e i n P e r Abomasum. J . D a i r y S c i . 53: 1 7 1 4 - 1 7 2 1 . Broome, A.W. 1968. "The U s e o f N o n - P r o t e i n N i t r o g e n i n A n i m a l F e e d s , " i n P r o c . o f t h e 2nd N u t r . C o n f . f o r F e e d  M a n u f a c t u r e r s . FU Swan a n d D. L e w i s ( e d s . ) . L o n d o n : J . & A. C h u r c h i l l L t d . , p p . 9 2 - 1 1 3 . B r o s t e r , W.H. 1969. " R e c e n t R e s e a r c h I n t o L e v e l s o f F e e d i n g f o r D a i r y Cows," i n P r o c . 3 r d N u t r . C o n f . f o r F e e d  M a n u f a c t u r e r s . H. Swan a n d D. L e w i s ( e d s . ) . L o n d o n : J . & A. C h u r c h i l l L t d . , p p . 5 3 - 7 9 . Brumby, P.E., J . E . S t o r r y a n d J.D. S u t t o n . 1972. M e t a b o l i s m o f C o d - L i v e r O i l i n R e l a t i o n t o M i l k F a t S e c r e t i o n . J . D a i r y R e s . 39: 167-182. Brumby, P.E., J . E . S t o r r y , J . A . B i n e s a n d R o s e m a r y J . F u l f o r d . 1978. J . A g r i c . S c i . , Camb. 9 1 : 151-159. B r y a n t , M.P. a n d J.M. R o b i n s o n . 1962. Some N u t r i t i o n a l C h a r a c t e r i s t i c s o f P r e d o m i n a n t C u l t u r a b l e R u m i n a l B a c t e r i a . J . B a c t e r i o l . 84: 6 0 5 - 6 1 4 . B r y a n t , M.P. a n d I.M. R o b i n s o n . 1963. A p p a r e n t I n c o r p o r a t i o n o f Ammonia a n d Amino A c i d C a r b o n D u r i n g G r o w t h o f S e l e c t e d S p e c i e s o f R u m i n a l B a c t e r i a . J . D a i r y S c i . 46: 150-154. B u r r o u g h s , W., D.K. N e l s o n a n d D.R. M a r t e n s . 1975. P r o t e i n P h y s i o l o g y a n d i t s A p p l i c a t i o n i n t h e L a c t a t i n g Cow: t h e M e t a b o l i z a b l e P r o t e i n F e e d i n g S t a n d a r d . J . A n i m . S c i . 4 1 : 9 3 3 - 9 4 4 . C h a l u p a , W. 1975. Rumen B y p a s s a n d P r o t e c t i o n o f P r o t e i n s a n d A m i n o A c i d s . J . D a i r y S c i . 58: 1 1 9 8 - 1 2 1 8 . C h a n d l e r , N . J . , l . B . R o b i n s o n , I . e . R i p p e r a n d P. F o w l e r . 1973. T h e E f f e c t o f F e e d i n g F o r m a l d e h y d e T r e a t e d S u n f l o w e r S e e d S u p p l e m e n t on t h e Y i e l d a n d C o m p o s i t i o n o f M i l k f a t . A u s t . J . D a i r y T e c h n o l . 28: 1 7 9 - 1 7 9 . C h r i s t e n s e n , D.A., G. S t e a c y a n d M a r l e n e C o c h r a n . 1978. P r o t e c t e d L i p i d s f o r L a c t a t i n g D a i r y Cows. C a n . J . A n i m . S c i . 58: 809 ( A b s t r . ) . 142 C h u r c h , D.C. 1970. D i g e s t i v e P h y s i o l o g y a n d N u t r i t i o n o f R u m i n a n t s , V o l . 1. C o r v a l l i s , O r e g o n : O.S.U. Book S t o r e s I n c . C l a r k , J . H . 1975. L a c t a t i o n a l R e s p o n s e s t o P o s t r u m i n a l A d m i n i s t r a t i o n o f P r o t e i n s a n d Am i n o A c i d s . J . D a i r y S c i . 58: 1 1 7 8 - 1 1 9 7 . C o o k , L . J . , T.W. S c o t t , K.A. F e r g u s o n a n d I.W. M c D o n a l d . 1970. P r o d u c t i o n o f P o l y u n s a t u r a t e d R u m i n a n t Body F a t s . N a t u r e , 338: 178-174. C o o k , L . J . , T.W. S c o t t a n d Y.S. P a n . 1972. F o r m a l d e h y d e -T r e a t e d C a s e i n - S a f f l o w e r O i l S u p p l e m e n t f o r D a i r y Cows. I I . E f f e c t on t h e F a t t y A c i d C o m p o s i t i o n o f P l a s m a a n d M i l k L i p i d s . J . D a i r y R e s . 39: 2 1 1 - 2 1 8 . Commonwealth S c i e n t i f i c & I n d u s t r i a l R e s e a r c h O r g a n i z a t i o n . 1974. I m p r o v e m e n t s i n a n d R e l a t i n g t o F e e d S u p p l e m e n t s f o r R u m i n a n t s . F S T A , V o l . 6, No. 3, p . 3P416. B r i t i s h P a t e n t 1 337 749 ( 1 9 7 3 ) . C u i t u n , L . L . , W.H. H a l e , B. T h e u r e r , F.D. D r y d e n a n d J . A . M a r c h e l l o . 1975. P r o t e i n P r o t e c t e d F a t f o r R u m i n a n t s . I . D i g e s t i o n a n d P e r f o r m a n c e i n F a t t e n i n g S t e e r s ; J . A n i m . S c i . 4 0 : 6 9 1 - 6 9 6 . Dawson, R.M.C. 1959. H y d r o l y s i s o f L e c i t h i n a n d L y s o l e c i t h i n by Rumen M i c r o o r g a n i s m s o f t h e S h e e p . N a t u r e 183: 1822-1823. Dawson, R.M.C. a n d P. Kemp. 1970. " B i o h y d r o g e n a t i o n o f D i e t a r y F a t s i n R u m i n a n t s , " i n P h y s i o l o g y o f D i g e s t i o n a n d  M e t a b o l i s m i n t h e R u m i n a n t . A . T . P h i l l i p s o n ( e d . ) . New C a s t l e u p o n T y n e : O r i e l P r e s s L i m i t e d , p p . 5 0 4 - 5 1 8 . D i n i u s , D.A., R.R. O l t j e n , C K . L y o n , G.O. K o h l e r a n d H.G. W a l k e r , J r . 1974. U t i l i z a t i o n o f a F o r m a l d e h y d e T r e a t e d C a s e i n - S a f f l o w e r O i l C o m p l e x by G r o w i n g a n d F i n i s h i n g S t e e r s . J . A n i m . S c i . 39: 1 2 4 - 1 3 3 . D i n i u s , D.A., L . F . Ed m o n d s o n , W. K i m o t o a n d R.R. O l t j e n . 1 975. G r o w t h , B l o o d P a r a m e t e r s a n d T i s s u e L i p i d s o f F i n i s h i n g C a t t l e F e d a F o r m a l d e h y d e T r e a t e d C a s e i n - S a f f l o w e r O i l C o m p l e x . J . A n i m . S c i . 40: 3 5 8 - 3 6 5 . D r y d e n , F.D., J . A . M a r c h e l l o , L . L . C u i t u n a n d W.H. H a l e . 1975. P r o t e i n P r o t e c t e d F a t f o r R u m i n a n t s . I I . S e r u m L i p i d s a n d L i p o p r o t e i n s . J . A n i m . S c i . 40: 6 9 7 - 7 0 5 . Duncombe, W.G. 1963. T h e C o l o r i m e t r i c M i c r o - D e t e r m i n a t i o n o f L o n g - C h a i n F a t t y A c i d s . B i o c h e m . J . 88: 7-10. Duncombe, W.G. 1964. T h e C o l o r i m e t r i c M i c r o - D e t e r m i n a t i o n o f 143 N o n - E s t e r i f i e d F a t t y A c i d s i n P l a s m a . C l i n . C h i m . A c t a , 9: 122-125. D u n k l e y , W.L., N.E. S m i t h a n d A.A. F r a n k e . 1977. E f f e c t s o f F e e d i n g P r o t e c t e d T a l l o w on C o m p o s i t i o n o f M i l k a n d M i l k F a t . J . D a i r y S c i . 60: 1 8 6 3 - 1 8 6 9 . E a s t e r , D . J . a n d R. D i l s . 1968. F a t t y A c i d B i o s y n t h e s i s . I V . P r o p e r t i e s o f A c e t y l - C o A C a r b o x y l a s e i n L a c t a t i n g - R a b b i t Mammary G l a n d . B i o c h i m . B i o p h y s . A c t a 152: 6 5 3 - 6 6 8 . E d m o n d s o n , L . F . , R.A. Y o n c o s k i e , N.H. R a i n e y , F.W. D o u g l a s a n d J . B i t m a n . 1974. F e e d i n g E n c a p s u l a t e d O i l s t o I n c r e a s e t h e P o l y u n s a t u r a t i o n i n M i l k a n d M e a t F a t . J . Amer. O i l Chem. S o c . 5 1 : 7 2 - 7 6 . E l - S h a z l y , K. 1952. D e g r a d a t i o n o f P r o t e i n i n t h e Rumen o f t h e S h e e p . I . Some V o l a t i l e F a t t y A c i d s , i n c l u d i n g B r a n c h e d -C h a i n I s o m e r s , f o u n d i_n v i v o . B i o c h e m . J . 5 1 : 6 4 0 - 6 4 7 . E m e r y , R.S. 1973. B i o s y n t h e s i s o f M i l k F a t . J . D a i r y S c i . 56: 1 1 8 7 - 1 1 9 5 . F a i c h n e y , G . J . , H. L l o y d D a v i e s , T.W. S c o t t a n d L . J . C o o k . 1972. T h e I n c o r p o r a t i o n o f L i n o l e i c A c i d i n t o t h e T i s s u e s o f G r o w i n g S t e e r s o f f e r e d a D i e t a r y S u p p l e m e n t o f F o r m a l d e h y d e - T r e a t e d C a s e i n - S a f f l o w e r O i l . A u s t . J . B i o l . S c i . 2 5 : 2 0 5 - 2 1 2 . F a i c h n e y , G . J . , T.W. S c o t t a n d L . J . C o o k . 1973. T h e U t i l i z a t i o n by G r o w i n g Lambs o f a C a s e i n - S a f f l o w e r O i l S u p p l e m e n t T r e a t e d w i t h F o r m a l d e h y d e . A u s t . J . B i o l . S c i . 2 6: 117 9 - 1 1 8 8 . F e d e r a t i o n o f A m e r i c a n S o c i e t i e s f o r E x p e r i m e n t a l B i o l o g y . 1968. M e t a b o l i s m . P.L. A l t m a n a n d D.S. D i t t m e r ( e d s . ) . M a r y l a n d : F e d . Amer. S o c . E x p . B i o l . F e r g u s o n , K.A. 1975. "The P r o t e c t i o n o f D i e t a r y P r o t e i n s a n d Amino A c i d s a g a i n s t M i c r o b i a l F e r m e n t a t i o n i n t h e Rumen," i n D i g e s t i o n a n d M e t a b o l i s m i n t h e R u m i n a n t . P r o c . o f t h e I V . I n t e r n a t . Symp. on R u m i n a n t P h y s i o l o g y . A r m i d a l e : U. o f New E n g l a n d P u b l . U n i t , p p . 4 4 8 - 4 6 4 . F e r g u s o n , K.A., J . A . H e m s l e y a n d P . J . R e i s . 1967. N u t r i t i o n a n d W ool G r o w t h . T h e E f f e c t o f P r o t e c t i n g D i e t a r y P r o t e i n f r o m M i c r o b i a l D e g r a d a t i o n i n t h e Rumen. A u s t . J . S c i . 30: 2 1 5 - 2 1 7 . F i s h e r , L . J . 1969. E f f e c t o f M e t h i o n i n e I n f u s i o n on M i l k P r o d u c t i o n a n d P l a s m a - F r e e A m i n o A c i d s o f L a c t a t i n g Cows. J . D a i r y S c i . 52: 943 ( A b s t r . ) . F i s h e r , L . J . 1972. R e s p o n s e o f L a c t a t i n g Cows t o t h e 144 I n t r a v e n o u s I n f u s i o n o f Amino A c i d s . C a n . J . A n i m . S c i . 52: 3 7 7 - 3 8 4 . F i s h e r , L . J . 1979. S u p p l e m e n t a t i o n w i t h P r o t e c t e d L i p i d a s a Means o f A l l e v i a t i n g " S p r i n g P a s t u r e " I n d u c e d M i l k F a t D e p r e s s i o n . C a n . J . A n i m . S c i . 59: 7 0 7 - 7 1 2 . F o g e r t y , A . C . a n d A.R. J o h n s o n . 1980. " I n f l u e n c e o f N u t r i t i o n a l F a c t o r s on t h e Y i e l d a n d C o n t e n t o f M i l k F a t : P r o t e c t e d P o l y u n s a t u r a t e d F a t i n t h e D i e t , " i n F a c t o r s  A f f e c t i n g t h e Y i e l d s a n d C o n t e n t s o f M i l k C o n s t i t u e n t s o f  C o m m e r c i a l I m p o r t a n c e . I n t e r n a t l . D a i r y F e d . D o c ument 125, p p . 9 6 - 1 0 4 . F r a e n k e l - C o n r a t , H e i n z a n d H a r o l d . S. O l c o t t . 1948. T h e R e a c t i o n o f F o r m a l d e h y d e w i t h P r o t e i n s . V. C r o s s - L i n k i n g b e t w e e n Amino a n d P r i m a r y A m i de o r G u a n i d y l G r o u p s . J . Amer. O i l Chem. S o c . 7 0 : 2 6 7 3 - 2 6 8 4 . G a c u l a , M.C. J r . , S.N. G a u n t a n d R.A. Demon J r . 1965. E s t i m a t e o f Age E f f e c t on M i l k C o m p o s i t i o n . J . A g r i c . R e s . 35: 2 3 7 - 2 4 9 . G a i n e s , W.L. 1928. T h e E n e r g y B a s i s o f M e a s u r i n g M i l k Y i e l d i n D a i r y Cows. I l l i n o i s A g r . E x p t . S t a . , B u l l . P. 308. G a r r e t t , W.N., Y.T. Y a n g , W.L. D u n k l e y a n d L.M. S m i t h . 1 976a. I n c r e a s i n g t h e P o l y u n s a t u r a t e d F a t C o n t e n t o f B e e f a n d Lamb. J . A n i m . S c i . 42: 8 4 5 - 8 5 3 . G a r r e t t , W.N., Y.T. Y a n g , W.L. D u n k l e y a n d L.M. S m i t h . 1976b. E n e r g y U t i l i z a t i o n , F e e d l o t P e r f o r m a n c e a n d F a t t y A c i d C o m p o s i t i o n o f B e e f S t e e r s F e d P r o t e i n E n c a p s u l a t e d T a l l o w o r V e g e t a b l e O i l s . J . A n i m . S c i . 42: 1 5 2 2 - 1 5 3 3 . G a r t o n , G.A. 1961. " I n f l u e n c e o f t h e Rumen on t h e D i g e s t i o n a n d M e t a b o l i s m o f L i p i d s , " i n D i g e s t i v e P h y s i o l o g y a n d  N u t r i t i o n o f t h e R u m i n a n t . D. L e w i s ( e d . ) . L o n d o n : B u t t e r w o r t h s , p p . 1 4 0 - 1 5 1 . G a r t o n , G.A. 1964. " A s p e c t s o f L i p i d M e t a b o l i s m i n R u m i n a n t s , " i n M e t a b o l i s m a n d P h y s i o l o g i c a l S i g n i f i c a n c e o f L i p i d s . R.M.C. Dawson a n d D.N. R h o d e s ( e d s . ) . L o n d o n : J o h n W i l e y & S o n s L t d . , p p . 3 3 5 - 3 4 8 . G a r t o n , G.A. 1965. "The D i g e s t i o n a n d A s s i m i l a t i o n o f L i p i d s , " i n P h y s i o l o g y o f D i g e s t i o n i n t h e R u m i n a n t . R.W. D o u g h e r t y ( e d . ) . W a s h i n g t o n : B u t t e r w o r t h s , p p . 3 9 0 - 3 9 8 . G a r t o n , G.A. 1967. "The D i g e s t i o n a n d A b s o r p t i o n o f L i p i d s i n R u m i n a n t A n i m a l s , " i n W o r l d R e v i e w o f N u t r i t i o n a n d  D i e t e t i c s , No. 7. L o n d o n : P i t m a n M e d i c a l P u b l i s h i n g C o . L t d . , p p , 2 2 5 - 2 5 0 . 145 G a r t o n , G.A., A.K. L o u g h a n d E . V i o q u e . 1959. T h e E f f e c t o f S h e e p Rumen C o n t e n t s on T r i g l y c e r i d e s in v i t r o . B i o c h e m . J . 7 3 : 4 6 P - 4 7 P . G a r t o n , G.A., P.N. H o b s o n a n d A.K. L o u g h . 1958. L i p o l y s i s i n t h e Rumen. N a t u r e 182: 1 5 1 1 - 1 5 1 2 . G a u n t , S.N. 1973. G e n e t i c a n d E n v i r o n m e n t a l C h a n g e s P o s s i b l e i n M i l k C o m p o s i t i o n . J . D a i r y S c i . 56: 2 7 0 - 2 7 8 . G o e r i n g , H.K., C . J . G o r d o n , T.R. Wrenn, J . B i t m a n , R.L. K i n g a n d F.W. D o u g l a s , J r . 1976. E f f e c t o f F e e d i n g P r o t e c t e d S a f f l o w e r O i l on Y i e l d , C o m p o s i t i o n , F l a v o r , a n d O x i d a t i v e S t a b i l i t y o f M i l k . J . D a i r y S c i . 59: 4 1 6 - 4 2 5 . G o e r i n g , H.K., T.R. Wrenn, L . F . E d m o n d s o n , J.R. W e y a n t , D.L. Wood a n d J . B i t m a n . 1977. F e e d i n g P o l y u n s a t u r a t e d V e g e t a b l e O i l s t o L a c t a t i n g Cows. J . D a i r y S c i . 60: 7 3 9 -7 4 7 . G o o d e n , J.M. a n d A.K. L a s c e l l e s . 1973. E f f e c t o f F e e d i n g P r o t e c t e d L i p i d on t h e U p t a k e o f P r e c u r s o r s o f M i l k F a t by t h e B o v i n e Mammary G l a n d . A u s t . J . B i o l . S c i . 26: 1201-1210. G r a i n g e r , R.B., M.C. B e l l , J.W. S t r o u d a n d F.H. B a k e r . 1961. E f f e c t o f V a r i o u s C a t i o n s a n d C o r n O i l on C r u d e C e l l u l o s e D i g e s t i b i l i t y by S h e e p . J . A n i m . S c i . 20: 3 1 9 - 3 2 2 . H a a s e , G. 1977. P r e s e n t S t a t u s i n R e s e a r c h , D e v e l o p m e n t a n d C o m m e r c i a l i z a t i o n o f P o l y u n s a t u r a t e d M e a t a n d D a i r y P r o d u c t s . I I . P r o d u c t i o n o f P o l y - F o o d s . M i l c h w i s s e n s c h a f t 32: 3 3 3 - 3 3 6 . H a g e m e i s t e r , H., W. K a u f m a n n a n d E . P f e f f e r . 1976. " F a c t o r s I n f l u e n c i n g t h e S u p p l y o f N i t r o g e n a n d Amino A c i d s t o t h e I n t e s t i n e o f D a i r y Cows," i n P r o t e i n M e t a b o l i s m a n d  N u t r i t i o n . D . J .A. C o l e ( e d . ) . L o n d o n : B u t t e r w o r t h s , p p . 4 2 5 - 4 3 9 . H a r d w i c k , D.C. 1966. T h e F a t e o f A c e t y l G r o u p s D e r i v e d f r o m G l u c o s e i n t h e I s o l a t e d P e r f u s e d G o a t U d d e r . B i o c h e m i c a l J . 99: 2 2 8 - 2 3 1 . H a r f o o t , C G . 1978. A n a t o m y , P h y s i o l o g y a n d M i c r o b i o l o g y o f t h e R u m i n a n t D i g e s t i v e T r a c t . P r o g . i n L i p i d R e s . 17: 1-19. H a r r a p , B.S. 1973. R e c e n t D e v e l o p m e n t s i n t h e P r o d u c t i o n o f D a i r y P r o d u c t s w i t h I n c r e a s e d L e v e l s o f P o l y u n s a t u r a t i o n . A u s t . J . D a i r y T e c h n o l . p p . 101-104. H e m s l e y , J . A . , P . J . R e i s a n d A.M. Downes. 1973. I n f l u e n c e o f V a r i o u s F o r m a l d e h y d e T r e a t m e n t s on t h e N u t r i t i o n a l V a l u e o f 146 C a s e i n f o r W o o l G r o w t h . A u s t . J . B i o l . S c i . 2 6 : 9 6 1 -972. H i l d i t c h , T .P. a n d P.N. W i l l i a m s . 1964. T h e C h e m i c a l C o n s t i t u t i o n o f N a t u r a l F a t s . L o n d o n : S p o t t i s w o o d e , B a l l a n t y n e & C o . L t d . H o b s o n , P.N. 1971. "Rumen M i c r o o r g a n i s m s , " i n P r o g r e s s i n  I n d u s t r i a l M i c r o b i o l o g y , V o l . 9, p p . 4 1 - 7 7 . H o b s o n , P.N. a n d S.O. Mann. 1961. T h e I s o l a t i o n o f G l y c e r o l -F e r m e n t i n g a n d L i p o l y t i c B a c t e r i a f r o m t h e Rumen o f t h e S h e e p . J . G e n . M i c r o b i o l . 25: 2 2 7 - 2 4 0 . H o g a n , J . P . , P . J . C o n n e l l a n d S.C. M i l l s . 1972. T h e D i g e s t i o n o f S a f f l o w e r O i l - C a s e i n P a r t i c l e s P r o t e c t e d A g a i n s t R u m i n a l H y d r o g e n a t i o n i n S h e e p . A u s t . J . a g r i c . R e s . 2 3 : 8 7 - 9 5 . H o g a n , J . P . a n d R.M. H o g a n . 1976. T h e E v a l u a t i o n o f F o r m a l d e h y d e - T r e a t e d S u n f l o w e r - S e e d C a s e i n S u p p l e m e n t a s a S o u r c e o f L i n o l e i c A c i d f o r R u m i n a n t L i p i d s . A u s t . J . a g r i c . R e s . 2 7 : 129-138. H o o d , R.L. 1977. I_n v i v o M e a s u r e m e n t o f R e s i s t a n c e o f F o r m a l d e h y d e - T r e a t e d O i l s e e d S u p p l e m e n t s t o H y d r o g e n a t i o n i n t h e Rumen. J . D a i r y S c i . 60: 1 7 0 1 - 1 7 0 5 . H u h t a n e n , C.N., a n d L . S . G a l l . 1955. M a n o m e t r i c E s t i m a t i o n o f Rumen U r e a s e . J . B a c t e r i o l . 69: 1 0 2 - 1 0 3 . H u n g a t e , R.E. 1966. T h e Rumen a n d i t s M i c r o b e s . New Y o r k : A c a d e m i c P r e s s . J o h n s , A . T . 1955. E f f e c t o f t h e Rumen on D i e t a r y F a t . N a t u r e 175: 1 1 2 9 - 1 1 3 0 . J o h n s o n , A.R. a n d M.V. T r a c e y . 1975. A l t e r i n g F a t t y A c i d C o m p o s i t i o n o f R u m i n a n t P r o d u c t s . C e r e a l F o o d s W o r l d 20: 77-80 & 9 9 - 1 0 0 . J o h n s o n , D.G. a n d D.E. O t t e r b y . 1981. I n f l u e n c e o f D r y P e r i o d D i e t on E a r l y P o s t p a r t u m H e a l t h , F e e d I n t a k e , M i l k P r o d u c t i o n , a n d R e p r o d u c t i v e E f f i c i e n c y o f H o l s t e i n Cows. J . D a i r y S c i . 64: 2 9 0 - 2 9 5 . K a u f m a n n , W. 1980. " P r o t e i n D e g r a d a t i o n a n d S y n t h e s i s w i t h i n t h e R e t i c u l o - R u m e n i n R e l a t i o n t o M i l k P r o t e i n S y n t h e s i s , " i n F a c t o r s A f f e c t i n g t h e Y i e l d s a n d C o n t e n t s o f M i l k  C o n s t i t u e n t s o f C o m m e r c i a l I m p o r t a n c e . I n t e r n a t l . D a i r y F e d . D o c ument 125, p p . 152 - 1 5 8 . K a y , R.N.B. a n d P.N. H o b s o n . 1963. R e v i e w s o f t h e P r o g r e s s o f D a i r y S c i e n c e . S e c t i o n A. P h y s i o l o g y . J . D a i r y R e s . 30: 2 6 1 - 3 1 3 . 147 K e e n e y , M. 1970. " L i p i d M e t a b o l i s m i n t h e Rumen," i n P h y s i o l o g y o f D i g e s t i o n a n d M e t a b o l i s m i n t h e R u m i n a n t . A . T . P h i l l i p s o n ( e d . ) . p p . 4 8 9 - 5 0 3 . K e p l e r , C.R., K.P. H i r o n s , J . J . M c N e i l l a n d S.B. T o v e . 1966. I n t e r m e d i a t e s a n d P r o d u c t s o f B i o h y d r o g e n a t i o n o f L i n o l e i c A c i d by B u t y r i v i b r i o f i b r i s o l v e n s . J . b i o l . Chem. 241 : 1 3 5 0 - 1 3 5 4 . K o w a l c z y k , J . , E.R. O r s k o v , J . J . R o b i n s o n , a n d C S . S t e w a r t . 1977. E f f e c t o f F a t S u p p l e m e n t a t i o n on V o l u n t a r y F o o d I n t a k e a n d Rumen M e t a b o l i s m i n S h e e p . B r . J . N u t r . 37: 2 5 1 - 2 5 7 . K r o n f e l d , D.S., S. D o n o g h u e , J.M. N a y l o r , K. J o h n s o n a n d C A . B r a d l e y . 1980. M e t a b o l i c E f f e c t s o f F e e d i n g P r o t e c t e d T a l l o w t o D a i r y Cows. J . D a i r y S c i . 63: 5 4 5 - 5 5 2 . K r o n f e l d , D.S. a n d S. D o n o g h u e . 1980. D i g e s t i b i l i t y a n d A s s o c i a t i v e E f f e c t s o f P r o t e c t e d T a l l o w . J . D a i r y S c i . 6 3 : 6 4 2 - 6 4 5 . L e a t , W.M.F. ' a n d F.A. H a r r i s o n . 1975. " D i g e s t i o n , A b s o r p t i o n a n d T r a n s p o r t o f L i p i d s i n t h e S h e e p , " i n D i g e s t i o n a n d  M e t a b o l i s m i n t h e R u m i n a n t . I.W. M c D o n a l d a n d A . C . I . W a r n e r ( e d s . ) . A r m i d a l e : U. o f New E n g l a n d P u b l . U n i t , p p . 4 8 1 -495. L e n g , R.A. 1 9 7 0 . " F o r m a t i o n a n d P r o d u c t i o n o f V o l a t i l e F a t t y A c i d s i n t h e Rumen," i n P h y s i o l o g y o f D i g e s t i o n a n d  M e t a b o l i s m i n t h e R u m i n a n t . P r o c . o f 3 r d I n t e r n a t l . Symp. A.T. P h i l l i p s o n ( e d . ) . C a m b r i d g e : O r i e l P r e s s L t d . p p . 4 0 6 - 4 2 1 . L i n z e l l , J . L . , E . F . A n n i s o n , S. F a z a k e r l e y a n d R.A. L e n g . 1967. The I n c o r p o r a t i o n o f A c e t a t e , S t e a r a t e a n d D ( - ) p-OH-B u t y r a t e i n t o M i l k F a t by t h e I s o l a t e d P e r f u s e d Mammary G l a n d o f t h e G o a t . B i o c h e m . J . 104: 34 - 4 2 . L o u g h , A.K. 1970. " A s p e c t s o f L i p i d D i g e s t i o n i n t h e R u m i n a n t , " i n P h y s i o l o g y o f D i g e s t i o n a n d M e t a b o l i s m i n t h e R u m i n a n t . A . T . P h i l l i p s o n ( e d . ) . N e w c a s t l e u p o n T y n e : O r i e l P r e s s , p p . 5 1 9 - 5 2 8 . L o u g h , A.K. 1975. " C h e m i c a l a n d P h y s i c o - c h e m i c a l C h a n g e s o f ' F a t t y A c y l G r o u p s i n t h e G u t o f t h e S h e e p , " i n D i g e s t i o n a n d  M e t a b o l i s m i n t h e R u m i n a n t . I.W. M c D o n a l d a n d A . C . I . W a r n e r ( e d s . ) . A r m i d a l e : U. o f New E n g l a n d P u b l . U n i t , p p . 5 1 9 -528. M c C a r t o r , M.M. a n d G . C S m i t h . 1978. E f f e c t o f P r o t e c t e d L i p i d s on F e e d l o t P e r f o r m a n c e a n d C a r c a s s C h a r a c t e r i s t i c s o f S h o r t - F e d S t e e r s . J . A n i m . S c i . 4 7 : 2 7 0 - 2 7 5 . 1 48 M a c l e o d , G.K. a n d J . G . B u c h a n a n - S m i t h . 1972. D i g e s t i b i l i t y o f H y d r o g e n a t e d T a l l o w , S a t u r a t e d F a t t y A c i d s a n d S o y b e a n O i l -S u p p l e m e n t e d D i e t s by S h e e p . J . A n i m . S c i . 35: 8 9 0 - 8 9 5 . M a c l e o d , G.K. a n d A . S . Wood. 1972. I n f l u e n c e o f Amount a n d D e g r e e o f S a t u r a t i o n o f D i e t a r y F a t on Y i e l d a n d Q u a l i t y o f M i l k . J . D a i r y S c i . 55: 4 3 9 - 4 4 5 . M a c l e o d , G.K., Y. Y u a n d L.R. S c h a e f f e r . 1977. F e e d i n g V a l u e o f P r o t e c t e d A n i m a l T a l l o w f o r H i g h Y i e l d i n g D a i r y Cows. J . D a i r y S c i . 6 0 : 7 2 6 - 7 3 8 . M a t a - H e r n a n d e z , A., F.D. D r y d e n , J . A . M a r c h e l l o a n d L.H. S h e l l . 1978. P r o t e i n P r o t e c t e d F a t f o r R u m i n a n t s . I V . I n s u l i n a n d D e p o t F a t C o m p o s i t i o n o f Lambs. J . A n i m . S c i . 46: 1338-1 345. M a t t o s , W. a n d D.L. P a l m q u i s t . 1974. I n c r e a s e d P o l y u n s a t u r a t e d F a t t y A c i d Y i e l d s i n M i l k o f Cows F e d P r o t e c t e d F a t . J . D a i r y S c i . 5 7 : 1 0 5 0-1054. M e l l e n b e r g e r , R.W., D.E. Bauman a n d D.R. N e l s o n . 1973. M e t a b o l i c A d a p t a t i o n s d u r i n g L a c t o g e n e s i s . B i o c h e m . J . 136: 7 4 1 - 7 4 8 . M e r c e r , J.R., a n d E . F . A n n i s o n . 1976. " U t i l i z a t i o n o f N i t r o g e n i n R u m i n a n t s , " i n P r o t e i n M e t a b o l i s m a n d N u t r i t i o n . D . J .A. C o l e ( e d . ) . L o n d o n : B u t t e r w o r t h s , p p . 3 9 6 - 4 1 6 . M i n i s t r y o f A g r i c u l t u r e , F i s h e r i e s a n d F o o d . 1973. T h e A n a l y s i s o f A g r i c u l t u r a l M a t e r i a l s . A M a n u a l o f t h e A n a l y t i c a l M e t h o d s u s e d by t h e A g r i c u l t u r a l D e v e l o p m e n t a n d A d v i s o r y S e r v i c e . T e c h n i c a l B u l l . 27. L o n d o n : H e r M a j e s t y ' s S t a t i o n e r y O f f i c e . N a t i o n a l Academy o f S c i e n c e s . 1971. A t l a s o f N u t r i t i o n a l D a t a on U n i t e d S t a t e s a n d C a n a d i a n F e e d s . W a s h i n g t o n : N a t i o n a l Academy o f S c i e n c e s . N a t i o n a l Academy o f S c i e n c e s , 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 R e q u i r e m e n t s o f D a i r y C a t t l e . 5 t h e d . W a s h i n g t o n , D . C : N a t i o n a l Academy o f S c i e n c e s . N o b l e , R . C 1978. D i g e s t i o n , A b s o r p t i o n a n d T r a n s p o r t o f L i p i d s i n R u m i n a n t A n i m a l s . P r o g . i n L i p i d R e s . 17: 5 5 -9 1 • P a l m q u i s t , D.L. 1976. A K i n e t i c C o n c e p t o f L i p i d T r a n s p o r t i n R u m i n a n t s . A R e v i e w . J . D a i r y S c i . 59: 3 5 5 - 3 6 3 . P a l m q u i s t , D.L. a n d H.R. C o n r a d . 1971. O r i g i n o f P l a s m a F a t t y A c i d s i n L a c t a t i n g Cows f e d H i g h G r a i n o r H i g h F a t D i e t s . J . D a i r y S c i . 54: 1 0 2 5 - 1 0 3 3 . 149 P a l m q u i s t , D.L., K.E. M c C l u r e a n d C F . P a r k e r . 1977. E f f e c t o f P r o t e c t e d S a t u r a t e d o r P o l y u n s a t u r a t e d F a t f e d t o P r e g n a n t a n d L a c t a t i n g Ewes on M i l k C o m p o s i t i o n , Lamb F a t t y A c i d s a n d G r o w t h . J . A n i m . S c i . 4 5 : 1 1 5 2 - 1 1 5 9 . P a l m q u i s t , D.L. a n d H.R. C o n r a d . 1978. H i g h F a t R a t i o n s f o r D a i r y Cows. E f f e c t s on F e e d I n t a k e , M i l k a n d F a t P r o d u c t i o n , a n d P l a s m a M e t a b o l i t e s . J . D a i r y S c i . 6 1 : 8 9 0 - 9 0 1 . P a l m q u i s t , D.L. a n d W i l s o n M a t t o s . 1978. T u r n o v e r o f L i p o p r o t e i n s a n d T r a n s f e r t o M i l k F a t o f D i e t a r y ( 1 - C a r b o n -14) L i n o l e i c A c i d i n L a c t a t i n g Cows. J . D a i r y S c i . 6 1 : 5 6 1 - 5 6 5 . P a l m q u i s t , D.L. a n d H.R. C o n r a d . 1980. H i g h F a t R a t i o n s f o r D a i r y Cows. J . D a i r y S c i . 63: 3 9 1 - 3 9 5 . P a l m q u i s t , D.L. a n d T . C J e n k i n s . 1980. F a t i n L a c t a t i o n R a t i o n s : R e v i e w . J . D a i r y S c i . 63: 1-14. P a r k i n s o n , J . A . a n d S.E. A l l a n . 1975. A Wet O x i d a t i o n P r o c e d u r e S u i t a b l e f o r t h e D e t e r m i n a t i o n o f N i t r o g e n a n d 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 . a n d P l a n t A n a l y s i s . 6: 1-11. P e n n i n g t o n , R . J . 1952. T h e M e t a b o l i s m o f S h o r t - C h a i n F a t t y A c i d s i n t h e S h e e p . I . F a t t y A c i d U t i l i z a t i o n a n d K e t o n e B o d y P r o d u c t i o n by Rumen E p i t h e l i u m a n d o t h e r T i s s u e s . B i o c h e m . J . 5 1 : 2 5 1 - 2 5 8 . P e r r y , T.W., W.M. B e e s o n , M.T. M o h l e r a n d E . B a u g h . 1976. V a l u e o f A d d e d F a t i n H i g h M o i s t u r e B e e f C a t t l e D i e t s a n d i n D r y Lamb D i e t s . J . A n i m . S c i . 43: 9 4 5 - 9 5 1 . Plowman, R.D., J . B i t m a n , C H . G o r d o n , L . P . D r y d e n , H.K. G o e r i n g , T.R. Wrenn, L . F . E d m o n d s o n , R.A. Y o n c o s k i e a n d F.W. D o u g l a s , J r . 1972. M i l k F a t w i t h I n c r e a s e d P o l y u n s a t u r a t e d F a t t y A c i d s . J . D a i r y S c i . 55: 2 0 4 - 2 0 7 . R e i s , P . J . a n d P.G. S c h i n c k e l . 1963. Some E f f e c t s o f S u l p h u r -C o n t a i n i n g A mino A c i d s on t h e G r o w t h a n d C o m p o s i t i o n o f W o o l . A u s t . J . B i o l . S c i . 16: 218. R e i s e r , R. a n d K.A. K u i k e n . 1951. H y d r o g e n a t i o n o f P o l y u n s a t u r a t e d F a t t y A c i d s by t h e R u m i n a n t . F e d . P r o c . 10: 236. ( A b s t r . ) . R i n d s i g , R.B. a n d L.H. S h u l t z . 1974. E f f e c t o f Amount a n d F r e q u e n c y o f F e e d i n g S a f f l o w e r O i l on R e l a t e d M i l k B l o o d a n d Rumen C o m p o n e n t s . J . D a i r y S c i . 57: 1 0 3 7 - 1 0 4 5 . R h o d e s , R . C , I I I , M.M. M c C a r t o r a n d R.D. R a n d e l . 1978. E f f e c t o f F e e d i n g P r o t e i n - P r o t e c t e d L i p i d u p on G r o w t h a n d 150 R e p r o d u c t i v e D e v e l o p m e n t o f Y e a r l i n g H e i f e r s . J . A n i m . S c i . 46: 7 6 9 - 7 7 7 . R o b i n s o n , D.S. 1970. " A s s i m i l a t i o n , D i s t r i b u t i o n a n d S t o r a g e . S e c t i o n C. T h e F u n c t i o n o f t h e P l a s m a T r i g l y c e r i d e s i n F a t t y A c i d T r a n s p o r t , " i n C o m p r e h e n s i v e B i o c h e m i s t r y : L i p i d  M e t a b o l i s m , V o l . 18. M. F l o r k i n a n d E.H. S t o t z ( e d s . ) . A m s t e r d a m : E l s e v i e r P u b l . C o . , p p . 5 1 - 1 1 6 . Rook, J . A . F . a n d P.C. T h omas. 1969. "The S i g n i f i c a n c e o f Rumen A c t i v i t y , " i n P r o c . o f t h e 3 r d N u t r . C o n f . f o r F e e d  M a n u f a c t u r e r s . W. Swan a n d D. L e w i s ( e d s . ) . L o n d o n : J . & A. C h u r c h i l l L t d . , p p . 2-21. R o s s , J . P . a n d W.D. K i t t s . 1971. I m p r o v e d M e t h o d f o r t h e D e t e r m i n a t i o n o f V o l a t i l e F a t t y A c i d s i n R u m i n a n t B l o o d P l a s m a . J . D a i r y S c i . 54: 1 8 2 4 - 1 8 3 1 . R o y a l C o l l e g e o f P h y s i c i a n s o f L o n d o n a n d t h e B r i t i s h C a r d i a c S o c i e t y . 1976. P r e v e n t i o n o f C o r o n a r y H e a r t D i s e a s e . J . R o y . C o l l . P h y c n s 10: 1-63. S chwab, C.G., L.D. S a t t e r a n d A.B. C l a y . 1976. R e s p o n s e o f L a c t a t i n g D a i r y Cows t o A b o m a s a l I n f u s i o n o f A mino A c i d s . J . D a i r y S c i . 59: 1 2 5 4 - 1 2 7 0 . S c o t t , T.W., L . J . C o o k , K.A. F e r g u s o n , I.W. M c D o n a l d , R.A. B u c h a n a n a n d G. L o f t u s H i l l s . 1970. P r o d u c t i o n o f P o l y u n s a t u r a t e d M i l k F a t i n D o m e s t i c R u m i n a n t s . A u s t . J . S c i . 32: 2 9 1 - 2 9 3 . S c o t t , T.W., L . J . Cook a n d S.C. M i l l s . 1971. P r o t e c t i o n o f D i e t a r y P o l y u n s a t u r a t e d F a t t y A c i d s A g a i n s t M i c r o b i a l H y d r o g e n a t i o n i n R u m i n a n t s . J . Amer. O i l Chem. S o c . 4 8 : 3 5 8 - 3 6 4 . S c o t t , T.W., P . J . Brumby, A . J . R o y a l a n d L . J . C o o k . 1972. O i l S e e d S u p p l e m e n t s f o r t h e P r o d u c t i o n o f P o l y u n s a t u r a t e d R u m i n a n t M i l k F a t . S e a r c h 3: 1 7 0 - 1 7 1 . S c o t t , T.W., a n d L . J . C o o k . 1975. " E f f e c t o f D i e t a r y F a t on L i p i d M e t a b o l i s m i n R u m i n a n t s , " i n D i g e s t i o n a n d M e t a b o l i s m  i n t h e R u m i n a n t . I.W. M c D o n a l d a n d A . C . I . W a r n e r ( e d s . ) . A r m i d a l e : U. o f New E n g l a n d P u b l . U n i t , p p . 5 1 0 - 5 2 3 . S e e l e y , R.C., D.G. A r m s t r o n g a n d J . C . M a c r a e . 1969. " F e e d C a r b o h y d r a t e s - T h e C o n t r i b u t i o n o f t h e E n d - P r o d u c t s o f t h e i r D i g e s t i o n t o E n e r g y S u p p l y i n t h e R u m i n a n t , " i n E n e r g y  M e t a b o l i s m o f F a r m A n i m a l s . P r o c . o f t h e 4 t h Symp., E u r o p e a n A s s o c . f o r A n i m . P r o d . , P u b l . No. 12. Warsaw: O r i e l P r e s s L t d . , p p . 9 3 - 1 0 2 . S e i n e r , D.R. a n d L.H. S c h u l t z . 1980. E f f e c t s o f F e e d i n g O l e i c A c i d o r H y d r o g e n a t e d V e g e t a b l e O i l s t o L a c t a t i n g Cows. J . 151 D a i r y S c i . 63: 1 2 3 5 - 1 2 4 1 . S h a f f e r , L . , J.D. R o u s s e l a n d K . L . K o o n c e . 1981. E f f e c t s o f A g e , T e m p e r a t u r e - S e a s o n , a n d B r e e d on B l o o d C h a r a c t e r i s t i c s o f D a i r y C a t t l e . J . D a i r y S c i . 64: 6 2 - 7 0 . S h a r m a , H.R., J.R. I n g a l l s a n d J . A . M c K i r d y . 1978. R e p l a c i n g B a r l e y w i t h P r o t e c t e d T a l l o w i n R a t i o n s o f L a c t a t i n g H o l s t e i n Cows. J . D a i r y S c i . 6 1 : 5 7 4 - 5 8 3 . S h e l l , L.A., F.D. D r y d e n , A. M a t a - H e r n a n d e z a n d W.H. H a l e . 1978. P r o t e i n P r o t e c t e d F a t f o r R u m i n a n t s . I I I . D i g e s t i o n a n d P e r f o r m a n c e o f Lambs. J . A n i m . S c i . 46: 1 3 3 2 - 1 3 3 7 . S h o r l a n d , F.B., R.O. W e e n i n k , A . I . J o h n s a n d I . R.C. M c D o n a l d . 1957. T h e E f f e c t o f S h e e p Rumen C o n t e n t s on U n s a t u r a t e d F a t t y A c i d s . B i o c h e m . J . 6 7 : 3 2 8 - 3 3 3 . S i d h u , G.S. a n d J.R. A s h e s . 1977. P r o c . N u t r . S o c . A u s t . 2: 66. S m i t h , N.E., W.L. D u n k l e y a n d A.A. F r a n k e . 1978. E f f e c t s o f F e e d i n g P r o t e c t e d T a l l o w t o D a i r y Cows i n E a r l y L a c t a t i o n . J . D a i r y S c i . 6 1 : 7 4 7 - 7 5 6 . S m i t h , R.H. 1969. R e v i e w s o f t h e P r o g r e s s o f D a i r y S c i e n c e . N i t r o g e n M e t a b o l i s m a n d t h e Rumen. J . D a i r y R e s . 36: 3 1 3 -331 . S m i t h , R.H. 1975. " N i t r o g e n M e t a b o l i s m i n t h e Rumen a n d the. C o m p o s i t i o n a n d N u t r i t i v e V a l u e o f N i t r o g e n Compounds E n t e r i n g t h e Duodenum," i n D i g e s t i o n a n d M e t a b o l i s m i n t h e  R u m i n a n t . I.W. M c D o n a l d a n d A . C . I . W a r n e r ( e d s . ) . A r m i d a l e : T h e U. o f New E n g l a n d P u b l . U n i t , p p . 3 9 9 - 4 1 5 . S m i t h , S., D . J . E a s t e r a n d R. D i l s . 1966. F a t t y A c i d B i o s y n t h e s i s . I I I . I n t r a c e l l u l a r S i t e o f E n z y m e s i n L a c t a t i n g - R a b b i t Mammary G l a n d . B i o c h i m . B i o p h y s . A c t a 125: 4 4 5 - 4 5 5 . S t e e l , R.G.D. a n d J . H . T o r r i e . 1960. P r i n c i p l e s a n d P r o c e d u r e s o f S t a t i s t i c s . M c G r a w - H i l l : New Y o r k . S t o r r y , J . E . 1970. R e v i e w s o f t h e P r o g r e s s o f D a i r y S c i e n c e . S e c t i o n A. P h y s i o l o g y . R u m i n a n t M e t a b o l i s m i n R e l a t i o n t o t h e S y n t h e s i s a n d S e c r e t i o n o f M i l k F a t . J . D a i r y R e s . 37: 1 3 9-164. S t o r r y , J . E . 1972. M i l k F a t : I t s S y n t h e s i s a n d C o m p o s i t i o n i n R e l a t i o n t o t h e N u t r i t i o n o f t h e D a i r y Cow. J . S o c . D a i r y T e c h n o l . 2 5 : 4 0 - 4 6 . S t o r r y , J . E . 1980. I n f l u e n c e o f N u t r i t i o n a l F a c t o r s on t h e Y i e l d a n d C o n t e n t o f M i l k F a t : N o n - P r o t e c t e d F a t i n t h e 152 D i e t , " i n F a c t o r s A f f e c t i n g t h e Y i e l d s a n d C o n t e n t s o f M i l k  C o n s t i t u e n t s o f C o m m e r c i a l I m p o r t a n c e . I n t e r n a t l . D a i r y F e d . D ocument 125, p p . 8 8 - 9 5 . S t o r r y , J . E . a n d J . A . F . R o o k . 1964. P l a s m a T r i g l y c e r i d e s a n d M i l k - F a t S y n t h e s i s . B i o c h e m . J . 9 1 : 2 7 C - 2 9 C . S t o r r y , J . E . , A . J . H a l l a n d V.W. J o h n s o n . 1973. T h e E f f e c t s o f I n c r e a s i n g A m o u n t s o f D i e t a r y T a l l o w on M i l k F a t S e c r e t i o n i n t h e Cow. J . D a i r y R e s . 40: 2 9 3 - 2 9 9 . S t o r r y , J . E . , P.E. Brumby, A . J . H a l l a n d V.W. J o h n s o n . 1974a. R e s p o n s e s i n Rumen F e r m e n t a t i o n a n d M i l k - F a t S e c r e t i o n i n Cows R e c e i v i n g L o w-Roughage D i e t s S u p p l e m e n t e d w i t h P r o t e c t e d T a l l o w . J . D a i r y R e s . 4 1 : 165-173. S t o r r y , J . E . , P.E. Brumby, A . J . H a l l a n d V.W. J o h n s o n . 1974b. R e s p o n s e o f t h e L a c t a t i n g Cow t o D i f f e r e n t M e t h o d s o f I n c o r p o r a t i n g C a s e i n a n d C o c o n u t O i l i n t h e D i e t . J . D a i r y S c i . 57: 6 1 - 6 7 . S t o r r y , J . E . , P.E. Brumby, A . J . H a l l a n d B. T u c k l e y . 1 9 7 4 c . E f f e c t s o f F r e e a n d P r o t e c t e d F o r m s o f C o d l i v e r O i l on M i l k F a t S e c r e t i o n i n t h e D a i r y Cow. J . D a i r y S c i . 57: 1046-1 050. S t o r r y , J . E . , P.E. Brumby a n d W.L. D u n k l e y . 1980. " I n f l u e n c e o f N u t r i t i o n a l F a c t o r s on t h e Y i e l d a n d C o n t e n t o f M i l k F a t : P r o t e c t e d N o n - P o l y u n s a t u r a t e d F a t i n t h e D i e t , " i n F a c t o r s  A f f e c t i n g t h e Y i e l d s a n d C o n t e n t s o f M i l k C o n s t i t u e n t s o f  C o m m e r c i a l I m p o r t a n c e . I n t e r n a t l . D a i r y f e d . D o c u m e n t 125, p p . 105-125. S u t t o n , J .D., J . E . S t o r r y a n d J.W.G. N i c h o l s o n . 1970. T h e D i g e s t i o n o f F a t t y A c i d s i n t h e S t o m a c h a n d I n t e s t i n e s o f S h e e p G i v e n W i d e l y D i f f e r e n t R a t i o n s . J . D a i r y R e s . 37: 9 7 - 1 0 5 . S u t t o n , J . D. 1980. " I n f l u e n c e o f N u t r i t i o n a l F a c t o r s on t h e Y i e l d a n d C o n t e n t o f M i l k F a t : D i e t a r y C o m p o n e n t s o t h e r t h a n F a t " , i n F a c t o r s A f f e c t i n g t h e Y i e l d s a n d C o n t e n t s o f M i l k  C o n s t i t u e n t s o f C o m m e r c i a l I m p o r t a n c e . I n t e r n a t l . D a i r y F e d . D ocument 125, p p . 126-134. Tamminga, S. 1980. "Amino A c i d S u p p l y a n d U t i l i z a t i o n i n R u m i n a n t s , " i n P r o c . o f t h e 3 r d Symp. on P r o t e i n M e t a b o l i s m  a n d N u t r i t i o n , E u r o p e a n A s s o c . f o r A n i m . P r o d . , P u b l . No. 27. H . J . O s l a g e a n d K. R o h r ( e d s . ) . B r a u n s c h w e i g , G e r m a n y : I n f o . C e n t r e o f B u n d e s f o r s c h u n g s a n s t a l t f u r L a n d w u r t s c h a f t , p p . 3 7 9 - 3 9 5 . Thomas, P.C. 1980. " I n f l u e n c e o f N u t r i t i o n on t h e Y i e l d a n d C o n t e n t o f P r o t e i n i n M i l k : D i e t a r y P r o t e i n a n d E n e r g y S u p p l y , " i n F a c t o r s A f f e c t i n g t h e Y i e l d s a n d C o n t e n t s o f 153 M i l k C o n s t i t u e n t s o f C o m m e r c i a l I m p o r t a n c e . I n t e r n a t l . D a i r y F e d . Document 125, p p . 1 4 2 - 1 5 1 . Thomas, P.C., J . S . C h a l m e r s , D.G. C h a m b e r l a i n a n d N. B e l i b a s a k i s . 1980. "The E f f e c t o f D i e t on t h e C o n t e n t a n d C o m p o s i t o n o f C r u d e P r o t e i n i n M i l k , " i n P r o c . o f t h e 3 r d  E u r o p e a n A s s o c . f o r A n i m . P r o d . Symp. on P r o t e i n M e t a b o l i s m a n d N u t r i t i o n . H . J . O s l a g e a n d K. R o h r ( e d s . ) . B r a u n s c h w e i g : I n f o . C e n t r e o f B u n d e s f o r s c h u n g s a n s t a l t f u r L a n d w u r t s c h a f t , p p . 5 2 2 - 5 2 8 . T y r r e l l , H.T. a n d J . T . R e i d . 1965. P r e d i c t i o n o f t h e E n e r g y V a l u e o f Cow's M i l k . J . D a i r y S c i . 48: 1 2 1 5 - 1 2 2 3 . V i k - M o , L . , R.S. Emery a n d J . T . H u b e r . 1974. M i l k P r o t e i n P r o d u c t i o n i n Cows A b o m a s a l l y I n f u s e d w i t h C a s e i n o r G l u c o s e . J . D a i r y S c i . 5 7 : 8 6 9 - 8 7 7 . V i v i a n i , R. 1970. M e t a b o l i s m o f L o n g - C h a i n F a t t y A c i d s i n t h e Rumen. A d v . L i p i d R e s . 8: 2 6 7 - 3 4 6 . W a l d e r n , D.E. 1971. A R a p i d M i c r o - D i g e s t i o n P r o c e d u r e f o r N e u t r a l a n d A c i d D e t e r g e n t F i b e r . C a n . J . A n i m . S c i . 51: 6 7 - 6 9 . Wrenn, T.R., J.R. W e y a n t , D.L. Wood, J . B i t m a n , R.M. R a w l i n g s a n d K.E. L y o n . 1976. I n c r e a s i n g P o l y u n s a t u r a t i o n o f M i l k F a t s by F e e d i n g F o r m a l d e h y d e P r o t e c t e d S u n f l o w e r - S o y b e a n S u p p l e m e n t . J . D a i r y S c i . 59: 6 2 7 - 6 3 5 . Wrenn, T.R., J . B i t m a n , J.R. W e y a n t , D.L. Wood, K.D. W i g g e r s a n d L . F . E d m o n d s o n . 1977. M i l k a n d T i s s u e L i p i d C o m p o s i t i o n A f t e r F e e d i n g Cows P r o t e c t e d P o l y u n s a t u r a t e d F a t f o r Two Y e a r s . J . D a i r y S c i . 60: 5 2 1 - 5 3 2 . Wrenn, T.R., J . B i t m a n , R.A. W a t e r m a n , J.R. W e y a n t , D.L. Wood, L . L . S t r o z i n s k i a n d N.W. H o o v e n , J r . 1978. F e e d i n g P r o t e c t e d a n d U n p r o t e c t e d T a l l o w t o L a c t a t i n g Cows. J . D a i r y S c i . 6 1 : 4 9 - 5 8 . Y a n g , Y.T., J.M. Rohde a n d R.L. B a l d w i n . 1978. D i e t a r y L i p i d M e t a b o l i s m i n L a c t a t i n g D a i r y Cows. J . D a i r y S c i . 6 1 : 1 4 0 0 - 1 4 0 6 . 1 54 V. APPENDIX T A B L E I . PREDICTED MEANS AND STANDARD ERRORS FOR S I G N I F I C A N T SOURCES OF V A R I A T I O N : INTAKES AND OUTPUTS - PERIOD I V A R I A B L E SOURCE OF V A R I A T I O N BREED L A C T A T I O N CATEGORY HO L S T E I N AYRSHIRE H E I F E R S >2ND L A C T INTAKES OUTPUTS MILK S . E . FCM S . E . SCM S . E . MILK G.E. S . E . MILK FAT S . E . MILK PROTEIN S . E . MILK LACTOSE S . E . (KG/COW/DAY) GRAIN 1 3.23 10.65 10.87 1 3.00 S . E . .263 .529 .456 .342 CUBES 5.89 5.05 5.08 5.86 S . E . .114 .220 .185 .120 F E E D 19.12 15.70 15.96 18.86 S . E . .362 .745 .635 .446 GRAIN C P . 2.11 1 .70 1 .73 2.07 S . E . .049 .085 .077 .057 CUBE C P . 1 .08 .91 .92 1 .07 S . E . .023 .042 .034 .028 TOTAL C P . 3.19 2.61 2.65 3.15 S . E . .068 .125 . 108 .080 TOTAL D.P. 2.38 1 .94 1 .98 2.35 S . E . .049 .096 .080 .062 GRAIN G.E. 242.9 195.5 199.8 238.7 S . E . 4.96 9.37 8.45 5.78 CUBE G.E. 109. 1 93.50 94. 1 5 1 08.5 S . E . 2.12 4.070 3.433 2.22 TOTAL G.E. 352.0 289.0 293.9 3 4 7 . 1 S . E . 6.79 1 3.35 1 1 .74 7.70 TOTAL D.E. 247.4 203.1 206.5 243.9 S . E . 4.83 9.31 8.27 5.32 29.58 1 .467 23.79 1 .274 25.33 1 .303 (KG/COW/DAY) 20.58 1 .533 17.75 1.211 18.66 1 .286 (MJ/COW/DAY) — 79.41 65.52 58.53 4.086 5.927 4.033 (KG/COW/DAY) — 23.03 2.500 20.00 1 .798 20.89 1 .890 NS .936 .0431 1 .565 .0809 NS .738 .0726 1 .203 .1317 .635 .0458 .669 .0497 1 .078 .0838 32.04 1.615 26.04 1 .260 27.56 1 .204 86.44 3.774 .882 .0475 1 .005 .0362 1 .690 .0847 T A B L E 11 . PREDICTED MEANS AND STANDARD ERRORS MILK F A T % - PERIOD I V A R I A B L E PREDICTED MEAN STANDARD ERROR MILK COMPONENT MILK F A T BREED HOLSTEINS AYRSHIRES L A C T A T I O N CATEGORY H E I F E R S >2ND L A C T A T I O N COWS 2.76 3.44 3.35 2.85 (%) .081 .199 .167 .107 B.X L INTERACTION H O L S T E I N H E I F E R S AYRSHIRE H E I F E R S H O L S T E I N >2ND LACT. AYRSHIRE >2ND LACT. COWS COWS 2.66 4.05 2.86 2.84 .097 .185 .074 .148 157 T A B L E I I I . PREDICTED MEANS AND STANDARD ERRORS FOR S I G N I F I C A N T SOURCES OF VARIATION: E F F I C I E N C Y RATIOS - PERIOD I E F F I C I E N C Y RATIO SOURCE OF V A R I A T I O N H E I F E R S >2ND LACT. COWS OUTPUT/ENERGY INPUT (KG/COW/DAY) -MILK/G.E. INTAKE .068 .092 S . E . .0039 .0037 FCM/G.E. INTAKE .060 .075 S . E . .0034 .0029 SCM/G.E. INTAKE .063 .079 S . E . .0035 .0027 MILK/D.E. INTAKE .406 .548 S.E. .0230 .0053 FCM/D.E. INTAKE .357 .445 S . E . .0202 .0170 SCM/D.E. INTAKE ..374 .472 S . E . .0206 .0156 (MJ/MJ) G.E. MILK/G.E. INTAKE .197 .248 S . E . .0109 .0083 G.E. MILK/D.E. INTAKE .280 .354 S . E . .0154 .0117 OUTPUT/PROTEIN INPUT (KG/KG) M I L K / C P . INTAKE 7.57 10.15 S . E . .440 .394 FCM/C.P. INTAKE 6.64 8.26 S . E . .383 .317 SCM/C.P. INTAKE 6.96 8.75 S.E. .393 .291 MILK/D.P. INTAKE 10.18 13.63 S . E . .599 .531 FCM/D.P. INTAKE 8.94 11.09 S . E . .528 .437 SCM/D.P. INTAKE 9.34 11.74 S.E. .538 .400 (MJ/KG) G.E. M I L K / C P . INTAKE 21 .82 27.43 S . E . 1.232 .913 G.E. MILK/D.P. INTAKE 7.02 8.80 S . E . .403 .300 158 T A B L E I V . PREDICTED MEANS AND STANDARD ERRORS FOR S I G N I F I C A N T SOURCES OF V A R I A T I O N : APPARENT ETHER EXTRACT D I G E S T I B I L I T Y PERIOD I PREDICTED STANDARD MEAN ERROR E . E . APPARENT D I G E S T I B I L I T Y T X L I NTERACTION CONTROL H E I F E R S 74.64 .850 PROTEC S H E I F E R S 77.98 .380 PROTEC R H E I F E R S 85.66 1.760 CONTROL >2ND L A C T . COWS 68.64 .270 PROTEC S >2ND L A C T . COWS 81.74 .825 PROTEC R >2ND L A C T . COWS 81.67 0.0 T A B L E V. PREDICTED MEAN % APPARENT D I G E S T I B I L I T I E S (DRY MATTER B A S I S ) : C O L L E C T I O N - DAYS 1-4 ORTHOGONAL TREATMENT CONTRAST (C) ( S ) VS. V S . COMPONENT CONTROL PROTEC S PROTEC R (S+R) (R) ( % )  DRY MATTER 71.23 71.24 71.61 NS NS S. E . .776 .642 1.749 ORGANIC MATTER 72.41 72.39 72.98 NS NS S. E . .842 1.897 1.658 GROSS ENERGY 69.86 70.40 70.52 NS NS S. E . .798 .799 1.917 ETHER EXTRACT 71.34 80.66 84.30 NS P<.05 S. E . 1.847 1.360 1.827 NITROGEN 75.93 73.08 74.57 NS NS S. E . .710 1.250 1.365 ACID-DETERGENT F I B R E 37.58 42.70 40.79 NS NS S. E . 4.940 2.424 2.610 TOTAL ASH 54.44 54.70 51.95 NS NS S . E . 2.419 1.770 1.968 CALCIUM 32.12 33.47 26.51 NS NS S. E . 4.270 3.296 3.846 PHOSPHORUS 42.43 47.81 45.39 NS NS S. E . 5.879 4.705 6.394 MAGNESIUM 38.17 40.37 39.08 NS NS S . E . 1.626 2.829 3.812 NS: NOT S I G N I F I C A N T T A B L E V I . PREDICTED MEANS AND STANDARD ERRORS FOR S I G N I F I C A N T SOURCES OF V A R I A T I O N : BLOOD METABOLITES - PERIOD I PREDICTED STANDARD METABOLITE MEAN ERROR GLUCOSE (MG %) L A C T A T I O N CATEGORY H E I F E R S 68.3 .68 >2ND L A C T A T I O N COWS 61.9 .77 N O N - E S T E R I F I E D F A T T Y ACIDS U M O L E / L ) L A C T A T I O N CATEGORY H E I F E R S 250.3 12.89 >2ND L A C T A T I O N COWS 305.9 16.79 T X L INTERACTION CONTROL H E I F E R S 213.6 11.71 PROTEC S H E I F E R S 320.2 29.22 PROTEC R H E I F E R S 217.1 14.64 CONTROL >2ND L A C T . COWS 247.2 27.26 PROTEC S >2ND L A C T . COWS 319.0 20.35 PROTEC R >2ND L A C T . COWS 351.6 31.42 T A B L E V I I . PREDICTED MEANS AND STANDARD ERRORS FOR S I G N I F I C A N T SOURCES OF V A R I A T I O N : INTAKES AND OUTPUTS - PERIOD I I V A R I A B L E SOURCE OF V A R I A T I O N BREED L A C T A T I O N CATEGORY H O L S T E I N AYRSHIRE H E I F E R S >2ND L A C T INTAKES (KG/COW/DAY) GRAIN 14.62 11.14 1 1 .72 14.05 S . E . .373 .818 .580 .816 CUBES 6.25 4.93 5.10 6.08 S . E . .179 .318 .237 .309 F E E D 20.87 16.07 16.81 20. 1 3 .544 1.133 .812 1.119 GRAIN C P . S . E . CUBE C P . S . E . TOTAL C P , S . E . GRAIN G.E. S . E . CUBE G.E. S . E . TOTAL G.E. S . E . OUTPUTS MILK S . E . FCM S . E . SCM S.E. 2.40 .061 1.13 .033 3.53 .092 263, 6, 115, 3, 379, 9, 6 73 6 32 3 89 28.39 1 .520 20.73 1.185 22.86 1 .259 1 .83 . 1 34 .894 .0578 2.72 .191 92 095 925 0432 85 1 37 (MJ/COW/DAY) 200.9 14.75 91 .22 5.890 29 2 . 1 20.56 211.2 1 0.45 94.31 4 305 399 5 1 4.75 (KG/COW/DAY) 19, 2, 15, 1 , 16, 1 4 288 52 491 80 18, 1 , 14, 1 , 87 687 39 126 1 .688 1 5.83 1 .294 31 134 1 04 ,0561 ,41 ,189 253.3 14.70 112.5 5.72 365.8 20.32 28.66 1 .969 21 .86 1.165 23.83 1 .270 (MJ/COW/DAY) MILK G.E. S . E . 71.67 52.68 49.62 74.73 3.946 5.297 4.058 3.979 T A B L E V I I I . PREDICTED MEANS AND STANDARD ERRORS FOR S I G N I F I C A N T SOURCES OF V A R I A T I O N : ENERGY E F F I C I E N C Y RATIOS - PERIOD I I PREDICTED STANDARD RATIO MEAN ERROR MIL K / G . E . INTAKE (KG/MJ) BREED H O L S T E I N .074 .0032 AYRSHIRE .063 .0049 L A C T A T I O N CATEGORY H E I F E R S .059 .0034 >2ND L A C T A T I O N COWS .078 .0033 FCM/G.E. I N T A K E " L A C T A T I O N CATEGORY H E I F E R S .046 .0025 >2ND L A C T A T I O N COWS .060 .0024 T X L INTERACTION CONTROL H E I F E R S .035 .0044 PROTEC S H E I F E R S . .056 .0024 PROTEC R H E I F E R S .048 .0030 CONTROL >2ND L A C T . COWS .056 .0038 PROTEC S >2ND L A C T . COWS .056 .0021 PROTEC R >2ND L A C T . COWS .069 .0020 SCM/G.E. INTAKE L A C T A T I O N CATEGORY H E I F E R S .051 .0027 >2ND L A C T A T I O N COWS .065 .0019 T X L INTERACTION CONTROL H E I F E R S .039 .0058 PROTEC S H E I F E R S .059 .0019 PROTEC R H E I F E R S .054 .0041 CONTROL >2ND L A C T . COWS .061 .0029 PROTEC S >2ND L A C T . COWS .061 .0021 PROTEC R >2ND L A C T . COWS .074 .0006 G.E. MILK/G.E. INTAKE (MJ/MJ) L A C T A T I O N CATEGORY H E I F E R S .159 .0020 >2ND L A C T A T I O N COWS .205 .0015 T X L INTERACTION CONTROL H E I F E R S .123 .0043 PROTEC S H E I F E R S .185 .0014 PROTEC R H E I F E R S .169 .0030 CONTROL >2ND L A C T . COWS .192 .0022 PROTEC S >2ND L A C T . COWS .192 .0016 PROTEC R >2ND L A C T . COWS .232 .0005 T A B L E I X . PREDICTED MEANS AND STANDARD ERRORS FOR S I G N I F I C A N T SOURCES OF V A R I A T I O N : PROTEIN E F F I C I E N C Y RATIOS - PERIOD I I PREDICTED STANDARD MEAN ERROR M I L K / C P . INTAKE (KG/KG) BREED H O L S T E I N 7.98 .340 AYRSHIRE 6.78 .519 LA C T A T I O N CATEGORY H E I F E R S 6.36 .367 >2ND L A C T A T I O N COWS 8.40 .349 FCM/C.P. INTAKE L A C T A T I O N CATEGORY H E I F E R S 4.98 .264 >2ND L A C T A T I O N COWS 6.45 .254 T X L INTERACTION CONTROL H E I F E R S 3.76 .479 PROTEC S H E I F E R S 5.99 .252 PROTEC R H E I F E R S 5.18 .327 CONTROL >2ND L A C T . COWS 5.96 .407 PROTEC S >2ND L A C T . COWS 5.98 .221 PROTEC R >2ND L A C T . COWS 7.42 .210 SCM/C.P. INTAKE L A C T A T I O N CATEGORY H E I F E R S 5.43 .284 >2ND L A C T A T I O N COWS 7.02 .207 T X L INTERACTION CONTROL H E I F E R S 4.19 .620 PROTEC S H E I F E R S 6.34 .202 PROTEC R H E I F E R S 5.78 .434 CONTROL >2ND L A C T . COWS 6.56 .305 PROTEC S >2ND L A C T . COWS 6.57 .220 PROTEC R >2ND L A C T . COWS 7.93 .061 G.E. M I L K / C P . INTAKE (MJ/KG) L A C T A T I O N CATEGORY H E I F E R S 17.04 .890 >2ND L A C T A T I O N COWS 22.02 .649 T X L INTERACTION CONTROL H E I F E R S 13.14 1.944 PROTEC S H E I F E R S 19.86 .634 PROTEC R H E I F E R S 18.12 1.362 CONTROL >2ND L A C T . COWS 20.56 .956 PROTEC S >2ND L A C T . COWS 20.61 .691 PROTEC R >2ND L A C T . COWS 24.87 .190 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

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.831.1-0095518/manifest

Comment

Related Items