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UBC Theses and Dissertations

A genetic evaluation of some serum and milk production traits of dairy cattle Nash, Thomas Edward 1978

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A GENETIC EVALUATION OF SOME SEBUM AND MILK PRODUCTION TRAITS OF DAISY CATTLE by THOMAS EDWARD NASH B.Sc. (Agr.), U n i v e r s i t y of B r i t i s h Columbia, 1576 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE GF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES (Department of Animal Science) 8e accept t h i s t h e s i s as conforming to t h e r e q u i r e d standard. THE UNIVERSITY OF BRITISH COLUMBIA October, 1978 (c) Thomas Edward Nash, 1978 In presenting th i s thes is in pa r t i a l fu l f i lment of the requirements for an advanced degree at the Univers i ty of B r i t i s h Columbia, I agree that the L ibrary sha l l make it f ree ly ava i lab le for reference and study. I further agree that permission for extensive copying of th i s thesis for scho lar ly purposes may be granted by the Head of my Department or by his representat ives. It is understood that copying or pub l i ca t ion of th is thes is for f inanc ia l gain shal l not be allowed without my written permission. Department of Animal Science The Univers i ty of B r i t i s h Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date f i i i AESTBACT T h i s study was i n i t i a t e d to eva l u a t e the g e n e t i c aspects o f c e r t a i n serum c o n s t i t u e n t s and milk production t r a i t s of d a i r y c a t t l e . The p o p u l a t i o n under study was l o c a t e d on commercial d a i r y farms i n the upper F r a s e r V a l l e y r e g i o n c f B r i t i s h Columbia. Serum samples from 545 animals were used i n the a n a l y s i s . T h i s represented 27 s i r e groups with approximately 20 samples per group. Serum c o n s t i t u e n t s analysed were c a l c i u m , i n o r g a n i c phosphate, glucose, BOS, u r i c a c i d , c h o l e s t e r o l , t o t a l p r o t e i n , albumin, b i l i r u b i n , a l k a l i n e phosphatase, SGGT, c r e a t i n i n e , t r i g l y c e r i d e s , sodium, potassium, c h l o r i d e , b i c a r b o n a t e , t h y r o x i n e and amylase, Pro d u c t i o n t r a i t s s t u d i e d were milk, milk f a t and milk p r o t e i n f o r both f i r s t l a c t a t i o n and the l a c t a t i o n i n progress at time of serum sampling. S e v e r a l e f f e c t s were re c o g n i z e d as having a p o t e n t i a l l y s i g n i f i c a n t i n f l u e n c e on the t r a i t s under study. Herd e f f e c t s were expected t o be s i g n i f i c a n t f o r a l l t r a i t s . Seasonal e f f e c t s , estimated by sampling i n summer and winter seasons, were c o n s i d e r e d as p o t e n t i a l l y important. An i n t e r a c t i o n between herds and seasons was deemed important and i n c l u d e d i n adjustments f o r a l l t r a i t s . The c o v a r i a b l e s used i n the analyses were unique t o the serum and production t r a i t s . Age at l a c t a t i o n s t a r t and stage o f l a c t a t i o n at time of b l e e d i n g were the c o v a r i a b l e s a p p r o p r i a t e f o r serum t r a i t s , while age a t l a c t a t i o n s t a r t and le n g t h of l a c t a t i o n were a p p r o p r i a t e i i i c c v a r i a b l e s f o r t h e p r o d u c t i o n t r a i t s . A l l e f f e c t s were e v a l u a t e d by l e a s t s q u a r e s t e c h n i q u e s . The t r a i t s u n d e r s t u d y w e re a d j u s t e d by t h e l e a s t s q u a r e s c o n s t a n t s w i t h t h e r e s u l t i n g c o r r e c t e d d a t a s u b j e c t e d t o t h e g e n e t i c a n a l y s i s . The t r a i t s t h a t were d i s c e r n e d t o have a s i g n i f i c a n t h e r i t a b i l i t y i n c l u d e d a l l t h e p r o d u c t i o n t r a i t s a n d t h e f o l l o w i n g serum c o n s t i t u e n t s : c r e a t i n i n e ( 0 . 3 2 ) , a l k a l i n e p h o s p h a t a s e {0.30), a m y l a s e (0,20), p o t a s s i u m {0.13), and a l b u m i n {0.08). SGOT and EUN were a l s o deemed o f i n t e r e s t w i t h h e r i n a b i l i t i e s o f 0.05 and 0.05, r e s p e c t i v e l y . G e n e t i c c o r r e l a t i o n s t h a t e x i s t e d among t h e t r a i t s were a l s o e v a l u a t e d . The e v a l u a t i o n o f t h e s e c o r r e l a t i o n s was c a r r i e d o u t i n l i g h t o f t h e m a g n i t u d e o f t h e c o r r e l a t i o n a n d t h e r e l a t i v e m a g n i t u d e o f 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 . The g e n e t i c c o r r e l a t i o n s j u d g e d r e l i a b l e w e r e a s f e l l o w s : c r e a t i n i n e c o r r e l a t e d h i g h l y a n d n e g a t i v e l y w i t h b o t h m i l k f a t and m i l k p r o t e i n f o r b o t h f i r s t and c u r r e n t l a c t a t i o n s . A l k a l i n e p h o s p h a t a s e c o r r e l a t e d h i g h l y a n d n e g a t i v e l y w i t h a l l p r o d u c t i o n t r a i t s f o r b o t h l a c t a t i o n s . P o t a s s i u m and a l b u m i n e x h i b i t e d r e l i a b l e , p o s i t i v e c o r r e l a t i o n s w i t h m i l k p r o d u c t i o n a l o n e . G e n e t i c c o r r e l a t i o n s were a l s o e x a m i n e d among se r u m t r a i t s i n o r d e r t o e l u c i d a t e common u n d e r l y i n g g e n o t y p e s . SGOT e x h i b i t e d a p o s i t i v e c o r r e l a t i o n w i t h a m y l a s e , p o t a s s i u * a n d a l b u m i n , and a n e g a t i v e c o r r e l a t i o n w i t h a l k a l i n e p h o s p h a t a s e . BON was n e g a t i v e l y c o r r e l a t e d w i t h a m y l a s e a n d p o s i t i v e l y c o r r e l a t e d with albumin. C r e a t i n i n e was c o r r e l a t e d p o s i t i v e l y with a l k a l i n e phosphatase, and amylase, a l k a l i n e phosphatase c o r r e l a t e d n e g a t i v e l y with amylase and potassium. Potassium was p o s i t i v e l y c o r r e l a t e d with albumin. T h i s study estimated and t a b u l a t e d the g e n e t i c parameters i n v o l v i n g some serum and production t r a i t s i n d a i r y c a t t l e , f u r t h e r , i t reduced the t o t a l number of serum c o n s t i t u e n t s to a subset which demonstrated a g e n e t i c component or a g e n e t i c involvement i n other t r a i t s . , TABLE OF CONTENTS Ab s t r a c t *. v . . . . . . . . . . . ........«..ii L i s t of Tables . . . . . . . . . . •.-.......»......... .....v.. v i Acknowledgements ...,;............ •. .... •........ ...... . . v i i I n t r o d u c t i o n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v . . 1 L i t e r a t u r e Review 5 H a t e r i a l s and Hethods 19 Lata C o l l e c t i o n and A n a l y s i s 19 S t a t i s t i c a l Models . . . . . . . . . . . . . . . . . . . . . . , 2 7 E s t i m a t i o n o f Variance Components 29 Variance o f Variance Components .... 31 H e r i t a b i l i t y Estimates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Variance of H e r i t a b i l i t y Estimates . . . . . . . . . . . . . . . . . . 3 3 C o r r e l a t i o n Estimates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Variance of C o r r e l a t i o n E s t i m a t e s . . . . « . . • • • . . . * . . . . . 34 R e s u l t s and D i s c u s s i o n 35 C o n c l u s i o n . . . . . . . . v . . . . . . . • • . . . • • . . . . . . . . . . . . . . 7 5 B i b l i o g r a p h y ................... ...... ......v. 79 Appendix .................. ...... • ...»••• ..»........•..• 8 LIST OF TABLES Tabl e I A n a l y s i s of va r i a n c e (ANOV) t a b l e and expected mean squares (EMS) f o r the experimental models. Table I I Least sguares constants a s s o c i a t e d with summer and winter seasons and with the c o v a r i a b l e s . Table I I I L e a s t squares means and a s s o c i a t e d standard e r r o r s (SE) with R 2 f o r a l l c o r r e c t i o n terms. Table IV Variance components and h e r i t a b i l i t i e s with a s s o c i a t e d SE f o r the i n d i v i d u a l t r a i t s . T a ble V Phenotypic {below diagonal) and environmental (above diagonal) c o r r e l a t i o n s among t r a i t s with a s s o c i a t e d SE. , Table VI G e n e t i c c o r r e l a t i o n s {below diagonal) and g e n e t i c components of c o v a r i a n c e (above diagonal) with a s s o c i a t e d SE. Table VII Genetic (above) and phenotypic (below) c o r r e l a t i o n s between s e l e c t e d serum c o n s t i t u e n t s and the production t r a i t s . , Table VIII G e n e t i c (above diagonal) and phenotypic (below diagonal) c o r r e l a t i o n s among s e l e c t e d serum c o n s i t i t u e n t s . v i i ACKNOWLEDGEMENTS The author would l i k e to take t h i s o p p o r t u n i t y to acknowledge the e f f o r t s o f those people who were of prime importance i n the r e s e a r c h and p r e p a r a t i o n of t h i s t h e s i s . Many thanks t o Dr. E . G . Peterson f o r h i s help i n i n i t i a t i n g the study and h i s d i s c u s s i o n during the r e s e a r c h and t h e s i s p r e p a r a t i o n , a l l o f which proved i n v a l u a b l e . To Mabel S t r i k e r and Duncan J e f f r i e s , many thanks f o r the t e c h n i c a l a s s i s t a n c e with the computer work r e g u i r e d i n t h i s study, and a g a i n , f o r s t i m u l a t i n g d i s c u s s i o n which helped i n the w r i t i n g of t h i s manuscript. F i n a l l y , many thanks t o my w i f e , P a t r i c i a , f o r encouragement and help i n the p h y s i c a l p r e p a r a t i o n of t h i s document. 1 IMJOEUCTION The s e l e c t i o n of d a i r y c a t t l e f o r the p r o d u c t i o n of s i l k , milk f a t and milk p r o t e i n has r e c e i v e d much a t t e n t i o n i n recent h i s t o r y . S e l e c t i o n has been i n t e n s e and r e s e a r c h e r s have r e f i n e d s e l e c t i o n models and techniques t o such a degree that c o n v e n t i o n a l s e l e c t i o n procedures are not l i k e l y t o produce the dramatic improvements achieved i n the past (Bobertson 1966). In order t h a t progress c o n t i n u e , r e s e a r c h e r s must e x p l o r e areas which e x p l o i t the r e s t r i c t i o n s present i n the br e e d i n g of d a i r y c a t t l e . These r e s t r i c t i o n s i n c l u d e the s e x - l i m i t e d nature of the t r a i t s , the c o s t of r a i s i n g replacement females to an age where the t r a i t s are measureable, and t h e i n i t i a l s e l e c t i c n and c o s t of r a i s i n g replacement males. These f a c t o r s e f f e c t i v e l y l i m i t the number o f animals t e s t e d and i n c r e a s e the genera t i o n i n t e r v a l , thus l i m i t i n g s e l e c t i o n response per u n i t time. I f s e l e c t i o n procedures c o u l d overcome these r e s t r i c t i o n s , i t would r e p r e s e n t an improvement i n g e n e t i c and economic terms. S e l e c t i o n f o r t r a i t s t h a t are c o r r e l a t e d with the milk production t r a i t s and are a v a i l a b l e e a r l y i n l i f e r e p r e s e n t s one method of overcoming these r e s t r i c t i o n s . T r a i t s measurable i n the blood are among the more promising i n t h i s r e p e c t . Bleed i s the i n t e r m e d i a r y f l u i d between the mammary system and the r e s t of the animal. As such, i t c o n t a i n s i n p u t compounds t o the milk s y n t h e s i s process as w e l l as some compounds s u p e r f l u o u s to the process. In a d d i t i o n , blood c o n t a i n s other compounds which are 2 i n d i c a t i v e of g e n e r a l body c o n d i t i o n or o f the animal's g e n e t i c makeup. The l a t t e r has been s t u d i e d by examining the r e l a t i o n s h i p s between v a r i o u s polymorphic t r a i t s and milk production t r a i t s . Some polymorphic systems s t u d i e d were red blood c e l l antibody r e a c t i o n , serum t r a n s f e r r i n , and enzyme types. P i r c h n e r (1969) reviewed these r e l a t i o n s h i p s and noted the s t r o n g e s t r e l a t i o n s h i p s e x i s t e d between c e r t a i n blood type a l l e l e s and milk f a t percentage, yet these r e l a t i o n s h i p s accounted f o r l e s s than t e n percent of the g e n e t i c v a r i a n c e of milk f a t percentage. Other polymorphic systems have not proven t o be h i g h l y c o r r e l a t e d with milk production. In a d d i t i o n to t h i s f a i l i n g , t h e r e are other i n t r i n s i c d i f f i c u l t i e s a s s o c i a t e d with polymorphic systems. By d e f i n i t i o n , they are systems t h a t are composed of a s m a l l number of a l l e l e s a t one or a few l o c i . Assuming gene a c t i o n to be a d d i t i v e , s e l e c t i o n would cause a trend towards homozygosity i n a few g e n e r a t i o n s a t the l o c i i n v o l v e d . . The attainment o f homozygosity w i l l r e s u l t i n no f u r t h e r response to s e l e c t i o n . •• A l s o , due to the p l e i o t r o p y of gene e f f e c t , homozygosity may r e s u l t i n a decrease i n performance i n other t r a i t s , f o r example, f i t n e s s and r e p r o d u c t i v e performance. There are d i s c r e p a n c i e s i n the s t a t i s t i c a l and b i o l o g i c a l i n t e r p r e t a t i o n o f c o r r e l a t i n g a system of f i n i t e c l a s s i f i c a t i o n (polymorphism) with a t r a i t t h a t i s c o n t i n u o u s l y v a r i a b l e (the milk production t r a i t s ) . . I f the polymorphic system does have an input i n t o the c o n t i n u o u s l y 3 v a r i a b l e t r a i t , i t must be s m a l l i n r e l a t i o n t o t h e f a c t o r s w h i c h g i v e t h e t r a i t i t s c o n t i n u o u s d i s t r i b u t i o n . T h e s e o t h e r f a c t o r s c o u l d be s y s t e m a t i c o r e n v i r o n m e n t a l i n n a t u r e . The s y s t e m a t i c f a c t o r s o f f e r a n a r e a f o r f a r t h e r s t u d y . T h i s p r e s e n t s t u d y u s e d t r a i t s t h a t were c o n s i d e r e d t o be c o n t i n u o u s i n t h e i r d i s t r i b u t i o n a n d n o t b a s e d p r i m a r i l y o n a p o l y m o r p h i c s y s t e m . T h e r e a r e many compounds i n t h e b l o o d t h a t a r e c o n t i n u o u s l y v a r i a b l e a n d r e l e v a n t t o m i l k s y n t h e s i s . T hese compounds c a n be r o u g h l y g r o u p e d i n t o t h o s e f o r m i n g a m a t e r i a l p o r t i o n o f m i l k , t h o s e e x t r a c t e d by t h e mammary c e l l s a n d s y n t h e s i z e d i n t o m i l k c o m p o n e n t s , and t h o s e w h i c h do n o t f o r m a m a t e r i a l p a r t o f m i l k b u t w h i c h m e d i a t e some o f t h e b i o c h e m i c a l p a t h w a y s i n v o l v e d i n m i l k s y n t h e s i s . B e s i d e s t h e c o n s t r a i n t s o f r e l e v a n c e t o m i l k s y n t h e s i s , t h e r e a r e o t h e r c o n s i d e r a t i o n s when s e l e c t i n g w h i c h b l o o d c o n s t i t u e n t s t o m e a s u r e . E a s e a n d c o s t o f m e a s u r e m e n t must be c o n s i d e r e d i f i t i s i n t e n d e d t o a p p l y t h e r e s u l t s i n a f i e l d s t u d y a p p r o a c h . C e r t a i n c o n s t i t u e n t s may a p p e a r more p r e m i s i n g i n t h e i r r e l a t i o n s h i p w i t h p r o d u c t i o n t r a i t s , y e t c o s t o f measurement may be p r o h i b i t i v e when a p p l i e d t o a l a r g e number o f a n i m a l s . F o r t h i s r e a s o n , t h i s p r e s e n t s t u d y was b a s e d l a r g e l y on a human b i o m e d i c a l p r o f i l e w h i c h p r o v i d e d an e f f i c i e n t s u r v e y o f b l o o d c o n s t i t u e n t s t h a t were i n d i c a t i v e o f a w i d e r a n g e o f b o d y f u n c t i o n s . To t h i s p r o f i l e w e r e added s e v e r a l c o n s t i t u e n t s 4 which were judged to be of p a r t i c u l a r r e l e v a n c e to milk production or r e p r o d u c t i v e performance and which had s a t i s f a c t o r y a n a l y t i c a l techniques a v a i l a b l e . I f one i s to u t i l i z e a t r a i t i n c o n v e n t i o n a l s e l e c t i o n t h e o r y , c e r t a i n g e n e t i c parameters must be known. H e r i t a b i l i t i e s and g e n e t i c v a r i a n c e s must be r e l i a b l y estimated f o r those t r a i t s t o be used i n d i v i d u a l l y . I f one d e s i r e s to use a number of t r a i t s s i m u l t a n e o u s l y , or i f one d e s i r e s to r e l a t e the change i n p r o d u c t i o n t r a i t s concurrent with changes i n blood c o n s t i t u e n t s , g e n e t i c and phenotypic c o r r e l a t i o n s between these t r a i t s must a l s o be estimated. In t h i s present study, estimates of a l l the above mentioned g e n e t i c parameters w i l l be estimated and evaluated i n an attempt to present a more complete and comprehensive i n v e s t i g a t i o n . I t i s proposed t h a t some important r e l a t i o n s h i p s between the production t r a i t s and some subset of the serum c o n s t i t u e n t s measured can be a s c e r t a i n e d . 5 LITESATOBE BEVIBB In a p a r t i c u l a r study one i s u s u a l l y i n t e r e s t e d i n one or a few major e f f e c t s . The experiment i s s e t up and c a r r i e d out i n order t o f a c i l i t a t e the a n a l y s i s of these e f f e c t s . In g e n e r a l , there a re other f a c t o r s which are s i g n i f i c a n t but not of prime importance, , These secondary e f f e c t s must a l s o be q u a n t i f i e d as a c c u r a t e l y as p o s s i b l e and taken i n t o account i n the a n a l y s i s . In t h i s p a r t i c u l a r study, the main i n t e r e s t was i n a s i r e e f f e c t so that h e r i t a b i l i t i e s and c o r r e l a t i o n s c o u l d be d e r i v e d and t e s t e d s t a t i s t i c a l l y , , Beyond the s i r e e f f e c t * many r e a d i l y i d e n t i f i a b l e f a c t o r s a f f e c t blood composition. I f they can be q u a n t i f i e d and i n t e r p r e t e d , they deserve a p l a c e i n the a n a l y s i s . I t i s optimal t o i d e n t i f y and remove as many s i g n i f i c a n t e f f e c t s as p o s s i b l e , i n order t o get a complete understanding o f the nature o f the blood c o n s t i t u e n t s . Age has been c i t e d as a f a c t o r i n governing l e v e l s of serum c o n s t i t u e n t s by many r e s e a r c h e r s . Age may be due to a number of processes t h a t appear or change as the animal matures. Within the range present i n t h i s study, age may not be as important s i n c e the animals were a more homogeneous group than expected under random c o n d i t i o n s . A l l animals sampled i n t h i s study were l a c t a t i n g and t h e r e f o r e the age range of 0-23 months was not rep r e s e n t e d . , The a c t u a l age range i n t h i s study was 23 months to 157 months, with a c o n c e n t r a t i o n i n the lower p o r t i o n o f t h i s 6 range. There s t i l l was p r e s e n t , however, the e f f e c t s of continued growth, the maturing processes and age r e l a t e d s t r e s s e s . Serum c a l c i u m l e v e l s have been r e p o r t e d to be s i g n i f i c a n t l y a f f e c t e d by age., Tumbleson et a l . {1973b) repo r t e d a s i g n i f i c a n t l i n e a r decrease i n c a l c i u m l e v e l with age. No s i g n i f i c a n t age e f f e c t was r e p o r t e d by Kitchenham e t a l . (1975) and Kitchenham and Rowlands (1S76). T h i s c o n c l u s i o n was based on values obtained over a number of herds. I n o r g a n i c phosphate has been noted t o decrease with age. Tumbleson e t a l . (1973b) r e p o r t e d 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 , while Kitchenham et a l . (1975) and Kitchenhas and Rowlands (1976) termed i t a s i g n i f i c a n t l i n e a r r e l a t i o n s h i p . Sodium, potassium and c h l o r i n e were not reported t o be a f f e c t e d by age, over the range i n the present study (Tumbleson et a l . 1S73b and Kitchenham e t aJL. 197 5). Blood urea n i t r o g e n (BON) f o l l o w e d a s i m i l a r p a t t e r n , t h a t i s , s i g n i f i c a n t l y a f f e c t e d by age up to two years but s t a b i l i z i n g a f t e r t h at p o i n t (Tumbleson e t a l , 1973b and Kitchenham et a l . 1975). The study by Kitchenham and Rowlands (1976) i n d i c a t e d a s i g n i f i c a n t decrease i n sodium and urea with age, although the range s t u d i e d was 1.25 t o 12.75 years. T h i s range was wider than our experimental range. S i n c e most of the s i g n i f i c a n c e appeared i n the 0 - 24 months of age range, the reduced lower l i m i t may account f o r the s i g n i f i c a n c e noted i n t h i s study. Furthermore, Kitchenham and Rowlands (1976) noted 7 t h a t the decrease of sodium with age may have been s p e c i f i c t o the herd under study. Serum p r o t e i n s have been noted t o be a f f e c t e d by age. Tumbleson e t a l . (1973a) s t a t e d t h a t t o t a l p r o t e i n i n c r e a s e d with age while a l k a l i n e phosphatase decreased with age. albumin showed no r e l a t i o n s h i p with age./ L i t t l e (1974) noted an i n c r e a s e of albumin frcm two through f o u r years o f age but no s i g n i f i c a n t r e l a t i o n s h i p t h e r e a f t e r . L i p i d compounds measured i n the present, study were c h o l e s t e r o l and t r i g l y c e r i d e s . Arave et a l . (1S75) i n d i c a t e d an i n c r e a s e i n c h o l e s t e r o l c o n c e n t r a t i o n with age but again the range d i f f e r e d frcm t h a t used i n the present study. T o t a l l i p i d s were p o s i t i v e l y c o r r e l a t e d with c h o l e s t e r o l (r=0.71). T r i g l y c e r i d e s make up a l a r g e p o r t i o n of t o t a l serum l i p i d s and i t may be expected t h a t t r i g l y c e r i d e s l e v e l s are a l s o a f f e c t e d by age, Tumbleson and Hutcheson (1971) f u r t h e r c l a r i f i e d the s i t u a t i o n by s t a t i n g c h o l e s t e r o l l e v e l s i n c r e a s e d up to t h r e e years of age and decreased t h e r e a f t e r , , This decrease a f t e r t hree years o f age was s p e c u l a t e d t o have been caused by s e l e c t i v e c u l l i n g of c i d e r animals. B i l i r u b i n was noted by Tumbleson and Hutcheson (1971) to s i g n i f i c a n t l y i n c r e a s e with age, Mylrea and Healy 41968) concurred with t h i s statement. Thyroxine s e c r e t i o n r a t e d e c l i n e d with i n c r e a s i n g age over the normal productive age range i n d a i r y goats (Flamboe and fieineke 1959). 8 Kitchenham et a l . (1975) noted an i n c r e a s e i n serum glucose with age i n a study i n v o l v i n g a number of herds. Kitchenham and Rowlands (1976), i n a w i t h i n herd study, r e p o r t e d no r e l a t i o n s h i p between glucose and age. F u r t h e r o b s c u r i n g t h i s s i t u a t i o n was a r e p o r t by Tumbleson and Hutcheson (1971). T h i s was a w i t h i n herd study which showed a s i g n i f i c a n t r e l a t i o n s h i p from 0.5 to 5 years o f age, with no change t h e r e a f t e r . The range of s i g n i f i c a n c e encompasses most of the present study»s data, although the lower age l i m i t was again much lower. Peterson and Haldern (1978) rep o r t e d s i g n i f i c a n t decreases with age i n the l e v e l of i n o r g a n i c phosphorus, BON, c h o l e s t e r o l , a l k a l i n e phosphatase, serum glutamic o x a l o a c e t i c transaminase (SGOT) and albumin, and s i g n i f i c a n t i n c r e a s e s i n t o t a l p r o t e i n and g l u c o s e . These were i n c l o s e agreement with Kitchenham et a l . (1975) and Tumbleson e t a l . (1973a) and (1973b)., Seasonal e f f e c t s were c o n s i d e r e d p o t e n t i a l l y important f o r the p o p u l a t i o n s t u d i e d . Blood samples were taken i n both summer and winter, and the d i f f e r e n c e i n sampling p e r i o d was taken as a measure of the seasonal e f f e c t s . These e f f e c t s may have i n c l u d e d d i f f e r e n c e s i n c l i m a t e , d i e t and fee d i n g management as major c a u s a l f a c t o r s , R e l a t i v e l y few of the c o n s t i t u e n t s present i n blood serum have been shown to vary s e a s o n a l l y . Sodium was noted to be s i g n i f i c a n t l y lower i n summer than winter, while urea and 9 albumin c o n c e n t r a t i o n s were hig h e r i n s'usier (Payne et a l . 1974). Boss and H a l l i d a y (1976) di s p u t e d t h i s r e l a t i o n s h i p f o r albumin, and f u r t h e r s t a t e d t h a t c a l c i u m was s i g n i f i c a n t l y higher i n the summer. Drea was found (Payne e t a l , 1974) to be higher i n summer. T h i s may be due t o i n c r e a s e d p r o t e i n i n t a k e i n grass i n the summer. Increased d i e t a r y p r o t e i n has been shown by some s t u d i e s ( L i t t l e and flanston 1972, Manston et a l . 1S75, P r e w i t t e t a l . 1971) to a f f e c t BUN. T h i s e f f e c t should be lessened when herds have a c o n s i s t e n t f e e d i n g program throughout the year. Boss and H a l l i d a y (1976) noted higher summer l e v e l s of serum c h o l e s t e r o l , although t h i s was i n g e n e r a l c o n f l i c t with Arave e t a l . (1975) who noted g e n e r a l l y lowered c h o l e s t e r o l l e v e l s i n summer. Neither study provided strong b a s i s f o r the argument of s i g n i f i c a n t seasonal e f f e c t . I n f o r m a t i o n on sea s o n a l e f f e c t s f o r SGOT and a l k a l i n e phosphatase was a l s o l i m i t e d . In a summer^winter system of b l e e d i n g , Boussel and S t a l l c u p (1966) noted a s i g n i f i c a n t s easonal d i f f e r e n c e f o r both enzymes. The importance of t h i s r e s u l t was tempered by the f a c t t h a t t h e range of age f o r the aniffials (0-2 years) i n t h i s study was not the same as i n the present study, and by the statement made by Boussel and S t a l l c u p (1966) t h a t , age d i f f e r e n c e s i n t h e i r study c o u l d not be completely separated from s e a s o n a l e f f e c t s . Two papers (Flamboe and Beineke 1959, Hixner et a l , 1962) i n d i c a t e d s i g n i f i c a n t s easonal e f f e c t s with regards to t h y r o x i n e 10 l e v e l i n the blood. , Herd e f f e c t s were noted t o account f o r t h e l a r g e s t s i n g l e p o r t i o n of the v a r i a b l i t y a s s o c i a t e d with many blood c o n s t i t u e n t s (Hewett 1974, Payne e t a l . 1974, Rowlands and Hanston 1976}. T h i s was c o n s i s t e n t with the o b s e r v a t i o n that herd d i f f e r e n c e s are comprised of a number of s m a l l e r e f f e c t s , notably f e e d i n g , management and the microenvironment a s s o c i a t e d with the farm. V i r t u a l l y a l l blood c o n s t i t u e n t s i n v o l v e d i n the present study have been r e p o r t e d i n the l i t e r a t u r e to be s i g n i f i c a n t l y a f f e c t e d by herd. Payne et a l . (1973) and (1974) i n two s t u d i e s i n d i c a t e d t h a t a l l c o n s t i t u e n t s i n v o l v e d i n t h e Ccmpton Metabolic P r o f i l e (CMP) were s i g n i f i c a n t l y a f f e c t e d by herd. Hewett (1974) concurred with these r e s u l t s . The c o n s t i t u e n t s common to the Ccmpton s t u d i e s and the present study were glucose, BON, i n o r g a n i c phosphate, calcium, sodium, potassium and albumin, Wilson and D i n k e l (1968) a r r i v e d at the same c o n c l u s i o n r e g a r d i n g t h e importance of herd e f f e c t . S p e c i f i c a l l y , they noted the s i g n i f i c a n c e of herd on the v a r i a b i l i t y of c r e a t i n i n e and a l k a l i n e phosphatase. The herd e f f e c t on u r i c a c i d , c h o l e s t e r o l , t o t a l p r o t e i n , b i l i r u b i n , SGOT, t r i g l y c e r i d e s , c h l o r i n e , b i c a r b o n a t e , t h y r o x i n e and amylase was not w e l l r e p o r t e d i n the l i t e r a t u r e . From the l i t e r a t u r e reviewed, i t was expected herds would be important c o n t r i b u t o r s t o the v a r i a t i o n i n most of the parameters 11 measured. Moreover, some s t a t i s t i c a l c o m p l i c a t i o n s may a r i s e due t o i n t e r a c t i o n s between herds and other s ources of v a r i a t i o n . Payne e t a l . (1974) i n d i c a t e d t h a t the herd by l a c t a t i o n a l group i n t e r a c t i o n was l a r g e i n comparison to l a c t a t i o n a l group e f f e c t . Since the stage of l a c t a t i o n at time of sampling i s a s s o c i a t e d with d i f f e r e n t production s t r e s s e s and n u t r i t i o n a l regimes, i t should be taken i n t o account as a source of v a r i a t i o n i n blood c o n s t i t u e n t l e v e l s . , Many s t u d i e s i n the l i t e r a t u r e i n c l u d e d some measure of l a c t a t i o n stage i n t h e i r a n a l y s i s . In one of the Compton s t u d i e s , Bowlands e t aj.. {1975) noted the general s i t u a t i o n of s i g n i f i c a n t v a r i a b i l i t y i n c o n s t i t u e n t l e v e l s due to stage o f l a c t a t i o n i n the range of 0-120 days, with l i t t l e e f f e c t beyond t h i s range. Exceptions to t h i s general s i t u a t i o n were i n o r g a n i c phosphate and potassium, both of which showed no s i g n i f i c a n t t r e n d with regards t o stage of l a c t a t i o n . More s p e c i f i c a l l y , the r e s u l t s of lowlands et a l . (1975) i n d i c a t e d t h e f o l l o w i n g : g l u c o s e j BON, t o t a l p r o t e i n and c a l c i u m were lowest at the s t a r t o f l a c t a t i o n and showed a s i g n i f i c a n t i n c r e a s e t h e r e a f t e r . Sodium decreased as l a c t a t i o n progressed. Albumin showed the s t r o n g e s t r e l a t i o n s h i p with l a c t a t i o n , e s p e c i a l l y i n the e a r l y s t a g es. L i t t l e {1974) concurred with t h i s p o s i t i v e r e l a t i o n s h i p . . / Hewett (1974) a l s o looked at e f f e c t o f l a c t a t i o n on an extended blood p r o f i l e , u s i ng monthly groups as stages of l a c t a t i o n . , He noted i n o r g a n i c 12 phosphate and potassium were not a f f e c t e d by l a c t a t i o n , and t h a t sodium, t o t a l p r o t e i n and BUN were s i g n i f i c a n t l y a f f e c t e d . These r e s u l t s were i n agreement «ith Rowlands e t a l . (1975). On the other hand, Hewett (1974) r e p o r t e d glucose, c a l c i u i and albumin were not s i g n i f i c a n t l y a f f e c t e d by l a c t a t i o n . I t should be pointed out t h a t Hewett (1974) was c o n s i d e r i n g a much l a r g e r range o f l a c t a t i o n stage i n h i s s t u d i e s . Hewett (1974) a l s o noted t h a t there was no s i g n i f i c a n t e f f e c t of stage of l a c t a t i o n on any of t h r e e measures of t h r y o i d a c t i v i t y , namely p r o t e i n bound i o d i n e , t o t a l i o d i n e and i n o r g a n i c i o d i n e . Mixner e t a l . (1962) noted a s i g n i f i c a n t e f f e c t on t h y r o i d s e c r e t i o n as measured by the chemical t h y r o x i n e turnover method. The e f f e c t of an animal's genotype on the v a r i a b i l i t y of blood c o n s t i t u e n t l e v e l i s of prime importance i n the present study. Body me t a b o l i t e s and b i o l o g i c a l compounds present i n body f l u i d s are the r e s u l t of s y n t h e s i s of n u t r i e n t s absorbed from the gut, and or a r i s e as by-products of b o d i l y f u n c t i o n s . I t i s g e n e r a l l y accepted t h a t many of these processes are under g e n e t i c c o n t r o l , e i t h e r d i r e c t l y , as i n p r o t e i n s y n t h e s i s , or i n d i r e c t l y through c o n t r o l of enzyme p r o d u c t i o n . Whether t h i s g e n e t i c c o n t r o l was a s s o c i a t e d with a p o r t i o n of the observed v a r i a b i l i t y i n blood c o n s t i t u e n t l e v e l was under q u e s t i o n and has r e c e i v e d some a t t e n t i o n i n the l i t e r a t u r e . S tudies i n v o l v i n g the CHP repo r t e d a s i g n i f i c a n t 13 h e r i t a b i l x t y f o r many of the c o n s t i t u e n t s t e s t e d . Osing h a l f s i b c o r r e l a t i o n s , Kithchenham and fiowlands (1976) r e p o r t e d s i g n i f i c a n t h e r i t a b i l i t i e s ( tstandard e r r o r ) f o r BUN (0.77±0.38) , albumin (0.47±0.33) , t o t a l p r o t e i n (0.50*0.34), c a l c i u m (0.46±0,33) and potassium (0.53±0.34). Sodium, glucose and i n o r g a n i c phosphorus were a s s o c i a t e d with i n s i g n i f i c a n t h e r i t a b i l i t i e s . The standard e r r o r s a s s o c i a t e d with these h e r i t a b i l i t i e s were q u i t e l a r g e , due mainly to the experimental design which r e s u l t e d i n s m a l l progeny groups of approximately f o u r animals each. Bobertson (1959) s t a t e d t h a t s m a l l progeny group s i z e w i l l r e s u l t i n high standard e r r o r s and thus u n r e l i a b l e e s t i m a t e s . Dam-daughter r e g r e s s i o n s i n the same study by Kitchenham and Rowlands (1976) showed reduced h e r i t a b i l i t y estimates with more r e l i a b l e standard e r r o r s . However, these e s t i m a t e s were s i g n i f i c a n t only f o r t o t a l p r o t e i n . An e a r l i e r study by Bowlands e t a l . (1974) estimated h e r i t a b i l i t i e s f o r a number of c o n s t i t u e n t s using h a l f s i b a n a l y s i s on beef c a l v e s o f 9-11 weeks of a<?e, A f t e r e l i m i n a t i n g d i f f e r e n c e s a s s o c i a t e d with the two r e g i o n s i n v o l v e d i n the study, s i g n i f i c a n t h e r i t a b i l i t i e s were estimated f o r glucose (0.18±0.16), potassium (0.40±0.23), calcium (0.19±0.17), albumin (0. 10±0.13) and i n o r g a n i c phosphate (0.18±0.16). N e n s i g n i f i c a n t h e r i t a b i l i t i e s were estimated f o r BON and sodium. T h i s was i n rough agreement with the former study, but two p o i n t s should be made. One i s that the second study d e a l t with animals o u t s i d e the range of age used i n t h i s present study. The other p o i n t i s 14 that the study i n v o l v i n g the beef c a l v e s was of such a design as to minimize the standard e r r o r s c f estimate and thus were more r e l i a b l e . Wilson and D i n k e l (1S68) reported on a s e t of c o n s t i t u e n t s which were l a r g e l y i n a d d i t i o n to those present i n the CMP, They noted i n s i g n i f i c a n t h e r i t a b i l i t i e s f o r i n o r g a n i c phosphate, c r e a t i n i n e and a l k a l i n e phosphatase, B e t t i n i e t a l . (1975) repor t e d h e r i t a b i l i t i e s for a l a r g e number of c o n s t i t u e n t s under examination i n the present study. They l i s t e d s i g n i f i c a n t h e r i t a b i l i t i e s f o r calcium (0.22), i n o r g a n i c phosphate (0.21), glucose (0.19), BON (0.10), u r i c a c i d (0.47), c h o l e s t e r o l (0.40), albumin (0.46)* b i l i r u b i n (0.12)* a l k a l i n e phosphatase (0.12) and SGOT (0.19). T h i s study used 213 cows i n e i g h t daughter groups, a design which should y i e l d r e l i a b l e esimates. Furtmayr (1975) estimated s i g n i f i c a n t h e r i t a b i l i t i e s f o r glucose (0,45), but r e p o r t e d i n s i g n i f i c a n t h e r i t a b i l i t i e s f o r b i l i r u b i n , c h o l e s t e r o l and SGOT, The g e n e t i c b a s i s of serum c h o l e s t e r o l l e v e l i s widely r e p o r t e d . Arave et a l , (1975) noted h a=0,50 f o r d a i r y c a t t l e i n t h e i r f i r s t l a c t a t i o n . Stufflebeam and L a s l e y (1969) and T a y l o r S i Jl« (1966) concurred with t h i s r e l a t i v e l y high h e r i t a b i l i t y . Some s t u d i e s have a t t a c k e d the problem of a g e n e t i c b a s i s of blood c o n s t i t u e n t l e v e l s by measuring the e f f e c t of breed. I f t h i s e f f e c t i s s i g n i f i c a n t , then i t may be reasonable t o p o s t u l a t e a g e n e t i c base and thus a h e r i t a b l e p o r t i o n of the v a r i a b i l i t y i n blood c o n s t i t u e n t l e v e l s . Heyns (1971a) noted 15 s i g n i f i c a n t breed d i f f e r e n c e s f o r a l k a l i n e phosphatase, potassium, c a l c i u m and glucose. N o n s i g n i f i c a n t breed d i f f e r e n c e s occurred f o r albumin, sodium, and i n o r g a n i c phosphate. Runkel et a l . (1953) noted s i g n i f i c a n t breed d i f f e r e n c e s f o r a l k a l i n e phosphatase although they noted f u r t h e r t h a t r e p e a t a b i l i t y w i t h i n breed i s low, i n d i c a t i n g environmental e f f e c t s overshadow breed e f f e c t s , Peterson and Waldern (1S78) have estimated r e p e a t a b l i l i t i e s f o r a group of serum c o n s t i t u e n t s b a s i c a l l y the same as the ones i n v o l v e d i n the present study. Since t h a t study was s e t up i n part to estimate r e p e a t a b i l i t i e s , the r e s u l t s were r e l i a b l e . The r e s u l t s of t h i s study were of i n t e r e s t i n s o f a r as r e p e a t a b i l i t y i s an upper l i m i t of h e r i t a b i l i t y . They r e p o r t e d moderate t o high r e p e a t a b i l i t i e s f o r i n o r g a n i c phosphate (0.194), c r e a t i n i n e (0.514), t o t a l p r o t e i n (0.613), a l k a l i n e phosphatase CO. 546), SGOT (0.264), glucose (0.205) and albumin (0.246) f o r animals i n l a c t a t i n g , nonpregnant c o n d i t i o n . The majority of cows i n the present study were i n t h i s c o n d i t o n . C o r r e l a t i o n s among l e v e l s of blood c o n s t i t u e n t s and between blood c o n s t i t u e n t s and p r o d u c t i o n t r a i t s could be of great value i n s e l e c t i o n of breeding stock and p r e d i c t i o n of f u t u r e performance. The Compton r e s e a r c h e r s have noted some c o r r e l a t i o n s among the c o n s t i t u e n t s they have s t u d i e d . Kitchenham and Bowlands (1976), using c o r r e l a t i o n s a d j u s t e d f o r age and breed, noted a s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n between 16 c a l c i u m and albumin (r=0.33). Payne e t a l . (1974), u s i n g simple c o r r e l a t i o n c o e f f i c i e n t s , supported t h i s f i n d i n g , although i t was apparent only i n the summer p e r i o d . They f u r t h e r noted a s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n between i n o r g a n i c phosphate and potassium, with r=0.40 i n the winter season and r=0.24 i n the summer season. I n an e a r l i e r study, Payne e t a l . (1973) r e p o r t e d some s i g n i f i c a n t p a r t i a l c o r r e l a t i o n c o e f f i c i e n t s (BUS with i n o r g a n i c phosphate (0.49) and with albumin (0.42), i n o r g a n i c phosphate with potassium (0.25 to 0.60)), although t h e i r importance was l i m i t e d by the f a c t t h a t herd means were used i n the c a l c u l a t i o n s . Thus the w i t h i n herd v a r i a b i l i t y , which was judged t o be both l a r g e and e r r a t i c f o r these c o r r e l a t i o n s (Payne e t a l . 1973, Kitchenham e t a l . 1975), was not taken i n t o account., Rowlands et a l . (1974) l i s t e d s i g n i f i c a n t c o r r e l a t i o n s o f glucose with albumin (0.40), glucose with sodium (0.34), glucose with c a l c i u m (0.43), glucose with i n o r g a n i c phosphate (0.34), albumin with sodium (0.30), albumin with i n o r g a n i c phosphate (0.39), albumin with c a l c i u m (G.60), sodium with i n o r g a n i c phosphate (0.31) and sodium with c a l c i u m (0.31) . Heyns (1971b) r e p o r t e d c o r r e l a t i o n s among s e v e r a l c o n s t i t u e n t s i n v o l v e d i n the present study. S e v e r a l o f these were i n a d d i t i o n to those c o n s t i t u e n t s s t u d i e d by the Ccmpton group. A negative c o r r e l a t i o n between albumin and BUN (r=-0.180) was i n agreement with a study p r e v i o u s l y mentioned. Heyns a l s o presented s i g n i f i c a n t p o s i t i v e 17 c o r r e l a t i o n s of c r e a t i n i n e with BUN (0.212), albumin with phosphorus (0.397), glucose with a l k a l i n e phosphatase (0.290) and with phosphorus (0.192), and a l k a l i n e phosphatase with phosphorus (0.179). Negative c o r r e l a t i o n s were r e p o r t e d f o r glucose with BUN (-0.209) and with c r e a t i n i n e (-0.345). With regards to the e s t i m a t i o n o f c o r r e l a t i o n s between l e v e l s of blood c o n s t i t u e n t s , i t was apparent t h a t most of the s t u d i e s r e p o r t e d i n the l i t e r a t u r e were not set up p r i m a r i l y to d e a l with t h i s a spect. Instead, i n t e r e s t i n c o r r e l a t i o n s appeared t o be i n i t i a t e d a f t e r the c o l l e c t i o n of data i n order to expand the scope o f the study. To be most worthwhile, a study should be designed to estimate c o r r e l a t i o n s with a minimum of c o n s t r a i n t s . Furthermore, the design should allow s u b d i v i s i o n of t h i s phenotypic c o r r e l a t i o n i n t o both g e n e t i c and environmental components. C o r r e l a t i o n s between blood c o n s t i t u e n t s and milk production t r a i t s have r e c e i v e d seme a t t e n t i o n i n the l i t e r a t u r e . Payne S i a l . (1973), using the c r i t e r i o n t h a t an "abnormal" l e v e l of a serum c o n s t i t u e n t i s one which i s g r e a t e r than twe standard d e v i a t i o n s away frcm the p o p u l a t i o n mean, repo r t e d t h a t " d i s a p p o i n t i n g milk g u a l i t y and y i e l d " was a s s o c i a t e d with high l e v e l s of potassium or with lew l e v e l s of albumin, calcium or sodium. Of these i n d i c a t i o n s , the r e l a t i o n s h i p with lew l e v e l s of albumin was much the s t r o n g e s t . These were determined on a herd average b a s i s and thus d i s r e g a r d e d i n d i v i d u a l cow 18 d i f f e r e n c e s . Kitchenham et a l . , (1915) r e p o r t e d s i g n i f i c a n t p a r t i a l r e g r e s s i o n c o e f f i c i e n t s between milk y i e l d and glucose (b«=-0.082) , BON (b s=0. 033) and albumin (b» = 0. CC95), i n d i c a t i n g t h a t some degree of r e l a t i o n s h i p e x i s t s . Sink e t a l . (1973) l o o k e d at s e v e r a l i n t e r r e l a t i o n s h i p s between serum l i p i d s and production t r a i t s , but were unable t o r e p o r t any s i g n i f i c a n t c o r r e l a t i o n s between serum c h o l e s t e r o l and any milk production t r a i t . Two o t h e r s t u d i e s contained e x t e n s i v e l i s t s of c o r r e l a t i o n s between some serum c o n s t i t u e n t s and the milk production t r a i t s . Furtmayr (1975) , i n h i s Inaugural D i s s e r t a t i o n , r e p o r t e d on a study i n v o l v i n g 168 H o l s t e i n - F r i e s i a n s . His f i n d i n g s were t h a t milk y i e l d was p o s i t i v e l y c o r r e l a t e d with c h o l e s t e r o l (0,20) and with SGOT (0,33). A n e g a t i v e c o r r e l a t i o n e x i s t e d between glucose and milk y i e l d (-0.20), H i l k f a t percentage was p o s i t i v e l y c o r r e l a t e d with b i l i r u b i n (0.28) and n e g a t i v e l y c o r r e l a t e d with glucose (-0,27) and c h o l e s t e r o l (-0.25). Bondarenko et a l . (1976) i n d i c a t e d s i g n i f i c a n t , p o s i t i v e c o r r e l a t i o n s between milk f a t percentage and t r i g l y c e r i d e s , c h o l e s t e r o l and albumin. 19 l i l J i S IM MS. METHODS a) B a i l C o l l e c t i o n and A n a l y s i s : The animals sampled i n the present study were H c l s t e i n - F r i e s i a n d a i r y c a t t l e i n commercial d a i r y herds l o c a t e d i n the e a s t e r n F r a s e r V a l l e y r e g i o n of B r i t i s h Columbia. These 35 c o - o p e r a t i n g herds were chosen t o give as r e p r e s e n t a t i v e a sample as p o s s i b l e with regards to n u t r i t i o n , management technigues, microenvironments w i t h i n the area and a b i l i t y t o c o l l e c t production data from a recognized data c o l l e c t i o n scheme. S p e c i f i c a l l y the herds used had the f o l l o w i n g c h a r a c t e r i s t i c s . Herd s i z e ranged from 21 to 136 m i l k i n g cows with a guadrimodal d i s t r i b u t i o n of 40, 51, 56, and 59 cows per herd. Several management and f e e d i n g systems were used. Hany farms u t i l i z e d a p a s t u r i n g system i n the summer and most supplemented with s t o r e d f e e d s . S e v e r a l farms f e d conserved forages e x c l u s i v e l y throughout the year. Included i n the o v e r a l l c l a s s i f i c a t i o n cf s t o r e d feed were hay, corn s i l a g e , g rass s i l a g e and grass-legume s i l a g e and, on d i f f e r e n t farms many combinations of these feeds were used. Housing systems i n c l u d e d t r a d i t i o n a l s t a n c h i o n barns, l o o s e housing and f r e e s t a l l systems, with the l a t t e r being most numerous, a i l k i n g systems v a r i e d a c c o r d i n g l y . Bucket and p i p e l i n e m i l k i n g systems were found i n s t a n c h i o n barns, while v a r i o u s p a r l o u r systems were a s s o c i a t e d with loose and f r e e s t a l l housing, 20 Cow samplings w i t h i n each herd were c a r r i e d out i n order to f a c i l i t a t e the v a l i d e s t i m a t i o n of a l l sources of v a r i a t i o n t h a t were d i s c u s s e d i n the l i t e r a t u r e review. The methods and c o n s i d e r a t i o n s t h a t were employed i n t h e sampling w i t h i n herd f o l l o w . Age at l a c t a t i o n s t a r t was one c o n s i d e r a t i o n i n the sampling scheme. Sampling was concentrated on young, l a c t a t i n g a n i a a l s with r e l a t i v e l y few animals of advanced age. T h i s was done f o r a number of reasons. F i r s t l y , t h i s skewed d i s t r i b u t i o n was r e p r e s e n t a t i v e of the s t r u c t u r e of many herds, secondly, animals i n t h e i r f i r s t l a c t a t i o n would be l e s s h e a v i l y s e l e c t e d and l e s s s u b j e c t to s p e c i a l treatment than o l d e r animals t h a t were of known p r o d u c t i v e a b i l i t y . Thus, younger animals would y i e l d a sample i n keeping with the assumption of randomness. Stage o f l a c t a t i o n , measured as days from l a c t a t i o n s t a r t t o date of blood sampling, was a l s o a c o n s i d e r a t i o n . Samplings were c o n c e n t r a t e d i n the f i r s t 120 days of l a c t a t i o n to emphasize the peri o d of g r e a t e s t production s t r e s s . I f there were r e l a t i o n s h i p s between blood c o n s t i t u e n t s and production t r a i t s , i t c o u l d be expected t h a t these r e l a t i o n s h i p s w i l l become more pronounced i n p e r i o d s of s t r e s s o r marginal i n t a k e of n u t r i e n t s i n r e l a t i o n to requirements, Seasonal e f f e c t s were estimated by sampling each herd on 21 two separate o c c a s i o n s . The summer blood sampling was c a r r i e d out between J u l y 19 and 28, 1976, and the winter sampling was c a r r i e d out between January 19 and February 5, 1977. These two sampling seasons represented as much d i f f e r e n c e as p o s s i b l e i n c l i m a t e , n u t r i t i o n and management. They a l s o r e p r e s e n t e d p e r i o d s a t which the herds would have had adequate time to a d j u s t t o any s e a s o n a l changes. The same i n d i v i d u a l s were not sampled i n both seasons i n order t h a t the c o n s i d e r a t i o n s of the s t a t i s t i c a l design and i t s assumptions c o u l d be met. The s i r e component of v a r i a n c e was the s u b j e c t of prime i n t e r e s t i n t h i s study. The numbers o f animals sampled and the d i s t r i b u t i o n of t h i s sampling were a r r i v e d a t i n p a r t by c o n s i d e r i n g the r e l i a b i l i t y o f the estimates of the q e n e t i c parameters t h a t they would produce. Hobertscn (1959) s t a t e d t h a t when e s t i m a t i n g h e r i t a b i l i t i e s from s i b a n a l y s i s , s m a l l s i b group s i z e ( l e s s than 10 i n d i v i d u a l s per group) w i l l r e s u l t i n unacceptably high standard e r r o r s and thus u n r e l i a b l e estimates. The standard e r r o r of h e r i t a b i l i t i e s , a c c o r d i n g to Robertson (1959), are minimized when s i b groups are between 10 and 10 animals. On t h i s b a s i s , the present study was set op to s u b d i v i d e the animals sampled i n t o s i r e groups of d e s i r a b l e s i z e . The t o t a l number of animals sampled was 1030 of which 700 were analysed f o r the serum c o n s t i t u e n t s . H i t h i n the animals f o r which serum samples were an a l y s e d , 27 s i r e groups of 10 or more daughters c o u l d be a s c e r t a i n e d . The average s i r e group 22 s i z e was approximately 20 animals f o r a t o t a l of 545 animals with complete data. T h i s should r e s u l t i n r e l i a b l e e s t i m a t e s and acceptable standard e r r o r s , „ Blood was o b t a i n e d from the j u g u l a r v e i n and c o l l e c t e d i n v a c u t a i n e r tubes c o n t a i n i n g no a n t i c o a g u l a n t . These blood samples were allowed to c l o t and then were c e n t r i f u g e d w i t h i n 6 hours of c o l l e c t i o n , . Serum was p i p e t t e d and the e n t i r e sample f r o B one animal s p l i t i n t o f o u r subsamples of 2 ml or more. These subsamples were placed immediately i n t o a f r e e z e r and s t o r e d f o r approximately s i x months at -18° C u n t i l sent to a b i o m e d i c a l l a b o r a t o r y 1 f o r a n a l y s e s . The serum c o n s t i t u e n t s measured on a Technicon AutoAnalyzer SHA 12/60 were ca l c i u m (Ca) , i n o r g a n i c phosphate (P04) , glucose (Glue), SGOT, c h o l e s t e r o l ( C h o i ) , albumin (Alb) , BUN, u r i c a c i d , a l k a l i n e phosphatase (Alk P ) , b i l i r u b i n ( B i l i ) , and t o t a l p r o t e i n (T P), Other c o n s t i t u e n t s , which were measured on ether equipment, were sodium (Na), potassium (K), c r e a t i n i n e (Great), amylase (Amyl), t r i g l y c e r i d e s ( T r i g ) , c h l o r i d e ( C l ) , b i c a r b o n a t e (HC03), and the T4 f r a c t i o n of t h y r o x i n e . The c o n s t i t u e n t s present i n i c n form i n serum were c a l c i u m , sodium, potassium, c h l o r i d e and b i c a r b o n a t e . C a l c i u s was determined by a method modified from t h a t of K e s s l e r and Helfman *B. C. Biomedical L a b o r a t o r i e s , Burnaby, B. C. 23 (1964)./ T h i s m o d i f i c a t i o n v i r t u a l l y removed any i n t e r f e r e n c e from magnesium. The d e t e r m i n a t i o n was c o l o r i m e t r i c and u n i t s of measurement were l i l l i g r a m s per d e c i l i t r e (mg/dl). Sodium and potassium were determined hy s p e c t r o p h o t o l e t r i c methods using a Beckmann potassium, l i t h i u m , sodium flame with an i n t e r n a l l i t h i u m standard. U n i t s of measurement f o r both elements were m i l l i e g u i v a l e n t s per l i t r e (meg/1). C h l o r i d e and b i c a r b o n a t e were measured i n the serum by the method o u t l i n e d by Kenny and Cheng (1972). = B r i e f l y , t h i s was a simultaneous d e t e r m i n a t i o n with both c o n s t i t u e n t s being determined by c c l o r i m e t r y on a Beckmann c h l o r i d e carbon d i o x i d e a n a l y z e r . U n i t s of measurement were meg/1. P r o t e i n and compounds r e l a t e d t o p r o t e i n metabolism that were measured i n t h i s study were t o t a l p r o t e i n , albumin, BUS, u r i c a c i d , b i l i r u b i n and c r e a t i n i n e . T o t a l p r o t e i n was determined by a modified b i u r e t r e a c t i o n as d e s c r i b e d by Skeggs and Hochstrasser (1964). , Determination was c o l o r i m e t r i c and u n i t s were grams of t o t a l p r o t e i n per d e c i l i t r e ( g / d l ) 4 : Albumin was analysed by the method of Doumas e t al.. (1971) i n which a c o l o r i m e t r i c r e a c t i o n with bromcresol green was used. I t was noted t h i s technique was f r e e from i n t e r f e r e n c e with some other serum c o n s t i t u e n t s , most n o t a b l y b i l i r u b i n . U n i t s of measurement were g / d l . BUS determination u t i l i z e d the method re p o r t e d by Marsh et a l . . ( 1 9 6 5 ) . T h i s method e n t a i l e d the r e a c t i o n of urea with 24 diacetyl-monoxine i n the presence o f compounds t h a t enhance the c o l o r development. The advantage of t h i s method over e a r l i e r methods was i n i t s a b i l i t y to u t i l i z e r e a c t i o n s o f low a c i d i t y . Determination was c o l o r i m e t r i c and u n i t s were mg/dl. The method of a n a l y s i s o f u r i c a c i d was an automated v e r s i o n of the method s e t out by Sobrinho-SimeT>s (1965). I t was based on r e d u c t i o n of a phosphotungstate complex which r e s u l t e d i n s t a b l e c o l o u r development i n the presence of s t a b i l i z i n g and c o l o r i n t e n s i f y i n g agents. Determination was c o l o r i m e t r i c and u n i t s were mg/dl. y T o t a l b i l i r u b i n was estimated by the method of J e n d r a s s i k and Grof as adapted by Gambino and Sc h r e i b e r (1964)., Serum b i l i r u b i n was reac t e d with d i a z o t i z e d s u l f a n i l i c a c i d i n t h e presence o f a c a f f e i n e - s o d i u m benzoate reagent t o gi v e d i f f e r e n t i a l c o l o r i m e t r y between a sample and a blank r e a c t i o n , with u n i t s of mg/dl. C r e a t i n i n e was measured by t h e J a f f e Method which i n v o l v e d c c l c r i m e t r i c d e t e r m i n a t i o n of the r e a c t i o n ietween c r e a t i n i n e and a l k a l i n e p i c r a t e . U n i t s o f measurement were mg/dl., Enzymes measured i n t h e serum were SGOT, a l k a l i n e phosphatase and amylase. , SGOT was determined by the method of florganstern e t a l . (1966). O x a l o a c e t i c a c i d was generated from SGOT, d i a l y z e d and coupled with Fast Ponceau L, a diazcnium s a l t . T h i s method e l i m i n a t e d the need f o r running a concurrent c o n t r o l and c o r r e l a t e d w e l l with other d e t e r m i n a t i o n techniques. 25 T h i s was a c o l c r i m e t r i c measurement, with u n i t s of m i l l i l n t e r n a t i o n a l U n i t s per m i l l i l i t r e (mU/ml)• A l k a l i n e phosphatase was measured by use of e n z y s a t i c h y d r o l y s i s of p - n i t r o p h e n y l phosphate and subsequent c o l o r development., T h i s method, as re p o r t e d by Mcrganstern et a l . (1965), e l i m i n a t e d i n t e r f e r e n c e by b i l i r u b i n and the need f o r c o r r e c t i o n with a blank standard. U n i t s of measurement were i n mU/ml. The measurement of amylase l e v e l i n serum was accomplished by the method o u t l i n e d by Binderknecht e t a l . (1971). T h i s method was based on r e l e a s e of s o l u b l e s t a r c h fragments due t o r e a c t i o n of amylase with an i n s o l u b l e s t a r c h l a b e l l e d with B e m a z o l b r i l l i a n t Blue. Determination was c o l o r i m e t r i c and u n i t s were Soraogyi u n i t s . The two l i p i d c o n s t i t u e n t s measured were t r i g l y c e r i d e s and c h o l e s t e r o l . ; T r i g l y c e r i d e determination was by the method of Bucclo and David (1973) and i n v o l v e d enzymatic 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 by a m i c r o b i a l l i p a s e and a protease. The h y d r o l y s i s procedure was subsequently coupled to an enzymatic determination of g l y c e r o l through use of absorbance i n a spectrophotometer. T h i s determination was s t a t e d to be s p e c i f i c f o r t r i g l y c e r i d e s . U n i t s o f measurement were mg/dl. C h o l e s t e r o l was analysed by the method of l e v i n e e£ §1* (1967). T h i s was a m o d i f i c a t i o n of an e a r l i e r method and i n v o l v e d the r e a c t i o n o f c h o l e s t e r o l with g l a c i a l a c e t i c a c i d , 26 a c e t i c anhydride and s u l f u r i c a c i d . Determination was by c c l c r i m e t r y and u n i t s were mg/dl. Other compounds which were measured i n the serum were g l u c o s e , i n o r g a n i c phosphate and t h y r o x i n e . Glucose was determined by the method of Bcndar and Mead (1S74). the d e t e r m i n a t i o n r e a c t i o n i n v o l v e d a s p e c t r o p h o t o m e t r y measurement c o r r e c t e d by a blank d e t e r m i n a t i o n . O n i t s were mg/dl. Ino r g a n i c phosphate measurement was based on formation of phosphomclybdic a c i d and subsequent r e d u c t i o n by stannous c h l o r i d e - h y d r a z i n e . T h i s method was described by Hurst (1964), I t was a c o l o r i m e t r i c t e c h n i q u e with u n i t s o f mg/dl. The method d e s c r i b e d by Cheung and Slaunwhite (1976) was used i n the d e t e r m i n a t i o n of the T4 f r a c t i o n of t h y r o x i n e . T h i s method u t i l i z e d radioimmunoassay techniques and measured 14 i n u n i t s of micrograms per d e c i l i t r e . The milk production data used i n t h i s study was obtained from two sources., Data from herds on t h e p r o v i n c i a l Dairy Herd Improvement (DHI) program was obtained from the c e n t r a l data l o c a t i o n i n V i c t o r i a , E. C. The p a r t i c u l a r data c o l l e c t e d i n c l u d e d 305 day l a c t a t i o n y i e l d s of milk, milk f a t and s i l k p r o t e i n f o r both the f i r s t l a c t a t i o n and the l a c t a t i o n i n progress a t the time of b l e e d i n g . Since the number of herds on the f e d e r a l Record of Performance (BOP) program was s m a l l , data were c o l l e c t e d from these herds d u r i n g farm v i s i t s . Type of 27 data c o l l e c t e d from BOP herds vas i d e n t i c a l t o t h a t from DEI herds with the e x c e p t i o n t h a t milk p r o t e i n was not a v a i l a b l e from the BOP herds. Serum data were a v a i l a b l e f o r 701 animals, but only 545 cows were used i n the f i n a l a n a l y s e s . The reason f o r t h i s r e d u c t i o n was the i n a b i l i t y to match some cow i d e n t i f i c a t i o n numbers recorded at the time of blood sampling with those present a t the c e n t r a l data l o c a t i o n s , d e l e t i o n o f o u t l i e r s , and maintenance of op t i m a l s i b group s i z e , , b) S t a t i s t i c a l Models: There were s e v e r a l e f f e c t s to be accounted f o r i n t h i s a n a l y s i s with the s i r e e f f e c t being of prime importance. Since a l l e f f e c t s and c o v a r i a b l e s were not common t o both production and serum t r a i t s , each dependent v a r i a b l e was analysed by the a p p r o p r i a t e model t o e l i m i n a t e unique e f f e c t s , and then j o i n t a nalyses were performed cn ad j u s t e d data to obtain e s t i m a t e s of the v a r i o u s g e n e t i c parameters. Adjustment f a c t o r s were obt a i n e d u s i n g l e a s t sguares c o n s t a n t s from the a p p r o p r i a t e a n a l y s e s . For the milk p r o d u c t i o n t r a i t s , the model on which adjustments were based was as f o l l o w s : Y i j k = u > H i + S j • H S i j • b A i j k > cLijjk • € i j k where u = o v e r a l l mean common to a l l samples. Hi = the e f f e c t o f the i - t h herd. 28 S j = the e f f e c t o f the j - t h season of f r e s h e n i n g . H S i j = the e f f e c t of the i - t h herd s p e c i f i c t o the j - t h season. A i j k = the c o v a r i a b l e age (mo.) to a p p r o p r i a t e l a c t a t i o n s t a r t . b = the c o e f f i c i e n t a s s o c i a t e d with A i j k . L i j k = the c o v a r i a b l e l a c t a t i o n length (days). c = the c o e f f i c i e n t a s s o c i a t e d with L i j k . € i j k .= the unexplained environmental d e v i a t i o n s a s s o c i a t e d with i n d i v i d u a l samples. For the serum t r a i t s , the model on which adjustments were based was as f o l l o w s : T i j k = u + Hi • S j • H S i j • b A i j k + c L i j k + e i jk where u = o v e r a l l mean common t o a l l samples. Hi = the e f f e c t c f the i - t h herd. Sj = t h e e f f e c t c f the j - t h season of b l e e d i n g . H S i j = the e f f e c t o f the i - t h herd s p e c i f i c to the j - t h season, A i j k = the c o v a r i a b l e age (mo.) to s t a r t o f l a c t a t i o n i n which b l e e d i n g occurred, b = the c o e f f i c i e n t a s s o c i a t e d with A i j k . l i j k = the c o v a r i a b l e days from l a c t a t i o n s t a r t to b l e e d i n g date (stage of l a c t a t i o n ) . c = the c o e f f i c i e n t a s s o c i a t e d with L i j k . e i j k = the unexplained environmental d e v i a t i o n s a s s o c i a t e d with i n d i v i d u a l samples. 29 The e f f e c t s of herd, season and herd x season i n t e r a c t i o n were t r e a t e d as f i x e d e f f e c t s . i l l e f f e c t s were assumed to be normally d i s t r i b u t e d and independent with e x p e c t a t i o n s equal t o zero. Constants were estimated and s i g n i f i c a n c e t e s t e d f o r a l l a p p r o p r i a t e terms i n the above models by use of l e a s t squares a n a l y s i s . The raw data were adjusted f o r a l l a p p r o p r i a t e adjustment terms, r e g a r d l e s s o f s i g n i f i c a n c e . T h i s was done r e c o g n i z i n g t h a t an i n s i g n i f i c a n t adjustment term would n e i t h e r a l t e r the data s i g n i f i c a n t l y nor i n t r o d u c e b i a s . Using the adjusted data, the s i r e component of va r i a n c e was estimated from the f o l l o w i n g model Y i j = u + S i + € i j where u = o v e r a l l mean common t o a l l samples. S i = the e f f e c t o f the i - t h s i r e . € i j = the unexplained environmental d e v i a t i o n s a s s o c i a t e d with i n d i v i d u a l samples. S i r e was t r e a t e d as a random e f f e c t and was assumed to be normally d i s t r i b u t e d with e x p e c t a t i o n equal to zero. c) E s t i m a t i o n of Variance Components; R e f e r r i n g t o Tab l e I, t h i s present study u t i l i z e d the f o l l o w i n g components of va r i a n c e (with d e f i n i t i o n s as o u t l i n e d 30 Table I . , A n a l y s i s of v a r i a n c e (ANO?) t a b l e and expected mean squares (EMS) f o r the experimental models. i —i I Sources of v a r i a t i o n 1 d . f . ! EMS | l e a s t Square Cgrrgctj,gn r ! -1 I C o v a r i a b l e s I Aqe (months) I Staqe of l a c t a t i o n 1 ( d a y s ) i 2 | 1 | 1 ! I Herd I d.f.h I 0 2e * k4e*h J Season I d . f . s e I 0*e + k 3 6 2 s e I H x S I d.f.hs I 0*e • k26*hs | Genetic ! ! | S i r e s J d.f. s i r e s I 6*e • k i e ^ s I I n d i v i d u a l / S i r e s I d.f. e i Q2e i shere k1 = (N.,;- ( g Ni.)*/N. . ) / d . f . s i r e s 1 For production t r a i t s , t h i s becomes lenqth of l a c t a t i o n . 3 1 by Falconer (1960): 6 2e •= the component cf v a r i a n c e a s s o c i a t e d with i n d i v i d u a l s w i t h i n s i r e groups. T h i s component o f v a r i a n c e c o n t a i n s 3/4 of the a d d i t i v e g e n e t i c v a r i a n c e {V (A)) and a l l the environmental v a r i a n c e (V(E)). Honadditive g e n e t i c v a r i a n c e s were assumed to be n e g l i g i b l e i n t h i s system. C 2 s = the component of vari a n c e a s s o c i a t e d with d i f f e r e n c e s among s i r e groups. T h i s was assumed t o l e a d t o an estimate of 1/4 V (A). Variances a s s o c i a t e d with a d d i t i v e by a d d i t i v e i n t e r a c t i o n s were assumed to be n e g l i g i b l e i n t h i s system. The v a r i a n c e components of i n t e r e s t i n t h i s study were V (A) , V(E) and t h e phenotypic v a r i a n c e V(P). These were c a l c u l a t e d using the f o l l o w i n g r e l a t i o n s h i p s : V(A) = 4C 2s V(E) = e 2e - 3 0 2 s V(P) = V(A) • V(E) d) Variance of Variance Components: Variances of v a r i a n c e components were c a l c u l a t e d by the formulae given by S e a r l e (1971a). For the components estimated i n t h i s study, the a p p r o p r i a t e sampling v a r i a n c e s were: 1) Var(V ( A ) ) = 16Var(6 2s) where Var(6 2 S ) = 2fl*eN. . 2 (N. «-r1) (A-1) /(N. . -rA) (N, . 2>S2) 2 + ( 4 6 2 e c 2 S l J . . )/(N . .2-S2) + 26*S(N.. 2S2 • S2 2 - 2N. .S3)/(N. . 2 . - S 2 ) 2 32 and »••'..= Z N i . 52 = i N i . z 53 = 2Ni.3 A = the number of s i r e groups N i . = the number of samples i n the i - t h s i r e group 2) Var(V(E)) = V a r ( 6 2 e ) + 9 V a r ( 6 2 s ) - 6cov<e2ee*s) where Var(fi2e) * 26*e/ (N. .--A) c o v ( 6 2 e e 2 s ) = -N. . (A-1) Var ( 6 2 e ) / ( N . .2 - S 2 ) 3) Var«V(P)} = Var(V{A) + V(E)) = Var ( 6 2 s + 6 2 e ) = Var ( 6 2 s ) • V a r ( 6 2 e ) • 2 c o v ( 6 2 e 6 2 s ) €) H e r i t a b i l i t y Estimates; H e r i t a b i l i t y e s t i m a t e s were d e r i v e d as d e s c r i b e d by F a l c o n e r (1960). I n t r a c l a s s c o r r e l a t i o n s (t) between h a l f s i b groups were employed, making use of the f a c t o r s comprising the s i r e and environmental components of v a r i a n c e . In g e n e r a l , hz * 4 t = V(A)/(V(A) • V(E)) = 4 6 2 s / ( 6 2 e * 6 2S) 33 *~) Variance of H e r i t a b i l i t y E s t i m ates: Variances of the h e r i t a b i l i t y e s t i m a t e s were c a l c u l a t e d making use of t h e r e l a t i o n s h i p between h e r i t a b i l i t y and the i n t r a c l a s s c o r r e l a t i o n between h a l f s i b groups. The sampling v a r i a n c e of the i n t r a c l a s s c o r r e l a t i o n f o r h a l f s i b a n a l y s i s was a modified v e r s i o n o f t h a t r e p o r t e d by Robertson (1959). Var(hz) = 16Var(t) = 32f 1+(k1-1)t ] 2(1-t)a/k1 <k1-1) (A-1) 9) C o r r e l a t i o n Estimates; Estimates of g e n e t i c , environmental and phenotypic c o r r e l a t i o n s f o r each p a i r o f t r a i t s measured i n t h i s study were t a b u l a t e d using the f o l l o w i n g formula; r(XaXb) = cov(XaXb)/SXaSXb where r(XaXb) = the a p p r o p r i a t e c o r r e l a t i o n between t r a i t s Xa and Xb (a#b) QXa = the a p p r o p r i a t e standard d e v i a t i o n of the a-th t r a i t 6Xb = the a p p r o p r i a t e standard d e v i a t i o n of the b-th t r a i t and where cov (XaXb) was the s o l u t i o n o f a rearrangement of the f o l l o w i n g g e n e r a l formula; Var (Xa+Xb) = e aXa • €*Xb • 2cov(XaXb) 34 h) Variance of C o r r e l a t i o n Estimates: Variances of the c o r r e l a t i o n s c a l c u l a t e d i n t h i s study were estimated by the approximation given by Scheinberg (1966). Es t . Var (rXaXb) = 2 u r 2 (XaXb)/k 1 2 f ( s V 2 a / d . f , s i r e s * w 2v 2a/d.f.e)/4C*a *• (svzb/d.f. s i r e s + w*v 2b/d.f.e)/40*b • s[ (VaVb + V 2 a b ) / d . f . s i r e s • w2 (vavb • v 2 a b ) / d . f. e) ]/2cov 2 (Xaxb) - (sVaVab/d.f. s i r e s + w 2vavab/d.f.e)/6 2acov(XaXb) - (sVbVab/d.f. s i r e s • w 2vbvab/d.f. e) /O 2bcov (XaXb) • ( s V 2 a b / d . f . s i r e s • w 2v 2ab/d.f.e)/26 2a0 2b} where Va = s i r e mean sguare a s s o c i a t e d with t r a i t a Vb = s i r e mean square a s s o c i a t e d with t r a i t b Vab = s i r e mean co v a r i a n c e f o r t r a i t s a and b va = r e s i d u a l mean sguare a s s o c i a t e d with t r a i t a vb = r e s i d u a l mean square a s s o c i a t e d with t r a i t b vab = r e s i d u a l mean c o v a r i a n c e f o r t r a i t s a and b and u = 16, 1 and 1 f o r t h e g e n e t i c , environmental and phenotypic c o r r e l a t i o n s r e s p e c t i v e l y s = 1, 9 and 9 f o r the g e n e t i c , environmental and phenotypic c o r r e l a t i o n s r e s p e c t i v e l y w = 1, k1+3 and k1-3 f o r the g e n e t i c , environmental and phenotypic c o r r e l a t i o n s r e s p e c t i v e l y 35 BESPITS JND DISCUSSION Before s u b j e c t i n g the data t o a n a l y s e s f o r the g e n e t i c parameters, l e a s t squares adjustments f o r i d e n t i f i a b l e , s y s t e m a t i c environmental e f f e c t s were undertaken. , The e f f e c t s of herd, season, herd by season i n t e r a c t i o n , and two c o v a r i a b l e s were taken i n t o account., Age at l a c t a t i o n s t a r t , one of the c o v a r i a b l e s , was common to a l l t r a i t s . For f i r s t l a c t a t i o n r e c o r d s , t h i s was the age to s t a r t of f i r s t l a c t a t i o n . For both c u r r e n t p r o d u c t i o n and serum t r a i t s , t h i s c o v a r i a b l e was the age at s t a r t of the l a c t a t i o n i n which serum sampling took place. The second c o v a r i a b l e was l e n g t h of l a c t a t i o n i n the case of the milk production t r a i t s and stage o f l a c t a t i o n a t time of b l e e d i n g i n the case of the serum c o n s t i t u e n t s . The a c t u a l l e a s t sguares c o n s t a n t s a s s o c i a t e d with herd and the i n t e r a c t i o n term were of l i t t l e i n t e r e s t s i n c e no s p e c i f i c i n f e r e n c e s were to be drawn from these e f f e c t s . However, t h e l e a s t sguares constants a s s o c i a t e d with the two seasons and the two c o v a r i a b l e s allowed us to s t a t e i n which season the l e v e l of a t r a i t was higher or how the l e v e l was changing with r e s p e c t to the c o v a r i a b l e . For t h i s reason, an abridged t a b l e of l e a s t sguares c o n s t a n t s i s presented i n Table I I . T h i s t a b l e shows the t r e n d s f o r the seasons and the c o v a r i a b l e s i n a form more c o n c i s e than w r i t t e n t e x t . The most n o t i c e a b l e of these l e a s t squares c o n s t a n t s were Table I I . Least squares constants associated with suamer and winter seasons and with the covariables. " - —• — — — — — i ' * I T r a i t | Sumner Winter Age Length Stage | *== = = = = M = ========= ========= =========== ============== = ==-=====.f 1 H i l k l | -214.4 214. 4 41.98 28.56 na | | Fat 1 | -6. 351 6. 351 1. 6C5 1. 250 na | I P r o t l | -5. 454 5. 454 1.549 .9522 na | I HilkC | -195.3 195.3 22. 36 34.26 na | I Fat C | -5. 708 5. 708 . 8728 1.272 na | I Protc | -4.556 4.556 . 6318 1. 127 na | 1 Ca | . 0379 -.0379 -.0021 na .0005 | I P04 | . 0139 -.0139 -.0104 na .0011 | ! Glue j -2. 090 2- 090 .0194 na . 0 140 | I BUN | . 1333 -.1333 0178 na .0098 | ! U r i c | . 1130 -.1130 -.0001 na -.0004 | I Chol | -6. 949 6. 949 -. 1069 na .0523 | I T P | . 0406 -.0406 . 0100 na -.0006 | I Alb | -.2449 .2449 . 0004 na .0003 | 1 B i l i | -.0049 .0049 .0002 na -.0002 | 1 Alk P | -.6511 .6511 -. 1720 na .0187 | | SGOT | -.4055 . 4055 -.0543 na .0536 | I Creat | -. 0693 . 0693 -.0004 na -.0000 | 1 T r i g | . 0890 -.0890 0122 na .0030 | 1 Na | -.8073 .8073 -.0154 na .0016 J I K 1 .0167 -.0167 -.0009 na -.0000 | 1 CI | . 6487 -.6487 -.0071 na .0050 | I HC03 | -.9059 . 9059 -.0044 na -.0019 | 1 T4 | 2352 .2352 -.0087 na .0047 | I fiffiyl | -8. 706 8. 706 .5502 na .0122 | 3 7 those a s s o c i a t e d with age i n the f i r s t and the c u r r e n t l a c t a t i o n s . The l e a s t sguares c o n s t a n t s f o r a l l t h r e e measures of production were c o n s i d e r a b l y higher f o r f i r s t l a c t a t i o n compared to those f o r c u r r e n t l a c t a t i o n . T h i s i n d i c a t e d t h a t , over the s m a l l e r range of age present i n f i r s t l a c t a t i o n s {23-36 months), age had a more pronounced e f f e c t which was r e f l e c t e d i n the higher a s s o c i a t e d c o n s t a n t s . Current l a c t a t i o n p r o d u c t i o n , with an age range o f 23-157 months, d i d not show as s t r o n g a r e l a t i o n s h i p and consequently had much lower c o n s t a n t s f o r age. The c o e f f i c i e n t o f d e t e r m i n a t i o n (B 2) f o r the t o t a l model i s a measure of the p o r t i o n of t o t a l v a r i a b i l i t y accounted f o r by the environmental e f f e c t s l i s t e d above. For the t r a i t s examined i n t h i s study, the t o t a l B 2 ranged from 0,20 8 f o r a l k a l i n e phosphatase to 0.704 f o r albumin. T h i s i n d i c a t e d the r e l a t i v e l y s m a l l importance o f the s y s t e m a t i c , environmental e f f e c t s u t i l i z e d i n t h i s study i n determining the t o t a l v a r i a b i l i t y of a l k a l i n e phosphatase. For serum albumin l e v e l s , however, these e f f e c t s were determining a l a r g e p o r t i o n of the t o t a l v a r i a b i l i t y . The p a r t i a l B 2 y i e l d e d an i n d i c a t i o n of the r e l a t i v e importance of the separate e f f e c t s i n the adjustment model. Thus the p a r t i a l 8 2 went beyond whether the adjustment f o r t h a t e f f e c t was s i g n i f i c a n t , and became a d i s c r i m i n a t i n g s t a t i s t i c f o r the r e l a t i v e importance o f t h a t adjustment. C o e f f i c i e n t s of d e t e r m i n a t i o n are summarized with l e a s t squares means and standard e r r o r s i n Table I I I . , The e f f e c t of herd was s i g n i f i c a n t f o r a l l t r a i t s i n t h i s 38 Table I I I . Least square means and associated standard errors (SE) with R* f o r a l l co r r e c t i o n terms. T r a i t | Mean SE T | Herd Season HxS Aqe lenqth Staqe T o t a l | M i l k l | 5994kq 45. 2 I .256* .029* .085* . 012* .068* na .494 | Fat 1 | 222.kq 1. 79 I .224* .017* .086* .012* .087* na . 465 | P r o t l | 195. kq 1. 52 I .262* .0 20* .064 .017* .054* na .464 | MilkC | 7160kq 66. 2 I .184* .009* .050* .108* . 127* na .553 | Fat C | 262. kq 2. 59 I .166* .005* .056* .120* .127* na . 505 | ProtC | 230.kq 2. 1 1 I . 198* . 005* .053* .095* .142* na .533 | Ca | 9. 54mq/dl .021 I .230* .003 .206* .008* na .002 .471 | P04 | 4. 98mq/dl . 039 I .114* . 000 .1 18* .072* na .004 .354 | Glue I 5a.1mq/dl . 316 I .188* .036* .298* . 002 na .006* .561 | BUN | 114. 1mq/dl . 125 I .333* . 001 .304* .010* na .014* .671 | U r i c t 1. 07mq/dl .011 I .165* . 104* . 1 19* , 00 0 na .005* . 438 | Chol | 206.mq/dl 1.78 I .210* .018* .121* .003 na .004 .375 | T P | 7.62q/dl . 022 I . 138* .003 . 086* .154* na .003 .481 | Alb | 3.66g/dl .013 I . 302* . 189* .120* .000 na .001 .704 | B i l i | .170my/dl . 00 4 I .177* .002 .063 .004 na .010* .317 | Mk P | UO. 7 mil/ml . 960 I .089* . 001 .060 .038* na .002 . 208 | SGOT | 136. mU/ml 1. 18 I .289* .000 . 1 33* .002 na .008* . 447 | Creat | .9 57mq/dl .005 I .128* .158* .189* .004* na .000 . 552 | T r i g 1 9. 68mq/dl . 121 I .243* .001 .136* .009* na .002 . 402 | Na l 141. meq/1 . 127 I .272* . 035* .197* .010* na .000 . 542 | K 1 4.24raeq/l .016 I .142* . 001 . 124* .003 na .000 .310 | CI | 97.2neq/l . 108 I .237* .029* .240* .003 na .006* .570 | HC03 | 23.3meq/l .080 I .276* .092* .223* .002 na .001 .622 | T4 | 5. 25yug/dl . 058 | . 131* .016* .216* .017* na .024* .470 | A my 1 j 193. SOD. 0 3. 58 I .159* .008* .073 .024* na .000 .306 | - 1 * S i g n i f i c a n t at P<0.05 39 study, accounting f o r between S,9% and 33,3% of t o t a l v a r i a b i l i t y . „. T h i s r e f l e c t e d the e f f e c t s of n u t r i t i o n , management and microenvironment a s s o c i a t e d with each herd, and agreed with e a r l i e r papers (flewett 1974, Payne e t a l . 1974, Rowlands and Hanston 1976) which s t a t e d that herd was the s i n g l e most important f a c t o r i n determining the l e v e l o f serum c o n s t i t u e n t s . The other f a c t o r s i n the model were not as u n i v e r s a l l y s i g n i f i c a n t or as important as the herd e f f e c t . They are d i s c u s s e d i n d e t a i l at t h i s p o i n t . Season was s i g n i f i c a n t f o r a l l milk p r o d u c t i o n t r a i t s but accounted f o r only a small p r o p o r t i o n of the v a r i a b i l i t y . Adjustment f o r season has l o n g been r e c o g n i z e d by v a r i o u s d a i r y r e c o r d i n g schemes, and t h i s adjustment was warranted i n view of the seasonal changes i n many aspects o f the cow's environment. Included i n these s e a s o n a l changes were the change from pasture to s t o r e d feed, a management system s t i l l present on many farms. Other farms u t i l i z e d s t o r e d feeds on a year-round b a s i s . A l s o , s i n c e a l l herds d i d not experience a p a r a l l e l s e a s o n a l change i n f e e d , a s i g n i f i c a n t i n t e r a c t i o n between herd and season was expected. T h i s was found f o r a l l production t r a i t s with the e x c e p t i o n of f i r s t l a c t a t i o n p r o t e i n y i e l d . I t was noted t h a t season was s i g n i f i c a n t f o r a l l production t r a i t s but accounted f o r a much l a r g e r p r o p o r t i o n of the v a r i a b i l i t y i n the c u r r e n t l a c t a t i o n t r a i t s . T h i s i n d i c a t e d t h a t , while the l e a s t sguares c o n s t a n t s were s i m i l a r {Table I I ) , there was r e l a t i v e l y more no r e s i d u a l e r r o r i n v o l v e d in the c u r r e n t l a c t a t i o n t r a i t s . , T h i s r e s u l t e d i n l e s s v a r i a b i l i t y accounted f o r by season and thus a lower p a r t i a l R 2. Adjustment f a c t o r s f o r age and l a c t a t i o n length have a l s o been u t i l i z e d as a means of s t a n d a r d i z i n g production r e c o r d s . The r a t i o n a l e f o r t h i s was r e i n f o r c e d by the s i g n i f i c a n c e of these two f a c t o r s i n determining the v a r i a b i l i t y o f a l l milk production t r a i t s . , A s i m i l a r s i t u a t i o n e x i s t e d f o r age and l e n g t h as d i d f o r s e asonal e f f e c t s . Regarding age, the l e a s t sguares c o n s t a n t s were higher f o r f i r s t l a c t a t i o n compared to c u r r e n t l a c t a t i o n t r a i t s , yet p a r t i a l R z were h i g h e r f o r c u r r e n t l a c t a t i o n t r a i t s . T h i s i n d i c a t e d t h a t although the r e g r e s s i o n o f f i r s t l a c t a t i o n on age e x h i b i t e d a l a r g e r s l o p e , the r e s i d u a l v a r i a b i l i t y around t h i s r e g r e s s i o n was l a r g e . T h i s r e s u l t e d i n lower p a r t i a l R 2, an i n d i c a t i o n of the lower o v e r a l l s t r e n g t h of the r e g r e s s i o n . For l e n g t h o f l a c t a t i o n , l e a s t sguares c o n s t a n t s were s i m i l a r f o r f i r s t and c u r r e n t l a c t a t i o n t r a i t s , yet r e s i d u a l v a r i a b i l i t y , with r e s p e c t to l a c t a t i o n l e n g t h , was g r e a t e r i n f i r s t l a c t a t i o n . Again, t h i s r e s u l t e d i n a lower p a r t i a l B 2 f o r f i r s t l a c t a t i o n t r a i t s . , For the serum c o n s t i t u e n t s , the s i g n i f i c a n c e and i n t e r p r e t a t i o n of the adjustment terms was not as s t r a i g h t f o r w a r d as f o r the p r o d u c t i o n t r a i t s . Although herd e f f e c t s were s i g n i f i c a n t and, i n g e n e r a l , accounted f o r the 4 1 l a r g e s t p o r t i o n of the v a r i a b i l i t y , the other adjustment f a c t o r s v a r i e d g r e a t l y with regards to s i g n i f i c a n c e and r e l a t i v e importance. „ Herd e f f e c t on l e v e l s o f serum t r a i t s was a r e f l e c t i o n of changes i n the metabolism brought about by the d i f f e r e n c e s i n n u t r i t i o n , f e e d i n g , management, and microenvironment among herds. I t was expected t h a t v a r i o u s metabolic a c t i v i t i e s i n the animal w i l l be a l t e r e d due to d i f f e r e n c e s i n i n p u t s to the a n i i r a l and d i f f e r e n c e s i n the environment i n which the animal f u n c t i o n s . T h i s a l t e r a t i o n was expected to have i t s e f f e c t both d i r e c t l y on the metabolic pathway i n v o l v i n g the p a r t i c u l a r serum c o n s t i t u e n t s , or i n d i r e c t l y by a f f e c t i n g o t h e r c o n s t i t u e n t s which are i n t e r r e l a t e d . Seasonal e f f e c t s were expected to c h r o n i c l e the seasonal changes i n i n p u t s and environment. S p e c i f i c a l l y , the change from pasture to s t o r e d f e e d a l t e r e d g r e a t l y the n u t r i t i o n a l i n p u t s t o the animal's metabolism and a q u a n t i t a t i v e change i n some serum t r a i t s c o u l d be expected. As p r e v i o u s l y mentioned, i f t h e s e s e a s o n a l changes were not p a r a l l e l over a l l herds, a herd by season i n t e r a c t i o n c o u l d be expected. The c o v a r i a b l e s a s s o c i a t e d with t h e serum t r a i t s , age at l a c t a t i o n s t a r t and stage of l a c t a t i o n at time o f blood sampling, were both a s s o c i a t e d with changes i n metabolism over time. As the animal matures, metabolic and hormonal changes occur and a f f e c t the l e v e l s of some serum c o n s t i t u e n t s . As stage of l a c t a t i o n proceeded, hormonal and n u t r i t i o n a l balance 42 s t r e s s were both i n v o l v e d i n the a l t e r i n g of some serum c o n s t i t u e n t s . Calcium and i n o r g a n i c phosphate, which are i n t e r r e l a t e d i n a number of body systems, showed the same trends f o r the adjustment f a c t o r s . Herd, herd by season i n t e r a c t i o n and age e f f e c t s were s i g n i f i c a n t , T h i s was i n agreement with Tumbleson et a l . (1973b) and Kitchenham e t •••al. (1975) and (1976), Calcium and i n o r g a n i c phospate have been r e p o r t e d (Boss and H a l l i d a y 1976) t o be a f f e c t e d by season, but other r e p o r t s (Payne et a l , 1974) found no such s i g n i f i c a n c e . Stage of l a c t a t i o n has been v a r i o u s l y r e p o r t e d to have a s i g n i f i c a n t e f f e c t (Rowlands e t a l , „ 1975) or a n o n s i g n i f i c a n t e f f e c t (Hewett 1974) on c a l c i u m l e v e l s , so the f a c t t h a t t h i s study re p o r t e d an i n s i g n i f i c a n t l a c t a t i o n a l e f f e c t was not s e r i o u s l y d i s r u p t i v e . Glucose was s i g n i f i c a n t l y a f f e c t e d by herd, season, herd by season i n t e r a c t i o n and stage of l a c t a t i o n . Seasonal i n f l u e n c e on serum glucose has not been p r e v i o u s l y r e p o r t e d as s i g n i f i c a n t (Payne e t a l . 1974). The s i g n i f i c a n c e of age e f f e c t s on glucose have been i n disagreement (Kitchenham et a l . 1975* Kitchenham and Rowlands 1976 and Tumbleson and Hutcheson 1971) but was i n s i g n i f i c a n t i n t h i s present study. BON was s i g n i f i c a n t l y a f f e c t e d by herd, i n t e r a c t i o n , age and stage o f l a c t a t i o n . In view of the e f f e c t of d i e t on serum l e v e l s of BON ( L i t t l e and Hanston 1972, Hanston et a l . 1975, and P r e w i t t e t a l , 1971), i t was expected to be s i g n i f i c a n t . However, as p o i n t e d out e a r l i e r , management on many farms now i n c l u d e s s t o r e d feeds e x c l u s i v e l y . T h i s would l e s s e n the within herd seasonal e f f e c t on any c o n s t i t u e n t s l a r g e l y a f f e c t e d by major changes i n d i e t . T h i s i n t u r n i n d i c a t e d support f o r the s i g n i f i c a n c e o f the i n t e r a c t i o n term. U r i c a c i d was s i g n i f i c a n t l y a f f e c t e d by a l l f a c t o r s with the e x c e p t i o n of age. The serum l i p i d s measured were c h o l e s t e r o l and t r i g l y c e r i d e s , although t h e r e was l i t t l e s i m i l a r i t y between these c o n s t i t u e n t s f o r the s i g n i f i c a n c e o f the adjustment terms. C h o l e s t e r o l was adjusted f o r herd, season and i n t e r a c t i o n e f f e c t s while t r i g l y c e r i d e s were adjusted f o r herd, i n t e r a c t i o n and age e f f e c t s . The above s i t u a t i o n f o r c h o l e s t e r o l was i n general agreement with p r e v i o u s l y published s t u d i e s with the ex c e p t i o n t h a t age was noted by Peterson and Ha I d e m (1978) and by Tumbleson and Hutchescn (1971) to have a s i g n i f i c a n t e f f e c t on c h o l e s t e r o l l e v e l . T h i s age e f f e c t was dependent on the range of age present, which could e x p l a i n the f i n d i n g i n t h i s study. , Measures of p r o t e i n i n the serum were t o t a l p r o t e i n and albumin. Albumin was s i g n i f i c a n t l y a f f e c t e d by herd, age and i n t e r a c t i o n , while t o t a l p r o t e i n r e c e i v e d f u r t h e r adjustment f o r age e f f e c t s . T h i s was i n c l o s e agreement with Tumbleson e t a l . (1973b) who r e p o r t e d t o t a l p r o t e i n but not albumin to be s i g n i f i c a n t l y a f f e c t e d by age. In e a r l y l a c t a t i o n , Rowlands e t a l . (1975) and L i t t l e (1974) found albumin and t o t a l p r o t e i n both to be s i g n i f i c a n t l y a f f e c t e d by 44 stage o f l a c t a t i o n , a r e s u l t not forthcoming from the present study. Hewett (1974), u s i n g a range o f l a c t a t i o n stage more c l o s e l y approximating t h a t i n the present study, found no r e l a t i o n s h i p of stage o f l a c t a t i o n with albumin. B i l i r u b i n was a f f e c t e d by herd and stage of l a c t a t i o n . Tumbleson and Hutcheson (1971) and Mylrea and Healy (1968) d i f f e r e d with the present study i n s t a t i n g b i l i r u b i n was a l s o a f f e c t e d by age. A l k a l i n e phosphatase was a f f e c t e d by herd and age. T h i s was i n agreement with previous s t u d i e s (Tumbleson el; al,. 1973a). SGOT was ad j u s t e d f o r herd, i n t e r a c t i o n and stage of l a c t a t i o n . T h i s i n d i c a t e d t h a t n u t r i t i o n a l e f f e c t s which comprised p a r t of the herd and i n t e r a c t i o n terms were s i g n i f i c a n t while c l i m a t i c changes were not. The r e s u l t s f o r SGOT i n the present study d i f f e r e d from past s t u d i e s i n t h a t age has been c i t e d as an e f f e c t (Peterson and Waldern 1978)• A l l f a c t o r s except stage o f l a c t a t i o n were u t i l i z e d i n a d j u s t i n g c r e a t i n i n e l e v e l s . The a v a i l a b l e l i t e r a t u r e on t h i s c o n s t i t u e n t supported t h i s present f i n d i n g (Peterson and Haldern 1978 and Hylrea and Healy 1968). Sodium, potassium, c h l o r i d e and bi c a r b o n a t e a re e l e c t r o l y t e s i n the blood which are important i n many b o d i l y f u n c t i o n s and are i n s t r u m e n t a l i n ma i n t a i n i n g osmotic e g u i l i b r i u m . A l l fo u r c o n s t i t u e n t s were a f f e c t e d by herd, season and i n t e r a c t i o n f a c t o r s with the e x c e p t i o n of the sea s o n a l e f f e c t on potassium. A d d i t i o n a l l y , sodium was 45 s i g n i f i c a n t l y a f f e c t e d by age and c h l o r i d e by stage of l a c t a t i o n . The absence o f age e f f e c t s was g e n e r a l l y supported by previous s t u d i e s (Tumbleson e t a l . 1973b and Kitchenham et a l . 1976). Thyroxine was s i g n i f i c a n t l y a f f e c t e d by a l l f a c t o r s . T h i s agreed with r e s u l t s of Flamboe and Beineke 11959) and Mixner et a l . (1962). Amylase was s i g n i f i c a n t l y a f f e c t e d by herd, season and age. Once s i g n i f i c a n t s y s t e m a t i c , environmental e f f e c t s were e l i m i n a t e d from the da t a , i t was presumed that only g e n e t i c and random environmental v a r i a b i l i t y remained. Because of the design o f t h i s present study, the g e n e t i c and environmental components were s e p a r a b l e with high r e l a t i v e e f f i c i e n c y . T h i s s e p a r a t i o n y i e l d e d e s t i m a t e s of variance components, h e r i t a b i l i t i e s , and g e n e t i c , environmental and phenct ypi c c o r r e l a t i o n s . Since t h i s present study estimated only the a d d i t i v e p o r t i o n of the g e n e t i c v a r i a b i l i t y and had no means of e s t i m a t i n g n o n a d d i t i v e g e n e t i c v a r i a b i l i t y , i t was assumed i n t h i s study t h a t the environmental parameters i n c l u d e d a l l e f f e c t s e x c l u s i v e o f the a d d i t i v e e f f e c t . Table I? r e p r e s e n t s a summary of the g e n e t i c , environmental and phenotypic v a r i a n c e s and the h e r i t a b i l i t i e s a s s o c i a t e d with each t r a i t . I t was apparent that some g e n e t i c components o f variance and some h e r i t a b i l i t i e s were a r b i t r a r i l y s e t to zero. T h i s was i n s t i g a t e d i n cases where the g e n e t i c v a r i a n c e was Table IV. Variance components and h e r i t a b l i t i e s with associated SE f o r the i n d i v i d u a l t r a i t s . T r a i t | k V (A) ±SE V (E)±SE V(P)±SE h*iSE M i l k l | 15. 25 68728±64289 571378±69953 640106±43127 .10741.0976 Fat 1 | 15. 25 153.9±113.9 852.2±116.2 1006.168.37 .15301.1078 P r o t l | 13. 56 106.0±83.77 576.2i85.33 682.3±49.09 .15541.1172 MilkC | 17. 35 459265+217238 903688±187688 1362593193041 .33701.1382 Fat C | 17. 35 587.5±297.6 1495.±265.9 2082.1138.8 .28211.1270 ProtC | 15. 52 534.7±249.6 809.2±210.9 1344.±99. 14 .39791.1560 Ca | 18. 10 0.0 . 1950±.0167 .19501.1190 0.0 P04 | 17. 48 ,0086±.0409 ,6078±.0550 .6164±.0384 .01391.0664 G luc | 18. 13 0.0 42.78±3.661 42.78±2.618 0.0 BON | 18. 14 .3057±.4792 6.312±.5952 6.618±.4060 .0462±.0718 Uric | 18. 17 .0002±.0034 .05481.0047 .0550±.0034 .0045±.0616 Chol | 18. 06 0. 0 1352.±116. 1 1352.±82.92 0.0 T P | 18. 13 .0015t.0133 .2119±.0184 •2134±.0131 .00701.0624 Alb | 18. 13 .0064±.0063 .0689±.007T .0753±.0046 .08521.0810 B i l i | 18. 03 0. 0 .0068±.0006 .0068±.0004 0.0 Alk P | 18. 06 116.4±56.74 272.4±49.94 388.8±25.65 .29941.1283 SGOT | 17. 93 30.53±43.73 554.9153.46 585.4136.14 .05221.0739 Creat | 18. 28 .0035±.0016 .00731.0014 .C108±.0007 .32481.1328 T r i g J 18. 17 0.0 6.3391.5417 6.3391.3876 0.0 Na | 17. 83 0. 0 6.9501.6025 6.9501.4290 0.0 K | 17. 83 .0144*.0108 .09721.0113 .11161.0070 . 12881. 0921 CI | 17. 87 .0837±.3218 4.8121.4310 4.8961.3020 .01711.0657 HC03 | 17. 87 0. 0 2.7201.2354 2.7201.1677 0.0 T4 | 18. 44 0.0 1.4721.1244 1.4721.0893 0.0 Amyl | 17. 82 1082. ±6 30. 1 4265.1601.6 5347.1341.9 .20241.1085 47 n e g a t i v e , r e s u l t i n g i n a n e g a t i v e h e r i t a b i l i t y . Since the t h e o r e t i c a l lower l i m i t of h e r i t a b i l i t y i s zero, a negative value was taken as a s t a t i s t i c a l estimate of a h e r i t a b i l i t y t h a t was very c l o s e to zero. Taken another way, a negative h e r i t a b i l i t y was one t h a t was not s i g n i f i c a n t l y d i f f e r e n t from zero. Comparison of the components of variance estimates from t h i s and previous s t u d i e s was p o s s i b l e f o r the milk production t r a i t s . The present study used both f i r s t and c u r r e n t l a c t a t i o n s . I t was noted t h a t c u r r e n t l a c t a t i o n s were indeed f i r s t l a c t a t i o n s i f the animals were sampled d u r i n g t h e i r f i r s t l a c t a t i o n . Any comparisons between estimates based cn f i r s t or on c u r r e n t l a c t a t i o n s were s u b j e c t to c o n s i d e r a t i o n s with regards to the degree to which the d i f f e r e n t l a c t a t i o n measures comply with the assumptions r e g u i r e d by modern g e n e t i c theory. H i s t o r i c a l l y , f i r s t l a c t a t i o n r e c o r d s have been c o n s i d e r e d more r e l i a b l e i n s o f a r as they are l e s s b i a s e d by s e l e c t i o n or p r e f e r e n t i a l f e e d i n g and management. Estimated components of v a r i a n c e r e p o r t e d by Butcher et a l . (1967) on a l l l a c t a t i o n s agreed reasonably w e l l with those estimated from c u r r e n t l a c t a t i o n s i n t h i s present study. Variance components a s s o c i a t e d with f i r s t l a c t a t i o n were somewhat lower than these e s t i m a t e s . T h i s d i s c r e p a n c y c o u l d be due to a number of f a c t o r s . , S i n c e f i r s t l a c t a t i o n p r o d u c t i o n was lower than c u r r e n t l e v e l p r o d u c t i o n , i t appeared t h a t the HQ v a r i a n c e and the mean o f these d i s t r i b u t i o n s were c o r r e l a t e d , i n d i c a t i n g a nonnormal d i s t r i b u t i o n . , Another p o s s i b l e cause c o u l d have been that o l d e r s i r e s tended t o have daughters i n l a c t a t i o n s subsequent to the f i r s t l a c t a t i o n , while younger s i r e s would have daughters predominantly i n t h e i r f i r s t l a c t a t i o n s . T h i s i n d i c a t e d t h a t s i r e e f f e c t and age were confounded t o some extent or t h a t the age adjustment was somewhat inadequate f o r c u r r e n t l a c t a t i o n . The h e r i t a b i l i t i e s f o r the production t r a i t s f a l l i n t o the range g e n e r a l l y r e p o r t e d i n t h e l i t e r a t u r e (Butcher e t a l . 1967, Johnson 1957). H e r i t a b i l i t y e stimates f o r the c u r r e n t l a c t a t i o n p roduction t r a i t s were c o n s i d e r a b l y higher than those f o r f i r s t l a c t a t i o n . T h i s may have a r i s e n due t o two a s p e c t s o f the s t a t i s t i c a l a n a l y s i s used i n t h i s study. As p r e v i o u s l y mentioned, s i r e e f f e c t and age were somewhat confounded i n c u r r e n t l a c t a t i o n with the r e s u l t t h a t the a d d i t i v e v a r i a n c e s and the h e r i t a b i l i t i e s were i n f l a t e d . A l s o , f i r s t l a c t a t i o n r e c o r ds were completed over a number of years preceeding the year of blood sampling. Since age, not year, was accounted f o r i n the model, an inadequate adjustment may have occ u r r e d with a r e s u l t i n g i n f l a t i o n of environmental variance f o r f i r s t l a c t a t i o n . T h i s would tend to reduce the h e r i t a b i l i t y f o r f i r s t l a c t a t i o n t r a i t s . In d i s c u s s i n g the h e r i t a b i l i t i e s of serum t r a i t s an important p o i n t must be c o n s i d e r e d . For production t r a i t s , the 49 adjustment model i n v o l v e d e f f e c t s and c o v a r i a b l e s t h a t were, with one minor e x c e p t i o n , s i g n i f i c a n t . , For many serum t r a i t s , net a l l of the e f f e c t s i n the adjustment model were s i g n i f i c a n t . T h i s became important i n t h a t i f c e r t a i n terms were i n s i g n i f i c a n t then the environmental v a r i a n c e would tend to be overestimated. T h i s arose from two causes. , F i r s t l y , an i n s i g n i f i c a n t adjustment term did not s i g n i f i c a n t l y reduce the e r r o r sums of sguares. However, the i n s i g n i f i c a n t term s t i l l removed degrees of freedom from the e r r o r l i n e i n the s i r e a n a l y s i s . These had the combined e f f e c t of o v e r e s t i m a t i n g the environmental v a r i a n c e and thus underestimating the g e n e t i c v a r i a n c e . The wasted degrees of freedom became e s p e c i a l l y important when herd or i n t e r a c t i o n terms were i n s i g n i f i c a n t , s i n c e 34 degrees of freedom were i n v o l v e d f o r both terms. I f these terms were i n s i g n i f i c a n t then the h e r i t a b i l i t y estimated f o r t h at t r a i t may have been underestimated. H e r i t a b i l i t y e stimates f o r serum c o n s t i t u e n t s were i n c l o s e agreement with estimates present i n the l i t e r a t u r e , albumin was s i g n i f i c a n t l y h e r i t a b l e i n t h i s study (h 2=0.085), an estimate i n agreement of s i g n i f i c a n c e , i f not magnitude, with Kitchenham and Rowlands (1976), B e t t i n i et a l . (1975) and Rowlands etaJL. (1974), The o v e r a l l impression from the previous r e s e a r c h was t h a t the s i g n i f i c a n t , low h e r i t a b i l i t y estimated f o r albumin i n t h i s study was not unsupported i n view of previous e s t i m a t e s and a s s o c i a t e d e r r o r s of e s t i m a t i o n . 50 A l k a l i n e phosphatase was estimated to have a moderate h e r i t a b i l i t y (0.299). T h i s estimate was higher than those p r e v i o u s l y r e p o r t e d but was i n agreement o f s i g n i f i c a n c e ( B e t t i n i e t a l . 1975, Peterson and Haldern 1978). I t was f u r t h e r noted t h a t the i n t e r a c t i o n adjustment term was i n s i g n i f i c a n t , i n d i c a t i n g t h a t t h i s e s t imate may be an underestimate. The h e r i t a b i l i t y estimate f o r c r e a t i n i n e was moderate t o high (0.325). Peterson and Waldern (197 8) r e p o r t e d a r e p e a t a b i l i t y f o r t h i s c o n s t i t u e n t of 0.514 i n d i c a t i n g t h a t the present e s t i m a t e of h e r i t a b i l i t y was i n a corresponding range. Potassium was h e r i t a b l e (0.129), a r e s u l t i n agreement with s t u d i e s by Kitchenham and lowlands (1976) and Rowlands e t a l . (1974). The magnitude of p r e v i o u s e s t i m a t e s were s u b s t a n t i a l l y higher than the present one but standard e r r o r s were a l s o c o r r e s p o n d i n g l y h i g h e r i n d i c a t i n g the lower r e l a t i v e r e l i a b i l i t y of the higher e s t i m a t e s . Amylase, with a moderate h e r i t a b i l i t y of 0.202, had no c o r r o b o r a t i o n from previous s t u d i e s . In view of i t s magnitude and s m a l l r e l a t i v e standard e r r o r , i t i s proposed t h a t the present estimate was a r e l i a b l e one. Given t h a t the i n t e r a c t i o n adjustment was i n s i g n i f i c a n t f o r amylase, t h i s h e r i t a b i l i t y may indeed be an underestimate. Two c o n s t i t u e n t s u t i l i z e d i n t h i s study, BUN and SGOT, e x h i b i t e d h e r i t a b i l i t i e s below the c r i t i c a l s i g n i f i c a n c e l e v e l . These e s t i m a t e s were 0.046 and 0.052 f o r BON and SGOT 51 r e s p e c t i v e l y . Kitchenham and Rowlands (1976) r e p o r t e d a high h e r i t a b i l i t y and B e t t i n i e t a l . (1975) r e p o r t e d a low h e r i t a b i l i t y f o r BON, both e s t i m a t e s being s i g n i f i c a n t . Rowlands e t a l . (1974) reported a non s i g n i f i c a n t h e r i t a b i l i t y f o r BON, but t h i s estimate was done on animals completely removed from the age range present i n t h i s study. SGOT has been r e p o r t e d as s i g n i f i c a n t l y h e r i t a b l e ( B e t t i n i £t a,l. 1975) and as not s i g n i f i c a n t l y h e r i t a b l e (Furtmayr 1975). I t was f u r t h e r noted t h a t the standard e r r o r s o f h e r i t a b i l i t y f o r these two components allow a range of confidence w i t h i n which a nonzero value f o r the p o p u l a t i o n estimate w i l l e x i s t . S i n c e , f o r these two c o n s t i t u e n t s , t h i s range o f confidence reached i n t o values t h a t could prove e f f e c t i v e i n a s e l e c t i o n program, BON and SGOT may be i n t e r e s t i n g i n s p i t e of t h e i r i n s i g n i f i c a n t h e r i t a b i l i t i e s . The remaining serum t r a i t s were not s i g n i f i c a n t l y h e r i t a b l e . T h i s may have been due t o two separate causes. One p o s s i b i l i t y was t h a t there was no a d d i t i v e g e n e t i c v a r i a n c e present i n d i c a t i n g f i x a t i o n o f t h e genotype r e s p o n s i b l e f o r the p a r t i c u l a r t r a i t . ; The other p o s s i b l e cause c o u l d have been f a i l u r e to f u l l y i d e n t i f y a l l nongenetic sources of v a r i a t i o n . These i n c l u d e environmental e f f e c t s which were not random but were not a b l e t o be measured i n t h e context of the present study. The second p o s s i b l e cause should be c o n s i d e r e d s e r i o u s l y f o r those t r a i t s o f m a r g i n a l l y s i g n i f i c a n t h e r i t a b i l i t y . I n f u t u r e s t u d i e s , a d d i t i o n a l environmental e f f e c t s should be 52 q u a n t i f i e d to determine i f t r a i t s found t o be m a r q i n a l l y h e r i t a b l e i n t h i s study have a s i g n i f i c a n t g e n e t i c component. C h o l e s t e r o l was one serum c o n s t i t u e n t r e p o r t e d i n some previous s t u d i e s to have a l a r g e q e n e t i c component (Arave e t al.,1975, Stufflebeam and L a s l e y 1969, and T a y l o r e t a l . 1966). Furtmayr (1975) d i d not concur with t h i s f i n d i n q . In the present study, h e r i t a b i l i t y of c h o l e s t e r o l was c l o s e t o zero and, c o n s i d e r i n g the l a r g e r e l a t i v e standard e r r o r , the low estimate would not be i n d i s p u t e . Glucose was i n a s i t u a t i o n s i m i l a r t o t h a t of c h o l e s t e r o l . Rowlands e t a l . (1974), B e t t i n i e t a l . , (1975) and Furtmayr (1976) i n d i c a t e d s i g n i f i c a n t h e r i t a b i l i t y while Kitchenham and Rowlands (1976) r e p o r t e d no such s i g n i f i c n a c e . The estimate d e r i v e d frcm the present study i n d i c a t e d the h e r i t a b i l i t y t o be n e g l i g i b l e . Calcium has been r e p o r t e d to be h e r i t a b l e by t h r e e previous s t u d i e s (Kitchenham and Rowlands 1976, Rowlands e t ai»/ 1974 and B e t t i n i e t a l . 1S75). These r e p o r t s i n d i c a t e d a low h e r i t a b i l i t y f o r calcium and, i n view of the standard e r r o r s i n v o l v e d , could not be c o n s i d e r e d secure. T h i s present study was c l e a r i n i t s statement that calcium was n e g l i g i b l y h e r i t a b l e . I n o r g a n i c phosphate was not h e r i t a b l e on the b a s i s of t h i s present study. T h i s f i n d i n g was both supported and r e f u t e d i n the l i t e r a t u r e . Rowlands e t a l . (1974), i n a study using c a l v e s , r e p o r t e d a low to moderate h e r i t a b i l i t y f o r i n o r g a n i c 53 phosphate, while Kitchenham and Rowlands (1976) and H i l s c c and D i n k e l (1968) r e p o r t no s i g n i f i c a n c e . T o t a l p r o t e i n , shown s i g n i f i c a n t l y h e r i t a b l e by Kitchenham and Rowlands (1976), was not found t o be so i n the present study. U r i c a c i d was not found t o be s i g n i f i c a n t l y he.rita.ble i n t h i s study. B e t t i n i e t a l . (1975) repo r t e d a high h e r i t a b i l i t y (0.47) but no i n d i c a t i o n o f r e l i a b i l i t y was given. There was no f u r t h e r c o r r o b o r a t i o n a v a i l a b l e . The h e r i t a b i l i t y of b i l i r u b i n was estimated as negative i n t h i s study. T h i s was taken as an i n d i c a t i o n t h a t h e r i t a b i l i t y was n e g l i g i b l e . Furtmayr (1975) repo r t e d b i l i r u b i n h e r i t a b i l i t y as being i n s i g n i f i c a n t , , B e t t i n i e t a l . , ( 1 9 7 5 ) r e p o r t e d a s i g n i f i c a n t h e r i t a b i l i t y but one which was low enough to be of l i t t l e p r a c t i c a l value. H e r i t a b i l i t i e s of t r i g l y c e r i d e s , sodium, c h l o r i d e , b icarbonate and t h y r o x i n e were a l l estimated as i n s i g n i f i c a n t . Ho p u b l i c a t i o n s t o the c o n t r a r y have been l o c a t e d by t h i s author. A summary of phenotypic and environmental c o r r e l a t i o n s among a l l t r a i t s i s given i n Table V. No d i s c u s s i o n o f the agreement between the r e s u l t s o f t h i s and previous s t u d i e s w i l l be given at t h i s p o i n t . One reason i s the l a r g e number of c o r r e l a t i o n s to d i s c u s s . Another i s t h a t c o r r e l a t i o n s r e p o r t e d i n the l i t e r a t u r e are seldom of the same s t a t i s t i c a l d e r i v a t i o n T. P h e n o t y p i c (be low d i a g o n a l ) and e n v i r o n n e n t a l (above d i a g o n a l ) c o r r e l a t i o n s aaong t r a i t s » i t h a s s o c i a t e d 1 TRAIT I H i l k l F a t 1 P r o t l H i l k C F a t C P r o t C Ca P01 G l u e H=== = == +"=======«" SC=3=ES3SI1ISZI USZXSS3 3S3ZSZS Ctt 3 ex 3 3S1S ss cs ESS£=£SS*XSS 1 H i l k l . 7 5 6 1 . 0 1 9 .8661.021 . 4301 .092 . 2 0 9 1 . 100 .3561. 105 . 0 5 5 1 . 0 8 3 - . 1 1 3 1 . 0 8 8 - . 1 3 4 1 . 0 8 2 I F a t 1 1 .6981.039 . 7 5 2 1 . 0 1 7 . 2 9 7 i . 120 .1081 .091 . 3 1 2 1 . 124 . 0 7 8 1 . 0 8 6 - . 1901.091 - . 0 9 5 1 . 0 8 8 I P r o t l 1 .8761.016 .7551.032 . 3501. 120 . 2 0 8 1 . 111 . 3 9 1 1 . 120 . 0 5 9 1 . 0 9 4 - . 1 5 8 1 . 0 9 6 - . 0 7 9 1 . 0 9 5 I H i IkC I . 4111 .061 . 2 1 7 1 . 0 7 8 . 3 3 5 1 . 0 7 7 . 7 6 9 1 . 0 5 0 . 9121 .023 -.0001.101 - . 0 6 1 1 . 0 9 6 - . 1081.098 I F a t C 1 .2781.067 . 1 5 9 1 . 0 6 0 . 2 9 2 1 . 0 7 3 . 7 8 9 1 . 0 2 9 . 7 8 5 1 . 0 1 5 . 1 0 4 1 . 0 9 2 - . 0 8 1 1 . 0 9 0 - . 1 4 7 1 . 0 8 7 I P r o t C 1 . 1 0 9 1 . 0 6 6 . 3 1 1 1 . 0 7 7 . 1 2 8 1 . 0 7 2 . 9231 .012 . 8 3 2 1 . 0 2 3 . 0 4 5 1 . 1 1 5 - . 0 5 9 1 . 1 0 2 - . 0 7 1 1 . 1 2 5 I Ca 1 . 0 5 0 1 . 0 6 2 . 0 6 9 1 . 0 6 3 . 0 5 2 1 . 0 6 8 -.0001.066 . 0 8 3 1 . 0 6 3 .0321.071 . 0 0 8 1 . 0 6 5 . 1031.062 I POI 1 - . 0 9 7 1 . 0 6 5 - . 1 2 9 1 . 0 6 6 - . 1381.068 - . 0 5 2 1 . 0 6 6 - . 0 7 4 1 . 0 6 1 - . 0 5 2 1 . 0 6 9 . 0 0 8 1 . 0 5 2 - . 1051.065 I G l u e 1 -.1221.061 - . 0 8 3 1 . 0 6 4 - . 0 6 9 1 . 0 6 8 - . 0 9 8 1 . 0 6 6 - . 1 1 3 1 . 0 6 2 - . 0 6 2 1 . 0 7 5 . 1 0 1 1 . 0 4 9 - . 1 0 2 1 . 0 5 1 I BOB I . 0 5 6 1 . 0 6 5 . 0 8 2 1 . 0 6 6 . 0 1 1 1 . 0 7 5 . 0611 .068 . 1201.065 . 0 6 2 1 . 0 7 7 . 0 4 8 1 . 0 5 2 .1131 .054 - . 0 4 2 1 . 0 5 2 I O r i c 1 . 0 8 3 1 . 0 6 7 . 0 3 7 1 . 0 6 5 . 0 4 2 1 . 0 7 1 . 0301 .067 . 0 1 9 1 . 0 6 2 . 0951 .070 . 1691.049 . 1841.050 . 1 0 9 1 . 0 5 0 C h o l 1 . 0 1 6 1 . 0 6 2 - . 0 1 1 1 . 0 6 1 - . 0 1 2 1 . 0 6 8 . 2751.063 .2201.061 • 2 1 7 t . 0 6 9 . 1 3 3 1 . 0 1 8 - . 0 9 6 1 . 0 5 1 - . 0 0 7 1 . 0 4 9 i T P I - . 0 1 9 1 . 0 6 8 - . 0 1 4 1 . 0 7 0 - . 0 5 1 1 . 0 7 1 . 0 1 5 1 . 0 6 1 - . 0 1 6 1 . 0 6 2 . 0 1 9 1 . 0 6 8 . 1 9 5 1 . 0 1 8 - . 0 5 6 1 . 0 5 2 - . 0 1 5 1 . 0 5 0 A l b I . 0 9 8 1 . 0 6 5 . 0 3 7 1 . 0 6 9 . 0 5 2 1 . 0 7 6 . 0 3 5 1 . 0 7 2 . 1321.066 . 1011.078 . 3 6 1 1 . 0 4 7 - . 0 7 3 1 . 0 5 6 . 0 3 3 1 . 0 5 3 B i l i 1 - . 3621.051 -.0121.061 - . 1091.067 .0001.066 .0111.061 - . 0 1 9 1 . 072 . 0 1 6 1 . 0 4 9 .0631 .052 . 3 0 1 1 . 0 4 5 A l k P I - . 0 1 9 1 . 0 7 1 - . 0 7 2 1 . 0 7 6 - . 0 0 6 1 . 0 8 2 - . 1951.080 -.2111.074 -.2021.086 . 0 2 7 1 . 0 6 2 .0581 .064 . 0 7 2 1 . 0 6 2 SCOT 1 . 0191.061 - . 0 0 1 1 . 0 6 1 . 0 8 7 1 . 0 6 6 . 0 6 7 1 . 0 7 0 . 0 1 3 1 . 0 6 8 . 0 1 3 1 . 0 7 3 - . 0 1 8 1 . 0 5 3 .0781 .054 . 0 0 3 1 . 0 5 2 C r e a t I - . 0 9 3 1 . 0 7 1 - . 1 1 2 1 . 0 7 7 - . 0 5 5 1 . 0 8 5 - . 0 2 3 1 . 0 8 7 - . 1321.081 - . 1 1 9 1 . 0 9 5 . 0 0 6 1 . 0 6 3 . 1021.066 . 0 3 0 1 . 0 6 2 T r i q I - . 1 6 7 1 . 0 6 0 - . 1 3 3 1 . 0 6 3 - . 1 6 9 1 . 0 6 7 - . 1021.065 - . 0 8 0 1 . 0 6 3 - . 1 1 6 1 . 0 7 2 . 2 8 3 1 . 0 4 5 . 0481 .053 . 1 4 7 1 . 0 4 8 Na 1 - . 0391.062 - . 0391.061 .0021.069 . 0 5 5 1 . 0 6 5 . 0 5 8 1 . 0 6 2 .0161.071 . 0 6 7 1 . 0 1 9 .1341 .052 - . 0 7 6 1 . 0 5 1 K . 1 1 3 1 . 0 6 8 - . 0 0 8 1 . 0 7 1 . 0 1 3 1 . 0 7 6 . 0 2 9 1 . 0 7 1 . 0 5 8 1 . 0 6 9 . 1 0 2 1 . 0 7 8 .1291 .056 .3751.051 - . 0 3 2 1 . 1 0 0 C l . 0 0 8 1 . 0 6 3 . 0101 .061 . 0 1 3 1 . 0 6 9 - . 0691 .067 - . 0 6 3 1 . 0 6 5 - . 0 7 0 1 . 0 7 2 .0001.052 - . 1 9 9 1 . 0 5 1 . 1001.051 HC03 - . 0 9 3 1 . 0 6 1 -.0381.066 - . 0 5 6 1 . 0 6 9 - . 0 3 0 1 . 0 6 6 - . 0 1 6 1 . 0 6 3 - . 0 2 3 1 . 0 7 2 - . 0 1 7 1 . 0 1 9 .2121.051 - . 0 3 1 1 . 0 5 1 T4 - . 0 1 9 1 . 0 6 1 .0201.063 .0001.068 - . 0 1 1 1 . 0 6 5 - . 0 2 9 1 . 0 6 3 - . 0 9 9 1 . 0 7 1 . 1201.043 - . 0 6 9 1 . 0 5 1 . 1631.048 A n y l - . 0 1 9 t . 07<t -.0131.080 - . 0 2 6 1 . 0 8 3 . 0 6 1 1 . 0 7 5 . 0151 .073 .0121.079 . 1201.058 - . 0 9 1 1 . 0 6 2 . 1 5 4 1 . 0 5 8 Table V<cont.). Phenotypic (belov diagonal) and environmental (above diagonal) c o r r e l a t i o n s among t r a i t s with associated SE. i r TBAIT BON Oric Choi T P ——————34 ============== ==SSSSS3BSS3 33333333 —  — ——— • 3 3 ISSSS3tK H i l k l -.029±.090 -.0991.095 .0181.084 .0221.095 Fat 1 .0341.093 -.0491.094 -.0161.089 .0371.100 P r o t l -.0781.111 -. 1611. 110 -.0141.096 . 0591. 107 flilkC .056*.100 -.0371.104 .3641.096 -.0191.094 Pat c .123±.092 .0521.090 .2741.088 -.0191.088 Protc .0411.119 .1011. 114 .3401.110 .0531. 103 Ca .050±.066 . 1731.062 .1341.060 . 1991.061 P04 .1191.069 .1891.063 -.0991.065 -.0581.065 Glue -.0441.066 .1111.062 -.0071.062 -. 0451.062 BOH .1871.064 . 1891.064 -. 1371.065 Oric . 18U1.050 .0311.061 -. 0521.063 Choi .1811.050 .0311.049 .0601.063 T P -.1301.051 -.0511.050 .0591.050 Alb .0801.056 -.0691.054 .2651.051 .0031.054 B i l i . 1921.050 .4281.040 -.0971.049 -. 1761.049 Alk P -. 0231.061* .0111.061' -.0971.061 -. 1021.061 SGOT .0371.054 .0081.052 .0411.052 -. 0541. 053 creat -.0661.064 -.0371.061 -.0011.063 -. 0411.061 T r i g -.0031.053 .0661.051 .0901.049 . 1011.050 Na .0041.053 .0531.051 .0371.050 -. 1271.050 K . 1221.058 .1701. 054 .0331.056 . 0681.056 C l | -.0921.053 -.0261.052 -.0751.052 -.0651.051 HC03 I -.0041.053 .0551.050 -.0101.050 -. 1551. 049 T4 | .0121.052 -.0181.050 .0501.049 -. 0541.050 Amyl | -.0261.062 .0301.061 .0931.058 . 0831.059 Alb B i l i Alk P SGOT Creat 3S333SCSISS3 3333 3=3 33 3 33 3 2333333333 33 3S3E3 3333 33 .0381.090 - . 3 9 5 1 .071 .1241.114 .02 81.082 -.0031.112 -.0221.096 -.0481.088 .0521.117 -.0021.089 .0311.122 .0881.110 -. 1231.093 .1911.128 .1021.092 .0951.140 -.1401.115 -.0001.102 .1161.159 .0671.105 . 1071.148 .0391.098 .0551.092 .0111.138 -.0011.099 .0061.136 -.0231.126 -.0271.115 .1211.178 .0761.110 .1751.198 .3861.060 .0161.061 .0341.089 -.0511.067 .0081.093 -.0801.074 .0651.066 .0611.094 .0861.070 . 1221.099 .0351.069 .3031.056 .0911.089 .0031.067 .0381.091 -.0111.075 .2001. 063 -.0211.091 .0391.070 -.0511.093 -.0761.069 .4321.050 .0121.086 .0091.067 -.0411.090 .2861.065 -.0981.061 -.1221.089 .0431.067 -.0021.093 .0031.070 -.1791.062 -.1151.086 -.0571.067 -.0561.090 -.0371.070 -.0641.095 -.0901.076 .2181.103 -.0341.054 -.0111.089 .0071.067 .0001.093 -.0641.066 -.0091.062 .27«t. 104 .005±.127 -.0201.057 .0071.053 .0871.069 -.0091.098 .1191.070 .0001.063 .1051.079 .0311.067 . 1751.053 .0521.049 .1611.061 .0241.053 -.4411.056 . 1571.054 .0651. 062 .0041.062 .1201.054 .1191.063 .0591.061 •034t.055 -.0841.068 .0341.060 .1051.073 . 1281.054 .0221.052 .0391.062 .0601.054 .0681.061 -. 1301.054 ,0791. 049 -.0231.062 -.0041.054 -.0071.063 .2581.050 -.0341. 049 .0861.061 .0041.052 .0261.062 . 1461.063 . 0371. 059 -.0091.075 .0291.063 .0631.079 Table V(cont . ) . Phenotypic (belov diagonal) and environmental (above diagonal) c o r r e l a t i o n s aiong t r a i t s » i t h assoc iated SE. i r TRAIT 1 T r i g Na K C l HC03 T4 Amyl ^ — — — — — — — ——se.— — — 33SCSSSE3S2S3 3ZXX3S ————=——-——-— 3isss:s3:z3=x XSS3SZXXX333X ———————————— Bi lJM 1 -.1861.081 -.0431.084 -.0051.099 . 0091.085 -.1391.087 -.0211.082 .0691.108 Fat 1 I -.1521.086 -.0451.089 .0041.101 .0121.089 -.0471.091 .0231.036 . 1431. 127 P r o t l 1 -.1961.095 .0021.097 -.1181.112 .0491.097 -.0641.097 .0001.094 .1291.130 Hi lkC 1 -.1371.100 .0711.096 -.1161.114 .0261.101 -.0401.100 -.0541.097 -.0131.114 Fat C I -.1011.091 .0701.088 .0431.098 -.0871.096 -.0201.090 -.0361.090 .0081.106 Protc I -.1661.118 .0611.111 .0091.123 . 1091.118 -.0311.115 - .138i.114 .0371.123 Ca I .2831.056 .0671.062 .1421.073 - . 0001.066 -.0471.062 .1201.060 . 1391.079 P04 1 .0491.067 .1381.066 .4121.066 - . 2061.065 .2191.064 -.0711.065 - . 1081.086 Glue 1 .1481.060 -.0781.064 -.0401.051 . 1041.065 -.0321.064 . 1641.060 .1781.073 BOH 1 -.0031.068 .0041.068 .1881.077 -.0961.067 -.0041.068 .0131.066 . 1051.087 Or i c 1 .0681.064 .0541.064 .1761.070 -.0261.065 .0551.063 -.0191.063 .0501.084 Choi I .0901.061 .0371.062 .0361.074 - . 0771.066 -.0101.062 .0501.061 . 1071.078 T P 1 .1041.064 -.1281.062 .0761.074 -.0661.065 -.1571.062 -.0551.063 .0881.079 Alb 1 .1901.068 .1701.070 -.0251.083 . 1391.070 -.1401.070 .2771.064 . 1691.085 B i l i I .0521.061 .0651.062 .0371.073 .0221.066 .0791.062 -.0341. 061 .0431.080 Alk P I .2031.088 .0041.088 .0361.102 . 0411.087 -.0281.088 .1091.089 .123*.115 SGOT 1 .0251.068 .1281.069 -.0601.080 .0641.070 -.0041.069 .0041.067 -.1151.088 Creat I -.5761.086 .1551.093 .2451.111 .0741.090 -.0091.093 .0341.092 - . 1351. 131 T r i g -.0481.062 .0541.074 -.1381.064 -.0531.062 .1001. 060 . 1721.084 Ha 1 -.0481.049 .2421.071 . 2561.061 .2881.056 .0051.061 -.0421.082 K I .0491.056 .2171.054 . 0501.074 -.0061.074 -.0571. 073 -.0211.093 C l 1 -.1341.051 .2491.048 .0481.056 -.3511.057 .0031.065 . 1241.082 HC03 I -.0531.049 .2881.045 -.0051.056 - . 3411.045 -.0421.061 - . 1641.081 T4 I .1001.048 .0051.049 -.0521.056 .0021.051 -.0421.049 .-971.080 Aayl 1 . 1421.060 -.0361.060 .0311.066 .1141.059 -.1401.059 .0831. 058. 57 nor were the data adjusted f o r the same e f f e c t s as i s done i n the present study. A d i s c u s s i o n of c e r t a i n r e l a t i o n s h i p s w i l l be undertaken i n a l a t e r s e c t i o n . A summary of g e n e t i c components of co v a r i a n c e and ge n e t i c c o r r e l a t i o n i s given i n Table V I . I t i s noted t h a t many cov a r i a n c e components and many g e n e t i c c o r r e l a t i o n s were s e t to ze r o . T h i s was done f o r the same reason that h e r i t a b i l i t i e s of some t r a i t s were set to zero. I f the g e n e t i c component of va r i a n c e f o r the i n d i v i d u a l t r a i t was negat i v e , t h i s was considered as a s t a t i s t i c a l e s t i m a t i o n o f a parameter t h a t has a lower l i m i t o f z e r o . The o b t a i n i n g o f a n e g a t i v e value was t r e a t e d as a s t a t i s t i c a l i n d i c a t i o n t h a t there was no g e n e t i c component of v a r i a n c e . The same r a t i o n a l e could be a p p r o p r i a t e f o r some g e n e t i c components of v a r i a n c e that were only s l i g h t l y g r e a t e r than zero. I f a negative or a very low g e n e t i c component of v a r i a n c e was used t o estimate g e n e t i c c o r r e l a t i o n s , the estimate of these g e n e t i c c o r r e l a t i o n s were s u b j e c t t o extreme f l u c t u a t i o n , the exact value o f which may g r e a t l y exceed the t h e o r e t i c a l l i m i t s o f the c o r r e l a t i o n s t a t i s t i c . Cue to chance, c o r r e l a t i o n s generated f o r these t r a i t s may f a l l i n the acc e p t a b l e range, but l a r g e standard e r r o r s were i n d i c a t i v e of the l a c k of c r e d i b i l i t y a ttached t o c o r r e l a t i o n s between two t r a i t s with extremely low g e n e t i c components of v a r i a n c e . On a t h e o r e t i c a l b a s i s i t can be seen t h a t i f a t r a i t has no g e n e t i c component, then i t cannot e x h i b i t a g e n e t i c T a b l e VI. G e n e t i c c o r r e l a t i o n s (below d i a g o n a l ) and g e n e t i c c o u p o n e n t s o f c o v a r i a n c e (above d i a g o n a l ) w i t h a s s o c i a t e d SE. TRAIT 1 H i l k l F a t 1 P r o t l M i l k C Fat C P r o t C Ca P04 G ====== U = = =r = = = = = = = = = = ============= ============== ============== ============ = = = X = S3S ESEX ============== ====. t l i l k l 102111822 268512710 9. 67E » l 6 .80E 386612206 102612600 0. 0 0.0 0.0 F a t 1 I .3141.493 110.198.5 917. ±1110 199.1125. 131. 185.5 0.0 0.0 0.0 P r o t l I .9411.101 . 7 7 8 1.215 2197±1762 153 . 188.8 139. 185. 2 0. 0 0.0 0.0 U i l k C I . 5881.371 . 1 0 7 i . 393 .3021.389 1 . 3 8 E 1.75B 1.16E1. 82E 0. 0 0. 0 0.0 F a t C I . 6801. 130 .6521. 283 .6131.371 . 8391.101 516. 1290. 0.0 0.0 0. 0 P r o t C 1 .7011. 358 . 1371. 339 . 5 5 7 1.298 .9191.035 .9661.053 0.0 0. 0 0.0 Ca 1 0.0 0.0 0.0 0. 0 0.0 0. 0 0.0 0.0 P04 1 0.0 0. 0 0.0 0.0 0.0 0. 0 0.0 0. 0 G l u e I 0.0 0. 0 0.0 0.0 0.0 0. 0 0. 0 0.0 BOS . 9411.797 .1911. 652 . 7 6 8 1.561 . 1311.589 .1581.610 . 1581. 448 0.0 0.0 0.0 D r i c 1 0.0 1. 71 i 1 . 6 7 1.81i1. 12 O.C 0.0 0. 0 0.0 0.0 0.0 C h c l 0.0 0. 0 0.0 0.0 0.0 0. 0 0. 0 0.0 0.0 T P -. 5971.602 -.537t. 516 - . 7 9 9 1.601 0.0 0.0 0. 0 0. 0 0.0 0.0 A l b .637i.661 . 456t. 583 -.1381.519 .8961.513 .6971.484 .5601. 393 0.0 0. 0 0.0 B i l i 0.0 0. 0 0.0 0. 0 0.0 0. 0 0. 0 0.0 0.0 A l k P -.9611.505 -. 5701. 396 - . 9061.192 -. 9051.190 -.9111.193 - . 8 6 8 1.203 0.0 0.0 0.0 SGOT 0.0 0. 0 0.0 .1001.508 .1071.532 -. 1211.619 0.0 0.0 0.0 C r e a t 1 -.1901.132 - . 6 3 6 1 . 357 -.5161.397 -. 2801.297 - . 4 4 8 1.281 -.5911.244 0. 0 .0671.712 0.0 T r i g O.C 0. 0 0.0 0.0 0.0 0. 0 0. 0 0.0 0.0 Na 0.0 0. 0 0.0 0.0 0.0 0.0 0. 0 0.0 0.0 K . 9831. 530 -.078t.525 . 8 3 6 1.597 .6161.391 .1371.150 .4441. 399 0. 0 0.0 0.0 C I 0.0 0. 0 0.0 - . 8661.990 0.0 0.0 0.0 0.0 0.0 HC03 0.0 0. 0 0.0 0.0 0.0 0. 0 0. 0 0.0 0.0 TU 0.0 0. 0 0.0 0.0 0.0 0. 0 0.0 0.0 0.0 A a y l -. 195±. 526 -. 7321. 368 -.6531.451 . 3281.368 .0391.103 . 0691. 432 0. 0 0.0 0.0 00 I I -'E'xIO* f o r c o v a r i a n c e and SE. Table V I ( c o n t . ) . Genetic c o r r e l a t i o n s (below diaqonal) and qenetic components of co variance (above diaqonal) with associated SE. •— i TB AIT BUN Oric Chol T P Alb B i l i Alk P SGOT Creat .3^3 33=3:3= = ES ssxs E SS3333EE3=33 ESSE S3 SSXSXS ============== ============= ========= =============== ============== ========== H i l k l na.±73.7 0.0 0.0 -26.3H1.2 13. 9t6.71 0.0 -252211013 0.0 -7.6913. 42 Fat 1 4.3912.12 1.021.128 0.0 -1. 151.479 .4961.209 0.0 -75.5131.8 0.0 -.4631.199 P r o t l 7.52±3.16 1.221.503 0.0 -1.331.569 -.1581.051 0.0 -92.7137.1 0.0 -.3541.150 HilkC 52.H30.8 0.0 0.0 0.0 47. 0H8.8 0. 0 -615312523 451.1290. -11 . 7 H . 47 Fat C 2.18±1.73 0.0 0.0 0.0 1.291.589 0.0 -220.193.5 17.3t7.31 -.6621.279 ProtC I 3.0H1.56 0.0 0.0 0.0 1.231.539 0. 0 -207.188.9 -15.311.69 -.8901.369 Ca [ 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 P04 I 0.0 0.0 0.0 0.0 0.0 0. 0 0.0 0.0 .0011.001 Glue I 0.0 0.0 0.0 0.0 0.0 0. 0 0.0 0.0 0.0 BOH 0.0 0.0 0.0 .0611.026 0.0 -.2981.178 0.0 -.0061.003 U r i c I 0.0 0.0 0.0 0.0 0. 0 0.0 0.0 0.0 Chol I 0.0 0.0 0.0 0.0 0. 0 0.0 0.0 0.0 T P 1 0.0 0.0 0.0 0.0 0. 0 0.0 0.0 0.0 l i b I 1.45H.09 0.0 0.0 0.0 0.0 -.0721.047 .4181.117 -.0011.000 B i l i I 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Alk P I -.0U81.585 0. 0 0.0 0.0 -.0841.468 0.0 -65.3122.1 .2081.087 SGOT I 0.0 0.0 0.0 0.0 .9191.955 0.0 -1.011.660 .0951.039 Creat | -.2111.598 0.0 0.0 0.0 -.2601.116 0.0 .3151.299 .2661.510 T r i q I 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Na | 0.0 0.0 0.0 0.0 0.0 0. 0 0.0 0.0 0.0 K | -. 7011.998 0.0 0.0 0.0 .7571.546 0.0 -.6571.391 1. 101.793 -.4011.400 CI I 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 HC03 I 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 T4 I 0.0 0. 0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Auyl I -1.29t. 944 0.0 0.0 0.0 .0081.516 0. 0 -.4161.346 1.16H.03 .5941.283 U3 Table ?I(cont.). Genetic c o r r e l a t i o n s (belov diagonal) and qenetic components of covariance (above diaqonal) with associated SE. i r • I TBAIT I T r i g Ha C l HC03 T4 Anyl | H*"====4 S BXSSSXSZSSSC3SS X2S3CZXXEEZS nm s x z s xs xes xzxzzss xcxt — — — — mi 1 H i l k l | 0.0 0.0 • 34.0*15.0 0.0 0.0 0.0 -4426*1770 I I Fat 1 | 0.0 0.0 -.130*.055 0.0 0.0 0.0 -354.*142. I 1 P r o t l | 0.0 0.0 1.07*.l»36 0.0 0.0 0.0 -252.±104. | 1 BilkC | 0.0 0.0 07.8*18.5 -234.496.6 0.0 0.0 6438*2710 | I Fat C | 0.0 0. 0 .367*.191 0.0 0.0 0.0 27.8*13.4 | J Protc | 0.0 0.0 1.24*.565 0.0 0.0 0.0 41.9*24.5 I I Ca | 0.0 0.0 0.0 0.0 0.0 0.0 0.0 I I POtt | 0.0 0.0 0.0 0.0 0.0 0.0 Q.O | I Glue | 0.0 0.0 0.0 0.0 0.0 0.0 0.0 I 1 BOH | 0.0 0.0 -.043*.012 0.0 0.0 0.0 -22.6*8.60 I 1 Ur i c | 0.0 0. 0 0.0 0.0 0.0 0.0 0.0 I 1 Choi | 0.0 0.0 0.0 0.0 0.0 0.0 0.0 I 1 T P 1 0.0 0. 0 0.0 0.0 0.0 0.0 0.0 1 1 Alb 1 0.0 0.0 .007*.003 0.0 0.0 0.0 .023*.225 I 1 B i l i | 0.0 0.0 0.0 0.0 0.0 0.0 0.0 | 1 Alk P | 0.0 0.0 -.715*.292 0.0 0.0 0.0 -150.*56.4 ( 1 SGOT | 0.0 0.0 .723*.281 0.0 0.0 0.0 234.±89.5 | I Creat | 0.0 0.0 -.002*.001 0.0 0.0 0.0 1.20*.466 | I T r i g I 0. 0 0.0 0.0 0.0 0.0 0.0 | 1 Ha | 0.0 0.0 0.0 0.0 0.0 0.0 1 1 K 1 0.0 0. 0 0.0 0.0 0.0 1.21*. 487 | 1 C l | 0.0 0.0 0.0 0.0 0.0 0.0 1 I HC03 | 0.0 0. 0 0.0 0.0 0.0 0.0 I |T<* I 0.0 0. 0 0.0 0.0 0.0 0.0 I 1 A i y l | 0.0 0. 0 .317*.453 0.0 0. 0 0. 0 1 X. i 61 c o r r e l a t i o n with another t r a i t , r e g a r d l e s s of whether the second t r a i t has a genetic component. For t h i s reason, when the above s i t u a t i o n occurred o r was i n d i c a t e d by extreme c o r r e l a t i o n s and standard e r r o r s , the g e n e t i c component of c o v a r i a n c e and the ge n e t i c c o r r e l a t i o n were s e t t o zero. The appendix l i s t s the number of p a i r e d o b s e r v a t i o n s used f o r each c o r r e l a t i o n . G e netic improvement i n d a i r y c a t t l e has proceeded p r i m a r i l y by s e l e c t i o n f o r the a d d i t i v e p o r t i o n o f the t o t a l gene e f f e c t , and i t i s u n l i k e l y t h a t the d a i r y farmer w i l l f i n d a b e t t e r breeding program w i t h i n the range o f c o n v e n t i o n a l s e l e c t i o n t h e o r y . To work w i t h i n the framework of d i r e c t s e l e c t i o n , the t r a i t s must have a s i g n i f i c a n t g e n e t i c component. In g e n e r a l , a s i g n i f i c a n t g e n e t i c component i n d i c a t e s that s e l e c t i o n on th a t t r a i t can r e s u l t i n movement of the p o p u l a t i o n mean i n t h e d e s i r e d d i r e c t i o n . In the context o f t h i s present study, i t a l s o i n d i c a t e d t h a t a p o r t i o n of the genotype of the cow was r e s p o n s i b l e f o r e s t a b l i s h i n g t h e measured l e v e l o f t h a t t r a i t , and t h a t the a d d i t i v e e f f e c t of the genes were a major c o n t r o l l i n g f a c t o r i n t h i s genotype. A l s o , with regards t o c o n v e n t i o n a l s e l e c t i o n t h e o r y , another approach i s t h a t of i n d i r e c t s e l e c t i o n . T h i s approach i s based on the premise t h a t t h e t r a i t s i n v o l v e d have a s i g n i f i c a n t genetic c o r r e l a t i o n and thus s e l e c t i o n f o r one t r a i t w i l l r e s u l t i n a con c u r r e n t change i n another t r a i t . The c l a s s i c a l i n t e r p r e t a t i o n o f t h i s s i t u a t i o n i s that the 62 i n d i v i d u a l genotypes i n v o l v e d with the t r a i t s have some p o r t i o n i n common, the r e l a t i v e s i z e of t h i s p o r t i o n being estimated by the g e n e t i c c o r r e l a t i o n . T h i s common genotype a f f e c t s the two t r a i t s through the phenomenon of p l e i o t r o p y of gene e f f e c t . , The i d e a o f g e n e t i c c o r r e l a t i o n i s t h a t there must be s i g n i f i c a n t g e n e t i c components f o r both t r a i t s . I f a t r a i t were shown to have no g e n e t i c component, then i t f o l l o w s t h a t i t cannot have any s i g n i f i c a n t g e n e t i c c o r r e l a t i o n s . On t h i s b a s i s , the number o f t r a i t s m e r i t i n g f u r t h e r d i s c u s s i o n i s reduced t o those with a s i g n i f i c a n t g e n e t i c component. These are c r e a t i n i n e , a l k a l i n e phosphatase, amylase, potassium, albumin, SGOT, BON and a l l milk production t r a i t s . , In f u r t h e r d i s c u s s i o n of the v a r i o u s c o r r e l a t i o n s only these t r a i t s w i l l g e n e r a l l y be c o n s i d e r e d . Beyond the e s t i m a t i o n of h e r i t a b i l i t y of the serum t r a i t s , t h i s study a l s o examined some r e l a t i o n s h i p s i n v o l v i n g these t r a i t s and the milk production t r a i t s . 1 summary of phenotypic and g e n e t i c c o r r e l a t i o n s between the production t r a i t s and the h e r i t a b l e serum c o n s t i t u e n t s i s given i n Table VII. The g e n e t i c c o r r e l a t i o n s were o f g r e a t e s t i n t e r e s t i n t h i s study but a word of c a u t i o n i n i n t e r p r e t i n g these c o r r e l a t i o n s i s warranted. The g e n e t i c c o r r e l a t i o n s were c a l c u l a t e d using h a l f s i b a n a l y ses and m u l t i p l i c a t i o n by a constant of f o u r was i n v o l v e d i n the c a l c u l a t i o n . S i n c e e r r o r s of measurement were a l s o m u l t i p l i e d by t h i s f a c t o r , the standard e r r o r a s s o c i a t e d Table VII. Genetic (above) and phenotypic (below) c o r r e l a t i o n s between s e l e c t e d serum c o n s t i t u e n t s and the production t r a i t s . 1 T , — r I T r a i t | 1-=======+ h* | Creat Alk P Atayl K Alb SGOT BON | 1 flilkl | .10741.0976 | -.4901.432 -.0934.074 -.9641.505 -.0491.074 -.4951.526 -.0191.074 .9831.530 .1181.068 .6371.661 .0981.065 0. 0 .0191.061 .9441.797 | .0561.065 | 1 Fat 1 | .1530±.1O78 | -.636±.357 -.1121.077 -.5701.396 -.0721.076 -.7321.368 -.0431.080 -.0781.525 -.0081.071 .4561.583 .0371.069 Q.O -.0011.064 .4941.652 | .0821.066 | I P r o t l | .15541.1172 | -.546l.397 -.0551.085 -.9C6t.492 -.0061.082 -.6531.451 -.0261.083 .8361.597 .0131.076 -. 1381. 549 .0521.076 0. 0 .0871.066 .7681.564 | .0411.075 | I Milkc | .3370±.1382 | -.2801.297 -.0231.087 -.905l.190 -.1951.080 .328l.368 .0641.075 .6161.394 .0291.074 .896l.513 .0351. 072 .1001.508 .0671.070 .1341.589 I .0611.068 | I Fat C | .28211.1270 | -.4481.281 -.1321.081 -.911t.193 -.2441.074 .0391.403 .0151.073 .1371.4 50 .0581.069 .6971.484 .1321.066 .1071.532 .0131.068 .1581.610 I .1201.065 1 I ProtC | ,3979t.1560 | -.5911.244 -.1191.095 - .8681.203 - .2021.086 .C691.432 .0421.079 . 4441 .399 . 1021. 078 .5601.393 .1011.078 -. 1211.619 .0431.073 .1581.448 | .0621.077 | 64 with the g e n e t i c c o r r e l a t i o n was a p p r o p r i a t e l y i n f l a t e d . The standard e r r o r s must be l a r g e f o r these c o r r e l a t i o n s s i n c e they were estimated from s e v e r a l s t a t i s t i c s , each one s u b j e c t to i t s own sampling v a r i a n c e . , The magnitude of the c o r r e l a t i o n i s best judged i n r e l a t i o n t o i t s standard e r r o r . F i r s t l a c t a t i o n milk p r o d u c t i o n possessed s t r o n g g e n e t i c c o r r e l a t i o n s with c r e a t i n i n e (-0.490), a l k a l i n e phosphatase (-0,964), potassium (0.983), albumin (0.637) and BUN (0.944). The r e l i a b i l i t y of these c o r r e l a t i o n s was r e f l e c t e d i n t h e i r standard e r r o r s . The s t r o n g e s t genetic c o r r e l a t i o n was between milk and a l k a l i n e phosphatase, with the standard e r r o r i n d i c a t i n g a r e l i a b l e e s t i m a t e . The poorest c o r r e l a t i o n among the set of c o n s t i t u e n t s l i s t e d above was f o r albumin. Although the c o r r e l a t i o n between c r e a t i n i n e and milk was l e s s than t h a t f o r albumin, the standard e r r o r was much lower, i n d i c a t i n g a more r e l i a b l e estimate. Current l a c t a t i o n milk was c o r r e l a t e d with a s m a l l e r subset of serum c o n s t i t u e n t s . A l k a l i n e phosphatase, as with f i r s t l a c t a t i o n s i l k , showed the s t r o n g e s t r e l a t i o n s h i p (r=-C.905) with a s m a l l standard e r r o r . / Potassium (0.616) and albumin (0.896) a l s o had s t r o n g , r e l i a b l e c o r r e l a t i o n s with c u r r e n t l a c t a t i o n milk. U n l i k e f i r s t l a c t a t i o n milk, t h e r e was no stro n g r e l a t i o n s h i p with c r e a t i n i n e or BUN. These d i s c r e p a n c i e s between what are e s s e n t i a l l y e s t i m a t e s of the same c o r r e l a t i o n taken at d i f f e r e n t p o i n t s i n time were not s e r i o u s . The c o r r e l a t i o n e stimates f o r c r e a t i n i n e and BUN were a s s o c i a t e d 65 w i t h l a r g e s t a n d a r d e r r o r s . The f a c t t h a t t h e y a p p e a r e d s i g n i f i c a n t o n l y f o r t h e f i r s t l a c t a t i o n may h a v e i n d i c a t e d t h a t t h e c o r r e l a t i o n i m p o r t a n c e was m a r g i n a l a n d t h e two e s t i m a t e s o f t h e c o r r e l a t i o n were d i f f e r e n t m e r e l y by c h a n c e . L i t e r a t u r e was s p a r s e i n r e p o r t i n g o f r e l a t i o n s h i p s o f se r u m c c n s t i t i u e n t s w i t h m i l k p r o d u c t i o n . K i t c h e n h a m e t a l . (1975) and Pa y n e e t a l . (1973) r e p o r t e d a r e l a t i o n s h i p b e t w e e n m i l k p r o d u c t i o n and a l b u m i n , i n a g r e e m e n t w i t h t h i s p r e s e n t s t u d y . F u r t m a y r (1975) r e p o r t e d a p o s i t i v e c o r r e l a t i o n w i t h SGOT, a f i n d i n g n o t s u p p o r t e d by t h i s p r e s e n t s t u d y . O t h e r c o r r e l a t i o n s b e t w e e n serum c o n s t i t u e n t s and m i l k p r o d u c t i o n e s t i m a t e d i n t h i s s t u d y were n o t d i s c u s s e d o r were n o t e d t o be i n s i g n i f i c a n t i n t h e l i t e r a t u r e , F i r s t l a c t a t i o n f a t p r o d u c t i o n was g e n e t i c a l l y c o r r e l a t e d w i t h c r e a t i n i n e (-0,636), a l k a l i n e p h o s p h a t a s e (-0.570) a n d a m y l a s e (-0.732). C u r r e n t f a t p r o d u c t i o n f o l l o w e d a s i m i l a r p a t t e r n e x c e p t t h a t a m y l a s e was n o t s t r o n g l y c o r r e l a t e d . A l s o , a l b u m i n a p p e a r e d a s h i g h l y c o r r e l a t e d (0.697) f o r c u r r e n t f a t o n l y . F i r s t l a c t a t i o n p r o t e i n y i e l d was c o r r e l a t e d w i t h c r e a t i n i n e (-0.546), a l k a l i n e p h o s p h a t a s e (-0.906), a m y l a s e (-0.653), p o t a s s i u m (0.836) a n d BON (0.768) . C u r r e n t p r o d u c t i o n was c o r r e l a t e d w i t h a s m a l l e r g r o u p o f c o n s t i t u e n t s . T h i s g r o u p c o n s i s t e d o f c r e a t i n i n e (-0.591), a l k a l i n e p h o s p h a t a s e (-0.868), 66 potassium (0.444) and albumin (0.560). There i s some d i s c u s s i o n warranted on the r e l a t i v e merits o f the two groups o f c o r r e l a t i o n s , those i n v o l v i n g f i r s t l a c t a t i o n p r o duction and those i n v o l v i n g c u r r e n t l a c t a t i o n . C urrent l a c t a t i o n records r e p r e s e n t e d estimates t h a t were i n d i c a t i v e o f the p o p u l a t i o n as i t e x i s t e d a t the time of b l e e d i n g . T h i s a s s o c i a t i o n i n time between c u r r e n t l a c t a t i o n t r a i t s and serum t r a i t s was important i n t h a t these r e l a t i o n s h i p s were r e f l e c t i o n s of c u r r e n t p h y s i o l o g i c a l events. Thus, i f c u r r e n t f e e d i n g programs were a cause of a serum and p r o d u c t i o n change, c o r r e l a t i o n s w i l l tend to be overestimated. T h i s o v e r e s t i m a t i o n , however, should be present only i n environmental and phenotypic c o r r e l a t i o n s . Genetic c o r r e l a t i o n s would be expected to be u n a f f e c t e d by such e n v i r o n m e n t a l l y caused r e l a t i o n s h i p s . Beyond t h i s , the comparison of f i r s t l a c t a t i o n versus c u r r e n t l a c t a t i o n c o r r e l a t i o n s were s u b j e c t to the same c o n s i d e r a t i o n s as were d i s c u s s e d with r e s p e c t t o h e r i t a b i l i t i e s . On balance, then, f i r s t l a c t a t i o n c o r r e l a t i o n s with serum t r a i t s may be more r e l i a b l e i n d i c a t o r s of u n d e r l y i n g g e n e t i c r e l a t i o n s h i p s f o r the f o l l o w i n g reasons. F i r s t l a c t a t i o n c o r r e l a t i o n e s t i m a t e s were c o n s e r v a t i v e s i n c e environmental c o v a r i a n c e was p o s s i b l y overestimated due t o the incomplete adjustment f o r year of c a l v i n g . Secondly, c u r r e n t l a c t a t i o n c o r r e l a t i o n s may have been i n f l a t e d due to confounded age and s i r e e f f e c t s . Both s e t s of c o r r e l a t i o n e s t i m a t e s were 67 used i n the assessment of the g e n e t i c r e l a t i o n s h i p s between pro d u c t i o n and serum t r a i t s , with the r e s e r v a t i o n t h a t those i n v o l v i n g f i r s t l a c t a t i o n production were probably more r e a l i s t i c , Futhermore, no c l e a r c u t d i s t i n c t i o n s were d i s c e r n a b l e between the two production groups on the b a s i s of the e s t i m a t e s obtained i n t h i s study. The t r e n d s of the c o r r e l a t i o n s a l r e a d y d i s c u s s e d were s i m i l a r f o r both production t r a i t groups. Some d i s c r e p a n c i e s arose but none were so s e r i o u s or patterned as to be u s e f u l i n d e c l a r i n g e i t h e r f i r s t or c u r r e n t l a c t a t i o n s as a p r e f e r r e d standard, & more ge n e r a l p i c t u r e o f the r e l a t i o n s h i p s i n v o l v i n g the production t r a i t s and the s e l e c t e d serum c o n s t i t u e n t s may be d i s c e r n e d by d i s c u s s i n g the serum t r a i t s t h a t were most h e a v i l y i n v o l v e d . C r e a t i n i n e and a l k a l i n e phosphatase, the serum t r a i t s with the h i g h e s t h e r i t a b i l i t y , were the t r a i t s most h i g h l y c o r r e l a t e d with the production t r a i t s . These two c o n s t i t u e n t s c o r r e l a t e d h i g h l y n e g a t i v e l y with a l l p r o d u c t i o n t r a i t s except c r e a t i n i n e with c u r r e n t l a c t a t i o n milk. There was a p a r t i c u l a r l y strong r e l a t i o n s h i p between a l k a l i n e phosphatase and the c u r r e n t p r o d u c t i o n t r a i t s . These r e l a t i o n s h i p s were shown to be r e l i a b l e by the r e l a t i v e l y low standard e r r o r s . Potassium was another t r a i t t h a t was i n v o l v e d with milk production and r e t a i n e d a p a t t e r n f o r both p r o d u c t i o n e s t i a a t e s . I t c o r r e l a t e d p o s i t i v e l y with milk and p r o t e i n production but 68 d i d not show a strong r e l a t i o n s h i p with milk f a t . The remaining s e l e c t e d serum c o n s t i t u e n t s d i d not show str o n g , c o n s i s t e n t c o r r e l a t i o n s with the production c o n s t i t u e n t s . Albumin was p o s i t i v e l y c o r r e l a t e d with both measures of milk production but, with regards . to f a t and p r o t e i n , the c o r r e l a t i o n s were not s i g n i f i c a n t f o r both estimates and thus were c o n s i d e r e d as not p a r t i c u l a r i t y s t r o n g . Amylase and BON showed str o n g c o r r e l a t i o n s with some milk t r a i t s t u t only i n the f i r s t l a c t a t i o n . S G O T showed no str o n g c o r r e l a t i o n s . T h i s study has focused on those t r a i t s which were judged t o have a s i g n i f i c a n t g e n e t i c component. Animal breeding theory s t a t e s t h a t progress due t o s e l e c t i o n i s p r o p o r t i o n a l to the g e n e t i c v a r i a n c e and the h e r i t a b i l i t y of the t r a i t . A s m a l l g e n e t i c component r e l a t i v e to the phenotypic v a r i a b i l i t y w i l l r e s u l t i n both parameter es t i m a t e s being low. Thus, any t r a i t s with a low h e r i t a b i l i t y were not deemed as important as those t h a t posessed a s i g n i f i c a n t a d d i t i v e component s i n c e the t r a i t s with low h e r i t a b i l i t i e s would not be expected t o progress under s e l e c t i o n a t an acceptable r a t e . In f u t u r e s t u d i e s , i f one were able t o more p r e c i s e l y i d e n t i f y t h i s environmental component, the r e l a t i v e importance of the a d d i t i v e v a r i a n c e would i n c r e a s e . This would r e s u l t i n a more accurate assessment of the u s e f u l n e s s of u r i c a c i d and i t s g e n e t i c r e l a t i o n s h i p s with other t r a i t s . 69 I n d i r e c t s e l e c t i o n o f f e r s an a l t e r n a t i v e t o the d i r e c t s e l e c t i o n of a t r a i t i n modern animal breeding theory. Response to d i r e c t s e l e c t i o n i s p r o p o r t i o n a l t o a d d i t i v e v a r i a n c e , h e r i t a b i l i t y and s e l e c t i o n d i f f e r e n t i a l . , Response t o i n d i r e c t s e l e c t i o n depends on the h e r i t a b i l i t y o f the t r a i t used i n d i r e c t l y , the g e n e t i c v a r i a n c e of the t r a i t i n which change i s sought, the g e n e t i c c o r r e l a t i o n between the two t r a i t s and the s e l e c t i o n d i f f e r e n t i a l . The success of i n d i r e c t s e l e c t i o n compared to d i r e c t s e l e c t i o n w i l l depend on the r e l a t i v e magnitude of these f a c t o r s . I n p r a c t i c e , ease and economy of measurement may become a c o n s i d e r a t i o n i n t r a i t s e l e c t i o n . A r a t i o n a l d e c i s i o n must be reached between the s t r e n g t h of the g e n e t i c system and the c o n s i d e r a t i o n s of i t s p r a c t i c a l use. Some i l l u m i n a t i o n o f the r e l a t i o n s h i p s between the serum t r a i t s w i l l provide support f o r making t h i s d e c i s i o n . Table VIII presents the g e n e t i c and phenotypic c o r r e l a t i o n s among those serum c o n s t i t u e n t s judged t o be s i g n i f i c a n t l y h e r i t a b l e . Included i n t h i s t a b l e are c o r r e l a t i o n s c f s u f f i c i e n t magnitude to be of i n t e r e s t and which have a s s o c i a t e d standard e r r o r s o f low r e l a t i v e magnitude, i n d i c a t i n g some degree of r e l i a b i l i t y . Unlike the c o r r e l a t i o n s i n v o l v i n g the milk production t r a i t s , t h e r e were not two estimates of the same c o r r e l a t i o n a v a i l a b l e . T h e r e f o r e , there c o u l d be no c o r r o b o r a t i o n w i t h i n t h i s present study o f the e s t i m a t e s o b t a i n e d . ; C r e a t i n i n e , the most h e r i t a b l e o f the serum t r a i t s . Table VIII. Genetic (above diaqonal) and phenotypic (below diaqonal) c o r r e l a t i o n s amonq s e l e c t e d serun c o n s t i t u e n t s . I T r a i t 1 1 h* I Creat Alk P Amyl K Alb SGOT i BUN | 1 Creat I .32481.1328 .3451.299 .5941.283 -.4011.400 -.2601. 416 .2661.510 -.2141.598 I I Alk P I .29941.1283 I .1051.079 -.4461.346 -.6571.394 -.0841.468 -1.01t.660 -.0481.585 | I Amyl I . 2024t. 1085 I .0631.079 -.0091.075 .3171.453 .0081.516 1.46l1.03 -1.291.944 | 1 K I .12881.0921 I .1051.073 -.0841.068 .0311.066 .7571.546 1. 101.793 -.7011.998 | I Alb I .08521.0810 1 .1191.070 - .0641 .066 .1461.063 .0591.061 .9191.955 1.45*1.09 I I SGOT I .05221.0739 1 .0311.067 .C871.069 .0291.063 .0341.060 -.0201.057 0.0 I I BOH I .04621.0718 1 -.0661.064 -.0231.064 -.0261.062 .1221.058 .0801.056 .0371.054 71 e x h i b i t e d few strong g e n e t i c c o r r e l a t i o n s with other serum c o n s t i t u e n t s . With regards to g e n e t i c c o r r e l a t i o n s with the h e r i t a b l e blood c o n s t i t u e n t s , c r e a t i n i n e was r e l a t e d p o s i t i v e l y with a l k a l i n e phosphatase (0.345), although the standard e r r o r d i d not i n d i c a t e t h a t t h i s degree of c o r r e l a t i o n was well d e f i n e d . The c o r r e l a t i o n of c r e a t i n i n e with amylase was s t r o n g e r (0.594) and more r e l i a b l e as i n d i c a t e d by the standard e r r o r . I t appeared t h a t amylase and a l k a l i n e phosphatase have a genotype t h a t i s i n part common with t h a t o f c r e a t i n i n e . Amylase was moderately h e r i t a b l e and the most e f f i c i e n t method of s e l e c t i o n would be that o f d i r e c t s e l e c t i o n f o r amylase l e v e l . SGOT, a t r a i t which had a h e r i t a b i l i t y judged to be s t a t i s t i c a l l y i n s i g n i f i c a n t , had a number of strong c o r r e l a t i o n s with the h e r i t a b l e serum c o n s t i t u e n t s . I t was p r e v i o u s l y pointed out that l i t t l e progress c o u l d be expected under d i r e c t s e l e c t i o n f o r SGOT s i n c e i t s h e r i t a b i l i t y was low (0.052). I n d i r e c t s e l e c t i o n would be an improvement i f t r a i t s c o u l d be l o c a t e d with l a r g e r h e r i t a b i l i t i e s and s t r o n g c o r r e l a t i o n s with SGOT. S e v e r a l serum t r a i t s possessed these c h a r a c t e r i s t i c s . Amylase was moderately h e r i t a b l e (0.20 2) and had a c o r r e l a t i o n with SGOT of 1.46. This l a r g e c o r r e l a t i o n was r easonably r e l i a b l e when judged on the b a s i s of i t s standard e r r o r . T h i s i n d i c a t e d a high degree of s i m i l a r i t y i n the genotypes r e s p o n s i b l e f o r the two t r a i t s . C o r r e l a t i o n s were o n l y s l i g h t l y l e s s s t r o n g f o r SGOT with a l k a l i n e phosphatase (-1.01), 72 potassium (-1.10) and albumin (0.919). A reasonable degree of success could be expected i n moving the l e v e l of SGOT by s e l e c t i n g f o r any of these c o n s t i t u e n t s . , BUN was i n much the same s i t u a t i o n as SGOT. Not s i g n i f i c a n t l y h e r i t a b l e , i t possessed l a r g e g e n e t i c c o r r e l a t i o n s with c e r t a i n h e r i t a b l e t r a i t s . One of these t r a i t s was albumin, which has low, s i g n i f i c a n t h e r i t a b i l i t y and a g e n e t i c c o r r e l a t i o n of 1.45 with BUN. Amylase* which had a moderate h e r i t a b i l i t y , had a c o r r e l a t i o n with BUN of -1.29., I t was apparent t h a t , on the b a s i s of t h i s study, the most s u c c e s s f u l method of a l t e r i n g the pop u l a t i o n l e v e l of BUN would be to s e l e c t f o r a lower l e v e l of amylase. I t should be noted t h a t some of these c o r r e l a t i o n s i n v o l v i n g SGOT and BUN exceeded the t h e o r e t i c a l range of the c o r r e l a t i o n s t a t i s t i c t o some degree. However, the standard e r r o r s were s m a l l enough, r e l a t i v e t o the c o r r e l a t i o n e s t i m a t e s t o i n d i c a t e a degree of confidence i n the high values f o r some c o r r e l a t i o n s . That they exceeded the t h e o r e t i c a l l i m i t was a r e f l e c t i o n of s e v e r a l f a c t o r s . One was the f a c t t h a t one of the t r a i t s i n v o l v e d had a s m a l l g e n e t i c component. Combined with rounding e r r o r s and e r r o r s i n v o l v e d i n the e s t i m a t i o n o f var i a n c e and co v a r i a n c e components, t h i s s m a l l g e n e t i c component caused wide f l u c t u a t i o n s i n the estimates. Due to the s a a l l e r standard e r r o r s , these c o r r e l a t i o n s were taken to i n d i c a t e t h a t the genotypes of the t r a i t s i n v o l v e d were h i g h l y s i m i l a r . Other g e n e t i c c o r r e l a t i o n s e x i s t e d among serum c o n s t i t u e n t s 73 and seemed r e l i a b l e on the b a s i s of t h e i r standard e r r o r s , but were not as l a r g e i n magnitude as those a l r e a d y mentioned. A l k a l i n e phosphatase was n e g a t i v e l y c o r r e l a t e d with amylase (-0.446) and t h i s e s t imate was r e l a t i v e l y r e l i a b l e , A l k a l i n e phosphatase a l s o c o r r e l a t e d n e g a t i v e l y with potassium (-0,657) with a reasonable standard e r r o r . , F i n a l l y , potassium c o r r e l a t e d p o s i t i v e l y with albumin (0,757),, These l a s t t h r e e r e l a t i o n s h i p s were of l i m i t e d usefulness,,, A l l three r e l a t i o n s h i p s i n v o l v e d h e r i t a b l e t r a i t s and t h e r e f o r e d i r e c t s e l e c t i o n should be s u c c e s s f u l i n a l t e r i n g p o p u l a t i o n l e v e l s . The magnitude of the c o r r e l a t i o n s among these t h r e e c o n s t i t u e n t s was not s u f f i c i e n t l y l a r g e to propose the use of i n d i r e c t s e l e c t i o n . <• The preceeding d i s c u s s i o n of the c o r r e l a t i o n s estimated i n t h i s study pointed out the complex g e n e t i c r e l a t i o n s h i p s u n d e r l y i n g some of the compounds and elements found i n the serum of d a i r y c a t t l e . Besides being of i n t e r e s t t o g e n e t i c i s t s , these r e l a t i o n s h i p s c o u l d prove i n t e r e s t i n g as background r e l a t i o n s h i p s i n the i n t e r p r e t a t i o n of r e s u l t s frcm p h y s i o l o g i c a l experiments. As an example, SGOT and potassium e x h i b i t e d a higher p o s i t i v e g e n e t i c c o r r e l a t i o n (1.100) but s m a l l environmental (-0.060) and phenotypic (0.034) c o r r e l a t i o n s . . T h i s i n d i c a t e d a very s i m i l a r genotype but a l a r g e environmental i n p u t on these t r a i t s . I f a c o r r e l a t e d response i n these two t r a i t s were noted i n a t r i a l i n v o l v i n g s m a l l numbers o f animals, i t c o u l d be due merely t o a sampling anomaly r a t h e r than due t o the treatments present i n the t r i a l . 74 The same r a t i o n a l e can be extended t o a l l other c o r r e l a t i o n s estimated i n t h i s study. A p r e l i m i n a r y i n v e s t i g a t i o n of the r e s u l t s of t h i s study would b e n e f i t r e s e a r c h e r s i n other f i e l d s by forewarning them of the g e n e t i c consequences r e l e v a n t t o t h e i r present experiments. 75 CCNCLUSICN T h i s study has estimated and e v a l u a t e d f o r some serum and milk production t r a i t s the g e n e t i c parameters t h a t are necessary f o r using these t r a i t s i n a breeding program. Among the parameters estimated were the g e n e t i c components of v a r i a n c e and the h e r i t a b i l i t i e s o f the i n d i v i d u a l t r a i t s . I t was suggested t h a t to be of g r e a t e s t i n t e r e s t , a t r a i t should possess moderate to high h e r i t a b i l i t y . , T h i s would allow the animal breeder t o change the l e v e l of e x p r e s s i o n of a t r a i t i f such a change were shown to be d e s i r a b l e . The d e s i r a b i l i t y of a t r a i t i n t h i s study was f u r t h e r e v a l u a t e d i n terms of the g e n e t i c r e l a t i o n s h i p s among the serum and production t r a i t s . S i n c e i t i s probable t h a t these represented o n l y a s m a l l p o r t i o n of the r e l a t i o n s h i p s o f i n t e r e s t i n v o l v i n g serum c o n s t i t u e n t s i n d a i r y c a t t l e , t h i s study was i n p a r t a r e p o r t o f g e n e t i c parameters o f serum c o n s t i t u e n t s as a r e f e r e n c e f o r l a t e r s t u d i e s , ; The p r o d u c t i o n o f m i l k , milk f a t and milk p r o t e i n e x h i b i t e d moderate h e r i t a b i l i t y , a f i n d i n g t h a t was not unexpected. The serum t r a i t s t h a t e x h i b i t e d t h i s degree of h e r i t a b i l i t y were c r e a t i n i n e , a l k a l i n e phosphatase, amylase* potassium and albumin. SGOT and BOH e x h i b i t e d low h e r i t a b i l i t y but were hypothesized to be o f p o s s i b l e importance on the b a s i s of f i n d i n g s r e p o r t e d i n the l i t e r a t u r e . T h i s i n d i c a t e d t h a t progress c o u l d be achieved by d i r e c t s e l e c t i o n on the l e v e l o f these serum c o n s t i t u e n t s . The h e r i t a b i l i t i e s estimated i n t h i s 76 s t u d y were r e p o r t e d a s r e f e r e n c e v a l u e s f o r f u t u r e s t u d i e s i n v o l v i n g t h e a d d i t i v e g e n e t i c c o m p o n e n t s o f t h e s e t r a i t s , As an e v a l u a t i o n o f t h e r e l a t i o n s h i p s b e t w e e n t h e serum t r a i t s and t h e p r o d u c t i o n t r a i t s , g e n e t i c c o r r e l a t i o n s were e s t i m a t e d and d i s c u s s e d p a r t i c u l a r l y w i t h r e g a r d s t o t h e m a g n i t u d e o f t h e a s s o c i a t e d s t a n c a r d e r r o r s , ,-• F o r t h e e s t i m a t e s o f g e n e t i c c o r r e l a t i o n i n v o l v i n g t h e m i l k p r o d u c t i o n t r a i t s , two e s t i m a t e s were a v a i l a b l e i n t h i s s t u d y , one f o r c u r r e n t l a c t a t i o n and one f o r f i r s t l a c t a t i o n . F i r s t l a c t a t i o n e s t i m a t e s were c o n s i d e r e d somewhat s u p e r i o r t o c u r r e n t l a c t a t i o n e s t i m a t e s . B o t h were u s e d a s s e p a r a t e e s t i m a t e s o f t h e same p a r a m e t e r i n t h e d i s c u s s i o n . T h i s i n t u r n a l l o w e d t h e d i s c e r n i n g o f t h o s e r e l a t i o n s h i p s b e t w e e n s e r u m t r a i t s and p r o d u c t i o n t r a i t s t h a t were o f g r e a t e s t r e l i a b l i t y . The most c o n s i s t e n t and r e l i a b l e g e n e t i c c o r r e l a t i o n s b etween s e r u m and p r o d u c t i o n t r a i t s were a s f o l l o w s . , Serum l e v e l o f p o t a s s i u m c o r r e l a t e d h i g h l y a nd p o s i t i v e l y w i t h m i l k p r o d u c t i o n f o r b o t h f i r s t a n d c u r r e n t l a c t a t i o n s . A l b u m i n l e v e l a l s o p o s s e s s e d a h i g h , p o s i t i v e c o r r e l a t i o n w i t h m i l k p r o d u c t i o n . The s t r o n g e s t r e l a t i o n s h i p s i n v o l v e d a l k a l i n e p h o s p h a t a s e and c r e a t i n i n e w i t h t h e p r o d u c t i o n t r a i t s . , G e n e t i c c o r r e l a t i o n s o f a l k a l i n e p h o s p h a t a s e w i t h a l l t h r e e p r o d u c t i o n t r a i t s were n e g a t i v e and i n v o l v e d t h e h i g h e s t m a g n i t u d e o f a n y o f t h e c o r r e l a t i o n s o f t h e h e r i t a b l e serum t r a i t s w i t h t h e p r o d u c t i o n t r a i t s . C r e a t i n i n e was n e g a t i v e l y c o r r e l a t e d w i t h m i l k p i c t e i n 77 and o i l k f a t . C o r r e l a t i o n of c r e a t i n i n e l e v e l with milk production was not s t r o n g . These f i n d i n g s e f f e c t i v e l y reduced the o r i g i n a l nineteen serum c o n s t i t u e n t s i n t o a subset that has shown a g e n e t i c component and/or has e x h i b i t e d r e l a t i o n s h i p s with the p r o d u c t i o n t r a i t s . T h i s study has i d e n t i f i e d such a subset and estimated h e r i t a b i l i t i e s and g e n e t i c c o r r e l a t i o n s as i n d i c a t i o n s of e x i s t i n g r e l a t i o n s h i p s , f o r the b e n e f i t of f u t u r e s t u d i e s . Other r e l a t i o n s h i p s examined were those t h a t e x i s t e d among the serum c o n s t i t u e n t s . T h i s was i n v e s t i g a t e d f o r two reasons. One was to assess the p o s i b i l i t y of u t i l i z i n g i n d i r e c t s e l e c t i o n i n changing the l e v e l o f a c o r r e l a t e d , n o n h e r i t a b l e t r a i t . Second, and most important was t o use the g e n e t i c c o r r e l a t i o n as an assessment o f the u n d e r l y i n g genotypic r e l a t i o n s h i p s , , These genotypic r e l a t i o n s could be o f use to r e s e a r c h e r s i n ether f i e l d s i n i n t e r p r e t i n g t h e i r r e s u l t s . G enetic c o r r e l a t i o n s were again taken as the method o f assessment. SGOT e x h i b i t e d s e v e r a l s t r o n g genetic c o r r e l a t i o n s - p o s i t i v e with amylase, potassium and albumin, and n e g a t i v e with a l k a l i n e phosphatase.. Since a l k a l i n e phosphatase and amylase possessed the highest h e r i t a b i l i t i e s of these t r a i t s , s e l e c t i o n on these two t r a i t s should be s u c c e s s f u l i n a l t e r i n g the serum l e v e l of SGOT, a t r a i t of low h e r i t a b i l i t y . BON e x h i b i t e d a s t r o n g n e g a t i v e c o r r e l a t i o n with amylase and a s t r o n g p o s i t i v e c o r r e l a t i o n with albumin., Since BON had low h e r i t a b i l i t y , s e l e c t i o n on amylase l e v e l should r e s u l t i n an i n d i r e c t change i n BON l e v e l . 78 G e n e t i c c o r r e l a t i o n s among the h e r i t a b l e serum t r a i t s sere not as s p e c i f i c a l l y u s e f u l i n i n d i r e c t s e l e c t i o n but were i n d i c a t i v e of u n d e r l y i n g g e n e t i c r e l a t i o n s h i p s . C r e a t i n i n e e x h i b i t e d moderate p o s i t i v e c o r r e l a t i o n s with a l k a l i n e phosphatase and amylase. a d d i t i o n a l l y , a l k a l i n e phosphatase e x h i b i t e d moderate negative c o r r e l a t i o n with amylase and potassium. F i n a l l y , a moderate, p o s i t i v e c o r r e l a t i o n e x i s t e d between potassium and albumin. T h i s study has been s u c c e s s f u l i n i d e n t i f y i n g a subset of the serum t r a i t s measured t h a t were of i n t e r e s t on the b a s i s of the h e r i t a b i l i t y of the t r a i t and i t s g e n e t i c c o r r e l a t i o n s with other serum and production t r a i t s . These ge n e t i c parameters are t a b u l a t e d as a r e f e r e n c e source as w e l l as a source of guidance i n f u t u r e s t u d i e s i n v o l v i n g these t r a i t s . 79 Arave, C. B. H, M i l l e r and B. C. Lamb, 1975. Genetic and Environmental E f f e c t s on Serum C h o l e s t e r o l Levels of Dairy C a t t l e of Vari o u s Ages. J . Dairy S c i . 58:423-1*27. B e t t i n i , T. H., D. Matassino, F. Consentino, C. I a n n e l l i , P. Hasina and fl. Z a c h i , 1975. 12 Haematochemical Parameters i n I t a l i a n F r i e s i a n Cows. Animal Breeding A b s t r a c t s 44 No.1:9. Bondar, B. J . 1. and D. C. Head, 1974. 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Chem,, 10:686-703, K i t c h e n h a m , B, A. a n d G,, J . l o w l a n d s , 1976, D i f f e r e n c e s i n t h e C o n c e n t r a t i o n s o f C e r t a i n B l o o d C o n s t i t u e n t s Among Cows i n a D a i r y H e r d . , J , A g r . / S c i . 86: 171-179. K i t c h e n h a m , B. A., G. J . R o w l a n d s and H. S h o r b a j i , 1975. R e l a t i o n s h i p s o f C o n c e n t r a t i o n s o f C e r t a i n B l o o d C o n s t i t u e n t s w i t h M i l k Y i e l d a n d Age o f Cows i n D a i r y H e r d s . Res. V e t . S c i . 18:249-252. K u n k e l , H., D., D. K. S t o k e s , J r . , W. B, A n t h o n y and M,, F, F u t r e l l , 1 9 5 3 . Serum A l k a l i n e P h o s p h a t a s e A c t i v i t y i n E u r o p e a n a n d Brahman C a t t l e and T h e i r C r o s s b r e d T y p e s . J . Anim. S c i . 12:765-770. L e v i n e , J . , S. M o r g a n s t e r n and D., V l a s t e l i c a , 1S67. 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E f f e c t s of Breed, Stage of l a c t a t i o n , and Season of Year on T h y r o i d S e c r e t i o n Bate of Dairy Cows as Determined by the Chemical Thyroxine Turnover Method. J . Dairy S c i . 45: 999-1002. , Borganstern, S., G. K e s s l e r , J . Auerbach, B. V. F l c r and B. K l e i n , 1965. An Automated p-Sitrophenylphosphate Serum A l k a l i n e Phosphatase Procedure f o r the AutcAnalyzer. C l i n . Chem. y 11:876-888. florganstern, S., M. Oklander, J . Auerbach, 3. Kaufman and B. K l e i n , 1966. Automated Determination of Serum Glutamic O x a l o a c e t i c Transaminase. C l i n . Chem. 12:95-111. Hylr e a , P. J . and P. J . Healy, 1968. C o n c e n t r a t i o n s of Some Components i n the Blood and Serum of Apparently Healthy D a i r y C a t t l e . Aust. Vet.; J . 44:570-573. Payne, J . M., G. J . Rowlands, B. Manston and S. / M. Dew, 1973, A S t a t i s t i c a l A p p r a i s a l of the B e s u l t s of Met a b o l i c P r o f i l e T ests on 75 D a i r y Herds. B r i t . Vet, J . 129:370-381. Payne, J . M., G. 3., Bowlands, B. Hanston, S., 8. Dew and R. H. Parker, 1974, A S t a t i s t i c a l A p p r a i s a l of the B e s u l t s of t h e Metabo l i c P r o f i l e T e s t s on 191 Herds i n the BVA/ADAS J o i n t E x e r c i s e i n Animal Health and P r o d u c t i v i t y , , E r i t . Vet. J . 130:34-43. Peterson, 8., G. and D. E. Baldern, 1978. Serum C o n s t i t u e n t s 82 i n Dairy C a t t l e as A f f e c t e d by Feeding Regime, Age, L a c t a t i o n and Pregnancy* Estimates of the C o r r e l a t i o n s of the Serum C o n s t i t u e n t s Between Repeated Samples o f the Same Animal. Unpublished Research. P i r c h n e r , F., 1969. P o p u l a t i o n Genetics i n Animal Breeding. H. H. , Freeman and Co., San F r a n c i s c o . P r e w i t t , L. R. , A. F. K e r t z , A. G. Lane, *3. B. Campbell and D. , E. Seinman, 1S71. E f f e c t s of D i e t a r y P r o t e i n on Blood, Orine and Milk Composition.; Amer. J. Vet. Res. , 32:393-397. , Binderknecht, H, , E. P. Marbach, C. R. Carmack, C. Conteas and M. C. Geokas, 1971. C l i n i c a l E v a l u a t i o n of an a-Amylase Assay with I n s o l u b l e Starch L a b e l l e d with B e m a z o l b r i l l i a n t Blue (Amylopectin-Azure). C l i n . Biochem. 4:162-164. Robertson, A., 1959. Experimental Design i n the E v a l u a t i o n of G e n e t i c Parameters. B i o m e t r i c s 15:219-226. Robertson, A., 1966. , B i o c h e m i c a l Polymorphisms i n animal Improvement. Xth European Conference on A n i i a l Blood Groups and B i o c h e m i c a l Polymorphisms:35-42.j Boss, J . and ». G., H a l l i d a y , 1976. Surveys of Bovine Blood Chemistry i n S c o t l a n d . I I Serum P r o t e i n s , C h o l e s t e r o l , Calcium, Sodium, Potassium and Magnesium. B r i t . Vet. J . 132:401-404., Bou s s e l , J . 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Serum P r o t e i n C o n c e n t r a t i o n s , as a Fun c t i o n c f Age, i n Female Dairy C a t t l e . C o r n e l l Vet.,, 63:65-71. Tumbleson, M. E,, 8. E. B i n g f i e l d , H. / D. Johnson, J . B. Campbell and C. C. H i d d l e t o n , 1973b, Serum E l e c t r o l y t e C c n c e n t r a t i o n s , as a Fu n c t i o n of Age, i n Female Dairy C a t t l e . C o r n e l l Vet. 63:58-64. H i l s c n , 1. L, and C, A. D i n k e l , 1968, Blood Composition of Hereford S t e e r s , I I E f f e c t s of Banch and S i r e . J . Anim. S c i . , 27:1092-1096. , Appendix. Number o f o b s e r v a t i o n s f o r each p a i r o f t r a i t s . — 1 — TRAIT | l l i l k l Fat 1 Protl Milk - = « = = = + = ========== ================= ========== ========== ( l i l k l | Fat 1 I 450 P r o t l | 101 101 HilkC I U26 126 38 2 Fat C | 126 126 382 512 ProtC I 388 388 38 2 459 Ca | 139 139 395 501 P01 | 124 121 386 187 Glue I 440 140 395 502 BUN | 440 140 395 502 Uric I 111 111 396 503 Chol I 138 438 391 500 T P I 410 110 396 502 Alb | 440 140 395 502 B i l i I 137 137 393 199 Alk P | 439 139 391 500 SGOT | 431 131 391 196 Creat 1 445 115 398 506 T r i q I 111 144 396 501 Na t 136 136 388 194 K I 136 436 389 191 Cl 1 435 135 387 495 HC03 I 135 435 387 195 TU | 449 119 401 511 Amyl I 4 35 135 388 191 F a t C P r o t C Ca P01 Glue 459 501 452 487 441 511 502 452 533 516 502 452 533 515 534 503 453 531 516 535 50 0 451 531 513 532 50 2 453 533 515 534 502 452 533 516 535 499 450 530 513 531 500 450 531 513 532 496 418 527 511 528 506 454 52 9 511 530 50 4 152 526 508 527 191 441 516 198 517 191 112 516 198 517 195 412 517 199 518 495 112 517 199 518 511 158 531 516 535 494 112 516 199 518 CO A p p e n d i x ( c o n t . ) . Nunber o f o b s e r v a t i o n s f o r each p a i r of t r a i t s . TBAIT n i l k l F a t 1 P r o t l H i l k C F a t C P r o t c Ca P04 G l u e BON O r i c C h o i T P A l b B i l i A l k P SGCT C r e a t T r i g Na X C l HCG3 . T4 A a y l BON O r i c C h o i T P Alb 535 532 534 534 531 532 528 530 527 517 517 518 518 535 517 533 535 535 532 533 529 531 528 518 518 519 519 536 518 532 532 52 9 530 526 52 8 525 515 515 516 516 533 515 534 531 532 528 530 527 517 517 518 518 535 517 531 532 528 530 527 517 517 518 518 535 518 B i l i A l k P SGOT C r e a t 529 527 526 527 528 524 524 525 521 535 514 515 511 523 514 515 511 523 515 516 512 524 515 516 512 524 532 533 529 539 514 515 511 524 CO Appendix (cont.). Nunber of observations f o r each pa i r of t r a i t s . i r- — i | TBAIT | T r i q Na K Cl HC03 T4 Anyl 1 ! « „ - « { « I Milk! | 1 ?at 1 | I P r o t l I I BilkC | 1 Fat C | | ProtC | 1 Ca | | P04 | 1 Glue 1 | BON | I Oric | 1 Choi I 1 T P | 1 Alb | 1 B i l i | I Alk F | 1 SGOT I 1 Creat | 1 T r i q I 1 Na | 520 1 K i 520 525 1 C l I 521 524 524 I HC03 | 521 524 524 527 1 Tt I 536 526 526 527 527 1 Amyl I 1 , X 521 515 515 514 514 526 1 ... 1 C O C M 

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