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Studies of solids-not-fat and butterfat in cow's milk and heritability estimates Vesely, John Anthony 1957

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STUDIES OF SOLIDS-NOT-FAT AMD BUTTERFAT IN COW'S MILK AND HERITABILITY ESTIMATES by John Anthony Vesely B.S.A., U n i v e r s i t y of B r i t i s h Columbia, 1 9 5 5 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN AGRICULTURE i n the D i v i s i o n of Animal Science We accept t h i s t h e s i s as conforming t o the standard r e q u i r e d from candidates f o r the de'gree of MASTER OF SCIENCE IN AGRICULTURE Members of the D i v i s i o n of Animal Science THE UNIVERSITY OF BRITISH COLUMBIA APRIL, 1 9 5 7 - i i i -ABSTRACT The main o b j e c t s of t h i s i n v e s t i g a t i o n were to study f a t and s o l i d s - n o t - f a t l e v e l s i n cow's milk, the r e l a t i o n s h i p be-tween them and to c a l c u l a t e h e r i t a b i l i t y e s t i m a t e s . During the p e r i o d of four months i n 1955-1956 the milk of twenty A y r s h i r e cows was sampled and t e s t e d f o r b u t t e r f a t and s o l i d s - n o t - f a t . In the same p e r i o d of 1956-1957 eighteen A y r s h i r e s and ten H o l s t e i n s were s i m i l a r l y t e s t e d . A y r s h i r e cows were used f o r h e r i t a b i l i t y d e t e r m i n a t i o n s and r e p r e s e n t a group of i n b r e d animals with a high average r e l a t i o n s h i p . A d e t a i l e d c a l c u l a t i o n of h e r i t a b i l i t y f o r f a t and s o l i d s -n o t - f a t and r e s u l t a n t estimates of 21.2$ and 10.9$ r e s p e c t i v e l y are presented. H i g h l y s i g n i f i c a n t c o r r e l a t i o n c o e f f i c i e n t s between f a t and s o l i d s - n o t - f a t of •»• 0.680 i n 1955-1956 and + 0.618 i n 1956-1957 f o r A y r s h i r e s and a n o n - s i g n i f i c a n t value of + 0.570 f o r H o l s t e i n s , were c a l c u l a t e d . The q u e s t i o n of te s t i n g " m i l k f o r s o l i d s - n o t - f a t with r e s p e c t to a c h i e v i n g g e n e t i c a l improvement i s expl o r e d and the u s e f u l n e s s of c o r r e l a t i o n c o e f f i c i e n t s and r e g r e s s i o n equations f o r e s t i m a t i n g s o l i d s - n o t - f a t i s d i s c u s s e d . The e f f e c t s of m a s t i t i s on the l e v e l of s o l i d s - n o t - f a t are i n d i c a t e d . I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f the r e q u i r e m e n t s f o r an advanced degree a t t h e U n i v e r s i t y o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y purposes may be g r a n t e d by t h e Head o f my Department o r by h i s r e p r e s e n t a t i v e . I t i s under-s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department o f The U n i v e r s i t y o f B r i t i s h Columbia, Vancouver 8, Canada. i -THE ACKNOWLEDGEMENT The author wishes t o acknowledge the i n v a l u a b l e a s s i s t a n c e of a number of p r o f e s s o r s who made t h i s study p o s s i b l e . F i r s t , he i s very indebted to Dean B.A. E a g l e s , the head of the Animal Science D i v i s i o n of the F a c u l t y of A g r i c u l t u r e , f o r h i s constant i n t e r e s t and ready a s s i s t a n c e . He would l i k e to thank Dr. J.C. Berry, h i s s u p e r v i s i n g p r o f e s s o r , f o r h i s guidance and astut e a d v i c e . Thanks are due Dr. J.J.R. Campbell and Dr. N. N e i l s o n f o r making a v a i l a b l e a l l necessary equipment and s u p p l i e s and f o r p r o v i d i n g needed i n f o r m a t i o n ; a l s o , thanks to Dr. C D . MacKenzie f o r h i s w i l l i n g n e s s to help whenever p o s s i b l e . L a s t l y , s i n c e r e thanks are extended to Dr. D. Blackmore, Senior Animal Husbandman, Experimental S t a t i o n at A g a s s i z , and Dr. V.C. B r i n k f o r i n v a l u a b l e advice i n c a r r y i n g through the s t a t i s t i c a l a n a l y s i s . - i i -TABLE. OF CONTENTS Page I. Introduction 1 II . Literature Review 6 Variation due to inherited factors 7 Variation due to the age of the animal 8 Variation due to the relati o n s h i p with milk y i e l d and butterfat percentage 9 Variation due to stage of lac t a t i o n 10 Variation due to season of the year 11 Long term trends 1 3 Variation due to plane of n u t r i t i o n 14 Variation due to hormones 15 Variation due to disease 16 Variation due to other causes 16 I I I . The History of the U.B.C. Dairy Herd . .... 20 IV. Experimental 22 Animals used and method of milk sampling ... 22 Management of the herd . . 23 Laboratory procedures for butterfat and solids-not-fat determination 24 V. A n a l y t i c a l Methods of H e r i t a b i l i t y Estimates .. 24 A n a l y t i c a l method used 30 Variance components analysis ( s t a t i s t i c a l model) 33 VI. Analysis of Data and Results 34 Half-sib correlation for solids-not-fat .... 34 Half-sib correlation for butterfat 38 H e r i t a b i l i t y estimates for solids-not-fat and butterfat 39 Comparison of data from 1955-1956 and 1956-1957 43 VII. Discussion • 48 VIII. Summary 60 IX. Appendices I, II , III 62-76 X. Covariance Chart Model 77 XI. Bibliography 78 INTRODUCTION One of the recent, and important trends i n d a i r y s c i e n c e and p r o d u c t i o n i s a m o d i f i e d concept of milk e v a l u a t i o n by the consumer, manufacturer and the s c i e n t i s t , from the n u t r i t i o n a l and economical p o i n t of view. On t h i s b a s i s , milk today i s a more important p a r t of man's d i e t because, i n a d d i t i o n to f a t , the n u t r i t i o n a l value i s emphasized of the very v a l u a b l e pro-t e i n s and v i t a m i n s , such as A,B,D,E, r i b o f l a v i n , and minerals mainly calcium and phosphorus. M i l k and milk products provide f o r the human d i e t , on the average, 10 per cent of the c a l o r i e s , 19 per cent of the p r o t e i n , over 40 per cent of the animal pro-t e i n , n e a r l y 50 per cent of the calcium, 12 per cent of the Vitamin A and a s i g n i f i c a n t p r o p o r t i o n of the B v i t a m i n s , i n -c l u d i n g 34 per cent of the r i b o f l a v i n . (Kay, 1956) The replacement of b u t t e r f a t i n the human d i e t a r y now pre s e n t s no d i f f i c u l t y . On the other hand, the replacement of the n o n - f a t t y c o n s t i t u e n t s of milk, while s c i e n t i f i c a l l y pos-s i b l e , i s at present e c o n o m i c a l l y and p r a c t i c a l l y out of the q u e s t i o n . - 2 -T a b l e s I and I I from the Commonwealth Economic Committee's annual r e p o r t , p u b l i s h e d i n 1 9 5 6 , show the i n c r e a s i n g demand f o r s o l i d s - n o t - f a t of milk based on higher p r o d u c t i o n and con-sumption per c a p i t a of cheese, powdered milk and skim milk, i n c o n t r a s t to a decreasing demand f o r b u t t e r f a t , mainly because of the competition with margarine. The composition of cow's milk v a r i e s under the e f f e c t s of v a r i o u s f a c t o r s , but on the average the milk components are as f o l l o w s : Fat 4 . 4 0 S o l i d s - n o t - f a t P r o t e i n Casein 2.80 Albumin 0 . 5 0 Lactose 4 « 9 5 Ash 0 . 7 5 9 . 0 0 Water 8 6 . 6 0 Today, a l l milk producers and d i s t r i b u t o r s are keenly aware of the l a r g e v a r i a t i o n s i n milk composition, i n r e s p e c t to both f a t and s o l i d s - n o t - f a t . I t i s w e l l known that one of the f a c t o r s causing the com-p o s i t i o n a l changes i n milk i s s e l e c t i v e b r e e d i n g . I t has been p o s s i b l e by long-term breeding p r a c t i c e s to i n c r e a s e the per-centage of b u t t e r f a t c o n s i d e r a b l y . There i s very l i t t l e evidence to suggest t h a t , l i k e the b u t t e r f a t l e v e l , the s o l i d s - n o t - f a t content could be i n c r e a s e d by s e l e c t i v e b r e e d i n g . To give the proper answer, the degree of h e r i t a b i l i t y of the s o l i d s - n o t - f a t needs to be known. - 3 -S c a r c i t y of knowledge on t h i s s ubject i s probably due i n p a r t , to the time and l a b o u r r e q u i r e d to c a r r y through a s u f f i c i e n t number of t e s t s to reach c o n c l u s i o n s of s t a t i s t i c a l s i g n i f i -cance. The present i n v e s t i g a t i o n was s p e c i f i c a l l y designed to o b t a i n i n f o r m a t i o n on the i n h e r i t a n c e of s o l i d s - n o t - f a t i n A milk of The U n i v e r s i t y of B r i t i s h Columbia d a i r y herd, and a l s o , to study the sources of c o m p o s i t i o n a l v a r i a t i o n s . A great number of r e s e a r c h e r s have been working i n p r e v i o u s years on the causes of v a r i a t i o n i n m i l k q u a l i t y . The m a t e r i a l used was mostly l a r g e p o p u l a t i o n samples, and t h e r e f o r e i t was de-s i r a b l e to compare t h e i r r e s u l t s with those of a small c l o s e d p o p u l a t i o n , such as the U.B.C. d a i r y herd. To c a r r y through t h i s r e s e a r c h work, i t was necessary to become acquainted with a l l problems i n milk q u a l i t y v a r i a -t i o n . In the f o l l o w i n g , the author attempts to review r e -search done on t h i s s u b j e c t i n the p a s t . A Henceforth The U n i v e r s i t y of B r i t i s h Columbia w i l l be r e f e r r e d to as The U.B.C. TABLE I Pr o d u c t i o n of b u t t e r , margarine, cheese and powder milk i n c e r t a i n c o u n t r i e s (thousand cwt.) Country- Product 1938 1951 1952 1 9 5 3 1 9 5 4 1 9 5 5 United B 400 1 1 2 144 306 460 316 Kingdom M 4,160 8 , 9 2 3 8 , 8 9 2 8,120 7,584 7 , 3 3 0 CH 860 878 1 ,102 1,758 1,631 1,261 P.M. 1 7 2 408 386 462^ 428 441 S.M. 306 80 128 3 9 0 558 451 New Zealand B M 3 , 0 1 7 3 ,875 4 ,052 3 , 7 1 0 3,831 4 , 0 9 0 a CH P M 1,705 1 , 9 1 4 2 ,154 2,068 2 , 0 4 5 1 , 9 2 7 r • vi • S.M. 156 6 3 6 773 796 624 7 0 4 Canada B 3,216 2 ,554 2 ,734 2,908 2 , 9 8 8 3,020 M - 939 9 9 1 987 1 , 0 3 5 1 , 1 1 7 CH 1 , 1 3 4 9 2 7 7 4 2 842 938 899 P.M. 59 156 1 4 4 167 168 186 S.M. 255 471 788 740 744 779 U. S. A. B 20,001 12 ,887 12 ,515 14,347 14,533 13,852 M 3 , 4 4 0 9 , 2 9 2 11 ,482 11,534 12,182 1 1 , 9 0 5 CH 6,476 10 ,369 10 ,449 1 2 , 0 0 4 12,349 12,084 P.M. 1 9 2 1 ,170 908 9 3 2 838 9 2 2 S.M.. 4,012 6 , 4 0 0 7 ,933 11,016 12,691 13,403 Denmark B 3,728 3 , 3 0 9 3 , 0 3 7 3,399 3,563 3,252 M 1,600 1 , 4 4 0 1 ,510 1 , 5 7 0 1,644 1,677 CH 703 1 , 5 2 4 1 ,697 1 , 7 1 1 1,594 1 , 7 2 6 P.M. 21 151 2 0 9 169 120 S.M. 21 53 61 109 63 Netherland B 1,993 1 ,645 1 ,449 1,640 1,612 1,457 M 1,405 3 ,445 3 ,702 3,977 4,594 4 , 9 1 1 CH 2,476 2 ,761 2 ,808 3,102 3 , 1 9 1 3,377 P.M. 285 3 9 0 619 481 4 7 2 619 S.M. 2 7 1 284 354 577 659 431 France B 4,200 5 , 4 1 3 4 , 9 2 1 5,433 4 , 9 2 1 4,980 M 6 9 0 1 ,102 1 , 4 9 6 1,673 CH 4,626 5 ,118 5 ,610 5,826 6,378 6 , 2 9 9 P.M. 82 • • • • • • • • • • 337 315 394 B . B u t t e r M = Margarine CH = Cheese P.M. s Whole milk powder S.M. = Skim milk powder - 5 -TABLE I I Estimated per c a p i t a consumption of b u t t e r , marg?arine, cheese, and powder milk i n c e r t a i n c o u n t r i e s l b s .  Country Product 1 9 3 8 1 9 5 1 1 9 5 2 1 9 5 3 1 9 5 4 1 9 5 5 U n i t e d B 24 . 1 14 10 • 9 13 . 2 14 . 0 14 . 6 Kingdom M 10 . 0 18 . 7 19 . 3 17 . 8 18 . 3 17 • 9 CH 8 • 9 10 . 5 7 . 7 9 . 3 9 . 4 9 . 0 P.M. . 6 1 . 4 1 . 2 , 1 . 5 1 . 4 1 • 3 S.M. . 8 1 . 8 1 . 3 1 . 2 1 • 9 1 . 8 New Zealand B M 42 . 8 42 • 7 4 4 . 0 45 . 0 45 . 1 45 . 4 11 CH 4 . 5 5 . 7 6 . 0 5 . 8 6 . 0 6 . 0 P.M. 4 . 7 7 . 2 6 • 9 7 . 5 6 . 3 6 . 0 S.M. 4 . 7 2 . 0 1 •9 2 . 0 2 . 4 2 . 0 Canada B 3 1 • 9 21 . 2 20 . 8 20 • 9 2 0 . 7 2 0 . 6 M - 7 . 4 7 . 7 7 . 5 7 . 6 8 . 1 CH 3 . 6 5 • 7 5 . 8 6 . 2 6 . 4 6 . 6 P.M. . 1 • 4 • 4 • 4 . 3 . 2 S.M. 1 .8 3 • 7 3 . 5 4 . 4 4 • 7 5 . 2 U. S. A. B 16 . 4 9 . 4 8 . 5 8 . 4 8 • 7 8 • 9 M 2 • 9 6 • 5 7 . 8 7 • 9 8 . 3 8 . 0 CH 5 . 8 7 . 1 7 • 5 7 . 3 7 . 8 7 . 7 P.M. . 1 • 3 . 5 . 3 . 2 . 2 S.M. 2 . 1 4 . 2 4 . 6 4 . 1 5 . 1 5 • 9 Denmark B 18 . 3 15 . 7 17 . 6 18 . 5 19 . 2 18 . 7 M 47 • 4 37 . 3 3 8 . 8 4 0 . 1 4 1 . 0 41 • 9 CH 14 . 1 14 .1 12 . 6 11 . 0 11 . 5 14 . 6 P.M. - - — — — S.M. - - - - - -Wetherland •B 12 • 3 6 . 2 5 . 5 6 . 2 6 • 4 6 . 6 M 15 • 7 37 . 0 39 . 0 40 . 6 4 1 . 4 42 . 3 CH 17 . 0 13 • 3 12 • 9 14 . 1 14 • 3 15 . 4 P.M. - - - _ - — S.M. - - - - - -France B M • • • • 13 . 0 13 . 7 14 . 8 12 . 6 12 . 6 JLI CH • • • • • • • • • • 14 • • . 1 • • 14 • • . 6 • • 14 • • . 6 • • 16 • • . 1 • • 15 • • . 4 P.M. - - - - - — S.M. — — — — - 6 -LITERATURE REVIEW The d e t e r m i n a t i o n of the s o l i d s i n m i l k i s u s u a l l y under-taken i n two f r a c t i o n s , the f a t and the s o l i d s - n o t - f a t . The s o l i d s - n o t - f a t f r a c t i o n c o n s i s t s of a l a r g e number of sub-stances of which the most important are c a s e i n , l a c t o s e and ash. The q u a n t i t i e s of these and of the other components can vary independently of each other, so that v a r i a t i o n i n the t o t a l s o l i d s - n o t - f a t f r a c t i o n i s the r e s u l t of the sum of the v a r i a t i o n s i n i t s components. The determined l e v e l of s o l i d s - n o t - f a t i n milk v a r i e s somewhat with the method of e s t i m a t i o n . There are two common methods used; the lactometer method and a g r a v i m e t r i c method i n t r o d u c e d by Golding (1934)« Both methods estimate the t o t a l s o l i d s from which the b u t t e r f a t percentage i s s u b t r a c t e d to o b t a i n the s o l i d s - n o t - f a t . The f i r s t of these methods i s used most widely owing to i t s s i m p l i c i t y , but i t i s not recommended f o r s c i e n t i f i c work because the percentages c a l c u l a t e d by t h i s method f a l l lower than those determined g r a v i m e t r i c a l l y . The l a r g e s t d i s c r e p e n c i e s occur i n samples from cows i n ad-vanced l a c t a t i o n s i n which cases, there are marked changes i n the r e l a t i v e p r o p o r t i o n s of l a c t o s e , p r o t e i n s and ash. Many e a r l y d e t e r m i n a t i o n s of s o l i d s - n o t - f a t were made by a l a c t o -meter (Richmond 1920) which was shown by B a r t l e t t , Golding and Wagstaff (1932) to give r e s u l t s b i a s e d according to the season of the year. Hence the accuracy of some of the e a r l y - 7 -work on v a r i a t i o n i n the s o l i d s - n o t - f a t f r a c t i o n s u f f e r e d . Many m o d i f i c a t i o n s of these methods and other methods are i n use. The advantages they possess and t h e i r drawbacks have been reviewed by L i n g ( 1 9 4 5 ) , Rowland and Scott B l a i r ( 1 9 4 2 ) "and Aschaffenburg and Rook ( 1 9 4 9 ) . The s o l i d s - n o t - f a t f r a c t i o n of m i l k i s estimated from the d i f f e r e n c e between the t o t a l s o l i d s and the f a t content. The s o l i d s - n o t - f a t e s t i m a t i o n v a r i e s , t h e r e f o r e , with any i n -a c c u r a c i e s i n the d e termination of the f a t percentage. T h i s v a r i a t i o n can be avoided by the e s t i m a t i o n of the s o l i d s - n o t -f a t i n the f a t f r e e milk ( B a r t l e t t , 1934 b) V a r i a t i o n due to i n h e r i t e d f a c t o r s : There i s l i m i t e d i n f o r m a t i o n on t h i s s u b j e c t . I t has been observed f o r a long time t h a t the l e v e l of s o l i d s - n o t - f a t f r a c t i o n i n milk from daughters tends to be s i m i l a r to that i n t h e i r mother's milk. Besides t h a t , evidence e x i s t s on the d i f f e r e n c e between breeds, i n d i c a t i n g genetic d i f f e r e n c e s i n the n o n - f a t t y c o n s t i t u e n t s and suggesting a c o r r e l a t i o n between high f a t and high s o l i d s - n o t - f a t . The average v a l u e s of s o l i d s - n o t - f a t f o r a l a r g e number of breeds showing a great v a r i a t i o n i n s o l i d s - n o t - f a t l e v e l s between the breeds were c o l l e c t e d and p u b l i s h e d by B a r t l e t t and Kay ( I 9 5 O ) . S i m i l a r data have been given by Davies ( 1 9 3 9 ) a n d Turner ( 1 9 3 6 ) . The evidence on s o l i d s - n o t - f a t v a r i a t i o n w i t h i n breeds comes from the Danish progeny t e s t s t a t i o n s f o r p r o t e i n and - 8 -from the B r i t i s h s t a t i o n s f o r s o l i d s - n o t - f a t ( B r i t i s h O i l and Cake M i l l s LTD, 1954) showing t h a t d e f i n i t e d i f f e r e n c e s be-tween s i r e s e x i s t . A great deal of i n f o r m a t i o n on the h e r i -t a b i l i t y of s o l i d s - n o t - f a t i s p u b l i s h e d by Bonnier i n Sweden (1949 > 1950) and by Hancock ( 1953) i n i\iew Zealand, who used i d e n t i c a l twins f o r t h e i r experiments. Both workers ob-t a i n e d very high h e r i t a b i l i t y l e v e l s f o r s o l i d s - n o t - f a t , be-tween 80 - 90$« The most recent i n v e s t i g a t i o n (Robertson 1 9 5 6 ) , using 500 daughter-dam p a i r s , presents the h e r i t a b i l i t y l e v e l s f o r s o l i d s - n o t - f a t at around 50%, V a r i a t i o n due to the age of the animal: Information on t h i s subject has been obtained from f i -gures of l a c t a t i o n averages, but the number of separate t e s t s c o n t r i b u t i n g to the l a c t a t i o n average has v a r i e d from one worker to another. Tocher (1928) p u b l i s h e d an equation, Percentage S .JM.F. = 8.7824 - (0.0316 x age) while Gowen (1919) i n the United S t a t e s estimated a negative c o r r e l a t i o n c o e f f i c i e n t between age and s o l i d s - n o t - f a t percent-age, r =-0.219-0.0351 When such p r e c i s e c a l c u l a t i o n s are made the homogeneity of the data must be c o n s i d e r e d . Within most herds the o l d e r cows rep r e s e n t a s e l e c t e d p o p u l a t i o n owing to the c u l l i n g of the poorer y i e l d i n g cows when s t i l l young. T h i s may i n t r o -duce a b i a s i n t o an age r e l a t i o n s h i p and i n v a l i d a t e i t s exact & Age i n years - 9 -measurement. In order to a v o i d such a b i a s the animals s t u -d i e d have to be s e l e c t e d so t h a t t h e i r i d e n t i t y i n each age group i s the same. This was not done i n the two s t u d i e s mentioned above. That the h i g h e s t q u a l i t y milk i s produced by f i r s t c a l -vers has been confirmed by White and Drakeley ( I 9 2 7 ) , B a r t l e t t ( 1 9 3 4 a ) , B a i l e y ( 1 9 5 2 a ) , F l u x et, a l . ( 1 9 5 5 ) and Waite et a l . ( 1 9 5 6 ) . However, Van Rensburg ( I 9 4 6 ) , working i n South A f r i c a p resented data to show t h a t the h i g h e s t q u a l i t y milk was pro-duced by second c a l v e r s . V a r i a t i o n due to the r e l a t i o n s h i p with m i l k y i e l d and  b u t t e r f a t percentage: Gowen ( I 9 I 9 ) and B a i l e y ( 1 9 5 2 a) have both r e p o r t e d small n o n - s i g n i f i c a n t c o r r e l a t i o n c o e f f i c i e n t s between milk y i e l d and s o l i d s - n o t - f a t percentage, t h e i r values being u n a f f e c t e d by the season of c a l v i n g . In both cases, the c o r r e l a t i o n was n e g a t i v e . Robertson ( 1 9 5 6 ) found two d i f f e r e n t c o r r e l a t i o n s , dams' p o s i t i v e and daughters' n e g a t i v e . The c o r r e l a t i o n s be-tween y i e l d and s o l i d s - n o t - f a t expressed as r e g r e s s i o n s show th a t an i n c r e a s e of 1 0 0 g a l . i n y i e l d would cause on the aver-age an i n c r e a s e of 0 . 0 1 5 $ s o l i d s - n o t - f a t i n the dams but a decrease of 0 . 0 2 6 $ i n the daughters. The r e s u l t s , however, do not allow any c o n c l u s i o n as to the g e n e t i c r e l a t i o n between y i e l d and s o l i d s - n o t - f a t , except t h a t the c o r r e l a t i o n , i f any, i s probably very small and n e g a t i v e . - 10 -The r e l a t i o n s h i p between b u t t e r f a t percentage and s o l i d s -n o t - f a t percentage has been examined by many workers: Gowen (1919), Tocher ( 1 9 2 5 ) , C r a n f i e l d , G r i f f i t h s and Lin g ( I 9 2 7 ) , Gaines ( 1 9 2 8 ) , Jacobson ( 1 9 3 6 ) , Provan (1949)> B a i l e y (1952 a) and Waite ( 1 9 5 6 ) . Although the v a l u e s of the c o r r e l a t i o n s r e p o r t e d by these authors have d i f f e r e d , a l l have found them s t a t i s t i c a l l y s i g n i -f i c a n t . The average value would appear to be approximately r = + 0.4* The importance of t h i s c o r r e l a t i o n , as a f a c t o r t e n d i n g to improve the mean l e v e l of s o l i d s - n o t - f a t p e r c e n t -age of milk from a herd where s e l e c t i o n f o r high b u t t e r f a t percentage i s p r a c t i c e d , i s d i s c u s s e d by B a i l e y (1952 a) and Robertson ( 1 9 5 6 ) , who conclude t h a t i t s i n f l u e n c e i s s m a l l . B a i l e y (1952 a) advances data which provide s l i g h t e v i -dence of a change i n the value of these c o r r e l a t i o n s with the advancing age of the animal. As t h i s t rend i n c r e a s e s the p o s i t i v e nature of the r e l a t i o n s h i p , he sp e c u l a t e s on the pos-s i b i l i t y of h e t e r o g e n e i t y i n h i s data caused by the p o s s i b l e i n c l u s i o n of animals s u f f e r i n g from m a s t i t i s ; the i m p l i c a t i o n s of t h i s are d i s c u s s e d . Gaines and Davidson (1923) have shown th a t the value of these r e l a t i o n s h i p s may be changed by s e l e c -t i v e breeding and B a i l e y has con s i d e r e d the p o s s i b i l i t y t h at t h i s f a c t o r may a l s o be i n v o l v e d i n the trends found by him. V a r i a t i o n due to stage of l a c t a t i o n : E a r l y work on t h i s s u b j e c t was done by Drakeley and White (I927) and by B a r t l e t t (1934 b) who used f i g u r e s of s o l i d s -- 11 -n o t - f a t percentages determined by the lactometer method. The shape of l a c t a t i o n curves produced by these workers showed comparatively l i t t l e change throughout l a c t a t i o n . The trends i n d i c a t e d a high l e v e l immediately a f t e r c a l v i n g which r a p i d l y f e l l to a minimum a f t e r s i x weeks f o l l o w e d by a slow r i s e un-t i l the l a c t a t i o n ended. B a r t l e t t ( 1 9 3 4 b ) , when d i s c u s s i n g the r e s u l t s , remarked on the p o s s i b l e e r r o r s i n the shape of h i s curves t h a t might be due to the use of the lactometer method of e s t i m a t i o n . The shape of l a c t a t i o n curves of the same gen e r a l form but showing a much g r e a t e r r i s e from the minimum l e v e l s at the s i x t h week have' been produced by workers using f i g u r e s obtained by more r e l i a b l e techniques: Van Rensburg ( 1 9 4 6 , Davies, Harland, Castor and K e l l n e r ( 1 9 4 7 ) , B a i l e y ( 1 9 5 2 b) and Waite ( 1 9 5 6 ) . The p o s i t i v e g r a d i e n t of the stage of l a c -t a t i o n curves was shown by B a r t l e t t ( 1 9 3 4 b ) , B a i l e y ( 1 9 5 2 b) and Waite ( 1 9 5 6 ) to occur only when animals were pregnant. When animals f a i l e d to conceive the l e v e l s showed no recovery from the minimum l e v e l s t h at were produced one to two months a f t e r c a l v i n g . V a r i a t i o n due to season of the year: Data r e l a t i n g to the seasonal v a r i a t i o n i n the s o l i d s -n o t - f a t content of milk were f i r s t p u b l i s h e d i n England by Richmond ( 1 9 2 0 ) who noted t h a t winter milk was r i c h i n t h i s f r a c t i o n and t h a t summer milk was r e l a t i v e l y poor. Tocher ( I 9 2 5 ) - 12 -observed that the l e v e l of s o l i d s - n o t - f a t was lower i n the three months J u l y , August and September than i n the remaining nine months of the year and s i m i l a r r e s u l t s were r e p o r t e d by Houston and Hale ( 1 9 3 2 ) . B a i l e y ( 1 9 5 2 c) found s t a t i s t i c a l l y s i g n i f i c a n t changes i n l e v e l ; the l e v e l rose to a maximum from A p r i l to May f o l l o w e d by a f a l l from May to J u l y and another r i s e from August to September. Waite ( 1 9 5 6 ) found s o l i d s - n o t - f a t at the h i g h e s t l e v e l i n January and at the lowest i n A p r i l . The r e l a t i o n between weather and the q u a l i t y of milk was d i s c u s s e d by C r a n f i e l d (I93O), who concluded t h a t when weather c o n d i t i o n s are f a v o u r a b l e f o r the growth of g r a s s , the s o l i d s -n o t - f a t content of milk r i s e s . Rowland (1944) l i n k e d the low l e v e l s of s o l i d s - n o t - f a t found i n the months of March and A p r i l with the low plane of n u t r i t i o n u s u a l l y o c c u r r i n g at t h a t time, while B a i l e y (1952 c) r e l a t e d the changes he found with the growth of g r a s s . D i f f e r e n c e s between the seasonal trends found i n v a r i o u s areas of d i f f e r i n g c l i m a t e were examined by Provan ( 1 9 4 9 ) , who found t h a t the g r e a t e s t summer f a l l o ccur-red i n the dry eastern d i s t r i c t s of England, while i n the west of the country the f a l l was o n l y s l i g h t . Seasonal v a r i a t i o n s have been studied i n the U n i t e d States by Ragsdale and Brody ( 1 9 2 2 ) , Hayes (1926) and Weaver and Mathews ( I 9 2 8 ) , who a l l r e p o r t e d low l e v e l s i n the summer months. The opposite t r e n d was found by Davis, Harland, Castor and K e l l n e r ( I 9 4 7 ) while no t r e n d at a l l was found by C a u l f i e l d , Whitnah and Atkinson ( 1 9 3 9 ) . The d i f f e r e n c e s between the - 13 -r e s u l t s appeared to be due to the d i f f e r e n t c l i m a t i c c o n d i -t i o n s of the l o c a t i o n s of the s t u d i e s . Regan and Richardson (1938) found that when the a i r temperature rose above 7 0 ° -0 80 F there was a f a l l i n s o l i d s - n o t - f a t percentage. In South A f r i c a , Van Rensburg ( 1 9 4 6 ) showed t h a t the minimum l e v e l o c c u r r e d i n w i n t e r , t h i s was f o l l o w e d by a peak i n the s p r i n g , a s l i g h t f a l l i n the summer and a r i s e again i n the autumn. Bakalor i n South A f r i c a ( I 9 4 8 ) found a c l o s e r e l a t i o n s h i p between the l e v e l of s o l i d s - n o t - f a t and the r a i n -f a l l . In the province of Milan i n I t a l y , the peak l e v e l of s o l i d s - n o t - f a t occurred i n A p r i l and the minimum l e v e l i n August ( F a b r i s , 1951). There was no suggestion of a second peak o c c u r r i n g i n the autumn. Long term trends; Long term trends i n the l e v e l of s o l i d s - n o t - f a t i n milk were i n v e s t i g a t e d by Provan and Jenkins ( 1 9 4 9 ) > who worked on the r e c o r d s of bulked milks r e c e i v e d at milk f a c t o r i e s . As a r e s u l t of t h i s , t h e i r data represented a very l a r g e number of cows, but as no c o n t r o l could be e x e r c i s e d on t h e i r c h a r a c t e r , i t was not p o s s i b l e to be sure that the changes they found were not due to changes i n breed or age d i s t r i b u t i o n . T h e i r f i n d i n g s i n d i c a t e d t h at the s o l i d s - n o t - f a t i n the milk from the areas with which they were concerned f e l l from a p p r o x i -mately 8 . 9 per cent i n 1 9 2 3 to about 8.6 per cent i n 1 9 4 6 . The r a t e of the d e c l i n e was not constant, being most r a p i d i n - 14 -the years 1 9 3 1 - 1 9 3 3 and again d u r i n g 1939 - 1 9 4 6 . T h e i r f i g u r e s were c a l c u l a t e d as twelve-month moving averages, so they could not s t a t e whether the r a t e of d e c l i n e v a r i e d with the season of the year. The s u b j e c t has a l s o been studied by B a i l e y ( 1 9 5 2 d) u s i n g data f o r Shorthorn f i r s t c a l v e r s of a s i n g l e herd. He a l s o found a d e c l i n e i n l e v e l s from the year 1 9 3 5 to 1 9 4 6 , the f a l l being s t a t i s t i c a l l y s i g n i f i c a n t i n the months of January, February, March, A p r i l and August. In the monthsof May, when cows are fed mainly on grass, he could f i n d no evidence of any decrease. The p o s s i b i l i t y that the d e c l i n e was due to changes i n f e e d i n g p r a c t i c e was d i s c u s s e d . V a r i a t i o n due to plane of n u t r i t i o n : In a planned experiment i n New Zealand, Riddet, Campbell, Mc-Dowall and Cox ( 1 9 4 1 , 1 9 5 4 ) working with cows, were able to show that the s o l i d s - n o t - f a t percentage f e l l with p a r t i a l energy de-p r i v a t i o n , a f a l l of 0 . 3 - 0 . 5 per cent being o b t a i n e d . Another ex-periment r e p o r t e d by Rowland ( 1 9 4 6 ) , produced s i m i l a r r e s u l t s as f a r as energy was concerned. Two very severe d e f i c i e n c i e s of pro-t e i n s , however, produced only a small decrease i n s o l i d s - n o t - f a t percentage (Holmes ejt a l . 1 9 5 6 ) . Davel ( 1 9 4 7 ) noted that low l e v e l s were a s s o c i a t e d with a low plane of n u t r i t i o n . S i m i l a r r e s u l t s were obtained by B a r n i c o a t , Logan and Grant ( 1 9 4 9 ) working with ewes; Provan (1950) considered t h a t low l e v e l s are not a s s o c i a t e d with sub-s tandard rations., for supplements of maize to tftie r ations had - 15 -very l i t t l e e f f e c t . T h i s r e s u l t may perhaps be e x p l a i n e d by the survey s t u d i e s of B a i l e y ( 1 9 5 2 e) who was able to show th a t whereas the l e v e l s rose with i n c r e a s i n g s t a r c h - e q u i v a -l e n t content (dry matter held c o n s t a n t ) , they f e l l with i n -c r e a s i n g dry-matter content ( s t a r c h e q u i v a l e n t held c o n s t a n t ) . I t f o l l o w s t h a t unless the dry-matter content of the r a t i o n i s held constant, an i n c r e a s e i n the s t a r c h e q u i v a l e n t content w i l l not produce i t s f u l l e f f e c t and the change i n s o l i d s - n o t -f a t percentage w i l l be s m a l l . V a r i a t i o n due to hormones; 1. Oestrogens. F o l l e y , Watson and Bottomley ( 1 9 4 1 ) , ex-perimenting with a small number of l a c t a t i n g cows, were .able . to produce under c e r t a i n c o n d i t i o n s a marked r i s e i n s o l i d s -n o t - f a t content f o l l o w i n g the a d m i n i s t r a t i o n of oestrogens. T h i s work has not been repeated using a l a r g e number of a n i -mals. Oestrogens have been found i n B r i t i s h pasture p l a n t s ( B a r t l e t t , F o l l e y , Rowland, Curnow and Simpson, 1948) p a r t i -c u l a r l y during the phase of r e p r o d u c t i v e growth of the p l a n t s (Legg, Curnow and Simpson, 1950). This suggests t h a t the r i s e i n l e v e l s of s o l i d s - n o t - f a t i n milk, that occurs at the s p r i n g f l u s h of g r a s s , may be due to o e s t r o g e n s — l i k e substances. 2. L - T h y r o c i n e . This hormone, produced by the t h y r o i d gland, when administered to a l a c t a t i n g cow produces a small i n c r e a s e i n the s o l i d s - n o t - f a t percentage of the milk. This i n c r e a s e i s the r e s u l t of an i n c r e a s e i n the percentage of l a c t o s e and - 1 6 -a decrease i n the t o t a l p r o t e i n percentage. The subject has been reviewed by B a r t l e t t , Rowland and Thomson ( 1 9 4 9 ) and by B l a x t e r , Reineke, Crampton and Petersen ( 1 9 4 9 ) . V a r i a t i o n due to disease; The o n l y disease f o r which the e f f e c t on the s o l i d s - n o t -f a t of milk has been s t u d i e d i s m a s t i t i s . In t h i s case, while the o v e r a l l e f f e c t on the n a t i o n ' s milk i s probably small (Kay, 1948), there i s no doubt that the e f f e c t on milk from an i n f e c t e d quarter can be very severe, the main charac-t e r i s t i c s being a f a l l i n the l a c t o s e and c a s e i n percentages, a r i s e i n the c h l o r i d e s and g l o b u l i n s and pH. Exhaustive r e -p o r t s on the changes have been p u b l i s h e d by Rowland ( 1 9 3 8 , 1 9 4 2 ) and Rowland and Z e i n - e l - D i n e ( 1 9 3 8 , 1 9 3 9 ) . More r e c e n t l y the e f f e c t on the s o l i d s - n o t - f a t has been examined by McDowall ( 1 9 4 5 ) , Crossman, Dodd, Lee and Heave ( 1 9 5 0 ) , and Weave, P h i l l i p s and M a t t i c k (1952). V a r i a t i o n due to other causes; D i f f e r e n c e s between f i r s t and l a s t drawn milk at m i l k i n g were examined by B a r t l e t t ( 1 9 3 4 b) who concluded t h a t they were s m a l l . V a r i a t i o n from day to day was i n v e s t i g a t e d by B a r t l e t t and Kay ( I 9 5 O ) who found t h a t i t was only s m a l l . A c o e f f i c i e n t of v a r i a t i o n of 2 . 8 per cent has been c a l c u l a t e d . Morning milk u s u a l l y c o n t a i n s a lower l e v e l of s o l i d s -- 17 -n o t - f a t than afternoon m i l k , a mean d i f f e r e n c e of 0 . 0 7 per cent, S.D. 0 . 1 6 per cent has been c a l c u l a t e d . The review above does not d i s c u s s i n d e t a i l two recent s t u d i e s Hansson e_t a l . 1 9 5 0 , Robertson e_t _al. 1 9 5 6 , which the w r i t e r would now l i k e to mention s e p a r a t e l y because of the advanced method by which the s t u d i e s of s o l i d s - n o t - f a t were approached. The two workers represent a group of people who f i r s t s t a r t e d to study the changes i n the l e v e l of s o l i d s - n o t - f a t not as a s i n g l e milk component but as a l a r g e group of v a r i -ous non-fat compounds such as c a s e i n , albumin, g l o b u l i n , other o r g a n i c non-fat compounds, v i t a m i n s , m i n e r a l s , e t c . These i n v e s t i g a t i o n s , and s e v e r a l o t h e r s , have shown t h a t h e r e d i t y has a l a r g e i n f l u e n c e upon the s e c r e t i o n of a number of non-fat compounds and t h a t the l e v e l of s o l i d s - n o t - f a t of milk i s a r e s u l t of a l a r g e v a r i e t y of non-fat substances and the i n t e r r e l a t i o n s h i p between them. ( J a r l 1 9 4 6 , Bonnier and Hansson 1 9 4 6 Hansson 1 9 4 8 a>b, 1 9 4 9 : Winzenried and Wanntorp 1 9 4 8 ; Larson e_t al_. Hansson and Bonnier 1 9 4 9 ; Hansson and S k j e r v o l d 1 9 4 9 ; Hansson e_t al_. 1 9 5 0 Robertson e_t a l . 1 9 5 6 ) The most important p a r t of these non-fat compounds are p r o t e i n s , because of t h e i r fundamental importance i n l i f e p r o c e s s e s . The nitrogeneous c o n s t i t u e n t s of milk may be d i v i d e d i n t o substances of p r o t e i n and n o n - p r o t e i n nature. On an average, 76 per cent of the nitrogeneous c o n s t i t u e n t s comes from c a s e i n , 12 per cent from albumin, 6 per cent from g l o b u l i n and i n - 18 -a d d i t i o n , there may be t r a c e s of lactomucin and l a c t e n i n . The r e s i d u a l 6 per cent comes from n o n - p r o t e i n nitrogeneous substances such as urea, u r i c a c i d , ammonia, c r e a t i n and c r e a t i n i n e . I t i s commonly b e l i e v e d t h a t these l a s t mentioned substances appear i n the milk mainly because of i n f i l t r a t i o n from the b l o o d . The two papers a l r e a d y mentioned above present analyses of milk with r e s p e c t to the t o t a l p r o t e i n , c a s e i n , albumin, n o n - p r o t e i n N, l a c t o s e , f a t and ash, and t h e i r r e l a t i o n s h i p to the stage of l a c t a t i o n (Hansson ejt a_l. 1 9 5 0 , Robertson e t a l . 1 9 5 6 ) and to the season (Robertson et. a l . 1 9 5 6 ) . The f i r s t group of workers analysed the i n t e r r e l a t i o n s h i p of these components g r a p h i c a l l y , the l a t t e r group d i d the same kind of study s t a t i s t i c a l l y . . Their r e s u l t s are summarized i n F i g u r e s 1 , 2 , 3 , and i n Table I I I . TABLE I I I Genetic c o r r e l a t i o n s (Robertson 1 9 5 6 ) Y i e l d Fat S.N.F. Crude P r o t e i n Casein Lacto se Ash Y i e l d Fat S.N.F. Crude P r o t e i n Casein Lactose Ash -0.01 -0.02 0.22 0.05 -0.16 -0.10 0 . 4 6 0 . 4 8 0 . 5 6 0 . 3 7 0 . 4 2 0 . 9 4 0.82 0 . 6 7 0 . 3 2 O . 9 6 0 . 4 1 0 . 4 1 0 . 1 0 - 0 . 2 4 - 0 . 8 6 - 19 -- 20 -THE HISTORY OF THE U.B.C. DAIRY HERD The herd of A y r s h i r e cows maintained by The U n i v e r s i t y of B r i t i s h Columbia was used f o r t h i s experiment. The herd has e x i s t e d p r i m a r i l y to provide milk and animals f o r r e s e a r c h purposes. I t was e s t a b l i s h e d i n 1929 ' , when 23 pedigree A y r s h i r e cows and one b u l l were imported from S c o t l a n d . The present herd i s a product of s e l e c t i v e l i n e breeding from three out s t a n d i n g cows which were i n c l u d e d i n the imported group. Name Age Type L i f e Fat % at death milk prod.  Rainton R o s a l i n d 5 t h 18 E x c e l l e n t 4 1 5 0 , 0 0 0 l b s . 4 . 2 3 Ardgowan Gladness v 2 n d 16 E x c e l l e n t 1 2 0 , 0 0 0 l b s . 4 . 2 0 Lochinch L a s s i e 20 E x c e l l e n t 1 2 5 , 0 0 0 l b s . 4 . 1 0 The aim of the breeding p o l i c y was to b u i l d up a home-bred herd, with good m i l k i n g q u a l i t i e s , of good breed type, with good udders and f r e e from d i s e a s e s . The p u r s u i t of these i d e a l s has been attended with c e r t a i n handicaps. Perhaps the most s e r i o u s of the d i f f i c u l t i e s encountered was an outbreak of contagious a b o r t i o n mainly i n the years 1 9 3 6 and 1 9 3 7 . This had a s e r i o u s e f f e c t on s e l e c t i o n p r a c t i c e f o r s e v e r a l y e a r s . By t h i s , the c o n t i n u i t y of the herd breeding p o l i c y was s e r i o u s l y i n t e r r u p t e d and the q u a l i t y of the herd d e c l i n e d c o n s i d e r a b l y . Since then, a l l c a l v e s , h e i f e r s and cows have been v a c c i n a t e d to prevent f u r t h e r outbreaks. 4 Not c l a s s i f i e d - but many times grand champion. - 21 -M a s t i t i s i s another d i s e a s e , which o c c a s i o n a l l y has been c r e a t i n g d i f f i c u l t problems to the management. I t has happened a few times d u r i n g the 28 years t h a t the stage of m a s t i t i s reached such a l e v e l where the a f f e c t e d cows had to r e c e i v e s p e c i a l a t t e n t i o n although i t r a r e l y caused any c u l l i n g or d i s -p o s a l of breeding stock. In 1954 lungworm spread through the herd and i t s presence caused changes i n the management p r a c t i c e s f o r the summer season 1 9 5 5 , a l l animals being kept o f f the- farm f i e l d s . During the l a s t two years the.herd has been used f o r experimental s t u d i e s on the problem of pasture versus mechanized f e e d i n g . In the s p r i n g of 1 9 5 6 a new l o a f i n g barn was c o n s t r u c t e d adjacent to the stanchion barn, and at t h i s same time, through donations of v a r i o u s breeders i n the Fraser V a l l e y , a herd of H o l s t e i n s was a c q u i r e d . In the f a l l of 1 9 5 6 the whole m i l k i n g herd was s p l i t i n t o two groups which have been kept apart through the winter of 1956 - 1 9 5 7 , one group i n s i d e and the other o u t s i d e . Recovery from the aftermath of the Bang's di s e a s e outbreak of 1 9 3 6 - 1 9 3 7 was f a i r l y complete about 1 9 4 2 . At t h a t time p r o d u c t i o n was at about breed average l e v e l s and b u t t e r f a t t e s t was low at 3 * 7 0 $ . By I 9 5 4 , an i n t e r v a l of 12 ye a r s , p r o d u c t i o n had r i s e n to about o n e - t h i r d above breed average and b u t t e r f a t t e s t had advanced to an average of 4«80$. P r o d u c t i o n l e v e l s and t e s t have remained f a i r l y constant since 1 9 5 4 « - 22 -Because of the high average b u t t e r f a t t e s t and because approximately o n e - t h i r d of the cows t e s t over 5%, i t was f e l t t h a t t h i s U n i v e r s i t y herd o f f e r e d s p e c i a l o p p o r t u n i t i e s f o r s t u d i e s of s o l i d s - n o t - f a t . EXPERIMENTAL Animals used and method of milk sampling T h i s study was scheduled f o r two s u c c e s s i v e winter seasons 1 9 5 5 - 1 9 5 6 and 1 9 5 6 - 1 9 5 7 ' Twenty A y r s h i r e cows were t e s t e d i n the f i r s t year and eighteen A y r s h i r e s and ten H o l s t e i n s d u r i n g the second year. The a v a i l a b l e A y r s h i r e cows were put i n four groups, the progenies of four b u l l s , White Cockade, S p i t f i r e , Gold Standard and Commodore. The p l a n n i n g of t h i s experiment met with some d i f f i c u l t i e s r i g h t at the b e g i n n i n g . The l i m i t e d number of progenies f o r each p a r t i c u l a r b u l l and the short p e r i o d of milk t e s t i n g made i t unavoidable that there be some v a r i a t i o n i n age and i n stage of l a c t a t i o n . C o r r e c t i o n s f o r these v a r i a t i o n s were made as a p p r o p r i a t e l y as p o s s i b l e . The experiment i n v o l v e d the a n a l y s i s of 480 samples of m i l k . The sampling s t a r t e d i n November 1 9 5 5 and continued to February 1 9 5 6 . The second p e r i o d of sampling f e l l between November 1 9 5 6 to January 1 9 5 7 . The samples taken were composite of one evening sample followed by another from the next morning's m i l k . The m i l k i n g was done twice a day at 5 a.m. and 4 p.m. A l l cows were machine milked and hand s t r i p p e d . - 23 -Management of the herd During the winter season 1955 - 1956 the whole herd was kept under the same management c o n d i t i o n s . The cows r e c e i v e d about 1.5 l b . of medium q u a l i t y red c l o v e r - orchard grass hay per 100 l b s . of body weight; the same amount of red c l o v e r -orchard grass s i l a g e and 1 l b . of d a i r y g r a i n mixture per 2 l b s . of m i l k . The f o l l o w i n g year 1956 - 1957 the environmental con-d i t i o n s v a r i e d c o n s i d e r a b l y with r e s p e c t to the p r e v i o u s season and a l s o w i t h i n the season. As has been mentioned a l r e a d y , the herd was d i v i d e d i n t o two groups, one of them being kept i n s i d e and the other one ou t s i d e i n the open l o a f i n g barn. The dry roughage fed to the cows was the same q u a l i t y f o r both groups, medium q u a l i t y red c l o v e r , orchard grass or timothy a l f a l f a hay mi x t u r e s . The cows i n s i d e were g e t t i n g 1 l b . of hay per 100 l b s . of body weight; the o u t s i d e group was r e c e i v i n g only h a l f as much. The r a t i o n s d i f f e r e d a l s o i n the nature and amount of s i l a g e . The group of cows kept i n s i d e was g e t t i n g 3 l b s . of red c l o v e r orchard grass s i l a g e per 100 l b s . of body weight from a roofed v e r t i c a l s i l o i n c o n t r a s t to the o u t s i d e group, which had f r e e access to peavine s i l a g e s t o r e d i n an open h o r i z o n t a l s i l o . The a n a l y s i s of these feeds i s shown i n Table IV. - 24 -TABLE IV Chemical composition of roughage Feed Dry P r o t e i n Ash Ether Crude Nit r o g e n Matter E x t r a c t F i b r e E x t r a c t Hay 89.0 9.15 7.22 1.25 34.2 37.22 Out si d e S i l a g e 25.62 3.40 2.67 0.78 9.05 9-76 In side S i l a g e 30.88 4.05 1.95 1.04 11.27 12.55 The r a t i o n of g r a i n fed the second year was about 1 l b . per 3 l b s . of milk, a smaller amount than that of the previous year. Laboratory procedures f o r b u t t e r f a t and s o l i d s - n o t - f a t determi-n a t i o n The milk samples were warmed to about 25° C, g e n t l y i n -v e r t e d s e v e r a l times to r e d i s p e r s e the f a t . A l i q u o t s were then taken f o r the d e t e r m i n a t i o n of f a t and t o t a l s o l i d s . A l l t e s t s < were done i n d u p l i c a t e . Time d i d not permit both analyses to be done i n one day; on the average i t r e q u i r e d three days to accomplish the whole t e s t . T o t a l s o l i d s were measured g r a v i -m e t r i c a l l y . About 5 g of m i l k were weighed i n t o a small aluminum d i s h , and evaporated to apparent dryness i n an oven at 100° C, cooled i n a d e s i c c a t o r and weighed. S o l i d s - n o t - f a t were determined by deducting the value f o r f a t from the value f o r t o t a l s o l i d s . ANALYTICAL METHODS OF HERITABILITY ESTIMATES T r a i t s i n farm l i v e s t o c k and In other farm animals are - 25 -f r e q u e n t l y d e s c r i b e d as " h i g h l y " or "moderately" h e r i t a b l e depending on how c l o s e l y parents and o f f s p r i n g , f u l l s i b s , or other c l o s e r e l a t i v e s resemble each other. H e r i t a b i l i t y i s important to the breeder because i t r e p r e s e n t s the p r o p o r t i o n of the gain which i s t r a n s m i t t e d to the o f f s p r i n g through s e l e c t e d p a r e n t s , and i s g e n e r a l l y u s e f u l i n e s t i m a t i n g probable g e n e t i c improvement (Lush 1935). In a d d i t i o n , estimates of h e r i t a b i l i t y are e s s e n t i a l i n pl a n n i n g e f f i c i e n t breeding systems (Wright 1939) a n d i n determining the r e l a t i v e emphasis due each of s e v e r a l t r a i t s when breeding animals are s e l e c t e d (Hazel 1943)-Adequate numbers of r e l a t e d animals are needed f o r determi-ning the h e r i t a b i l i t y of any t r a i t . The most common m a t e r i a l s used f o r t h i s purpose are monozygotic twins which are r e l a t e d 100$ or f u l l s i s t e r s or b r o t h e r s ( f u l l s i b s ) having both parents the same and being r e l a t e d to each other 50$, or f i n a l l y groups of h a l f s i s t e r s or h a l f b r o t h e r s ( h a l f s i b s ) having only one parent i n common and being r e l a t e d to each other 25$. The p r i n c i p a l approach to t h i s problem i s i n a l l methods the same. H e r i t a b i l i t y i s expressed as a percentage i n d i c a t i n g the p a r t of the phenotypic v a r i a n c e of a t r a i t due to the g e n e t i c a l make up. I t can be expressed by a formula G G + E where G » g e n e t i c a l v a r i a n c e E a enironmental v a r i a n c e G + E - t o t a l phenotypic v a r i a n c e - 26 -Monozygotic twins f o r t h i s kind of work are very u s e f u l , but have a c e r t a i n disadvantage to the other methods because the h e r i t a b i l i t y c o e f f i c i e n t r e l a t e s to the t o t a l g e n e t i c v a r i -ance i n c l u d i n g a l l the e p i s t a t i c and dominant, as w e l l as a d d i t i v e , gene e f f e c t s (Hancock 1953). The resemblance between parents and o f f s p r i n g i s the most widely u s e f u l method. There are two ways of determining h e r i -t a b i l i t y ; e i t h e r u s i n g daughter-dam p a i r s or a number of s i r e progeny groups. In the f i r s t case, the h e r i t a b i l i t y e s t i m a t i o n i s sometimes c a l l e d the daughter-dam c o r r e l a t i o n method. In a s e r i e s of daughter-dam p a i r s , each daughter's performance i s an i n d i c a t o r of her dam's breeding value or, i n other words, h e r i t a b i l i t y . I f performance was an accurate guide to breeding value ( i . e . i f the h e r i t a b i l i t y was 100$) then the dam-daughter r e g r e s s i o n would be one-half because o n l y one-half of the daughter's genes come from the dam. In g e n e r a l terms, the dam-daughter r e g r e s s i o n i s equal to one-half of the h e r i t a b i l i t y . I f the v a r i a n c e w i t h i n the dam and daughter groups i s equal, then the r e g r e s s i o n of a daughter's performance on t h a t of her dam i s equal to the c o r -r e l a t i o n between them. H e r i t a b i l i t y , t h e r e f o r e , i s determined by simply doubling the c o r r e l a t i o n c o e f f i c i e n t . The second method was used i n t h i s study. The procedure i s d e s c r i b e d i n d e t a i l i n the next s e c t i o n . Four daughter groups of four b u l l s were s e l e c t e d from the U n i v e r s i t y herd. U n f o r t u n a t e l y , as p r e v i o u s l y mentioned, i t was not p o s s i b l e to . 27 -have a l l groups of the same s i z e . (see Tables XI and XII) The m a t e r i a l used was somewhat unusual. I t c o n s i s t e d of a number of cows, part of one l a c t a t i o n each, with a c o n s i d e r a b l e v a r i a t i o n i n age and stage of l a c t a t i o n . In c a r r y i n g out a g e n e t ic a n a l y s i s , i t i s d e s i r a b l e to r e -move at the s t a r t as many obvious non-genetic v a r i a t i o n s as pos-s i b l e . R e a l i z i n g t h i s , i t was necessary to c o n s i d e r f o u r main f a c t o r s - the age of cows, stage of l a c t a t i o n , m a s t i t i s outbreak and d i f f e r e n t f e e d i n g p r a c t i c e s i n the winter season 1 9 5 6 - 1 9 5 7 . The f i r s t step was to c o r r e c t the v a l u e s of s o l i d s - n o t - f a t f o r stage of l a c t a t i o n and age. The e f f e c t s of these f a c t o r s have been d i s c u s s e d i n the l i t e r a t u r e review and are shown i n F i g u r e s 4 and 5 . The.Figure 6 and Tables XVIII, XIX give the l a c t a t i o n stages and age d i s t r i b u t i o n s r e s p e c t i v e l y . In Figure 6 the blue l i n e s i n d i c a t e the l a c t a t i o n p e r i o d s with the c a l v i n g dates at the l e f t ends and the d r y i n g o f f dates at the r i g h t ends of the l i n e s . The dates on the blue l i n e s between the two end p o i n t s i n d i c a t e the breeding dates to show i f any i n f l u e n c e o f pregnancy should e x i s t . The p e r i o d of milk t e s t s i s l o c a t e d between the two yellow l i n e s . The d e c l i n e i n s o l i d s - n o t - f a t l e v e l s d u r i n g the f i r s t 45 days of l a c t a t i o n and the r i s e at the end, as found by other workers (see F i g u r e 4 ) were not r e v e a l e d by the data of t h i s experiment. I t would appear that the e f f e c t of season counter-acted t h a t of l a c t a t i o n and hence no c o r r e c t i o n s f o r e f f e c t of - 28 -F i g u r e 4 I n f l u e n c e of Stage of L a c t a t i o n on S o l i d s - n o t - f a t •P cd «H I -P o c I c o •n •H rH O cn -P a a> o u CD CU D a v i s , (1947) Jersey-a l l e y (1952) S h o r t h o r n b a r t l e t t (1934) Mixed Herd rfaite(1956) A y r s h i r e -p ct) -p O G I CO T> •H rH O ro -P C 0) o CD a, 2 3 4 5 6 Months a f t e r c a l v i n g F i g u r e 5 I n f l u e n c e of Age on S o l i d s - n o t - f a t 8 B a i l e y ( 1 9 5 2 ) S h o r t h o r n White (1927) A y r s h i r e Waite (1956) A y r s h i r e 1 2 3 4 5 6 7 8 9 10 L a c t a t i o n s - F i g u r e 6 Stages of L a c t a t i o n Cow May- June J u l y Aug. Sep. Oct , Iv ov Dec. Jan. Feb. Mar . Apr. May June J u l y Aug. Sep . Oct • i Amber A n i t a A l i i son Barone s s 3erni ce B e t t y Brenda Brownie Cathy Cherry Crocus C r y s t a l C e c e l i a Diana Dorothy Omega P a t r i c i a Rennie R i t a S h e i l a Temptress V a n i t y - 30 -l a c t a t i o n were p o s s i b l e . The strong e f f e c t of season i s shown c l e a r l y i n Figure 7» The c o r r e c t i o n i n v a r i a n c e due to age was c a l c u l a t e d u s i n g the c o r r e c t i o n s d e r i v e d from the r e s u l t s of s e v e r a l workers, some of them shown i n Figure 5« The c o r r e c t i o n s were 0.1$ f o r f i r s t l a c t a t i o n and 0.05$ f o r each of the next four f o l l o w i n g l a c t a t i o n s . I t means t h a t the s o l i d s - r i o t - f a t values were changed to the e q u i v a l e n t of mature animals with f i v e l a c t a t i o n s completed. The procedure of the c a l c u l a t i o n i s shown i n Table XI. I t was intended t o use data from both winter-seasons 1955 - 1956 and 1956 - 1957, expecting t h a t environmental con-d i t i o n s would be reasonably constant. This would have provided l a r g e r progeny groups. But the unexpected outbreak of m a s t i t i s i n 1956 - 1957 changed the plans c o n s i d e r a b l y and i t was ne-c e s s a r y to exclude from the a n a l y s i s the animals of the season 1956 - 1957 (except three) and to use the data of the previous season 1955 - 1956, o n l y . The r e s u l t s of the two seasons were s t u d i e d s e p a r a t e l y . A n a l y t i c a l method used The l e a d i n g r e f e r e n c e s f o r t h i s study were works of Hazel and T e r r i l (1951) and King and Henderson (1954). The t o t a l v a r i a n c e of the progenies was separated i n t o components as f o l l o w s . B component r e p r e s e n t s the v a r i a n c e between cows by the same s i r e , and A the a d d i t i o n a l v a r i a n c e - 31 -between cows by d i f f e r e n t s i r e s , hence a l l cows have the v a r i a n c e A • B. Table V shows the r e l a t i o n s between the components of v a r i a n c e and the g e n e t i c (G) and environmental (E) v a r i a n c e f o r two systems of.mating. The g e n e t i c v a r i a n c e (G) r e p r e s e n t s t h a t due to the e f f e c t s of genes which combine a d d i t i v e l y ac-c o r d i n g to the m u l t i p l e f a c t o r h y p o t h e s i s , and the environmental v a r i a n c e (E) r e p r e s e n t s the combination of environment, dominance, and e p i s t a s i s . In non-Inbred - p o p u l a t i o n s , h a l f s i b s each r e -c e i v e a sample h a l f of t h e i r s i r e ' s i n h e r i t a n c e , hence A » 5 G TABLE V R e l a t i o n s between components of v a r i a n c e and the  genetic and environmental v a r i a n c e f o r two systems of mating Source Component Random p o p u l a t i o n U.B.C. p o p u l a t i o n Variance A £ G £ G - XG of o f f s p r i n g B £ G • E G • XG) • E A + B G + E G + E Because the U.B.C. herd p o p u l a t i o n i s p a r t i a l l y i n b r e d and a l l i n d i v i d u a l s are r e l a t e d to each other, the a n a l y s i s of the components of v a r i a n c e had to be done as f o r a non-random mating p o p u l a t i o n , and c e r t a i n adjustments'were necessary to e l i m i n a t e the d e v i a t i o n s from random mating. - 32 -Lush (1940) suggested s e v e r a l methods of e s t i m a t i n g h e r i t a b i l i t y , of which one, the h a l f - s i b c o r r e l a t i o n , i s best adapted to the present data. The s t a t i s t i c s are e q u i v a l e n t to A i n the symbols of Table V. In non-inbred p o p u l a t i o n s A + B they must be m u l t i p l i e d by 4 to provide estimates of h e r i t a b i -l i t y as shown i n Table VI. TABLE VI Formulas f o r estimates of h e r i t a b i l i t y f o r two systems of mating Method of e s t i m a t i o n Non-inbred p o p u l a t i o n U.B.C. herd H a l f - s i b c o r r e l a t i o n 4 A 4 A x C.F« A + B A + B As shown i n Table V the A component of v a r i a n c e i n an in b r e d p o p u l a t i o n , as the U.B.C. herd, i s s m a l l e r , and component B i s l a r g e r than i n a random mating p o p u l a t i o n , t h e r e f o r e the r a t i o A has to be m u l t i p l i e d by 4 times c o r r e c t i o n f a c t o r A + B (C . F . ) . The c a l c u l a t i o n of C.F. i s shown i n the next s e c t i o n . Because of d i f f e r e n c e i n s i z e of progeny groups used i n t h i s experiment, the c o e f f i c i e n t s of the v a r i a n c e components had to be used. To i s o l a t e the components of v a r i a n c e and to determine the c o e f f i c i e n t s , the work of King and Henderson (1954) was taken as an example. - 33 -Variance components a n a l y s i s : . ( S t a t i s t i c a l Model) In the f o l l o w i n g s t a t i s t i c a l model every i n d i v i d u a l datum i s expressed as a l i n e a r f u n c t i o n of c e r t a i n parameters and random v a r i a b l e s . l i j k = u + s - r C + e where Y i s the r e c o r d of k progeny of the j dam mated to the i ^ s i r e . The t o t a l number of o b s e r v a t i o n s equals W. In t h i s study, the l i m i t e d number of s e l e c t e d cows r e s u l t e d i n s i m p l i f i c a t i o n of the model. The i n d i v i d u a l components of the v a r i a n c e are on l y u, s and c, where u i s the p o p u l a t i o n mean, s = s i r e e f f e c t and c = cow e f f e c t . Y i s then the r e c o r d of the j cow and the i s i r e . The assumptions i n the model are t h a t Y i s d i s t r i b u t e d with expected values (E - average value i n repeated sampling) of the e f f e c t s as f o l l o w s : an o v e r a l l mean 2 2 2 2 equal to u and Es = Ec = 0 with Es = co » Ec = I t i s s c f u r t h e r assumed t h a t a l l c o v a r i a n c e s among the elements equal z e r o . In other words, the elements are u n c o r r e l a t e d . The a n a l y s i s of vari a n c e model i s presented i n Table V I I . TABLE VII A n a l y s i s of v a r i a n c e model Source of V a r i a t i o n d.f. Sum of squares T o t a l ( u n c o r r e c t e d ) N T C o r r e c t i o n Term 1 C T . T o t a l ( c o r r e c t e d ) N - l T-C.T. Among s i r e s ( c o r r e c t e d ) S - l H-C.T. - 34 -The c o e f f i c i e n t of the v a r i a n c e components which i s needed f o r the c o r r e c t i o n term c a l c u l a t i o n was d e r i v e d from the formula N where c, , c 0 > c 0 , and c are numbers of progenies of the s i r e s ± 2 3 4 s l > 32' s3 a n c* s4 r e s P e c " t i v e l y . Table VIII g i v e s the c o e f f i c i e n t s of the v a r i a n c e components i n the expected sum of squares. TABLE VIII C o e f f i c i e n t s of the v a r i a n c e components i n  the expected sum of squares Sum of squares 2 n 2 s 2 c T N N iM H M S C T . N k 1 ANALYSIS OF DATA AiMD RESULTS The r e s u l t s of a l l t e s t s are presented i n the appendices ( I , I I , I I I ) . The h a l f - s i b c o r r e l a t i o n f o r s o l i d s - n o t - f a t The s o l i d s - n o t - f a t v a l u e s used i n these c a l c u l a t i o n s are i n Table XI. Using the procedure o u t l i n e d i n the s t a t i s t i c a l model the f o l l o w i n g r e s u l t s were obtained: - 35 -TABLE IX C o e f f i c i e n t s of the varia n c e component s i n the expected sum of square s Sum of squares n 2 S2 c 2 T 22 22 22 H 22 22 4 C T . 22 6 1 Where N = 22, T o t a l number of o b s e r v a t i o n s s = ky T o t a l number of s i r e groups k = 6, C o e f f i c i e n t f o r s i r e e f f e c t , which was d e r i v e d from: k ss 82+ 5 2+ 5 2* 4 2 a 6 22 The next step was the c a l c u l a t i o n of the expected sums of squares. U n c o r r e c t e d : Corrected: T cs 22n 2 + . 22s 2 • 22c 2 T«*CT. = 16s 2 + 21c 2 H r 22n 2 + 22s 2 + 4 c 2 H-C.T. = 1 6 s 2 + 3 c 2 2 2 2 C T . = 22n + 6s + l c TABLE X The complete a n a l y s i s of v a r i a n c e and v a r i a n c e component s Source of v a r i a t i o n d.f. Symbol Sum of Expected sum squares of squares T o t a l (uncorrected) C o r r e c t i o n Term T o t a l ( c o r r e c t e d ) Among s i r e s (uncorrected) Among s i r e s ( c o r r e c t e d ) 22 T 1921 . 5286 1 C .T. 1920 .3041 21 T -CT 1 .2245 4 H 1920 .4992 3 H -CI 0 .1951 I 6 s 2 + 2 1 c 2 >L22S2+ 4c? I6s 2+ 3c - 36 -By s u b t r a c t i n g the c o r r e c t e d v a r i a t i o n among s i r e s from the t o t a l c o r r e c t e d v a r i a t i o n ( i n the form of sum of squares) one component of var i a n c e i s i s o l a t e d . 2 2 16s,, + 21c 2 -16s * 3c 18c - 2 T h e r e f o r e : 18c^ s 1.0294 c = 0.0572 2 S u b s t i t u t i n g c i n t o the c o r r e c t e d t o t a l sum of squares the other component of the variance i s determined: , 2 1.2245 = 16s + 1.2012 s 2 = 0.0014 s 2 = J- = 0.0014 c 2 = <~ - 0.0572 s ~- c S u b s t i t u t i n g these components of the var i a n c e i n t o the formula f o r h a l f - s i b c o r r e l a t i o n c o e f f i c i e n t r - s 2 + 2 ^ s ®c r - 0.0014 0.0586 r = 0.0238 The h a l f - s i b c o r r e l a t i o n c o e f f i c i e n t ( r ) f o r s o l i d s - n o t - f a t t h e r e f o r e , i s 0.0238. TABLE XI S o l i d s - n o t - f a t values and t h e i r c o r r e c t i o n s f o r age Name Test L a c t a t i o n C o r r e c t i o n C o r r e c t e d value f o r age value  S i r e White Cockade: Brenda 9 - 7 4 2nd -0.20 9.54 Brownie 9.40 2nd -0.20 9.20 Cro cus 9 .61 1st - 0 . 3 0 9 . 3 1 C r y s t a l 9 - 6 7 1st -0 . 3 0 9 . 3 7 P a t r i c i a 9.21 7th 0.00 9.21 Rennie 9 - 5 0 6th 0.00 9-50 R i t a 8.97 6th 0.00 8.97 S h e i l a 9.08 5th -0 . 0 5 9 - 0 3 S i r e Commodore: A l l i s o n 9.84 2nd -0.20 9-64 Amber 9.88 3rd -0 . 15 9 - 7 3 A n i t a 9 . 2 4 3rd -0 . 1 5 9.O9 Temptre s s 9 . 2 5 4th -0.10 9.15 Vanity- 10.00 3rd -0 . 15 9-85 S i r e Gold Standard: Bar one s s 9 . 4 9 1st - 0 . 3 0 9.19 B e r n i c e 9 . 9 5 1st -0 . 3 0 9-65 B e t t y 9.69 1st -0 . 3 0 9-39 Cathy 9 - 6 6 1st -0 . 3 0 9-36 S i r e S p i t f i r e C e c e l i a 9.84 1st -0 . 3 0 9.54 Cherry 9.51 1st -0 . 3 0 9.21 Diana 9 . 4 0 1st -0 . 3 0 9.10 Dorothy 9 . 4 2 1st -0 . 3 0 9.12 Omega 9 -39 7th 0.00 9-39 - 38 -The h a l f - s i b c o r r e l a t i o n f o r b u t t e r f a t E x a c t l y the same a n a l y s i s was used f o r the de t e r m i n a t i o n of h e r i t a b i l i t y of the b u t t e r f a t . The f o l l o w i n g set of data was used f o r the c a l c u l a t i o n : TABLE XII B u t t e r f a t percentages S i r e s White Cockade Commodore Golden Standard S p i t f i r e Rennie 4-23 A n i t a 5.03 Bernice 5 . 7 1 C e c e l i a 2. 95 C r y s t a l 4.28 A l l i s o n 5.43 Betty 4.89 Cherry 4. 41 Crocus 4 . 9 1 Amber 5.79 Baroness 5 .52 Dorothy 4. 13 P a t r i c i a 4 . 2 9 Temptre s s 4.26 Cathy 5.33 Diana 4- 81 R i t a 4 . 7 0 V a n i t y 6.29 Omega 4. 68 S h e i l a 4.08 Brownie 4.07 Brenda 4*46 TABLE XIII The complete a n a l y s i s of v a r i a n c e and v a r i a n c e components: Sources of v a r i a t i o n d.f. Symbol Sum of square s Expected sums of squares T o t a l ( uncorrected) C o r r e c t i o n term 22 1 T C T . 505.5745 494.0028 2 2 2 22n +22s +22c 2 2 2 22n + 6s • 1c T o t a l ( c o r r e c t e d ) 21 T-C.T. 11 . 5 7 6 7 I 6 s 2 + 2 l c 2 Among s i r e s ( uncorrected) 4 H 5 0 0 . 0 0 5 6 22n +22s 24 4 c 2 Among s i r e s ( c o r r e c t e d ) 3 H-C.T. 6.0028 • L 2 2 16s + 3c r-2 2 c = S = 0.3334 c 2 2 s = £5 = s 0.2859 r - 0.0461 - 39 -The h a l f - s i b c o r r e l a t i o n c o e f f i c i e n t ( r ) for b u t t e r f a t t h e r e f o r e , i s 0 . 0 4 6 1 . H e r i t a b i l i t y estimates f o r s o l i d s - n o t - f a t and f a t In the case of a random mating p o p u l a t i o n , these cor-r e l a t i o n c o e f f i c i e n t s would be m u l t i p l i e d by 4 to determine the h e r i t a b i l i t y l e v e l . Because the herd which t h i s experiment was d e a l i n g with i s i n b r e d and has an above average r e l a t i o n -ship among the cows-, a c o r r e c t i o n f a c t o r had to be c a l c u l a t e d . For t h i s purpose the covariance chart was used. The pedigrees of a l l twenty-two cows which were t e s t e d i n t h i s work were t r a c e d back to t h e i r three E x c e l l e n t common anc e s t o r s which e s t a b l i s h e d t h i s herd, and which are l i s t e d at the beginning of t h i s paper. To accomplish t h i s , 66 cows and 7 b u l l s were l i n e d 1. up i n successive order from 1929 to date along two s i d e s of the covariance c h a r t , as i s shown i n the model on page 7 7 . In the column with the heading "Parents", the parents of each i n d i v i d u a l are l i s t e d by number r e f e r e n c e . They are always l o c a t e d on the sc a l e above the o f f s p r i n g . Next column to the r i g h t i s designated "1 + F" f o r u n i t y p l u s the c o e f f i c i e n t s of i n b r e e d i n g . The r e s t of the covariance chart i s f i l l e d out with covariances of each i n d i v i d u a l i n r e l a t i o n to each other i n d i v i d u a l . To f i l l out the covariance chart the procedure i s as f o l l o w s . The order of the c a l c u l a t i o n s goes from Number 1 (the f i r s t animal on the s c a l e ) down to Number 73 (the l a s t animal on the s c a l e ) . - 40 -1. An i n b r e e d i n g c o e f f i c i e n t (F) of an animal equals one-half the covariance between i t s p a r e n t s . 2. To f i l l i n the covariance c e l l s , the covariance between two i n d i v i d u a l s i s h a l f the sum of the cov a r i a n c e s between the olde r i n d i v i d u a l and the parents of the younger one. Examples: 1 + F f o r #7 i s 1 • ^ covariance between #5 and #2, i . e . 1.00 + 0.00 •- 1.000 The covariance between #4 and #7 i s \ the covariance between #4 and #5, and #4 and #2, i . e . \ (0 .00 • 0.50) = 0.250 When the covariance c h a r t was completed, i t was ready to be used f o r quick c a l c u l a t i o n of the r e l a t i o n s h i p c o e f f i c i e n t (R) between any two animals (x and y) l i s t e d i n the cha r t by s u b s t i t u t i n g the covariance (CV) i n t o the formula f o r the r e l a t i o n s h i p c o e f f i c i e n t 4 CV Xy w y Table XIV g i v e s the four progeny groups i n Column C, s i r e s i n Column A and dams i n Column B. The four progeny groups of Column C are s e p a r a t e l y i d e n t i f i e d as D,E,F and G. With the help of the covariance c h a r t the average r e l a t i o n -ship w i t h i n each of the f o l l o w i n g groups was determined. ft Wright's r e l a t i o n s h i p c o e f f i c i e n t (1921) - 41 -TABLE XIV Members of progeny groups and t h e i r parents A B C S i r e s Dams O f f s p r i n g White Cockade T r i x i e T r i p o l i T u l i p Trudy lona O l i v i a L u c r e t i a Laura Brownie Brenda Crocus C r y s t a l P a t r i c i a R i t a Rennie S h e i l a D Commodore Quaker Penelope Que st Penelope Myra A n i t a A l i i son Amber Temptress Vani t y E Gold Standard V i r t u e V a l e n c i a Pamela S i l v e r t o e s Bernice Betty Baroness Cathy F S p i t f i r e S h e i l a A l i c e T i s h S i l v e r t o e s L a s s i e C e c e l i a Cherry Dorothy Diana Omega G TABLE XV Average r e l a t i o n s h i p s of groups A, B , D ,E , F and G Group A B D E F G Average r e l a t i o n s h i p 0.212 0.219 0.379 0.410 0.365 O.389 - 4 2 -From Table XV we can see that the average r e l a t i o n s h i p among the s i r e s (A) i s 2 1 . 2 $ and among the dams (B) 2 1 . 9 $ . Because both samples o r i g i n a t e from the same p o p u l a t i o n , i t was assumed, t h a t a l s o the average r e l a t i o n s h i p between the s i r e s and dams together i s around 2 1 $ . Groups D,E,F and G r epresent f o u r groups of h a l f - s i b s . I f they had been a product of a random mating p o p u l a t i o n , the average r e l a t i o n s h i p w i t h i n each group would be 2 5 $ and the f o u r c o e f f i c i e n t s would, of course, average 2 5 $ . In these data, however, the four c o e f f i c i e n t s have an average value of 3 8 . 6 $ which means t h a t the r e l a t i o n s h i p averages 1 3 . 6 percent-age p o i n t s more than f o r groups of h a l f - s i b s from a random mating p o p u l a t i o n . T h i s i s a 5 4 . 4 $ i n c r e a s e . The q u e s t i o n a r i s e s , what would be the average r e l a t i o n -ship of the o f f s p r i n g , i f the parents (A and B), having the average r e l a t i o n s h i p of 2 1 $ , were mated at random. Using the covariance chart the r e l a t i o n s h i p was c a l c u l a t e d . I f the same parents (A and B) were mated at random, t h e i r progeny would have the average r e l a t i o n s h i p ( 0 . 4 0 8 ) about 4 1 $ . Because the progenies D,E,F and G have an average r e l a t i o n s h i p of O . 3 8 6 , t h e i r parents were not mated at random. Thus the h e r i t a b i l i t y c a l c u l a t i o n based on these data r e q u i r e s the use of the c o r r e c -t i o n f a c t o r . 4 1 0 - . 2 1 0 = 1 . 1 5 z C F . . 3 8 5 - . 2 1 0 Continuing i n the c a l c u l a t i o n of the h e r i t a b i l i t y estimate (h) (from page 3 6 ) , f o r s o l i d s - n o t - f a t - 43 -h = J L x 4 C F . A + B h = 0 . 0 2 3 8 x 4.60 h = 0 . 1 0 9 4 S i m i l a r l y e s t i m a t i n g the h e r i t a b i l i t y f o r b u t t e r f a t h = 0 . 0 4 6 1 x 4 . 6 0 h = 0 . 2 1 2 1 The h e r i t a b i l i t y estimate t h e r e f o r e f o r s o l i d s - n o t - f a t i s 1 0 . 9 $ and f o r b u t t e r f a t 2 1 . 2 $ . Comparison of data from 1 9 5 5 - 1 9 5 6 and 1 9 5 6 - 1 9 5 7 The two sets of data were compared i n s e v e r a l ways. 1 . Seven cows were t e s t e d i n both y e a r s . This provided an o p p o r t u n i t y to compare two g e n e t i c a l l y i d e n t i c a l groups. The d i f f e r e n c e s i n b u t t e r f a t and s o l i d s - n o t - f a t percentages between the two seasons were t e s t e d s t a t i s t i c a l l y . 2 . E x c l u d i n g the seven cows from both y e a r s , the r e s t of the two groups were compared i n the same way. The r e s u l t s are given i n Table XVI. TABLE XVI B u t t e r f a t and s o l i d s - n o t - f a t v a l u e s of groups 1 and 2 , f o r seasons 1 9 5 5 - 1 9 5 6 and 1 9 5 6 - 1 9 5 7 A y r s h i r e s Gr. 1 Fat $ Gr." 2 SWF Gr. 1. $ Gr. 2 1 9 5 5 - 1 9 5 6 1 9 5 6 - 1 9 5 7 D i f f e r e n c e 5 . 1 2 4 . 9 6 0 . 1 6 4 . 6 9 4 . 5 4 0 . 1 5 9 - 6 8 8 . 9 6 ^ 0 . 7 2 9 - 5 0 8 . 9 9 4 0 . 5 1 4 The d i f f e r e n c e s i n the s o l i d s - n o t - f a t percentages were h i g h l y s i g n i f i c a n t (P = 0 . 0 1 ) . The d i f f e r e n c e s i n b u t t e r f a t percentages were not s i g n i f i c a n t . - 44 -The c o r r e l a t i o n c o e f f i c i e n t s f o r b u t t e r f a t and s o l i d s - n o t -f a t f o r d i f f e r e n t years were c a l c u l a t e d . Two c o r r e l a t i o n c o e f f i c i e n t s are shown f o r the year 1955 - 1956. The f i r s t i n c l u d e s a l l cows t e s t e d i n that season; the second i s a r e -s u l t of t e s t s excluding one cow ( C e c e l i a ) , which was extremely low i n f a t and r e l a t i v e l y high i n s o l i d s - n o t - f a t percentage. Two c o r r e l a t i o n c o e f f i c i e n t s are presented f o r 1956 - 1957, one f o r A y r s h i r e s and the other f o r H o l s t e i n s ( f i r s t c a l v e r s o n l y ) . The r e g r e s s i o n equations were c a l c u l a t e d f o r the same groups. These r e s u l t s are given i n Table XVII. TABLE XVII C o r r e l a t i o n c o e f f i c i e n t s and r e g r e s s i o n equations A y r s h i r e s . * 0.389 . *1 = 8.85 • 0.146 X 1955-1956 r - • 0.680 K 2 " Y 2 = 8.12 • 0.286 X A y r s h i r e s 1956-1957 r = + 0.616 Y : : 7.48 • 0.310 X Hoi s t e i n s 1956-1957 r = + 0.570 Y : : 7.12 + 0.454 X The re g r e s s i o n equations are shown g r a p h i c a l l y . i n F i g u r e The e f f e c t of season i s demonstrated i n F igure 7 and the long term trend of b u t t e r f a t i n the U.B.C. herd from I929 - I 9 5 6 i s presented i n F i g u r e 9 . Tables XVIII and XIX show the e f f e c t of age on the l e v e l of s o l i d s ^ n o t - f a t . ± Highly-*, significant-"'E = 0.01 F i g u r e 8 R e l a t i o n s h i p between s o l i d s - n o t - f a t (Y) and milk f a t (X) A y r s h i r e s 1955-1956 Y . 8.12 + 0.286X 3 4 X - PER CENT MILK FAT 5 Figure 9 Fat Percentage of U.B.C. Dairy Herd from 1929-1956. - 48 -TABLE XVIII Cows' age d i s t r i b u t i o n i n 1955-1956 Rang S.N. ;e of F. No. of cows L a c t a t i o n 1st . 2nd 3rd 4th 5th 6 th 7th 8.8 - 9.0 1 1 9.0 - 9.2 1 1 9.2 - 9-4 5 1 1 1 2 9-4 - 9-6 3 1 1 1 9-6 - 9-8 5 4 1 9.8 - 1.0.0 5 2 1 2 TABLE XIX Cows' age d i s t r i b u t i o n i n 1956-1957 Range S . a. F of • Wo. of cows L a c t a t i o n 1st 2nd 3rd 4th 5th 6th 7th 8th 8.3 - 8.5 2 1 1 8.5 - 8.7 1 1 8.7 - 8.9 6 3 1 1 1 8.9 - 9-1 2 2 9.1 - 9.3 3 2 1 9.3 4 3 1 DISCUSSION The r e s u l t s presented here are b e l i e v e d t o be the f i r s t e stimates of h e r i t a b i l i t y of the n o n - f a t t y c o n s t i t u e n t s of milk by the h a l f - s i b c o r r e l a t i o n method. R e s u l t s from workers u s i n g i d e n t i c a l twins show very high h e r i t a b i l i t i e s , of the order of 80 - 90$, f o r these c o n s t i t u e n t s (Hancock 1953). However, i t was mentioned before t h a t these estimates i n c l u d e a l l the - 49 -dominant, e p i s t a t i c , and a d d i t i v e e f f e c t s . The only h e r i t a -b i l i t y estimates d e r i v e d from the daughter-dam c o r r e l a t i o n method (Robertson et_ a l . 1956) give much more c o n s e r v a t i v e f i g u r e s . According to these workers the degree of h e r i t a b i l i t y f o r s o l i d s - n o t - f a t i s around 50$ and f o r b u t t e r f a t i n the neighbourhood of 32$. '. Comparing the r e s u l t s of the i n v e s t i g a t i o n r e p o r t e d here with the estimates mentioned above, there i s a c o n s i d e r a b l e d i f f e r e n c e . The h e r i t a b i l i t i e s of 11.;$ f o r s o l i d s - n o t - f a t and 21$ f ° r b u t t e r f a t are much lower, e s p e c i a l l y f o r s o l i d s - n o t - f a t . The great degree of v a r i a t i o n i n these three Sets of r e s u l t s may be e x p l a i n e d by the f o l l o w i n g o b s e r v a t i o n s . I t should be borne i n mind that h e r i t a b i l i t y estimates f o r a c e r t a i n t r a i t from two d i f f e r e n t p o p u l a t i o n s are not neces-s a r i l y comparable. One has to expect with great p r o b a b i l i t y to get two d i f f e r e n t v a l u e s of h e r i t a b i l i t y f o r two d i f f e r e n t pop-u l a t i o n s . And i t i s not s u r p r i s i n g , that the ranges sometimes are q u i t e wide. The magnitude of the h e r i t a b i l i t y estimate depends mostly on to what degree the worker was able to e l i m i n a t e the e n v i r o n -mental component of v a r i a n c e , and, a l s o , dominance and e p i s t a s i s . The r e l i a b i l i t y of the estimate depends p r i m a r i l y upon the kind and number of animals used and the number of t e s t s made. This i n v e s t i g a t i o n was, of n e c e s s i t y , confined to four small progeny groups i n the U n i v e r s i t y herd. I t seems reasonable to conclude that the much lower value i n the h e r i t a b i l i t y of - 50 s o l i d s - n o t - f a t compared to butterfat could be accounted for by the small number of cows used. On the whole, i t i s not surprising that both values are so low. Robertson used for his calculations t e s t s from Ayrshire cows from 3 3 d i f f e r e n t farms of three counties. It i s quite l i k e l y that those animals closely approximated a random mating population, i n contrast to the U.B.C. herd, which i s p a r t i a l l y inbred with r e l a t i v e l y high average re l a t i o n s h i p . Therefore, the genetic v a r i a b i l i t y i s expected to be lower. The information obtained from t h i s study suggests that fat percentage could be increased i n the U.B.C. herd by selective breeding at a somewhat higher rate than so l i d s - n o t - f a t . Because the average butterfat percentage i n the highly selected and inbred Ayrshire herd i s at the present time 4«8$ and s o l i d s -not-fat 9 . 5 $ , i n contrast to the Ayrshire breed average of 3.81$ and 8 . 9 3 $ , i t i s more l i k e l y that any genetical improve-ment i n these constituents w i l l be very slow. The correlation c o e f f i c i e n t s reported here between fat and solids - n o t - f a t are r e l a t i v e l y very high compared to the res u l t s of other workers, who derived them from large hon-inbred popu-l a t i o n samples. They are + 0.680 for 1 9 5 5 - 1 9 5 6 and + 0.616 for 1 9 5 6 - 1 9 5 7 while Bailey ( 1 9 5 2 a) reports + O . 3 6 6 and & B a r t l e t t and Kay, 1 9 5 0 . B r i t i s h Columbia averages i n use by Canadian R.O.P. indicate Ayrshire butterfat percentage at about the 4»1 l e v e l . - 51 -Robertson (1956) t O.363. B a i l e y s t a t e s (1952 a) t h a t i t i s not a d v i s a b l e to expect i n a random mating p o p u l a t i o n any improve-ment i n s o l i d s - n o t - f a t percentage u s i n g b u t t e r f a t percentage as the only "index f o r s e l e c t i o n . The low c o r r e l a t i o n c o e f f i c i e n t of only about + 0.4 allows f o r a c o n s i d e r a b l e m i n o r i t y of p a i r s of v a l u e s with l i t t l e a s s o c i a t i o n so t h a t i n a herd of cows, i n d i v i d u a l members of i t may be expected to produce milk of above average b u t t e r f a t content and below average s o l i d s - n o t -f a t content and v i c e v e r s a . T h i s reasoning has to be taken with a c e r t a i n degree of r e s e r v a t i o n . I t i s w e l l known that although the b u t t e r f a t l e v e l i s more v a r i a b l e from day to day than the s o l i d s - n o t - f a t , i t i s l e s s s e n s i t i v e to v a r i o u s long term e f f e c t s such as f e e d i n g , d i s e a s e , e t c . , than s o l i d s - n o t - f a t . Therefore i t would be reasonable to expect that the phenotypic c o r r e l a t i o n s can be s t r o n g l y i n f l u e n c e d by the environment. Robertson ( 1 9 5 6 ) , who used g e n e t i c c o r r e l a t i o n s (+ 0.46) and who came to a d i f f e r e n t c o n c l u s i o n , r e a l i z e d t h i s . He b e l i e v e s t h a t the p o s i t i v e genetic c o r r e l a t i o n between f a t and s o l i d s -n o t - f a t means t h a t , i f a t t e n t i o n i s paid to f a t content as w e l l as y i e l d i n breeding, a d e c l i n e i n s o l i d s - n o t - f a t i s almost impos s i b l e . The high phenotypic c o r r e l a t i o n c o e f f i c i e n t (+ 0.680) f o r the U.B.C. herd i n d i c a t e s that s u b s t a n t i a l gain i n s o l i d s - n o t -f a t w i l l occur when s e l e c t i o n i s on the b a s i s of b u t t e r f a t o n l y . The w r i t e r b e l i e v e s t h a t the U.B.C. herd could be used as an example of a long term experiment. During the 28 years of - 52 -e x t e n s i v e s e l e c t i v e b r e e d i n g f o r f a t and y i e l d only, the l e v e l of b u t t e r f a t was r a i s e d remarkably (see Figure 9)« Today the high b u t t e r f a t l e v e l s are a s s o c i a t e d with high l e v e l s of s o l i d s -n o t - f a t . I t can be concluded, that although the most dependable way of improving the s o l i d s - n o t - f a t of milk of i n d i v i d u a l members of a herd i s through the o p e r a t i o n of a breeding p o l i c y to s e l e c t cows d i r e c t l y f o r the high value of the s o l i d s - n o t -f a t content of t h e i r milk, i t i s very d o u b t f u l that i t could be p r a c t i c e d on a l a r g e s c a l e p o l i c y u n t i l there i s a v a i l a b l e a simple method f o r s o l i d s - n o t - f a t d e t e r m i n a t i o n . The l i m i t e d number of cows used f o r t h i s study d i d not permit any r e l i a b l e c o n c l u s i o n i n the matter of the age e f f e c t on the l e v e l of s o l i d s - n o t - f a t , but n e v e r t h e l e s s , there i s one f a c t which can be pointed out, and that i s , the high values of s o l i d s - n o t - f a t f o r f i r s t c a l v e r s . I t i s w e l l demonstrated i n Tables XVIII and XIX. In the season 1955-1956 the number of f i r s t m i l k e r s f a l l i n g i n t o the three top ranges of s o l i d s - n o t -f a t percentages r e p r e s e n t more than 50$ of a l l cows having t h a t p a r t i c u l a r s o l i d s - n o t - f a t content, and none of the h e i f e r s f a l l i n t o the lower groups. On the other hand, most of the o l d cows f a l l i n t o the low ranges. The same r e s u l t emerges from the data of the season 1956-1957' According to these r e s u l t s , the age e f f e c t i n the U.B.C. herd on the f i r s t and second c a l v e r s works i n the same way as found by Drakeley (1927) and B a i l e y (1952 a ) . Some d a i r i e s i n the United S t a t e s pay the farmers f o r milk on both a b u t t e r f a t and s o l i d s - n o t - f a t percentage b a s i s . To - 53 -evaluate' milk f o r t h i s purpose as q u i c k l y as p o s s i b l e , the r e g r e s s i o n equations are used. They are c a l c u l a t e d from the t e s t s of a few hundreds of thousands of samples c o l l e c t e d from the p a r t i c u l a r area. Numerous i n v e s t i g a t i o n s of t h i s k i n d have been p u b l i s h e d . The equations c a l c u l a t e d from the data of t h i s experiment are compared to s e v e r a l others from d i f f e r e n t sources (Table XX). TABLE XX Regression equations from v a r i o u s workers Breed Equation Author Mixed Y - 7.07 + 0.400X M. Jacobson (1936) Y - 7.H + 0.436X L. Jack (1951) Y - 7.67 0.384X 0. Overman (1939) Y = 8.14 + 0.160X A. Provan (1949) A y r s h i r e Y = 6 .77 t O.524X 0. Overman (1939) Y = 8.12 4- 0.286X U.B.C. (1955-1956) Y = 7-48 + 0.310X U.B.C. (1956-1957) H o l s t e i n Y = 6.60 + 0.554X L. Jack (1951) Y = 6 .79 4- 0.613X 0. Overman (1939) Y = 7.12 + 0.454X U.B.C. (1956-1957) I t should be n o t i c e d that a l l these equations vary c o n s i d e r a b l y . There i s no doubt that t h i s method of estimating, s o l i d s - n o t - f a t i s only moderately r e l i a b l e , because s i m i l a r d i f f e r e n c e s un-doubtedly e x i s t w i t h i n an area from farm to farm. The d i s p e r s i o n of i n d i v i d u a l herd s o l i d s - n o t - f a t values about the average f o r any p a r t i c u l a r b u t t e r f a t l e v e l i s such (Provan, Jenkins, 1949) - 54 -t h a t the determination of b u t t e r f a t cannot be a t r u e index of the s o l i d s - n o t - f a t content of the milk from i n d i v i d u a l herds. When t h i s experiment was s t a r t e d i n the season 1955-1956, four cows on the t e s t s had j u s t p r e v i o u s l y c a l v e d . One would expect that the s o l i d s - n o t - f a t l e v e l s i n milk of these cows would d e c l i n e during the 45 days a f t e r c a l v i n g . In c o n t r a s t to t h i s , they r o s e . This f a c t brought to r e a l i z a t i o n t h a t the seasonal e f f e c t which i s shown i n Figure 7 was so str o n g , that i t e l i m i n a t e d the e f f e c t s of l a c t a t i o n and even acted c o n t r a -wise, r a i s i n g the s o l i d s - n o t - f a t l e v e l s . T h i s phenomena can be very h e l p f u l to the farmer to c o n t r o l the l e v e l of s o l i d s - n o t -f a t i n h i s milk by e l i m i n a t i n g the d e t r i m e n t a l environmental f a c t o r s as much as p o s s i b l e . The breeding of the m a j o r i t y of h i s cows f o r a c e r t a i n c a l v i n g season i n the year could r e s u l t i n the r a i s i n g or lowering of s o l i d s - n o t - f a t i n milk, depending on when the c a l v i n g season would f a l l . The l a c t a t i o n a l e f f e c t s should be pronounced i n March, June and November meanwhile during the r e s t of the year i t should be n e g l i g i b l e . The seasonal e f f e c t s shown i n t h i s work are compared to Provan's (1949), which are d e r i v e d from combined samples of l a r g e areas i n F i g u r e 7» To account f o r the s t r o n g l y s i g n i f i c a n t d i f f e r e n c e s i n s o l i d s - n o t - f a t l e v e l s between the two seasons, two main reasons, m a s t i t i s i n f e c t i o n and f e e d i n g , are suggested. Independently to t h i s experiment, l a b o r a t o r y t e s t s of milk samples from a l l cows i n the herd were made i n November I956. - 55 -S e v e r a l c a s e s of s e v e r e m a s t i t i s were d e t e c t e d . R e s u l t s o f t e s t s f o r t h e cows b e i n g u s e d f o r t h i s e x p e r i m e n t a r e r e c o r d e d i n a p p e n d i c e s ' I I H I . S e v e r a l t e s t s were u s e d b u t o n l y t w o , r e s a z u r i h . t e s t and l e u c o c y t e c o u n t a r e l i s t e d . Out o f t h e 28 cows, o n l y 5 were n e g a t i v e i n a l l t e s t s , w h i c h f a c t i n d i c a t e s t h a t t h e i n f e c t i n g b a c t e r i a were s p r e a d t h r o u g h o u t t h e h e r d and t h a t i t i s r e a s o n a b l e t o s u g g e s t t h a t e v e n n e g a t i v e cows m i g h t have b e e n i n f e c t e d p r e v i o u s l y . C o m p a r i n g r e s u l t s of cows w h i c h were, t e s t e d i n b o t h y e a r s f o r s o l i d s - n o t - f a t , a l l o f them showed t r e m e n d o u s d e c l i n e , e v e n V a n i t y , w h i c h was n e g a t i v e i n a l l t e s t s , and A l l i s o n w h i c h was p o s i t i v e o n l y o n c e . V a n i t y was a d i f f e r e n c e of 0 . 4 5 and A l l i s o n 0 . 9 5 i n p e r c e n t a g e o f s o l i d s - n o t - f a t . The l o w e r f i g u r e s were r e c o r d e d i n t h e s e c o n d y e a r . The cow R e n n i e w h i c h showed 1 . 1 7 o f s o l i d s - n o t - f a t d i f f e r e n c e i n p e r c e n t a g e b e t w e e n t h e two s e a s o n s was o n l y p o s i t i v e f i v e t i m e s o u t of t o t a l t e n i n c o n t r a s t t o B e r n i c e w h i c h gave 0 . 7 5 d i f f e r e n c e w i t h n i n e p o s i t i v e t e s t s o u t o f t e n . These e x a m p l e s i n d i c a t e t h a t t h e number o f p o s i t i v e t e s t s i s n o t a d e p e n d a b l e i n d i c a t i o n of t h e e x t e n t t o w h i c h m a s t i t i s i n f e c t i o n a p p a r e n t l y a f f e c t s s o l i d s - n o t - f a t l e v e l s i n m i l k . The m i l k s a m p l e s t e s t e d were c o m p o s i t e s a m p l e s f r o m a l l f o u r q u a r t e r s . T h e r e i s e v i d e n c e f r o m o t h e r w o r k e r s , t h a t e v e n i n d i v i d u a l q u a r t e r s n e g a t i v e t o g e n e r a l l a b o r a t o r y t e s t s c o u l d p o s s e s s s u b c l i n i c a l m a s t i t i s a f f e c t i n g t h e s o l i d s - n o t - f a t l e v e l ( R o w l a n d 1 9 3 7 ' , R o w l a n d and M. Z e i n - E l - D i n e 1 9 3 8 , 1 9 3 9 , Cone 1 9 4 0 , V a n l a u d i n g h a m et_ a l . 1 9 4 0 , C r o s s m a n e t a _ l . 1 9 5 0 ) . - 56 -U n f o r t u n a t e l y , i t i s not p o s s i b l e to assess very p r e c i s e l y the degree of m a s t i t i s i n f e c t i o n nor i t s a f t e r e f f e c t s . The f a c t t h a t the f e e d i n g r a t i o n s of the two seasons p a r t i a l l y d i f f e r e d , i s suggested as a p o s s i b l e minor cause of lowering the s o l i d s - n o t - f a t . Rowland (1946) found t h a t a r a t i o n c o n t a i n i n g 2 5 $ l e s s energy than normal, reduced the s o l i d s - n o t - f a t content of the milk from 8.7$ to 8.3$, whereas one with 40$ l e s s p r o t e i n e q u i v a l e n t than normal reduced i t to only 8.5$« A s i m i l a r kind of experiment was conducted i n New Zealand (Riddet et a l . 1941) where a h a l f - p r o d u c t i o n r a t i o n caused s o l i d s - n o t - f a t ' t o drop 0.3 - 0.5 i n percentage. By r e v e r s i n g the r a t i o n to normal, the percentage of s o l i d s -n o t - f a t i n c r e a s e d to the normal l e v e l . The f a t percentage d i d not respond s i g n i f i c a n t l y . Based on these p u b l i c a t i o n s , the f i r s t assumption was, that the r a t i o n of the U.B.C. herd d i d not represent any below normal standard and that the l e v e l of s o l i d s - n o t - f a t should not have dropped because of i t . But Holmes e_t a l . (1956) presents an i n t e r e s t i n g experiment where he shows th a t even small d i f f e r e n c e s of g r a i n r a t i o n r e s u l t i n g i n d i f f e r e n c e s i n energy i n t a k e , may vary the s o l i d s - n o t - f a t l e v e l s . Having three groups of cows X,Y,Z and f e e d i n g them g r a i n at r a t e s of 1 l b . to 2.7, 2.3 and 2.1 l b s . milk r e -s p e c t i v e l y , he showed that the Y r a t i o n r a i s e d the s o l i d s - n o t -f a t from the X l e v e l of 8.62$ to 8.75$. The Z r a t i o n , however, produced no f u r t h e r i n c r e a s e i n s o l i d s - n o t - f a t . The g r a i n r a t i o n s of t h i s experiment were about 1 l b . of g r a i n to 2 l b s . - 57 -m i l k i n 1955 - 1956 and about 1 to 3 i n 1956 - 1957 and t h i s may have c o n t r i b u t e d to the observed change i n s o l i d s - n o t - f a t l e v e l . One cannot be very p o s i t i v e on t h i s p o i n t , however, because feeds other than g r a i n a l s o d i f f e r e d between the two seasons. This problem s t i l l r e q u i r e s a great d e a l of f u r t h e r i n v e s t i g a t i o n . Continued s t u d i e s of the U n i v e r s i t y herd might p r o v i d e data which would i n d i c a t e whethere the decrease i n s o l i d s - n o t -f a t was due to m a s t i t i s or d i f f e r e n c e s i n f e e d i n g . B a i l e y (1952 a) s t a t e s that the c o e f f i c i e n t of v a r i a t i o n f o r b u t t e r f a t i s 10$ and f o r s o l i d s - n o t - f a t only 3$. I t i s i n t e r e s t i n g to note t h a t the c o e f f i c i e n t of v a r i a t i o n f o r s o l i d s - n o t - f a t i n t h i s work f o r 1955 - 1956 i s n e a r l y the same (2.98$) and f o r b u t t e r f a t r e l a t i v e l y lower (7*36$). But the most i n t e r e s t i n g phenomena i s that the f o l l o w i n g year 1956 - 1957, s i m u l t a n e o u s l y with the decreasing s o l i d s - n o t - f a t the c o e f f i c i e n t of v a r i a t i o n dropped down to 1.85$ while f o r b u t t e r f a t i t dropped to 6.77$. Because B a i l e y a l s o p r e s e n t s some data showing changes of cor -r e l a t i o n c o e f f i c i e n t s due to m a s t i t i s , i t i s l i k e l y t h a t the decrease i n the c o e f f i c i e n t of v a r i a t i o n observed here was due to m a s t i t i s . I t should be mentioned a l s o t h a t there i s no evidence i n the l i t e r a t u r e to i n d i c a t e that the small change i n f e e d i n g p r a c t i c e could i n f l u e n c e so s t r o n g l y the c o e f f i c i e n t of v a r i a t i o n . I t would seem reasonable to conclude that the low l e v e l of s o l i d s - n o t - f a t i n 1956 - 1957 was caused p r i m a r i l y by m a s t i t i s i n f e c t i o n with d i f f e r e n c e s i n f e e d i n g p r a c t i c e a - 58 -p o s s i b l e c o n t r i b u t a r y cause. F i g u r e 8 shows th a t the whole herd was a f f e c t e d evenly. Had t h i s not been the case, the slope of the r e g r e s s i o n equation l i n e f o r the year 1956 - 1957, would have changed. However, the r e g r e s s i o n equation l i n e s are p a r a l l e l . The r e s u l t s f o r H o l s t e i n s are presented only f o r the purpose of comparison with the A y r s h i r e s . The average v a l u e s f o r b u t t e r f a t (3.57$) and s o l i d s - n o t - f a t (8.74$) obtained i n t h i s i n v e s t i g a t i o n are s l i g h t l y above the average values f o r H o l s t e i n breed (3*45$ f a t and 8.60$ s o l i d s - n o t - f a t . ) Two cows out of the ten t e s t e d gave t e s t s 8.25$ f o r s o l i d s . - n o t - f a t . Because a l l of the H o l s t e i n s are f i r s t c a l v e r s and because the values f o r f a t and s o l i d s - n o t - f a t vary between cows to a great degree, no c o n c l u s i o n s can be made. I t i s b e l i e v e d t h a t t h i s paper pre s e n t s enough evidence to support the f o l l o w i n g s u g g e s t i o n s . From the breeding aspect, i t does not seem necessary to adopt t e s t i n g f o r s o l i d s - n o t - f a t on a l a r g e scale because s e l e c t i o n f o r b u t t e r f a t can be expected to e i t h e r maintain or s l i g h t l y i n c r e a s e s o l i d s - n o t - f a t l e v e l s . From a n u t r i t i o n a l viewpoint, however, i t i s d e s i r a b l e to i n -crease the s o l i d s - n o t - f a t content of milk as much as p o s s i b l e , and to do t h i s , t e s t i n g f o r s o l i d s - n o t - f a t would be d e s i r a b l e . Somewhat f a s t e r progress i n improving s o l i d s - n o t - f a t l e v e l s would be expected i f t e s t s f o r both b u t t e r f a t and s o l i d s - n o t - f a t were made, r a t h e r than f o r b u t t e r f a t only. I t would appear t h a t m a s t i t i s , because of i t s wide d i s t r i b u t i o n , presents a s e r i o u s & B a r t l e t t and Kay, 1950. - 59 -o b s t a c l e t o the a c c u r a c y of s e l e c t i o n p r a c t i c e . D i f f e r e n c e s i n f e e d i n g , e s p e c i a l l y i n r e s p e c t t o the energy content of r a t i o n s , c o n s t i t u t e a f a c t o r a l s o r e q u i r i n g a t t e n t i o n . - 60 -SUMMARY 1. During the p e r i o d of f o u r months i n 1955 - 1956 the milk of twenty A y r s h i r e cows was sampled and t e s t e d f o r b u t t e r -f a t and s o l i d s - n o t - f a t . In the same p e r i o d of 1956 - 1957 eighteen A y r s h i r e s and ten H o l s t e i n s were s i m i l a r l y t e s t e d . 2. Great d i f f e r e n c e s i n the values of s o l i d s - n o t - f a t of A y r s h i r e cows between the two seasons were observed and recorded; Seven cows t e s t e d i n both seasons showed a d i f f e r e n c e of 0.72 i n percentage of s o l i d s - n o t - f a t . The r e s t of the t e s t e d cows gave a'.difference of 0.51 i n percentage of s o l i d s - n o t - f a t . Both d i f f e r e n c e s were h i g h l y s i g n i f i c a n t . Wo s i g n i f i c a n t d i f f e r e n c e was found between the b u t t e r f a t v a l u e s . 3. On the b a s i s of these t e s t s the h e r i t a b i l i t y estimates f o r s o l i d s - n o t - f a t ('IJjiS) and b u t t e r f a t (."21$) were determined. 4. The c o r r e l a t i o n c o e f f i c i e n t s f o r f a t and s o l i d s - n o t - f a t of A y r s h i r e s f o r the two seasons were + 0.680 and *• 0.618 r e s p e c t i v e l y . The value f o r H o l s t e i n s , 1956 - 1957 season only, was + 0.570. 5. R e g r e s s i o n equations are presented for 1955 - 1956, Y - 8.12 + 0.286X1 and f o r 1956 - 1957, Y = 7.48 + 0.310X, and f o r H o l s t e i n s Y = 7.12 + 0.454X. These equations are d e r i v e d from the data of t h i s i n v e s t i g a t i o n and p r o v i d e a b a s i s f o r e s t i m a t i n g s o l i d s - n o t - f a t values (Y) from b u t t e r f a t values (X). - 61 -The e f f e c t s of age and season on s o l i d s - n o t - f a t l e v e l s are demonstrated and d i s c u s s e d . The d i f f e r e n c e between the c o e f f i c i e n t s of v a r i a n c e f o r s o l i d s - n o t - f a t f o r the two seasons as i n d i c a t i v e of m a s t i t i s i n f e c t i o n i s d i s c u s s e d . The importance of feed on the l e v e l of s o l i d s - n o t - f a t i s i n d i c a t e d . The q u e s t i o n of t e s t i n g milk f o r s o l i d s - n o t - f a t with r e s p e c t t o a c h i e v i n g g e n e t i c a l improvement i s expl o r e d . I t i s suggested t h a t the p r e d i c t i o n of s o l i d s - n o t - f a t v a l u e s from b u t t e r f a t t e s t s i s not a very r e l i a b l e method of determining s o l i d s - n o t - f a t l e v e l s of i n d i v i d u a l herds. APPENDIX I R e s u l t s of milk t e s t s 1955-1956 A y r s h i r e s No. Name ON o vO H CM o a a a <D cd cd cd a >s >-} vO O -4 CV o rH CD -» ON H HO X ! X ! X ! cd • • ' • • O o o > £> U fn CD CD CD cd cd cd > • fr, fu o A l l i s o n T.S. 14.8 15.1 15.5 15.6 16.3 15.0 15-4 15.6 13.9 15.5 15.27 SNF*4 9.7 10.0 9.8 10.2 10.1 10.3 9.6 9.9 9.0 9.8 9.84 3.75 F 5.1 5.1 5.7 5.4 6.2 4-7 5.8 5.7 4.9 5.7 5.43 8.21 2 Amber T.S. 15.8 15 .8 15.8 15.6 16.0 15 .8 15 .6 15 • 5 15.5 15.3 15.67 SNF 9.4 10 .1 10.5 10.1 10. b 10.3 9.3 9 .6 9-7 9.8 9.88 3 .96 F 6.4 5 .7 5.3 5.5 6.0 5.5 6.3 5 • 9 5.8 5.5 5.79 6 .67 3 A n i t a T.S. 13.4 13 .8 14.4 14.2 15.1 14.0 14.0 14 .5 14.6 14.7 14.27 SNF 8.9 9 .5 9.0 9-4 8.9 9.8 9-1 9 .2 9.3 9.3 9.24 3 .05 F 4.5 4 .3 5.4 4.8 6.2 4.2 4.9 5 .3 5.3 5.4 5.03 11 .29 4 Barones s T.S. . 14.8 15 .0 15.2 15.0 15.8 15.1 15.0 14 .8 14.8 14.6 15.01 SNF 9.5 9 .5 9.5 9.6 9.7 9.8 9.2 9 .3 9.4 9.4 9.49 1 .89 F 5.3 5 • 5 5.7 5.4 6.1 5.3 5.8 5 .5 5.4 5.2 5.52 5 .25 A T.S. = t o t a l s o l i d s AA SNF = solids-ncTt-f at AAA - c o e f f i c i e n t of variance APPENDIX I R e s u l t s of milk t e s t s 1955-1956 A y r s h i r e s Wo. Name ON O o -* CN2 o H CO rH sO H CV ON rH C\! X ! X ! X ! to cti . • • • • • . o o O O a d X> X> fn fn fH CO 0 (tS CO CO CO cd > a •"3 •-a •"3 Ft, ' fx, o Bernice T.S. 1 5 . 1 1 5 . 2 1 5 . 8 15-7 16 .2 15-4 16 . 0 15-9 15-7 15-6 1 5 . 6 6 SNF 9 . 9 1 0 . 0 1 0 . 3 9-9 1 0 . 2 9 . 9 9-7 1 0 . 2 9 . 7 9-7 9-95 2 . 4 4 F 5 . 2 5 . 2 5 .5 5 . 8 6 . 0 5.5 6.3 5 . 7 6 . 0 5 . 9 5 .71 6 . 10 B e t t y T.S. 14.5 1 4 . 4 14-5 14-7 1 4 . 5 1 4 . 6 14.6 1 4 . 8 14.6 1 4 . 6 14-58 SNF 9 . 9 9 . 9 9 . 4 9 . 9 9 . 5 9 . 9 9-4 9 . 7 9 . 6 9 . 7 9 . 6 9 2.13 F 4 . 6 4 . 5 . 5 . 1 4 . 8 5 . 0 4 . 7 5 . 2 5 . 1 5 . 0 4 . 9 4 . 8 9 4 . 7 3 Brenda T.S. 1 4 . 1 14-1 1 4 . 6 1 4 . 3 1 5 . 0 1 4 . 1 1 4 . 2 14-2 1 3 . 7 1 3 . 8 1 4 . 2 0 SWF 9 .3 1 0 . 0 1 1 . 0 9 . 8 9-9 9-9 9 . 3 9-6 9 . 4 9 . 2 9 . 7 4 5 .76 F 4 . 8 4 . 1 3-6 4 . 4 5 . 1 4 . 2 4-9 4 . 6 4 . 3 4 . 6 4 . 4 6 9-50 Brownie T.S. 1 3 . 5 13-6 13-7 1 3 . 6 1 4 . 0 1 3 . 4 13-4 13 .2 1 3 . 2 1 3 . 1 1 3 . 4 7 SNF 9 . 5 9 . 3 - 9 . 5 9 . 7 9-6 9-7 9-1 9 . 2 9-2 9 . 2 9 . 4 0 2 . 4 4 F 4 . 0 4 .3 4 . 2 3 . 9 4 . 4 3 . 7 4 . 3 4 - 0 4 . 0 3 . 9 4 . 0 7 5-66 APPENDIX I R e s u l t s of milk t e s t s 1955-1956 A y r s h i r e s vO ON o o CM Oi o H age H vO H ON H X! X! age • o CO Q Jan. Jan. Jan. Feb. Feb. Feb. Marc Marc Marc Aver No. Name 9 Cathy T.S. 14-5 14.8 15.0 15.4 16.1 14.7 14-9 14.6 14-9 15-0 14.99 SNF 9-8 9-6 9-4 9.8 9.8 10.0 9-5 9-4 9.5 9.8 9-66 2.13 F 4.7 5.2 5.6 5.6 6.3 4-7 5.4 5.2 5.4 5.2 5-33 8.90 10 C e c e l i a T.S. 12.5 13.0 13.3 12.8 12.9 13.0 12.7 12.4 12.6 12.7 12.79 SNF 9.2 9-9 10.5 9*8 10.1 10.2 9-5 9.6 9.6 10.0 9.84 3.80 F 3.3 3.1 2.8 3.0 2.8 2.8 3.2 2.8 3.0 2.7 2.95 7«48 11 Crocus T.S. 14.3 14.1 14.5 14-6 15.1 14.8 14.6 14.6 14.1 14.2 14.52 SNF 9.3 9-6 9-9 9-8 9.8 9.8 9-3 9.8 9-5 9.3 9.61 2.30 F 5.0 4.5 4.6 4.8 5.3 5-0 5.3 4.8 4.6 4-9 4.91 5.31 12 C r y s t a l T.S. SNF F 14.0 14.1 14.2 14.1 14.4 13.6 13.7 14.1 13.7 13.6 13.95 9.5 9-8 9*9 9-8 9-7 9.8 9.3 9-9 9.4 9.6 9-67 2.21 4.5 4.3 4.3 4.3 4.7 3.8 4.4 4.2 4.3 4.0 4.28 6.20 APPENDIX I R e s u l t s of m i l k t e s t s 1 9 5 5 - 1 9 5 6 A y r s h i r e s N O ON N O • • o C C cu crj crj Q >s ••-3 O o -4 CM O N rH CM ON H x: X! X! • • • • O O O C Xi Xi Xi U fn cd CD <D <D cd cd cd »"3 S CD W> cd C D > «aj O No. Name 13 Omega T.S. 1 3 - 0 1 3 . 8 1 4 . 9 1 4 . 3 1 4 . 3 ' 1 4 . 4 1 4 - 3 1 3 - 6 1 4 - 3 1 3 - 8 1 4 . 0 7 SNF 9 . 4 9 - 3 9 . 9 9 . 4 9 - 4 9 - 6 9 . 2 9 - 1 9 . 4 9 . 2 9 - 3 9 2 . 4 8 F 3 . 6 4 . 5 5 . 0 4 . 9 4 . 9 4 . 8 5 . 1 4 . 5 4 . 9 4 . 6 4 . 6 8 9 . 3 9 14 P a t r i c i a T.S. 1 3 . 3 13*3 1 3 . 7 1 3 . 4 SNF 8 . 5 9 * 4 9 . 0 9 . 3 F 4 . 8 3 . 9 4 - 7 4 . 1 1 4 . 9 1 3 . 4 1 3 . 3 1 3 . 7 1 3 . 2 1 2 . 8 1 3 . 5 0 1 0 . 5 9 - 4 9 - 0 9 - 0 9 - 0 9 - 0 9 . 2 1 5 . 7 9 4 . 4 4 . 0 4 . 3 4 . 7 4 . 2 3 . 8 4 . 2 9 9 . 2 9 15 Peggy T.S. 1 4 . 5 1 4 . 7 1 4 . 4 1 5 - 5 1 5 . 7 1 5 . 2 1 5 . 3 1 5 . 3 1 5 . 1 1 5 . 1 1 5 . 1 0 SNF 9 . 5 9 . 8 9 . 5 9 . 6 9 . 9 9 . 7 9 - 4 9 - 0 9 . 3 9 . 4 9 . 5 1 2 . 7 6 F 5 - 0 4 - 9 4 - 9 5 . 9 5 . 8 5 . 5 5 . 9 6 . 3 5 . 8 5 . 7 5 . 5 7 8 . 4 5 16 Rennie T.S. SNF F 1 3 . 8 1 3 . 7 1 3 . 7 1 3 . 7 1 4 . 1 1 3 . 4 1 3 . 7 1 3 . 6 1 3 . 7 1 3 . 9 1 3 . 7 3 9 . 5 9 . 6 9 . 2 9 . 5 9 - 4 9 . 2 9 . 3 9 . 6 9 . 7 1 0 . 0 9 . 5 0 2 . 4 5 4 . 3 4 . 1 4 . 5 4 . 2 4 - 7 4 . 2 4 . 4 4 . 0 4 . 0 3 - 9 4 . 2 3 6 . 3 6 APPENDIX I R e s u l t s of. milk t e s t s 1955-1956 A y r s h i r e s N O O N O o ~* Oi o r-i (D N O CM O N r-i XI XI X! OO cd • • • • • • • * o o O U > O a 0 xt X> X> u SH CO cd CT) cd CO CO CO ct) cd cd > • Q •-3 CM a <3j o No. Name 17 R i t a T.S. 16.5 14-1 13.2 13-4 13-6 13.6 13.2 13.1 13-0 13.O 13-67 SNF 9.0 9.3 9-0 8.9 9-0 8.9 8-7 9-0 9-0 8.9 8-97 1-66 F 7-5 4.8 4.2 4-5 4.6 4.7 4.5 4.1 4-0 4-1 4-70 7-15 18 S h e i l a T.S. 12.7-13.5 13.5 13.4 13-9 13.0 12.9 12.9 12.9 12'. 9 13-16 SNF 8.8 9-4 9.3 9.1 9-6 9-3 9-1 8.6 8.9 8.7 9.08 3.73 F 3.9 4.1 4.2 4.3 4.3 3-7 3.8 4-3 4.0 4.2 4.08 5-26 19 Temptress T.S. 13-1 13-4 13-3 13-7 14.5 13-3 13.6 13-7 12.8 13-7 13-51 SNF 9.3 9-7 9-1 9.3 9-2 9-4 9-3 9-1 8.8 9-3 9.25 2.49 F 3-8 3-7 4.2 4.4 5.3 3.9 4.3 4.6 4-0 4.4 4.26 10.61 20 V a n i t y T.S. 15.5 16-5 16-3 16.6 17-1 16.0 16.4 16.2 16.2 16.1 16.29 SNF 9.9 10.3 9.9 10.2 10.4 10.2 9.7 9.8 9.8 9-8 10.00 2.53 F 5.6 6.2 6-4 6-4 6.7 5.8 6.7 6.4 6.4 6.3 6.29 5.55 Average c o e f f i c i e n t of varia n c e f o r s o l i d s - n o t - f a t i s 2.98. Average c o e f f i c i e n t of varia n c e f o r b u t t e r f a t i s 7-36. APPENDIX I I R e s u l t s of milk t e s t s 1956-1957 A y r s h i r e s Name . A l l i s o n A n i t a Bernice CM to UN H CN CM o CM ON • > o Nov. Nov. Nov. Nov. • o CD Dec . T.S. 14• 5 13.7 13. 9 SNF -8. 9 8.9 8. 9 F 5-6 4.8 5-i 2 0 Leucocyte s — Resazurin + 14.0 8.7 5-3 13-7 9.1 4.6 13-9 8.9 5.0 T.S. 12.3 SNF 8.8 F 3-5 13-7 8.8 4-9 14 .2 8.8 5-4 14-2 8.6 5.6 13 .2 8.7 4.5 15.0 8.5 6.5 Leucocytes — + i R e s a z u r i n + + + 13.5 9.0 4.5 14.8 8.6 6.2 0 O CD CM ON H M cd • . U O G . G Q) CD cd cd > Q •-3 >-3 13.5 8.8 4.7 14-3 8.9 5.4 13 -7 8.9 4.8 14.5 8.8 5-7 o 13.6 13.80 8.8 8.89 1.23 4.8 4.91 6.74 14.6 14.08 8.8 8.73 1-39 5.8 5-35 16.22 T.S. 14.9 SNF 9-3 F 5.6 Leucocytes 14.90 9.20 1.24 5.70 4-21 R e s u l t s of APPENDIX II milk t e s t s 1956 A y r s h i r e s - 1 9 5 7 UN CM ON 0 0 0) Cxi to H CM CM v O r H CM ON aO • • • • • • • . • • u 0 > > > > > o O O C CO o o o o o 0) 0) 0) cd cd Q Q Q < > No. Name 4 Crocus T.S. 1 2 . 8 13 .8 1 4 . 0 1 3 . 2 1 3 . 7 1 3 . 6 1 3 - 6 13 . 2 13 -2 1 3 . 4 1 3 . 4 5 SNF 9 . 2 9 - 1 9 . 0 9 - 2 9 - 1 8 - 9 9 - 1 8.8 8 . 7 8 . 9 9 . 0 0 1 . 3 9 F 3 - 6 4 - 7 5 . 0 4 . 0 4 . 6 4 . 7 4 . 5 4 . 4 4 . 5 4 . 5 4 . 4 5 8.81 Leucocytes - - •»• + Re s a z u r i n + «• 5 C r y s t a l T.S. 1 4 . 5 13 . 2 1 3 . 5 1 3 - 2 13- 4 1 4 . 3 1 3 - 9 1 3 . 7 1 3 . 6 1 3 . 8 1 3 . 7 1 SNF 9 - 0 8 . 9 9 - 1 8 . 9 8. 8 9 - 1 9 - 0 8 . 9 8 . 9 9 . 0 8 . 9 6 9 . 1 2 F 5 . 5 4 - 3 4 . 4 4 . 3 4 . 6 5 . 2 . 4 . 9 4.8 4 . 7 4 . 8 4 . 7 5 8 . 1 4 Leucocyt es - + -Re s a z u r i n — — — 6 Cherry T.S. 1 3 . 6 1 4 . 0 1 5 . 0 1 4 - 0 1 3 - 6 1 4 . 2 1 3 . 4 1 3 . 6 1 3 . 9 13 .8 1 3 . 9 2 SNF 9 - 7 9 - 7 9 . 2 9 . 6 . 9 - 5 9 - 5 9 - 4 9 . 4 9 . 5 9 . 5 9 . 5 1 2 . 3 1 F 3 . 9 4 - 3 5.8 4 • 4 4 . 1 4 . 7 4 . 0 4 . 2 4 . 4 4 . 3 4 . 4 1 1 2 . 1 9 Leucocyt e s - i 2 + Re s a z u r i n R e s u l t s of APPENDIX II milk t e s t s 1 9 5 6 Ayr s h i r e s - 1 9 5 7 UN CN ON o o CD to H vO ON rH bO • • • • . • • » . u 0 > > > > > o O c CD o o o o o CD CD CD crj crj > • S3 S3 s O Q n •-3 > No. Name 7 Diana T.S. 14.2 13.5 14.7 1 4 . 0 14-3 14.5 13-5 1 4 . 2 14- 2 1 4-5 1 4 . 2 1 SNF 9.6 9-5 9.5 9.3 9-2 9-4 9-1 9.3 9-2 9.4 9 . 4 0 1.47 F 4.6 4 . 0 5.2 4.7 5.1 5-1 4.4 4.9 5 . 0 5.1 4.81 7.98 Leucocyt e s - - + - -R e s a z u r i n + + — 8 Daisy T.S. 1 4 . 8 1 5 . 1 1 5 . 6 15-9 1 5 . 1 1 6 . 0 15.2 1 4 . 8 1 4 . 8 15 . 0 1 5 . 1 3 SNF 9.3 9-1 8.9 9-5 9-8 9-7 9-4 9-5 9.4 9.3 9 . 2 9 2.81 F 5.5 6 . 0 6.7 6.4 5.3 6.3 5.8 5.3 5.4 5.7 5.84 8.48 Leucocyte s 4- + + - -Re s a z u r i n + + *• — 9 Daphne T.S. 1 4 . 4 1 4 . 0 1 4 . 1 1 4.6 1 5 . 1 1 4 . 5 1 4.6 1 4 . 4 . 1 3 . 9 14-3 1 4 . 3 9 SNF 8.9 .8.8 8.8 8.7 8.8 9 - 0 8.9 8 .9 8,.-9 9 . 0 8.87 1.57 F 5.5 5.2 5.3 5.9 6.3 5-5 5*7 5.: 5 5 . 0 5.3 5.52 6.76 Leucocyt es - I 2 - - -Re s a z u r i n - _ _ + APPENDIX II R e s u l t s of milk t e s t s 1956-1957 A y r s h i r e s CM o ON o O CO to H OJ OJ vO CM ON H OO ce • • • • • • • • • • o > > > > > o o o G Cl CO O o o o o CO CO CO cd ca > • Q Q •"3 »"3 > No. Name T.S. 13.0 13.4 12.9 13.3 13.9 13.0 13. 6 13.8 12 .6 13.1 13.19 SNF 8.7 9.0 8.9 8.9 8.8 8.9 8. 8 8.9 8 • 9 9.0 8.81 1.22 F 4-3 4.4 4.0 4.4 5-1 4.1 4. 8 4-9 3 .7 4.1 4.38 10.02 Leucocyte s + - • . + -Re s a z u r i n + - - - -11. D e l i a T.S. 13.1 12.8 12.9 12 .6 12.8 12.8 12. 9 12.4 12.7 12. 9 12.73 SNF 9.3 9.1 9.1 8 .8 8.8 8.8 8.7 8.7 8.7 8. 8 8.82 2.35 F 3.8 3.7 3-8 , 3 .8 4.0 4.0 4.2 3-7 4.0 4. 1 3.91 4.42 Leucocyte s - - -R e s a z u r i n 4- t -12 Doranne T.S. 13.l 13.3 13-9 13-7 14-1 SNF 9.0 9-0 9.2 9.0 9.2 F 4-1 4-3 4.7 4-7 4.9 Leucocytes Resazurin • - - + 14.0 14.4 14.3 14-1 14.2 .13.91 9.2 9-3 9.2 9.1 9.1 9.13 2.03 4.8 5.1 5.1 5.0 5.1 4-78 7.17 APPENDIX I I R e s u l t s o f milk t e s t s 1956-1957 A y r s h i r e s U N CM o C N o O CD CM to r H CM CM CM ON H bO cd • • • • • • • • • • • ^ > > > o o fl C CD o o O O O CD co CD crj crj > • 525 52! S3 S3 Q Q •"3 > No. Name 13 Dorothy T.S. 13.8 13.1 13-6 13.5 13-5 13.6 13.3 13.5 13-7 13-7 13-55 "SNF 9.5 9.3 9.2 9.6 9-5 9-4 9.2 9.3 9-5 9-5 9.42 1.59 F 4.3 3.8 4.4 3.9 4.0 4.2 4.1 4.2 4.2 • 4.2 4.13 4.45 Leucocytes g - - + Resazurin -14 Penelope T.S. 13.6 12.7 13.1 12.6 12.6 13-3 12.6 13.3 12.6 13.1 12.95 SNF 8.8 8.3 8.5 8.2 8.5 8.8 8.6 8.5 8.6 8.6 8.54 2.25 F 4.8 4.4 4.6 4.4 4.1 4.5 4.0 4.8 4.0 4.5 4.41 6.71 Leucocytes • -Resazurin + + - + + 15 Rennie T.S. 12.5 12.2 12.5 12.1 12.1 12.4 12.7 12.0 12.6 12.4 12.35 SNF 8.4 8.4 8.4 7.9 8.3 8.5 8.4 8.1 8.5 8.4 8.33 2.24 F 4.1 3.8 4.1 4.2 3-8 3.9 4.3 3.9 4.1 4.0 4-02 4.23 Leucocytes • Resazurin + • + * APPENDIX I I R e s u l t s of milk t e s t s 1956-1957 A y r s h i r e s CM to H CM CM ON CM vO ON rH 0 CM • ON 0 H Average • !> o • > o • o • > o • !> o . O CO Q O CO Q • O CO a • PI ct) •"3 • >-i n3 Average 0 • > No. Name 16 • Thelma T.S. 12.4 12.0 12.1 12. 5 11.5 12.9 12.0 12.2 12.5 12.4 12.25 SNF 8.4 8.0 8.3 8.4 8.0 8.5 8.5 8.4 8.5 8.5 8.35 2.36 F 4.0 4.0 3-8 4.1 3-5 4-4 3.5 3.8 4.0 3.9 3.90 6.36 Leucocytes 4 + + • Re s a z u r i n + 4- 4- 4-17 T i s h T.S. 13-3 13.1 12.5 13.1 12.3 13.5 12.6 12.6 12.6 12.7 12.65 SWF 9.2 9.0 9-0 9-1 8.7 8.9 9.0 8.8 9.0 8.9 8.78 1.65 F 4.1 4.1 3-5 4.0 3.6 4-6 3.6 3-8 3.6 3.8 3.87 8.68 Leucocytes • - - - -Re s a z u r i n — — 18 V a n i t y T.S. 14-9 14.6 15.2 15.8 15-3 15.6 14.9 15 .1 15.1 15.3 15.12 SNF 9.3 9.4 9-8 9-7 9-7 9.7 9-3 9-9 9.6 9.7 9.55 1.84 F 5.6 5.2 5.4 6.1 5.6 5.9 5.6 5.2 5.5 5.6 5.57 4.66 Leucocytes - - - - -Re s a z u r i n — — — -* •— Average c o e f f i c i e n t of v a r i a n c e f o r s o l i d s - n o t - f a t i s 1.85 Average c o e f f i c i e n t of v a r i a n c e f o r b u t t e r f a t i s 6.77 APPENDIX I I I R e s u l t s of milk t e s t s 1956-1957 H o l s t e i n s No. Name CM > o Beauty Vale T.S. 13.7 SNF 9.1 F 4.6 Leucocyte s Resazurin UN CM CN o o GO to i—l CM o NO r-f CM CN bO CM cd • • • • . . . * • in O > !> > > o O O C CD o o o O CP 0) CD cd cd • Q Q n •-a •"3 < > 12. 8 12. 2 12 .5 11. 7 12.4 12. 0 12.3 11.7 11. 8 12.32 8. 6 8.5 8 .7 8. 5 8.6 8. 5 8.4 8.5 8. 5 8.59 2. 2< 4. 2 3.7 3 .8 3-2 3.8 3- 5 3-9 3.2 3. 3 3.73 12. 0< Diamond T.S. 12.4 12.4 12.2 12.3 12.7 12. 3 12 .5 12. 5 12 .6 12.5 12.45 SNF. 8.9 9.0 9.1 9.0 9-0 9.0 9 .1 8. 9 9 .0 , 8.9 8.99 2. 60 F 3.4 3-5 3.2 3.3 3.7 3.3 3 .4 3. 6 3 .6 3.6 3-46 4. 83 Leucocyte s + 1 2 4. + + Re s a z u r i n + - * -3 Judy T.S. 13.1 13 .2 13.1 12.7 13.. 13.5 13- 5 13 .2 13.4 13.4 13.23 SNF 9.7 8.9 9-1 8.8 8.9 9.1 . .9-0 8.9 9.1 9.2 9.06 2.91 F 3.4 4.3 4.0 3.f 4.4 4.4 • 4. 5 4.3 4.3 4.2 4.17 7.79 Leucocyte s - - - -Re s a z u r i n 4- 4. + APPENDIX I I I R e s u l t s of milk t e s t s 1956-1957 Hoist eins UN 0 S <r\ O o 0 CM to rH CN OJ vO rH CJ H 00 CO • • • • • • • • • • • SH > > > > > o o o fl C 0 o o O O o CO CO 0 cO cO > • Q Q Q •"3 "-3 > No. Name 4 L i l y T.S. 11 .9 11.5 11.9 11 .6 11.5 11 . 9 H - 7 11 . 9 H « 9 11 . 7 11.75 SNF 8.9 8.2 8.1 8.1 8.0 8.2 8.2 8.3 8.3 8.2 8.25 2.98 F 3.0 3-3 3.8 3.5 3-5 3.7 3.5. 3.6 3-6 3-5 3.50 6.31 Leucocytes -Resazurin - - - - -Mi l d r e d T.S. 12.8 12.3 12.2 12.2 12.3 12-7 12.5 12.3 12.2 12.4 12.41 SNF 9.1 8.8 8.6 8.6 8.5 8.6 8.5 8.7 8.6 8.7 8.67 2.05 F 3.7 3.5 3.6 3.6 3-8 4.1 4-0 3.8 3-6 3.7 3-74 5.05 Leucocytes - - - -Resazurin - - - -Miranda T.S-. 12.3 11.9 12.1 12.1 12.0 12.0 12.1 12.1 12.0 12.0 12.06 SNF 8.9 8.6 8.7 8.8 8.7 8.7 8.7 8.8 8.8 8.8 8.75 1.02 F 3.4 3.3 3-4 3-3 3-3 3.3 3-4 3.3 3-2 3.2 3-31 2.-24 Leucocytes - - - -Resazurin + - + APPENDIX I I I R e s u l t s of milk t e s t s 1956-1957 Hoi s t e i n s co UN rH CM CM 0 CM ON rH 0 CM ON O H Average • > o • s> o 25 > O • !> O 3 > O . O CD a • O CD Q • O CD a • C crj •~3 crj Average 0 > No. Name 7 Paula T.S. 12.6 12. 5 12.0 12.4 12 .4 12 .5 12.4 12.1 ,12.1 12.0 12.30 SNF 9.3 9.0 8.9 8.9 8.8 8.9 8.7 8.9 " 8.9 8.9 8.92 1 .77 F 3-3 3.5 3.1 3-5 3.6 3.6 3.7 3.2 3-2 3.1 3.3.8. 6 .65 Leucocyte s - - + - + Re s a z u r i n — — + 8 R.A. B e l l e T.S. 13.3 13-3 14.0 13.3 13.0 13.2 13 .2 13.2 13.4 13 .2 I 3.3I SNF 9:1 9.0 9-1 9-1 9.2 9.1 9.2 9.2 9.1 9-1 9.12 0 .73 F 4.2 4.3 4.9 4. 2 3.8 4-1 4.0 4.0 4.3 4.1 4.19 6 • 94 Leucocyte s - - + - -Re sazurine + — — — 9 Sadie T.S. 11.4 11.7 10.5 10.8 11.0 11.8 11.7 11.7 H.3 11.3 11.32 SNF 8.3 8.3 8.1 8.2 8.0 8.4 8.3 8.4 8.3 8.2 8.25 1 .57 F 3.-1 3.4 2.4 2.6 3-0 3.4 3-4 3.3 3.0 3.1 3-07 11 .21 Leucocyte s + - - - * Re s a z u r i n - — — — — APPENDIX I I I R e s u l t s of milk t e s t s 1956-1957 H o l s t e i n s No. Name U N C N 2 0 s r r . i " . s-* S 8 S S g » s 2 s -> S 10 Snowball T.S. 11.9 11.9 11.4' 11.7 11.9 12.1 12.1 12.2 12.1 12.1 11.94 SNF 8.8 8.8 8.6 8.-7 8.8 8.7 8.8 8.8 8.8 8.8 8.76 1.48 F 3.1 3.1 2.8 3.0 3-1 3.4 3.3 3.4 3.3 3.3 3-18 5.25 Leucocytes g ' - + Resazurin + Average c o e f f i c i e n t of va r i a n c e f o r s o l i d s - n o t - f a t i s 2.14. Average c o e f f i c i e n t of variance f o r b u t t e r f a t i s 6.83. COVARIANCE CHART MODEL Animal Parents 1 + F 1 2 3 4 5 6 7 8 9 10. 1. Gladness 1.000 1.000 . 2 . R o s a l i n d - 1 . 0 0 0 0 . 0 0 0 1 . 0 0 0 3 . L a s s i e - 1.000 0.000 0.000 1.000 4 . Governor 2 X ? 1.000 0.000 0 . 5 0 0 0 . 000 1.000 5. Galahad 1 X ? 1.000 0 . 5 0 0 0.000 0. 000 0.000 1.000 6. S p i t f i r e 4 X 1 1.000 0 . 5 0 0 0 . 2 5 0 0. 000 0 . 5 0 0 0 . 2 5 0 1-. 000 7. Admiral 5 X 2 1.000 0 . 2 5 0 0 . 5 0 0 0. 000 0 . 2 5 0 0 . 5 0 0 0. 250 1.000 8. Commodore 7 X 1.062 0 . 2 5 0 0 . 3 1 2 0. 000 0 . 2 5 0 0 . 3 1 2 0. 375 0 . 5 6 2 1.062 9- White Cockade 6 X 3 1.000 0 . 2 5 0 0 . 1 2 5 0. 5 0 0 0 . 2 5 0 0 . 1 2 5 0. 500 0 . 1 2 5 0.187 1.000 10 • Peggy 7 X 1.062 0 . 1 2 5 0 . 2 5 0 0. 000 0 . 1 2 5 0 . 2 5 0 0. 125 0 . 5 0 0 0.281 0.062 1.062 & E x p l a n a t i o n f o r the covariance chart see Page 4 0 . - 78 -BIBLIOGRAPHY Aschaffenburg, R. and Rook, J.H. (1949). Review of the progress of d a i r y s c i e n c e . Journal of Dairy Research, V o l . 16, p. 390. B a i l e y , G.L. (1952 a ) . V a r i a t i o n s i n l a c t a t i o n y i e l d , m i l k - f a t percentage and s o l i d s - n o t - f a t percentage, t h a t are due to the age of the cow. Jo u r n a l of Da i r y Research, V o l . 19, p. 89-(1952 b ) . V a r i a t i o n of s o l i d s - n o t - f a t content i n milk due to stage i n l a c t a t i o n . J ournal of Dairy Research, V o l . 19, p. 102. (1952 c ) . V a r i a t i o n of s o l i d s - n o t - f a t / c o n t e n t i n milk due to season. J o u r n a l of Da i r y Research, V o l . 19, p. 109. (1952 d ) . Long term trends i n milk composition. Journal of D a i r y Research, V o l . 19, P« 115. (1952 e ) . V a r i a t i o n i n milk composition due to winter f e e d i n g p r a c t i c e . Journal of Da i r y Research, V o l . 19, p. 169. B a k a l o r , S. (1948). V a r i a t i o n of s o l i d s - . n o t - f a t i n mil k . Farming i n South A f r i c a , V o l . 23, p. 271. B a r n i c o a t , C.R., Logan, A.G., Grant, A.T. (1949). M i l k -s e c r e t i o n s t u d i e s with New Zealand Romney ewes. Parts I I I and IV. Journal of A g r i c u l t u r a l Science, V o l . 39• P« 237. B a r t l e t t , S. (1934 a ) . "The B e r k s h i r e Farmer's Year Book." London. G. G r i f f i n and Co. (1934 b ) . V a r i a t i o n s i n the s o l i d s - n o t - f a t content of mil k . I and I I . Journal of Da i r y Research, V o l . 5, p. 113. B a r t l e t t , S., F o l l e y , S.J., Rowland, S.J., Curnow, D.H. and Simpson, S.A. (1948). Oestrogens i n grass and t h e i r p o s s i b l e e f f e c t s on milk s e c r e t i o n . Nature, V o l . 162, p. 845. B a r t l e t t , S., G o l d i n g , J . , Wagstaff, A. (1932). The e f f e c t of season on the r e l i a b i l i t y of the percentage of s o l i d s - n o t -f a t i n milk, as c a l c u l a t e d by formulae. A g r i c u l t u r a l Progress, V o l . 9, P« 95» - 79 -B a r t l e t t , S. and Kay, H.D. (1950). M i l k q u a l i t y . Journal of Royal A g r i c u l t u r a l S o c i e t y of England. V o l . I l l , p. 87. B a r t l e t t , S., Rowland, S.J. and Thompson, S.R. (I949). I o d i n a t e d p r o t e i n f e e d i n g and milk composition. X l l t h I n t e r n a t i o n a l Dairy Congress 1949, Sect. 1, p. 102. B l a x t e r , K.L., Reineke, E.P., Crampton, E.W. and Petersen, W.E. (1949). The r o l e of t h y r o i d a l m a t e r i a l s and of s y n t h e t i c g o i t r o g e n s i n animal p r o d u c t i o n and an a p p r a i s a l of t h e i r p r a c t i c a l use. Journal of Animal Sci e n c e , V o l . 8, p. 307. Bonnier, G. and Hansspn, A. (I946). S t u d i e s on monozygous c a t t l e twins. V I I . On the g e n e t i c a l d e t e r m i n a t i o n of the interdepency between the percentages of f a t , p r o t e i n and l a c t o s e i n the mil k . Acta A g r i c u l t u r a e S c a n d i n a v i c a , V o l . 2, pp. 171-184. Bonnier, G., and Hansson, A. (1949). Further s t u d i e s on the g e n e t i c a l d e t e r m i n a t i o n of the composition of cow's milk with regard to f a t , p r o t e i n and l a c t o s e . Acta A g r i c u l t u r a e S c a n d i n a v i c a , V o l . 3, PP« 179-188. Bonnier, G., Hansson, A., S k j e r v o l d , H., and C a r l i , B. (1950) The g e n e t i c a l d etermination of the composition of l a c t o -p r o t e i n . Acta A g r i c u l t u r a e S c a n d i n a v i c a , V o l . 1, p. 1. B r i t i s h O i l and Cake M i l l s L t d . , London, (1955-1956). F i n a l Report. T h i r d B u l l Progeny T e s t . B a r l b y Farm - Selby -Yorks. C a u l f i e l d , W.L., Whitnah, C.H., and Atk i n s o n , F.W. (1939) M i l k composition. B u l l e t i n of I n t e r n a t i o n a l A s s o c i a t i o n of Milk D e a l e r s , V o l . 31, p. 6. Commonwealth Economic Committee. Annual Report 1955 • B r i t i s h Government, London. Cone, F . J . (1940). The. l e n c o c y t e count and the c h l o r i d e content of milk from Bovine udders with m i l d S t r e p t o c o c c i c i n f e c t i o n s . J o urnal of Mil k Technology, V o l . 3, p« 341. C r a n f i e l d , H.T. (1930). E f f e c t of abnormal weather c o n d i t i o n s on the q u a l i t y of mil k . Journal of the . M i n i s t r y of A g r i c u l t u r e (Great B r i t a i n ) . V o l . 37, p. 347* - 80 -C r a n f i e l d , H.T., G r i f f i t h s , D.G., and L i n g , E.R. (1927). The composition of milk, p a r t I and I I . Journal of A g r i c u l t u r a l S cience, V o l . 17, pp. 62-93. Crossman, J.V., Dodd, F.H., Lee, J.M., and Weave, F.K. (1950). The e f f e c t of b a c t e r i a l i n f e c t i o n on the m i l k y i e l d of the i n d i v i d u a l q u a r t e r s of the cow's : udder. J o u r n a l of Dairy Research, V o l . 17, p. 128. Davel, H.B. (1947). N u t r i t i o n a l Studies of Dairy C a t t l e . Farming i n South A f r i c a , V o l . 22, p. 242. Davies, W.L. (1939). "The chemistry of milk". London. Chapman and H a l l Davis, R.N., Harland, F.G., Caster, A.B. and K e l l n e r , R.H. (1947). V a r i a t i o n i n the c o n s t i t u e n t s of milk under A r i z o n a c o n d i t i o n s . I. V a r i a t i o n s of i n d i v i d u a l cows w i t h i n breeds by calendar months. Jo u r n a l of Dairy Science, V o l . 30, p. 415• Drakeley, T.J. and White, M.K. (1927). The i n f l u e n c e of the stage of l a c t a t i o n and the breed of the cow on the y i e l d and q u a l i t y of the m i l k . J o u r n a l of A g r i c u l t u r a l Science, V o l . 17, p. 118. F a b r i s , A. (1951). Seasonal v a r i a t i o n of s o l i d s - n o t - f a t i n m i l k . Hondo L a t t e , V o l . 8, p. 460. F l u x , D.S., P a t c h e l l , M.R., Campbell, T.L., McDowall, F.H. (1955). V a r i a t i o n s i n the composition of milk. The D a i r y Research I n s t i t u t e i n New Zealand, P u b l i c a t i o n Wo. 277« F o l l e y , S.J., Watson, H.M., and Bottomley, A.C. (1941). Experiments on the chemical enrichment of cow's milk by the a d m i n i s t r a t i o n of d i e t h y l s t i l b e s t e r o l and i t s d i p r o p i o n a t e . Journal of Dairy Research, V o l . 12, p. 1. Gaines, W.L. (1928). An e f f i c i e n c y formula f o r d a i r y cows. Scien c e , V o l . 67, p. 353. Gaines, W.L., and Davidson, F.A. (1923). R e l a t i o n between percentage f a t content and y i e l d of m i l k . B u l l e t i n I l l i n o i s A g r i c u l t u r a l Experimental S t a t i o n 245. G o l d i n g , J. (1934). M i l k A n a l y s i s . A n a l y s t , V o l . 59, p. 468. Goss, E.F. (1953). "Techniques of Dairy Plant T e s t i n g . " The Iowa State C o l l e g e Press. Ames, Iowa. - 81 -Gowen, J.W. (1919)' V a r i a t i o n s and mode of s e c r e t i o n of milk s o l i d s . Journal of A g r i c u l t u r a l Research, V o l . 16, P- 79-Hayes, W.P. (1926). The e f f e c t of environmental temperature on the percentage of f a t i n cow's m i l k . Journal of Dairy Science, V o l . 9, p. 219. Hancock, J. (1953). S t u d i e s i n monozygotic c a t t l e twins. New Zealand J o u r n a l of Science and Technology, V o l . 35 A, p. 67. Hansson, A., S k j e r v o l d , H., and B. C a r l i , Bonnier, G. (1950). The g e n e t i c a l d e t e r m i n a t i o n of the composition of l a c t o -p r o t e i n . Acta A g r i c u l t u r a e S c a n d i n a v i c a , V o l . 1, p. 1. Hansson, A. (1948 a ) . Studi e s on monozygous c a t t l e twins. X. The e f f e c t of feeding excessive amounts of calcium and phosphorous to m i l k i n g cows. Acta A g r i c u l t u r a e S c a n d i n a v i c a , V o l . 3, pp. 59-70. (1948 b ) . S t u d i e s on monozygous c a t t l e twins. XI. The e f f e c t of premature p a r t u r i t i o n on udder development and milk s e c r e t i o n . Acta A g r i c u l t u r a e S c a n d i n a v i c a , V o l . 3, PP. 71-74. (1949). The g e n e t i c a l d e t e r m i n a t i o n of the composition of cow's m i l k with regard to f a t , p r o t e i n and l a c t o s e . X l l t h I n t e r n a t i o n a l Dairy Congress, Stockholm, 1949, V o l . 1, s e c t . 1, pp. 386-391. Hansson, A., and Bonnier, G. (1949). F u r t h e r s t u d i e s on the g e n e t i c a l d e t e r m i n a t i o n of the composition of cow's milk with regard to f a t , p r o t e i n and l a c t o s e . Acta A g r i c u l t u r a e S c a n d i n a v i c a , V o l . 3> PP• 179-188. Hansson, A., and S k j e r v o l d , H., and C a r l i , B. (1949). Den d a g l i g a v a r i a t i o n e n i mjolkens sammansattning. The d a i l y v a r i a t i o n of milk p r o d u c t i o n ( E n g l i s h summary). Lantbr. akad. t i d s k r . 88, pp. 287-294. H a z e l , L.N. (1943). The g e n e t i c b a s i s f o r c o n s t r u c t i n g s e l e c t i o n indexes. G e n e t i c s , V o l . 28, p. 476. H a z e l , L.N., and T e r r i l l , C E . (1951). H e r i t a b i l i t y of weaning weight and s t a p l e l e n g t h i n range Rambouillet lambs. Journal of Animal Science, V o l . 4, p. 347. - 82 -Holmes, W. , Waite, R., MacLusky, S.O. and Watson, J.N. 91956). Winter fe e d i n g of d a i r y cows. J o u r n a l of Dairy Research, V o l . 23, p. 1. Houston, J . , and Hale, R.W. (1932). The y i e l d and composition of m i l k with s p e c i a l r e f e r e n c e to the i n f l u e n c e of c l i m a t i c c o n d i t i o n s and other f a c t o r s . J o u r n a l of Dairy Research, V o l . 3, p. 294. Jack, E.L. (1951)« R e l a t i o n s h i p of s o l i d s - r i o t - f a t to f a t i n C a l i f o r n i a milk. C a l i f o r n i a A g r i c u l t u r a l Experiment S t a t i o n , B u l l e t i n 726. Jacobson, M.S. (I936). B u t t e r f a t and t o t a l s o l i d s i n New England Farmers' milk as d e l i v e r e d to p r o c e s s i n g p l a n t s . J o u r n a l of Dairy Science, V o l . 19, P • 171» J a r l , F. (1946). S t u d i e s on monozygous c a t t l e twins. VI. I n v e s t i g a t i o n s i n t o the q u a n t i t a t i v e v a r i a t i o n of a s c o r b i c a c i d i n the milk. Acta A g r i c u l t u r a e S c a n d i n a v i c a , V o l . 1, pp. 207-238. L a r s s o n , E.L., and P l a t o n , J.B., and Thome, K.E., and Hanssom, A. (1949)' The i n f l u e n c e of h e r e d i t y on the connection between the percentage of f a t and p r o t e i n i n m i l k . X l l t h I n t e r -n a t i o n a l Congress, Stockholm, 1949, V o l . 1, s e c t . 1, PP. 377-385. Kay, H.D. (1948). M i l k q u a l i t y . S a n i t a r i a n , V o l . 56, p. 322. Kay, H.D. (1956). Compositional q u a l i t y . The milk producer's problem. The A g r i c u l t u r a l Review. V o l . I I , No. 3, pp. 12-17. King, S.C., Henderson, C R . (1954). Variance components a n a l y s i s i n h e r i t a b i l i t y s t u d i e s . P o u l t r y Science, V o l . 33, p. 147. Legg, S.P., Curnow, D.H., and Simpson, S.A. (I950). The seasonal and s p e c i e s d i s t r i b u t i o n of oestrogen i n B r i t i s h p a s t u re. Biochemistry J o u r n a l , V o l . 46, p. 19-L i n g , E.R. (1945) " D a i r y Chemistry" 2nd e d i t i o n . London: Chapman and H a l l . Lush, J.L. (1935). The i n h e r i t a n c e of p r o d u c t i v i t y i n farm l i v e s t o c k . Empire Journal of Experimental A g r i c u l t u r e , V o l . 3, p. 25. - 83 -Lush, J.L. (1940). I n t r a - s i r e c o r r e l a t i o n s or r e g r e s s i o n s of o f f s p r i n g on dam as a method of e s t i m a t i n g h e r i t a b i l i t y of c h a r a c t e r i s t i c s . The American S o c i e t y of Animal P r o d u c t i o n , Proceedings, p. 293-McDowall, F.H. (1945)• S t u d i e s on the d e t e c t i o n of m a s t i t i s i n New Zealand d a i r y herds. New Zealand J o u r n a l of Science and Technology, V o l . 27A, p. 258. Neave, M., P h i l l i p s , M., and M a t t i c k , A. (1952). C l i n i c a l m a s t i t i s i n s i x herds f r e e d from s t r e p t o c o c c u s a g a l a c t i a e . Overman, (1939)• Composition of milk of Brown Swiss cows with summary of data on the composition of milk from cows of other d a i r y breeds. I l l i n o i s A g r i c u l t u r a l Experimental S t a t i o n B u l l e t i n 457. Provan, A.L. (1949)» I n v e s t i g a t i o n s i n t o the composition of m i l k . X l l t h I n t e r n a t i o n a l Dairy Congress 1949, sect. 2, p. 217. Provan, A.L. (1950). V a r i a t i o n s i n the milk composition. Journal of B r i t i s h D airy Farmers' A s s o c i a t i o n , V o l . 54, p. 33. Provan, A.L., and Jenkins, D.T. (1949). Trends i n m i l k q u a l i t y . J o urnal of the S o c i e t y of Dairy Technology, V o l . 2, p.- 88. Ragsdale, A.C. and Brody, S. (1922). The e f f e c t of temperature on the percentage of f a t i n m i l k . A f i r s t r e p o r t . Journal of Dairy Science, V o l . 5, p- 212. Regan, W.M., and Richardson, G.A. (I938). Reactions of the d a i r y cow to changes i n environmental temperature. Journal of Dairy Science, V o l . 21, p. 73• Richmond, H.D. (1920). "Dairy Chemistry" 3rd e d i t i o n . London: G. G r i f f i n and Co. R i d d e t , W., Campbell,. T.L., McDowall, F.H., and Cox, G.A. (1941). The r e l a t i o n of plane of n u t r i t i o n t o milk p r o d u c t i o n and milk composition i n New Zealand. New Zealand Journal of Science and Technology, V o l . 23A, p. 80. R i d d e t , W., Campbell, T.L., McDowall, F.H., and Cox, G.A. (1954). The r e l a t i o n of plane of n u t r i t i o n to milk p r o d u c t i o n and m i l k composition i n New Zealand. New Zealand J o u r n a l of Science and Technology, V o l . 34A, p. 238. - 84 -Robertson, A. (1956). V a r i a t i o n s i n the chemical composition of milk with p a r t i c u l a r r e f e r e n c e to the s o l i d s - n o t - f a t . Journal of Dairy Research, V o l . 23, p. 82. Rowland, S.J. (I938). The p r o t e i n d i s t r i b u t i o n i n normal and abnormal milk. J o u r n a l of Dairy Research, V o l . 9, p. 47. Rowland, S.J. (I942). S u b c l i n i c a l m a s t i t i s . Chemistry and I n d u s t r y . London. V o l . 61, p. 252. Rowland S.J. (1944). The occurrence i n winter of milk with a low content of s o l i d s - n o t - f a t . J ournal of Dairy Research, V o l . 13, p. 261. Rowland, S.J. (1946). The e f f e c t of l e v e l of f e e d i n g on the s o l i d s - n o t - f a t content i n milk. Dairy I n d u s t r i e s , V o l . 11, p. 656. Rowland, S.J. and Scott B l a i r , G.W. (1949)« B i e n n i a l Reviews of the Congress of Dairy Science. J o u r n a l of D a i r y Research, V o l . 13, p- 93. Rowland, S.J. and Z e i n - e l - D i n e (1938). The e f f e c t of sub-c l i n i c a l m a s t i t i s on the s o l i d s - n o t - f a t content of m i l k . J o u r n a l of Dairy Research, V o l . 9, P« 182. Rowland, S.J., and Z e i n - e l - D i n e (1939). The value of i n d i r e c t methods f o r the d e t e c t i o n of m a s t i t i s . The c a s e i n number f o r d i a g n o s i s of m a s t i t i s . J ournal of Da i r y Research, V o l . 1G, p. 108 and p. 267. Tocher, J.F. (1928). V a r i a t i o n s i n the composition of milk. Edinburgh: Government 1928, p. 195. Turner, C.W. (1936). Studies of v a r i a t i o n i n milk composition. . B u l l e t i n of the U n i v e r s i t y of Minnesota, No. 365. Van Rensburg, S.W. (1946). L o w - s o l i d s - n o t - f a t content of milk i n South A f r i c a . Farming i n South A f r i c a , V o l . 21, p. 217. Vanlandingham, A.H., Weakley, C.E., Moore, E.N., and Henderson, H. 0. (1940). The r e l a t i o n s h i p of the development of m a s t i t i s to changes i n the c h l o r i d e , l a c t o s e and c a s e i n number of mil k . Journal of Dairy Science, V o l . 24, p. 383* Waite, R., White, CD., and Robertson, A. (1956). V a r i a t i o n s i n the chemical composition of milk with p a r t i c u l a r r e f e r e n c e to the s o l i d s - n o t - f a t . Journal of Dairy Research, V o l . 23, p. 65. - 85 -Weaver, E., and Matthews, C A . (1928). The i n f l u e n c e of temperature and c e r t a i n other f a c t o r s upon the percentage of f a t i n mi l k . Research B u l l e t i n Iowa State C o l l e g e 107. White, M.K., and Drakeley, T.J. ( 1 9 2 7 ) . The i n f l u e n c e of the age of the cow on the y i e l d and q u a l i t y of the m i l k . J o u r n a l of A g r i c u l t u r a l Science, V o l . 17, p. 420. Wright, S., ( 1 9 3 9 ) ' Genetic p r i c i p l e s governing the r a t e of progress of l i v e s t o c k breeding. The American S o c i e t y of Animal P r o d u c t i o n , Proceedings, p. 18T Wright, S. ( 1 9 2 i ) . Systems of mating. G e n e t i c s , V o l . 6 p. 111. 

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