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Relationships between growth rate, feed efficiency, carcass quality and certain organ weights in swine Bowden, David M. 1957

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RELATIONSHIPS BETWEEN GROWTH RATE. FEED EFFICIENCY. CARCASS  QUALITY AND CERTAIN ORGAN WEIGHTS' IN 'SWINE. D.M. Bowden A Thesis Submitted i n P a r t i a l F u l f i l m e n t of the Requirements f o r the Degree of MASTER OF SCIENCE IN AGRICULTURE i n the Department of Animal Science We accept t h i s t h e s i s as conforming to the standard r e q u i r e d from candidates f o r the degree of MASTER OF SCIENCE IN AGRICULTURE Members d f the Department of Animal Science THE UNIVERSITY OF BRITISH COLUMBIA APRIL, 1957 T H E S U P E R I N T E N D E N T E X P E R I M E N T A L F A R M S S E R V I C E C A N A D A D E P A R T M E N T O F A G R I C U L T U R E E X P E R I M E N T A L F A R M . A G A S S I Z , B . C . l£th August, 1957. L i b r a r i a n , U n i v e r s i t y of B r i t i s h Columbia, Vancouver* 8, B.C. Dear S i r , .. In my M.S.A. t h e s i s e n t i t l e d " R e l a t i o n s h i p s between growth r a t e , f e e d e f f i c i e n c y , carcass q u a l i t y and c e r t a i n organ weights i n swine" I have discovered two e r r o r s . On Page hfi i n Table ll| the c o r r e l a t i o n of "Peed/carcass and l a r g e i n t e s t i n e " f o r Group C should be - .21 r a t h e r than .21." Also on page 52 i n Table 16 the r e g r e s s i o n of "Peed/carcass gain on l a r g e i n t e s t i n e " f o r Group C should be -5.52 r a t h e r than 5.52. I am sorry that t h i s has occurred. I hope that i t can be cor r e c t e d by use of an e r r a t a sheet. This t h e s i s was submitted to you i n A p r i l , 1957. Yours very t r u l y , DMB/EC D,M, Bowden Animal Husbandman. - i v -ABSTRACT The object of t h i s study was to consider e f f e c t s of t r e a t -ment on and r e l a t i o n s h i p s among, c e r t a i n , economic c h a r a c t e r i s t i c s , and organ weights i n purebred Y o r k s h i r e market hogs. Included are measurements on 132 pigs from three experiment-a l groups. Economic c h a r a c t e r i s t i c s measured were; r a t e of gain, dressing percentage, feed per u n i t g a i n , l e a n c u t s , f a t cuts and b e l l y . Organs weighed were h e a r t , l i v e r , spleen, stomach, small i n t e s t i n e , l a r g e i n t e s t i n e and adrenals. In the t e s t of forage u t i l i z a t i o n pasture f e d pigs grew slower, produced leaner carcasses and had heavier h e a r t s , spleens and stomachs than those f e d i n d r y l o t . In the two t e s t s of d r i e d apple pomace u t i l i z a t i o n a d d i t i o n of 20% pomace had no s i g n i f i c a n t e f f e c t s on the c h a r a c t e r i s t i c s or organs measured. Increasing the l e v e l to 40%, however, r e -s u l t e d i n slower growth, g r e a t e r feed consumption per u n i t g a i n , lower dressing percentage, leaner carcass, heavier l i v e r and heavier l a r g e i n t e s t i n e . P h y s i o l o g i c a l aspects of c o r r e l a t i o n s and regr e s s i o n s among the c h a r a c t e r i s t i c s and organs are discussed as are the i n f l u e n -ces of treatments on these r e l a t i o n s h i p s . In presenting 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 of the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that 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 reference and study. I f u r t h e r agree that permission f o r extensive copying of 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 granted by the Head of my Department or by h i s r e p r e s e n t a t i v e . I t i s understood that copying or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l gain s h a l l not be allowed without my w r i t t e n permission. Department of .The U n i v e r s i t y of B r i t i s h Columbia Vancouver 3. Canada. Date - i -AKN OWLEDG EMEN T The author wishes to take t h i s opportunity to express h i s sincere a p p r e c i a t i o n to Dr. J.C. Berr y of the Department of Animal Science f o r h i s encouragement and a s s i s t a n c e i n the prep-a r a t i o n of t h i s t h e s i s . A l s o to Dr. D.W. Blackmore of the Ex-perimental Farm, Agassiz f o r h i s encouragement and a s s i s t a n c e i n c o l l e c t i o n of the data, s t a t i s t i c a l treatment of the data and c r i t i c i s m of the manuscript. S p e c i a l thanks to members of the Agassiz Farm s t a f f , espec-i a l l y R. Rodger, Herdsman f o r a s s i s t a n c e i n the sometimes un-pleasant job of c o l l e c t i n g data. The author i s indebted t o the management and s t a f f of the pl a n t of Clappison Packers Ltd!.., Haney, B.C. who have been so very cooperative at a l l times. - i i -TABLE OF CONTENTS Page I . . LITERATURE REVIEW 1 A. Economic C h a r a c t e r i s t i c s 1 -1. Growth r a t e 1 2. Feed e f f i c i e n c y :5 3. Dressing percentage 7 4. Carcass q u a l i t y 8 B. Organs 13 1. D i g e s t i v e t r a c t . . 13 2. Heart . . . 15 3. L i v e r 17 4. Spleen 19 5. Adrenal 20 C. R e l a t i o n s h i p s 22 1. Between economic c h a r a c t e r i s t i c s 22 2. Between economic c h a r a c t e r i s t i c s and organs. . 24 3. Between organs 24 I I . MATERIALS AND METHODS 26 A. Animals 26 B. Treatments. . 26 1. Group A /summer 1955) 26 2. Group B (winter 1 9 5 5 - 5 6 ) . . . . 28 3. Group C (summer 1956) 29 C. Feed and Body Weight Records 30 D. Slaughtering and Organ Weights. . . . 32 E. Carcass C u t t i n g and Weighing . . . . 32 F. Treatment of Data 33 I I I . RESULTS . 35 A. A n a l y s i s of Variance 35 1. Group A 3 5 - i i i -2. Group B 35 3. Group C . . 36 B. A n a l y s i s of Covariance 36 1. C o r r e l a t i o n s 36 2. Regressions 36 IV. DISCUSSION . . 56 A. Sex E f f e c t s 56 B. Treatment E f f e c t s 57 1. Group A 57 2. Group B 59 3. Group C 60 C. R e l a t i o n s h i p s 63 1. C o r r e l a t i o n s . w i t h i n treatments 63 2. C o r r e l a t i o n s between treatments 68 3. Regressions w i t h i n '. treatments ... . 70 4. Regressions between treatments 70 5. A p p l i c a t i o n of r e l a t i o n s h i p i n swine breeding. . . . . . . 71 V. SUMMARY 73 VI. LITERATURE CITED 75 INTRODUCTION A greater understanding of f u n c t i o n a l r e l a t i o n s h i p s i n the animal "body would seem to he of value i n developing animals f o r higher production. I t i s not w e l l known what r e l a t i o n s h i p s are optimum under a given set of c o n d i t i o n s f o r growth, f a t t e n i n g or reproduction. This i n f o r m a t i o n could he of great value to the animal n u t r i t i o n i s t who has become conscious of the need f o r g reater e f f i c i e n c y of feed u t i l i z a t i o n and higher production, More knowledge of r e l a t i o n s h i p s would a i d the animal breeder to determine the l i m i t s of applying s e l e c t i o n . I t . might help answer the question as to how many c h a r a c t e r i s t i c s should be s e l e c t e d f o r at one time to g i v e the g r e a t e s t improvement. In meat-producing animals the p r i n c i p a l i n t e r e s t l i e s i n the production of the g r e a t e s t amount of l e a n meat per u n i t of feed consumed. Many f a c t o r s can i n f l u e n c e the amount and pro-p o r t i o n of l e a n meat l a i d down on the animal carcass. Research work has shown that both breeding and feeding can i n f l u e n c e the p r o p o r t i o n of l e a n meat i n the hog carcass. The f o l l o w i n g study i s designed to g a i n some f u r t h e r know-ledge of the r e l a t i o n s h i p s e x i s t i n g between growth r a t e , feed consumption, carcass c h a r a c t e r i s t i c s and organ s i z e i n the Y o r k s h i r e market hog. The raw data used i n t h i s study are deposited at the Dominion Experimental Farm, Ag a s s i z , B.C. Included i n these are more than 2000 measurements. 1 I.LITERATURE REVIEW A. Economic C h a r a c t e r i s t i c s 1. Growth r a t e Rate of body weight g a i n has been used f o r many years as an important experimental c r i t e r i o n i n assessing both genetic and n u t r i t i o n a l d i f f e r e n c e s i n groups of meat-producing animals. The f a c t o r s i n f l u e n c i n g growth r a t e are so numerous th a t a comp-l e t e d i s c u s s i o n w i l l not be attempted here. We s h a l l d e a l r a t h -er w i t h those f a c t o r s which are of g r e a t e s t i n t e r e s t i n swine production. Breeding has been shown to i n f l u e n c e growth r a t e . In a study i n v o l v i n g 8 breeds of swine, Miranda et a l (1946) found h i g h 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 r a t e of g a i n between breeds and between l i t t e r s w i t h i n breeds. Comstock et a l (1944) observed growth r a t e d i f f e r e n c e s between the Poland China and Minnesota No. 1 breeds. S t o t h a r t (1938) found d i f f e r e n c e s b e t -ween s t r a i n s of Canadian Y o r k s h i r e s . Johansson and Korkman, ( c i t e d by Blackmore, ,1953), using data c o l l e c t e d at Swedish swine t e s t i n g s t a t i o n s revealed that Landrace pigs had a higher r a t e of g a i n than Large Whites. However, no s i g n i f i c a n t d i f f e r -ences between Landrace and Large Whites could be found i n data from Danish t e s t i n g s t a t i o n s as reported by Lush (1936). Blackmore (1953) found a tendency, though n o n - s i g n i f i c a n t , f o r breed c l a s s e s c o n t a i n i n g h i g h perecntages of Landrace and / or Poland China to grow f a s t e r than those of mainly Duroc and /or Chester White breeding. Warren and Dicker son (1952), studying 2 l i n e s of Poland China, Hampshire, Y o r k s h i r e and Duroc Jersey swine, found s i g n i f i c a n t d i f f e r e n c e s i n r a t e of g a i n between s i r e l i n e s as w e l l as dam l i n e s . Type of p i g may a l s o have some i n f l u e n c e . Z e l l e r (1944) found that intermediate pigs f e d to approximately 225 l b s . gained about 0.17 l b s . more per day than small type p i g s and 0.09 l b s . more than l a r g e - t y p e pigs fed to the same weight. Seasonal e f f e c t s have a l s o been noted. Dunlop and West (1942) sho?/ed that temperature can i n f l u e n c e r a t e of g a i n . Cold weather reduced growth r a t e i n a study by Crampton and Ashton (1946a). Temperatures above 73° F produced slower gains i n pigs between 70 and 144 l b s . and temperatures above 60°F produced slower gains i n pigs over 166 l b s . i n a study by H e i t -man and Hmghes (1949). Only temperatures above 40°F were stud.*-,' i e d . Blunn and Baker (1947) noted l a r g e seasonal d i f f e r e n c e s i n r a t e of g a i n a l s o . Growth r a t e apparently d i f f e r s between sexes. Lacy (1932) and Donald (1940) r e p o r t f a s t e r growth i n male p i g s . S ex d i f f -erences i n r a t e of growth from weaning to slaughter were .039 l b s . per day f o r the Poland China breed and .089 l b s . per day f o r the Minnesota No. 1 i n work by Comstock e_t a l (1944) . Yo r k s h i r e barrows gained s i g n i f i c a n t l y f a s t e r than g i l t s i n work by Crampton and fishton (1946a) and Bennett and Coles (1946) However, no mention i s made i n the l a t t e r work of c o r r e c t i o n s f o r season, year or r a t i o n d i f f e r e n c e s which are contained i n t h e i r data. Fredeen (1953) found that females took 5.4 days longer to reach market weight than males. Ten to f i f t e e n per-3 cent f a s t e r gains i n males were obtained by Crampton and Ashton (1945) w i t h the g r e a t e s t d i f f e r e n c e between sexes occurr-ing i n the f a t t e n i n g p e r i o d from 110 l b s . to 200 l b s . Despite f i n d i n g a h i g h l y s i g n i f i c a n t d i f f e r e n c e i n r a t e of g a i n between sexes, Miranda et a l (1946) f e l t t h a t the e f f e c t s of sex were hardly worth considering when a l l o t i n g to feeding t r i a l s . Danish workers have not found l a r g e enough d i f f e r e n c e s to consider c o r r e c t i n g g a i n f o r sex e f f e c t under t h e i r p i g t e s t i n g program ( c i t e d by Blackmore, 1953). Growth r a t e may be i n f l u e n c e d by weight and age at the beginning of the recording p e r i o d . These f a c t o r s are discussed f u l l y by Brody (1945). Miranda e t a l (1946) concluded t h a t i n i t i a l weights on experimental t r i a l s were worthwhile c o n s i d e r ing only when they v a r i e d w i d e l y . They found that the c o r r e l a t -i o n between i n i t i a l weight and f u t u r e gains v a r i e d w i t h l e n g t h of the feeding p e r i o d and i n i t i a l age of pigs when reco r d i n g p e r i o d s t a r t e d . P r o t e i n has been a n u t r i t i o n a l f a c t o r q u i t e widely s t u d -i e d as to i t s e f f e c t on r a t e of ga i n . E l l i s and Hankins (1935) demonstrated that a r a t i o n c o n t a i n i n g 18.9% p r o t e i n gave f a s t e r g a i n than r a t i o n s c o n t a i n i n g 15.4% and 12.4% p r o t e i n . In a study of r a t i o n s containing p r o t e i n l e v e l s of 10, 12, 14, 16, 18 and 20% Jensen et a l (1955) found that average d a i l y gains reached a maximum between 16 and 18% p r o t e i n without a n t i b i o t i c s and at 14% w i t h e i t h e r terramycin or aureomycin fed as an a n t i -b i o t i c . In f u r t h e r vrork on p r o t e i n l e v e l s Speer et. a l (1956) observed that a maximum r a t e of g a i n was reached at 16% up t o 4 75 l b s . and 14% i f fed at one l e v e l throughout the t e s t p e r i o d from weaning u n t i l 200 l b s . Crampton and Ashton (1946a) found that reducing p r o t e i n from animal source down to 1.4% of the t o t a l r a t i o n d i d not A f f e c t r a t e of g a i n i n swine. This f i n d i n g i s supported by a second study, Crampton and Ashton (1946b) i n which no difference i n r a t e of g a i n occurred when animal p r o t e i n was fed at l e v e l s of 0.5, 10, and 20% of the t o t a l p r o t e i n i n the r a t i o n . Influence of high f i b e r feeds on gains i n swine has rec e i v e d some a t t e n t i o n i n recent y e a r s . In a study of crude f i b e r l e v e l s Axelsson and E r i k s s o n (1955) used wheat straw i n r a t i o n s balanced i n a l l other respects to giv e crude f i b e r l e v e l s from 4.8 to 9.3% of the r a t i o n dry matter. Crude f i b e r content of 6.57% was found to be optimum f o r weight g a i n w i t h higher l e v e l s g i v i n g decreased g a i n . Teague and Hanson (1954) obtained decreased r a t e of g a i n at high l e v e l s of crude f i b e r . P igs r e c e i v i n g 10 to 30% of a l f a l f a i n t h e i r r a t i o n s d i f f e r e d l i t t l e i n r a t e of g a i n i n t e s t s by Bohman e t a l (1953). A l f a l f i . l e v e l s above 30% however tended to reduce g a i n s . A l a t e r study by Bohman et a l (1955) using a l f a l f a l e v e l s of 0, 10, 30 and 50% showed reduced r a t e of g a i n w i t h each increase i n a l f a l f a . A number of a n t i b i o t i c s have re c e i v e d a great deal of a t t e n t i o n i n recent years due to t h e i r a b i l i t y to s t i m u l a t e growth under c e r t a i n circumstances. Braude, Wallace and Cunha (1953) have reviewed e x t e n s i v e l y the l a r g e number of papers published on a n t i b i o t i c s i n swine n u t r i t i o n . The i n f l u e n c e of a n t i b i o t i c s on r a t e of g a i n i s apparently determined by the 5 c l i n i c a l or s u b c l i n i c a l i n f e c t i o n s present i n the pigs to which they are f e d . This would account f o r the great v a r i a b i l i t y i n r e s u l t s obtained by d i f f e r e n t workers and by the same workers w i t h d i f f e r e n t groups of p i g s . Synthetic hormone preparations are at present being widely t e s t e d f o r t h e i r i n f l u e n c e on growth r a t e . A h i g h l y s i g n i f i c a n t growth depression i n pigs f e d from 51 l b s . to 220 l b s . and r e c e i v i n g 27 mg. or more of methyl testosterone per day was reported by Perry e_t a l (1956). 2. Feed e f f i c i e n c y There i s a p o s i t i v e r e l a t i o n s h i p between r a t e of g a i n and feed e f f i c i e n c y . Thus, the f a s t e s t g a i n i n g p i g i n most instances has the lowest feed consumption per u n i t of body g a i n Evvard e_t a l (1927) obtained a c o r r e l a t i o n of -.59 between d a i l y g a i n and feed requirements w i t h data from the Iowa State College herd. Rapid growth, low feed requirements and r a p i d f a t d e p o s i t i o n were found to be p o s i t i v e l y a s s o c i a t e d by Dick-erson (1947). A l l the f o l l o w i n g workers, who have been mention-ed p r e v i o u s l y i n t h i s study, have a l s o demonstrated t h i s p o i n t ; E l l i s and Hankins (1935), S t o t h a r t (1938), Dunlop and West (1942), Z e l l e r (1944), Fredeen (1953), Teague and Hanson (1954), Bohman e_t a l (1955) and Speer et a l (1956). The strong r e l a t i o n s h i p between g a i n and feed requirement i s a t t r i b u t e d by most workers to the lower feed requirement f o r maintenance of the f a s t e r , growing animal. Evvard et a l (1927) found that spring pigs r e q u i r e d l e s s feed /100 l b s . body g a i n than f a l l p i g s . These workers a l s o 6 noted that an increase i n i n i t i a l weight r e s u l t e d i n an increase i n feed r e q u i r e d per 100 l b s . g a i n . The l a t t e r p o i n t i s support-ed i n work noted by Z e l l e r (1947) where r a t e of g a i n and feed e f f i c i e n c y were stud i e d at 50 l b . i n t e r v a l s from 75 l b s . up to 374 l b s . l i v e weight. These r e s u l t s given i n Table 1, show th a t feed r e q u i r e d per u n i t g a i n increased r a p i d l y i n pi g s as body weight increased. TABLE 1 Gain and Feed U t i l i z a t i o n of Pigs at Various Body Weights Weight I n t e r v a l No. of pigs on t e s t Average g a i n d a i l y Feed per 50 l b s . l i v e - w t . g a i n l b s . l b s . l b s . 75-124 42 1.62 167 125-174 42 1.75 190 175-224 34 1.71 206 225-274 26 1.65 223 275-324 18 1.46 252 325-374 9 1.31 276 F i b e r l e v e l i n the r a t i o n was found by Axelsson and E r i k s s o n (1953) to i n f l u e n c e feed e f f i c i e n c y . They determined the optimum f i b e r l e v e l f o r feed e f f i c i e n c y to be 7.26% of the r a t i o n dry matter wh i l e the optimum f o r r a t e of g a i n was 6.57%. Ll o y d and Crampton (1955) t e s t e d f i b e r l e v e l s ranging from 1.4 to 8.6% and found that i n c r e a s i n g f i b e r l e v e l decreased the 7 apparent d i g e s t i b u l i t y of p r o t e i n by barrow p i g s . Teague and Hanson (1954) obtained s i m i l a r r e s u l t s . Crampton and Ashton (1946b) d i d not o b t a i n any d i f f e r e n c e i n feed e f f i c i e n c y from r e p l a c i n g p l a n t p r o t e i n w i t h animal p r o t e i n i n swine r a t i o n s . I n j e c t i o n of p u r i f i e d a n t e r i o r p i t u i t a r y growth hormone i n t o barrow pigs r e s u l t e d i n lower feed requirement per u n i t g a i n although growth r a t e was not s i g n i f i c a n t l y a f f e c t e d i n work by Turman and Andrews (1955). Bridges et a l (1952) obtained g r e a t e r e f f i c i e n c y of feed u t i l i z a t i o n per 100 l b s . g a i n when feeding p e n i c i l l i n , s t r e p t o -mycin or a combination o f the two i n swine r a t i o n s . 3. Dressing percentage N u t r i t i o n has been found to i n f l u e n c e dressing percentage i n some cases. Wilson et a l (1953), w i t h pigs f e d on p r o t e i n l e v e l s of 20, 17 and 14% from 45 to 75 l b s . of 16, 13 and 11% from 75 to 150 l b s . and of 12, 10 and 9.5% above 150 l b s . ob-tai n e d s i g n i f i c a n t l y higher dressing percents on the two lower l e v e l s . Catron et a l (1952) using p r o t e i n l e v e l s of 20, 18, 16 and 14|! w i t h 3% reductions i n each l e v e l at 75 and 150 l b s . l i v e weight, however, found no e f f e c t on dres s i n g percent at any l e v e l e i t h e r w i t h or without aureomycin. High f i b e r r a t i o n s apparently decrease dressing percent. Coey and Robinson (1955) found t h a t h i g h - f i b e r d i e t s gave lower dressing percents. Increasing a l f a l f a l e v e l decreased dressing percent i n work by Bohman e_t a l (1955). Harrington and Taylor (1955) obtained higher d r e s s i n g 8 percentages w i t h aureomycin supplement than w i t h p e n i c i l l i n . They a l s o obtained higher dressing percentages w i t h animal pro-t e i n than w i t h vegetable p r o t e i n i n the hog r a t i o n . G i l t s fed from 115 l b s . to slaughter on 50% of the energy intake of f u l l - f e e d i n g dressed at 76.4% w h i l e those on f u l l -feed dressed at 78.7% i n work by Haines et a l (1956). Wilcox et a l (1953) increased dressing percent s i g n i f i c a n t -l y i n hogs by. feeding sucrose before slaughter. I t i s thought that t h i s increase occurred mainly as a r e s u l t of increased carbohydrate i n the muscle t i s s u e . A p o s s i b l e breeding d i f f e r e n c e i n d r e s s i n g percent i s noted i n data reported by Fraser and S t o t h a r t (1947) from a number of Canadian s t a t i o n s t e s t i n g Landrace and Y o r k s h i r e hogs. Landrace were found to have a s l i g h t l y lower dressing percent than Y o r k s h i r e s . Although the d i f f e r e n c e was small i t was con-s i s t e n t i n the groups st u d i e d . Lush (1936) a l s o r e p o r t s d i f -ferences between Danish Landrace and Y o r k s h i r e s . Lacey (1932) d i d not f i n d s i g n i f i c a n t d i f f e r e n c e s between sexes i n dressing percent. This r e s u l t corresponds w i t h t h a t from other workers. Turman and Andrews (1955) obtained lower dressing pereents f o r pigs i n j e c t e d w i t h a n t e r i o r p i t u i t a r y growth hormone as compared to non-injected c o n t r o l s . 4. Carcass q u a l i t y Carcass q u a l i t y has become a very important c o n s i d e r a t i o n i n swine production. Emphasis i n both breeding and feeding i s placed on production of carcasses c o n t a i n i n g more l e a n meat and 9 l e s s f a t . In regard to h e r e d i t a r y d i f f e r e n c e s i n body fa t n e s s i t i s i n t e r e s t i n g to note the work of Alonso and Moren (1955) w i t h h e r e d i t a r y obese mice. They found that even when the obese mice l o s t weight on a r e s t r i c t e d d i e t t h e i r bodies contained a grea t -er p r o p o r t i o n of f a t than h e r e d i t a r y l e a n mice subjected to the same treatment. I t was concluded that obese mice metabolise t h e i r food i n a manner d i f f e r e n t from t h a t of l e a n mice such that more f a t i s deposited per u n i t of food eaten. Studying f i v e breeds of pigs Weniger (1955) k i l l e d some from each breed at b i r t h and at l i v e weights of 30 kgs., 40 kgs^ 106 kgs., and 136 kgs. Carcasses were analyzed f o r f a t , p r o t e i n , water and ash. The f i r s t breed d i f f e r e n c e s were demonstrated at 106 kgs. body weight. At t h i s and higher weights breeds d i f f e r e d as to a b i l i t y to deposit p r o t e i n and f a t i n the carcass. , Whiteman et a l (1951) and Warren and Dickerson (1952) found,.distinct d i f f e r e n c e s i n carcass q u a l i t y between breeds and between, l i n e s w i t h i n breeds. The former d i d not o b t a i n breed d i f f e r e n c e s however when considering b e l l y alone. Blackmore (1953) noted breed d i f f e r e n c e s i n percent l e a n cuts i n the c a r -cass. Fraser and S t o t h a r t (1947) found only small d i f f e r e n c e s i n carcass q u a l i t y between Yor k s h i r e s and Swedish Landrace t e s t e d at s e v e r a l Canadian s t a t i o n s . Large d i f f e r e n c e s have been demonstrated i n carcass q u a l i t y between sexes. Lacy (1932) found that g i l t s produced s i g n i f i - . ;. c a n t l y more ham and l o i n but about the same b e l l y and shoulder as the barrows. Barrows had a l a r g e r p r o p o r t i o n of t o t a l f a t 10 cuts and i n t e r n a l f a t . Male pigs were f a t t e r and had l e s s bone and muscle i n studies by McMeekan (1940). Miranda e_t a l (1946) found strong enough d i f f e r e n c e s i n r e s u l t s using 8 breeds of hogs to conclude t h a t , i n a l l o t t i n g to experiments where carcass q u a l i t y was to be measured, sexes should be considered. Hetzer et a l (1950) observed h i g h 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 y i e l d of f i v e l e a n cuts (ham, l o i n , bacon, p i c n i c and b u t t ) between barrows and g i l t s . G i l t s averaged 1,0% more l e a n cuts when these cuts were expressed as percentages of l i v e weight at slaughter a f t e r 24 hours o f f feed. In a study w i t h carcasses from B r i t i s h Large White p i g s Harrington and Pomeroy(1955) found t h a t sides from g i l t s were longer, t h i c k e r i n the b e l l y , t h i n n e r i n backfat and had b e t t e r developed eye muscles than those from barrows. Working w i t h Canadian Y o r k s h i r e s , Bennet and Coles (1946), Crampton and Ashton (1945 and 1946a), Fredeen (1953) and Fredeen and Lam-broughton (1956) a l l concluded that g i l t s produced l e a n e r c a r -casses than barrows. The r o l e of n u t r i t i o n i n determining carcass q u a l i t y was emphasized by the work of McMeekan (1940) and McMeekan and Hamm-ond (1940) i n studying the e f f e c t of low and h i g h planes of nut-r i t i o n on the development of the hog. These workers demonstrat-ed that pigs fed on a h i g h plane of n u t r i t i o n to 16 weeks and then on low plane gave higher percentages of l e a n than those fed on a low plane to 16 weeks and then on h i g h plane. They con-cluded that growth up to 16 weeks was mainly bone and muscle but a f t e r 16 weeks, mostly f a t . E a r l i e r work by E l l i s and 11 Z e l l e r (1934) had shown th a t pigs on 3/4 to | of a normal d i e t produced carcasses c o n t a i n i n g higher percentages of l e a n c u t s . Crampton and Ashton (1945) supported the r e s t r i c t i o n of food intake i n the l a t e p e r i o d to produce le a n e r carcasses. High f i b e r r a t i o n s can be u s e f u l i n producing l e a n e r c a r -casses. These r a t i o n s would e s s e n t i a l l y have the same e f f e c t as r e s t r i c t i n g feed intake since l e s s of the f i b r o u s r a t i o n would be digested. Axelsson and E r i k s s o n (1953) found a tendency to leaner carcasses as f i b e r l e v e l of the r a t i o n increased. Thinn-er backfat r e s u l t e d from high f i b e r r a t i o n s f e d i n work by Coey and Robinson (1955). Bohman et a l (1955) fed l e v e l s of a l f a l f a up to 50% of the r a t i o n and found that w i t h i n c r e a s i n g a l f a l f a l e v e l the depth of b a c k f a t , percentage of bacon b e l l y and f a t back i n the carcass decreased s i g n i f i c a n t l y w h i l e percentage ham, shoulder and l o i n increased s i g n i f i c a n t l y . However Teague and Hanson (1954) d i d not f i n d any s i g n i f i c a n t e f f e c t of h i g h f i b e r l e v e l s on carcass q u a l i t y when feeding p u r i f i e d d i e t s w i t h Ruffex as the f i b e r source. F a i l u r e to o b t a i n a s i g n i f i -cant d i f f e r e n c e could have been due to the small number of pigs used, however. The i n f l u e n c e of p r o t e i n l e v e l s on carcass q u a l i t y has been of some i n t e r e s t . In s t u d i e s w i t h p r o t e i n l e v e l s from 10% to 20% of the r a t i o n E l l i s and Hankins (1935), Ashton et a l (1955) and Stevenson e t a l (1955) a l l found that h i g h p r o t e i n l e v e l s produced leaner carcasses. High p r o t e i n l e v e l s increased per-cent l e a n cuts but reduced percent b e l l y i n work by Wilson et a l (1953). Catron et a l (1952) and Crampton and Ashton (1946a) 12 f a i l e d to o b t a i n any e f f e c t of varying p r o t e i n l e v e l s on carcass q u a l i t y . In the former work, however, the type of pig used was c o n s i s t e n t l y very f a t at slaughter and since the number of c a r -casses was small t h i s may have masked any d i f f e r e n c e s . In the l a t t e r the c r i t e r i o n of carcass q u a l i t y was perhaps not s u f f i c -i e n t l y accurate to demonstrate any d i f f e r e n c e s that may have been present. A low q u a l i t y p r o t e i n f e d at 12% i n the r a t i o n gave leaner carcasses than low q u a l i t y p r o t e i n at 16% or hi g h q u a l i t y p r o t -e i n at 12 or 16% i n work by Kropf et a l (1955). This was a r e s u l t of the very low r a t e of g a i n i n the pigs on the low q u a l i t y p r o t e i n at 12%. Carcass weights are r e l a t e d to fatness of the carcass. I t f o l l o w s from observations by McMeekan and Hammond (1940) and Hammond (1940 that heavier pigs w i l l tend to be f a t t e r . Coey and Robinson (1955) found that backfat thickness was s i g n i f i c -a n t l y p o s i t i v e l y c o r r e l a t e d w i t h carcass weight. E l l i s and Hankins (1937) obtained s i m i l a r c o r r e l a t i o n s . Season e f f e c t s can i n f l u e n c e carcass q u a l i t y . Crampton and Ashton (1946a) found that c o l d weather produced leaner carcasses. Winter pigs give leaner carcasses than summer pig s i n a study by Blackmore (1953). This leanness occurred d e s p i t e the f a c t that the winter pigs grew f a s t e r than the summer p i g s . Leaner carcasses were obtained by Perry e_t a l (1956) w i t h methyl testosterone f ed i n the d i e t of hogs and by Turman and Andrews (1955) w i t h i n j e c t i o n of p u r i f i e d a n t e r i o r p i t u i t a r y growth hormone. 13 B. Organs 1. D i g e s t i v e t r a c t Size and weight of stomach, small i n t e s t i n e and l a r g e i n -t e s t i n e are mainly a f f e c t e d by the nature of the d i e t s f e d . fficMeekan (1940) obtained heavier and l a r g e r i n t e s t i n a l t r a c t s from pigs on a high plane of n u t r i t i o n throughout t h e i r growing-and f a t t e n i n g p e r i o d . However, these pigs were also the ones de p o s i t i n g a l a r g e amount of f a t throughout the body so perhaps the heavy weights were due to f a t l a i d down i n the w a l l s of the i n t e s t i n e . Wussow and Weniger (1954) took weights of stomach, small i n t e s t i n e and l a r g e i n t e s t i n e i n pigs of three breeds on v a r i e d d i e t s . They found t h a t the weight of a l l three s e c t i o n s of the d i g e s t i v e t r a c t were increased by bulky d i e t s . No breed d i f f -erences i n d i g e s t i v e t r a c t s i z e were found. Horst (1954) ob-ta i n e d s i g n i f i c a n t l y heavier stomachs and small i n t e s t i n e s i n pigs r e c e i v i n g h i g h b a l l a s t r a t i o n s . Although t o t a l d i g e s t i v e t r a c t was s i g n i f i c a n t l y heavier the colon and caecum were not s i g n i f i c a n t l y heavier on the h i g h b a l l a s t feed. The l a t t e r worker a l s o measured l e n g t h and volume of the d i g e s t i v e t r a c t but found no s i g n i f i c a n t d i f f e r e n c e s between d i e t s . In work w i t h r a t s Wierda (1942) found that l a r g e i n t e s t i n e and caecum l e n g t h were d e f i n i t e l y increased by a bulky d i e t but the small i n t e s t i n e was not a f f e c t e d . In a l a t e r paper (Wierda, J950) t h i s worker found the small i n t e s t i n e to be he a v i e s t on a hi g h carbohydrate d i e t and l i g h t e s t on a balanced, concentrated d i e t w i t h these d i f f e r e n c e s 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 . 14 A h i g h - f a t and h i g h agar (bulky) d i e t gave intermediate weights f o r the small i n t e s t i n e . The l a r g e i n t e s t i n e was s i g n i f i c a n t l y heavier on the bulky d i e t t h i s being due both to a t h i c k e n i n g of the i n t e s t i n a l w a l l and an increase i n diameter. In t h i s paper Wierda r e p o r t s work by Wetzel i n which he observed t h a t r a t s on a pure meat d i e t had a heavier l a r g e i n t e s t i n e but a l i g h t e r small i n t e s t i n e than those on a l l p l a n t or mixed d i e t s . Wide weight d i f f e r e n c e s between animals however may have caiised t h i s to occur as no c o r r e c t i o n s were made f o r body weight. Bohman et a l (1955) found that weights of stomach and l a r g e i n t e s t i n e were increased as l e v e l of a l f a l f a f e d to hogs was increased. Small i n t e s t i n e however was not a f f e c t e d . These d i f f e r e n c e s were a t t r i b u t e d to longer periods of feed storage i n the stomach and l a r g e i n t e s t i n e than i n the small i n t e s t i n e where feed passed through q u i t e r a p i d l y . Workers have made some i n t e r e s t i n g observations on the a f f e c t of a n t i b i o t i c s on the d i g e s t i v e t r a c t . Coates e t a l (1955) obtained increased growth and decreased weight of the small i n t e s t i n e i n c h i c k s r e c e i v i n g procaine p e n i c i l l i n i n a normal mash. Upon r a i s i n g c h i c k s i n an i s o l a t e d , s t e r i l i z e d area however they d i d not o b t a i n a growth increase or a dec-rease i n i n t e s t i n e weight. These workers t h e o r i z e t h a t d i s -ease thickens the i n t e s t i n e w a l l r e s u l t i n g i n lessened absorp-t i o n of n u t r i e n t s and t h e r e f o r e they g.ot no e f f e c t under s t e r i l e c o n d i t i o n s . The degree of s t e r i l i t y could be questioned however as no b a c t e r i o l o g i c a l checks were made on e i t h e r the c h i c k s or t h e i r environment. Taylor and Harrington (1955) r e p o r t work 15 by Gordon w i t h c h i c k s i n whicfi d i e t a r y supplements of both procaine p e n i c i l l i n and terramycin s i g n i f i c a n t l y reduced the weight of the small i n t e s t i n e . Taylor and Harri n g t o n (1955) r an t e s t s w i t h Large White pigs and found that weights of stomach, caecum and l a r g e i n t e s -t i n e were not s i g n i f i c a n t l y a f f e c t e d by e i t h e r aureomycin or p e n i c i l l i n i n the d i e t . The small i n t e s t i n e was s i g n i f i c a n t l y l i g h t e r i n the p e n i c i l l i n - f e d l o t s . Braude et a l (1955) found a.itehdency to reduced i n t e s t i n a l t r a c t weight i n pigs r e c e i v i n g aureomycin i n t h e i r d i e t . Length was not a f f e c t e d , however, i n d i c a t i n g a p o s s i b l e t h i n n i n g of the i n t e s t i n a l w a l l i n t r e a t -ed groups. Bohman et a l (1955) could f i n d no i n f l u e n c e of aureomycin 6n e i t h e r l a r g e i n t e s t i n e , small i n t e s t i n e or stomach weights i n p i g s . K h a l i l o v (1955) s t u d i e d the l e n g t h and character of the i n t e s t i n e i n c a r n i v o r e s , i n s e c t i v o r e s , and h e r b i v o r e s . He concluded t h a t i n hoofed animals the absorptive surface of the i n t e s t i n e was increased by an increase i n l e n g t h r a t h e r than any change i n t h e - v i l l i themselves. The i n t e r e s t i n g o b s e r vation was made by Coates et a l (1955) i n t h e i r work w i t h chicks t h a t the weight of the small i n t e s t i n e increased when l i v e r was added to the d i e t . 2. Heart Heart s i z e i s c l o s e l y r e l a t e d to body s i z e and a c t i v i t y of the animal. Work by Walter and Addis (1939) demonstrated th a t any f a c t o r which changes the r a t e of volume f l o w of blood 16 changes the amount of work performed by .the h e a r t . They found that decreasing metabolic r a t e i n r a t s by thyroidectomy r e s u l t e d i n decreased heart weight. A d m i n i s t r a t i o n of t h y r o x i n , on the other hand, increased heart weight. They concluded t h a t weight changes i n heart r e s u l t d i r e c t l y from the amount of work done by the heart. McMeekan (1940) w i t h hogs on v a r i o u s planes of n u t r i t i o n found t h a t those on the low plane from weaning to slaughter had higher heart to body r a t i o s than those on other planes. This d i f f e r e n c e was a t t r i b u t e d to the greater a c t i v i t y of the p i g s on the IOY/ r a t i o n due to t h e i r searching f o r more food. Work by Joseph (1908) w i t h dogs, cats r a b b i t s and guinea-pigs showed d i f f e r e n c e s i n heart s i z e between animal species i n that the more a c t i v e species had l a r g e r heart. This worker a l s o r e p o r t s a study by Kulbs i n which a dog kept i n a cage had a smaller heart than a dog of the same body weight e x e r c i s e d r e g u l a r l y on a t r e a d m i l l . Brody and K i b l e r (1941) and Quiring (1946) support the above f i n d i n g t h a t more a c t i v e species have l a r g e r h e a r t s . The former a l s o showed th a t heart weight tends to increase w i t h body weight and d e r i v e d formulae to p r e d i c t organ weights from body weights. Addis and Gray (1950) found that the formula l o g Y = log a + l o g b l o g x was s u t i a b l e f o r p r e d i c t i n g organ weight from : body weight. Latimer (1947) obtained a high c o r r e l a t i o n of .85 between heart and body weight. Wilcox et a l (1955) obtained heavier hearts from animals fed sucrose before slaughter. 17 3. L i v e r The l i v e r appears to he a f f e c t e d by a greater v a r i e t y of conditions than the heart. A c t i v i t y tends to increase l i v e r weight j u s t as i t does heart weight. In t h i s respect Walter and Addis (1939) found that l i v e r weight p a r a l l e l e d heart weight i n t h e i r study of metabolic r a t e s . They concluded that l i v e r weight changes w i t h the amount of work done by the l i v e r . McMeekan (1940) obtained heavier l i v e r s i n those pigs on h i g h r a t i o n s from weaning to s l a u g h t e r . This could i n d i c a t e g r e a t e r l i v e r a c t i v i t y due to heavier feed consumption or e l s e greater stores of glycogen and f a t i n the l i v e r t i s s u e . Webster et a l (1947) found that r a t i o s of l i v e r to body weight tended to decrease w i t h i n c r e a s i n g body weight. Dick (1956) obtained s i m i l a r r e s u l t s w i t h sheep foetuses. He found that the r a t i o of true hepatic t i s s u e weight to foetus weight decreased as the foetus developed i n d i c a t i n g a p o s s i b l e decrease i n l i v e r a c t i v i t y as the s p e c i f i c growth r a t e decreased or e l s e and increase i n f u n c t i o n a l c a p a c i t y of the i n d i v i d u a l c e l l s . L i v e r weight can be i n f l u e n c e d by pre-slaughter treatment. Madsen ( c i t e d by Gibbons and Rose, 1950), Gibbons and Rose (1950) and Wilcox et a l (1953) a l l obtained heavier l i v e r s by feeding sucrose to pigs before slaughter. Gibbons and Rose found t h i s increase to r e s u l t mainly from greater glycogen storage i n the l i v e r s . Further evidence of the r e l a t i o n s h i p of l i v e r s i z e to . p h y s i o l o g i c a l a c t i v i t y i s given i n work by Bland ejb'al (195S) and H a r r i s et a l (1953). In both cases a d m i n i s t r a t i o n of ACTH 18 or c o r t i s o n e r e s u l t e d i n l a r g e increases i n l i v e r weight w i t h young guinea p i g s . In the l a t t e r study the increase i n l i v e r weight was a s s o c i a t e d w i t h increased glycogen, water and p r o t e i n l e v e l s i n the l i v e r s . These workers noted a l s o t h a t response to ACTH v a r i e d between species w i t h r a b b i t s showing s i m i l a r r e s u l t s to guinea pigs but y.oung r a t s , c hicks or mice showing no change i n l i v e r weight. In a s i m i l a r study Cherry e t a l (1954) r e c -eived a gr e a t e r increase i n l i v e r weight from c o r t i s o n e than from ACTH. I t was t h e o r i z e d that more c o r t i s o n e was introduced i n t o the c i r c u l a t o r y system by d i r e c t i n j e c t i o n than was produc-ed through s t i m u l a t i o n of the adrenals by ACTH. Wo c o n s i s t e n t sex e f f e c t on l i v e r s i z e has been noted. Webster et a l (1947) noted a tendency to heavier l i v e r s i n male l a b o r a t o r y animals. C r i l e and Quiring (1940) noted s l i g h t l y h eavier average l i v e r weights f o r female p i g s . C e r t a i n other c o n d i t i o n s have been demonstrated to influence l i v e r weight. Kropf e t a l (1955) found t h a t l i v e r weight tended to increase as p r o t e i n l e v e l i n the r a t i o n increased. .Total body roentgen i r r a d i a t i o n produced smaller l i v e r s i n work by Azarnoff and Roofe (1951). Barron and Litman ( c i t e d by Ahronheim, 1937) noted e n l a r g -ed l i v e r s i n c e r t a i n disease c o n d i t i o n s of both chronic and acute nature. Blackmore (1953) found l a r g e r l i v e r s i n pigs f e d in. the winter months than i n those f e d i n the summer. He speculates that this'-'may have r e s u l t e d from greater use of feed i n the cool e r weather to maintain the p i g s ' body temperature. Feed 19 records were not a v a i l a b l e however to prove t h i s p o i n t . Taylor and Harrington (1955) observed a l a r g e increase i n l i v e r s i z e i n pigs f e d on a p e n i c i l l i n - s u p p l e m e n t e d r a t i o n . 4. Spleen The spleen i s c l o s e l y a s s o c i a t e d w i t h the use of red blood c e l l s i n the animal body. I t s s i z e i n general i s a f f e c t e d by co n d i t i o n s which a l t e r . t h e r a t e of blood use i n the body. Bar-c r o f t e_t a l (1925) demonstrated that the spleen could act as a r e s e r v o i r f o r red blood corpuscles and that spleen s i z e was decreased by haemorrhage. Method of sl a u g h t e r i n g a l s o i n f l u e n -ced spleen weight i n t h i s study. They conjectured t h a t the spleen would tend to be contracted by e x e r c i s e since i t used red blood c e l l s . Support to t h i s i s given i n l a t e r work by B a r c r o f t and Stevens (1927) i n which e x e r c i s e upon a t r e a d m i l l r e s u l t e d i n a l o s s of spleen weight. Further evidence of the spleen's r o l e i n blood use i n the body i s given by the work of Hargis and Mann (1925) and B a r c r o f t and Stevens (1928). The former found that g a s t r o - i n t e s t i n a l a c t i v i t y a f f e c t e d spleen volume; the l a t t e r t h a t estrous and pregnancy produced spleen shrinkage. A l l of these c o n d i t i o n s tend to increase movement of blood to c e r t a i n regions of the body, thus blood stored i n the spleen would be drawn out f o r use. Spleen s i z e i s i n f l u e n c e d by environmental c o n d i t i o n s a l s o . Hargis and Mann (1925) observed that the spleen responded to e x t e r n a l s t i m u l i by a r e d u c t i o n i n volume. Ahronheim (1937)' found that spleen s i z e was a l t e r e d by va r i o u s disease conditions 20 of both a chronic and acute nature. Azarnoff and Roofe (1951) observed a 40% r e d u c t i o n i n spleen s i z e of r a t s subjected to complete i r r a d i a t i o n . Taylor and H a r r i n g t o n (1955) r e p o r t a s i g n i f i c a n t r e d u c t i o n i n spleen weight w i t h aureomycin-supplemented swine r a t i o n s . Other workers (Bohman et a l , 1955: Braude e_t a l , 1955), however, f a i l e d to f i n d any e f f e c t of aureomycin on spleen weights. Webster et a l (1947) found t h a t the r a t i o of spleen to body weight tended to decrease w i t h i n c r e a s i n g body weight. Latimer (1947) obtained a p o s i t i v e c o r r e l a t i o n of .65 between spleen weight and body weight. 5. Adrenals The adrenals are i n t i m a t e l y r e l a t e d to the p h y s i o l o g i c a l a c t i v i t i e s w i t h i n the animal body. They are s t i m u l a t e d by the a d r e n o c o r t i c o t r o p i c hormone r e l e a s e d from the a n t e r i o r lobe of the p i t u i t a r y . In t u r n they r e l e a s e a d r e n a l i n and c o r t i n which are both important to body f u n c t i o n . Ingle and K e n d a l l (1937) found that a d m i n i s t r a t i o n of c o r t i n to r a t s r e s u l t e d i n decreas-ed adrenal s i z e . They concluded that when s u f f i c i e n t c o r t i n i s present i n the body f l u i d s f o r a l l p h y s i o l o g i c requirements the output of adrenotropic s e c r e t i o n s from the p i t u i t a r y i s supp-ressed. This f i n d i n g was confirmed by work of Ingle and Mason (1938), H a r r i s et a l (1955) and Constable e t a l (1956) who a l l obtained reduced adrenal s i z e on a d m i n i s t r a t i o n of c o r t i n com-pounds. The l a t t e r two papers a l s o reported a d m i n i s t r a t i o n of ACTH ( a d r e n o c o r t i c o t r o p i c hormone) to r a t s . The produced an increase i n adrenal weight which was a t t r i b u t e d to an 21 increase i n adrenal a c t i v i t y r e s u l t i n g from ACTH s t i m u l a t i o n . S t r e s s c o n d i t i o n s are recognized as important i n f l u e n c e s on adrenal a c t i v i t y . Azarnoff and Roofe (1951) found enlarged adrenals i n r a t s exposed to i r r a d i a t i o n . Hurley and MacKenzie (1954) obtained adrenal enlargement i n r a t s under the s t r e s s c o n d i t i o n s of f a s t i n g , pantothenic a c i d d e f i c i e n c y and lowered oxygen t e n s i o n . Other s t r e s s f a c t o r s causing adrenal hypertrophy i n c l u d e ; s k i n denudation (Dum et a l , 1955), d e n s i t y of populat-i o n ( C h r i s t i a n , 1955), low temperatures ( N i c h o l l s and R o s s i t e r , 1955), r e s t r i c t e d feed intake (Campos Zamorano, 1955) and r e s t - ' r i c t e d s a l t i ntake (Goldman et a l , 1956). Animals used i n these stud i e s i ncluded r a t s , mice and r a b b i t s . Adrenal weights apparently d i f f e r between sexes, at l e a s t i n some animal species. Eaton (1958) found t h a t ddrenals were heavier i n male guinea p i g s . C h r i s t i a n (1953) stud i e d adrenal weights i n 25 species and observed that those of the mature female were heavier than the mature male i n a l l species except the r a b b i t . He a l s o found that adrenal gland weight f o l l o w e d a d e f i n i t e l o g a r i t h m i c r e l a t i o n s h i p f o r a l l species examined. Dunn et a l (1955) noted heavier adrenals i n female r a t s . Working w i t h inbred and crossbred guinea pigs Eaton (1938) found d i f f e r e n c e s i n adrenal weights between breeds. Mason ( c i t e d by Dumm et a l , 1955) has suggested t h a t a s p e c i f i c adrenal weight maintaining f a c t o r may be secreted by the a n t e r i o r p i t u i t a r y . Most ?/orkers however a t t r i b u t e adrenal hypertrophy to an increased output of a d r e n o c o r t i c o t r o p i c hor-mone from the p i t u i t a r y . 22 Recent t e s t s have shown that adrenal weight i s increased when s t i l h e s t r o l i s administered. Clegg and Cole (1954) and C a h i l l et a l (1956) observed t h i s w i t h c a t t l e and Hartsook and Magruder (1956) w i t h r a t s . Dickson et a l (1954) found an i n d i c a t i o n of adrenal weight increase i n r a t s r e c e i v i n g terramycin or f i s h s o l u b l e s i n t h e i r r a t i o n . I n j e c t i o n of testosterone propionate i n mice decreased adrenal s i z e i n t e s t s by Homburger and P e t t e n g i l l (1955). C. R e l a t i o n s h i p s L Between economic c h a r a c t e r i s t i c s Rate of g a i n and feed requirements per u n i t g a i n are c l o s e l y r e l a t e d . Evvard et a l (1927) found a strong c o r r e l a t i o n of -.59 between d a i l y g a i n and feed requirements i n data from the Iowa State College herd. Other workers who support t h i s r e l a t i o n s h i p i n c l u d e Lush (1936), S t o t h a r t (1938), Z e l l e r (1944), Dickerson (1947) and Warren and Dickerson (1952). Fredeen (1953) found a strong c o r r e l a t i o n of .51 between feed per 100 l b s . of carcass g a i n and age at slaughter. He a t t r i b u t e s t h i s to the l a r g e r maintenance requirement f o r the slower growing p i g . A n a l y s i s of data by Weniger (1955) i n which carcaases were t e s t e d f o r f a t and p r o t e i n d e p o s i t i o n at v a r i o u s weights showed that pigs gaining at the r a t e of 600 to 700 grams per day gave higher p r o t e i n d e p o s i t i o n than pigs gaining at higher r a t e s . As d a i l y g a i n increased over 700 grams f a t d e p o s i t i o n a l s o i n c r e a s -ed. This r e l a t i o n s h i p of f a s t g a i n and carcass fatness was a l s o demonstrated i n e a r l i e r papers by Donald (1940), Bennet and Coles 23 (1946), Blunn and Baker (1947) and Dickerson (1947). Contrary to the above f i n d i n g s , Winters e_t a l (1949) demonstrated a p o s i t -i v e r e l a t i o n s h i p between r a t e of g a i n and leanness i n data where c o r r e c t i o n s had been made f o r maintenance allowances. Methods of c o r r e c t i o n are not c l e a r l y o u t l i n e d i n t h i s paper however. In a l a t e r study Cummings and Winters (1951) co r r e c t e d data f o r slaughter weight and breed d i f f e r e n c e s and obtained a p o s i t i v e c o r r e l a t i o n between age at 200 l b s . and y i e l d of f i v e p r i m a l carcass cuts. This was i n t e r p r e t e d as i n d i c a t i n g a p o s i t i v e r e l a t i o n s h i p between growth r a t e and l e a n i n the carcass. The i n c l u s i o n of b e l l y i n the p r i m a l cuts may have confused the r e l -a t i o n s h i p however. B e l l y would appear to be a f f e c t e d more by f a t than by l e a n i n the carcass. Blunn and Baker (1947) suggest the p o s s i b i l i t y of breed d i f f e r e n c e s i n the r e l a t i o n between fatness and r a t e of g a i n . They found l e s s genetic but more environmental a s s o c i a t i o n b e t -ween r a p i d g a i n and fatness i n Duroc-Jerseys than had been found i n other work w i t h Poland Chinas. Winters et, a l (1949) and Blackmore (1953) a l s o put forward the p o s s i b i l i t y of breed d i f f - , erences i n t h e i r data considering the above r e l a t i o n s h i p . A strong p o s i t i v e c o r r e l a t i o n between slaughter weight of the hog and f a t on the carcass i s evident from work by S t o t h a r t (1938), Hazel et a l (1943) and Willman and K r i d e r (1943). I t i s i n t e r e s t i n g to note the work of Donald (1940) where the r e l a t i o n s h i p between d a i l y g a i n and fatness was stronger f o r one group w i t h f a t measured over the l o i n w h i l e i n another i t was stronger f o r f a t measured over the rump. 24 In data from Danish t e s t s t a t i o n s Lush (1936) found a pos- . i t i v e r e l a t i o n s h i p between dressing percent and f a t i n the c a r -cass. Aunan and Winters (1949) obtained a c o r r e l a t i o n of .66 between dressing percent and percent f a t i n the carcass. This c o r r e l a t i o n i s h i g h l y s i g n i f i c a n t . A p o s i t i v e r e l a t i o n s h i p was also.found by Blackmore (1953). 2. Between economic c h a r a c t e r i s t i c s and organs Schmidt and Vogel ( c i t e d by Blackmore, 1953) presented c o r r e l a t i o n s between heart s i z e and days from 30 to 100 kgs. i n pi g s j and between heart s i z e and f a t / l e a n r a t i o s . Both c o r r e l -a t i o n s were negative and q u i t e low. K r a y b i l l et a l (1954) ob-ta i n e d the f o l l o w i n g range of c o r r e l a t i o n s w i t h data from v a r -ious groups of beef c a t t l e ; L i v e r and l e a n body mass from .17 to .98 heart and l e a n body mass from .12 to .97 spleen and l e a n body mass from .41 to .95 These c o r r e l a t i o n s are g e n e r a l l y h i g h . However, no mention i s made of p o s s i b l e treatment e f f e c t s t h a t may be present since the data were taken from a number of research s t a t i o n s . Blackmore (1953) found a negative r e g r e s s i o n of g a i n on spleen weight, p o s i t i v e r e g r e s s i o n s of l e a n cuts on l i v e r , heart and spleen and negative r e g r e s s i o n s of f a t cuts on l i v e r , heart and spleen w i t h i n breed c l a s s e s of hogs. These reg r e s s i o n s were non-s i g n i f i c a n t . 3. Between organs Ahronheim (1937) observed a p o s s i b l e p o s i t i v e r e l a t i o n s h i p between l i v e r and spleen s i z e . He found that under many disease 25 c o n d i t i o n s spleen and l i v e r were a f f e c t e d s i m i l a r l y . Latimer (1947) obtained a l l p o s i t i v e c o r r e l a t i o n s when con-s i d e r i n g various organs i n the c a t . Table 2 gives the c o r r e l a t -ions found by t h i s worker. Table 2 C o r r e l a t i o n s Between Organs i n the Cat Organs Males Females Heart and spleen .65 .56 Heart and d i g e s t i v e tube wt. .68 .56 Heart and l i v e r .78 .62 Spleen and d i g . tube wt. .45 .07 Spleen and l i v e r .37 .19 Dig. tub® wt. and l i v e r .65 .67 Grahn ( c i t e d by Blackmore, 1953) found only 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 s between v a r i o u s organs i n mice. C o r r e l a t i o n s were negative f o r heart and spleen and f o r heart and l i v e r , but posit-iv e f o r l i v e r and spleen. Blackmore (1953) obtained n o n - s i g n i f i c a n t p o s i t i v e c o r r e l -a t i o n s between l i v e r and heart and between l i v e r and spleen i n p i g s . A s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n was obtained between heart and spleen i n one group of pigs used i n t h i s study while the same c o r r e l a t i o n was p o s i t i v e but n o n - s i g n i f i c a n t i n other groups. 26 I I . MATERIALS AND METHODS Data used i n t h i s study were taken from three experiments conducted at the Experimental Farm, Agass i z , B.C. These e x p e r i -ments were planned p r i m a r i l y to t e s t treatment d i f f e r e n c e s , but the data c o l l e c t e d were a l s o considered s u i t a b l e to gi v e i n f o r -mation on the r e l a t i o n s h i p s i n c l u d e d i n t h i s study. Large d i f -ferences between experiments n e c e s s i t a t e d separate a n a l y s i s of the data from each experiment. Pigs from the three experiments w i l l be denoted Group A (48 p i g s ) , Group B (24 pigs) and Group C (60 p i g s ) . A. Animals Pigs used i n a l l three groups were purebred Y o r k s h i r e s bred and r a i s e d at the Experimental Farm, Agass i z , B.C. A l l pi g s i n Groups A and B, were s i r e d by one boar. Those i n Group C were a l l s i r e d by a second boar. Both female and c a s t r a t e male pigs were used i n Groups A and C. Since l i m i t e d numbers prevented balancing the sexes, pigs i n these groups were a l l o t t e d at random to treatments, r e -gardless of sex. Data from these groups were c o r r e c t e d f o r sex d i f f e r e n c e s p r i o r to s t a t i s t i c a l a n a l y s i s . P i g s i n Group B were a l l c a s t r a t e d males and were a l l o t t e d at random to treatments. B. Treatments 1. Group A (summer 1955) These pigs were used to t e s t forage u t i l i z a t i o n and r a t i o n balancing by s e l f - s e l e c t i o n of g r a i n mix and p r o t e i n supplement. 27 Treatments and numbers of pigs used were as f o l l o w s : 1. On pasture (2 r e p l i c a t e s ) (a) G r a i n mix and p r o t e i n supplement i n separate s e l f - f e e d e r s (4 pigs per r e p l i c a t e ) (b) Complete r a t i o n (4 pigs per r e p l i c a t e ) 2. In d r y l o t w i t h f r e s h cut forage (2 r e p l i c a t e s ) (a) G r a i n mix and p r o t e i n supplement separate (4 pigs per r e p l i c a t e ) (b) Complete r a t i o n (4 pigs per r e p l i c a t e ) 3. In d r y l o t without forage (2 r e p l i c a t e s ) (a) G r a i n mix and p r o t e i n supplement, separate (4 pigs per r e p l i c a t e ) (b) Complete r a t i o n (4 pigs per r e p l i c a t e ) A pasture area seeded to orchard grass and l a d i n o c l o v e r was d i v i d e d i n t o 32 p l o t s of one-twentieth acre each. S i x t e e n p l o t s made up a r e p l i c a t e . W i t h i n each r e p l i c a t e the p l o t s were d i v i d e d i n t o groups of f o u r , each group being a l l o t t e d at r a n -dom to a pasture or cut forage treatment. Thus each p i g r e c e i v -ing cut forage i n d r y l o t was a l l o t t e d a p l o t i n the same manner as those pigs a c t u a l l y fed on pasture and r e c e i v e d only forage cut from t h i s p l o t . Table 3 g i v e s i n g r e d i e n t s of r a t i o n s used. 28 TABLE 3. R a t i o n Ingredients Used i n Forage U t i l i z a t i o n T r i a l Balanced R a t i o n P e r i o d 1 P e r i o d 2 G r a i n P r o t e i n (90-110 l b s . ) (110-200 l b s . ) mix supplement l b s . l b s . l b s . l b s . Barley- 60.2 65.8 70 -Oats 25.8 28.2 30 -Meat scrap 4.2 ; 1.8 - 30 Soyameal 4.9 2.1 - 35 Linseed Oilmeal 2.8 1.2 - 20 Dehydrated grass 2.1 0.9 - 15 S a l t 0.5 0.5 0.5 0.5 Limestone 0.5 0.5 0.5 0.5 2. Group B (winter 1955-56) These pigs were used to t e s t the u t i l i z a t i o n of d r i e d apple pomace i n the swine r a t i o n . Treatments and numbers of pigs used were as f o l l o w s : 1. Balanced r a t i o n without d r i e d apple pomace (2 r e p l i c a t e s , 3 pigs per r e p l i c a t e ) 2. R a t i o n c o n t a i n i n g 10% d r i e d pomace (2 r e p l i c a t e s , 3 pigs per r e p l i c a t e ) 3. Ration c o n t a i n i n g 20% d r i e d pomace (2 r e p l i c a t e s , 3 p i g s per r e p l i c a t e ) 29 4. R a t i o n c o n t a i n i n g 30% d r i e d pomace (2 r e p l i c a t e s , 3 pigs per r e p l i c a t e ) A l l r a t i o n s were "balanced to the same p r o t e i n and crude f i b e r l e v e l . A l l pigs were fed i n d r y l o t . Table 4 gives i n g r e d i e n t s of r a t i o n s used. TABLE 4 R a t i o n Ingredients i n Test of Dried Pomace U t i l i z a t i o n P e r i o d Growing (50-110 l b s . ) Fattening (110-200 l b s . ) l b s . l b s . l b s . l b s . l b s . l b s . l b s . l b s . Apple pomace — 10 20 30 - 10 20 30 Barley- 54 51 50 50 60 58 55 55 Oats 30 20 10 - 29 20 10 -Meat scrap 8 9 10 10 4 5 7 7 Soyameal 5 7 7 7 4 4 5 5 Linseed o i l meal 2 2 2 2 2 2 2 2 S a l t .5 .5 .5 .5 .5 .5 .5 .5 Limestone .5 .5 .5 .5 .5 .5 .5 .5 3. Group C (summer (1956) These pigs were used to t e s t d r i e d apple pomace u t i l i z a t i o n at two l e v e l s of p r o t e i n . Treatments and numbers of p i g s used were as f o l l o w s : 1. Ration without d r i e d apple pomace (2 r e p l i c a t e s ) (a) Standard p r o t e i n - 15% crude p r o t e i n 30 from 50 to 110 l b s . ; 13% from 110 to slaughter (5 pigs per r e p l i c a t e ) (b) High p r o t e i n - 18% crude p r o t e i n from 50 to 110 l b s . ; 15% from 110 to slaughter (5 p i g s per r e p l i c a t e ) 2. R a t i o n containing 20% d r i e d pomace (2 r e p l i c a t e s ) (a) as above (b) as above 3. R a t i o n con t a i n i n g 40% d r i e d pomace (2 r e p l i c a t e s ) (a) as above (b) as above Rations were balanced to crude f i b e r l e v e l s considered reasonable f o r feeder p i g s . A l l pigs were f e d i n d r y l o t . Table 5 g i v e s i n g r e d i e n t s of r a t i o n s used. C. Feed and Body Weight Records Pigs i n the three groups were a l l i n d i v i d u a l l y s e l f f e d . In Group A, however, the wooden s e l f - f e e d e r s used were pe n e t r a t -ed by moisture due to the very wet season. I t wan f e l t t h a t the feed records on t h i s group were inaccurate so they have been e l i m i n a t e d from t h i s study. P i g s - i n Group A were put on t e s t r a t i o n s at body weights of approximately 90 l b s . In Groups B and C pigs were put on at approximately 50 l b s . Pigs were taken o f f t e s t f o r slaughter at a l i v e ?/eight which would give a shrunk weight i n the range 190 to 210 l b s . Shrunk weights were taken a f t e r 21 hours o f f feed and water. 31 TABLE 5 Ration Ingredients i n T e s t i n g E f f e c t of P r o t e i n Levels on Dried Apple Pomace U t i l i z a t i o n Pomace 0% 20% 40%' P r o t e i n Standard High* Standard High* Standard High* Weight 50 :110 -110 ^200 50 -110 50 -110 -110 -200 50 -110 50 110 -110 -200 50 -110 l b . l b . l b . l b . l b . l b . l b . l b . l b . Apple pomace — — — 20 20 20 40 40 40 B a r l e y 55 60 50 52 55 40 39 44 31 Oats 30 30 27 10 12 14 _ - -Meat scrap 8 4 12 9 7 16 12 9 18 Soya-meal 6 5 10 8 5 9 8 6 10 S a l t .5 5 .5 .5 • 5 .5 .5 5 .5 Lime-stone .5 5 .5 .5 • 5 .5 .5 5 .5 A High p r o t e i n 110-200 same as Standard P r o t e i n 50-110. 32 D. Slaughtering and Organ Weights Pigs i n a l l groups were taken by truck from Agassiz to the slaughterhouse of Clappison Packers L t d . at Haney, B.C. f o r sl a u g h t e r i n g . The same sl a u g h t e r i n g procedure was used f o r a l l p i g s . The i n t a c t d i g e s t i v e t r a c t of each p i g w i t h the spleen attached was dropped from the carcass i n t o a p a i l marked w i t h that pig's number. The heart and l i v e r were removed, cleaned of extraneous t i s s u e ( i n c l u d i n g the b i l e duct) and weighed to the nearest gram. In Group C the adrenal glands were removed from each p i g and placed i n marked p l a s t i c c o n t a i n e r s . The i n t a c t d i g e s t i v e t r a c t s , spleens and adrenal glands were returned to Agassiz. The d i g e s t i v e t r a c t wqs f r e e d of f a t , pancreatic t i s s u e and other extraneous t i s s u e and emptied of a l l contents. The duodenum was cut from the stomach and the small i n t e s t i n e from the caecum. The stomach, small i n t e s t i n e and la r g e i n t e s t i n e ( i n c l u d i n g caecum and rectum) were weighed separately to the nearest gram. The spleen and adrenals were f r e e d of f a t and weighed to the nearest gram and 10 m i l l i g r a m s r e s p e c t i v e l y . E. Carcass Cutting and Weighing Hot carcass weight was taken immediately a f t e r e v i s c e r a t -i n g . Carcasses were s p l i t down the back and weighed w i t h k i d -neys and l e a f - f a t i n j head and f e e t on. Cold carcass weights were taken a f t e r c h i l l i n g f o r approximately 84 hours. Carcasses were cut i n t o r e g u l a r commercial cuts by exper-ienced c u t t e r s . Weights to the nearest one-quarter pound were 35 recorded f o r f e e t , head, l e a f - f a t , kidneys, shoulder, l o i n , ham, and b e l l y . Both rough and trimmed weights of the shoulder, l o i n ham and b e l l y were taken. E . Treatment of Data Since carcass weights v a r i e d , the use of absolute measures of organs and carcass cuts would have introduced a b i a s . There-f o r e the values f o r organs and carcass measures were c a l c u l a t e d i n percentages as f o l l o w s : 1. Lean cuts - the sum of shoulder, l o i n and ham a f t e r trimming as a percentage of the c o l d carcass weight minus head, f e e t and kidneys. 2. Fat c u t s - l e a f - f a t plus the f a t t r i m from the shouHer, l o i n , ham and b e l l y as a percentage of the c o l d carcass minus head, f e e t and kidneys. 3. B e l l y . - trimmed b e l l y as a percentage of the c o l d c a r -cass minus head, f e e t and kidneys. 4. Organs - each as a percentage of the hot carcass weight (adrenals x 100). 5. D i g e s t i v e t r a c t - each s e c t i o n as a percentage of the hot carcass weight. Dressing percentage was the hot carcass as a percentage of the shrunk l i v e weight. D a i l y g a i n was c a l c u l a t e d as the d i f f -erence between l i v e weight on t e s t and shrunk l i v e weight o f f t e s t d i v i d e d by the t o t a l number of days on t e s t . Feed e f f i c i e n c y was c a l c u l a t e d both on the b a s i s of feed r e q u i r e d per 100 l b s . of t o t a l body g a i n and feed per 100 l b s . carcass gain. T o t a l body g a i n i s the d i f f e r e n c e between shrunk 34 l i v e weight o f f t e s t and weight at s t a r t of t e s t . Carcass g a i n i s the d i f f e r e n c e between hot carcass weight and l i v e weight at s t a r t of t e s t x .65. The f a c t o r .65 i s based on the assumption th a t the p i g at 50 l b s . l i v e weight would have a dressing percentage of 65. This f i g u r e has been adopted by the Canadian Advanced R e g i s t r y Board f o r use i n c a l c u l a t i n g carcass g a i n on t e s t p i g s . The three experimental groups were t r e a t e d s e p a r a t e l y f o r s t a t i s t i c a l a n a l y s i s since l a r g e between-group d i f f e r e n c e s were apparent. P r e l i m i n a r y a n a l y s i s showed sex d i f f e r e n c e s i n Groups A and C. Before f u r t h e r a n a l y s i s c o r r e c t i o n s were made i n these two groups. In both cases female values were c o r r e c t e d to the male a'verage. Corrected data were t e s t e d f o r treatment d i f f e r e n c e s w i t h -i n groups by r e g u l a r a n a l y s i s of variance procedures. Regress-ions and c o r r e l a t i o n s between treatments as w e l l as w i t h i n treatments were c a l c u l a t e d i n each group. 35 I I I . RESULTS Resu l t s are presented i n t a b u l a r form at the end of t h i s s e c t i o n . Means of economic c h a r a c t e r i s t i c s i n a l l groups are presented i n Table 6. Means of organs i n a l l groups are presen-ted i n Table 7. A. A n a l y s i s of Variance 1. Group A Sex d i f f e r e n c e s were determined by p r e l i m i n a r y a n a l y s i s and a l l data c o r r e c t e d before treatment d i f f e r e n c e s were considered. There are s i g n i f i c a n t sex d i f f e r e n c e s f o r d a i l y g a i n , dressing percent, percent l e a n c u t s , percent f a t c u t s , percent b e l l y , and spleen. Mean squares from the a n a l y s i s of variance f o r treatment d i f f e r e n c e s are presented i n Tables 8 and 9. There were no s i g -n i f i c a n t d i f f e r e n c e s between the complete r a t i o n and the s e l f -s e l e c t e d r a t i o n . S i g n i f i c a n t d i f f e r e n c e s between forage feeding treatments were found f o r d a i l y g a i n , percent l e a n c u t s , percent f a t c u t s , percent b e l l y , heart spleen and stomach. A l l s i g n i f i -cant d i f f e r e n c e s were between the pasture-fed group and the two d r y l o t groups. No s i g n i f i c a n t d i f f e r e n c e s occurred between the cut forage and no forage treatments. 2. Group B A l l pigs i n t h i s group were males thus no sex c o r r e c t i o n was r e q u i r e d . Mean squares from the a n a l y s i s of variance f o r treatment d i f f e r e n c e s are presented i n Tables 10 and 11. Percent b e l l y 36 showed the only s i g n i f i c a n t d i f f e r e n c e between d r i e d apple pom-ace l e v e l s . 3. Group C Sex d i f f e r e n c e s were determined by p r e l i m i n a r y a n a l y s i s and a l l data c o r r e c t e d before treatment d i f f e r e n c e s were considered. There were s i g n i f i c a n t sex d i f f e r e n c e s f o r d a i l y g a i n , percent l e a n c u t s , percent f a t c u t s , percent b e l l y , heart and spleen. Mean squares from the a n a l y s i s of variance f o r treatment d i f f e r e n c e s are presented i n Tables 12 and 13. There were no s i g n i f i c a n t d i f f e r e n c e s between the two p r o t e i n l e v e l s . S i g n i f -i c a n t d i f f e r e n c e s between pomace l e v e l s occurred f o r d a i l y g a i n , dressing percent, percent l e a n c u t s , percent f a t c u t s , l i v e r , stomach, and l a r g e i n t e s t i n e . S i g n i f i c a n t d i f f e r e n c e s were mainly between the 40% pomace l e v e l , and the other two l e v e l s used. The only s i g n i f i c a n t d i f f e r e n c e between 0% pomace and 20% pomace was f o r stomach. B. A n a l y s i s of Covariance 1. C o r r e l a t i o n s Simple c o r r e l a t i o n s between economic c h a r a c t e r i s t i c s , b e t -ween economic c h a r a c t e r i s t i c s and organ weights and between organ weights were c a l c u l a t e d i n each group. W i t h i n treatment c o r r e l a t i o n s are presented i n Table 14 and between treatment c o r r e l a t i o n s i n Table 15. 2. Regressions Simple regressions of economic c h a r a c t e r i s t i c s on organ weights were c a l c u l a t e d f o r each group. Organ freights, r a t h e r 37 than percentages, were used to permit e a s i e r i n t e r p r e t a t i o n . For example, the r e g r e s s i o n (Table 16) of percent l e a n on heart of 2.44 i n d i c a t e s t h a t f o r each increase of 25 grams i n heart there i s an increase of 2.44% i n l e a n c u t s . W i t h i n treatment regressions are presented i n Table 16 and between treatment regressions i n Table.17. I TABLE 6 Treatment Means of Economic C h a r a c t e r i s t i c s and Feed Consumption Group Treatment No. of pigs Wt. on t e s t l b s . Shrunk weight l b s . D a i l y g a i n l b s . Feed/ body g a i n Feed/ care. g a i n Dress-ing % Lean cuts % Fat cuts % B e l l y % A Pasture 16 91.9 185 1.39 - - 80.0 63.3 22.3 13.7 Cut forage 16 92.8 191 1.51 - - 80.1 60.4 24.6 14.7 D r y l o t 16 92.7 193 1.56 - - 80.7 60.4 24.3 14.6 w 00 14.5 B 0% pomace 6 50.7 190 1.52 391 444 81.3 58.8 26.8 10% pomace 6 50.8 192 1.49 391 451 80.8 59.4 26.7 13.9 20% pomace 6 51.0 188 1.51 408 467 81.2 59.0 26.5 14.6 30% pomace 6 52.0 189 1.53 415 483 80.1 57.8. 28.2 14.0 C 0% pomace 20 50.6 193 1.36 441 514 80.4 62.0 24.5 13.5 20% pomace 20 50.8 191 1.36 468 551 79.8 62.5 24.0 13.5 40% pomace 20 50.9 190 1.27 505 601 78.9 64.1 22.5 13.4 TABLE 7 Treatment Means of Organs Group Treatment Heart L i v e r Spleen Stomach Small i n t e s t i n e Large i n t e s t i n e Adrenals A Pasture .447 2.09 .194 1.030 1.97 1.96 -Cut forage .374 1.93 .168 .844 2.08 2.02 -D r y l o t .390 1.91 .164 .912 2.09 1.97 -B 0% pomace .362 1.92 .163 .879 1.94 1.57 -10% pomace .361 2.22 .172 .739 1.99 • 1.70 -20% pomace .351 1.97 .170 .774 1.99 1.74 -30% pomace .365 2.12 .166 .810 1.96 2.04 -C 0% pomace .413 2.04 .167 .871 1.69 1.81 .557 20% pomace .408 2.08 .162 .761 1.63 2.20 . 535 40% pomace .428 2.22 .159 .326 1.74 2.41 .544 TABLE 8 A n a l y s i s of Variance - Mean Squares of Economic C h a r a c t e r i s t i c s i n Group A Sources of d.f. D a i l y Dressing Lean Fat B e l l y v a r i a t i o n g a i n % cuts cuts % % % Between managements 2 Between r a t i o n s w i t h i n managements 3 Between reps w i t h i n r a t i o n s w i t h i n managements 6 E r r o r 35 ,1102** .94 ,0150 .54 ,0101 1.11 ,0120 1.02 36.41** 16.33** 4.21** 2.41 2.17 .02 1.47 .66 .51 3.69 1.94 .59 t± S i g n i f i c a n t at the 1% l e v e l . TABLE 9 A n a l y s i s of Variance - Mean Squares of Organs i n Group A Sources of v a r i a t i o n d.f. Heart L i v e r Spleen Stomach Small i n t e s t i n e Large i n t e s t i n e Between managements 2 . 0213** .1296 .0038** .0571** .0635 .0035 Between r a t i o n s w i t h i n managements 3 .0005 .0803 .0006 .0057 .1946 .2269 Between reps w i t h i n r a t i o n s w i t h i n managements 6 .0011 .0195 .0016 .0132 .1069 .0263 E r r o r 35 .0018' .0467' .0007 .0097 .1147 .0899 t± S i g n i f i c a n t at the 5% l e v e l . ' - 34 degrfees of freedom. TABLE 10 A n a l y s i s of Variance - Mean Squares of Economic C h a r a c t e r i s t i c s And Feed Consumption i n Group B Sources of d.f. D a i l y Feed consumption Dressing Lean Fat B e l l y v a r i a t i o n g a i n Body Carcass % cuts cuts % g a i n g a i n % % Between reps .0028 92 104 .15 .70 .12 .24 Between pomace l e v e l s w i t h i n reps 6 E r r o r 16 .0171 .0293 730 645 1246 1005 1.72 5.26 3.90 1.81 2.54 1.72 .79* .22 ± S i g n i f i c a n t a t the 5% l e v e l . TABLE 11 A n a l y s i s of Variance - Mean Squares of Organs i n Group B Sources of v a r i a t i o n d.f. Heart L i v e r Spleen Stomach Small Large i n t e s t i n e i n t e s t i n e Between reps Between pomace l e v e l s w i t h i n reps E r r o r 6 16 ,0019 .0451 .0005 .0053 ,0003 .0421 .0003 .0111 ,0014 .0357 .0005 .0070 .0210 .0414 .0895 .0160 .1243 .0543 TABLE 12 A n a l y s i s of Variance - Mean Squares of Economic C h a r a c t e r i s t i c s And Feed Consumption i n Group C Sources of v a r i a t i o n d.f. D a i l y g a i n Feed consumption Body carcass g a i n g a i n Dressing % Bean cuts % Fat cuts % B e l l y % Between pomace l e v e l s 2 .0618* 20485** 38135** 10.54** 25.22** fc20.60* * .09 Between p r o t e i n l e v e l s 1 .0011 633 851 .24 .02 .27 .16 Between r e p l i c a t e s 1 .0051 2954 3053 .81 14.51* 4.27 2.95* I n t e r a c t i o n s ; P r o t e i n x reps 1 .0022 2101 3840 1.74 4.64 1.73 .71 Pomace x reps. 2 .0032 655 1915 2.26 1.28 .14 .59 P r o t e i n x pomace 2 .0018 17 117 .78 .27 .59 .01 P r o t e i n x pomace x reps. 2 .0179 1222 1749 5.10 2.74 5.54 .65 E r r o r 48 .0161 2964 3961 1.65 5.39 2.50 .55 ft S i g n i f i c a n t at the 5% l e v e l . £& S i g n i f i c a n t at the 1% l e v e l . TABLE 13 A n a l y s i s of Variance - Mean Squares of Organs i n Group C Sources of v a r i a t i o n d.f:;.. Heart L i v e r Spleen Stomach Small i n t e s t i n e Large i n t e s t i n e Adrenals Between pomace l e v e l s 2 .0021 .1758 .0003 .0608** .0719 1.9160** .0024 Between p r o t e i n l e v e l s 1 .0005 .1066 .0002 .0005 .0114 .0035 .0026 Between r e p l i c a t e s 1 .0066 .0380 .0006 .0375 .0799 .0017 .0001 I n t e r a c t i o n s : P r o t e i n x reps. 1 .0002 .0177 .0000 .0031 .0433 .0113 .0024 Pomace x reps. 2 .0007 .2644** .0008 .0024 .0530 .1285 .0055 P r o t e i n x pomace 2 .0002 .0971 .0004 .0203 .0075 .1891** .0118 P r o t e i n x pomace x reps. 2 .0008 .0124 .0001 .0198 .0124 .1195 .0399** E r r o r 48 .0012 .0367 .0009 .0084 .0454 .0528 .0047 & S i g n i f i c a n t at the b% l e v e l . &ft S i g n i f i c a n t at the 1% l e v e l . 46 TABLE 14 Simple C o r r e l a t i o n s W i t h i n Treatments by Experimental Groups C h a r a c t e r i s t i c s Group A Group B Group C D a i l y g a i n & feed/body g a i n - -.53* -.59** D a i l y g a i n & feed/carcass g a i n - -.51* -.55** D a i l y g a i n & dressing % -.41* -.04 -.24 D a i l y g a i n & l e a n cuts % -.10 -.66* .04 D a i l y gain' & f a t cuts % .04 .68* -.11 D a i l y g a i n & b e l l y % .16 .33 .12 D a i l y g a i n & heart -.17 .39 -.35* D a i l y g a i n & l i v e r .14 .33 .31* D a i l y g a i n & spleen -.61** -.38 .02 D a i l y g a i n & stomach .34* .13 -.18 D a i l y g a i n & small i n t e s t i n e .41* .12 .19 D a i l y g a i n & l a r g e i n t e s t i n e .47* .13 .40** D a i l y g a i n & adrenals - - -.24 Feed/body g a i n & dressing % - .00 .20 Feed/body g a i n & l e a n cuts % - .26 -.44** Feed/body g a i n & f a t cuts % - -.25 .49** Feed/body g a i n & b e l l y % - -.19 .06 Feed/body g a i n & heart - -.04 .29* Feed/body g a i n & l i v e r - .02 -.30* Feed/body g a i n & spleen - .60* .17 Feed/body g a i n & stomach - -.16 .09 Feed/body g a i n & small i n t e s t i n e - -.03 Feed/body g a i n & l a r g e i n t e s t i n e - .01 -.31* Feed/body g a i n & adrenals - - .38** Feed/carcass g a i n & dressing % - -.26 •^•a-*-Feed/carcass g a i n & l e a n cuts % - .27 -.41** Feed/carcass g a i n & f a t cuts % - -.30 .44** Feed/carcass g a i n & b e l l y % - .07 .08 Feed/carcass g a i n & heart - -.10 .32* Feed/carcass g a i n & l i v e r - ;T.16 -.18 Feed/carcass g a i n & spleen - .51* .19 Feed/carcass g a i n & stomach - -.09 .17 Feed/carcass g a i n & small i n t e s t i n e - .08 -.12 Feed/carcass g a i n & l a r g e i n t e s t i n e - .09 Feed/carcass g a i n & adrenals - - .36* Dressing % & l e a n cuts % -.26 -.10 -.25 Dressing % k f a t cuts % .38* .21 .53** Dressing % & b e l l y % -.02 -.24 -.09 D ressing % & heart -.08 .08 -.19 47 TABLE 14 (continued) C h a r a c t e r i s t i c s Group A Group B Group C Dressing % & l i v e r . Dressing % & spleen Dressing % & stomach D ressing % & small i n t e s t i n e Dressing % & l a r g e i n t e s t i n e Dressing % & adrenals Lean cuts % & b e l l y % Lean cuts % & heart Lean cuts % & l i v e r Lean cuts % & spleen Lean cuts % & stomach Lean cuts % & small i n t e s t i n e Lean cuts % & l a r g e i n t e s t i n e Lean cuts % & adrenals Fat cuts % & b e l l y % Fat cuts % & heart F a t cuts % & l i v e r Fat cuts % & spleen Fat cuts % & stomach Fat cuts % 8c small i n t e s t i n e F a t cuts % & l a r g e i n t e s t i n e Fat cuts '% & adrenals B e l l y %. & heart B e l l y % & l i v e r B e l l y % & spleen B e l l y % & stomach B e l l y % & small i n t e s t i n e B e l l y % & l a r g e i n t e s t i n e B e l l y % & adrenals Heart & l i v e r Heart & spleen Heart & stomach Heart & small i n t e s t i n e Heart & l a r g e i n t e s t i n e Heart & adrenals L i v e r spleen L i v e r & stomach L i v e r & small i n t e s t i n e -.56** -.51* -.55** -.22 .21 .11 -.63 -.26 -.48** -.47** -.40 -.58** -.54** -.26 -.58** .17 -.79** -.69** -.53** .49** .06 .31* .06 -*10 .16 .09. -.08 .20 .33* .01 .05 -.01 -.26 .21 -.00 -.03 .16 -.02 .53** .48* .15 -.45** .09 -.24 -.13 .04 -.21 -.03 .01 -.18 -.38* -.06 -.09 -.04 .12 -.33* .08 .02 -.26 -.00 -.42* -.05 -.25 .08 .26 .04 .16 .24 -.13 -.15 .13 .06 .09 .56* .18 .15 .15 .16 .05 .03 .43 -.07 .27 -.08 .41** —T01 .22 .25 -.23 .19 -.10 -.13 .27 - . 0 9 ^ .75** -.31 ~ -.24 -.05 .46** .6§** .29* .60** .60* .60** 48 TABLE 14 (continued) C h a r a c t e r i s t i c s Group A Group B Group C L i v e r & l a r g e i n t e s t i n e L i v e r & adrenals .70** .66** .06 Spleen & stomach Spleen & small i n t e s t i n e Spleen & l a r g e i n t e s t i n e Spleen & adrenals -.21 -.59** -.31 .05 .14 -.23 -.02 -.10 .02 .28 Stomach & small i n t e s t i n e Stomach & l a r g e i n t e s t i n e Stomach & adrenals .45** .40* .52* .67** .43** -.10 Small i n t e s t i n e & l a r g e i n t e s t i n e Small i n t e s t i n e & adrenals .52* .20 .60** -.34* Large i n t e s t i n e & adrenalw - - -.16 d.f. 34 15 47 t. S i g n i f i c a n t at the b% l e v e l , ftft S i g n i f i c a n t at the 1% l e v e l . 49 TABLE 15 Simple C o r r e l a t i o n s Between Treatments by Experimental Groups C h a r a c t e r i s t i c s Group A Group B Group C D a i l y g a i n & feed/body g a i n - .09 -.91 D a i l y g a i n & feed/carcass g a i n - .06 -.91 D a i l y g a i n & dressing % .93 .24 .88 D a i l y g a i n & l e a n cuts % -.89 -.83* -.98 D a i l y g a i n & f a t cuts % .92 .82* .97 D a i l y g a i n & b e l l y $ .82 .33 .99 D a i l y g a i n & heart -.82 .12 .98 D a i l y g a i n & l i v e r -.84 .69 -.98 D a i l y g a i n & spleen -.97 -.42 .81 D a i l y g a i n & stomach -.87 .46 -.11 D a i l y g a i n & small i n t e s t i n e .99 .31 -.81 D a i l y g a i n & l a r g e i n t e s t i n e .99 .35 .77 D a i l y g a i n & adrenals - - .10 Feed/body g a i n & dressing % - -.36 -.99** Feed/body g a i n & l e a n cuts % - -.35 .98 Feed/body g a i n & f a t cuts % - .29 -.98 Feed/body g a i n & b e l l y % - .26 -.84 Feed/body g a i n & heart - -.43 .79 Feed/body g a i n & l i v e r - .86 .98 Feed/body g a i n & spleen - -.25 -.98 Feed/body g a i n & stomach - -.35 -.32 Feed/body g a i n & small i n t e s t i n e - -.53 .48 Feed/body g a i n & l a r g e i n t e s t i n e ' - .72 .98 Feed/body g a i n & adrenals - - -.51 Feed/carcass g a i n & dressing % - -.56 -.99** Feed/carcass g a i n & l e a n cuts % - -.26 .98 Feed/carcass g a i n & f a t cuts % - .29 -.98 Feed/carcass g a i n & b e l l y l $ j f* .02 -.84 Feed/carcass g a i n & heart - -.25 .79 Feed/carcass g a i n & l i v e r - .33 .98 F eed/carcass g a i n & spleen - -.10 -.98 Feed/carcass g a i n & stomach - -.48 -.31 Feed/carcass g a i n & small i n t e s t i n e - -.45 .49 Feed/carcass g a i n & l a r g e i n t e s t i n e - .84* .97 Feed/carcass g a i n & adrenals - - -.51 Dressing % & l e a n cuts % -.66 -.30 -.98 Dressing % & f a t cuts % .71 ~' 0 0^ * S 8 Dressing % & b e l l y % .55 .79* .86 Dressing % & heart -.54 -.52 -.81 Dressing % & l i v e r -.58 -.10 -.98 50 TABLE 15 (continued) C h a r a c t e r i s t i c s Group A Group B Group C Dressing % & spleen •Dressing % & stomach Dressing % & small i n t e s t i n e Dressing % & l a r g e i n t e s t i n e Dressing % & adrenals Lean cuts % & b e l l y % Lean cuts % & heart Lean cuts % & l i v e r Lean cuts % & spleen Lean cuts % & stomach Lean cuts % & small I n t e s t i n e Lean cuts % & l a r g e i n t e s t i n e Lean cuts % & adrenals Fat cuts % & b e l l y % F a t cuts % & heart Fat cuts % & l i v e r Fat cuts fo & spleen Fat cuts % k stomach Fat cuts % & small i n t e s t i n e Fat cuts % & l a r g e i n t e s t i n e Fat cuts % & adrenals B e l l y % & heart B e l l y % & l i v e r B e l l y i & spleen B e l l y % & stomach B e l l y % & small i n t e s t i n e B e l l y % & l a r g e i n t e s t i n e B e l l y % & adrenals Heart & l i v e r Heart & Spleen Heafct & stomach Heart & small int e s t i n e Heart & l a r g e i n t e s t i n e Heart & adrenals L i v e r & spleen L i v e r & stomach L i v e r & small i n t e s t i n e L i v e r & l a r g e i n t e s t i n e L i v e r & adrenals -.81 -.40 .97 -.63 .40 .28 .96 .09 -.52 .87 -.69 -.92 - - .48 -.99 -.05 -.94 .99 .33 .99 -.73 1.00** .97 .82* .91 .99* —. 23 -.10 -.84 -.05 .67 -.94 -.39 .89 - • - -.31 .98 .02 .93 -.98 -.06 -.90 -.98 .86$ -.9944 -.99 -.70 .92 -.99 .11 .12 .88 .20 -.65 .96 .58 -.90 - - .33 -1.00** -.72 -1.00** -1.00** -.04 -.94 -.93 -.57 .72 -.99 .35 -.26 .76 -.31 -.89 .88 — • 28 -.67 - - -.04 .99** -.04 .91 .93 .54 -.66 .99 .35 .33 -.75 .31 .92 -.88 .10 .61 - - .13 .94 -.38 -.91 .99** -.11 -.10 -.77 .24 .66 -.89 .64 .89 — — -.31 51 TABLE 15 (continued) C h a r a c t e r i s t i c s Group A Group B Group ( Spleen & stomach Spleen & small i n t e s t i n e Spleen & l a r g e i n t e s t i n e Spleen & adrenals .96 -.94 -.99 -.14 .14 .09 .50 - .30 -.99* .67 Stomach & small i n t e s t i n e Stomach & l a r g e i n t e s t i n e Stomach & adrenals -.82 -.92 -.19 -.41 .68 -.55 .98 Small i n t e s t i n e & l a r g e i n t e s t i n e Small i n t e s t i n e & adrenals .97 .00 .85 .50 Large i n t e s t i n e & adrenals - - -.71 d.f. 1 5 1 ± S i g n i f i c a n t at the b% l e v e l . S i g n i f i c a n t at the 1% l e v e l . 52 TABLE 16 Regressions W i t h i n Treatments by Experimental Groups C h a r a c t e r i s t i c s Group A Group B Group C D a i l y g a i n on heart -.05 .18 -.12* D a i l y g a i n on l i v e r .01 .02 .02* D a i l y g a i n on spleen -.24 -.26 -.01 D a i l y g a i n on stomach .04 .01 -.03 D a i l y g a i n on small i n t e s t i n e .01 .01 * ^ - A - * D a i l y g a i n on l a r g e i n t e s t i n e .02 .01 .02** D a i l y g a i n on adrenals - - -.05 Feed/body g a i n on heart - -2.61 41.48** Feed/body g a i n on l i v e r - 2«34 -8.18* Feed/body g a i n on spleen - 60.41* 28.82 Feed/body g a i n on stomach - -5.16 5.49 Feed/body g a i n on small i n t e s t i n e - -.23 -7.13 Feed/body g a i n on l a r g e i n t e s t i n e - .08 -6.97* Feed/body g a i n on adrenals - - 30.24* Feed/carcass g a i n on heart - -8.08 53.00 s • Feed/carcass g a i n on l i v e r - 2.75 -5.55 Feed/carcass g a i n on spleen - 64. 17* 37.01 Feed/carcass g a i n on stomach - -3.65 12.46 Feed/carcass gaon on small i n t e s t i n e - .89 -4.56 Feed/carcass g a i n on l a r g e i n t e s t i n e - 1.43 -5.52 Feed/carcass g a i n on adrenals - - 32.89* Lean cuts % on heart Lean cuts % on l i v e r Lean cuts % on spleen Lean cuts % on stomach Lean cuts % on small i n t e s t i n e Lean cuts % on l a r g e i n t e s t i n e Lean cuts % on adrenals Fat cuts % on heart Fat cuts % on l i v e r Fat cuts % on spleen Fat cuts % on stomach Fat cuts % on small i n t e s t i n e Fat cuts % on l a r g e i n t e s t i n e Fat cuts % on adrenals B e l l y % on heart 2.44** -.23 1.52* .06 -.09 ,15 .QZ -.49 1.15 .63* .01 .11 -.00 -.14 .22** -.00 -.02 .12 - - -.05 -1.60** .30 -1.03 -.09 .03 -.16 -1.54 .07 -.85 -.51* -.10 -.16 -.02 .05 -.30 -.04 -.01 -.17 - - -.00 -.84* -.07 -.49 53 TABLE 16 (continued) C h a r a c t e r i s t i c s Group A Group B Group C B e l l y % on l i v e r B e l l y % on spleen B e l l y % on stomach B e l l y % on small i n t e s t i n e B e l l y % on l a r g e i n t e s t i n e B e l l y % on adrenals .03 -.45 -.11 .02 .04 .06 .04 .08 .09* .03 .02 .30 .05 .07 .05 .05 d.f. 34 15 47 ± S i g n i f i c a n t at the 5% l e v e l , ftft S i g n i f i c a n t at the 1% l e v e l . The u n i t s are: g a i n =.1 lb./das'-; feed/body g a i n =1 l b . per 100 l b s . l i v e weight gain ; feed/carcass g a i n =1 l b . per 100 l b s . carcass g a i n ; % l e a n , f a t and b e l l y = 1% i n c o l d carcass minus head, f e e t and kidneys; heart - 25 grams; l i v e r = 140 grams; spleen = 10 grams; stomach = 60 grams; small i n t e s t i n e = 140 grams; l a r g e i n t e s t i n e = 140 grams; adrenals = 375 m i l l i g r a m s . 54 TABLE 17 Regressions Between Treatments by Experimental G roups C h a r a c t e r i s t i c s Group A Group B Group C D a i l y g a i n on heart -.21 .10 -.48 D a i l y g a i n on l i v e r -.08 .04 -.06 D a i l y g a i n onspleen -.47 -.27 1.03 D a i l y g a i n on stomach -.11 .06 -.01 D a i l y g a i n on small i n t e s t i n e .13 .02 -.10 D a i l y g a i n on l a r g e i n t e s t i n e .58 .01 -.01 D a i l y g a i n on adrenals - - .05 Feed/body g a i n on heart -7.G1 225.36 Feed/body g a i n on l i v e r - 3.43 32.13 Feed/body g a i n on spleen - -31.87 -723.26 Feed/body g a i n on stomach — . -9.57 -19.74 Feed/body g a i n on small i n t e s t i n e — -7.17 32.13 Feed/body g a i n on l a r g e i n t e s t i n e - 6.37 9.42 Feed/body g a i n on adrenals - - -148.78 Feed/carcass g a i n on heart -53.19 308.38 Feed/carcass g a i n on l i v e r — 5.70 43.89 Feed/carcass g a i n on spleen — -17.58 -985.89 Feed/carcass g a i n on stomach — -15.00 -26.61 Feed/carcass g a i n on small i n t e s t i n e - -8.11 44.12 Feed/carcass g a i n on l a r g e i n t e s t i n e - 9.63 12.80 Feed/carcass g a i n on adrenals - - -201.71 Lean cuts % on heart 4.44 4.50 8.70 Lean cuts % on l i v e r 1.72 Lean cuts % on spleen 8.59 8.97s tt 22.52 Lean cuts % on stomach 2.40 -.53 -.20 Lean cuts % on small i n t e s t i n e -1.95 -.06 1.49 Lean cuts % on l a r g e i n t e s t i n e -9.87 -.30 .29 Lean cuts % on adrenals - - -3.02 Fat cuts % on heart -2.93 -•69. -8.10. Fat cu$s % on l i v e r -1.13 .83 s 1 -1.04-Fat cuts % on spleen -5.83 -6.55 21.56 Fat cuts % on stomach -1.60 .21 .25 Fat cuts % on small i n t e s t i n e 1.36 .21 -1.36 Fat cuts % on l a r g e i n t e s t i n e 6.76 .38 - .27 Fat cuts % on adrenals - - 3.05 B e l l y % on heart -1.53 -3.81 -.60* 55 TABLE 17 (continued) C h a r a c t e r i s t i c s Group A Group B Group C B e l l y % on l i v e r -.59 -.02 -.07 B e l l y % on spleen -2.80 -.24 . 1.11 B e l l y % on stomach -.82 .31 -.03 B e l l y % on small i n t e s t i n e .60 -.14 -.12 B e l l y % on l a r g e i n t e s t i n e 3.15 -.08 -.01 B e l l y % on adrenals -.03 d.f. 1 5 1 ± S i g n i f i c a n t at the 5% l e v e l . ftfc S i g n i f i d a n t at the 1% l e v e l . The u n i t s are: g a i n = .1 lb./day; feed/body g a i n = 1 l b . per 100 l b s . l i v e weight gain ; feed/carcass g a i n = 1 l b . per 100 l b s . carcass g a i n ; 1% l e a n , f a t and b e l l y = 1% i n c o l d carcass.minus head, feed and kidneys; heart = 25 grams; l i v e r = 140 grams; spleen = 10 grams; stomach = 60 grams; small i n t e s t i n e = 140 grams; l a r g e i n t e s t i n e = 140 grams; adrenals = 375 m i l l i g r a m s . 56 IV. DISCUSSION A. Sex E f f e c t s The s i g n i f i c a n t sex d i f f e r e n c e s i n groups A and C agree w i t h those noted i n the l i t e r a t u r e . In both groups males grew f a s t e r , produced lower percent l e a n c u t s , higher percent f a t c u t s , higher percent b e l l y and smaller spleens than females. Males a l s o had smaller hearts but the d i f f e r e n c e was s i g n i f i c a n t i n Group C only. F a s t e r growth r a t e i n male pigs has been e s t a b l i s h e d by other workers i n c l u d i n g Lacy (1932), Donald (1940), Crampton and Ashton (1945 and 1946a), Bennet and Coles (1946) and Fred-een (1953). F a t t e r carcasses i n males have been found a l s o by many ;• workers i n c l u d i n g Crampton and Ashton (1945 and 1946a), Bennet and Coles (1946) and Fredeen (1953). Smaller hearts and spleens i n c a s t r a t e male pigs were r e -ported by C r i l e and Quiring (1940). The l i t e r a t u r e does not o f f e r p o s s i b l e explanations of these sex d i f f e r e n c e s i n heart and spleen s i z e . That the heart and spleen are probably i n -fluenced by common cause i s i n d i c a t e d by the p o s i t i v e c o r r e l a t -ions between these organs obtained by Latimer (1947) and B l a c k -more (1955). I f a strong p h y s i o l o g i c a l r e l a t i o n s h i p does e x i s t i t i s l i k e l y governed by the blood f l o w i n the body since the heart maintains t h i s flow and the spleen stores red blood c e l l s f o r use i n periods when blood flow i s r a p i d such as during d i g -e s t i v e processes or e x e r c i s e . D i f f e r e n c e s i n heart and spleen . s i z e between the sexes could p o s s i b l y r e s u l t from d i f f e r e n c e s 57 i n metabolic r a t e . Walter and Addis (1939) found smaller hearts i n animals w i t h reduced metabolic r a t e . This f a c t o r could poss-i b l y a l s o a f f e c t the spleen s i z e since i t i s so c l o s e l y a s s o c i a t -ed w i t h the use of blood i n the body through i t s r o l e i n the formation and d e s t r u c t i o n of red blood c e l l s . C a s t r a t i o n may be a c o n t r i b u t i n g f a c t o r to any d i f f e r e n c e i n metabolic r a t e . I t i s recognized that c a s t r a t i o n a f f e c t s the endocrine r e l a t i o n s h i p s i n the body w i t h r e s u l t i n g r e d u c t i o n i n metabolic r a t e (Maynard and L o o s l i , 1956). B. Treatment E f f e c t s 1. Group A (a) D a i l y g a i n . Reduced g a i n i n the pasture fed pig s could r e s u l t from g r e a t e r a c t i v i t y . These pigs were f r e e to move over a much l a r g e r area than those i n d r y l o t . The increased a c t i v i t y would r e q u i r e more energy from the n u t r i e n t s consimed w i t h l e s s remaining f o r growth. This r e s t r i c t i o n i n a v a i l a b l e n u t r i e n t s would mean that the pigs could not a t t a i n the growth r a t e of which they were g e n e t i c a l l y capable. (b) Lean and f a t . The higher pereent l e a n and lower percent f a t i n the pasture-fed p i g s can be explained a l s o on the b a s i s of greater a c t i v i t y . Thus, the more a c t i v e p i g has l e s s n u t r i -ents l e f t f o r the d e p o s i t i o n of f a t i n the body. Increase i n l e a n through r e s t r i c t i o n of n u t r i e n t s has been p r e v i o u s l y demon-s t r a t e d i n work by E l l i s and Z e l l e r (1934), McMeekan (1940) and McMeekan and Hammond (1940). (c) B e l l y . Lower percent b e l l y i n the pasture-fed pigs may 58 be a r e s u l t of l e s s f a t d e p o s i t i o n . (d) Heart. A c t i v i t y w i l l increase heart s i z e according to work by Kulb ( c i t e d by Joseph, 1908), McMeekan (1940) and Brody and K i b l e r (1941). The increased heart s i z e of the pasture-fed pigs i s then to be expected. (e) Spleen. Larger spleens i n the pasture-fed p i g s could r e s u l t from exposure to m i l d i n f e c t i o n s according to work by Ahronheim (1957). This worker reported increased spleen s i z e r e s u l t i n g from chronic and acute disease. Increased body responses due to greater nervous s t i m u l i i s considered as another p o s s i b l e cause of l a r g e r spleens i n the pastiire p i g s . That nervous s t i m u l i can a f f e c t spleen s i z e has been shown by Hargis and Mann(l9S5). Repeated s t i m u l i would be expected to increase spleen a c t i v i t y w i t h a r e s u l t i n g increase i n s i z e i f the spleen r e a c t s to increased a c t i v i t y i n the same way as other organs. (f) Stomach. The increased stomach weight of the pasture pigs i s expected to be a r e s u l t of the d i e t eaten by these p i g s . One p o s s i b i l i t y i s that the increase was due to s t i m u l a t i o n from forage consumed. Since forage contains l e s s n u t r i e n t s per u n i t volume than g r a i n concentrate the pigs would eat a g r e a t e r volume of i t - w i t h a r e s u l t i n g increase i n stomach s i z e to accomodate i t . I f t h i s were the case, however, i t would be expected from work by Wierda (1950) and Bohman et a l (1955) that the l a r g e i n t e s t i n e would show a corresponding increase i n s i z e . However, t h i s does not occur i n these p i g s . A second p o s s i b l e e x p l a n a t i o n would assume that the pigs 59 on pasture ate more g r a i n w h i l e they were at the feeder than those i n d r y l o t . The pasture pigs were able to get as f a r as 150 f e e t away from the feeder whereas the d r y l o t pigs could get only about 7 feed away from the feeder. The p i g i n d r y l o t would be expected to eat more o f t e n j u s t from the p r o x i m i t y of h i s feeder. I f the pasture p i g ate l e s s o f t e n he would be expected to have a l a r g e r a p p e t i t e and eat a g r e a t e r volume of feed per feeding. This would d i s t e n d the stomach and repeated many times during the pig's l i f e could conceivably increase the stomach w a l l t i s s u e and i t s weight. In t h i s case an increase i n the l a r g e i n t e s t i n e s i z e would not be expected since the food being handled i s the g r a i n concentrate and the residue passing i n t o the l a r g e i n t e s t i n e would not be any b u l k i e r than that consumed by the d r y l o t p i g s . The second e x p l a n a t i o n above seems to f i t the s i t u a t i o n best. Since, however, the pigs on pasture were consuming some forage, i t i s l i k e l y t h a t both f a c t o r s were having some influence on the stomach s i z e . 2. Group B (a) Feed per u n i t g a i n . The d i f f e r e n c e s i n t h i s c h a r a c t e r -i s t i c are not s i g n i f i c a n t but a strong trend to g r e a t e r feed consumption per u n i t g a i n as pomace l e v e l increases can be read-i l y seen. Apparently the d i g e s t i b i l i t y of the feed i s decreas-ing as the pomace l e v e l i ncreases. This i s to be expected due to the h i g h crude f i b e r content of the pomace. R e s u l t s by L l o y d and Crampton (1955) i n d i c a t e that i n c r e a s i n g f i b e r l e v e l 60 decreases the d i g e s t i b i l i t y of n u t r i e n t s i n a r a t i o n . (b) B e l l y . The s i g n i f i c a n t d i f f e r e n c e i n t h i s c h a r a c t e r -i s t i c does not appear to have a p l a u s i b l e e x p l a n a t i o n i n physio-l o g i c a l terms. There i s , of course, one chance i n twenty t h a t the magnitude of d i f f e r e n c e observed here was due to causes other than the treatment d i f f e r e n c e of t h i s experiment. (c) Large i n t e s t i n e . D i f f e r e n c e s i n t h i s c h a r a c t e r i s t i c are not s i g n i f i c a n t but a strong trend to greater l a r g e i n t e s t -ine weight w i t h i n c r e a s i n g pomace l e v e l i s apparent. This could again be the r e s u l t of lower d i g e s t i b i l i t y i n the h i g h pomace r a t i o n s . The residue passed i n t o the l a r g e i n t e s t i n e i n t h i s case would be q u i t e bulky and tend to s t i m u l a t e increases i n i n t e s t i n e s i z e . 3. Group C (a) D a i l y g a i n . The decrease i n g a i n w i t h increased pomace l e v e l can be a t t r i b u t e d to lowered d i g e s t i b i l i t y of the r a t i o n as pomace l e v e l i n c r e a s e s . The p i g i s unable to consume s u f f i c -i e n t of the b u l k i e r 40% pomace r a t i o n to provide a l l the n u t r -i e n t s needed f o r maximum growth. The lowering of d i g e s t i b i l i t y by adding pomace can be seen i n r e s u l t s from the 0 ..and 20% pomace r a t i o n s . In these two r a t i o n s the d a i l y g a i n i s the same. However, w i t h the 20% pomace r a t i o n the feed consumption per u n i t g a i n has markedly increased, i n d i c a t i n g that more feed has been r e q u i r e d to o b t a i n the same a s s i m i l a t e d n u t r i e n t s . (b) Feed per u n i t g a i n . Increased feed consumption per u n i t g a i n by pigs on the 40% r a t i o n a r i s e s from both an i n c r e a s -ed maintenance requirement due to slower g a i n and lower 61 d i g e s t i b i l i t y of the r a t i o n . That the increase i s not due e n t i r e l y to maintenance f o l l o w s from the e a r l i e r o b s e r v a t i o n that feed consumption increased when 20% pomace was added even though growth r a t e was the same. This can be seen a l s o i n r e s -u l t s from Group B where growth at 30% pomace was higher than th a t at 0% pomace y e t the feed consumption per u n i t g a i n was higher at the 30% l e v e l . (c) Dressing percent. Lower dressing percentage In the pigs f e d 40% pomace could r e s u l t from increased organ s i z e , e s p e c i a l l y d i g e s t i v e t r a c t , due to the bulky nature of the r a t -i o n . Coey and Robinson (1955) and Bohman et a l (1955) obtained r e s u l t s which would support t h i s . E f f e c t i v e r e s t r i c t i o n of the n u t r i e n t a s s i m i l a t i o n r e s u l t i n g from lower d i g e s t i b i l i t y of the hi g h pomace r a t i o n may have lowered the dressing percentage as found i n work by Haines et a l (1956). (d) Lean and f a t . The higher p r o p o r t i o n of l e a n cuts i n pigs from the 40% pomace l e v e l would r e s u l t from the r e s t r i c t e d a s s i m i l a t i o n of n u t r i e n t s due to the low d i g e s t i b i l i t y of the r a t i o n . This e f f e c t has been e s t a b l i s h e d i n work by E l l i s and Z e l l e r (1934), McMeekan (1940) and McMeekan and Hammond (1940). (e) L i v e r . The increase i n l i v e r s i z e with increase i n pomace l e v e l would i n d i c a t e g r e a t e r a c t i v i t y of t h i s organ, a view supported by work by Walter and Addis (1939). One poss-i b l e cause of greater l i v e r a c t i v i t y may be a shortage of energy producing n u t r i e n t s d i g e s t e d by the animal. I f t h i s were the case, any p r o t e i n a v a i l a b l e over t h a t r e q u i r e d f o r t i s s u e main-tenance and growth would be deaminized by the l i v e r to produce 62 keto acids which can be used i n the production of energy. This process plus the conversion of the re l e a s e d ammonia to urea would increase l i v e r a c t i v i t y c o n s i d e r a b l y . P o i n t s supporting t h i s p o s s i b i l i t y are: 1. I t has been shown th a t i n feed w i t h h i g h crude f i b e r content the d i g e s t i b i l i t y of the simpler carbohydrates i s low (Maynard and L o o s l i , 1956). Thus the hi g h pom-ace r a t i o n would tend to be l e s s d i g e s t i b l e . 2. P r o t e i n content of the h i g h pomace r a t i o n was apparent-l y s u f f i c i e n t since no i n t e r a c t i o n was observed between pomace l e v e l and p r o t e i n l e v e l . A second p o s s i b l e e x p l a n a t i o n f o r the increased l i v e r s i z e i s i n d i c a t e d from work by Gibbons and Rose (1950) and Wilcox et a l (1953). In these papers the feeding of sucrose produced heavier l i v e r s i n swine as a r e s u l t of greater carbohydrate storage i n the l i v e r . I t may be tha t the d i g e s t i b l e carbohy-drate of the pomace i s mainly simple sugars and could produce a s i m i l a r e f f e c t . However the observations already made tha t • high crude f i b e r r a t i o n s are l e s s d i g e s t i b l e and that s u f f i c -i e n t n u t r i e n t s are not a v a i l a b l e to permit maximum growth sug-gest that the above e x p l a n a t i o n i s not tenable here. I t i s suggested, t h e r e f o r e , that increased l i v e r a c t i v i t y i s probably r e s p o n s i b l e f o r the increase i n l i v e r s i z e , observed i n t h i s experiment. (f()> Stomach. While the d i f f e r e n c e s i n stomach weight app-ear to be somewhat i n c o n s i s t e n t they are s t a t i s t i c a l l y s i g n i f i -cant. When the trend of Stomach weights between pomace l e v e l s is 63 compared w i t h the trend i n Group B a s i m i l a r i t y can be seen. In both groups the highest stomach weight i s i n the pigs r e c e i v i n g no pomace w i t h lower weights at the 20% pomace l e v e l i n c r e a s i n g again above 20% pomace. I t would appear t h a t some f a c t o r i n connection w i t h the a d d i t i o n of pomace to the r a t i o n i s a f f e c t i n g stomach s i z e . From the work of Wussow and Weniger (1954) and Bohman et, a l (1955) a strong trend to i n c r e a s i n g stomach weight w i t h i n c r e a s -ing pomace l e v e l would be expected. This would e x p l a i n the i n -crease i n stomach s i z e above 20% pomace. The apparent trend of decreasing stomach s i z e from 0% pomace to 20% pomace, however, must be explained on some other b a s i s . One p o s s i b i l i t y could be the amount of f a t deposited i n the t i s s u e of the stomach w a l l . The pigs on 0% pomace tended to be s l i g h t l y f a t t e r than those on 20% pomace. Perhaps t h i s added f a t n e s s was s u f f i c i e n t t h a t more f a t was deposited i n the stomach w a l l . (g) Large i n t e s t i n e . The increase i n l a r g e i n t e s t i n e weight i s a t t r i b u t a b l e to the increase i n b u l k of the r a t i o n as pomace l e v e l increased. This agrees w i t h f i n d i n g s of Wierda (1942 and 1950) and Bohman et a l (1955). I t a l s o p a r a l l e l s r e s u l t s i n group B of the present study. C. R e l a t i o n s h i p s 1. C o r r e l a t i o n s w i t h i n treatments. (a) Between economic c h a r a c t e r i s t i c s . The high negative c o r r e l a t i o n s between d a i l y g a i n and feed per 100 l b s . body g a i n and feed per 100 l b s . carcass g a i n agree w i t h r e s u l t s of Evvard 64 et a l (1927), Lush (1936), S t o t h a r t (1938), Z e l l e r (1944), Dick-erson (1947), Warren and Dickerson (1952) and Fredeen (1953). This strong r e l a t i o n s h i p would r e s u l t from the higher maintenance requirement f o r the slow-gaining p i g . The negative c o r r e l a t i o n s between d a i l y g a i n and d r e s s i n g percentage agree i n d i r e c t i o n w i t h those of Blackmore (1953) but are lower i n magnitude. This r e l a t i o n s h i p could be a r e s u l t of the faster-growing p i g eating more feed per u n i t of time. This would tend to increase the i n t e s t i n a l t r a c t s i z e . This greater use of feed would a l s o increase the heart and l i v e r s i z e to some degree although the change i n heart s i z e would i n f l u e n c e the . dre s s i n g percentage very l i t t l e . The p o s i t i v e c o r r e l a t i o n s between d a i l y g a i n and percent b e l l y could i n d i c a t e that d e p o s i t i o n of f a t i s i n f l u e n c i n g the p r o p o r t i o n a l b e l l y weight since Donald (1940), Bennet and Coles (1946), Blunn and Baker (1947), Dickerson (1947) and Blackmore (1953) have shown that f a s t e r g a i n i n g pigs tend to be f a t t e r . The negative c o r r e l a t i o n s between dressing percent and l e a n cuts and the p o s i t i v e c o r r e l a t i o n s between dre s s i n g percent and f a t cuts agree w i t h those of Jesperson and Madsen (reported by Lush, 1936), Aunan and Winters (1949) and Blackmore (1953). They are higher than those of Blackmore but lower than those of Aunan and Winters. The l a t t e r workers, however, appeared to include breed c l a s s d i f f e r e n c e s which is' not the case i n the present study nor i n t h a t of Blackmore. This r e l a t i o n s h i p would i n d i c a t e that f a t t e n i n g pigs deposit p r o p o r t i o n a t e l y more f a t on the carcass than on the i n t e r n a l organs. 65 The h i g h negative c o r r e l a t i o n s between percent l e a n cuts and percent b e l l y and the high p o s i t i v e c o r r e l a t i o n between per-cent f a t cuts and b e l l y would i n d i c a t e that the b e l l y i s i n f l u e n -ced more by f a t d e p o s i t i o n t h a i i t i s by l e a n d e p o s i t i o n i n the body. This would i n d i c a t e that the b e l l y should be c l a s s i f i e d as a f a t cut r a t h e r than a l e a n cut i n s t u d i e s where f a t and l e a n content of the carcass i s being considered. (b) Between economic c h a r a c t e r i s t i c s and organs. The pos-i t i v e c o r r e l a t i o n between d a i l y g a i n and l i v e r could r e s u l t from greater feed consumption i n the f a s t e r growing p i g . The l i v e r would increase i n s i z e as i t s a c t i v i t i e s , i n c l u d i n g deam-i n a t i o n , transamination, formation and storage of glycogen and d e t o x i f i c a t i o n , increased. I t may be a l s o that the p i g w i t h the l a r g e r l i v e r i s b e t t e r able to handle ingested n u t r i e n t s and thus grows f a s t e r . The strong p o s i t i v e c o r r e l a t i o n s between d a i l y g a i n and small i n t e s t i n e and d a i l y g a i n and l a r g e i n t e s t i n e may i n d i c a t e that pigs which have l a r g e i n t e s t i n a l t r a c t s can handle feed more e f f i c i e n t l y and g a i n f a s t e r . I t may be a l s o t h a t the f a s t -er g a i n i n g p i g eats more feed and the i n t e s t i n a l t r a c t enlarges to supply the e x t r a d i g e s t i v e c a p a c i t y r e q u i r e d . The negative c o r r e l a t i o n between d a i l y g a i n and adrenals could i n d i c a t e that the p i g which i s more esponsive to outside s t i m u l i gains more s l o w l y . This response to outside s t i m u l i would amplify body processes r e s u l t i n g i n increased use of energy f o r these processes with l e s s remaining f o r growth. The general observation that the more d o c i l e animal tends to g a i n 66 f a s t e r would support t h i s theory. This e x p l a n a t i o n would a l s o apply to the p o s i t i v e c o r r e l a t i o n s between feed per 100 l b s . body g a i n and adrenals a'nd feed per 100 l b s . carcass g a i n and adrenals. The p o s i t i v e c o r r e l a t i o n s between feed per u n i t g a i n and spleen could i n d i c a t e the presence of disease of some minor type which i s a c t i n g on the system of the animal to reduce growth r a t e and p o s s i b l y a f f e c t d i g e s t i v e processes. The r e d u c t i o n i n growth r a t e i s shown a l s o i n the negative c o r r e l a t i o n s between d a i l y g a i n and spleen i n groups A and B. Ahronhe.im (1937) has demonstrated that disease c o n d i t i o n s , both chronic and acute, can i n f l u e n c e spleen s i z e . The p o s i t i v e c o r r e l a t i o n s between feed per u n i t g a i n and adrenals could be a r e s u l t of the animals response to e x t e r n a l s t i m u l i . This may r e s u l t i n greater feed consumption per u n i t g a i n through r e d u c t i o n i n r a t e of g a i n as discussed e a r l i e r i n t h i s s e c t i o n , or through some e f f e c t on the d i g e s t i v e organs. This l a t t e r p o i n t would be supported by the s i g n i f i c a n t negative c o r r e l a t i o n between small i n t e s t i n e and adrenals obtained i n the present study. The strong negative c o r r e l a t i o n s of dres s i n g percentage w i t h l i v e r , stomach, small i n t e s t i n e and l a r g e i n t e s t i n e indicate that the s i z e of these organs i n f l u e n c e s dressing percentage to a l a r g e degree. Since these are the l a r g e s t v i s c e r a l organs t h i s r e l a t i o n s h i p i s automatic. P o s i t i v e c o r r e l a t i o n s obtained between percent l e a n cuts and heart could suggest that the more a c t i v e p i g produces a 67 lean e r carcass. That a c t i v i t y has a strong i n f l u e n c e on heart s i z e has been shown by Joseph (1908), Eaton (1958) and Latimer (1947). Another f a c t o r i n f l u e n c i n g t h i s r e l a t i o n s h i p could be s t r e s s c o n d i t i o n s which would amplify the heart r a t e . This i n -crease of heart and general organ a c t i v i t y would use up energy from the n u t r i e n t s which would otherwise be used i n the format-i o n of f a t . Therefore the pig which r e a c t s to s t r e s s c o n d i t i o n s would tend to be lean e r . The n e g a t i v e . c o r r e l a t i o n between heart and percent b e l l y may be explained on the same b a s i s s i n c e from observations e a r l i e r i n t h i s study I t would seem that percent b e l l y i s mainly a f f e c t e d by f a t d e p o s i t i o n i n the carcass. The p o s i t i v e c o r r e l a t i o n between percent l e a n cuts and stomach and the negative c o r r e l a t i o n between percent f a t cuts and stomach may a r i s e from the tendency of the f a t t e n i n g p i g to deposit more f a t on the carcass than on the v i s c e r a . The p o s i t -i v e c o r r e l a t i o n of percent b e l l y w i t h small i n t e s t i n e and l a r g e i n t e s t i n e could be explained on the same b a s i s . (c) Between organs. The h i g h l y s i g n i f i c a n t p o s i t i v e c o r r -e l a t i o n between heart and adrenals would be expected since the adrenal s e c r e t i o n , a d r e n a l i n , acts to increase blood flow i n the body and thus increase heart a c t i v i t y . The h i g h p o s i t i v e c o r r e l a t i o n s of l i v e r w i t h stomach, small i n t e s t i n e and l a r g e i n t e s t i n e would be expected since these o r -gans are so i n t i m a t e l y connected w i t h d i g e s t i o n and a s s i m i l a t i o n of ingested n u t r i e n t s . Feed intake t h e r e f o r e would be expected to i n f l u e n c e a l l of these organs s i m i l a r l y . The p o s i t i v e c o r r e l a t i o n between spleen and adrenals may 68 i n d i c a t e a common response to s t r e s s c o n d i t i o n s . The p roduction of a d r e n a l i n under s t r e s s c o n d i t i o n s and the subsequent increase i n blood f l o w could produce greater spleen a c t i v i t y w i t h a r e s -u l t i n g increase i n s i z e . The p o s i t i v e c o r r e l a t i o n s of stomach ?\rith small i n t e s t i n e and l a r g e i n t e s t i n e and of small i n t e s t i n e w i t h l a r g e i n t e s t i n e r e s u l t from the intimate r e l a t i o n s h i p of these organs i n the process of d i g e s t i o n . I t i s i n t e r e s t i n g to note the negative c o r r e l a t i o n of ad-r e n a l s w i t h stomach, small i n t e s t i n e and l a r g e i n t e s t i n e . This may i n d i c a t e a d i r e c t i n f l u e n c e of the adrenal s e c r e t i o n s on d i g e s t i o n . Repeated response of the adrenals to s t r e s s c o n d i t -ions may r e s u l t i n f a i l u r e of the d i g e s t i v e t r a c t , to develop prop e r l y and r e s u l t i n l e s s e f f i c i e n t u t i l i z a t i o n of ingested n u t r i e n t s . This i s supported by the s i g n i f i c a n t p o s i t i v e c o r r -e l a t i o n between adrenals and feed per u n i t g a i n obtained i n t h i s study. 2. C o r r e l a t i o n s between treatments. These c o r r e l a t i o n s are the r e s u l t of treatment e f f e c t s and therefore vary widely between experimental groups. The s i g n i f -i c a n t between treatment c o r r e l a t i o n s w i l l be discussed f o r each experimental group. (a) Group A. The p o s i t i v e c o r r e l a t i o n of percent l e a n . w i t h stomach would r e s u l t from the e f f e c t s of pasture f e e d i n g . The pasture fed hogs had leaner carcasses due to reduced r a t e of g a i n and l a r g e r stomachs p o s s i b l y from eating l a r g e r amounts of f e e d w h i l e at the feeder. 69 The increased l e a n content of the pasture f e d pigs would r e s u l t i n a decrease i n the; percent b e l l y but an increase i n l i v e r to carcass r a t i o . This s i t u a t i o n would cause the negative c o r r e l a t i o n between l i v e r and percent b e l l y . The p o s i t i v e c o r r e l a t i o n s of heart w i t h l i v e r and l i v e r w i t h stomach could r e s u l t from a general increase i n these o r -gans i n the pasture-fed p i g s . This increase could be caused by grea t e r d i g e s t i v e a c t i v i t y i n an attempt to f u r n i s h the additf- „. i o n a l energy needed f o r e x e r c i s e . (b) Group B. The increase i n growth r a t e and i n percent f a t at the 30% pomace l e v e l would cause the negative c o r r e l a t i o n of d a i l y g a i n w i t h percent f a t . Since i t has been sho?i/n that f a t t e r pigs have higher d r e s s -ing percentages and that percent b e l l y i s i n f l u e n c e by f a t dep-o s i t i o n i t seems l i k e l y t h a t the p o s i t i v e c o r r e l a t i o n between dressing percentage and percent b e l l y i s a r e s u l t of the increas-ed fatness of the pigs on "60% pomace. The decrease i n d i g e s t i b i l i t y of the r a t i o n as pomace l e v e l increases could e x p l a i n the p o s i t i v e c o r r e l a t i o n between feed per 100 l b s . carcass g a i n and l a r g e i n t e s t i n e . In the h i g h pomace r a t i o n s the residue a f t e r d i g e s t i o n would be more bulky and would increase the s i z e of the l a r g e i n t e s t i n e . A l s o i n these r a t i o n s the digested n u t r i e n t s per u n i t of feed ingested would be lower, thus more feed- per u n i t g a i n would have to be ingested to meet t i s s u e b u i l d i n g and energy requirements. The p o s i t i v e ; c o r r e l a t i o n of percent f a t cuts w i t h l i v e r would i n d i c a t e that the r a t i o n i s tending to increase both c a r -70 cass fatness and l i v e r weight. This increase i n l i v e r weight could r e s u l t from g r e a t e r storage of glycogen. (c) Group C. Increasing pomace content of the r a t i o n s has increased feed per u n i t g a i n due to reduced d i g e s t i b i l i t y and has decreased dressing percentage due to increased d i g e s t i v e t r a c t and l i v e r s i z e . Thus, i n c r e a s i n g the pomace l e v e l has produced the negative c o r r e l a t i o n s of feed per 100 l b s . body g a i n w i t h dressing percentage and feed per 100 l b s . carcass g a i n w i t h dressing percentage. The p o s i t i v e c o r r e l a t i o n of percent l e a n cuts w i t h l i v e r and the negative c o r r e l a t i o n of percent f a t cuts w i t h l i v e r would a r i s e from the tendency of r a t i o n s c o n t a i n i n g higher l e v e l s of pomace to reduce carcass fatness and increase the r a t i o of v i s c e r a l organs to carcass. This could a l s o e x p l a i n the neg-a t i v e c o r r e l a t i o n between percent b e l l y and heart. 3. Regressions w i t h i n treatments. The p h y s i o l o g i c a l r e l a t i o n s h i p s involved i n these r e g r e s s -ions have been discussed under the c o r r e l a t i o n s w i t h i n t r e a t -ments s e c t i o n . The r e g r e s s i o n s g i v e f u r t h e r i n f o r m a t i o n however i n that they show j u s t how much increase i n an economic', .charact-e r i s t i c can be expected from a gi v e n increase i n organ s i z e . The u n i t s used f o r organs are such t h a t one u n i t w i l l represent an increase of approximately 10% i n the weight of the organ. 4. Regressions between treatments The p h y s i o l o g i c a l r e l a t i o n s h i p s involved have been d i s c u s s -ed e a r l i e r under the c o r r e l a t i o n s between treatments s e c t i o n . As i n these c o r r e l a t i o n s the e f f e c t of treatments should be 71 kept i n mind when considering the r e g r e s s i o n s . 5. A p p l i c a t i o n of r e l a t i o n s h i p s i n swine breeding. S e l e c t i o n i s a major f a c t o r i n improving e f f i c i e n c y and carcass q u a l i t y i n swine. The e f f e c t i v e n e s s of t h i s s e l e c t i o n depends upon the c h a r a c t e r i s t i c s included i n the s e l e c t i o n index and the h e r i t a b i l i t y of these c h a r a c t e r i s t i c s . The r e l a t i o n -ships determined i n t h i s study have no value i n assessing h e r i -t a b i l i t y . They have some value, however, i n determining which c h a r a c t e r i s t i c s to include i n the s e l e c t i o n index. In determining the c h a r a c t e r i s t i c s to be i n cluded i n the index important c o n s i d e r a t i o n s are: (a) the ease and accuracy of measuring the c h a r a c t e r i s t i c s and (b) the p h y s i o l o g i c a l r e -l a t i o n s h i p s between the c h a r a c t e r i s t i c s . The c h a r a c t e r i s t i c s u t i l i z e d are p r e f e r r a b l y those f o r which measurements can be obtained under ordinary circumstances. The a c t i v i t y of the adrenal glands could be of value i n a s e l e c t i o n index but the d i f f i c u l t y of measuring i t would p r o h i b i t i t s use. "This d i f f i -c u l t y a p p l i e s to most organs and glands. The c h a r a c t e r i s t i c s used are t h e r e f o r e r e s t r i c t e d mainly to those of major economic importance such as d a i l y g a i n , feed per u n i t g a i n , dressing per-cent, and percent l e a n meat i n the carcass. The r e l a t i o n s h i p s g i v e n i n t h i s study show tha t s e l e c t i o n f o r one c h a r a c t e r i s t i c alone may have undesirable e f f e c t s on other c h a r a c t e r i s t i c s . This i s demonstrated by the f o l l o w i n g r e l a t i o n s h i p s : (a) Increased d a i l y g a i n i s accompanied by increased f a t n e s s , 72 (b) Increased l e a n cuts are accompanied by increased feed requirement, (c) Increased b e l l y i s accompanied by increased f a t c u t s , (d) Increased feed e f f i c i e n c y i s accompanied by increased d i g e s t i v e t r a c t weight and decreased dressing percent-age. I t appears from these r e l a t i o n s h i p s t h a t measures of growth r a t e , dressing percentage, l e a n content of the carcass, bacon b e l l y and feed e f f i c i e n c y are d e s i r a b l e i n a s e l e c t i o n index.: f o r swine. I n c l u s i o n of t h i s many c h a r a c t e r i s t i c s w i l l reduce the progress f o r any one of them but should g i v e b e t t e r o v e r a l l improvement toward a more e f f i c i e n t p i g g i v i n g a g r e a t e r per-centage of l e a n meat. 73 V. SUMMARY Development of the market hog was st u d i e d by determination of treatment e f f e c t s on and i n t e r r e l a t i o n s h i p s among, c e r t a i n economic c h a r a c t e r i s t i c s and organ weights. Measurements were taken on 48 pigs from a study of forage u t i l i z a t i o n and s e l f -s e l e c t i o n of p r o t e i n supplement, 24 from a p r e l i m i n a r y t e s t of d r i e d apple pomace u t i l i z a t i o n and 60 from a t e s t of d r i e d apple pomace u t i l i z a t i o n at two l e v e l s of p r o t e i n . Economic character-i s t i c s measured were; d a i l y g a i n , dressing percent, feed per u n i t g a i n and carcass q u a l i t y ( l e a n c u t s , f a t cuts and b e l l y ) . Organ weights taken were; heart, l i v e r , spleen adrenals and d i g e s t i v e t r a c t (cleaned of a l l ingesta and extraneous t i s s u e ) . A l l p igs were purebred Y o r k s h i r e s bred and r a i s e d at the Exper-imental Farm, Agassiz. Treatment e f f e c t s were s t u d i e d by analy-s i s of variance and r e l a t i o n s h i p s by w i t h i n and between t r e a t -ment c o r r e l a t i o n s and r e g r e s s i o n s . Pigs fed i n d r y l o t gained f a s t e r and had f a t t e r carcasses than those on pasture. The pigs on pasture had l a r g e r h e a r t s , spleens and stomachs than those i n d r y l o t . Feeding d r i e d apple pomace at 20% of the r a t i o n by weight had no s i g n i f i c a n t e f f e c t on the c h a r a c t e r i s t i c s measured. A trend to gr e a t e r feed consumption per u n i t g a i n and a heavier l a r g e i n t e s t i n e were noted, however. Increasing pomace to 40% of the r a t i o n reduced r a t e of g a i n , increased feed r e q u i r e d per u n i t g a i n , lowered dressing percent, increased l e a n percent i n the carcass, increased l i v e r weight and increased l a r g e i n t e s t i n e weight. These e f f e c t s were a l l s t a t i s t i c a l l y s i g n i f i c a n t . 74 R e l a t i o n s h i p s among the economic c h a r a c t e r i s t i c s which agree c l o s e l y w i t h those reported by.other workers are: 1. Negative between d a i l y g a i n and feed per u n i t g a i n . 2. P o s i t i v e between dressing percent and percent f a t c u t s . 3. Negative between dressing percent and percent l e a n c u t s . The p o s i t i v e r e l a t i o n s h i p between percent f a t cuts and per-cent b e l l y would i n d i c a t e that b e l l y weight i s determined l a r g e l y by f a t d e p o s i t i o n . The r e l a t i o n s h i p s presented i n t h i s study could be of value i n determining c h a r a c t e r i s t i c s to be included i n a s e l e c t i o n index f o r swine improvement. 75 VI. LITERATURE CITED Addis, T. and Gray, H. 1950. Body s i z e and organ weight. Growth 14: 49-80. - , R.W. Lippman, W. Lew, L . J . Poo, and W. Wong. 1951. 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