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The effects of ration type and ralgro implantation on the growth rate, feed efficiency and carcass composition… Nwokolo, Emmanuel R. N. 1975

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THE EFFECTS OF RATION TYPE AND RALGRO IMPLANTATION ON THE GROWTH RATE, FEED EFFICIENCY AND CARCASS COMPOSITION OF HEREFORD STEERS by Emmanuel R„N..Nwokolo B o S c , University of Ibadan, Nigeria 1972 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN THE DEPARTMENT OF ANIMAL SCIENCE We accept this thesis as conforming to the required standard The University of B r i t i s h Columbia June 1975 In present ing th is thes is in p a r t i a l fu l f i lment of the requirements for an advanced degree at the Un ivers i ty of B r i t i s h Columbia, I agree that the L ibrary sha l l make it f r ee ly ava i l ab le for reference and study. I fur ther agree that permission for extensive copying of th is thes is for s c h o l a r l y purposes may be granted by the Head of my Department or by his representa t ives . It is understood that copying or pub l i ca t ion of th is thes is for f inanc ia l gain sha l l not be allowed without my writ ten pe rm i ss i on . Department of A V M vrw-4 S>U-gy,eg. The Un ivers i ty of B r i t i s h Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date [^Hh ABSTRACT Five r a t i o n types as well as Ralgro implantation were evaluated i n a 5 x 2 f a c t o r i a l experiment to determine th e i r e f f e c t on growth rate, feed e f f i c i e n c y and carcass composition of Hereford steers. The f i v e r a t i o n types were 100% barley, 50% barley-50% a l f a l f a cubes, 100% a l f a l f a cubes, barley followed by cubes, and cubes followed by barley. Implantation of 36 mg Ralgro was done a f t e r 12 weeks on the experi-mental d i e t . The animals were weighed every two weeks, the morning feed being withheld u n t i l weighing had been completed. Rib eye muscle area as well as fat depth over the eye muscle were used to estimate carcass lean and carcass fat. Rib eye area and fat thickness were measured monthly using a USM 2F Krautkramer Ultrasonic flaw detector. The feeding t r i a l s lasted 28 to 36 weeks at the end of which the steers were probed for r i b eye area and f a t depth. They were then starved for 12 hours, weighed and shipped to a packing house. Rib eye muscle area and fat thickness were determined on the c h i l l e d carcasses. Dressing percentage as well as cuta-b i l i t y were also determined on each carcass. The carcasses were then graded. Average d a i l y gain, group feed e f f i c i e n c y and feed cost/kg gain were computed for each r a t i o n type. Results indicated that only the 100%, a l f a l f a r a t i o n supported s i g n i f i c a n t l y lower average d a i l y gain (P< 0.05) than other rations. There were no differences between the r a t i o n types i n terms of the average carcass fat and carcass lean. The 100% barley ration, the 50%, barley r a t i o n as well as the r a t i o n i n which a l f a l f a was followed by barley, a l l gave rise to s i g n i f i c a n t l y higher dressing percentages (P<0.05). Over the ent i r e growth period, implantation of 36 mg Ralgro did not i i i s i g n i f i c a n t l y improve either the growth rate or the carcass composition of the steers so treated. A breakdown of the growth period indicated that within 60 days post implantation, administration of 36 mg Ralgro caused a s i g n i f i c a n t l y higher growth rate than controls. Its e f f e c t , however, disap-peared a f t e r 60 days. There were s i g n i f i c a n t but low p o s i t i v e c o r r e l a t i o n s between the area of r i b eye estimated by the u l t r a s o n i c method just p r i o r to slaughter and that determined on the carcass by acetate paper tracings (r = 0.27) or by the p l a s t i c g r i d method (r = 0.30). There was, however, a very high c o r r e l a t i o n (r = 0.72) between the acetate paper tracings and the p l a s t i c g r i d method of determining the area of r i b eye muscle. Computation of the feed cost/kg gain indicated that at p r e v a i l i n g prices the a l l - b a r l e y r a t i o n was the cheapest to r a i s e steers on while the a l l - a l f a l f a r a t i o n was by far the most expensive. TABLE OF CONTENTS Page ABSTRACT ' • » • • •• i i ACKNOWLEDGMENTS . . . . . . . •. " .. iv TABLE OF CONTENTS v LIST OF TABLES . . . . . . . . . . . . . . . • ix INTRODUCTION . . . . . . . . . . . . 1 LITERATURE REVIEW . . . . . . . . . . . . . . . . . . / 3 Introduction . . . . . . . . . „ . . . . . . 3 Measurements i n l i v e animals . . . . . . . . . . . . 3 The u l t r a s o n i c r e f l e c t i o n techniques i n evaluating carcass composition i n l i v e animals 4 The p r i n c i p l e s . . . . . . . . . . . . . . . 4 Applications . . . . . . . . . . . . . . 5 Estimation of carcass composition based on l i n e a r measurements on the carcass . . . . . 7 (a) Area of longissimus d o r s i muscle ' . . . . . . . . . 7 (b) Composition of r i b j o i n t s . . . . . . . . . . 8 (c) Carcass musculature . . . 9 (d) Fat thickness measurements . . 10 (e) S p e c i f i c gravity measurement . . . . . . . . . . 11 Factors a f f e c t i n g the carcass composition of steers . . . . 12 (a) Age . . . . . . . . . . . . . . . . . 12 (b) Breed 13 (c) Sex . . . . . . . . . . . . . • . . • • 14 E f f e c t of n u t r i t i o n on carcass composition (a) Energy lev e l s . . . . . . . . . . . . . . (b) Protein le v e l s . . . . . . E f f e c t of energy intake on growth and feed e f f i c i e n c y E f f e c t of energy concentration on growth rate and feed e f f i c i e n c y E f f e c t of exogenous hormones and growth stimulation on growth-rate, feed e f f i c i e n c y and carcass composition . . . . E f f e c t of d i e t h y l s t i l b e s t r o l and other growth stimulants on average d a i l y gain and feed e f f i c i e n c y of steers . . . E f f e c t of DES and other growth stimulants on carcass composition E f f e c t of Resorcylic Acid Lactone (Ralgro) on growth rate, feed e f f i c i e n c y and carcass composition of steers . MATERIALS AND METHODS . . . . . . . . . . . . . . . . . . The experimental animals . * •. . The experimental design . . . . . . . . . . . . Hous ing . . . . . . . . . . I n i t i a l management . . . . . . . . . . . . . . . . . Weight procedure . Feeding procedure . . . . . . . Ralgro implantation . . . . „ The experimental treatments . . . . . . . . . Method of estimation of carcass composition by u l t r a s o n i c s D i g e s t i b i l i t y t r i a l s . . . . . . . . . . . . . . Determination of carcass composition at the end of the t r i a l s The a n a l y t i c a l methods . . . . . . . . . . . . T i Page Dry matter determination 31 Nitrogen determination . . . . . . . . . . . „ 31 Acid detergent fibre . . . . . . . . . . . . 32 Ether extract determination . . . :'. . • . . . 32 Gross energy determination . . . . . . . . . . . 32 Treatment of the analytical data . . . . . . . . .. . 33 RESULTS . . . . . . . . . . . . ... . . . . . . 34 Effect of the different rations on growth rate, feed efficiency and carcass composition . . . . 35 (a) Growth rate . . . . . . . 35 (b) Feed efficiency . . . . . . . . . . . . . 36 (c) Carcass composition . . . . . . . . . . . . 39 The effect of implantation of 36 mg Ralgro on growth rate, feed efficiency and carcass composition of Hereford steers . . . 42 (a) Growth rate . . . . .' . . 42 (b) Feed efficiency . . . . . . . 4 4 (c) Carcass composition . 45 Comparison of ultrasonic probe prediction of rib eye area with actual area of rib eye as measured by acetate paper tracings and by the plastic grid method . . . . . . . . . . . . 47 DISCUSSION OF RESULTS . . . . . . . . . . . . . . . . . 49 Effect of the different treatments on growth rate, efficiency of feed u t i l i z a t i o n and carcass composition . . . . . . . 49 (a) Growth rate 49 v i i Page (b) Feed e f f i c i e n c y . . . . . . . . . . . . . 51 (c) Carcass composition . . . . . . . . . . . 52 E f f e c t of Ralgro implantation on growth rate, feed e f f i c i e n c y and carcass composition . . . . . . . . . . . . . 53 (a) Growth rate . . . . . . . . . . . . . . . 53 (b) Feed e f f i c i e n c y . . . . . . . . . . . . „ 53 (c.) Carcass composition „ . . . . . . . 54 Feed costs per kilogram weight gain . . . . . . . . . 54 Comparison of r i b eye area as predicted by the u l t r a s o n i c probe and area of r i b eye as measured on the carcass . . . . . 56 SUMMARY AND GENERAL CONCLUSIONS . . . . . . . . . . . / 59 APPENDIX . ' o . . . . . . . . . . . . . . . . . . - 62 BIBLIOGRAPHY . . . . . . . . . ... . . . . . . . . . . 64 v i i i LIST OF TABLES Page Table 1: A proximate a n a l y s i s of samples of feed m a t e r i a l (DM b a s i s ) . .. . . ... . . . . . . . . . . 34 Table 2: Energy value of feed i n g r e d i e n t s (k cals/g) (DM basis) . 34 Table 3: D i g e s t i b i l i t y c o e f f i c i e n t s of some of the r a t i o n s used i n the experiment . . . . . . . . . . . . . 3 5 Table 4: Average growth r a t e of stee r s on the d i f f e r e n t r a t i o n treatments . . ... . . . . . . . . . . 35 Table 5: Group feed e f f i c i e n c y of Hereford st e e r s on the d i f f e r e n t r a t i o n treatments over v a r y i n g periods of growth (kg feed/ kg gain) . . . . . . . . . . . . . . . . 36 Table 6: Group feed e f f i c i e n c y of Hereford steers on the d i f f e r e n t r a t i o n treatments over v a r y i n g growth periods (M c a l s ME/kg gain) . . . . . . . . . . . . . . • . 3 9 Table 7: E f f e c t of the d i f f e r e n t r a t i o n s on carcass components . 41 Table 8: E f f e c t of r a t i o n treatments on d r e s s i n g percentage and c u t a b i l i t y of s t e e r carcasses . . . . . . . . . . 41 Table 9: E f f e c t of sw i t c h i n g r a t i o n s on group feed e f f i c i e n c y . 42 Table 10: E f f e c t of Ralgro i m p l a n t a t i o n on growth r a t e and carcass composition . . . . . . . . . . . • 43 Table 11: Body weight changes w i t h i n 60 days post i m p l a n t a t i o n of Ralgro . . . . . . . . . . . . . . . . . . . . . 44 Table 12: E f f e c t of Ralgro i m p l a n t a t i o n on group feed e f f i c i e n c y of Hereford steers (kg feed/kg gain) . . . . . . 44 Table 13: Cost of feed i n g r e d i e n t s . . . . ... . . . . 4 5 Table 14: Feed cost per ki l o g r a m weight gain i n Hereford steers . 47 Table 15: C o r r e l a t i o n a n a l y s i s of r i b eye area as determined by (a) the u l t r a s o n i c probe, (b) planimeter measure-ment of acetate paper t r a c i n g s , (c) the p l a s t i c g r i d method . „ . . . . . . . . . . . . Table 16: Comparison of u l t r a s o n i c and carcass measurements of r i b eye area from the l i t e r a t u r e Table 17: Summary of r e s u l t s on r a t i o n treatment ix Page 43 57 61 ACKNOWLEDGMENTS I wish to express my sincere gratitude to Dr. W.D. K i t t s , Chairman of the Department of Animal Science, who suggested the topic to me and made i t a l l possible as well as to Dr. R.M. Tait , my super-v i s o r who guided me through a l l stages of this work. I must also thank Dr. J.A. Shelford for his invaluable assistance at a l l stages. F i n a l l y , my thanks go to the s t a f f of the Beef-Unit for their, cooperation. May, 1975. E. Nwokolo 1 INTRODUCTION E a r l y work by researchers, notably Preston and coworkers (1963, 1970) had i n d i c a t e d that beef c a t t l e could be r a i s e d s u c c e s s f u l l y on a l l - c o n c e n -t r a t e r a t i o n s i f the minimum but adequate l e v e l of roughages were inco r -porated i n t o the r a t i o n . W i t h i n the l a s t decade, a tremendous amount of research work has been done to show that up to a c e r t a i n l i m i t ( u s u a l l y 80-90%), as the l e v e l of concentrate i n the d i e t of ruminants increased, so di d growth r a t e and feed e f f i c i e n c y . With the current i n f l a t i o n a r y trends of the world economy, the p r i c e of grains has r i s e n so s t e e p l y that farmers are once again c o n s i d e r i n g t u r n i n g to a l l - f o r a g e d i e t s or at l e a s t to forage-grain combinations. One of the o b j e c t i v e s of t h i s study was to determine the e f f e c t on growth r a t e , feed e f f i c i e n c y and'carcass composition, of r a t i o n s which v a r i e d from a l l -hay through h a l f - h a y - h a l f - g r a i n to a l l - g r a i n . The e f f e c t of r a i s i n g steers on hay and f i n i s h i n g on g r a i n as w e l l as r a i s i n g them on g r a i n and f i n i s h i n g on hay was a l s o studied. This study a l s o involved the determination of the t o t a l feed costs per u n i t of l i v e weight gain for animals ort the d i f f e r e n t d i e t s . I t was therefore designed to show i f at such high costs of g r a i n s , the feed cost per u n i t of gain would be so p r o h i b i t i v e as to j u s t i f y the use of forages. Ever s i n c e a ban was placed i n Canada on the use of d i e t h y l s t i l b e s -t r o l as an anabolic hormone i n animals for fear that i t i s c a r c i n o g e n i c , i n c r e a s i n g use has been made of R e s o r c y l i c A c i d Lactone (Ralgro) as an a l t e r n a t i v e growth stimulant. This study was a l s o designed to compare the e f f e c t s of i m p l a n t a t i o n of Ralgro on the growth r a t e , feed e f f i c i e n c y and carcass composition of Hereford s t e e r s . A f i n a l a s p e c t o f t h i s s t u d y i n v o l v e d a c o m p a r i s o n o f d a t a on c a r c a s s c o m p o s i t i o n o b t a i n e d by u l t r a s o n i c r e f l e c t i o n methods i n t h e l i v e a n i m a l w i t h d a t a on t h e same c h a r a c t e r i s t i c s o b t a i n e d from t h e c a r c a s s a f t e r s l a u g h t e r . The q u e s t i o n t h a t p l a g u e s most u s e r s o f the u l t r a s o n i c method i s t h a t o f t h e r e l i a b i l i t y o f t h e d a t a o b t a i n e d , and t h e i r c o m p a r a b i l i t y w i t h f i g u r e s o b t a i n e d by measurements on t h e c h i l l e d c a r c a s s . Towards t h a t end, t h i s s t u d y was s e t up t o d e t e r m i n e the p r e d i c t a b i l i t y o f c a r c a s s c h a r a c t e r i s t i c s from l i v e probe d a t a . LITERATURE REVIEW Introduction . This review of the l i t e r a t u r e aims to spot l i g h t published r e s u l t s on various aspects, of estimation of carcass composition, including measure-ments on the l i v e animal as well as measurements on sample joints,, muscle area, carcass fat and s p e c i f i c gravity as estimators of carcass composition. Some of the factors a f f e c t i n g carcass composition of animals are also d i s -cussed. The ef f e c t s of energy intake, energy concentration and exogenous hormones on growth rate, feed e f f i c i e n c y and carcass composition are reviewed. Measurements i n l i v e animals Many workers have attempted to co r r e l a t e measurements in the l i v e animal with carcass composition. Good et. c Q . (1961) /using 674 steers representing three breeds of c a t t l e reported that width between the eyes, width of muzzle, circumference of round and circumference of cannon bone were s i g n i f i c a n t l y and negatively correlated with the fat cover at the 12th r i b . Orme e_t a l . (1959 ) showed the existence of r e l a t i v e l y high c o r r e l a -tions (r = 0.43 to 0.80) between measurements i n l i v e animals and related carcass c h a r a c t e r i s t i c s . However, Woodward. e_t a_l. (1959) as well as Bass et. a_l. (1962) did not consider l i n e a r measurements as being of much pre-d i c t i v e value i n estimating carcass composition. Other body measurements used by various workers to predict carcass q u a l i t y in beef c a t t l e include the rat i o s of weight to height, weight to length ( T a l l i s et. al_, 1959), r a t i o of chest g i r t h to wither height (Preston et a l . 1963 ). Photogrammetry, a technique for determining body volume from photo-graphs has a l s o been t r i e d . Brinks et a_l. (1964 )'. used i t to p r e d i c t s u c c e s s f u l l y the carcass q u a l i t y of Hereford but not Brown Swiss s t e e r s . Other methods of e s t i m a t i o n of carcass composition on the l i v e animal i n -clude f a t probing u s i n g a hypodermic thermister needle (Warren ejt al_. 1959, Brackelsberg et a l . 1967); s k i n f o l d measurements ( T u l l o h 1961); measurement of body water w i t h a n t i p y r i n e dye (Garret e_t a_l. 1959a); use of t r i t i a t e d water (Panaretto and T i l l 1963); e s t i m a t i o n by means of r a d i o a c t i v e Potassium-40 ( K i r t o n 0 a n d Pearson 1963); and use of muscle biop s i e s from the t e s t animals ( E V e r i t t 1964a). An important method of e s t i m a t i n g carcass composition i n l i v e animals involves the use of the u l t r a s o n i c r e f l e c t i o n techniques. The u l t r a s o n i c r e f l e c t i o n techniques i n e v a l u a t i n g carcass composition i n  l i v e animals The P r i n c i p l e s : Very high frequency sound transmitted as u l t r a s o n i c waves provides a method for the non-destructive t e s t i n g of m a t e r i a l s . U l t r a s o n i c waves are transmitted i n s t r a i g h t l i n e s through s o l i d o b j e c t s . In the u l t r a s o n i c determination of body components, use i s made of the u l t r a s o n i c ' energy which i s r e f l e c t e d from the lower l i m i t of the t i s s u e . I t i s the p r a c t i c e using short pulses sent out r e g u l a r l y , to measure not only the i n t e n s i t y of the echo but a l s o the time i t takes to t r a v e l from the t r a n s m i t t e r to the back-w a l l of the t i s s u e and r e t u r n to the r e c e i v e r . These pulses t r a v e l through any t i s s u e i n the animal's body with a speed c h a r a c t e r i s t i c of that p a r t i -c u l a r t i s s u e . The time r e q u i r e d to t r a v e r s e the t i s s u e is' p r o p o r t i o n a l . t o the depth of the t i s s u e . U s u a l l y the equipment i s c a l i b r a t e d i n m i l l i m e t e r s or centimeters when body components are being measured. A cathode ray tube not only indicates the transmitted impulses and r e f l e c t e d echoes but also measures the i r times of t r a v e l i n the tissues of the body. The transmission pulse and subsequent echoes appear as peaks r i s i n g out of a bright zero l i n e on the fluorescent screen of the cathode ray tube. The distance between the impulse peak and the echo peak is a measure of the time of tra v e l through the material and can be c a l i b r a t e d to give the depth of the material. Transmission of the impulse involves the use of a f l a t quartz c r y s t a l which vibrates mechanically when a s u i t a b l e high frequency voltage is applied to i t . Since the impulse cannot be transmitted through a i r , use is made of a layer of o i l or water on the surface of the specimen. Usually motor grade o i l is used.. When an u l t r a s o n i c wave st r i k e s a quartz c r y s t a l , an e l e c t r i c voltage^ is generated i n i t and the c r y s t a l acts as an u l t r a -sonic receiver. Therefore, a returning u l t r a s o n i c echo may s t r i k e the same quartz c r y s t a l that sent out the impulse and hence that quartz c r y s t a l acts as both a transmitter and a receiver. In practice, the same c r y s t a l is used both as a transmitter and a receiver i n continuous rapid a l t e r n a t i o n . Accurate transmission and reception of impulses requires some degree of surface preparation. Hence, when hairy animals are being probed, i t becomes necessary to c l i p the hair as close a's possible. The choice of frequency is determined by the density or permeability of the material. Transmission and reception are better at low frequency and clear echoes are obtained. Usually for determination of fat depth, low frequencies are used, while for determination of muscle depth higher frequencies may be needed. Applications: Ever since the mid 1950's the p r a c t i c a b i l i t y of measuring the depth of fat and lean tissues i n l i v e animals by ult r a s o n i c probing techniques has received considerable attention. Temple et a l , (1956) repo'rted that an u l t r a s o n i c device c a l l e d the "somascope" provided a f a i r l y good measure of fat thickness i n l i v e c a t t l e . Laupretch e t a l , (1957) su c c e s s f u l l y applied u l t r a s o n i c techniques to measure fat thickness i n l i v e pigs and hog carcasses. Since that time, the use of u l t r a s o n i c devices to predict carcass composition has been established i n pigs (Panier 1957, Hazel and Kline 1959, Urban and Hazel 1965); i n c a t t l e (Stouffer et al_. 1961, Hedrick et a l . 1962, Alsmeyer et_ a_l. 1963, Davis et a_l. 1964 and 1965, McReynolds and Arthaud 1970); and in sheep (Campbell et a l . 1959, Moody et a l . 1965). This technique has been reported to be quite s a t i s f a c t o r y by many research workers. They showed that r e l i a b l e estimates of fat thickness and longissimus d o r s i muscle areas could be made. High cor r e l a t i o n s between u l t r a s o n i c determinations of fat and longissimus muscle depth and measurements of these c h a r a c t e r i s t i c s on the carcass have been reported by Price e_t a_l. (1960a, 1960b); Davis and Long (1962); Davis, et a l . (1964); Watkins et a l . (1967); McReynolds and Arthaud (1970). The u l t r a s o n i c technique has also been used to study fat and muscle deposition rates i n animals (Urban and Hazel 1960, F i e l d and Schoonover 1967). From t h e i r study of rates of fat deposition and longissimus muscle growth, McReynolds and Arthaud (1970) showed that a c u r v i l i n e a r r e l a t i o n s h i p existed between l i v e weight and fat deposition and that the r e l a t i o n s h i p between, l i v e weight and longissimus d o r s i muscle.growth•was l i n e a r . Estimation of carcass composition based on l i n e a r measurements on the  carcass Yeates (1952) proposed a method of incorporating simple measurements on the carcass into an objective system for appraising carcass composition,, The method involved the expression Of carcass weight as a function of car-cass length with a c o r r e c t i o n for fat thickness. However, since this method was proposed, various workers (Bodwell e_t a l . 1959, ; and Martin. 1968) have clearly.demonstrated i t s inadequacy. Dumont et a l . (1961 ) from a study of 29 Charolais steers proposed an equation which would predict carcass muscle from measurements of h a l f carcass weight, . thickness of thigh and weight of diaphragm. Ramsey e_t a l . (1966) in a study of 130 steers of seven breeds concluded that, only a few l i n e a r charac-ters could be related to separable muscle weight, the characters being chest circumference (r = 0.53) round circumference (r =0.50) and carcass length (r 0.42). (a) Area of longissimus d o r s i muscle: . The cross-sectional area of the longissimus d o r s i muscle has been frequently considered as an index of muscling i n carcasses. Henderson et  a l . (1966c) have reported the use of fat thickness and.the longissimus d o r s i area per 50 kg carcass weight.as variables in an equation to predict car-cass lean. The longissimus d o r s i area may be accurately measured from a t r a c i n g on acetate paper and by using a compensating polar planimeter (Naumann 1952, Bodwell .et.al. 1959 ); by superimposing a g r i d d i r e c t l y over the eye muscle and counting the squares (Riley e_t a l . 1966, H i l l e r s et a l . 1968); by photographic methods as outlined by Schoonover and Stratton (1957) and modified by Corbin et a l . (1959). This l a t t e r method involves taking o transparencies and trac i n g the areas of the longissimus d o r s i with a com-pensating planimeter. .. . The cr o s s - s e c t i o n a l area of the longissimus d o r s i muscle ( r i b eye) has been correlated to various measures of carcass leanness. There is a tremendous amount of v a r i a t i o n i n c o r r e l a t i o n c o e f f i c i e n t s reported between carcass weight and r i b eye area (0.12 to 0.81) by W i l l i s et a_l. (1968) and F i e l d and Schoonover (1967) respectively. Correlations between r i b eye area and per cent e d i b L e meat range from r = 0.02 ( W i l l i s et a l 1968) to r = 0.82 (Mil Ler e_t al. 1965) while poor cor r e l a t i o n s have been demon-strated to e x i s t between r i b eye area and per cent separable lean (Cole et a l . 1960, Henderson et a l . 1966b)„ (b) Composition of r i b -joints: Hankins et a_l. (1943) and Hankins and Howe (1946) were the f i r s t to point out that c e r t a i n constituents of the 9-10-1.1th r i b cut of steer car-casses were very c l o s e l y r e l a t e d to the corresponding constituents of the dressed beef carcass. When the per Cent separable lean, fat and bone of the 9-10-llth r i b were correlated to the per cent separable dressed carcass lean, fat and bone, correlations of 0.90, 0.93 and 0.80 respectively were obtained. Correlations of 0.94, 0.97 and 0.73 respectively were obtained by Crown and Damon (1960) for these same carcass components. Tliese workers also ob-tained c o r r e l a t i o n c o e f f i c i e n t s of 0.82, 0.96 and 0.75 respectively between the per cent separable lean, fat and bone of the 12th r i b cut arid the dressed carcass. They therefore suggested that the separable constituents of either the 12th r i b cut o r the 9-10-llth r i b cut may be used, to predict carcass composition. ' Branaman e_t al_„ (1962) also showed that the percentage ether extract i n the 9-10-llth r i b cut was highly negatively correlated (r = -0.87) 9 with carcass separable lean. Cole e_t a l . (1962) re-evaluated the equation of Hank ins and Howe (1946). Per cent lean i n carcass = 16.08 + 0.80 (7a lean i n 9-10-llth r i b ) by comparing i t s predicted value of carcass lean with actual separable lean i n 81 carcasses. They obtained very high c o r r e l a t i o n c o e f f i c i e n t s (r = 0.95). between predicted and actual values. (c) Carcass musculature: Joubert (1956) i n studies of factors influencing the post natal growth and development of muscle f i b r e and on the r e l a t i o n s h i p between muscle f i b r e diameter and body siz e i n the new born lamb, demonstrated the existence of a close r e l a t i o n s h i p between muscle f i b r e diameter and t o t a l musculature In lambs. He thus drew attention to the p o s s i b i l i t y of using muscle f i b r e diameter as an indicator of carcass composition i n sheep. Tuma et a l , (1962a) reported a c o r r e l a t i o n c o e f f i c i e n t of 0.82 between muscle f i b r e diameter of the longissimus d o r s i and t o t a l carcass muscula-ture as estimated by the 9-10-llth r i b separation. This c o r r e l a t i o n was, however, age dependent and these workers concluded that muscle f i b r e diameter was not a good indicator of t o t a l carcass lean. . It was proposed by Orme et a l . (1960) and B u t t e r f i e l d (1962) that weight of carcass lean was c l o s e l y r e l a t e d to the dissected weight of ce r t a i n muscles. B u t t e r f i e l d (1962) obtained c o r r e l a t i o n c o e f f i c i e n t s (r = 0.99) between t o t a l weight of muscle and the following dissected muscles; biceps femoris, semi membranosus, adductor femoris and longissimus d o r s i . He therefore concluded that weights of in d i v i d u a l muscles might be a better index of carcass lean than r i b cuts. (d) Fat thickness measurements: Murphey et a_l. (1960) used both the average fat thickness over the r i b eye muscle and the kidney f a t i n an equation to predict the percentage of f i r s t q u a l i t y meat in beef. This equation subsequently formed the basis of the U.S.D.A. y i e l d grade which was introduced to accompany carcass grad-ing i n the s o - c a l l e d dual grading system. The use of both fat thickness and kidney fat has been supported by Abraham et a l . (1968) who showed that both fat thickness over the r i b eye and the kidney f a t were highly corre-lated with weight and per cent boneless steak and roast meat. Fat thickness alone accounted for more of the v a r i a t i o n i n per cent boneless steak and roast meat than any other si n g l e v a r i a b l e . I t was also shown by Ramsey e_t aJL. (1962) that fat thickness over the r i b eye was as good an indicator of carcass lean as carcass or y i e l d grade. Fat thickness over the r i b eye has been correlated to various car-cass c h a r a c t e r i s t i c s . A low c o r r e l a t i o n c o e f f i c i e n t (r = 0.22) was obtained by Wilson et a l . (1964) between fat thickness over the r i b eye and carcass weight. These workers reported a c o r r e l a t i o n of r = 0.53 between fat thick-ness and carcass grades while Abraham e_t 'al. (1968) reported a c o r r e l a t i o n of r = 0.60. Correlations ranging from 0.65 to 0.90 were reported by Brungardt and Bray (1963) and B u t t e r f i e l d (1964 ) re s p e c t i v e l y between fat thickness over the r i b eye muscle and per cent carcass fat. These high c o r r e l a t i o n c o e f f i c i e n t s are i n d i c a t i v e of the p r e d i c t i v e nature of measure-ments of fat thickness over the r i b eye muscle. Per cent carcass fat is inversely r e l a t e d to the carcass lean, hence, i t should be expected that fat thickness measurements' would be negatively co r r e l a t e d to measurements of carcass lean. Negative c o r r e l a t i o n c o e f f i c i e n t s ranging from -0.67 ( F i e l d et a l . 1966 ) to -0.83 ( B u t t e r f i e l d et a_l. 1964 ) have been reported for fat . 1 1 ' thickness and per cent carcass muscle. Many workers have also correlated fat thickness _over the eye muscle with per cent edible meat and co r r e l a t i o n s ranging from -0.64 (Allen e_t a l . 1968) to -0.87 (Riley et a l . 1968) have been reported. (e) S p e c i f i c g r a v i l y measurement: S p e c i f i c gravity determinations have been shown to be c l o s e l y asso-c i a t e d with the fat content of the eviscerated guinea pig carcass (Rathbun and Pace 1945); with the degree of obesity i n the human body (Boyd 1933); with the fat content of the pork carcass (Brown ejt a l . 1951); with the leanness of pork carcass (Price et a_l. 1957) ; and with the f a t and lean c a t t l e (Meyer et al_. 1960). In the method used for hogs and c a t t l e , hydrostatic weighing was used to determine the s p e c i f i c the carcass. Each h a l f of the carcass was weighed in a i r to the grams, then submerged i n water and weighed to the nearest .1 l b . xne weignts of the two halves were added to obtain the weight of the entire carcass. .The formula Wt. i n a i r = s p e c i f i c gravity Wt. i n a i r - Wt. i n water was used to c a l c u l a t e the s p e c i f i c gravity of the carcass. S p e c i f i c gravity measurements have been claimed by Brown e_t a l . (1951) to be as e f f e c t i v e as per cent fat and lean cuts in estimating carcass composition. These workers obtained c o r r e l a t i o n c o e f f i c i e n t s of -0.95 between s p e c i f i c gravity and per cent ether extract and 0.95 between s p e c i f i c gravity and per cent protein in the carcass. Meyer et a l . (1960b) developed an equation Y = 487.5 - 439.8X content of applied to gravity of nearest 50 1 2 where Y = carcass fat in per cent X --. s p e c i f i c gravity of the carcass to predict carcass fat from the s p e c i f i c g r a v i t y measurements. The corre-l a t i o n c o e f f i c i e n t between the s p e c i f i c gravity of the dressed carcass and the per cent carcass fat was r = -0.98. The per cent fat i n the 9-10-llth r i b j o i n t was found to be f a i r l y highly correlated with the s p e c i f i c gravity of this j o i n t . C o r r e l a t i o n c o e f f i c i e n t s varied from r = -0.40 (Cole et. a l . I960) to r = -0.73 (Kropf 1959). F a i r l y high p o s i t i v e c o r r e l a t i o n c o e f f i c i e n t s were also reported by both Kropf (1959) and Cole et. a_l. (1960) between the s p e c i f i c g r a v i t y of the 9-10-llth r i b j o i n t and the per cent separable lean i n the r i b j o i n t . Confirming an e a r l i e r observation by Brown .et a l . (1951), Cobb and Ovejera (1965) obtained a p o s i t i v e c o r r e l a t i o n c o e f f i c i e n t of 0.72 between the s p e c i f i c gravity of the carcass and the per cent edible meat of the car-cass. They also reported a c o r r e l a t i o n c o e f f i c i e n t of 0.74 between car-cass s p e c i f i c gravity and per cent f i r s t q u a l ity meat in the carcass. Factors a f f e c t i n g the carcass composition of steers (a) Age : A great deal of v a r i a t i o n has been shown to exist among carcasses' and carcass c h a r a c t e r i s t i c s when these are examined at various ages. Hammond and Appleton (1932) and McMeekan (1940a,b) reported that muscle f i b r e s i z e increased s i g n i f i c a n t l y with age. Joubert (1956) obtained a c o r r e l a t i o n of r = 0.75 between muscle f i b r e s i z e and age i n lambs. The greatest changes were reported to occur early i n l i f e , the r e l a t i v e growth diminishing thereafter. McMeekan (1940b) observed that the intramuscular fat content of pigs increased with age up to 28 weeks of age. Tuma e_t a l . (1963) using the composition of the longissimus d o r s i muscle as representa-t i v e of the carcass, obtained no s i g n i f i c a n t difference i n protein and ash content with age but a s i g n i f i c a n t difference with regard to moisture content was reported. Fat content was also shown to increase with age. They also reported fat thickness over the eye muscle as being highly pre-d i c t i v e of carcass fat. In another study Tuma e_t a_l. (1962b) reported a s i g n i f i c a n t decrease i n the tenderness of the longissimus d o r s i steaks with advancing age and suggested that the c r i t i c a l age for tenderness i n beef may f a l l i n the range of 18 to 20 months. (b) Breed: The carcass composition of an animal is influenced to a great extent by breed (Kauffman e_t al_. 1968). Damon e_t a_l.. (1960) working with 275 steers from 4 purebred and 20 crossbred groups reported that steers incorporating genes from Angus, Hereford, or Shorthorn breeds resulted in higher grades than steers of Brahman, Brangus or Charolais breeds. They showed that steers s i r e d by Charolais b u l l s had s i g n i f i c a n t l y higher percentage of lean meat and less fat than did. steers s i r e d by any other breed. Damon and coworkers confirme the work of Black e_t a_l. (1934) who had e a r l i e r reported that Brahman cross breds contained s l i g h t l y less fat than Herefords and Shorthorn. Collabora-t i v e evidence for these conclusions has also been found i n the published re s u l t s of Abraham et a l . (1968) and Kauffman et a l . (1968). Kidwell and McCormick (1950) from an analysis of the 9-10-llth r i b -jo i n t s of Holstein and Hereford carcasses concluded that Holsteins had more muscle and bone and less fat than Herefords, Callow (1961) from a t o t a l analysis of carcasses of these breeds reported only the muscle tis s u e as being more in the Holsteins. (c) Sex: Several workers have demonstrated that the sex of an animal exerts a profound e f f e c t on i t s carcass composition. Arthaud e_t a l . (1969) reported that at the same age, b u l l s weighed s i g n i f i c a n t l y more than steers and the i r carcasses yielded more boneless trimmed r e t a i l product before and a f t e r adjustment to a common carcass weight. Chemical analysis of a 1 cm thick boneless cut at the 12th r i b indicated that bulls had 11% less fat and 11%,' more.- protein than comparable steer cuts. At the same carcass weight, bulls have been shown to have s i g n i f i -cantly higher percentage lean and lower percentage fat than steers, whether the method of determination is by the 9-10-llth r i b separation (Raven et a l . 1966) or by s p e c i f i c gravity determination (Bailey e_t al_. 1966 ). In a l l these r e s u l t s , bulls had a c o n s i s t e n t l y higher percentage bone in the carcass. King e_t a_l_. (1964) showed that b u l l carcasses are s i g n i f i c a n t l y d i f f e r e n t from both steers and h e i f e r s in having larger r i b eye areas, less fat thickness and t o t a l fat trim, more t o t a l boneless c l o s e l y trimmed l o i n , r i b , round, rump, chuck and boneless chuck. Bradley ejt a_l. (1966) also showed that steers had s i g n i f i c a n t l y higher r i b eye area than h e i f e r s . Steers had less fat thickness over the 12th r i b and higher carcass conformation grade than h e i f e r s . P hysical separation of the 9-10-l l t h r i b section revealed that h e i f e r s had more fat and less lean than .steers. E f f e c t of n u t r i t i o n on carcass composition were (a) Energy l e v e l s : Swan and Lamming (1967) fed replaced by increasing l e v e l s isonitrogenous rations of ground straw. They i n which cereals showed that per-15 centage bone and carcass waste were p o s i t i v e l y r e l a t e d to the proportion of straw i n the r a t i o n while per cent kidney fat, per cent carcass fat and weight of carcass fat were negatively related to the dietary straw l e v e l . Similar r e s u l t s were reported by Martin e_t a_l. (1966 ) who observed that increasing the cereal content increased the carcass fat but not carcass lean in absolute terms. Reducing the energy intake of steers has s i m i l a r l y been shown to depress fat- deposition (Lamming e_t al_. 1966). Waldman et a l . (1971) observed that either feeding high energy rations to weaning (91 kg) followed by medium energy rations to 590 kg or feeding medium energy rations to 455 kg followed by high energy rations to 590 kg resulted in more muscle tissue than continuously feeding medium energy rations to 590_ kg l i v e weight. These workers reported that during early growth to 227 kg, fat deposition was not influenced by n u t r i t i o n a l treatment. Thereafter, the high energy r a t i o n produced greater amounts of carcass fat than medium energy rations. They showed that when animals- were fed high energy rations, fat deposition was faster than muscle growth while on medium energy rations, the rate of fat deposition was analogous to the rate of muscle growth. (b) P r o t e i n l e v e l s : The r e s u l t s of work on the e f f e c t of d i f f e r e n t protein l e v e l s on carcass composition seem c o n f l i c t i n g . Kay et a_l. (1968) reported that although there were no s i g n i f i c a n t differences between steer groups receiv-ing 11.0%, 14.2%, or 16.98%, crude protein, there was a suggestion that the fat content was higher and the water content lower i n the steers on the 16.93%, protein diet as compared to those on the 11.0% protein d i e t . On the other hand, Morris (1966) had indicated that the a d d i t i o n of urea to low protein diets s i g n i f i c a n t l y decreased the fat trimmings from the hind-quarters of such steers. Wellington et a l . (1954) as well as Guenther et a l . (1962, 1965) reported that improved dressing percentage resulted from increasing dietary le v e l s of protein and energy. A contrary view was, however, held by Winchester et a l . (1957) who observed that increasing the dietary levels of protein and energy had no e f f e c t on the dressing percentage of c a t t l e slaughtered on a weight-and-grade-constant basis. E f f e c t of energy intake on growth and feed e f f i c i e n c y I t i s well established with c a t t l e that under both extensive and intensive animal husbandry, animals which eat more w i l l usually produce more. Voluntary feed intake a f f e c t s not only growth rate but also feed e f f i c i e n c y . . Several theories have been advanced to explain the regulation of voluntary intake. These include: (1) a central nervous control (Brobeck 1955) for which evidence has been adduced to show that appetite is regu-lated by.the balance or i n t e g r a t i o n of s t i m u l i to the ventromedial area of the hypothalamus r e s u l t i n g i n the manifestation or i n h i b i t i o n of appetite; (2) oropharyngeal regulation, for which i t was proposed that fatigue of the jaw muscles (Voisin 1955), rate of eating (Hesselbarth 1954), metering i n the mouth, or p a l a t a b i l i t y could be important c o n t r o l l i n g factors; (3) a thermostatic regulatory mechanism proposed by Brobeck (1948) who suggested that animals ate to keep, warm and stopped eating to prevent hyperthermia; (4) a g l u c o s t a t i c regulation mechanism proposed by Mayer (1955 ) who postu-lated that short term regulatory mechanisms might operate through chemore-ceptors s e n s i t i v e to blood glucose; (5) a l i p o s t a t i c regulation mechanism (Kennedy 1953) i n which the s a t i e t y centre is concerned i n preventing i n -take of surplus energy which would lead to deposition of excess f a t . 17 For beef c a t t l e i n many of the t r o p i c a l countries of the world, some of the r e s t r i c t i o n i n energy intake i s not voluntary. Hence they spend some period of the i r l i f e growing at a rate below optimum, r e l a t i v e to their genetic p o t e n t i a l . This occurs during the f i v e to nine months of the dry season i n those countries and usually corresponds to the period immediately post weaning when feed intake and growth rate should be maxi-mised. Waters (1908) f i r s t noted that an animal that was below the normal s i z e at a given age, through poor nourishment, apparently had the capacity when l i b e r a l l y fed to compensate for this loss i n measure at least by an increased rate of gain. Winchester and Howe (1955) showed that both muscle and s k e l e t a l growth were as rapid as, or more rapid than controls.during ' realimentation. They also showed that such realimentated c a t t l e demons strated high voluntary feed intakes. R e s t r i c t i o n i n energy intake followed by realimentation has also been shown'to cause increased feed e f f i c i e n c y during the period of compensation. Benedict and Ritzman (1927) as well as Hogan (1929) suggested that the improved e f f i c i e n c y could be due to the lower maintenance requirements consequent on small body weight. Reid et' a l . (1955) have shown that during compensatory growth, realimentated animals exhibited an improvement i n energetic e f f i c i e n c y even greater than that manifested for feed conversion rate. The time required for recovery from the r e s t r i c t i o n i n feed intake varied depending on when the r e s t r i c t i o n was imposed and on the l e v e l of realimentation. Winchester and Howe (1955) reported that feed e f f i c i e n c y was not affected. Where slaughter was at the same age, r e s t r i c t e d c a t t l e were l i g h t e r ( C a r r o l l 'et a_l. 1963 , Harte 1967). Where i t was at the same l i v e weight, r e s t r i c t e d animals took longer time (Winchester et a l . 1957) Where l i f e t i m e feed intakes were 18 recorded (Winchester e_t al_. 1957, C a r r o l l et a l , 1964) feed e f f i c i e n c y was shown to be the same for c a t t l e on r e s t r i c t i o n followed by realimentation -i and for controls. • • • E f f e c t of energy concentration on growth rate and feed e f f i c i e n c y Though the use of all-concentrate rations became popular in the 1960's, some e a r l i e r work had been done on the subject i n the preceding two decades. Workers such as Black et al_. (1943) as well as Keith et a 1. (1955) reported only s l i g h t l y better gains when concentrates replaced roughages i n diets for c a t t l e . Previous attempts to r a i s e c a t t l e on a l l -concentrate diets had f a i l e d (McCandish 1923), the reason adduced for these f a i l u r e s being due to a deficiency of vitamin A (Mead and Regan 1931). It was Geurin e_t a l . (1956) who f i r s t reported a successful attempt to r a i s e c a t t l e on a l l concentrate rations of crimped oats and protein supple-ment. This was l a t e r followed by the use of r o l l e d barley and protein supplement (Geurin et aJL. 1959). Geurin and coworkers were successful where others had f a i l e d because i n feeding crimped oats or r o l l e d barley they provided a minimal l e v e l of roughage which was - necessary for optimal functioning of the rumen. Since then, this p r a c t i c e has been adopted i n many countries using a v a r i e t y of energy sources but providing the required l e v e l of roughage. That some roughage is required for optimum growth and e f f i c i e n c y to occur, led to investigations into the optimal l e v e l of roughage compatible with the best growth irate and highest feed e f f i c i e n c y . M i l l e r et_ al.. (1967) reported s i g n i f i c a n t increases i n growth rate and feed e f f i c i e n c y when ground corn and supplement replaced ground . a l f a l f a in rations for H o l s t e i n steers. Richardson e_t a_l. (1961) fed rations . d i f f e r i n g i n concentrate to roughage r a t i o s (83:17, 75:25, 50:50) and observed that though the largest average d a i l y gains were produced by the 83:17 ration, there was no s i g n i f i c a n t difference between.the other two rations. They reported a s l i g h t increase i n feed e f f i c i e n c y as the concen-trate l e v e l rose i n the rat i o n s . McCroskey e_t a_l. (1961) demonstrated higher feed e f f i c i e n c y and average growth, rate for steers r e c e i v i n g a concentrate-roughage r a t i o of 80:20 as compared to those receiving a 20:80 ra t i o n . In a comprehensive study of the ef f e c t of rations of d i f f e r i n g concentrate-roughage r a t i o , Woods and Scholl (1962) fed steers rations of the following, concentrate-roughage r a t i o s (0:100, 5:95, 9:91, 17:83, 25:75, 33:67). They reported a l i n e a r increase i n both average d a i l y gain and feed e f f i c i e n c y as the concentrate i n the r a t i o n was Increased. A s i m i l a r t r i a l was conducted by Bucy and Bennion (1962) who fed 70%, 857„ or 95% concentrate rations to steers. They also reported a l i n e a r increase, i n growth rate and feed e f f i c i e n c y as the l e v e l of concentrate i n the r a t i o n rose. In a second t r i a l , Bucy. and Bennion (1962) showed that an 85%, concen-tr a t e r a t i o n was as good as a 95%, or 100%, concentrate r a t i o n for fattening steers. Interpretation of re s u l t s from these t r i a l s is made d i f f i c u l t by the wide va r i e t y of diets used, the d i f f e r e n t .types and sources of c a t t l e and the d i f f e r e n t concentrate-roughage r a t i o s used. It is possible, however, to e s t a b l i s h broad conclusions. It i s clear that when concentrates c o n t r i -bute up to 85% of the ratio n , there is an improvement i n d a i l y gain and a d e f i n i t e increase i n e f f i c i e n c y of feed u t i l i z a t i o n . zu E f f e c t of exogenous hormones and growth stimulants.on growth rate, feed  e f f i c i e n c y and carcass composition S t i l b e s t r o l and other hormones: . Numerous investigations have shown the growth stimulatory effect, of natural and synthetic hormones when administered to c a t t l e (Dinusson et a l . 1950, Burroughs e_t a_l. 1954, Preston e_t a_l. 1970). The most commonly used hormones have been d i e t h y l s t i l b e s t r o l (DES) and hexosterol. They d i f f e r only s l i g h t l y i n structure and are generally considered to be equally e f f e c t i v e (Perry et a l . 1955). P h y s i o l o g i c a l responses l i k e increased feed, e f f i c i e n c y , raised t a i l heads, slack thighs have been reported (Andrews et a l . 1954). Other hormones which have been investigated i n the hope of discovering an anabolic substance with l i t t l e estrogenic a c t i v i t y include D i a l l y s t i l b e s t r o l (Kercher 1960 ); Diallyhexosterol (Dyer e_t a l . 1960); Dienoestrol (Andrews et a l . 1956); Melengestrol acetate (Bloss et a l . 1966); Oestradiol (Deans et_ al_. 1950) and Testosterone (Beeson et a_l. 1956 ). Almost a l l have shown some degree of improvement in the rate of gain of animals so treated. A more recent trend has been to combine these hormones in d i f f e r e n t proportions to produce growth stimulants. Such compounds include Synovex-H (200 mg testosterone propionate and 20 mg e s t r a d i o l benzoate) for h e i f e r s , Synovex-S (200 mg progesterone and 20 mg e s t r a i o l benzoate) for steers, Rapigain (120 mg testosterone and 24 mg DES). In addition, some growth stimulants which are non-steroid have also been used in l i v e s t o c k production. These include a Resorcylic acid lactone c a l l e d Zeranol and marketed as Ralgro or RAL (36 mg Zeranol). D i e t h y l s t i l b e s t r o l is no longer a v a i l a b l e for use i n animals i n Canada because of the fear that i t is carcinogenic. However, i t i s s t i l l being used in some parts of the world including the United States. Natural 21 steroids, eg. Synovex and other growth compounds l i k e Ralgro which are non-steroid, are, however, a v a i l a b l e for use in Canada. With increasing evidence that these compounds are e f f e c t i v e as growth stimulants, greater use is being made of them. E f f e c t of d i e t h y l s t i l b e s t r o l and .other growth stimulants on average d a i l y  gain and feed e f f i c i e n c y of steers That the administration of DES or other growth stimulants increased the growth rate and feed e f f i c i e n c y of c a t t l e has been reported by many workers (Clegg and C a r r o l l 1957, Woods 1962, Preston and W i l l i s 1970). The mode of administration has no e f f e c t on the phy s i o l o g i c a l response of the animal to the drug (Clegg and C a r r o l l 1957). Lamming (1957, 1958) observed that the degree of response to growth hormones increased with de-creasing n u t r i t i o n a l l e v e l s and showed that hexosterol response was highest under winter feeding conditions,.and lowest i n the spring. Contrary views were, however, held by Webb et_ al_. (1957) and Preston and W i l l i s (1970). Explanations of why and how estrogenic hormones improve growth rate and feed e f f i c i e n c y have been varied. Perry e_t a l . (1955) a t t r i b u t e d i t to improved c e l l u l o s e and nitrogen u t i l i z a t i o n . O g l i v i e et a l . (1960) suggested a prolongation of the growth phase of the fattening steer with the consequent deposition of low c a l o r i e protein and water rather than f a t . As Preston and W i l l i s (1970) summed i t up, the l i t e r a t u r e on the anabolic e f f e c t s of growth hormones is voluminous but the mode of act i o n i s s t i l l imperfectly understood. Administration of exogenous hormones obviously disrupts the balance of natural hormones. It is not, however, c l e a r whether this leads to an increased production of androgens from the adrenals i n an attempt to compensate for added estrogens (Clegg and Cole 1954, Preston et a l . 1960) or the anterior p i t u i t a r y is stimulated to produce more somatotrophins which increase growth rate (Martin and Lamming 1958). E f f e c t of PES and other growth stimulants on carcass composition While It i s almost u n i v e r s a l l y agreed that d i e t h y l s t i l b e s t r o l and other growth stimulants improve the rate of growth and feed e f f i c i e n c y of beef c a t t l e , published r e s u l t s on the e f f e c t of hormones on carcass t r a i t s have varied. Many workers have reported s i g n i f i c a n t differences in carcass composition between DES-treated and untreated steers (Oglivie e_t al_. 1960, Wilson et a_l. 1963), while others have indicated that DES treatment did not s i g n i f i c a n t l y a l t e r carcass composition (Wallentine ejt a l . 1961, Woods 1962). O g l i v i e et al.' (1960) reported that feeding 30 mg/head/day of DES s i g n i f i c a n t l y increased percentage protein and moisture and reduced per-centage fat i n steer carcasses. They postulated that r a t i o n d i g e s t i b i l i t y was not al t e r e d by s t i l b e s t r o l supplementation, that s t i l b e s t r o l prolonged the growth phase of steers fed a fattening r a t i o n . This resulted i n i n -creased deposition of carcass protein and moisture and a delay in deposi-t i o n of fat., This suggestion by O g l i v i e and coworkers is supported by the r e s u l t s of Wilson e_t a l . (1963).. They reported that beef steers implanted with s t i l b e s t r o l were s i g n i f i c a n t l y higher than controls i n estimated per cent carcass lean, and r i b eye area, and s i g n i f i c a n t l y lower in per cent kidney fat. There was, however, no s i g n i f i c a n t difference i n average dressing percentage, per cent carcass fat and bone as well as in estimated per cent boneless r e t a i l cuts or y i e l d grade. Wallentine e_t al_. (1961) reported no differences in r i b eye area., • physical composition, fat cover over the 23 r i b eye, carcass grade and y i e l d between steers implanted or unimplanted with s t i l b e s t r o l . Klosterman e_t al_. (1959) noted that h e i f e r s implanted with, or fed s t i l b e s t r o l showed no s i g n i f i c a n t differences i n carcass composition from controls. Glimp and Cundiff (1971) had also studied the e f f e c t of melengestrol acetate alone or with DES, oh carcass t r a i t s of h e i f e r s . They reported no s i g n i f i c a n t e f f e c t s on carcass c h a r a c t e r i s t i c s . E f f e c t of Resorcylic Acid Lactone (Ralgro) on growth rate, feed e f f i c i e n c y  and carcass composition of steers During 1957 to 1958, signs of hormonal a c t i v i t y were noticed in several herd's • of swine fed mouldy corn. [ ' ' Following that, Resorcylic acid lactone was i s o l a t e d from such corn infected with the fungus G i b e r e l l a Zeae by Stob et. a_l. (1962) who demonstrated that the compound was uterotropic i n castrated female mice and anabolic i n sheep. From this parent compound, over 300 derivatives have been synthesized. Zeranol is a non-steroid chemical compound and is c l a s s i f i e d pharmacologi-c a l l y as a protein anabolic agent. It is a member of the rare class of natural products, the B-resorcylates. I n i t i a l studies had indicated that zetanol, when administered by subcutaneous implant to feedlot steers and lambs, produced an improvement in average daily' gain and feed conversion. Further work revealed that manipulation of the zeranol molecule to a tetrahydro d e r i v a t i v e resulted in an increase i n uterotropic and anabolic a c t i v i t y . These studies also indicated that both forms of Resorcylic acid lactone (RAL) were less u t e r o t r o p i c a l l y a c t i v e than d i e t h y l s t i l b e s t r o l . These investigations were followed by dose-range experiments and f i n a l l y by f i e l d t r i a l s with a large number of beef c a t t l e , veal calves and lambs under d i f f e r e n t management practices and in various geographic locations. 24 Several of these studies indicated that Ralgro implants promoted growth in . livestock (Brown 1970, Perry et a l . 1970).. In most of these studies with c a t t l e , 36 mg Ralgro implants have been used and varied responses have been reported. Workers at the Melfort Research Station, Sask. (1971, 1973) have reported that Ralgro improved the rate of gain of steers.implanted with 36 mg/head. However, when the experi-ments were repeated in 1972, steers showed no response in growth rate. From the i r r e s u l t s i n 1971, these workers reported that implantation with Ralgro, DES or Synovex caused the steers to have a s l i g h t l y less fat cover over the r i b eye muscle and to have a s l i g h t l y larger r i b eye muscle. Brown (1970) reported an extensive test of Ralgro i n ruminants over a 4 year period, involving 24,500 animals and spanning 20 states in the United States. 36 mg Ralgro was administered by subcutaneous implantation i n the ear to c a t t l e and 12 mg to lambs. He observed that with feedlot steers, there was s i g n i f i c a n t l y improved average d a i l y gain and feed e f f i c -iency. With feedlot h e i f e r s , implantation with Ralgro caused a s i g n f i c i a n t improvement i n average d a i l y gain and feed e f f i c i e n c y . Results of implan-t a t i o n of veal calves with Ralgro indicated that there was a 9.07, increase in average d a i l y gain and 6.17, increase in feed e f f i c i e n c y . Perry e_t a l . (1970) compared the e f f e c t s of Ralgro and DES using both fattening and growing rations, both h e i f e r s and steers, both calves and yearlings and reported that Ralgro gave as good a growth response as implanted DES. They also reported that the e f f e c t on growth of Ralgro or DES was greatest i n the early, stages of the t r i a l s and even through the 124th day. They reported that none of the implants affected carcass grade s i g n i f i c a n t l y . Y e a r l i n g steers given a 36 mg Ralgro implant were reported to have given a 137, growth response over the f i r s t 56 days of,a fattening t r i a l . Heavy steers (395 kg) gave a 97, growth response. However, as the t r i a l s progressed, the differences i n growth rate diminished.^ Perry and co workers (1970) suggested that implants might have been depleted towards the end of the t r i a l . They reported that whereas a delayed implant of 36 mg Ralgro at 56 days resulted i n an o v e r a l l 47, non-significant increase in gain, re-implantation with 36 mg Ralgro at 56 days resulted i n an o v e r a l l 87. increase in gain over c a t t l e which were not implanted. 26 MATERIALS AND METHODS The experimental animals F i f t y Hereford steer calves purchased from a livestock auction i n Kamloops, B.C were used i n the experimental t r i a l s . The calves averaged 220 kg l i v e weight and were selected on the basis of uniformity i n weaning weight and conformation. The experimental design The experimental design adopted was a 5 x 2 f a c t o r i a l design i n which f i v e d i f f e r e n t rations were fed to steers implanted or unimplanted with 36 mg Resorcyllc Acid Lactone (Ralgro). The animals were randomly assigned to ten pens, f i v e steers to each pen. The f i v e r a t i o n treatments were re p l i c a t e d . Hous ing Each group of f i v e steers was confined i n a 3.65 x 9.14 metre pen, allowing each animal 6.67 square metres of area. Each pen had an earthen fl o o r bedded with wood shavings, the shavings being added as needed to keep the f l o o r dry. Occasionally a l l old wood shavings were cleared and fresh-bedding added. Feed was provided i n long wooden troughs, water and cobalt-iodized s a l t l i c k s were also provided free choice. I n i t i a l management On a r r i v a l at the Uni v e r s i t y Beef C a t t l e Unit, the experimental animals were fed long g r a s s / a l f a l f a hay and a l i m i t e d quantity of grain. The steers were given in j e c t i o n s of Provite'' (vitamins A, D2 and E) to ''Provite supplied by Ayerst Laboratories, Montreal, P.Q. correct any vitamin deficiency. Reaplex" was also administered to prevent infectious bovine r h i n o t r a c h e i t i s . Ear tags were applied to f a c i l i t a t e i d e n t i f i c a t i o n . Weight procedure The calves were weighed on a r r i v a l at the Beef Unit. Throughout the duration of the experiment, weighing was done at 14 day i n t e r v a l s . As a routine, feed and water were denied the animals u n t i l weighing had been completed. Weighing was started by 8:30 a.m. and was done by d r i v i n g the steers singly through a weigh bridge. Soon a f t e r the i n i t i a l operation, the animals got used to the procedure and it'was done with a minimum of d i s - , turbance. Feeding procedure For 14 days a f t e r a r r i v a l , a l l animals were fed long g r a s s / a l f a l f a hay and barley according to the average l i v e weight of the pen. Thereafter for the next 14 days, steers which would be on a l f a l f a cubes alone for the f i r s t part of the feeding t r i a l s , were gradually put on a l f a l f a cubes. A l l other animals which would be on feed treatments involving either grains alone or grain-forage mixtures, were gradually adjusted to the r a t i o n s which included higher l e v e l s of grains.. A l l animals were on the experimental diets by the 28th day. Animals whose experimental treatment involved feed-ing a l l - g r a i n rations were put i n i t i a l l y on rations containing grains, a l f a l f a cubes and sawdust. The amount of a l f a l f a cubes was gradually de-creased, being withdrawn a f t e r seven days. Sawdust was fed with grains a l l through the experimental period to minimise the incidence of bloat. The Reaplex supplied by Ayerst Laboratories, Montreal, P.Q. 2 8 d a i l y feeding procedure involved feeding twice d a i l y , once i n the morning at 8:30 and again at 3:00 p.m. Throughout the experiment, feed intake was to appetite. Ralgro implantation Af t e r 12 weeks on the experimental d i e t s , h a l f of the steers on each feed treatment group were subcutaneously implanted with 36 mg Resorcylic Acid Lactone (Ralgro). The aim of the implantation was to determine the e f f e c t of the Ralgro on growth rate, feed e f f i c i e n c y and carcass composi-t i o n of the steers. The experimental treatments Five r a t i o n treatments were evaluated i n this experiment. The r a t i o n treatments are presented below. Treatment 1: Treatment 2: Treatment 3: Treatment 4: Treatment 5: Rolled barley + concentrate throughout. Rolled barley + a l f a l f a cubes throughout. A l f a l f a cubes throughout. Rolled barley + concentrate t i l l 340 kg, a l f a l f a cubes t i l l slaughter. A l f a l f a cubes t i l l 340 kg, r o l l e d barley + concentrate t i l l slaughter. Daily dry matter intake was i n i t i a l l y 5.90 kg/head/day. . The'crude protein intake was about .56 kg/head/day. Daily dry matter intake rose as the steers got bigger. A l l treatments had the same l e v e l of a vitamin-mineral mixture throughout the feeding t r i a l s . 29 Method of estimation of carcass composition by u l t r a s o n i c s The u l t r a s o n i c r e f l e c t i o n method of estimation of carcass composition was adopted. Use was made of a Krautkramer. USM2F model. The probing was done by an experienced operator from the Livestock Branch of A g r i c u l t u r e Canada. Probing was at monthly i n t e r v a l s from the s t a r t of the experiment u n t i l i t s termination. A l l steers were also u l t r a s o n i c a l l y probed one day p r i o r to slaughter. For the routine probing, the steers were restrained i n a squeeze chute. The h a i r was clipped as recommended by Hazel and Kline (1959). A motor o i l (SAE 30 weight) was applied l i b e r a l l y to the area where the u l t r a s o n i c estimates were to be made. The reference point for measuring, between the 11th and 12th r i b , was determined by palpation. Two measurements of lean depth were taken i n the region of the 11th and 12th r i b at points which were one-third and two-thirds the estimated l a t e r a l length of the r i b eye muscle. Fat depth measurements were obtained at the same points as the r i b eye muscle determinations. D i g e s t i b i l i t y t r i a l s According to Blaxter and Wainmann (1964) d i g e s t i b i l i t y figures obtained with sheep are i n most cases s i m i l a r to those obtained with c a t t l e on the same diets.' The d i g e s t i b i l i t y of a l f a l f a cubes (Ration 3) and the 50%, barley-50% a l f a l f a r a t i o n (Ration 2) was determined using s i x growing ewes (three ewes per ration) of the Dorset breed. The sheep used i n this d i g e s t i b i l i t y t r i a l had previously been used in s i m i l a r t r i a l s and were therefore used to handling. The ewes were confined i n si n g l e pens. Feed and water were provided. 920 g ( a i r dry weight) of the crushed a l f a l f a cubes or 930 g ( a i r dry weight) of the a l f a l f a - b a r l e y r a t i o n were provided d a i l y . Feeding was done twice d a i l y , at 8:00 a.m. and 3:00 p.m.. The 30 composition of both rations was the same as was used i n the beef c a t t l e t r i a l s . The ewes were put on the experimental diet for a 7-day t r a n s i t i o n period. Subsequently, for f i v e days, four grams of chromic oxide i n cap-sules were administered per day, two grams at each feeding. In the l a s t two days of the t r i a l , the flo o r s of the pens were covered with jute sacking to a i d the c o l l e c t i o n of fec a l samples free of urine. The fec a l samples were dried and compounded for the two days. Sub samples were taken for proximate analysis, by methods of the A.O.A.C. (1970). Determination of chromic oxide i n the feces was by a modification of the method of Stevenson and De Langen (1960). The modification involved the method of obtaining the standard curve for estimating the amount of chromic oxide i n the fec a l sample and hence of estimating the feces production of the experimental animals. In the modified method used, to one gram samples of feces free of chromic oxide and c o l l e c t e d from the same experimental animal, are added 1 mg, 2 mg, 4 mg, 5 mg, and 8 mg r e s p e c t i v e l y of chromic oxide. The fec a l samples so treated were then ashed and treated according to the procedure described by Stevenson and De Langen (i960). A blank was run on chromic oxide-free feces and reagents. The stan-dard curve was drawn based not on potassium dichromate as proposed by Stevenson and De Langen, but on the known amount of chromic oxide i n each fec a l sample. Absorbance was read at wavelength 400 mu i n a Spectronic 20 spectrophotometer. A standard curve was drawn of o p t i c a l density versus concentration of dichromate i n the various f e c a l samples Determination of carcass composition at the end of the t r i a l s The feeding t r i a l s were terminated for each group when the average pen l i v e weight approximated 430 kg. The steers were weighed and probed for fat thickness and area of r i b eye muscle before being shipped to the packing house. Before transportation to the packing house, the animals were held of f feed or water for 12 hours. After slaughter, weights were recorded of the hot unwashed carcasses. Dressed weight was determined and each carcass was cut l o n g i t u d i n a l l y into l e f t and r i g h t sides. A f t e r a 24 hour c h i l l * i n a 1.7°C cooler, the r i g h t side of each carcass was ribbed between the 11th and 12th r i b . The area of the longissimus d o r s i muscle was determined using a p l a s t i c g r i d . Duplicate measurements were made on each r i b eye muscle. A sing l e fat thickness measurement was taken and qua l i t y and y i e l d grade assigned (C.D.A. 1972). Marbling score was also assigned. For the Record of Performance (ROP) the average of two fat depth measurements were used. These measurements were taken over the same points used to estimate the area of the r i b eye muscle. Measurement of the area of the r i b eye muscle was also made using acetate paper. Acetate paper was placed d i r e c t l y over the r i b eye muscle of the c h i l l e d carcass and i t s area traced on the paper. Subsequently a compensating planimeter was used to determine the area of the r i b eye muscle. Duplicate measurements were made on each tra c i n g using the p l a n i -meter. The a n a l y t i c a l methods Dry matter determination: Dry matter determinations were made on t r i p l i c a t e samples of feeds and pre-dried feces by drying to a constant weight i n a forced draught oven. Nitrogen determination: Nitrogen determinations were made i n t r i p l i c a t e on feeds and feces according to the macrokjeldahl method (A.O.A.C. 1970). Nitrogen content of the feeds and feces were converted to crude protein by multiplying with a factor of 6.25 and the r e s u l t was expressed as a percentage of the i n i t i a l sample dry matter. D i g e s t i b l e crude protein values were obtained using the percentage d i g e s t i b i l i t y figures for crude protein. Acid detergent f i b r e : Acid detergent f i b r e (ADF) was determined on both feeds and feces according to the method of Van Soest (1963). Ash determination: . Ash was determined on the feeds and feces by heating a known weight of the sample i n a muffle furnace at 600°C for four hours (A.O.A.C. 1970). Ether extract determination: Ether extract was determined on the feed samples according to the methods of the A.O.A.C. (1970). The ether extract content was expressed as a percentage of the sample dry matter. Gross energy determination: Gross energy was determined on feeds and feces using the Gallenkamp it Adiabatic bomb calorimeter and the r e s u l t s were expressed as k i l p c a l o r i e s per gram of dry matter. A l l determinations of dry matter, gross energy, nitrogen, acid "Gallenkamp Adiabatic bomb calorimeter manufactured by: A. Gallenkamp and Company Limited, Christopher Street, London, E.C.2. 33 detergent f i b r e , ash and ether extract were made i n t r i p l i c a t e and the mean value calculated. Treatment of the a n a l y t i c a l data . From the d i g e s t i b i l i t y t r i a l s , the apparent d i g e s t i b l e energy values were calculated. These were corrected with a factor of 0.82 (Garret e_t a l . 1959 to obtain ah estimate of metabolizable energy. Growth was measured as average d a i l y gain (ADG) for each animal over varying periods of time. Individual feed e f f i c i e n c y r e s u l t s could not be determined as the experi-mental animals were group fed. Group feed e f f i c i e n c y r e s u l t s were, however, calculated. Feed e f f i c i e n c y of the groups of steers on the d i f f e r e n t rations was expressed i n terms of both kilogram/feed per kilogram body weight gain and Mega c a l o r i e s metabolizable energy ingested per kilogram body, weight gain. A l l data on growth rate and carcass.compos i t ion (but not feed e f f i c i e n c y or feed costs per kilogram gain) were subjected to an . analysis of variance (Steel and T o r r i e 1960). Differences between means Of treatments were tested by Duncan's New Mu l t i p l e Range Test (Duncan 1955). A c o r r e l a t i o n analysis was run between the r i b eye area estimated by the ul t r a s o n i c technique and the actual r e s u l t s obtained from measurements on i the carcass using either p l a s t i c grids or tracings on acetate paper. RESULTS The r e s u l t s of the proximate analysis are presented in Table 1, while the gross, d i g e s t i b l e and metabolizable energy values of the feeds are shown in Table 2. Table 1: A proximate analysis of samples of feed material (DM basis) Feed Ingredient DM % Ash % ' ADF 7, Ether Extract % CP %. Rolled barley 91.27 2.32 ' 8.32 2.40 10.90 A l f a l f a cubes 91.26 9.44 30.01 2.87 17.32 Protein supplement 9.1.73 13.52 - 4.55 31.44 DM = Dry matter; ADF = Acid Detergent Fibre;. CP = Crude Protein; OM = Organic Matter. Results of a l l analyses presented i n this work have been expressed on a dry matter basis. Table 2: Energy value of feed ingredients (k cals/g) (DM basis) Feed Ingredient Gross Energy D i g e s t i b l e Energy Metabolizable Energy Rolled barley 5.06 3.61 2.96 A l f a l f a cubes 4.49 2.69 2.21 Pr o t e i n supplement" •4.11. 3.08 2.53 ; Mineral supplement''" 3.87 2.92 2.39 The d i g e s t i b i l i t y c o e f f i c i e n t s of the three main rations used in the experiment are presented i n Table 3. D i g e s t i b i l i t y c o e f f i c i e n t values for barley were obtained from the l i t e r a t u r e (Watson et al. 1948). ^Obtained brom Buckerfield's Ltd., Vancouver, B r i t i s h Columbia, Canada. Table 3: . D i g e s t i b i l i t y c o e f f i c i e n t s of some of the rations used i n the experiment Ration. DM % . OM 7» CP % " ADF 7„ Rolled barley 81.4 82„7 76.8 34.0 A l f a l f a cubes 67.92 69.62 78.13 56.15 Alfalfa-barlev 73.65 75.85 80.22 50.63 E f f e c t of the d i f f e r e n t rations on growth rate, feed e f f i c i e n c y and carcass  composition (a) Growth rate: The growth rates of the steers were expressed as average d a i l y gain. Results of the analysis of data for growth rate are presented i n Table 4. Table 4: Average growth rate of steers on the d i f f e r e n t r a t i o n treatments I n i t i a l Body F i n a l Body Average Daily Ration Treatments Weight (kg) Weight (kg) Gain (kg) a a 1. Rolled barley a l l through 221.13 429.56 1.07 2...507. r o l l e d barley, 507o 225.12 415.95 1.03 a l f a l f a cubes 3. A l f a l f a cubes a l l through 222.72 434.09 0.84 b 4. Rolled barley followed by 221.58 ' 440.22 0.97 a b a l f a l f a 5. A l f a l f a followed by 221.59 453.50 1.06a r o l l e d barley Standard error 5.15 8.74 0.04 a,b means which have the same superscripts are not s i g n i f i c a n t l y d i f f e r e n t from each other P<0.05. Only the a l l - a l f a l f a r a t i o n was s i g n i f i c a n t l y d i f f e r e n t from the others i n terms of average growth rate of steers. The 1007, barley ration, the b a r l e y - a l f a l f a r a t i o n as well as the alfalfa-followed-by-barley r a t i o n were quite, s i m i l a r . The body weight changes of steers on the three main rations (barley, a l f a l f a and b a r l e y - a l f a l f a ) are presented g r a p h i c a l l y (Fig. 1). (b) Feed e f f i c i e n c y : The e f f i c i e n c y of feed u t i l i z a t i o n - w a s determined for each group of steers on each r a t i o n either as kg feed/kg gain or as M c a l . metabalizable energy/kg gain. Group feed e f f i c i e n c y r e s u l t s were not subjected to s t a t i s t i c a l a n a l y sis. Results are presented i n Table 5... Table 5: Group feed e f f i c i e n c y of Hereford steers on the d i f f e r e n t r a t i o n treatments over varying periods of growth (kg feed/kg gain) Ration Treatments 4th wk. 8th wk. 12th wk. 16 th wk. 20 th wk. , 24th wk. . 1st-End 1, Rolled barley 6.40 5.53 6.12 6.32 5.82 7.08 7.01 •2. 50% barley, 50% a l f a l f a 6.39 .7.61 8.18 9.69 7.32 11.30 8.29 3. A l f a l f a cubes 7.30 9.93 11.80 11.10 11.32 20.03* 11.29 4. Barley followed by a l f a l f a 6.36 5.21 5.40 7.92 12.67 10. 29 8.71 5. A l f a l f a followed by barley 7.44 8.60 10.79 21.02* 10.73 7.49 9.05 ^Occurrence of bloat may be responsible for the low feed e f f i c i e n c y . The a l l - b a r l e y r a t i o n promoted a^consistently high feed e f f i c i e n c y either at the beginning or at the end of the t r i a l s . > Steers on the mixed r a t i o n (barley and a l f a l f a ) also had a r e l a t i v e l y high feed e f f i c i e n c y throughout the t r i a l s , although the feed e f f i c i e n c y tended to f a l l at the l a s t month of the experiment. Feed e f f i c i e n c y was low among the steers on the a l l - a l f a l f a r a t i o n , while i t was intermediate among those on the switched rations. F i g . 2 i l l u s t r a t e s the changes i n feed e f f i c i e n c y of the J7 Fig I. BODY WEIGHT C H A N G E S IN S T E E R S FED THREE TYPES OF RATION . (Kg) • • • ALFALFA 4 0 0 WEIGHT • i (Kg) 3 5 0 3 0 0 2 5 0 2 0 0 1 I B A R L E Y - A L F A L F A BARLEY • • * • • • '•{. ::}. • • • • • • • • •TV v*' i .*-;* • • • • « V ; • • • *%j. « • \ ." • • '*."*• • >v. • i • > i St , th 8 ,th 12 T H 1 6 T H 2 0 T H 2 4 th PERIOD (weeks) Fig 2a. PERIODIC GROUP FEED CONVERSION RATIO OF HEREFORD STEERS FED THREE TYPES OF RATION . (Kg feed/Kg gain) 2 0 r FOR. (Kg/Kg) 15 10 i th SS BARLEY BARLEY-ALFALFA S 3 ALFALFA 8' , th 12'" 16th 20™ 2 4 PERIOD (weeks) th Note that the occurrence of bloat i n the 24th week may be responsible for part of the high feed conversion r a t i o . steers on the three main r a t i o n treatments. as the t r i a l progressed. In Table 6 the feed e f f i c i e n c y r e s u l t s are expressed i n terms of M cals metabolizable energy per kilogram of body weight gain. Figure 2b is a graphical representation of the periodic changes i n feed e f f i c i e n c y as the t r i a l continued. The feed e f f i c i e n c y is expressed as M cals ME/kg weight gain. Table 6: Group feed e f f i c i e n c y of Hereford steers on the d i f f e r e n t r a t i o n treatments, over varying growth periods (M cals ME/kg gain) 4th 8th 12th 16th 20 th 24th . l-24th Ration Treatments wk. wk. wk. wk. wk. wk. wk. 1. Rolled barley .17.74 15.69 17.31 18.21 16.89 20.56 17.73 2. 50% barley, 50% 16.08 19.31 20.57 24.48 19.1.1 29.0.0 21.39 a l f a l f a 3. A l f a l f a cubes 16.20 22.03 25.10 24.63 25.11 44.41*'" 26.25 4. Barley followed by 17.19 14.77 15.30 23.53 28.10 22. 81 20. 28 a l f a l f a 5. A l f a l f a followed by 16.53 20.15 24.39 47.88" 26.79 20.48 26.03 barley "Occurrence of bloat. . (c) Carcass composition: None of the r a t i o n treatments s i g n i f i c a n t l y a f f e c t e d the carcass components. The r e s u l t s of the effect, of the d i f f e r e n t rations on average carcass fat, area of r i b eye muscle and carcass weight are shown in Table 7. Table 8 presents the influence of the r a t i o n treatments on Dressing percentage and per cent c u t a b i l i t y of the carcass. There was a s i g n i f i c a n t difference (P^O.05) between the rations i n respect of dressing percentage but the per cent c u t a b i l i t y of the carcasses was not s i g n i f i c a n t l y d i f f e r e n t . Fig 2b. GROUP FEED CONVERSION RATIO OF HEREFORD STEERS ON THE DIFFERENT RATIONS. ( M cal.ME/ Kg.GAIN) 45 r FC.R. (Meal/Kg) 401 35 30 25 15 BARLEY BARLEY-ALFALFA •V.*.] ALFALFA ith 8 th 12 th 16th 2.0th 24th PERIOD (weeks) Bloating occurred among the steers on; a l f a l f a during the 24th week. Table 7: E f f e c t of the d i f f e r e n t rations on carcass components Av. Carcass Rib Eye Area Carcass Weight Ration Treatments .- Fat (cm) (sq cm) , (kg) 1. Rolled barley 1.37 68.06 242.18 2. 50% barley, 50% a l f a l f a 1.37 63.03 231.7.0 3. A l f a l f a cubes 1.19 63.74 . 235.78 4. Barley followed by 1.27 63.68 237.73 a l f a l f a . 5. A l f a l f a followed by 1.27 66.58 ' 249.87 barley . ' Standard error 0.10 , 1.55 ' 4.58 There were no s i g n i f i c a n t differences between the means P< 0.05 Table 8: E f f e c t of r a t i o n treatments on Dressing percentage and c u t a b i l i t y  of steer carcasses Ration Treatments Dressing % C u t a b i l i t y % 1. Rolled barley 56.42a 56.63 2. 50% barley, 50% a l f a l f a 55.74a 56.04 3. Alfalfa cubes 54.31b 56.76 4. Barley followed by a l f a l f a 54.00b 56.41 5. A l f a l f a followed by barley 55.44 56.72 : Standard error 0.36 0.28 Means with d i f f e r e n t superscripts are s i g n i f i c a n t l y d i f f e r e n t P< 0.05 The a 11— bar ley r a t i o n as well as the 50%, barley, 50%, a l f a l f a r a t i o n gave r i s e to. higher dressing percentages i n the steers than the other rations. The steers which were switched from a l f a l f a to barley showed 42 s i m i l a r dressing percentages as those on the a l l - b a r l e y or the barley and a l f a l f a r a t i o n . The e f f e c t s of switching the steers from barley to a l f a l f a and v i c e versa were also studied. The r e s u l t s are presented in Table 9. Switching the steers from.an a l l - b a r l e y r a t i o n to a l f a l f a cubes was easier than switching them from a l f a l f a cubes to barley. This was despite the fact, that precautions had been taken to prevent the occurrence of bloat. The steers started on barley had a group feed e f f i c i e n c y of 5.72 kg feed per kg gain but when switched on to cubes, the feed e f f i c i e n c y dropped to 13.24 kg feed per kg gain. Steers started on a l f a l f a cubes had a feed e f f i c i e n c y of 9.16. When., however, they were slowly switched on to barley, two animals in the group developed bloat and died, another one became a chronic bloater. Consequently, the r e s u l t s of the l a t e r part of the t r i a l were not as good as expected. Table 9: E f f e c t of switching rations on group feed e f f i c i e n c y Ration Treatment ; Day 1 to Switch Switch to End Barley followed by cubes 5.72 13.24. Cubes to barley' 9.16 10.27* 'Three steers in this group developed bloat The e f f e c t of implantation of 36 mg Ralgro on growth rate, f e e d - e f f i c i e n c y  and carcass composition of Hereford steers (a) Growth rate: The performance of implanted and unimplanted steers i s summarized i n Table 10. 43 Table 10: E f f e c t of Ralgr o implantation on growth rate and carcass composition. Parameter Mean Values Implanted Steers Unimplanted Steers S.E. I n i t i a l body weight (kg) 221.59 221.72 2.66 F i n a l body weight, (kg) 433.55 435.73 4.52 Average d a i l y gain (kg) 1.10 0.90 0.02 Average carcass fat (cm) 1.24 1.35 0.46 Rib eye area (sq cm) 65.55 65.10 0.84 Dressed carcass weight (kg ;) 239.44 239.44 2.39 Dressing percentage 55.27 54.99 0.18 C u t a b i l i t y per cent 56.70 56.32 0.14 Implanted steers were not s i g n i f i c a n t l y d i f f e r e n t from unimplanted steers P< 0.05. From the r e s u l t s , i t can be seen that over the entire experimental period, the implanted steers were not s i g n i f i c a n t l y different.from the un-implanted steers in either growth rate or carcass composition. Implanta-t i o n did not a f f e c t dressing percentage or y i e l d of carcass. Perry et a l . (1970) had suggested that the anabolic e f f e c t of Ralgro was depleted within 84 to 112 days. Research workers at the A g r i c u l t u r e Canada, Melfort Research Sta t i o n (1971) had reported that most of the response to Ralgro occurred within the f i r s t nine weeks post implantation. The growth data i n this experiment were consequently analysed for the period Day 1 to Day 60 post implantation. Table 11 presents the body weight changes which occurred within 60 days post implantation. Table 11: Body weight changes within 60 days post implantation of Ralgro Parameter • Implanted Steers Unimplanted Steers Average i n i t i a l body weight (kg) 310.03 309.81 Average f i n a l body weight (kg) 374.22 367.64 Average change in body weight (kg) 64.18" 57.83 Average d a i l y gain (kg) . . 1.07'f 0.97 '"Significant at P< 0.05 The results c l e a r l y indicate that within 60 days a f t e r implantation of 36 mg Ralgro, the growth rate of the steers so treated was s i g n i f i c a n t l y greater than controls. (b) Feed e f f i c i e n c y : Individual feed e f f i c i e n c y values were not calculated because the steers were group fed. Group feed e f f i c i e n c y r e s u l t s c a l c ulated were not subjected to s t a t i s t i c a l a n a l y s is. Table 12 summarizes the observed re-su l t s of the e f f e c t of Ralgro implantation on feed e f f i c i e n c y . Table 1.2: E f f e c t of Ralgro implantation on group feed e f f i c i e n c y of Hereford  steers (kg feed/kg gain) Ration Treatment Over a l l Feed E f f i c i e n c y Feed E f f i c i e n c y Over 60 Days Implanted Unimplanted Implanted Unimplanted 1. Rolled barley 6.59 7.44 5.69 6.70 2. 50% barley,50% a l f a l f a 8.29 8.30 7.81 8.82 •3. A l f a l f a cubes 11.29 11.28 10.59 11.82 4. Barley followed by 8.67 .8.75 9.53 10.16 a l f a l f a , 5. A l f a l f a followed by 8.43 10.87 . 9.16 20.01 barley 41) It can be seen that implantation improved the feed e f f i c i e n c y of the groups either over the e n t i r e duration of the t r i a l s or over a 60 day period post implantation. The e f f e c t was more marked over the 60 day period.. • (c) Carcass composition: The carcasses of the implanted and unimplanted steers were compared in respect of such carcass components as area of r i b eye muscle and average carcass fat and such carcass c h a r a c t e r i s t i c s as dressing percentage and c u t a b i l i t y . There were no s i g n i f i c a n t differences between the carcasses of implanted and unimplanted steers. There was, however, a s l i g h t i n -crease i n the area of r i b eye muscle, dressing percentage and c u t a b i l i t y of the implanted as compared to the unimplanted steers. The fat cover over the r i b eye muscle was s l i g h t l y smaller in the implanted steers. Feed costs per kilogram gain on the d i f f e r e n t rations The cost of feed ingredients used i n the experiment i s presented i n Table L3. . ' Table 13: Cost of feed ingredients Cost Per Kilogram (moisture free) Ingredients Cost Per Ton Steam r o l l e d barley- $140 16.90 A l f a l f a cubes $107 13.00 Protein supplement $171 20.70 Mineral supplement $145 17.6<? Three time periods were considered i n the computation of feed costs per kilogram gain. These were (a) the f i r s t twelve weeks of growth (a period of very rapid growth rate), (b) the 13th to 20th week during which growth was not so rapid, and (c) from the f i r s t week to either the 20th week or the 28th week. Total feed consumption was calculated for a l l groups of animals on the d i f f e r e n t rations. Total feed consumption was calculated on a dry matter basis. The cost per unit weight of oven-dry ingredients was used to compute the t o t a l costs, of feed consumed by each group of steers. Group l i v e weight gains over corresponding periods of time were determined. Feed costs per kilogram body, weight gain were, sub-sequently calculated. The feed cost per kilogram weight gain is summarized in Table 14. Within the f i r s t 12 weeks of the t r i a l , there was l i t t l e or no difference between the a l l barley r a t i o n , the 507, barley r a t i o n and the r a t i o n i n which barley was followed by a l f a l f a . In the period week 13 to week 20 feed cost per kilogram gain was lowest for the barley r a t i o n , s l i g h t l y more expensive on the 507, barley-507> a l f a l f a r a t i o n and s t i l l more expensive on the a l f a l f a and switched rations. Over the period week 1 to week 20 or week 28, feed cost per kilogram gain was lowest for the steers on the barley ration, followed by those on the 507. barley ration.. The highest feed cost per kilogram gain was among the animals on the a l f a l f a r a t i o n . Feed costs were intermediate in the rations that were switched. The steers on the a l f a l f a r a t i o n and the switched rations grew at a slower rate than those on the a l l - b a r l e y or 507. barley r a t i o n , and con-sequently the former took well over 28 weeks to a t t a i n an average weight of 385 kg compared to the 20 weeks i t took the l a t t e r . The extra eight weeks of feeding cost $395 for the groups on a l f a l f a and $387.5 and $251.84 for groups on barley to a l f a l f a and a l f a l f a to barley respectively. Table 14: Feed cost per kilogram weight gain i n Hereford steers 47 Group Feed Live Weight Time Period Costs Gains Feed Cost/kg Gain Ration Treatment (wks) $ . (kg) $ A l l barley 1st - 12th 13th - 20th 1st - 20th 433.36 346.66 780.02 454.73 360.62 815.35 0.95 0.97 0.96 50% barley, 50% a l f a l f a 1st - 12th 472.85 460.40 13th - 20th 413.11 353.81 1st - 20th 885.96 814.21 1.03 1.17 1.09 A l f a l f a cubes 1st - 12th 436.07 387.83 13th - 20th 359.67 268.76 1st - 28th 1190.73 . 878.85 1.12 1.34 1.36 Barley followed by a l f a l f a 1st - 12th 431.70 493.29 13th - 20th 338.29 250.61 1st - 28th 1157.49 968.44 0.87 1.35 1.19 A l f a l f a followed by barley 1st - 12th 13th - 20th 1st - 28th 437.54 287.06 97 6.44 390.10 390.10 793,80 1.13 1.13. .1.23 Comparison o f ' u l t r a s o n i c probe prediction'of r i b eye area with actual area  of r i b eye as measured by acetate paper tracings and by the p l a s t i c g r i d  method Rib eye area as predicted, by the u l t r a s o n i c probe was compared to measurements of actual area of r i b eye as determined by acetate paper tracings and the p l a s t i c g r i d method. Co r r e l a t i o n analyses were run be-tween r i b eye' area as estimated or measured by these methods. The r e s u l t s are summarized i n Table 15. Table 15: Co r r e l a t i o n analysis of r i b eye area as determined by (a) the  ul t r a s o n i c probe, (b) planimeter measurement of acetate paper  tracings, (c) the p l a s t i c g r i d method Correlations Parameter Means Std. Error Ax A 2 A3 A4 I n i t i a l body weight (A-^ ) 222 kg 16.48 kg Probe p r e d i c t i o n of r i b 63.90 sq.cm 4.06 sq cm eye (A 2) Planimeter measurement 67.09 sq cm 5.81 sq cm 0.10 0.2.7 of acetate paper trac-ings (A3) P l a s t i c g r i d method 65. 87 sq cm 6.0 sq cm 0.30 0.72. (A 4) The r e s u l t s indicated that there was r e l a t i v e l y l i t t l e r e l a t i o n s h i p (r = 0.27) between the area of r i b eye muscle as predicted by the u l t r a -sonic probe and that traced on the carcass using acetate paper. There was also l i t t l e r e l a t i o n s h i p (r = 0.30) between the r i b eye area measurements by the u l t r a s o n i c probe and the gri d method. There was, however, a high c o r r e l a t i o n c o e f f i c i e n t (r = 0.72) between r i b eye area data as obtained by planimeter measurements of acetate paper tracings and those obtained from the p l a s t i c g r i d method. 49 DISCUSSION OF RESULTS E f f e c t of the d i f f e r e n t r a t i o n treatments on growth rate, e f f i c i e n c y of  feed u t i l i z a t i o n and carcass composition (a) Growth rate: The r e s u l t s of t h i s study showed that there was a s i g n i f i c a n t d i f -ference in growth rate between the all—roughage r a t i o n and those i n which some barley was included. I t also c l e a r l y demonstrated that no s i g n i f i c a n t l y higher growth rate occurred i f the barley content of the r a t i o n was raised from 50% (Ration 2) to 100%. (Ration 1). The r e s u l t s also indicated that as far as growth rate was concerned, there was no d i f f e r e n c e between the steers started on a l f a l f a cubes and f i n i s h e d on grains and those started on grains and finished on a l f a l f a cubes. That there is a s i g n i f i c a n t d i f f e r e n c e be-tween the growth rate of steers fed on roughages as compared to those fed on concentrates is well documented in the l i t e r a t u r e ( M i l l e r et a l . 1967, Woods and Scholl 1962, Bucy and Bennion 1962). Steers must ingest enough energy to meet maintenance requirements and excess energy for growth. Voluntary feed intake is a factor which l i m i t s the amount of energy that can be i n -gested. Bulk and coarseness of the feed as well as i t s p a l a t a b i l i t y and physical l i m i t a t i o n of the rumen capacity of the animal, are some of the factors which influence voluntary feed intake. Hence, i f two steers of the same s i z e are fed to appetite, one on r o l l e d barley and the other on a l f a l f a cubes, the steer on the barley r a t i o n would ingest more metabolizable energy and would therefore grow faster than the one on a l f a l f a cubes. The r e s u l t s reported here show no s i g n i f i c a n t difference i n growth rate between steers fed the a l l - b a r l e y r a t i o n and those fed the 50% barley r a t i o n . Results published in the l i t e r a t u r e , e s p e c i a l l y those of Richard-50 son e_t a_l. (1961) have shown that though the largest average d a i l y gains were produced when c a t t l e rations contained up to 837, concentrates, there was no s i g n i f i c a n t difference between such rations and those that con-tained 50% concentrates. In that case, therefore, i t might be considered advantageous for a farmer to adopt the 50%.'.barley, r a t i o n rather than the more c o s t l y a l l — b a r l e y r a t i o n . Results observed in this t r i a l did show that as far as growth rate was concerned, a farmer might just as e a s i l y s t a r t his young steers on • a l f a l f a cubes and f i n i s h them on grains as he would s t a r t them on grains and f i n i s h on cubes. Switching the.rations at 340 kg l i v e weight did not a f f e c t the growth rate of the animals so treated. Various opinions have been expressed over the r e l a t i v e merits of feeding high energy rations early or l a t e i n the l i f e of a beef steer. S t a r t i n g the steers on roughages followed by a switch to grains has been compared to realimentation of poorly nourished animals. Waters (1908) however, noted that "an animal that i s below the normal s i z e at a given age, through poor nourishment, apparently has the capacity when l i b e r a l l y fed, to compensate for this loss in measure at l e a s t by an.increased rate of growth." Subsequent experiments (Benedict and Ritzman 1929, Winchester and Howe 1955) have indicated that animals subjected to retarded growth due to under-nutrition more than compensate for this retardation when l i b e r a l l y fed. The steers started on the barley r a t i o n were expected to show a rate growth commensurate with the l e v e l of ingested energy. When they were switched to roughages, the rate of growth was expected to slow down considerably. The f i n a l r e s u l t would therefore be that steers on both types of rations performed equally well. This was the case with the r e s u l t s observed in this experiment. 51 (b) Feed e f f i c i e n c y : The data on group feed e f f i c i e n c y were not subjected t^ o s t a t i s t i c a l analysis and differences between rations could therefore not be said to be s i g n i f i c a n t . " • The feed e f f i c i e n c y data for the a l l — b a r l e y r a t i o n and the 507, barley r a t i o n indicated that.there was no d i f f e r e n c e between these rations, nor was there any difference between these rations and the barley-to-cubes r a t i o n up to 16 weeks. The a l f a l f a r a t i o n as well as the a l f a l f a - f o l l o w e d -by-barley r a t i o n showed con s i s t e n t l y low feed e f f i c i e n c y . From the 20th week,the feed e f f i c i e n c y of steers on the a l f a l f a - t o - b a r l e y r a t i o n rose considerably. This corresponded to the period when the steers were switched to the barley d i e t . Published r e s u l t s on feed e f f i c i e n c y p a r a l l e l those on growth rate. Rations composed l a r g e l y of grains give r i s e not only to high growth rate, but also high feed e f f i c i e n c y . There has been shown a l i n e a r increase in both growth rate and feed e f f i c i e n c y with increasing l e v e l s of grain i n the r a t i o n . This occurs u n t i l an optimum l e v e l of incorporation is reached, suggested at about 507, concentrates (Richardson e_t a l . 1961) or 707, concen-trates (Lamming e_t a l . 1966) depending on the age and weight of the c a t t l e . Richardson' and coworkers (1961) reported no s i g n i f i c a n t d i f f e r e n c e between a r a t i o n containing 507, concentrates and one containing 837,, while Lamming and coworkers observed no s i g n i f i c a n t difference between rations containing 707, concentrates and those containing 1007, concentrates. In Figs. 2 and 2b feed e f f i c i e n c y was expressed as kg feed/kg gain or as M cals metabolizable energy/kg gain r e s p e c t i v e l y . In the three rations considered, feed e f f i c i e n c y f e l l r a p i d l y a f t e r the 20th week. This occurred independent of the nature of the r a t i o n . It therefore seemed obvious that the f a l l i n 52 feed e f f i c i e n c y corresponded to a ph y s i o l o g i c a l change in the steers:, when ingested energy was s h i f t e d from growth to fattening. Fattening is less e n e r g e t i c a l l y e f f i c i e n t than growth and i t s onset was marked by the steep f a l l i n feed e f f i c i e n c y . (c) Carcass composition: Results from this experiment indicated that there was no s i g n i f i c a n t d i f f e r e n c e i n such carcass components as average carcass fat and area of r i b eye muscle between the steers fed on the d i f f e r e n t r ations. Swan and Lamming (1967) as well as Martin e_t al_. (1966 ) have reported a l i n e a r increase i n per cent carcass fat and no e f f e c t on carcass lean when the grain content of the r a t i o n was increased. Cooke e_t a l . (1972) reported not only a l i n e a r increase i n per cent carcass fat but also a l i n e a r de-crease i n carcass lean with increasing energy intake. The res u l t s reported here on the average carcass fat is at variance with published findings. It is known that as the cereal concentration i n the die t increases, there is a corresponding increase i n dietary metabolizable energy and therefore a tendency to deposit more carcass f a t . Reduction of the energy intake of steers depresses carcass fat deposition, whether the reduction is by d i l u -t i o n of the ration.with roughages or by feeding only roughages. A possible explanation for this discrepancy is that the steers on the a l l - b a r l e y r a t i o n were fed to appetite rather than ad-libitum as reported by these other Workers. Usually the continuous presence of feed i n the trough encouraged animals to consume very high l e v e l s of energy, le v e l s much higher than they would eat when fed only to appetite. It is postulated that the steers in this experiment consumed enough energy for the i r maintenance and production, but not so much that excessive amounts of adipose t i s s u e would be l a i d down. 53 Hence, there was no s i g n i f i c a n t d i f f e r e n c e between the rations in respect of the average carcass fat of steers fed on these rations. E f f e c t of Ralgro implantation on growth rate, feed e f f i c i e n c y and carcass  compos i t ion : (a) Growth rate: Though many workers have indicated that over the e n t i r e growth period, implantation of 36 mg Ralgro promotes responses i n growth s i m i l a r to those obtained with d i e t h y l s t i l b e s t r o l (DES), the r e s u l t s of this study show that response to Ralgro implantation occurred only within 60 days post implanta-t i o n . Within this period, growth rate was shown to be s i g n i f i c a n t l y higher i n implanted steers as compared to controls. That depletion of the implant occurred early was reported by Perry et_ a_l. (1970) and by workers at the Melfort Research S t a t i o n (1971). Perry and coworkers showed that the depletion occurred from 84 days post implantation while the Melfort workers put i t at 63 days. Within 60 days of implantation, the s i g n i f i c a n t growth rate reported in this t r i a l agreed with other r e s u l t s in the l i t e r a t u r e (Embry and Graber 1969, Brown 1970, Perry et a l . 1970). (b) Feed e f f i c i e n c y : In Table 12, the e f f e c t of implantation of Ralgro on group feed e f f i c i e n c y was presented. A study of the r e s u l t s indicates that whereas over the e n t i r e experimental period there was no difference i n feed e f f i c -iency between the implanted and unimplanted steers, within 60 days post -implantation, there was a noticeable difference between the group feed e f f i c i e n c y of.the implanted steers as compared to controls. I t may be suggested, therefore, that the steers should have been reimplanted at the end of 60 days. Brown (1970) had, however, reported increases in feed e f f i c i e n c y which ranged from 4.32% with feedlot h e i f e r s to 7.8% i n feedlot steers over growth periods of 140 days following single implants i n these animals. (c) Carcass composition: Most work reported i n the l i t e r a t u r e has not shown any e f f e c t of Ralgro implantation on carcass composition. Carcass grades have also been reported to be e s s e n t i a l l y the same' for implanted and unimplanted steers. Workers at the A g r i c u l t u r e Canada Melfort Research Sta t i o n (1972) reported that whereas carcass y i e l d s , grades and q u a l i t y were not d i f f e r e n t between implanted and unimplanted steers, there was a s l i g h t tendency for carcasses of implanted animals to carry less fat cover over the r i b eye muscle at the point of quatering and to have a s l i g h t l y larger eye muscle area. In the present study, there was a s l i g h t increase i n the area of the r i b eye muscle, the dressing percentage and c u t a b i l i t y of the carcasses of implanted steers as compared to controls. The fat cover over the r i b eye muscle was also s l i g h t l y smaller i n the steers implanted with Ralgro. Feed costs per kilogram weight gain . • Average feed costs.per kilogram weight gain were lowest for the steers fed on barley ($0.96) and highest for those on only a l f a l f a cubes ($1.36). The steers fed on a mixed r a t i o n of a l f a l f a and barley had feed costs which were almost as low as those fed on barley alone. For the steers which were switched either from a l f a l f a cubes to barley or from barley to cubes, feed costs per kilogram gain were moderate. From Table 4 i t can be seen that there was a s i g n i f i c a n t d i f f e r e n c e in growth rate between steers on the a l f a l f a cubes (Ration 3) and those on the other rations. In other words, whereas the a l f a l f a r a t i o n sustained a r e l a t i v e l y poor, growth, a l l the other rations performed w e l l . A l f a l f a cubes were therefore not only the poorest for growth, but also the most expensive r a t i o n to r a i s e steers on. Since a l l the other rations were not s i g n i f i c a n t l y d i f f e r e n t from each other for growth, i t became important to consider t h e i r costs per kilogram weight gain. The switched rations were more expensive than the rations which con-tained either a l l - b a r l e y or 50% barley. S i m i l a r l y , the a l l - b a r l e y r a t i o n was cheaper than the 50%. barley r a t i o n . It is cle a r , therefore, that the barley r a t i o n would be recommended even at the p r e v a i l i n g cost of feed i n -gredients. There is a tendency for farmers to consider only the cost of the fee ingredient when they are faced with a choice of what to feed. Granted that a l f a l f a hay or cubes is cheap, the question a r i s e s , "How much energy does the steer get out of i t ? " The d i g e s t i b i l i t y of nutrients from a l f a l f a is much lower than those from grains. As a r e s u l t , not only the d i g e s t i b l e energy (DE) but also the metabolizable energy (ME) is lower than from barle The coarse bulk of the a l f a l f a prevents the steer from getting the amount o energy i t requires for optimum growth. This therefore explains why steers on a l f a l f a grow less and are less e f f i c i e n t i n u t i l i z i n g t h e i r feed for growth. For such steers to get the energy they need for optimum growth, they have to eat a l o t more. This therefore increases feed costs and re-s u l t s i n a higher feed cost per kilogram gain. There are, however, a v a r i e t y of reasons why some farmers should s t i l l s t i c k to feeding forages. The production of forage is a desirable component of good farming practice on most i f not a l l a g r i c u l t u r a l s o i l s 56 and unless the farmer can market his forage p r o f i t a b l y , he is not l i k e l y to be very interested i n forage production no matter how b e n e f i c i a l i t i s to his s o i l . Results from various experiments at the A g r i c u l t u r e Canada Melfort Research Station (1971, 1972, 1973) have shown that very good rates of gain can be obtained by feeding good q u a l i t y ground hay at up to 95% of the r a t i o n . However, in general these workers reported that feed costs were higher and dressing percentage lower as increasing levels of ground hay re-placed grain i n steer f i n i s h i n g r ations. In the present experiment, despite the fact that grain prices have increased considerably as compared to prices, of forages, i t has been shown that a farmer's best option would be to feed his steers on grains or 50%, grain-roughage r a t i o n i f he wants to cut down feed costs and get his animals to market as soon as possible. Not only did feed costs amount to an extra $395, $387 and $252 resp e c t i v e l y for groups of steers on rations 3, 4 and 5, but other costs, e s p e c i a l l y labour, i n t e r e s t on investment and depreciation on machinery would also r i s e considerably. Comparison of r i b eye area as predicted by the u l t r a s o n i c probe and area  of r i b eye as .measured on the carcass . A low c o r r e l a t i o n c o e f f i c i e n t (r = 0.27) was obtained when the e s t i -mate of r i b eye area by u l t r a s o n i c s was compared to the area of r i b eye as measured on the carcass by acetate paper tracings. For u l t r a s o n i c probe prediction, and measurement by the p l a s t i c g r i d method, the c o r r e l a t i o n c o e f f i c i e n t was also low (r = 0.30). A summary of the relationships reported i n the l i t e r a t u r e between ul t r a s o n i c and carcass measurements of r i b eye area in c a t t l e is presented i n Table 16. . ' 57 Table 16: Comparison of u l t r a s o n i c and carcass measurements of r i b eye area from the l i t e r a t u r e . Researcher No. of Animals Simple C o r r e l a t i o n of Rib Eye Area Stouffer and Wellington (1960) 54 0.49 I I 11 82 0.22 I I I I 16 0.85 Hedrick . et a l . (1962) 47 0.58 I I I I I I 28 0.89 . n n I I '57 0.78 Stouffer (1966) 82 0.22 McReynolds and Arthaud (1970) 10 0.95 G i l l i s et a l . (1973) 39 0.80 The c a t t l e involved in these and b u l l s . They also included younj; c o r r e l a t i o n s ; animals and involved h e i f e r s , steers r e l a t i v e l y older ones. Co r r e l a t i o n c o e f f i c i e n t s reported range from r = 0.22 (Stouffer and Wellington 1960, Stouffer 1966) to r = 0.95 (McReynolds and Arthaud 1970). More intermediate values are very common. Temple et. al_. (1965) have suggested that errors i n u l t r a s o n i c evalua-t i o n of l i v e c a t t l e r e s u l t i n g i n decreased accuracy i n p r e d i c t i n g lean and fat may be due to (1) animal v a r i a t i o n , (2) ti s s u e change during slaughter, (3) i n t e r p r e t a t i o n errors, (4) experience i n machine manipulation. Accord-ing to these workers, i n t e r p r e t a t i o n errors a r i s e from f a i l u r e to i d e n t i f y hide, f a s c i a l tissue, fat and muscle boundaries. Machine settings for proper penetration, damping of extraneous echoes and clearness of signals can only be done with experience. G i l l i s e t . a l . (1973) reported that with the Krautkramer USM 2F model (the model used i n this experiment) the r i b 58 eye area estimate was highly dependent on operator s k i l l . The u l t r a s o n i c determinations In this study were made by an experienced operator from the Production and Marketing Branch of the Canada Department of A g r i c u l t u r e . The low c o r r e l a t i o n c o e f f i c i e n t should not therefore have been due to any inexperience on the part of an operator. A factor which might have contributed to the low c o r r e l a t i o n co-e f f i c i e n t between predicted r i b eye area and the measured value, could be d i f f i c u l t y i n maintaining steers steady during the measurements. The animals were excitable and i n many cases measurements took quite some time. Under such circumstances the accuracy of the operator i n interpreta-t i o n might have been diminished. G i l l i s 'et' al_. (1973) i n - t h e i r work had reported a low c o r r e l a t i o n c o e f f i c i e n t of r = 0.32 for he i f e r s of average weight 375 kg and r = 0.80 for steers of average weight 454 kg. In t h i s t r i a l , groups of animals were slaughtered when the average pen weight ex-ceeded 400 kg or at 28 weeks. . Since quite a number of the-steers in this experiment were slaughtered at about 400 kg, i t may be possible to explain the low c o r r e l a t i o n c o e f f i c i e n t on the basis of low slaughter weight. If the r e s u l t observed by G i l l i s et. al_. (1973) i s explained on the basis that h e i f e r s have smaller muscling than steers, then i t is possible to postulate that within any species, the u l t r a s o n i c probe may not be. able to predict accurately the area of r i b eye muscle of animals.that do not have a very high degree of muscling. 59 SUMMARY AND GENERAL CONCLUSIONS Throughout the presentation of the r e s u l t s and discussion, i t has been the aim of this worker to consider the three main rations: (1) the a l l - b a r l e y r a t i o n (Ration 1); (2) the 50t barley r a t i o n (Ration 2); (3) the a l l - f o r a g e r a t i o n (Ration 3); i n respect of how they promoted growth, the e f f i c i e n c y with which they were u t i l i z e d i n the body for growth, and how they a f f e c t e d the composition and y i e l d of the steer carcass. The questions asked have been, "Which of these rations gave r i s e to the lowest feed cost/kg gain without adversely a f f e c t -ing the carcass y i e l d , and the carcass composition?" Also, "In the l i g h t of•the present i n f l a t i o n a r y prices of feed ingredients, which ones should an economy minded farmer adopt?" The a l l - f o r a g e r a t i o n had been shown to s i g n i f i c a n t l y reduce growth rate, to have the lowest feed e f f i c i e n c y and to have no adverse e f f e c t on carcass fat, r i b eye area or c u t a b i l i t y , but to s i g n i f i c a n t l y reduce the dressing, percentage of steers fed on i t . It also had the highest feed cost/kg gain ($1.36) and the steers on the. r a t i o n took an extra eight weeks to a t t a i n slaughter weight at a t o t a l extra feed cost of $395. The 507» barley r a t i o n was i n almost a l l respects s i m i l a r to the a l l -barley r a t i o n . There was no s i g n i f i c a n t d i f f e r e n c e between the two rations with regard to growth rate. The group feed e f f i c i e n c y of steers on both rations were s i m i l a r and high. Both rations had no adverse e f f e c t on average carcass fat, area of r i b eye muscle, or c u t a b i l i t y , but had a s i g -n i f i c a n t l y higher dressing percentage when compared to the a l l - f o r a g e r a t i o n . Steers on both rations were marketed at the same age and at about the same l i v e weight. The feed cost per kilogram body weight gain was $0.96 for the steers on the a l l - b a r l e y r a t i o n and $1.09: for those on the 50% barley r a t i o n . This is a 13.5%, difference in feed cost/kg gain between the two rations. On the basis of the s l i g h t l y lower feed cost/kg gain, the a l l - b a r l e y r a t i o n would be favoured. As regards the swtiched rations, the r e s u l t s indicated that s t a r t i n g steers on grains and f i n i s h i n g them on high q u a l i t y forage or v i c e versa did not a f f e c t the average growth rate, feed e f f i c i e n c y or the carcass composition of steers so treated. It was shown that regardless of the rat i o n , a p h y s i o l o g i c a l s h i f t of ingested energy from growth to fattening occurred at the 20th week with r e s u l t i n g f a l l i n the e f f i c i e n c y of feed u t i l i z a t i o n . It was also demonstrated that implantation of 36 mg Ralgro improved the rate of growth but not the carcass composition of steers so treated. There was no i n t e r a c t i o n between ingested energy l e v e l and the e f f e c t of the implantation. The anabolic e f f e c t of Ralgro tended to be depleted at 60 days, r a i s i n g the need for reimplantation i n long feeding experiments. It was shown that there was a poor c o r r e l a t i o n between the area of r i b eye as estimated by the u l t r a s o n i c probe and as measured on the carcass. Since a l l measurements were made by the sameCxperienced operator and there were no problems with the machine or l i n e voltage, i t was postulated that within each species, smaller or less-muscled animals were measured with less accuracy than larger or well-muscled animals. A l l r e s u l t s which are pertinent to the r a t i o n types used i n this study have been summarized in Table 11. 61 Table 17: Summary of res u l t s on r a t i o n treatment Ration Types Parameters ..1 2 3 4 5 I n i t i a l body weight (kg) 221.13 225.12 222.7 2 221.58 221.59 F i n a l body weight (kg) 429.56 415.95 434.09 440.22 453.50 No. of days on t r i a l 195 185 252 225. 219 Average d a i l y gain (kg) 1.07 1.03 0.84 . 0.97 •1.06 Feed e f f i c i e n c y (kg feed/kg gain) 7.01 8.29 11.29 .8.71 9.65 Feed cost/kg gain ($) 0.96 1.09 1.36 1.19 1.23 Average carcass fat (cm) .1.37 1.37 1.19 1.27 1.27 Rib eye area (sq cm) 63.06 63.03 63.74 63.68 66.58 Dressing "U 56.'42 55.74 54.31 54.00 55.44 62 Appendix Table"!: The composition of the mineral supplement Ground barley 616.89 kg Wheat shorts 90.72 kg Fat . 13.61 kg Salt (sodium chloride) 7.2.58 kg Dicalcium phosphate 45.36 kg Limestone 63.50 kg U.B.C. premix 4.54 .'kg Appendix Table 2: The composition of U.B.C. premix Viatmin A 140 g (325000 i.u./g) Vitamin D 2 120 g (80,000 i.u./g) CuS0 4 40 g C 0 S O 4 40 g MnSO.4 600 g ZnS0 4 1,000 g Prodine (17% iodine) 72 g Wheat shorts 2,528 g Appendix Table 3: The composition of the protein supplement Wheat shorts ' 433.19 kg Sunflower seeds 217.73 kg D i s t i l l e r s dried solubles 90.72 kg Urea 40.82 kg S a l t 36.29 kg Dicalcium phosphate 22.68 kg Limestone 31.75 kg Molasses 31.75 kg U.B.C. premix 2.27 kg BIBLIOGRAPHY Abraham, H.C., Carpenter, Z.L., King, G.T.and Butler, 0,D. (1968). Relation-ships of carcass weight, conformation and carcass measurements and the i r use' in pre d i c t i n g beef carcass c u t a b i l i t y . J . Anim. S c i . 27: ; 604. Aitken, J.N. and Crichton, J.A. (1956). The e f f e c t of hexosterol implanta-t i o n on growth and c e r t a i n carcass c h a r a c t e r i s t i c s of fattening steers. Br. J . Nut. 10:220. Al l e n , D.M., Merkel, R.A., Magee, W.T. and Nelson, R.H. (1968). V a r i a t i o n i n some beef carcass compositional c h a r a c t e r i s t i c s within and between selected weight and fat thickness range. J . Anim. S c i . 27:1239. Alsmeyer, R.H., Hiner, R.L. and Thornton, J.W. (1963). Ult r a s o n i c measure-ments of fat and muscle thickness of c a t t l e and swine. Annals New York Acad. S c i . 110:23. . Andrews, F.N., Beeson, W.M. and Johnson, F.D. (1954). The e f f e c t of s t i l -b e s t r o l, d i e n e s t r o l , testesterone and progesterone on the growth and fattening of beef steers. J . Anim. S c i . 13:99. Andrews, F.N., Stob, M. , Perry, M. and Beeson, W.M. (1956). The o r a l admini-s t r a t i o n of d i e t h y l s t i l b e s t r o l , d i e n e s t r o l and hexestrol for fattening calves. J . Anim. S c i . 15:685. Anon (1966a). A comparison of the growth of d i f f e r e n t types of c a t t l e for beef production. Report on major beef research project, Royal Smithfi e l d Club, London. A.O.A.C. (1970). O f f i c i a l Methods of Analysis, Assoc. O f f i c i a l A g r i c Chemists, n t h edition, 5.Washington, D.C. Arthaud, W.H., Adams, C.H.,.Jacobs, D.R. and Koch, R.M. (1969). Compari-son of carcass t r a i t s of b u l l s and steers. J. Anim. S c i . "28:742. Babatunde, .G.M., Fetuga, B.L. and Oyenuga, V.-A. (1971). The e f f e c t of varying the dietary c a l o r i e : protein rations on the performance c h a r a c t e r i s t i c s and carcass q u a l i t y of growing figs i n the tr o p i c s . Anim. Prod. 13:695. Bailey, CM. , Probert, L.L. and Bohman, V.R. (1966 ). The growth rate, feed u t i l i z a t i o n and body composition of.the young bulls and steers. J . Anim. S c i . 25:132. Balch, C.C. and Compling, R.C. (1962). Regulation of voluntary food i n -take i n ruminants. N u t r i t i o n Abstracts and Reviews 32:669. Bass, D.D., Palmer, ..A. Z. , Carpenter, J.W., Hentges, J.F., Wakeman, D.L., Koger, M. and Murphey, C.E. (1962). Indices of carcass quality and y i e l d grade i n feeder steers. J . Anim. S c i . 21_:978 Abs. Beeson, Win., Andrews,- F.N.y Stob, M., Perry, T.W. (1956 ). the eff e c t s of o r a l estrogens and androgens si n g l y and i n combination on yea r l i n g steers. Benedict, F.-G. and Ritzman, S. (1927). The metabolism of f a s t i n g steers. Carnegie I n s t i t u t e Publications, No. 377. Berg, R.T. and B u t t e r f i e l d , R.M. (1968). Growth patterns of bovine muscle, fat and bone, J . Anim. S c i . 27:611. Bir k e t t , R.J., Good, D.L. and Mackintosh, D.L. (1965). Relationship of various l i n e a r measurements and per cent y i e l d of trimmed cuts of beef carcasses. J. Anim. S c i . 24:16. Black, W.H.., Howe, P.E., Jones, J.M. and Keating, F.E. (1943). Fattening steers on milo i n the southern great p l a i n s . USDA Tech. B u l l . 847. Black, W.H., Semple, A„T.'and Lush, J.L. (1934). Beef production and quality as influenced by crossing Brahman with Hereford and Short-horn c a t t l e . USDA- Tech. B u l l . 417. Blaxter, K.L. and Wainmann, F.W. (1964). The u t i l i z a t i o n of the energy of d i f f e r e n t rations by sheep and c a t t l e for maintenance and for fattening. J. Agric. S c i . 63:113. Bloss, R.E., Northam, J.I . , Smith, L.W., Zimbleman, R.G. (1966). The effects of oral melengestrol acetate on the performance of feed-l o t c a t t l e . J . Anim. S c i . 25:1048. Bodwell, C.E., Harrington, G. and Pomeroy, R.W. (1959 ). A note on the measurement of eye muscle area i n beef carcass. Anim. Prod. 1:97. •' • . Boyd, E. (1933). The s p e c i f i c gravity of the human body. Human Biology 5:656. Brackelsberg, P.O., William, R.L. and Walters, L.E. (1967). Probing beef c a t t l e to predict carcass fatness. J . Anim. S c i . 26:713. Bradley, N.W., Cundiff, L.V., Kemp J.D. and Greathouse, T.R. (1966). Ef f e c t of sex and s i r e on performance and carcass t r a i t s of Hereford and Hereford Redpoll calves. J. Anim. S c i . 25:7 83. Branaman, G.A., Pearson, A.M., Magee, W.T., Griswold, R.M. and Brown, G.A. (1962). Comparison of the c u t a b i l i t y and e a t a b i l i t y of beef and dairy type c a t t l e . J . Anim. S c i . 21:321. Bray, R.W., Rupnow, E.H., Hanning, F.M., A l l e n , N.N. and Niedermeier, R.P. (1959). E f f e c t of feeding methods on veal production and carcass qu a l i t y 11: Carcass grades, l i v e r , hide, s p e c i f i c gravity, y i e l d , and chemical analysis of muscle. J . Anim. S c i . 18:732. Breidenstein, B.C., Breidenstein, >B.B., Gray, W.J., Garrigan, D.S. and Norton, H.W. (1963). Comparison of carcass c h a r a c t e r i s t i c s of steers and h e i f e r s . J. Anim. S c i . 22:113 Abs. .67 Brinks, J.A., Clark, R.T., K i e f f e r , N.-M. and Urick, J . J . (1964 ). Pre-d i c t i n g wholesale cuts of beef from l i n e a r measurements obtained by photogrammetry. J . Anim. S c i . 23:365. Brobeck, J.R. (1946). Mechanism of the development of obesity i n animals with hypothalamic lesions. P h y s i o l . Review 26:541. Brobeck, J.R. (1948). Food intake as a mechanism of temperature regula-t i o n . Yale J. B i o l , and Med. 20:545. Brobeck, J.R. (1955). Neural regulation of food intake. Annals New York Acad. S c i . 63:44. . Brown, C.J., H i l l i e r , J.C. and Whatley, J.A. (1951). S p e c i f i c gravity as a measure of the fat content of the pork carcass.. J . Anim. S c i . 10:97. Brown, R.G. (1970). An anabolic agent for ruminants. Journal of Amer. Vet. Med. Association 157:1538. Brundgardt, V.H. and Bray, R.W. (1963). Estimate of r e t a i l y i e l d of the four major cuts i n beef carcass. J . Anim. S c i . 22:177. Bucy, L. and Bennion, L.L. (1962). Concentrate-roughage le v e l s i n diets of fattening steers. J . Anim. S c i . 21:666 Abs. Burgess, T.D. and Lamming, G.E. (1960). The e f f e c t of d i e t h y l s t i l b e s t r o l , hexosterol and testesterohe on the growth rate and.carcass q u a l i t y of fattening beef steers. Anim. Prod. 2:93. Burroughs, W. Gulbertson, C.C„, K a s t e l i c , J . , Cheng, E. and Hale, W. (1954). The ef f e c t s of trace amounts of d i e t h y l s t i l b e s t r o l i n rations of fattening steers. Science 120:66. Busch, D.A., Dinkel, C.A., Schaeffer, D.E., Tuma, H.J. and Breidenstein, B.C. (1968). P r e d i c t i n g edible portions of beef carcass from r i b separation data. J . Anim. S c i . 27:35. B u t t e r f i e l d , R.M. (1962). P r e d i c t i o n of muscle content of steer carcasses. Nature 195:193. B u t t e r f i e l d , R.M. (1964). "Estimation of carcass composition: The anatomical approach." Tech. Conf. Carcass Composition and Appraisal of Meat Animals, C.S.I.R.D., Melbourne. C a h i l l , V.R., Kunkle, L.E., Klosterman, E.W., Deatherage, F.E. and Wierbicki, E. (1956). E f f e c t of d i e t h y l s t i l b e s t r o l implantation on carcass com-position, the weight of c e r t a i n endocrine glands of steers and b u l l s . J. Anim. S c i . 15:701. C a h i l l , V.R., Vanstaven, B. D., Kunkle, L.E.. and Klosterman, E.W. (1959). Eval-uation of carcasses s i r e d by long bodied and short bodied b u l l s . J. Anim. S c i . 18:1478 Abs. Callow, E.H. (1961). Comparative studies on meat, (7) A comparison between Hereford Dairy Shorthorn and F r i e s i a n steers on four l e v e l s of n u t r i -t i o n . J. Agric. S c i . 56:265. • Callow, E.H. (1962). The r e l a t i o n s h i p between the weight of a tissue i n a singl e j o i n t and the t o t a l weight of tissue i n a side of beef. Anim. Prod. 4:37. Campbell, D., Sonaker, H.H. and Esp l i n , A.L. (1959). The use of ul t r a s o n i c s to estimate the s i z e of longissimus d o r s i muscle i n sheep. J. Anim. S c i . 18:1483 Abs. Caprenter, J.W., Palmer, A. Z., Kirk, W.G.-, Peacock, F.M. and Koger, M. (1961). Slaughter and carcass c h a r a c t e r i s t i c s of Brahman and Brahman-Shorthorn crossbred steers. J. Anim. S c i . 20:336. C a r r o l l , F.D., Ellsworth, D.J. and Kroger, D. (1963). Compensatory carcass growth in steers following protein and energy r e s t r i c t i o n . J. Anim. S c i . 22:197. C a r r o l l , F.D., Nelson, D.D., Wolf, N.H. and Plange, G. (1964). Energy u t i l i -z ation i n h e i f e r s as aff e c t e d by a low protein i s o c a l o r i c d i e t . J. Anim. Sci.. 23: 758. 69 Cartwright, T.C.., Butler, O.D. and Cover, S. (1958). The r e l a t i o n s h i p of r a t i o n and inheritance to c e r t a i n production and carcass charac-t e r i s t i c s of y e a r l i n g steers. J. Anim. S c i . 17:540. Church, D.C. and Ralston, A.T. (1963). Comparison of performance of steer calves when fed ad l i b i t u m versus twice d a i l y i n i n d i v i d u a l s t a l l s . J. Anim. S c i . 22.: 708. Clawson, A.J.,' Blumer, N.T., Smart, W.W.G. and Barrick, E.R. (1962). Influence of energy-protein r a t i o on performance and carcass c h a r a c t e r i s t i c s of swine. J. Anim. S c i . 21:62. Clegg, M.T. and C a r r o l l , F.D. (1957). A comparison.of the method of administration of s t i l b e s t r o l on the growth and carcass character-i s t i c s of beef steers. J. Anim. S c i . 16:662. Clegg, M.T. and Cole, H.H. (1954). The a c t i o n of s t i l b e s t r o l on the growth response in ruminants. J. Anim. S c i . 13:108. Cobb, E.H. and Ovejera, A. (1965). P r e d i c t i n g y i e l d of trimmed r e t a i l cuts in beef carcasses. J. Anim. S c i . 24:592 Abs. Cole, J.W., Orme, L.E. and Kincaid,. C.M. (1960). Relationship of l o i n eye area, separable lean of various beef cuts and carcass measurements to t o t a l carcass lean in beef. J. Anim. S c i . 19:39. Cole, .J.W.., Ramsey, C.B. and Epley, R.H. (1962). S i m p l i f i e d method for predicting pounds of lean beef carcass. J. Anim. S c i . 21:355. Comline, R.S. and Titchen, D.A. (1960). Nervous control of the ruminant stomach. In "Digestive Physiology and N u t r i t i o n of the Ruminant." Ed. D. Lewis, page 10, Butterworth, London. Cooke, R. Lodge, G.A. and Lewis, D. (1972). Influence of energy and protein concentration i n the d i e t on the performance of growing pigs. 1: Response to protein intake on a high energy d i e t . Anim. Prod. 14:30. 70 Cooke, R., Lodge, G.A. and Lewis, D. (1972b). Influence of energy and protein concentration in the diet on the performance of growing pigs. Anim. Prod. 14:219. Corbin, J.E., Williamson, J.L., Geurin, H.B. and Wilcke, H.L. (1959). Photographic method of measuring l o i n eye area. J . Anim. S c i . 13:1485. Crown, R.M. and Damon, R.A. (1960). The value of the 12th r i b cut for measuring beef carcass y i e l d s and meat q u a l i t y . J . Anim. S c i . 19:109. . Cundiff, L.V., Moody, W.G., L i t t l e , J.E., Jones, B.M. and Bradley, N.W. (1967). P r e d i c t i n g beef carcass c u t a b i l i t y with l i v e animal measurements. J . Anim. S c i . 2_6:210 Abs. Damon, R.A., Crown, R.M., Singletary,, C.B. and McCraine, S.E. (1960). Carcass c h a r a c t e r i s t i c s of purebred and crossbred steers in the gulf coast region. J. Anim. S c i . 19:820. Davis, J.D. and Long, R.A. (1962). Ultrasonic and other methods of e s t i -mating muscling i n beef c a t t l e . J . Anim. S c i . 2_1:970 Abs. Davis, J.K., Long, R.A., S a f f l e , R.L., Warren, E.P..and Carmon, J.L. (1964). Use of ul t r a s o n i c s and v i s u a l appraisal to estimate t o t a l muscling i n beef c a t t l e . J. Anim. S c i . 23:638. Davis, J.K., Temple, R.S. and McCormick, W.C. (1966). A comparison of ul t r a s o n i c estimates of r i b eye area and fat thickness i n c a t t l e . J . Anim. S c i . 25:1087. Deans, R.J..,. Van A r s d e l l , W.J., Reinecke, E.P. and Bratzler, L.J. (1950). The e f f e c t of progesterone-estradiol implants and s t i l b e s t r o l feeding on feedlot performance and carcass c h a r a c t e r i s t i c s of steers. J . Anim. S c i . 15:1020. Dinusson, W.E., Andrews, F.N. and Beeson, W.M. (1950). The e f f e c t s of s t i l -b estrol and testosterone-thyroid a l t e r a t i o n and spaying on the growth and fattening of beef h e i f e r s . J . Anim. S c i . 9:321. Dodsworth, T.L. (1957). The use of hexosterol in beef production. Agric. Review 1. DuBose, L.E., Cartwright, T.C. and Cooper, R.J. (1967). P r e d i c t i n g steak and roast meat from production and carcass traits.. J . Anim. S c i . 26:688. Dumont, B.L. (1957). New methods of estimation of carcass q u a l i t y of l i v e pigs. E.A.A.P. meeting report No. 1957/930. F.A.D. meeting report No. 1957/16, page.23. Dumont, B.L. , Le Guelte, P. and Arnoux, J. (1961). S t a t i s t i c a l study of beef c a t t l e . (2) Estimating the weight of muscle.in Charolais. Ann. Zootechnie 10:321. Duncan, D.B. (1955). Mul t i p l e range and multiple F tests, Biometrics 11:1. Dyer, I.A., Rupnow, E.H. and Ham, W.E. (1960). E f f e c t s of l e v e l of 3,3-d i a l l y l h e x o s t e r o l on steer performance and carcass c h a r a c t e r i s t i c s . J . Anim. S c i . 1_9:1009. Elson, C.E., F u l l e r , W.A., Kline, E.A. and Hazel, L.N. (1963). E f f e c t of age on the growth of porcine muscle. J . Anim. S c i . 22:946. Embry, L.B. and Graber, C.R. (1969). Resorcylic acid lactone (RAL) implants for f i n i s h i n g steers and h e i f e r s . South Dakota State University, Beef C a t t l e F i e l d Day, page 31. England, D.C. and Taylor, N.O. (1959). E f f e c t of implanted testosterone on growth rate of weaner steers with and without previous s t i l b e s t r o l implantation. J . Anim. S c i . 1_8:1169 Abs. Epley, R i G . , Hedrick, H.B., Mies, W.L., Preston, R.L., Krause, G.F. and Thompson, G.B. (1971). E f f e c t s of d i g e s t i b l e protein to d i g e s t i b l e energy r a t i o diets on quantitative and q u a l i t a t i v e carcass composi-t i o n of beef. J. Anim. S c i . 33:355. E v e r i t t , G.C. (1964a). Component analysis of meat prod, using biopsy tech-niques. Tech. Conf. Carcass Comp. and Appraisal of Meat Animals, C.S.I.R.O., Melbourne, A u s t r a l i a . E v e r i t t , G.C. (1964b). Beef carcass appraisal by j o i n t i n g . Tech. Conf. Carcass Comp. and Appraisal of Meat Animals, C.S. I.R.O. , Melbourne, A u s t r a l i a . F i e l d , R.A. and Schoonover, C.O. (1967). Equations for comparing l i n g i s s i -mus d o r s i areas i n b u l l s of d i f f e r e n t weights.. J. Anim. S c i . 26: . 709. F i e l d , R.A., Schoonover, C.O. and Nelms, G.E. (1966). Relationship between carcass weight and muscle fat and bone i n b u l l carcasses. J. Anim. S c i . 25_:583 Abs. Fitzhugh, H.A., King, G.T., Orts, F.A., Carpenter, Z.A. and Butler, O.D. (1965b). Methods of pr e d i c t i n g the weight of boneless roast and steak meat-from e a s i l y obtained beef carcass measurements. J. Anim. S c i . 24:168. Garrett, W.N., Meyer, J.H. and Lofgreen, G.P. (1959a). An evaluation of the antipyrine d i l u t i o n technique for the determination of t o t a l body water i n ruminants. J. Anim. S c i . 18:116. Garrett, W.N., Meyer, J.H. and Lofgreen, G.P. (1959b). The comparative energy requirements of sheep and c a t t l e for maintenance and gain. J. Anim. S c i . 18:528. Garrett, W.N., Meyer, J.H., Lofgreen, G.P. and Dobie, J.B. (1961). E f f e c t of p e l l e t s i z e and composition on feedlot performance, carcass charac-t e r i s t i c s and rumen parakeratosis of fattening steers. J. Anim. S c i . 20:833. G i l l i s , W.A., Burgess, T.D., Usborne, W.R., Greiger, H. and Talbot, S. (1973). A comparison of two u l t r a s o n i c techniques for the measurement of fat thickness and r i b eye area i n c a t t l e . Can. J. Anim. S c i . 53:13. Glimp, H . A i and Cundiff, L.V. (1971). E f f e c t s of oral melengestrol acetate and a testosterone D i e t h y l s t i l b e s t r o l implant, breed and age on growth and carcass t r a i t s of beef h e i f e r s . J. Anim. S c i . 32:957. Good, D.L., Dahl G.M., Wearden, S. and Weseli, D.J. (1961). Relationship among l i v e and carcass c h a r a c t e r i s t i c s of selected slaughter steers. J. Anim. S c i . 20:698. Gottsch, A.H., Merkel, R.A. and Mackintosh, D.E. (1961). Relationship of muscie fat bone and some physical measurements to beef carcass cuta-b i l i t y . J . Anim. Sci.. 20:917 Abs. Guenther, J . J . , Pope, L.S., Odell, G.V. and Morrison, R.D. (1962). the growth and development of beef calves from weaning to slaughter weight with reference to the ef f e c t of plane of n u t r i t i o n . Okla. Agric. Expt, Sta. Misc. Publ. MP67, Page 20. Guenther, J . J . , Pope, L.S., Odell, G.V. and Morrison, R.D. (1965). Growth and development of the major carcass tissues i n beef calves from weaning to slaughter weight, with reference to the ef f e c t of plane of n u t r i t i o n . J. Anim. S c i . 24:1184. Guerin, H.B., Thompson, J . C , Wilcke, H.L. and Bethke, R.M. (1956). Oats as a c a t t l e fattening feed. J . Anim. S c i . 15:1251 Abs. Guerin, H.B., Williamson, J.L., Thompson, J . C , Wilcke, H.L. and Bethke, R.M. (1959). Rolled common barley serves as both grain and roughage for fattening steers. J . Anim. S c i . 1_8:1489 Abs. . Hale, W.H. and Ray, D.E. (1973). E f f i c a c y of oral e s t r a d i o l 17-B for growing and fattening steers. J . Anim. S c i . 37:1246. Hammond, J . (1957). Hormones i n meat production. Outlook on Ag r i c u l t u r e 1_:230. Hammond, J. and Appleton, A.B. (1932). Growth and development of mutton q u a l i t i e s i n the sheep. O l i v e r and Boyd, Edinburgh, Scotland. 74 Hankins, O.G. and Howe, P.E. (1946). Estimation of the composition of beef carcasses and cuts. U.S.D.A. Tech. B u l l . 926. Hankins, O.G., Knapp, B. and P h i l l i p s , R.W. (1943). The muscle-bone r a t i o as an index of merit i n beef and dual-purpose c a t t l e . J . Anim. S c i . 2_:42. Harte, F.J. (1967). The effects of plane of n u t r i t i o n i n the c a l f stage on growth rate, feed e f f i c i e n c y , carcass y i e l d and composition. Anim. Prod. _9:284 Abs. Haskins, B.R., Wise, M.B., Craig, H.B. and Barrick, E.R. (1967). Effects of levels of protein, sources of protein and an a n t i b i o t i c on performance, carcass c h a r a c t e r i s t i c s , rumen environment and l i v e r abscesses of steers fed all-concentrate rations. J. Anim. S c i . 26:430. Hawkins, D.R., Henderson, H.E. and Geasler, M.R. (1967 )„ Melengestrol acetate and s t i l b e s t r o l for f i n i s h i n g steers and h e i f e r calves. J. Anim. S c i . 26:1480 Abs. Hazel, L.N. and Kline, E.A. (1959). Ultrasonic measurement of fatness i n swine.. J. Anim. S c i . 18:815. Hedrick, H.B., Meyer, W.E., Alexander, M.A., Zobrisky, S.E. and Naumann, H.D. (1962). Estimation of r i b eye area and fat thickness of beef c a t t l e with u l t r a s o n i c s . J. Anim. S c i . 21:362. Henderson, D.W., G o l l , D.E. and Kline, E.A. (1966a). Relationship of muscling and f i n i s h measurements from three d i f f e r e n t groups of beef carcasses with carcass y i e l d . J. Anim. S c i . 25:325. Henderson, D.W., G o l l , D.E. and Kline, E.A. (1966b). Measures of carcass y i e l d and tenderness of two muscles i n four groups of beef carcasses. J. Anim. S c i . 25.: 329. . Henderson, D.W.., Go l l , D. E. , S tromer, M.H., Walter, M.J., Kline, E.A. and Rust, R.E. (1966c). E f f e c t s of d i f f e r e n t measurement techniques and operators on bovine longissimus d o r s i area. J . Anim. S c i . 25:334. 0 75 Henrickson, R.L., Pope, L.S. and Hendrickson, R.E. (1965). E f f e c t of rate of gain of fattening beef calves on carcass composition. J. Anim. S c i . " . 24:507. Hesselbarth, K. (1964). As quoted by Preson and W i l l i s (1970) i n ''Beef C a t t l e Production." Pergamon Press, New York. H i l l e r s , J . , Feryn, R. and Berry, B. (1968). Comparing three methods of measuring l o i n area. J . Anim. S c i . 27_:1107 Abs. Hogan, A.G. (1929). Retarded growth and mature siz e of beef steers. Mo. Agric. Exp. Sta. B u l l . 123. H u l l , J.L., Meyer, J.H. and Kromann, R. (1961). Influences of stocking rate on animal and forage production from i r r i g a t e d pasture. J . Anim. S c i . 20:46. Iwanaga, I.I. and Cobb, E.H. (1963). Relationship between y i e l d of trimmed r e t a i l cuts and c e r t a i n carcass c h a r a c t e r i s t i c s of beef c a t t l e . J . Anim. S c i . 22:827 Abs. Jordan, R.M. and Hanke, H.E. (1969). The e f f e c t of Ralgro and DES implants on lamb performance. Minnesota Sheep and Lamb Feeders Day, Page 15. Joubert, D i M . (1956). An analysis of factors influencing post-natal growth and development of the muscle- f i b r e . J. Agric. S c i . 47:49. Kauffman, R.G., Suess, G.G., Bray, R.W. and Scarth, R.D. (1968), Incidence of marbling of the bovine and porcine longissimus muscle. J . Anim. S c i . _27:9-69. Kay, M., Bowers, H.B. and McKiddle, G. (1968). The protein requirements of r a p i d l y growing steers. Anim. Prod. 10:37. Keith, T.B., Johnson, R.J. and Lehrer, W.P. (1955). Optimum r a t i o of con-centrates and roughage for steers as affected by corn s i l a g e and protein l e v e l . Idaho Agric. Exp. Sta. Res. B u l l . 32. 76 Kelly, R.F„, Fontenot, J.P., Graham, P.P., Wilkinson, W.S. and Kincaid, C.M. (1968). Estimates of carcass composition of beef c a t t l e fed at d i f f e r e n t planes of nutrition,, J . Anim. S c i . 27:620. Kennedy., G.C. (1953). The ro l e of depot fat. i n the hypothalamic control of food intake i n the rat. Proc. Roy. Soc. B 140:579. Kennick, W.H., Wallace, J.D., Raleigh, R.G. and Sather, L.A. (1965). A comparison of carcass and meat c h a r a c t e r i s t i c s of Hereford and Hereford-Charolais steers. J . Anim. S c i . 24:587. Kercher, C.J. (1960). Tr a n q u i l i z e r s f o r - f a t beef c a t t l e going to slaughter. J . Anim. S c i . 19:964. Kidwell, J.F. and McCormick, J.A. (1956). The influence of siz e and type on growth and development. J . Anim. S c i . 15:109. King, G.T., Carpenter, Z.L., Cunningham, N.L. and Orts, F.A. (1964). Cuta-b i l i t y of Santa Gertrudis cow carcasses. J . Anim. S c i . 23:853 Abs. Kirton, A.H. and Pearson, A.M. (1963). Comparison of methods of measuring potassium i n pork and lamb, and p r e d i c t i o n of their composition from sodium and potassium. J . Anim. S c i . 22:125. Klosterman, E.W., C a h i l l , V.R., Parker, C.F. and Harvey, W.R. (1965). A comparison of the Hereford and Charolais breeds and the i r crosses under two systems of management. Ohio Agric. Exp. Sta. Res. Summary ]_: 22. Klosterman, E.W„, Moxon, A.L. and C a h i l l , V.R. (1959). E f f e c t of s t i l b e s t r o l and amount of corn s i l a g e i n the r a t i o n on protein requirement of fattening steer calves. J . Anim. S c i . 18:1243. Kropf, D.H. (1959). Relationships of c e r t a i n muscle and bone c h a r a c t e r i s t i c s i n beef carcasses. J . Anim. S c i . 18:1154 Abs. Lamming, G.E. (1957). The use of hormones i n meat production. A g r i c u l t u r a l Progress (1957) 23:1-8. 7 7 Lamming, G.E. (1958).- Recent developments i n the use of growth stimulants in farm animals. Journal of Royal A g r i c u l t u r a l Society of England .• 119:41. Lamming, G.E., Swan, H. and Clarke, R.T. (1966). Studies on the n u t r i t i o n of ruminants. 1. Substit u t i o n of maize by milled barley straw i n a beef fattening diet and i t s e f f e c t on performance and carcass q u a l i t y . Anim. Prod. 8:303. Lauprecht, E., Scheper, J . and Schroder, J . (1957). As quoted by Preston and W i l l i s (1970) i n Intensive Beef Production, Pergamon Press, New York. Ledger, H.P. and Hutchinson, H.G. (1962). The value of the tenth r i b as a sample j o i n t for the estimation of lean, fat and bone i n carcasses of East A f r i c a n Zebu c a t t l e . J . Agric. S c i . 58:81. Lewis, R.W., Brungardt, V.H. and Bray, R.W. (1964 ), Estimating r e t a i l y i e l d from the four major wholesale cuts in h e i f e r carcasses. J. Anim. S c i . 23:861 Abs. Link, B.A., Carsens, R.G., Bray, R.W. and Kowalczyk, T.C. (1967). Fatty degeneration of bovine longissimus. J . Anim. S c i . 26:694. Magee, W.T., Merkel, R.A., Bratzler, L.J., Pearson, A.M. and Kemp, K.E. (1963). Relationship among performance t r a i t s of grade Hereford b u l l s . J . Anim. S c i . 27:13. Martin, E„M. and Lamming, G„E. (1958). The e f f e c t of hexosterol on the nucleic acid content of the anterior p i t u i t a r y gland of y e a r l i n g male sheep. Proc. N u t r i t i o n Society 17:XLVIII. Martin, T.G. (1968). Associations among estimators of beef carcass composi-ti o n . J . Anim. S c i . 2_7:1122 Abs. Marin, T.G.,'Drake, M.K., Garrigus, R.R., Perry, T.W. and Beeson,W.M.(1965). Carcass t r a i t s ' of Hereford and Charolais-Hereford h e i f e r s , J . Anim. S c i . 24:866 Abs. Martin, T.G., Howard, R.D., Lane, G.T., Judge, M..D. and Albright, J.L. (1966). E f f e c t of dietary regime on H o l s t e i n steer carcasses. J. Anim. S c i . 25:885 Abs. Martin, T.G. (1968). Associations among estimators of beef carcass composi-ti o n . J . Anim. S c i . 27_: 1122 'Abs. Mayer, J. (1955). The p h y s i o l o g i c a l basis of obesity and leanness. N u t r i -t i o n Abstracts and Reviews 25_: 597 ; 871. McCandish, A.C. (1923). Studies on the growth and n u t r i t i o n of d a i l y cows. V: Milk as the sole r a t i o n for calves. J . Dairy Science 6:54. McCrpskey, J.E.-, Pope, L.S., Stephens, D.F. and Waller, G. (1961). E f f e c t of p e l l e t i n g steer fattening rations of d i f f e r e n t concentrate to roughage r a t i o . J . Anim. S c i . 20:42. McMeekan, C P . (1940a). Growth and development of the pig with s p e c i a l ref-erence to carcass q u a l i t y c h a r a c t e r i s t i c s . J . Agric. S c i . 30:276. McMeekan, C.P. (1940b).- Growth and development in the pig with s p e c i a l reference to carcass quality c h a r a c t e r i s t i c s . I I : The influence of the plane of n u t r i t i o n on growth and development. J . Agric. S c i . 30:387. McReynolds, W.E. and Arthaud, V.H. (1970). Estimating fat depth and longissimus muscle area by use of ultrasonics i n beef c a t t l e . J. Anim. S c i . 30:186. . Mead, S.W. and Regan, W.M. (1931). Differences in rations devoid of roughages for calves. 1: The e f f e c t of a d d i t i o n of cod l i v e r o i l and a l f a l f a ash. J . Dairy Science 14:283. Melfort Research Sta t i o n (1971). New anabolic implant for steers compared to DES and Synovex-S using four feeding methods. 1971 Research Highlights, Research Station Melfort, Sask., page 16. 79 Melfort Research Station (1972). The e f f e c t of feeding various amounts.of ground hay i n s t a r t e r rations for feedlot steers and of implanting with DES Ralgro and Synovex S. 1972 Research Highlights, Research Station Melfort, Sask., page 16. Melfort Research Station (1973). E f f e c t of feeding various levels of ground hay in steer f i n i s h i n g rations. 1973 Research Highlights, Research Station Melfort, Sask., page 20. Meyer, B., Thomas, J., Buckely, R. and Cole, J.W. (1960a). The quality of grain f i n i s h e d and grass finis h e d beef as affected by ripening. Food Technology 14:4. Meyer, J.H., Hull, J.L., Weitkamp, W.H. and B o n i l l a , S. (1965). Compensa-tory growth responses of fattening steers following various low energy intake regimes on hay or i r r i g a t e d pasture. J . Anim. S c i . 24:29. Meyer, J.H., Lofgreen, G.P. and Garret, W.N. (1960b). A proposed method for removing sources of error i n beef c a t t l e feeding experiments. J. Anim. S c i . 1_9:1123. M i l l e r , J.C., Hedrick, H.B., Thompson, G.B., Fri e t a g , R.R., Meyer, W.E., Dyer, A.J. and Naumann, H.D. (1965). Factors a f f e c t i n g longissimus do r s i and subcutaneous fat measurements and indices of beef carcass cut out. Miss. Agric. Sta. Res. Bull..880. M i l l e r , K.P., Goodrich, R.D., Fredrick, E.C., Young, C.W., Meiske, J.C. and Cole, C.L. (1967). E f f e c t s of r a t i o s of concentrate and hay on performance and carcass q u a l i t y of Hol s t e i n steers. J . Anim. S c i , 26:926 Abs. Miller,- K.P., Meiske, J . C , Young, C.W. and Cole, C.L. (1966). A compari-son of d i f f e r e n t proportions of concentrate and hay-fed Holstein steers.. J. Anim. S c i . 2_5:1253 Abs. Moody, W.G. and Kemp, J.D. (1965). Separable components as related to beef r i b . J . Anim. S c i . 24:866 Abs. Moody, W.G. , Zobrisky, S.E., Ross, C.V. and Naumann-, .H. D. (1965). U l t r a -sonic estimates of fat thickness and longissimus d o r s i area i n lambs. J . Anim. S c i . 24:364. Morris, J.G. (1966). F i n i s h i n g steers on sorghum grain and sorghum s i l a g e . E f f e c t s of grain to roughage r a t i o , urea supplementation and hexo-s t e r o l implantation on rate of body weight gain, feed e f f i c i e n c y and carcass composition. J . Anim. S c i . 67:191. Moulton, C.R. (1923). Age and chemical development in mammals. J . B i o l . Chem. 57:79. Murphey, C.E., Hal let', D.K. , Tyler, W„E. and Pierce, J.C. (1960). Estimat-ing y i e l d s of r e t a i l cuts from beef carcasses. J . Anim. S c i 19:1240 Abs. Murry, J.A. (1922). Chemical composition of bodies. J . Agric. S c i . 12:103. Naumann, H. D. (1952). A recommended procedure for measuring and grading beef carcass evaluation. Proc. Reciprocal Meat Conference 5_:108. Nichols, J.R., Ziegle r , J.H., White, J.M., Kesler, E.M. and Watkins, T.L. (1964). Production and carcass c h a r a c t e r i s t i c s of H o l s t e i n - F r i e s i a n b u l l s and steers slaughtered at 800 or 1000 l b s . J . Dairy S c i . 47:179. O g l i v i e , M.L., F a l t i n , E .C, Hauser, E.R., Bray, R.W-i and Hoekstra (1960). E f f e c t of s t i l b e s t r o l i n a l t e r i n g carcass composition and feedlot performance of beef steers. J . Anim. S c i . 19:991. Orme, L.E., Cole, J.W. , Kincaid, CM. and Cooper. R.J. (I960). Predicting t o t a l carcass lean i n mature beef from weights of c e r t a i n e n t i r e muscles. J. Anim. S c i . 19:726. Orme, L.E., Pearson, A.M., Magee, W.T. and Bratzler, L.J. (1959). Relation-: ship of l i v e animal measurements to various carcass measurements in beef. J. Anim. S c i . 13:991. Panaretto, B.A. and T i l l , A.R. (1963). Body composition in vivo (2) The com-po s i t i o n of mature goats arid i t s r e l a t i o n s h i p to the antipyrine . t r i t i a t e d water and N-acetyl-4-aminoantipyrine spaces. Aust. J. Agric. Res. 14:926. Panier, C. (1957). Les ultrasons dan l a detamination de l ' e t a t d'engraisse-ment des pores. As quoted by Preston and W i l l i s (1970) in "Beef Cattle Production", Pergamon Press, New York. Perry, T.W., Beeson, W.M., Andrews, F.M. and Stob, M. (1955). The e f f e c t of oral administration of hormones on growth rate and deposition in the carcass of fattening steers. J. Anim. S c i . 14:329. Perry, T.W., Stob, M., Huber, D.A. and Peterson, R.C. (1970). E f f e c t of sub-cutaneous implantation of Resorcylic acid lactone on performance of growing and f i n i s h i n g beef c a t t l e . J. Anirm S c i . 31:789. Powell, W.E., Huffman, D.L. and Patterson, T.B. (1968 ). Quantitative e s t i -mates of beef carcass composition. J. Anim. S c i . 27_: 285 Abs. Preston, T.R. and Gee, I. (1957). E f f e c t of hexosterol on carcass composi-t i o n and e f f i c i e n c y of food u t i l i z a t i o n i n fattening lambs. Nature \ 179:247. . Preston, T.R. , Greenhalgh, I. and Macleod, N.A. (1960). The e f f e c t of hexo-s t e r o l on growth, carcass quality, endocrine and reproductive organs of ram, wether and female lambs. Anim. Prod. 3_:233. Preston, T.R., Whitelaw, F.G., Aitken, J.N., MacDearmid, A., and Charleson, . E.B. (1963). Intensive beef production 1: Performance of c a t t l e given complete ground d i e t s . Anim. Prod. .5:147. Preston, T.R. and W i l l i s , M.B. (1970). Intensive beef production. Perga-mon Press, New York. Price , J.E., Pearson, A.M. and Benne, E.J. (1957). S p e c i f i c gravity and chemical composition of the untrimmed ham as rela t e d to leanness of pork carcasses. J. Anim. S c i . 16:85. Price, J.F., Pearson, A.M. and Emerson, J.A. (1960a). Measurement of the cross-sectional area of the l o i n eye muscle i n l i v e swine by u l t r a -sonic r e f l e c t i o n s . J. Anim. S c i . 19:786. Price, J.F., Pearson, A.M., Pfost, H.B. and Deans, R.J. (1960b). Applica-t i o n of u l t r a s o n i c r e f l e c t i o n techniques i n evaluating fatness and leanness i n pigs. J. Anim. S c i . 19:381. Ralston, A.T., Kennick, W.H. and Taylor, N.O. (1962). E f f e c t of high con-centrate diets upon performance. J. Anim. S c i . 21:666 Abs. Ramsey, C.B., Cole, J.W. and Hobbs, C.J. (1962). Relation of beef carcass grades, proposed y i e l d grades and fat thickness to separable lean, fat and bone. J. Anim. S c i . 21:193. Ramsey, C.B., Cole, J.W., Temple, R.S. and Hobbs, C.S. (1966). P r e d i c t i o n of separable muscle i n carcasses of seven breeds of steers. J. Anim. S c i . 25:256. Abs. Rathburn, E.N. and Pace, N. (1945.). Determination of t o t a l body fat by means of body s p e c i f i c gravity. J. B i o l . Chem. 158:667. Raven, A.M., Robinson, K.L., Irwin, J.H.D. and Forbes, T.J. (1966). Beef production from b u l l s and steers. (2) The evaluation of carcasses of animals fed experimental high concentrate d i e t s . Rec. Agric. Res. j_5:129. Ray, M.L. and McBride, W.M. (1961). E f f e c t of Synovex-S on steer grains and carcass values. J. Anim. S c i . 20:400 Abs. Reid, J.T., Wellington, G.H. and Dunn, H.O. (1955). Some; re l a t i o n s h i p s amo the major chemical components of the bovine body and the i r applica-t i o n to n u t r i t i o n a l investigations. J. Dairy S c i . 38:1344. Richardson,.D., Smith, E.F., Baker, F.H. and Cox, R.F. (1961). E f f e c t s of roughage-concentrate r a t i o i n . c a t t l e fattening rations on grain, feed e f f i c i e n c y , digestion and carcass. J. Anim. S c i . 20:316. Riley, J.G., Hedrick, H.B., Thompson, G.B., Dyer, A.J. and Gehrke (1968). Comparison of methods for determining beef carcass composition. J. Anim. S c i . 27_: 1147 Abs. Riley, M.L., F i e l d , R.A. and Nelms, G.E. (1966). Comparison of two methods of measuring the area of longissimus dorsi muscle. J . Anim. S c i . 25:587 Abs. Schoonover, C.O. and Stratton, P.O. (1957). A photographic gri d used to measure r i b eye areas. J . Anim. S c i . 16:957. Skinner, P.E., Henrickson, R.L., Chambers, D. and Stephens, D.F. (1959). Carcass c h a r a c t e r i s t i c s of comprest and conventional type of Hereford. J . Anim. S c i . ,1_8:1469 Abs. Steel, R.G.D. and To r r i e , J.H. (1960). P r i n c i p l e s and procedures of s t a t i s -t i c s , McGraw H i l l Book Co., New.York. Stevenson, A.E. and DeLanger, H. (1960). Measurement of feed intake by grazing c a t t l e and sheep VII: Modified wet digestion method for determination of chromic oxide i n faeces. N.Z. J. Agric. Res. 3^:314. Stob, M., Baldwin, R.S., Tuite, J . , Andrews, F.N. and G i l l e t t e , K.G. (1962). I s o l a t i o n of an anabolic uterotropic compound from corn infected with Gibberella zeae. Nature 196:1318. Stouffer, J.R. (1966). Meat evaluation i n l i v e animals. Proc. Frontiers i n Food Research, Cornell University, Ithaca, New York. Stouffer, J.R., Wallentine, M.V. and Wellington, G.H. (1959). Ultrasonic measurement of fat thickness and l o i n eye area in l i v e c a t t l e and hogs. J . Anim. S c i . 1_8:1483 Abs. Stouffer, J.R., Wallentine, M.V. , Wellington, G.H. and Diekmann, A. (1961). Development and a p p l i c a t i o n of u l t r a s o n i c methods for measuring fat thickness and r i b eye area in c a t t l e and hogs. J . Anim. S c i . 20:759 Stouffer, J.R. and Wellington, G.H. (I960). Ultrasonics for evaluation of l i v e animal and carcass composition. Proc. 12th Res. Conf. Amer. Meat Inst. Found. Univ. of Chicago, Chicago, I l l i n o i s , page 81. Swan, H. and Lamming, G.E. (1967). Studies on the n u t r i t i o n of ruminants. II: The ef f e c t of l e v e l of crude f i b r e i n maize-based rations on the carcass composition of F r i e s i a n steers. Anim. Prod. 9_:203. Swinger, L.A., Gregory, K.E., Sumption, L.J. and Briedenstein, B.C. (1964). The importance of measuring cut out in c a t t l e . J . Anim. S c i . 2_3:854 Abs T a l l i s , G.M., Klosterman, E.W. and C a h i l l , V.R. (1959). Body measurements in r e l a t i o n to beef type and to c e r t a i n carcass c h a r a c t e r i s t i c s . J. Anim. S c i . j_8:108. Temple, R.S., Ramsey, C.B. and Patterson, T.B. (1965). Errors i n u l t r a -sonic evaluation of beef c a t t l e . J.Anim. S c i . 24:282. Temple, R.S., Stonaker, H.H., Howry, D., Posakony, G. and Hazaleus, A.M. (1956). Ultrasonic and conductivity methods for estimating fat thick-ness i n l i v e c a t t l e . Proc. West. Sec. 'Am. . Soc. Animal Prod. 7_:477. Thornton, J.W. and Hiner, R.L. (1965). Volume of beef round related to carcass composition. J . Anim. S c i . 24:301. Thurber, H.E., Strong, H.T. and Clegg, M.T. (1959). Relative value of d i f -ferent oestrogens and estrogen-steroid combinations upon growth in beef c a t t l e . J. Anim. S c i . 18:1176 Abs. Tulloh, N.M. (1961). Skin and s k i n f o l d thickness i n r e l a t i o n to depth of sub-cutaneous fat in beef c a t t l e . Aust. J . Exp. Agric. Anim. Husb. 1:27. Tuma, H.J., Henrickson, R.L., Odell, G.V„ and Stephens, D.E. (1963). Varia-t i o n in the physical and chemical c h a r a c t e r i s t i c s of the longissimus do r s i muscle from animals d i f f e r i n g in. age. J . Anim. S c i . 22:354. Tuma, H.J., Henrickson, R.L., Stephens, D.E. and Moore, R. (1962b). I n f l u -ence of marbling and animal age on factors associated with beef . quality. J. Anim. S c i . 21:848. Tuma, H.J., Venable, J.H., Wuthier, P.R. and Henrickson, R.L. (1962a). •Relationship of f i b r e diameter to tenderness and meatiness as i n -fluenced by bovine age. J . Anim. S c i . 21:33. Urban, W.E. and Hazel, L.N. (1965). Ultrasonic measurements of fattening rate i n swine. J. Anim. S c i . 24:830. Van Soest, P.J. (1963). Use of detergents i n the analysis of fibrous feeds. II: A rapid method for the determination of f i b r e and l i g n i n . J. AOAC 46:829. -Voisin, A. (1955). Behaviour and s a t i e t y of c a t t l e on pasture and in the s t a l l . N u t r i t i o n Abstracts and Reviews (1955) 25:1097. Waldman, R.C., Tyler, W.J. and Brungardt, V.H. (1971); Changes in the car-cass composition of Holstein steers associated with r a t i o n energy levels and growth. J. Anim. S c i . 32:611. Wallentine, M,V., Drain, J . J . , Wellington, G.H. and M i l l e r , J . I . (1961). Some eff e c t s on beef carcass from feeding s t i l b e s t r o l . J. Anim. S c i . 20:792. Warren, R.B., Arthaud, V.H., Adams, C.H. and Koch, R.M. (1959). Thermister thermometer for estimating fat thickness on l i v e beef c a t t l e . J. Anim. S c i . 18:1469 Abs. Waters, H.J. (1908). The capacity of animals to grow under adverse condi-tions. Soc. Prom. Agric. S c i . Proc. 29:71-96, Watkins, J.L., S h e r r i t t , G.W., Ziegler, J.H. (1967). P r e d i c t i n g body tissue c h a r a c t e r i s t i c s using u l t r a s o n i c techniques. J . Anim. S c i . 26:470. Watson, C.J., Davidson, W.M., Kennedy, J.W., Robinson, C.H. and Muir, G.W. (1948). . S c i e n t i f i c A g r i c u l t u r e 28:357. Webb,., R.J.', Cmarik, G. F. and Cate, H.A. (1957). The comparative effects of d i e t h y l s t i l b e s t r o l and progesterone e s t r a d i o l benzoate implant on fattening steers fed varying rations of concentrate and roughages. J. Anim. S c i . 16:1089 Abs. Weiss, R.L., Baumgardt, B.R., Barr, G. R. and Baumgardt, V.H. (1967). Some in fluences of rumen v o l a t i l e f a t t y acids upon carcass composition and performance i n growing and fattening steers. J . Anim. S c i . 26:389. 0 Wellington,' G.H., 'Re-id, J.J., Bratzler, L.J. and M i l l e r , . J.L. (1954). Body composition and.carcass changes of young c a t t l e . J„ Anim. S c i . 13:973 White, F.E. and Green, W.W. (1952). Relationships of measurement of l i v e animals to weight of wholesale cuts of'beef. J . Anim. S c i . 11:370. Willey, N.B., Riggs, J.K., Colby, R.W., Butler, O.D. and Reiser, R. (1952). The influence of l e v e l of fat energy i n the r a t i o n upon feedlot per-formance and carcass composition of fattening steers. J.'Anim. S c i . U:705. . W i l l i s , M.B., Preston, T.R., Martin, J.L. and Velazquez, M. (1968). Carcass composition of Brahman bu l l s fed high energy diets and slaughtered at d i f f e r e n t l i v e weights. Rev. Cubana Cienc. Agric. (English • edition) 2_:83. Wilson, L.L., .Dinkel, C.A., Ray, D.E. and Minyard, J.A. (1963). Beef carcass composition as influenced by d i e t h y l s t i l b e s ' t r o l . J . Anim. S c i . 22: . 699. Wilson, L.L., Dinkel, C.A., Tuma, H.J. and Minyard, J.A. (1964). L i v e animal p r e d i c t i o n of c u t a b i l i t y and other beef carcass characteris-t i c s by several judges. J . Anim. S c i . 23:1102. Winchester, C.F., Hiner, R.L. and Scarborough, V.C. (1957). Some eff e c t s on beef c a t t l e of protein and energy r e s t r i c t i o n . J. Anim. S c i . 16:426. Winchester, C.F. and Howe, P.E. (1955). Relative effects of continuous and interrupted growth on beef steers. U.S.D.A. Tech. B u l l . 1108. . 8 7 . Woods, W. (1962). E f f e c t of implantation followed by feeding of s t i l b e s t r o l on steer performance and carcass composition. J . Anim. S c i . 21:533. Woods, W. and Scholl, J.M. (1962). Substi t u t i o n of corn for forage i n the fattening r a t i o n of steers. J . Anim. S c i . 21:69. Woodward, R.R. , Rice, F.T., Queensberry, J.R., Hiner, R.L., Clark, R.T. and Willson, F.S. (1959). Relationship between measures of performance, body form and carcass q u a l i t y of beef c a t t l e . Mont. Agric. Exp. Sta. B u l l . 550. Yao, T.S., Dawson, W.M. and Cook, A.C. (1953). Relationship between meat production characters and body measurements in beef and milking Shorthorn steers. J . Anim. S c i . 12:775. Yeates, N.T. (1952). The quantitative d e f i n i t i o n of c a t t l e carcasses. Aust. J . of Agric. Res. 3_:68. ZInn, D.W., E l l i o t , H., Burnett, D. and Durham, R.M, (1961). Evaluation of U.S.D.A. beef grading methods. J . Anim. S c i . 20:922. 

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