E F F E C T OF SEX AND ENERGY L E V E L S

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1 76. E F F E C T OF SEX AND ENERGY L E V E L S ON BEEF CARCASS COMPO'S1 T l O N V I N C E N T H. ARTHAUD UNIVERSITY OF NEBRASKA Consumers are increasingly expressing a preference f o r beef c u t s with a high proportion of l e a n i n r e l a t i o n t o f a t. O u r expanding population w i l l demand an increasing supply of e d i b l e beef. T o s a t i s f y t h i s requirement, t h e most l o g i c a l s o l u t i o n i s t o convert a higher proport i o n of t h e beef produced i n t o e d i b l e l e a n m e a t and l e s s i n t o surplus f a t. Ration and sex, whether sex i s determined a t time of conception or as a result of c a s t r a t i o n after b i r t h, are two of t h e major sources of v a r i a t i o n t h a t a f f e c t t h e growth and development of t h e beef animal. Research has shown t h a t b i l l s w i l l g a i n more r a p i d l y and more e f f i c i e n t l y and y i e l d a higher percent of r e t a i l product t h a n steers o r h e i f e r s. Differences i n body composition have been measured and reported by t h e use of various methods. A summary of s t u d i e s where t o t a l e d i b l e product w a s one of t h e methods used i n measuring d i f f e r e n c e s influenced by sex i s shown i n table 1. There were s l i g h t d i f f e r e n c e s i n methods of trimming and boning, b u t all workers reported a higher y i e l d i n percent e d i b l e product from b u l l s t h a n steers o r h e i f e r s. The range of d i f f e r e n c e s i n e d i b l e product w a s 3.4 t o 7.9 percent g r e a t e r i n bulls than steers. A summary of carcass c u t a b i l i t y determined by obtaining t h e percent boneless, c l o s e l y trimmed cuts from t h e chuck, r i b, l o i n and round, as influenced by sex, i s presented i n t a b l e 2. These workers a l s o reported t h a t b u l l s have l e s s f a t than steers and h e i f e r s and consequently a higher y i e l d of t o t a l e d i b l e m e a t. The range of t h e reported d i f f e r e n c e s i n cuta b i l i t y w a s from 3.6 t o 6.4 percent g r e a t e r f o r b u l l s t h a n s t e e r s. S t e e r s had greater c u t a b i l i t y t h a n h e i f e r s i n all but one of t h e reported s t u d i e s. B u l l carcasses have been shown t o have l e s s f a t trim. Hedrick e t al. (1969) x4s;steers, reported a s i g n i f i c a n t (P4.05) d i f f e r e n c e i n f a t trim: b u l l s, %; h e i f e r s, 28.98%. Champagne e t al. (1969) found a s i g n i f i c a n t d i f Terence between percent separable f a t or trimmed carcass f a t between b u l l s and steers c a s t r a t e d a t f o u r ages ranging from b i r t h t o 9 months. These results i n d i c a t e t h a t b u l l s have a higher y i e l d of meat than s t e e r s and s t e e r s t h a n h e i f e r s when compared on a t o t a l carcass o r a major cut basis. Several i n v e s t i g a t o r s i n d i c a t e t h a t bulls have more trimmed bonel e s s chuck and round t h a n steers (Arthaud, 1969; Champagne e t al 1969; Field et al., 1964). Table 3 (Arthaud, 1969) shows t h e d i f f e r e n c e s i n k i l o grams of t h e major cuts of b u l l s and steers when adjusted t o a constant carcass weight. The d i f f e r e n c e s i n t o t a l r e t a i l product, round, chuck, and

2 77. ground beef were s i g n i f i c a n t a t P(O.01. There w a s no s i g n i f i c a n t d i f f e r e n c e i n l o i n o r r i b. Champagne e t al. (1969) reported i n a comparison of b u l l s with steers c a s t r a t e d at four ages t h a t a f t e r trimming and boning t h e b u l l s yielded more round, r i b and chuck. The d i f f e r e n c e s were s i g n i f i c a n t (RO.01). No d i f f e r e n c e s were present i n percent l o i n a f t e r trimming and boning. A s t u d 3 of t h e e f f e c t of sex, age and r a t i o n on beef q u a l i t y and composition i s being completed a t t h e University of Nebraska. The c a t t l e involved i n t h i s study were male Angus calves from two sources. Oneh a l f were c a s t r a t e d at weaning and f o u r animals from each source, sex and r a t i o n subgroup were sssigned t o each of f o u r age-at-slaughter groups (12, 15, 18 and 24 months). O f t h e s e f o u r assigned animals, two were s e l f - f e d a high energy r a t i o n and two were s e l f - f e d a low energy r a t i o n. The high energy r a t i o n was composed of 82.5% corn, 12.5% p e l l e t e d hay and 5% supplement. The low energy r a t i o n f e d t o t h e 1 2 month age group (165 days) and t o t h e 15 month age group t h e f i r s t 165 days was composed of 65% corn, 32.5% hay and 2.5% supplement. The low energy r a t i o n f e d t o t h e 15 month group t h e l a s t 80 days and t o t h e 18 month age group (140 days) and 24 month age group (149 days) was composed of 50% corn, 47.5% hay and 2.5% supplement. Wise (1969) reported some of t h e preliminary results from t h e f i r s t r e p l i c a t e of t h i s cooperative study. Q u a l i t y grade, as given i n table 4, i s s i g n i f i c a n t l y d i f f e r e n t (P4.01) f o r b u l l s and steers with b u l l s grading two-thirds of a grade lower t h a n s t e e r s. No s i g n i f i c a n t d i f f e r e n c e w a s found f o r q u a l i t y g r d e due t o r a t i o n s. McGinty and Marion (1965) fed b u l l s, s t e e r s and h e i f e r s low and medium concentrate r a t i o n s and reported t h a t b u l l s averaged t h e lowest i n both marbling score and c a r c a s s grade. Lean, f a t and bone separates of t h e 9-10-ll r i b were s i g n i f i c a n t l y influenced by sex as reported by Wise (1969), t a b l e 5. B u l l s had more separable l e a n and bone on both energy r a t i o n s t h a n s t e e r s. S t e e r s had higher amounts of separable f a t on both r a t i o n s t h a n bulls. Riggs e t al. (1967) f e d b u l l s, s t e e r s and h e i f e r s on two concentrate l e v e l s of 50 and 70 percent. They found t h a t bulls produced s i g n i f i c a n t l y more boneless c u t s t h a n s t e e r s or h e i f e r s and t h a t steers exceeded h e i f e r s. Bulls and aj-l c a t t l e f e d 50% concentrates showed l e s s f a t trim and f a t cover; higher y i e l d s of wholesale and trimmed boneless c u t s, l e a n trim and bone than s t e e r s and heifers and c a t t l e f e d 705 concentrates. Bailey e t al. (1966) reported t h a t carcasses of steers contained more (P<.Ol) f a t, less (P<.Ol) muscle, and l e s s (P<.05) bone t h a n b u l l carcasses a s measured by t h e composition of t h e 9-10-ll r i b. c- The d i f f e r e n c e i n composition when measured by s p e c i f i c g r a v i t y of t h e 9-10-ll r i b were similar t o those found through separation. Table 6 l i s t s t h e least square means f o r s p e c i f i c g r a v i t y. B u l l s had s i g n i f i c a n t l y (P<.Ol) higher s p e c i f i c g r a v i t y values t h a n s t e e r s. The higher sepasable f a t percent f o r s t e e r s would account f o r t h i s d i f f e r e n c e. This study i s i n cooperation with and supported i n p a r t by t h e Market Q u a l i t y Research Division, ARS, USDA, under Cooperative Agreement # (51).

3 78. Champagne e t al. (1964) found b u l l s t o have s i g n i f i c a n t l y higher s p e c i f i c g r a v i t y values than s t e e r s. Table 6 a l s o shows t h a t t h e mean s p e c i f i c g r a v i t y of t h e 9-10-IJ r i b 1. d o r s i f o r b u l l s w a s s i g n i f i c a n t l y (P<.05) higher t h a n s t e e r s i n d i c a t i n g t h e r e was less intramuscular f a t i n bulls. Table 7 l i s t s t h e least square means of some of t h e r i b charact e r i s t i c s f o r r a t i o n s ignoring sex. Table 7 shows t h a t t h e r e was no s i g n i f i c a n t d i f f e r e n c e due t o r a t i o n f o r separable l e a n. Bulls and s t e e r s f e d a high energy r a t i o n had more f a t and l e s s bone than those f e d a low energy r a t i o n. These d i f f e r e n c e s were s i g n i f i c a n t (Pc.01) A significant (P<.Ol) d i f f e r e n c e, t a b l e 7, w a s noted f o r t h e s p e c i f i c g r a v i t y of t h e r i b. This d i f f e r e n c e can be accounted f o r by t h e higher separable f a t percent f o r t h e c a t t l e fed a high energy r a t i o n. No s i g n i f i c a n t (Pc.05) d i f f e r e n c e was found f o r s p e c i f i c g r a v i t y of t h e r i b 1. d o r s i. This s u b s t a n t i a t e s t h e f i n d i n g of no d i f f e r e n c e i n q u a l i t y grade due t o r at ion.. Chemical a n a l y s i s of a c r o s s s e c t i o n of t h e r i b cut taken a t t h e 8 t h r i b, reported i n t a b l e 8, showed a s i g n i f i c a n t d i f f e r e n c e (R.01) of 9.7% g r e a t e r e t h e r extract, moisture-free b a s i s, f o r s t e e r s t h a n b u l l s. There w a s no s i g n i f i c a n t d i f f e r e n c e i n e t h e r e x t r a c t due t o r a t i o n. B u l l s had a s i g n i f i c a n t l y (P<.Ol) higher percent moisture t h a n s t e e r s. Arthaud (1969) reported t h a t a chemical a n a l y s i s of a 1 cm t h i c k untrimmed but boneless c u t at t h e 1 2 t h r i b indicated b u l l s had Ilk less f a t and 11% more p r o t e i n t h a n comparable s t e e r c u t s. This review of t h e e f f e c t of sex and energy l e v e l s on carcass composition shows t h a t b u l l s do produce a c w c a s s with a higher proportion of l e a n e d i b l e meat and less f a t t h a n s t e e r s. This r e s u l t s i n t h e more e f f i c i e n t production of e d i b l e beef f o r our expanding population. BIBLIOGRAPHY Arthaud, V. H., C. H. Adams, D. R. Jacobs and R. M. Koch Comparison of c a r c a s s t r a i t s of b u l l s and s t e e r s. J. h i m. Sei. 28:742. Arthaud, V. H. and C. H. Adams E f f e c t of sex on production and c a r c a s s t r a i t s. University of' Nebraska Beef C a t t l e Progress Report. p. 4. Bailey, C. M., C. L. Probert and V. R. Boham Growth r a t e, feed u t i l i z a t i o n and body composition of young b u l l s and s t e e r s. J. h i m. Sei. 25:132. Briedenstein, B. C., B. B. Briedenstein, W. J. Gray, D. S. Garrigan and H. W. Norton Comparison of carcass c h a r a c t e r i s t i c s of s t e e r s and h e i f e r s. J. h i m. Sci. 22:lll3. (Abstr.). Champagne, J. R., J. W. Carpenter, J. F. Hentges, A. Z. Palmer and T. J. Cunha E f f e c t s of age a t c a s t r a t i o n on f e e d l o t performance and carcass c h m a c t e r i s t i c s of b u l l s and steers. J. him. Sci. 23:859.

4 79. Field, R. A., C. 0. Schoonover and G. E. Nelms Performance data, carcass yield and consumer acceptance of retail cuts from steers and bulls. Wyo. Agr. Exp. Sta. Bul Hedrick, H. B Bovine growth and composition. Res. Bul NC Regional Pub. No Mo. Agr. Exp. Sta. Hedrick, H. B., G. B. Thompson and G. F. Krause Comparison of feed lot performance and carcass characteristics of half-sib bulls, steers and heifers. J. Anim. Sci. 29:687. nosterman, Earle W., L. E. Kunkle, Paul Gerlough and V. R. Cahill The effect of age of castration upon rate and economy of gain and carcass qudity of beef calves. J. him. Sci. 13:817. Riggs, J. K., B. E. Conrad, P. T. Marion and J. H. Allen Young bulls, steers and heifers for slaughter beef production. J. him. Sci. 26:Zll. Wierbicki, E., V. R. Cahill, L. E. Kunkle, E. W. Klosterman and F. E. Deatherage Effect of castration on biochemistry and quality of beef. J. Agr. Food Chem. 3:244. Wise, J. W Chemical and physical characteristics of beef ribs as influenced by sex, age at slaughter and ration. M. S. Thesis, University of Nebraska. Wythe, L. D., Jr., P. T. Marion, B. E. Conrad and E. M. Neal Young bulls versus steers for beef production. Texas Agr. Exp. Sta. and Mech. College of Texas Misc. Pub. 670:94.

5 80. TABU3 1 Comparison of Percent Edible Portion of B u l l s, S t e e r s and Heifers Percent Edible Portion Bulls Steers Heifers Reference Arthaud e t al. Briedenstein e t al. 'Champagne e t al. - Hedrick e t al. KLosteman e t al. We i r b i c k i (1969) (1963) 62.9 (1964) e 2 (1969) 74.9 (1954) (1955) TABm 2 Comparison of C u t a b i l i t y Expressed as Percent Yield of Trimmed, Boneless Chuck, Rib, Loin and Round of Bulls, S t e e r s and Heifers Carcass C u t a b i l i t y Steers Heifers BuUs Reference Arthaud and Adams Hedrick e t d. - c Hedrick e t al. Wythe (1964) (1968) ( 19 69) (1963)

6 81. TABU 3 Trait Means of Bulls, Steers and Their Differences Adjusted to a Comon Carcass Weight of 235 Kg. Trait Bulls Steers Difference a Total retail product, kg Boneless retail cuts: Rmd, kg. Loin, kg. Rib, kg. Chuck, kg. Ground beef, kg. Fat thickness, cm ll.7 U a All differences between bulls and steers, except rib and loin weight were significant at KO. 01. TABLE 4 Least Square Means for Quality Grade" Me anc Rationd High Energy Low Energy Bulls Quality Gradeb Steers a Data from Wise (1969). 10 = Good; U = Good+; 12 = Choice-; 13 = Choice Significant differences (P4.01) in quality grade were found for sex. d NO significant differences were noted in qudity grade for ration within sex.

7 82 Least Square Means for 9-10-ll Rib Separable Lean, Fat and Bonea b Mean Ration b Separable Lean, $ Sepmable Fat, 5 Separable Bone, $ Bulls Steers Bulls Steers Bulls Steers High Energy Low Energy a Data from Wise (1969). Percent lean, fat and bone were significantly (P<.Ol) influenced by sex and ration except for lean where no significant difference (P<.05) due to ration was noted. TABLE 6 Least Square Means for Specific Gravity of Rib and 9-10-ll Rib L. Dorsi" Me an b RationC High Energy Low Energy Specific Gravity Specific Gravity' 9-10-ll Rib 9-10-ll Rib L. Dorsi Bulls Steers Bulls Steers a Data from Wise (1969). Significant differences (P<.Ol) for specific gravity of the rib and 1. dorsi for sex were noted. A significant difference (P4.01) due to ration was noted for rib specific gravity, but the difference due to ration for specific gravity of the 1. dorsi muscle was not significant (P<.05).

8 83. TABLE 7 Least Square Means f o r Rib C h a r a c t e r i s t i c s " T r a i t or Measure High Energy Separable leanc Separable f a t C Separable bonec S p e c i f i c g r a v i t yc S p e c i f i c g r a v i t y 1. d o r s i C Fat thickness 12th r i b k k k cm Ration' Low Energy a Data from Wise (1969). No s i g n i f i c a n t (Pc.05) d i f f e r e n c e s due t o r a t i o n were found f o r separable lean or s p e c i f i c g r a v i t y of t h e 1. d o r s i, but s i g n i f i c a n t (X.01) d i f f e r e n c e s due t o r a t i o n were found f o r separable f a t and bone and s p e c i f i c g r a v i t y of t h e r i b. -_c_ ' 9-lOzll r i b. Least Square Means f o r 8 t h R i b Ether E x t r a c t on a Moisture Free Basis and 8 t h R i b Moisture" M e anb e Ration' High Energy Low Energy a Data from Wise (1969). b Percent e t h e r extract (MFB) and moisture were s i g n i f i c a n t l y (P<.Ol) af'fected by sex No s i g n i f i c a n t difference (PG05) w a s found f o r r a t i o n s on e t h e r e x t r a c t (ME%)o r moisture.

9 84 /. ' L. E. WALTEZS: Thank you very much, Vince, f o r t h a t i n t e r e s t i n g p r e s e n t a t i o n of work t h a t i s unique i n t h a t t h e r e a r e many d i f f e r e n t energy l e v e l s involved and t h a t perhaps may stimulate some thoughts from t h e people i n t h i s group r e l a t i v e t o t h i s p a r t i c u l a r type of work i n t h e breeding of b u l l s. O u r next paper d e a l s with t h e "Influence of Mechanical and PharmacologicaJ. Stimuli on Intra-muscular Fat Disposition." To present t h i s paper I am happy t o introduce D r. J. A. Marchello, from t h e University of Arizona. John. if############