The effects of two shipping treatments on the carcass characteristics of bulls implanted with zeranol and unimplanted steers

• Published in: Journal of animal science Vol. 62; no. 6; p. 1602
• Main Authors: Jones, S.D.M, Newman, J.A, Tong, A.K.W, Martin, A.H, Robertson, W.M
• Format: Journal Article
• Language: English
• Published: United States 01.06.1986
• Subjects: ANABOLICOS; ANABOLICS; ANABOLISANT; Animals; Body Composition - drug effects; BOEUF; BUEY; BULLOCKS; BULLS; CALIDAD; CANAL DE LA RES; CARCASS COMPOSITION; CARCASSE; CARCASSES; Cattle - physiology; COMPOSICION DE LA CANAL; COMPOSITION DE LA CARCASSE; IMPLANTACION; IMPLANTATION; Male; Meat - analysis; QUALITE; QUALITY; Resorcinols - pharmacology; STRESS; Stress, Physiological - veterinary; TAUREAU; TORO; TRANSPORT; TRANSPORTE; Zeranol - pharmacology
• ISSN: 0021-8812; 1525-3163
• DOI: 10.2527/jas1986.6261602x

A total of 144 male crossbred calves were allocated to four management treatments (bulls; steers; bulls implanted with zeranol at 100 d of age and re-implanted at 69, 93 and 56 d thereafter; bulls implanted with zeranol at 168 d of age and re-implanted at 93 and 56 d thereafter), and two pre-slaughter shipping treatments (minimum pre-slaughter stress with cattle shipped and slaughtered within 4 h of leaving the feedlot pen; moderate pre-slaughter stress with cattle mixed, trucked 160 km and slaughtered up to 24 h of leaving the feedlot pen) in a 4 X 2 factorial arrangement. Management treatment had no significant effect on carcass pH (45 min), carcass muscle temperature (45 min), or peak shear-force of cooked longissimus muscle. Steers had significantly lower dressing percentage, warm-carcass weight, hide weight and carcass-lean content, but higher marbling score, fat thickness and intramuscular-fat content than all treatments with bulls. Minimum pre-slaughter stress resulted in significantly lower dressing percentage, warm-carcass weight, and carcass pH (45 min), but generally had no effect on carcass tissue-yield measurements compared with the moderate stress treatment. Implanted bulls produced carcasses with significantly darker meat, higher 24-h pH and lower meat expressible juice than bulls and castrates for the moderate pre-slaughter stress treatment. These results provide evidence that zeranol implantation in bulls had a minor influence on carcass characteristics, and did not reduce the incidence of dark-cutting carcasses in young bulls subjected to moderate pre-slaughter shipping stress.