Relationship of Growth Stimulants and Breed Groups on Carcass Characteristics and Palatability of Young Bulls

Abstract

Ninety-six young bulls, 32 of each of three breed groups (Hereford, Hereford × Angus and Charolais-cross), were assigned randomly (within breed) to a control or to one of three growth stimulant implant treatments-Compudose, Ralgro or Synovex-and fed a high concentrate diet for 118 d. Bulls were initially implanted on d 1 of test; bulls in the Ralgro and Synovex groups were reimplanted on d 75. Charolais-cross bulls had less (P<.05) subcutaneous fat and larger (P<.05) longissimus muscle areas, which resulted in lower (P<.05) numerical yield grades than did either the Hereford or Hereford × Angus bulls. Synovex-implanted bulls had higher (P<.05) adjusted fat thickness at the 12th rib and higher (P<.05) numerical yield grades than did bulls that were not implanted or those that were implanted with Ralgro, while carcasses from the Compudose-implanted bulls were intermediate in adjusted fatness and yield grade to the other groups. For the Hereford breed group, all nonimplanted bulls were classed as "bullock" carcasses. Implanted Hereford bulls more often (P<.05) produced carcasses that were classed as "steers." Neither growth stimulant nor breed group had any effect (P<.05) on palatability traits, shear force or cooking loss for loin steaks. The USDA sex class designations did denote differences (P<.05) in muscle fiber tenderness, overall tenderness, overall palatability and shear force values.