Characterization of biological types of cattle (Cycle VIII): carcass, yield, and longissimus palatability traits.

The objective of this experiment was to evaluate alternative sources of tropically adapted cattle germplasm and compare them with Angus- (AN) and Hereford- (HE) sired steers. Carcass, yield, and longissimus thoracis palatability traits from F(1) steers (n = 621) obtained from mating AN and MARC III cows to HE, AN, Brangus (BR), Beefmaster (BM), Bonsmara (BO), or Romosinuano (RO) sires were compared. Data were adjusted to constant age (426 d), carcass weight (340 kg), fat thickness (1.0 cm), fat trim percentage (25%), and marbling (Small(00)) endpoints. For Warner-Bratzler and slice shear force and trained and untrained sensory panel traits, data were obtained on LM from ribeye steaks stored at 2 degrees C for 14 or 15 d postmortem. The following comparisons were from the age-constant endpoint. Carcasses from BM-, AN-, and BR-sired steers (358, 355, and 351 kg, respectively) were heavier (P < 0.05) than carcasses from steers from HE (343 kg) and BO (331 kg) sires; RO-sired steers (318 kg) had the lightest (P < 0.05) carcasses. Adjusted fat thicknesses for AN- and BM-sired steers (1.3 and 1.2 cm, respectively) were greater (P < 0.05) than for steers from BR (1.0 cm) and BO (0.9 cm) sires; RO-sired steers (0.8 cm) had the least fat thickness. Longissimus areas were larger (P < 0.05) for BO- and BR-sired steers (84.4 and 84.1 cm(2), respectively) than for BM- and HE-sired steers (80.8 and 80.2 cm(2), respectively). A greater (P < 0.05) percentage of carcasses from AN-sired steers graded USDA Choice (69%) than other sire breeds (17 to 47%) except HE (52%). Carcass yield of boneless, totally trimmed retail product was least (P < 0.05) for AN-sired steers (60.1%) and greatest (P < 0.05) for RO- and BO-sired steers (64.4 to 63.5%). Considering all measurements, AN LM tended to be more tender and BM LM tended to be least tender. American composite breeds BM and BR were heavier, fatter, lesser yielding, with similar marbling scores but less tender LM than BO and RO. Angus carcasses were similar in size, fatter, lesser yielding, with more marbling and more tender LM compared with BM and BR. Bonsmara and RO provide tropically adapted germplasm and produce carcasses that are lighter, leaner, greater yielding, with similar marbling and LM that tend to be more tender than carcasses from BM and BR.