Effects of steer breed composition on feedlot performance and carcass traits1

Records of steers (n = 3,554) of known breed composition were used to assess the effect of breed composition on feedlot performance and carcass traits. Feedlot ADG was greater (P ≤ 0.01) for Angus and Red Angus than for Brangus and Polled Hereford steers. Longissimus muscle area ranged from 81.6 cm2 for Beefmaster carcasses to 85.7 cm2 for Red Angus carcasses and was affected by breed (P < 0.01). Marbling score was greatest (P = 0.03) in Angus carcasses and greater (P < 0.05) in Brangus than in Polled Hereford and Beefmaster carcasses. All following results are relative to a British base. Direct additive effects for backfat thickness in Continental (P < 0.01), American (P < 0.01), and Zebu (P < 0.05) breeds were − 0.6, − 0.2, and − 0.1 cm. Marbling score and USDA QG direct additive effects (P < 0.01) were large negative values for American, Continental, and Zebu. The Continental direct additive effect (P < 0.01) for LM area was 9.7 cm2 . Calculated YG direct additive effects (P < 0.01) were − 0.2 and − 1.0 for American and Continental breeds, respectively. Direct heterosis effects (P < 0.01) in British × American steers were present for ADG and marbling score, whereas Continental crosses tended to exhibit direct heterosis effects (P < 0.05) for LM area and backfat thickness. Steer breed composition influenced finishing performance and carcass traits. This information is important for breed selection, finishing, and marketing decisions.