Effects of Tuli, Brahman, Angus, and Polled Hereford Sires on Carcass Traits of Steer Offspring

Abstract

Steer progeny (n = 122) of tropically adapted breeds [Tuli (TU) and Brahman (BR)] and temperate breeds [Angus (AN) and Hereford (HP)] was evaluated for carcass traits for 3yr. Multiparous British (Bt) cows were bred to each sire breed. Following weaning in the fall, steers were provided bermudagrass hay and a supplement until rye was available, which they grazed until March. Steers were fed for 100 to 110 d beginning in March. Live weight (LWT); hot carcass weight (HCW); longissimus area (LEA); percentage kidney, pelvic, and heart fat (KPH); actual fat thickness (ACT); adjusted fat thickness (ADJ); marbling score(MARB); maturity score(MAT); quality grade (QG); yield grade (YG); dressing percentage(DP); and LEA per unit of LWT (LEACWT) were collected. Data were analyzed by Proc MIXED using a model that included year, sire breed, and year × sire breed. Sire breed was a significant source of variation for all traits except LEA. The effect of year was significant for all traits, and year × sire breed was significant for only LWT. Least square means for LWT and HCW ranked the breeds similarly; the AN-sired calves (576 kg, 333 kg) and BR-sired calves (574 kg, 334 kg) were heavier than the TU-sired calves (526 kg, 304 kg), and the HP-sired calves had intermediate LWT and HCW (562 kg, 320 kg). The actual and adjusted fat means were larger (P<0.02) for AN-sired calves, HP-sired cavles were intermediate, and the BR- and TU-sired steers were similar with less external fat. The TU-sired calves had the largest LEA relative to weight. The AN- and TU-sired groups had a similar percentage grading Choice (26 and 21%, respectively), and the percentage grading Choice for the other two sire breed groups was 12% for BR and 18% for HP. In conclusion, carcass merit of TU-sired calves provides an acceptable alternative to BR-sired calves for producers desiring a tropically adapted sire breed, but they will likely produce smaller slaughter BW than BR sires if managed similarly.