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* School of Animal Sciences
,
Iberia Research Station
,
Reproductive Biology Center
Experimental Statistics Department, Louisiana State University Agricultural Center, Baton Rouge, 70803
Abstract
Steers and heifers were generated from Angus (A) and Belgian Blue (BB) sires mated to Brahman x Hereford (B x H) F1 cows to characterize their growth, carcass traits and longissimus shear force. A total of 120 B x H cows purchased from 2 herds and 35 bulls (14 A and 21 BB) produced calves during the 5-yr project. After the stocker phase, a representative sample of A- and BB-sired heifers and steers were transported to the Iberia Research Station to be fed a high concentrate diet. The remainder of the cattle was transported to a commercial feedlot facility. Each pen of cattle from the commercial feedlot was harvested when it was estimated that heifers and steers had 10 mm or greater fat. The BB-sired calves were heavier at birth (P < 0.01) than the A-sired calves. During the feedlot phase, the A-sired calves gained more weight (P < 0.05) than the BB-sired calves. The BB-sired calves had heavier (P < 0.01) carcass weights compared to the A-sired calves. This was due to a combination of a heavier final BW and higher dressing percent. Because of their greater muscling and less (P < 0.01) fat, carcasses from BB-sired calves had greater yield (P < 0.01) compared to carcasses from the A-sired calves. Carcasses from A-sired calves had a higher (P < 0.01) marbling score and higher (P < 0.01) USDA quality grade than carcasses from BB-sired calves. Tenderness, as measured by shear force of the steaks aged for 7 d, was similar for A-and BB-sired calves. However, steaks aged for 14 d from the A-sired calves had a lower shear (P < 0.01) compared to the steaks from the BB-sired calves. Steer calves were heavier (P < 0.01) at birth and weaning, and had more total gain in the feedlot, which resulted in a heavier final BW and HCW compared to the heifers. Steer carcasses also had higher marbling scores and quality grades while the heifer carcasses had larger LM area per 100 kg of carcass weight. In conclusion, the BB-sired calves had heavier carcass weights and greater cutability while the A-sired calves had a higher degree of marbling and higher quality grade, and steaks from carcasses of A-sired calves were more tender as measured by shear force at 14 d.
Key Words: beef breeds carcass composition gender growth tenderness
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