The relationship between beef sire carcass EPD and progeny phenotype

Abstract

Carcass data from purebred steer (n = 207) and heifer (n = 66) progeny of 15 Charolais sires with carcass expected progeny differences (EPD) were used to quantify the relationship between sire EPD and progeny phenotype for hot carcass weight, fat thickness, muscle area, marbling score, and percent lean yield. The model included six slaughter date × sex subclasses, the linear effect of age at harvest (434 ± 18 d), and the appropriate sire EPD for each trait of interest. Differences of the regression coefficients from their theoretical expectation of one were tested using general linear models procedures. Sire EPD was positively (P < 0.0001) associated with progeny performance for hot carcass weight, fat thickness, muscle area, marbling score, and percent lean yield. For all traits, the regression coefficients were not different (P > 0.27) from one. Regression coefficients were 1.16 ± 0.41 kg, 1.27 ± 0.27 mm, 1.23 ± 0.23 cm2, 1.26 ± 0.23 score, and 0.84 ± 0.19% for hot carcass weight, fat thickness, muscle area, marbling score, and percent lean yield, respectively. These results suggest that carcass EPD for hot carcass weight, fat thickness, muscle area, marbling score, and percent lean yield were related to progeny differences at or near theoretical expectations. Selection for carcass merit using appropriate EPD would be expected to be successful. Key words: Beef cattle, carcass, expected progeny difference