|Van vleck, Lloyd|
Submitted to: Midwestern Section of the American Society of Animal Science
Publication Type: Abstract only
Publication Acceptance Date: 11/1/2004
Publication Date: 3/1/2005
Citation: Stroh, J.D., Vuorisalmi, M.L., Cundiff, L.V., Van Vleck, L.D. 2005. Indirect estimation of genetic trends for carcass traits in beef cattle [abstract]. Midwestern Section of the American Society of Animal Science 83(2):40. Interpretive Summary: No interpretive summary is required.
Technical Abstract: Records of carcass traits collected on steer progeny (n = 650) of 17 breeds of sire at USMARC and EPD from breed associations for birth, weaning and yearling weights of their sires were used to regress the carcass measurements of progeny at USMARC on sire EPD for the three weight traits. The model used also included fixed effects of sire line, dam line, age of dam and birth year. Dam and residual were random effects. The regression coefficients were then used to estimate genetic change in each carcass trait based on the genetic trends expressed by average EPD by year of birth for the weight traits as reported by the breed associations. Estimates of variance and covariance components with single- and two-trait analyses were obtained as a check on the regression coefficients using the MTDFREML programs. Genetic trends were estimated for 11 carcass traits for Angus, Charolais, Hereford, Limousin, Maine-Anjou, Red Angus, Shorthorn, and Simmental breeds. Results show that the regression equations would predict genetic change for carcass traits that are generally highly correlated with weight traits but only if change has occurred in the breed for the weight traits. Little change would be predicted for carcass traits with little or no correlation with weight traits even if change in the breed has occurred for the weight traits. As examples, the trio of multiple regression coefficients (phenotypic standard deviations of carcass traits per kg of EPD for birth, weaning, and yearling weights) 1) were -0.0056, -0.0063, and 0.0035 for fat thickness at 13th rib, 2) were 0.0070, 0.0006, and 0.0028 for estimated retail product, and 3) were -0.0011, -0.0053, and 0.0033 for marbling score.