Authors : Z. Wang , L. A. Goonewardene , R. C. Yang , M. A. Price , M. Makarechian , J. Knapp , E. K. Okine and R. T. Berg
Abstract: Production records over a twenty-five year period (n=6047) from three synthetic beef lines, Beef Synthetic 1 (BS1), Beef Synthetic 2 (BS2) and Dairy Beef Synthetic (DBS), at the University of Alberta Kinsella Research Station were analyzed to determine genetic parameters and genetic trends for birth weight (BW) and pre-weaning gain to 200-d (WG). The lines were selected for high fertility in females, high pre- and post-weaning gain in males and against high BW in both sexes. The Multiple Traits Derivative Free Restricted Maximum Likelihood (MTDFREML) was used to estimate (co) variance components, direct (h2d) and maternal (h2m) heritability, direct (rgd) and maternal (rgm) genetic correlations. The h2d and h2m for BW were 0.45 and 0.10 respectively, and the h2d and h2m for WG were 0.19 and 0.12 respectively. The rgd and rgm between BW and WG was 0.32 and 0.18 respectively. In BS1, the average direct and maternal breeding value change for BW was 0.08 and 0.00kg yr-1 respectively, and for WG was 0.29 and 0.12 kg yr-1 respectively. Genetic trends similar to BS1 were observed in the BS2 and DBS lines for BW only. Under commercial situations, by phenotypic selection alone it is possible to improve WG with little or no increase in BW.
Z. Wang , L. A. Goonewardene , R. C. Yang , M. A. Price , M. Makarechian , J. Knapp , E. K. Okine and R. T. Berg , 2005. Estimation of Genetic Parameters and Trends in Pre-Weaning Traits of Beef Lines Subject to Phenotypic Selection . Journal of Animal and Veterinary Advances, 4: 202-209.