Genetic parameters of beef traits of Limousin and Charolais progeny-tested AI sires.
Genetic parameters among progeny traits were estimated using multi-trait restricted estimation of maximum likelihood (REML) analyses in Charolais and Limousin cattle. The expected decrease in genetic variability among progeny traits due to the selection of sires was not observed. It is concluded that this selection was not a strict truncation. Heritabilities of traits measured on progeny were moderate for growth traits, morphology and body fat scores (from 0.14 to 0.38) and slightly higher for dressing percentage and carcass fatness score (0.50 and 0.44, respectively). Genetic correlations among progeny traits depended on trait, selection programme and breed. Carcass weight and morphology were highly genetically linked to corresponding live traits (live weight and conformation respectively); it is concluded that these traits could be easily improved through indirect selection, in contrast to carcass fatness which had only a small genetic correlation with live traits.