ESTIMATION OF GENETIC-PARAMETERS FOR GROWTH, FEED CONSUMPTION, AND CONFORMATION TRAITS FOR DOUBLE-MUSCLED BELGIAN BLUE BULLS PERFORMANCE-TESTED IN BELGIUM

For 1,442 Belgian Blue bulls performance-tested at the Centre de Selec tion de la Race Blanc-Bleue Belge, nine traits were observed: height a t withers at 7 mo, height at withers at 13 mo, weight at 7 mo, weight at 13 mo, average feed consumption of concentrates, average daily gain , average feed consumption of concentrates per average daily gain, ave rage feed consumption of concentrates per mean metabolic weight, and p rice per kilogram of live weight. This price is based on muscle confor mation and is therefore used as muscle conformation score. Restricted maximum Likelihood with a derivative-free algorithm was used to estima te (co)variance components because there were different models and mis sing values per trait. Estimates of heritabilities were above .50 exce pt for average feed consumption per average daily gain (.16) and avera ge feed consumption per mean metabolic weight (.33). Estimates of gene tic and phenotypic correlations between height at withers and weight t raits were positive and moderate to high. Average daily gain showed a negative genetic correlation with weight at 7 mo (- .68) but had posit ive correlations with height at withers at 13 mo and weight at 13 mo ( .22 and .43). Muscle conformation expressed as price per kilogram of l ive weight was related to low average feed consumption per average dai ly gain. Average feed consumption showed high correlations with weight at 7 mo and weight at 13 mo. Average feed consumption per average dai ly gain had a high negative genetic correlation with average daily gai n (- .89).