Genetic parameters for daily live-weight gain, live fleshiness and bone thinness in station-tested Piemontese young bulls

Estimates of genetic parameters for beef production traits were obtained fo r Piemontese cattle. Data were from 988 young bulls station-tested from 198 9 till 1998. Bulls entered the station at 6 to 8 weeks of age and, after an adaptation period of 3 months, were rested for growth, live fleshiness and bone thinness. Length of test was 196 days. Growth traits considered were gain at farm, gain during the adaptation period, gain on test and total gai n at the station. Six different fleshiness traits and bone thinness were sc ored on live animals at the end of the test using a linear system. Live eva luations of fleshiness were adjusted for the weight at scoring in order to provide an assessment of conformation independent of body size. Genetic par ameters were estimated using animal models. Heritability of live-weight gai n ranged from 0.20 in the adaptation period to 0.60 for total gain at the s tation. Genetic correlations between gains at station in different periods were high (from 0.63 to 0.97). Residual correlation between gain during the adaptation period and gain during rest was negative, probably due to the o ccurrence of compensatory growth of the animals. Live fleshiness traits and bone thinness were of moderate to high heritabil ity (from 0.34 to 0.55) and highly correlated indicating that heavy muscled bulls also have thin bones. Accuracy of breeding values and therefore resp onse to selection were improved by multiple trait analysis of the live fles hiness traits and bone thinness. Overall weight gain at the station had a m oderate negative genetic correlation with all live fleshiness traits and bo ne thinness (from -0.11 to -0.39).