ESTIMATION OF GENETIC-PARAMETERS OF PREWEANING PERFORMANCE IN THE FRENCH LIMOUSIN CATTLE BREED

Direct and maternal genetic and environmental parameters of preweaning growth and conformation at weaning were estimated in the French Limou sin beef cattle field recording program using the tilde-hat approach o f Van Raden and Jung (1988) with a sire, maternal grandsire (MGS) and dam within MGS model. The numerator relationship matrix among bulls wa s included in the estimation. The data available after editing contain ed 169 391 calves with performance records, from 43 683 dams, 7 265 si res, 5 664 maternal grandsires and 1605 herds, for the years 1972-1989 . The traits involved were: birth, 120-d and 210-d weights, average da ily gains from birth to 120-d, from 120-d to 210-d, from birth to 210- d, muscular development (MD) and skeletal development (SD) scores at w eaning. Estimates ranged from 0.22 to 0.32 for additive direct heritab ilities and from 0.06 to 0.16 for maternal heritabilities. Correlation s between direct and maternal genetic effects for these traits were ne gative, ranging from -0.23 to -0.49. Maternal permanent environmental effects were small for all traits, accounting for 5-9% of the phenotyp ic variances for preweaning growth performance, and 3% and 4% for MD a nd SD, respectively.