Genetic parameters for calving ease in Italian Simmental cattle

Estimated breeding values for Calving Ease for Italian Simmental bulls are not available, so it is not possible to develop appropriate mating schemes. The aim of this study was to estimate genetic parameters for calving ease in Italian Simmental cows, using a bivariate linear animal model. Calving ease scores for first and later parities cows were considered as different but correlated traits. The model accounted for contemporary groups, sex of calf, season of calving within region, and age at calving within parity effects; both direct and maternal genetic effects were considered. Heritabilities of direct (4.9-3.2%) and maternal (3.4%-1.2%) effects were comparable to values reported for other Simmental populations. The genetic correlation between first and later parities calving ease was 0.974 and 0.779 for direct and maternal genetic effects, respectively. The genetic correlation between direct and maternal effects was -0.331 and -0.412 for first and later parities, respectively. Genetic evaluation for calving difficulty is feasible, but is necessary to improve the quality of the data.