GENETIC PARAMETERS FOR GESTATION LENGTH AND PRE- AND POSTWEANING GROWTH TRAITS IN NELLORE CATTLE

Abstract

The objective of this study was to estimate heritabilities and genetic and phenotypic correlations for gestation length as calf trait (GLcalf) and preweaning [birth weight (BW) and weights at 120 (W120) and 210 (W210) days] and postweaning performance traits [weights at 365 (W365) and 450 (W450) days] in Nellore cattle participating in the Nellore Brazil Program coordinated by the National Association of Breeders and Researchers (Associacao Nacional de Criadores e Pesquisadores - ANCP). The parameters were estimated by the restricted maximum likelihood method under an animal model using the WOMBAT software. The genetic correlation between GLcalf and BW was 0.15, indicating a favorable association between the two traits which, however, was of small magnitude. GLcalf showed low positive genetic correlations (0.06 to 0.10) with the other weights, indicating that selection to reduce gestation length would not result in significant losses in weights at older ages. Furthermore, it is possible to infer that selection for higher W365 will not expressively increase gestation length.