Parâmetros genéticos de longevidade e produtividade de fêmeas da raça Nelore

Abstract

In order to estimate the (co)variance components, heritabilities and Genetic correlations of longevity and herd life in females, information of 56413 Births of females from a Nellore cattle herd, from 1950 to 2000, under different Condition of rearing and management, were used. It was studied the weaning Weight (W205), yearling weight (W365), weight in 550days (W550), weaning Weight of calf (W205C), yearling weight of calf (W365C), weight in 550 days of calf (W550C), age at first calving (AFC),calving interval (Cl),herd life (RL), longevity (LONG),reproductive effíciency (RE), index production(IP), index of metabolic production (IMP), sum of index production (SIP), sum of index metabolic production (SIMP). The analysis were performed using the MTDFREML software, estimating the (co)variance components by restricted maximum likelihood, assuming animal model. Direct genetic, maternal and permanent environmental effects were analyzed. Breeder farm, food regimen, rearer condition, birth calf year, birth calf season and calf sex, were analyzed too. Estimates of heritability showed similar results among the different analyses, beinghigher (0,24to0,75) for W205, W365, W550, W205C, W365C, W550C,IP, IMP, AFC, RL, LONG and lower (0 to 0,10) for RE, Cl, SIP and SIMP. In general, the estimates of genetic and phenotypic correlations among LONG and growth traits were negative, suggesting genetic antagonism between LONG and early maturity, between the LONG and reproductive and productive traits were positive, suggesting the significant action of reproductive and productive traits in the LONG. Some correlations between maternal genetic effect and the growth traits were negative.