Información climática asociada a estaciones productivas para el ajuste de modelos estadísticos de sistemas bovinos bajo condiciones extensivas

A study was designed to develop a birth season (BS) classification methodology and assess its impact on live weight traits when compared to a traditional BS classification method. Using meteorological information, and aridity index was computed. The proposed and traditional BS were compared by including them into contemporary groups (CG= herd, sex, year and BS) to adjust genetic evaluation models of studied traits. The variance components and breeding values with accuracies were estimated and compared. The proposed BS explained more phenotypic variation than traditional (≥9.8%). Genetic parameters showed important changes, more evident for weaning weight. According to the likelihood ratio test the compared models were statistically different (P<0.01). An improvement in CG structure was observed. Genetic correlations of breeding values showed important differences suggesting hierarchy changes. This method of BS classification might improve the statistical model fitting when meteorological information could be available.