Environmental effects on pre-weaning traits in Santa Gertrudis cattle

Abstract

We aimed to evaluate environmental effects on pre-weaning traits of Santa Gertrudis cattle. We used 213 standardized records for adjusted 205-day weight at weaning (W205), average daily gain from birth to weaning (AGD), and number of days to gain 160 kg from birth to weaning (D160), obtained from the Santa Gertrudis Breeders' Association for animals born between 1990 and 1997. The files were edited with information regarding cow age at calving (CAC) and contemporary group (CG), for which the effects of year and season of birth, animal category, herd, and sex were considered. It was observed that cow age at calving, which had linear and quadratic effects, and effect of contemporary group were significant (P < 0.0001) for the evaluated traits. Estimated averages were 198.05 ± 40.64 kg, 0.790 ± 0.198 kg day-1, and 288.05 ± 67.18 days for W205, ADG, and D160, respectively. Males were 4.67 kg heavier (197.17 kg) than females, on average. Regarding the animal category effect, the classified females were 2.3% heavier than the unclassified, on average. On average, animals born in the dry season were 1.6% lighter than those born in the rainy season (197.18 kg). Thus, environmental effects are important and should be considered in any analysis model.