Environmental effects on preweaning performance traits in Nellore beef cattle

Abstract

The objective of this study was to analyze a data set with 205 records from a Nellore breed cattle, evaluating the influence of environmental factors on weaning weight adjusted to 205 days of age (W205), preweaning average daily gain (ADG) and number of days to gain 160 kg (D160). The data came from a farm in São Paulo State and were collected from 2007 to 2010. The statistical analysis was accomplished using the least squares method, with a model that included the fixed effects of contemporary group, sire and cow age at calving, and error as random effect. The same model was used to analyze 124 records of weight adjusted to 90 days of age (W90). The effects of contemporary group and sire were significant. The cow age at calving was not significant for any performance trait analyzed, except for W90 (P < 0.05). The estimated means were 140.67 ± 20.08 kg, 0.539 ± 0.097 kg/day and 306.42 ± 55.84 days, for W205, ADG e D160, respectively. The weightless calves were born in February (115.65 kg) and the heaviest in July (156.18 kg). The males were 5.8% superior than females. The importance of non genetic effects indicates the need to consider them when estimating genetic parameters and breeding values for selection purpose.