Influence of genetic and environment factors on the growing traits of animals from Nellore breed at Maranhio State

Growth records data of 688 animals from the Nellore breed reared in two herds in the El'Dourado farm were used to estimate the means, heritability coefficients and the genetic, phenotypic and environmental correlations for the birth weight, weaning weight and from birth to weaning daily gain (pre-weaning daily gain). The least-Square Method was used for the analysis of variance of data with unequal frequency in the subclasses. The average observed birth weight, weaning weight (at 205 days) and pre-weaning daily gain were equal to 32,77 +/- 3,37,190,81 +/- 37,37 and 0,771 +/- 0,128 kg/day, respectively. The hereditability for birth weight, weaning weight and pre-weaning estimated by the method of intra-class correlations among paternal half sibs in progeny from 84 sire, were 0,59 0,14, 0,42 +/- 0,13 and 0,35 +/- 0,17, respectively. The genetic, phenotypic and environmental correlation's between birth weight and weaning weight were 0,83 0,12, 0,33 and -0,31, respectively. The genetic, phenotypic and environmental correlations between birth weight and pre-weaning gain were equal to 0,77 +/- 0,16, 0,20 and -0,42 and between weaning weight and pre-weaning gain were equal to 0,99 +/- 0,03, 0,99 and 0,99, respectively.