%0 Journal Article
%T Genetic and environmental heterogeneity of residual variance of weight traits in Nellore beef cattle
%A Haroldo HR Neves
%A Roberto Carvalheiro
%A Sandra A Queiroz
%J Genetics Selection Evolution
%D 2012
%I BioMed Central
%R 10.1186/1297-9686-44-19
%X A two-step approach was applied to study the genetic heterogeneity of residual variance of weight gain from birth to weaning and long-yearling weight in a Nellore beef cattle population. First, an animal model was fitted to the data and second, the influence of additive and environmental effects on the residual variance of these traits was investigated with different models, in which the log squared estimated residuals for each phenotypic record were analyzed using the restricted maximum likelihood method. Monte Carlo simulation was performed to assess the reliability of variance component estimates from the second step and the accuracy of estimated breeding values for residual variation.The results suggest that both genetic and environmental factors have an effect on the residual variance of weight gain from birth to weaning and long-yearling in Nellore beef cattle and that uniformity of these traits could be improved by selecting for lower residual variance, when considering a large amount of information to predict genetic merit for this criterion. Simulations suggested that using the two-step approach would lead to biased estimates of variance components, such that more adequate methods are needed to study the genetic heterogeneity of residual variance in beef cattle.In most linear mixed models used in animal breeding, it is usually assumed that residual variance is constant across genotypes. However, recent studies have provided statistical support for the hypothesis that residual variance (¦Ò2e) is partly under genetic control, highlighting its importance in livestock e.g. [1-4]. Comprehensive reviews on this topic have been reported in [5] and [6].Mackay and Lyman [7] have found strong experimental evidence of genetic heterogeneity of residual variance in bristle number between isofemale lines of Drosophila. More recently, divergent selection experiments for birth weight [8] and litter size [9] in rabbits confirmed that residual variance is genetically controll
%U http://www.gsejournal.org/content/44/1/19