Effects of ignoring and adjusting records for feed intake on estimates of genetic parameters for yield and composition traits in Holsteins

Estimation of genetic parameters from dairy records is customarily based on data from cows receiving unequal amounts of feed. Highyielding cows are given relatively more concentrates while the lowyielders are given relatively more roughage. The effects of the level of feed of the cow on estimation of genetic parameters are, generally, ignored; this can cause overestimation of genetic and phenotypic correlations between yield traits. Accurate estimates of the genetic and phenotypic (co)variance components are essential in the prediction of breeding values and in formulation of optimum livestock breeding programs. Objective The main objective of this study was to investigate the consequences of ignoring and adjusting dairy records for feed intake, using field data, on estimates of genetic parameters for milk, fat and protein yields and composition traits in early and late periods of first lactation of Holsteins.[...