Multi-trait animal model based estimation of direct and correlated responses in Frieswal cattle

Abstract

The study was undertaken to estimate the genetic parameters, direct and correlated responses for the test day and lactation milk yield in Frieswal cattle. Data on 9,955 daily milk yield records of 973 Frieswal cows calved during 2005 to 2014 at Ambala and Meerut dairy farms were utilized. The variance components, heritability estimates, genetic and phenotypic correlations for all the 11 traits were estimated simultaneously by fitting multi-trait animal model using the Wombat program of Meyer (2006) with contemporary groups as fixed effect, the additive genetic random effects, linear and quadratic regressions of covariate age at first calving and linear regression of covariate first lactation length. The expected genetic gain (DG), correlated response (CR) in cumulative 305-day yield and vice versa and the relative efficiency (RE %) of selection based on different test day yields were estimated. The results revealed lower additive genetic variance and heritability estimates for different test days and cumulative 305-day yield. The genetic correlations between the test days up to 225 and cumulative 305-days were higher which indicated the positive relationship between these traits. The higher correlated responses in cumulative 305- day yield estimated through the selection for TD135, TD165 and TD45, in that order indicated that early selection of sires using test day records would be efficient in genetic improvement for lactational milk yield in Frieswal breed of cattle.