Estimates of population parameters of some economic traits in Holstein Friesian cows by using statistical program.

Abstract

2 Abstract: Heritabilities, breeding values, phenoypic and genetic correlations for the various productive and reproductive traits were analyzed by using single-trait animal model analysis. Studied traits were age at first calving (AFC, months), age at calving (AC, months), services per conception (SC, services), calving interval (CI, days), days open (DO, days), dry period (DP, days), days in milk (DIM, days), total milk yield (TMY, kg), 305-days mature equivalent (305-ME, kg) and peak milk yield (PMY, kg). Estimates of heritabilites of AFC, AC, SC, CI, DO, DP, DIM, TMY, 305-ME and PMY were 0.24, 0.51, 0.21, 0.04, 0.10, 0.20, 0.10, 0.29, 0.31and 0.16, respectively. Generally, there were high positive (e.g. DP and CI) and negative (e.g. 305-ME and DP) genetic and phenotypic correlations between most studied traits. The highest range of breeding values for all traits was the range of TMY (9648.7 kg). The wide range of estimated breeding value (EBV) for any trait, suggests the presence of genetic variations between animals and hence the possibility of sire selection for daughter's productive and reproductive traits in the next generation, which would lead to more genetic improvement. In conclusion, this study will help the breeders to select the best dairy animals which will be used for production the future generations based on genetics of milk production and reproduction traits in early lactation.