Whole-genome scan for quantitative trait loci associated with birth weight, gestation length and passive immune transfer in a Holstein x Jersey crossbred population

We herein report results from a daughter design genome-scan study aiming to identify quantitative trait loci (QTL) associated with birth weight, direct gestation length and passive immune transfer in a backcross (Holstein x Jersey) x Holstein population. Two-hundred and seventy-six calves, offspring of seven crossbred sires, were genotyped for 161 microsatellite markers distributed along the 29 bovine autosomes. The genome scan was performed through interval mapping using an animal model in order to identify QTL accounting for phenotypic differences between individual animals. Based on significant chi-squared values, we identified putative QTL on BTA7 and BTA14 for gestation length, on BTA2, BTA6 and BTA14 for birth weight and on BTA20 for passive immune transfer. In total, these QTL accounted for 12%, 18% and 1% of the phenotypic variance in gestation length, birth weight and passive immune transfer respectively. We also report results from a supplementary and independent influential grand-daughter Holstein family. In this family, findings on BTA7 and BTA14 for direct gestation length were in agreement with results in the crossbred population. Two other regions on BTA6 and BTA21 putatively underlying QTL for direct gestation length variability were discovered with this analysis.