Association analysis for feed efficiency traits in beef cattle using preserved haplotypes.

This study reports a genome wide scan for chromosome regions and their haplotypes that significantly associated with average daily gain (ADG), dry matter intake (DMI), and residual feed intake (RFI) in beef cattle. The study used data from 597 Angus, 450 Charolais, and 616 crossbred beef cattle, and the Illumina Bovine SNP50 beadchip. Extended haplotype homozygosity was used to identify chromosome regions that had been recently selected for in the three groups of animals. Such regions in the crossbreds were tested for association with ADG, DMI, and RFI. At false discovery rates of 5% and 10%, there were six and eight chromosome regions showing significant associations with the traits, respectively. At nominal significance levels (at least P < 0.05), 23 regions with a total number of 31 haplotypes were found significantly associated with at least one of the three traits. The proportion of phenotypic variance explained by these 23 regions varied depending on the trait; the highest proportion for ADG, DMI, and RFI was 13.50%, 9.92%, and 2.64%, respectively. Most of the haplotypes affected single traits, except for GAA (BTA4), GCG (BTA7), and TAGT (BTA12) that affected multiple traits. Thirty-six quantitative trait loci for 16 production traits, from the current literature, covered fully or in part the 23 chromosome regions. The findings from this study might be an important contribution to the current knowledge of the beef cattle genome and to the effective identification of causative genes associated with important traits in cattle.