PSXV-5 - Incorporating Breed of Origin and Runs-of-homozygosity Information in a Genome-wide Association for Meat Traits in a Brangus Commercial Herd

Abstract: Heterosis is the tendency of crossbreed animals performing better than the average of the purebred parents. Heterosis retention is essential in crossbreeding and composite breeding systems. However, not every genomic region benefits from heterosis, with certain traits showing an improvement when certain genomic regions are kept fixed for a certain breed. The objectives of this study were to detect such regions in a commercial Brangus herd, using genotypes, and Breed of Origin (BO) genotypes to identify runs of homozygosity (ROH) and investigate their effects on meat traits. The Brangus herd was genotyped with the Bovine GGP F250 array, after quality control, 99,669 variants, and 1,046 cattle remained. These genotypes were converted into BO genotypes with LAMP-LD, which describes the origin of the markers either from Angus or Brahman ancestry. The new BO genotypes and original genotypes were then used to identify ROH using the –homozyg function PLINK. The ROH genotypes were fit into a single locus mixed model for hot carcass weight (HCW) and marbling (MARB) using the EMMAX procedures in Golden Helix. The same single locus mixed model was used on both genotypes and Breed of Origin genotypes using the EMMAX procedures in Golden Helix. Using BO alleles, and ROH alongside traditional genotypes can help identify regions with significant effects on carcass traits. Providing important information for crossbreeding/composite breed systems about regions which should remain fixed for breeds.