Abstract #W73

# W73
An SNP association study evaluating Brahman and Brahman-influenced steers for growth and carcass traits.
Amanda Royer1, Chris Shivers3, David Riley4, Mauricio Elzo5, Matthew Garcia*1,2, 1Louisiana State University School of Animal Sciences, Baton Rouge, LA, 2LSU AgCenter, Baton Rouge, LA, 3American Brahman Breeders Association, Houston, TX, 4Department of Animal Science, Texas A&M University, College Station TX, 5Department of Animal Science, University of Florida, Gainesville, FL.

Brahman cattle are important in tropical regions due to the breed’s ability to tolerate excessive heat and parasite presence. However Brahman cattle exhibit lower yielding, lower quality carcasses as compared with Bos taurus breeds. The objective of the current study was to evaluate potential SNP associations on 4 candidate genes for growth and carcass traits in a population of Brahman and Brahman-influenced steers. A total of 42 Brahman and Brahman-influenced steers born between 2009 and 2014, at Louisiana State University Central Research Station in Baton Rouge, Louisiana, were utilized. Steers were evaluated through the American Brahman Breeders Association (ABBA) carcass evaluation project in Gonzales, Texas, for growth, feedlot performance, and carcass quality and composition traits. Growth traits measured at the Central Research Station beef unit before shipment to the feedlot include birth weight, weaning weight, and hip height. Traits measured in Gonzales, Texas, included feedyard entrance weight, harvest weight, and average daily gain. Carcass traits measured include hot carcass weight, ribeye area, marbling score, yield grade, quality grade, dressing percent, and Warner-Bratzler shear force score. A mixed model design with growth, carcass traits and individual SNP genotype fit as dependent variables and breed type, year, dam fit as independent variables was utilized to evaluate potential SNP associations. Sire was fit as a random variable in the model. Four known candidate genes were chosen for SNP analysis based on previous association with growth and carcass traits. Candidate genes include calpastatin (CAST), calpain (CAPN), thyroglobulin (TG), and adiponectin (ADIPOQ). A total of 20 SNP were chosen for each CAST and CAPN, and a total of 30 SNP were chosen for each TG and ADIPOQ. All SNP were selected equidistantly spaced across each candidate gene. Although multiple SNP in the current study were significantly (P < 0.05) associated with growth and carcass traits, they must first be validated in much larger and diverse populations before implementation into selection strategies.

Key Words: Bos indicus, carcass trait, growth