Single Nucleotide Polymorphisms in the Fatty Acid Binding Protein 4, Fatty Acid Synthase and Stearoyl-CoA Desaturase Genes Influence Carcass Characteristics of Tropical Crossbred Beef Steers

This study explored the identification of single nucleotide polymorphisms (SNP) in fatty acid binding protein 4 ( FABP4 ), stearoyl-CoA desaturase ( SCD ), and fatty acid synthase ( FASN ) genes that may influence the carcass traits of tropical crossbred beef cattle. The hypothesis tested was that SNP in the FABP4 , SCD, and FASN genes are associated with chiller-assessed carcass traits of tropically adapted northern Australian crossbred beef cattle. Fifty Bos indicus and Bos taurus crossbred steers were backgrounded on either buffel grass only, or buffel grass and desmanthus mixed pastures for 147 days and finished in a commercial feedlot for 110 days. Steers were slaughtered within 48 h of leaving the feedlot within a lairage period not exceeding 12 h and carcasses graded 12 h after slaughter. Next-generation sequencing of the FASN , FABP4, and SCD genes identified multiple SNP loci that were correlated and significantly associated with carcass traits. The FABP4 g.44677205A>G locus was significantly associated with hump height and correlated with loin eye muscle area (EMA; p < 0.05). Polymorphism in the SCD gene g.21275851C>A locus was associated with subcutaneous fat depth and marbling score ( p < 0.05). The CC genotype had a higher subcutaneous fat depth and marbling score ( p < 0.05) than the AA genotype. Significant correlations were observed between carcass marbling score and subcutaneous fat depth within the FASN SNP locus ( p < 0.05). Therefore, the hypothesis that SNP in the FABP4 , SCD, and FASN genes are associated with chiller-assessed carcass traits of tropically adapted northern Australian crossbred beef cattle was accepted. These findings suggest that SNP in the FABP4 , SCD, and FASN genes may be used in carcass grading and meat quality improvement through marker-assisted selection of northern Australian crossbred beef cattle.