Association analyses of single nucleotide polymorphisms in bovine stearoyl-CoA desaturase and fatty acid synthase genes with fatty acid composition in commercial cross-bred beef steers.

Two previously reported non-synonymous coding single nucleotide polymorphisms (SNPs) of bovine stearoyl-CoA desaturase (delta-9-desaturase) (SCD) (c.878C>T) and fatty acid synthase (FASN) (g:17924A>G) were assessed for their associations with 72 individual and 12 groups of fatty acids in brisket adipose tissue of 223 Canadian commercial cross-bred beef steers. It was found that the 'CC' genotype of the SCD SNP was significantly associated with lower concentrations of saturated fatty acids (SFA) including 10:0, 14:0 and 20:0, higher concentrations of monounsaturated fatty acids including 9c-14:1, 12c-16:1 and 13c-18:1, higher concentrations of polyunsaturated fatty acids (PUFA) including 9c,15c-18:2, 10c,12c-18:2, 11c,13t-18:2 and 12c,14t-18:2, but lower concentrations of other PUFA of 9c,13t/8t,12c and 20:2n-6 (P < 0.05). The 'AA' genotype of the FASN SNP was significantly associated with higher concentrations of SFAs of 10:0, 12:0, 13:0, 14:0 and 15:0, lower concentrations of unsaturated fatty acids of 9c-18:1 and 20:3n-6, and higher concentrations of unsaturated fatty acids of 9c-14:1 and 12c-16:1 (P < 0.05). Significant epistatic effects between the SCD and FASN SNP genotypes were also found for several fatty acids including 10:0, 23:0, 6t/7t/8t-18:1, 12t-18:1, 13t/14t-18:1, 16t-18:1, total trans18:1 and 9c,13t/8t,12c-18:2 (P < 0.05). These results further suggest that SCD and FASN are strong candidate genes influencing fatty acid composition in beef cattle.