The impact of genetic markers for tenderness on steer carcass and feedlot exit and heifer puberty traits in Brahman cattle

Abstract

Four genetic markers (T1, T2, T3 and T4) have been shown to have a significant effect on tenderness (measured as shear force) in Brahman cattle. This study examined the relationship between tenderness markers and steer (N = 940) feedlot exit and carcass, and heifer (N = 973) puberty traits. For most traits assessed, tenderness markers had no significant effects. Differences in T1 genotype, however, significantly (P < 0.05) affected P8 fat depth measured in steers at the end of finishing and/or on the carcass, as did T3 and T4. Regression coefficients for these relationships were consistently negative, showing that steers with more copies of the favourable alleles were leaner. When protocols were applied to combat false discovery in multiple testing analyses, the relationship between T3 genotype and feedlot exit P8 fat depth remained significant. T1 also influenced age at puberty in Brahman heifers, with the trait significantly reduced (regression coefficient = -14.54) for animals which had more copies of the favourable allele. The exploitation of tenderness markers in Brahman cattle will need to be undertaken with an awareness of the impact of selection for these markers on other production and puberty traits.