VARIANCE AND COVARIANCE ESTIMATES FOR WEANING WEIGHT OF SENEPOL CATTLE

Variance and covariance components were estimated for weaning weight from Senepol field data for use in the reduced animal model for a maternally influenced trait. The 4,634 weaning records were used to evaluate 113 sires and 1,406 dams on the island of St. Croix. Estimates of direct additive genetic variance (sigma-triple-overdot A2), maternal additive genetic variance sigma-triple-overdot M2), covariance between direct and maternal additive genetic effects (sigma-triple-overdot AM), permanent maternal environmental variance (sigma-triple-overdot PE2), and residual variance (sigma-triple-overdot-epsilon-2) were calculated by equating variances estimated from a sire-dam model and a sire-maternal grandsire model, with and without the inverse of the numerator relationship matrix (A-1), to their expectations. Estimates were sigma-triple-overdot A2, 139.05 and 138.14 kg2; sigma-triple-overdot M2, 307.04 and 288.90 kg2; sigma-triple-overdot AM, -117.57 and -103.76 kg2; sigma-triple-overdot PE2, -258.35 and -243.40 kg2; and sigma-triple-overdot-epsilon-2, 588.18 and 577.72 kg2 with and without A-1, respectively. Heritability estimates for direct additive (h triple-overdot A2 were .211 and .210 with and without A-1, respectively. Heritability estimates for maternal additive (h triple-overdot M2) were .47 and .44 with and without A-1, respectively. Correlations between direct and maternal (r triple-overdot AM) effects were -.57 and -.52 with and without A-1, respectively.