Genetic parameters of serum vitamin A and total cholesterol concentrations and the genetic relationships with carcass traits in an F1 cross between Japanese Black sires and Holstein dams.

Blood sample and carcass trait data were collected from 841 and 3,219 fattening animals of an F(1) cross between Japanese Black sires and Holstein dams, respectively. Data on serum vitamin A and total cholesterol concentrations containing 582 to 739 records at 4 stages of beef-fattening production were used to estimate variance components and heritabilities for the 2 traits, based on fattening periods: less than 13 mo of age (stage 1), 14 to 18 mo of age (stage 2), 19 to 21 mo of age (stage 3), and greater than 22 mo of age (stage 4). Furthermore, the genetic correlations of serum vitamin A and total cholesterol concentrations with beef marbling standards, carcass weight, ribeye area, rib thickness, and subcutaneous fat thickness were estimated. The heritability estimates of serum vitamin A concentration were consistently and drastically decreased from 0.37 ± 0.15 to 0.07 ± 0.07 from stages 1 to 4 because of considerable decreases in sire variances, whereas the residual variances remained large and stable throughout all 4 stages. Serum total cholesterol concentration was moderately heritable (approximately 0.35 to 0.64) throughout all 4 stages. The genetic correlations among serum vitamin A concentrations and beef marbling standards were high and negative (-0.94) in stage 4. The genetic correlations between serum vitamin A concentration and carcass weight in stages 3 and 4 were moderate and positive (approximately 0.26 to 0.36). Moderate to high positive genetic correlations between serum vitamin A concentration and subcutaneous fat thickness were obtained throughout the stages (approximately 0.40 to 0.75). Genetic correlations of serum total cholesterol concentration with carcass weight and rib thickness were moderate and positive (approximately 0.29 to 0.46) in stages 2, 3, and 4. These results indicate serum vitamin A and total cholesterol concentrations could be effective physiological indicators for improving carcass traits.