Abstract
Data of 682 blood samples and carcass traits from 198 crossbred steers and heifers between Japanese Black sires and Holstein cows were used to identify the effects of genetic (sire) and environmental (season, age, sex, farm and the interactions) factors on serum vitamin A and total cholesterol concentrations and investigate the relationships between these concentrations and carcass traits. Least squares analysis of variance showed that season, age and season x age had significant effects on both serum vitamin A and cholesterol concentrations. Sire and farm effects were only significant in serum vitamin A and total cholesterol concentrations, respectively. There was no significant relationship of serum vitamin A concentration with carcass traits except rib-thickness at the age of 18 to 20 months in the correlation analysis and BCS number at the age of 12 to 17 month in the covariance analysis. The results from both correlation and covariance analysis showed that total cholesterol concentration had positive effects on BMS number, carcass weight, rib eye area and rib-thickness and a negative effect on BCS number in the later stage of fattening. This indicates that the total cholesterol concentration can be a good indicator for predicting these carcass traits before slaughter.
