66.035 recordsfrom Nellore, Hereford, Angus and Nellore x Angus and Nellore x Hereford crossbredcalves were analyzed to estimate the influence of cow age, age at weaning andthe julian birth date on average daily gain from birth to weaning. The statisticalanalysis indicated that these three covariates had significant effects on thistrait. Furthermore, the linear adjustment for age at weaning was not enoughto remove this effect on the average daily gain. These results show that theseenvironmental effects can be an important variation source for this trait inanimal improvement programs.
