Performance European - Zebu crossed calves in Brasil

The objective this work was evaluate the influence of genetics and environmental effects in birth and weaning weight crossbreed calves, raised in pasture, with additional supplementation. Use 482 records of birth and weaning weights of calves sons of Nellore (NE), Hereford (HE), Aberdeen x Nellore (½ AB ½ NE) e Limousin x Nellore (½ LI ½ NE) dam, breeding Charolais (CH), Hereford (HE) e Red Angus (RE) bulls. The statistical analysis was done used three models. The first one had a fixed effect of sex of calf, type of breeding (Artificial insemination or natural breeding), month of calving (June at October), breed of bull and breed of dam. The second model was composted of breed calf (genetic group), sex, breed calf x sex interaction, breeding type and month of calving. The third model is similar of the second, but the breed of calf was dismembering by Nellore blood with variation 0, ½ and ¾. The three cross caves, ¼ Nellore show a height weaning weight for both sex. In the weaning weight males of genetic groups CHLINE and females RELINE showed the higher weight. The weight of calves ½ Nellore was light at birth. But, at weaning the “three cross” were higher followed to ½ bloods 15.84% and 2.92%, respectively, this probably in function of heterosis and best maternal ability of dam ½ Nellore. The three cross calves, ¼ Nellore showed high weight in weaning for both sex reveling with a good option to pretend do crossbreed program