Desempeño de becerros cruzas europeo-cebú en Brasil

The objective of this work was to evaluate the influence of genetic and environmental factors on birth and weaning weights of crossbred, European x Zebu, calves raised on improved pastures and receiving supplemental feed. The data included 482 records of calves out of dams of the Nelore (NE), Hereford (HE), Aberdeen (AB) x Nellore (½ AB ½ NE) and Limousine (LI) x Nellore (½ LI ½ NE) breed groups, by sires of the Charolais (CH), HE and Red Angus (RE) breeds. Of three statistical models used, the first included the effects of sex of calf, type of insemination (natural or artificial), month of birth, breed of sire and breed of dam. The second model included breed of calf, sex of calf, interaction of breed calf x sex, type of insemination and month of birth. The third model was like the second, except that breed of calf was subdivided according to the proportion of Nelore inheritance, as 0, ¼, and ½. Based on least square means, birth of the males of ½ NE genetic composition was lower than that of the closely similar zero NE and ¼ NE groups. Birth weight of females was lowest for the zero NE group, intermediate for ½ NE and highest for ¼ NE calves. All individual genetic group means for both sexes fell within the limits of 31 to 38 kg. Weaning weights of both sexes showed the clear tendency ¼ NE > ½ NE > zero NE; the heaviest individual genetic groups were CHLINE (269.1 kg) among the males and RELINE (261.2 kg) among females, and the corresponding lightest groups were CHHE (207 kg) and REHE (226.1 kg). The advantageous performance of the three-breed crosses can be ascribed to heterosis and better maternal ability of ½ NE dams. Thus, the ¼ NE genetic groups of calves represent a good option for implementation in crossbreeding programs.