Avaliaçao do peso à desmama e do ganho médio de peso de bezerros cruzados, no estado do Mato Grosso do Sul

The objective of this work was to compare the performanca of calves of different genetic groups until weaning time. Data from 3631 F1 calves progenies of Nellore cows mated with sires Aberdeen Angus, Brangus, Red Brangus, Canchim, Gelbvich, Nellore and Simmental, in Mato do Grosso do Sul state, were used (Group 1). Data of 1896 progenies of Nellore cows mated with siresof the above mentioned breeds and of the back crossbred Fl females mated with sires Gelbvieh and Nellore were also used (Group 2). The weaning weights (WW) were adjusted to the 230 days (WW230) and 240 days (WW240) for the groups I and 2, respectively, and the average daily gain until weaning (ADG) was determined for both groups. The mathematical model used in the Least Square Method, analysis included the fixed effects of contemporary groups (CG), calf genetic group (GG), and calf age at weaning and age of cow at calving. CG and GG influenced the studied traits in both groups. The calf age did not affect WW230 and ADG in the group 1, but in the group 2 it was significant for WW240 and ADG. The cow age at calving influenced the studied traits as much in the group I as in the group 2. The crossbred animals were superior to the pure Nellore in both groups. From group 2, a third set of data (Group 3) was obtained, containing the progenies of the backcrossbred Fl female, Nellore-Gelbvieh, mated with sires Gelbvieh and Nellore, containing 722 information of WW240 and ADG. In this file, the individual and maternal additive effects and individual heterotic effect were estimated. Only the individual heterotic effect was significant. (RA)