Estimativas de efeitos aditivos e heteróticos para características de crescimento pré-desmama em bovinos charolês-Nelore

The objective of this study was to estimate direct and maternal additive and individual and maternal heterotic effects for birth weight (13W), weaning weight (WW) and average daily gain (ADG) from birth to weaning, for Charolais and Nellore cattle. Data on Nellore and several Charolais - Nellore crossbred groups were used. The least squares multiple regression procedure, to divide the genetic group effects into additive and heterotic effects, was used. The analyses of variance showed that the additive and heterotic effects were important sources of variation for all traits studied, except the heterotic maternal effect for BW. The direct and maternal additive effects of the Charolais breed, as a deviation from Nellore, were equal to 2.03 \241 .58 and 6.77 \241 .59 kg for BW, 9.99 \241 3.61 and -23.31 \241 3.70 kg for WW and .038 \241 .013 and -.089 \241 .014 kg/day for ADG, respectively. The individual and maternal heterotic effects were equal to 1.66\241.34 and 0.62\241.44 kg for BW, 14.77\241 2.14 and 44.16\241 2.77 kg for WW and.044\241.008 and. 143 \241.011 kg/day for ADG, respectively. These results show that: 1. The higher the proportion of genes of the Charolais breed in the calf, the greater its growth to weaning, 2. The higher the proportion of genes of the Charolais breed in the dam, the bigger the BW and the smaller the WW and the ADG of the calf, and 3. The higher the proportion of heterozygous loci in the calf and in the dam, the greater the growth of the calf to weaning.(RA)