The objective of the experiment was to evaluate the performance of Charolais (CH) and ½Nellore (NE) ½CH (produced by CH cows), NE and ½CH ½NE (produced by NE cows) calves, mantained with the cows until weaning, on native pasture (NP) or winter (oat + italian rye grass) and summer (alexander grass) cultivated pasture (CP). Sixty straigthbred or crossbreds calves were used, and weighted at birth; 14; 42; 70; 98; 126; 154; 182 days; and at weaning. The cows milk yield was evaluated at the same date of the calves weighing, with exception at birth. Calves mantained on CP showed higher average daily weight gain (ADG) (733 vs 440 g) and were heavier at weaning (191,8 vs 128,6 kg) than calves mantained on NP. Quadratic effect was observed for calves ADG (y=489.89 + 3.96DAY - 0.0198DAY²), being the ADG maximum point (571 g) at 85 days of age for those mantained on NP and at 107 days (848 g) for those mantained on CP. Average daily milk yield explained 45% of calves weaning weight and 38% of the ADG. The correlations between the milk yield and calves ADG and weight were significant even in the advanced stages of lactation. The correlation between the average daily milk yield during the whole lactation period and the ADG was higher in animals mantained on CP (.54) than on NP (.44) and for F1 animals (.73) in relation to straigthbreds (.47). The lowest correlation between milk yield and ADG was observed for straigthbred NE calves (.31), for the other groups the correlation were .60; .71; and .84, for CH; ½CH ½NE and ½NE ½CH, respectively. Fat, lactose, nonfat dry extract and total dry extract contents did not show significant correlation with the ADG. However, when the total production of these components were considered, the correlations with ADG were significant. F1 calves were heavier at birth and weaning than straigthbreds. The heterosis for birth weight, weaning weight and ADG was, respectively, 3.4; 11.8; and 10.2%.
Charolais; crossbred; weight gain; heterosis; cow age; Nellore
