Performance of beef cattle of different genetic groups weaned at 3 or 7 months of age

The objective of this experiment was to evaluate the performance up to 24 months of age of males from two breeding systems, straightbred (Charolais - C and Nellore - N) and crossbred (1/2 CN, 1/2 NC), submitted to two ages of weaning: T3-weaning at three months of age; T7-weaning at 7 months of age. The calves were maintained from birth to the weaning time with the cows on native pasture and, after weaning, both animals from T3 and T7 were maintained during a period of 30 days in a feedlot. The animals from T3, from 4 to 7 months, were maintained on pearl millet pasture (Pennisetum americanum). The weights at 3, 7, 12, 18 and 24 months of age and the average daily gain (ADG) among the different ages were collected. There was no interaction between the breeding system and genetic group within breeding system and age at weaning for the studied variables. The average daily gain of the T3 calves was lower from 3 to 7 months and higher from 7 to 12 months, afterward no difference was observed in the ADG. The only difference for weight was at 7 months, when T7 calves showed higher weight. The weight at 24 months was 424 and 423 kg, respectively, for T3 and T7. The crossbred animals showed higher ADG from 7 to 18 months and were heavier at 18 and 24 months. The heterosis for ADG ranged from .6 to 29.9%, and for weight at different ages ranged from -.68 to 12.41%. When the nutrition conditions are adequate, the weaning at 3 months does not affect slaughter weight at 24 months of age.