Performance evaluation of different beef cattle genetic groups under feedlot

Data from 188 animals from ten genetic groups were used. For the statistical analysis, the animals were grouped into three subgroups according to age, sex and diet. Thus, the subgroups analyzed were: 1) intacted yearling males receiving the "a" ration: 39 Nellore (N), 12 Brangus (BR), 8 1/2 Simmental - 1/2 Nellore (SN), 8 1/2 Caracu - 1/2 Nellore (CCN), 21 1/2 Valdostana - 1/2 Nellore (VAN); 2) intacted weaned males receiving the "b" diet: 12 N, 12 1/2 Canchim - 1/2 1/4 Angus - 1/4 Nellore (CAN), 16 1/2 Canchim 1/4 Simmental - 1/4 Nellore (CSN), 12 Braford - 1/2 Brangus (BRBD), 12 1/2 Braford - 1/4 Angus - 1/4 Nellore (BDAN), 7 Brahman 1/4 Angus - 1/4 Nellore (BHAN); 3) weaned females receiving the "b" diet under two formulations, one in which the concentrate represented 30% of total dry matter (DM) and the other in which the participation of the concentrate was 50% of total DM. For this subgroup the analysis included 29 females, 15 CAN and 14 CSN. Animals in subgroups I and 2, were fed a diet contained 50% of concentrate in the DM. Animals in subgroup I had similar performances. The average daily gain was 1.60 kg/day and average feed conversion was 6.41 kg of DM intake/kg of weight gain. The statistical analysis revealed that for average daily gain as well as for feed conversion, it were observed differences only among animals on subgroup 2. The greater average daily gain was recorded on CSN animals (1.69 kg/day) and the best feed conversion on CSN and BHAN animals (4.76 kg of DM intake/kg of weight gain and 4.67 kg of DM intake/ kg of weight gain). The analyses of subgroup 3 allowed the conclusion that in spite of not having any difference between genetic groups, formulation showed an important effect, mainly on feed conversion. The animals receiving the diet formulation in which the concentrate represented 30% of the total DM showed better feed conversion (5.58 kg of DM intake/ka of weight gain versus 6.66 kg of DM intake/ kg of weight gain).