Cruz et al., 2009. Rev. Bras. Zootec., 38 (1): 139-148
Desempenho de bezerros da raca Nelore e cruzados desmamados recebendo concentrado em pastagem adubada de Cynodon dactylon cv. Coastcross
223 purebred Nelore and crossbreds Canchim * Nelore, Angus * Nelore and Simmental * Nelore calves received either mineral mixture or 3 kg/animal/day of concentrate containing 18.8% crude protein and 81.5% total digestible nutrients, on a dry basis, while in a rotational grazing of Cynodon dactylon cv. Coastcross fertilized pastures. Available forage (kg dry matter/ha) was different for paddocks of cattle receiving mineral mixture (2961 kg) from those receiving concentrate (3.383 kg). However, forage dry matter allowance was higher (9.9 kg/animal/day or 3.9% BW) for cattle receiving mineral mixture than for cattle receiving concentrate in the diet (9.0 kg/animal/day or 3.3% BW). Available forage had, on a dry basis, 13.6% protein, 79.8% neutral detergent fibre, 62.3% in vitro dry matter digestibility, 3.9 g/kg calcium, 2.0 g/kg magnesium, 2.5 g/kg phosphorus, 22.7 g/kg potassium, 2.8 g/kg sulfur, 9.9 mg/kg copper, 22.5 mg/kg zinc, 98 mg/kg manganese and 188 mg/kg iron. Statistical interactions of genetic group * supplementation and year * supplementation were observed for average daily gain and for stocking rates, while a grazing cycle * supplementation interaction was observed for stocking rates. The average daily gain of Nelore, Canchim * Nelore, Angus * Nelore and Simmental * Nelore, receiving mineral mixture in the diet, were 0.48, 0.63, 0.68 and 0.50 kg, respectively, while those animals receiving concentrate in the diet were 0.87, 0.95, 0.99 and 0.95 kg, respectively, in the same order of genetic groups. Average stocking rates of pastures grazed by all genetic groups receiving mineral mixture in the diet was 6.1 animal units/ha, while the pastures grazed by Nelore, Canchim * Nelore, Angus * Nelore and Simmental * Nelore showed values of 7.5, 7.6, 8.8 and 9.0 animal units/ha, respectively, for animals receiving concentrate in the diet. The genetic group affects performance of cattle grazing coastcross and shows interaction with supplementation of diet with concentrate.