This work was carried out to study the effect of protein and mineral salt supplements in comparison to mineral salt on performance of growing and finishing steers, and to evaluate the availability, chemical composition and in vitro digestibility of forage during the winter. Seventy four steers were used, 37 with 266 kg of initial body weight and 37 with 377 kg of initial body weight. At the onset of the fall grass production period in May both animal groups (growing and finishing) were divided into two treatments: mineral supplement (MIS) or protein and mineral supplement (PMS). Four pastures of violet star grass forage (Cynodon plectostachyus Pilger) were used, in continuous grazing. The quality and availability evaluation of forage were estimated every 28 days. The average intake of mineral salt and protein mineral salt were 42 and 184 g per animal a day for growing animals and 57 and 281 g per animal a day for finishing animals. There was no difference in average daily gain between treatments, either for growing animals (0.17 kg a day and 0.16 kg a day) and finishing animals (0.01 kg a day and 0.02 kg a day). However, the average daily gain for growing animals was superior (0.17 kg a day) when compared with finishing animals (0.01 kg a day). The quality and availability of the pasture were similar to the different treatments, with average levels of 3643 kg of dry matter/ha, 2041 kg of green dry matter/ha, and 285 kg of leaves/ha. The leaf proportion was small (7%) for all treatments in function of the high dead material (44%) proportion. The pasture had in average 4.5% CP, 1.8% DCP, 79.9% NDF, 51.5% ADF, and 44.0% IVDMD.
beef steers; protein supplementation; urea; weight gain
