Suplementação alimentares protéico-energéticas de novilhos em pastejo

Increases in liveweight gain resulting from feeding concentrates on pasture can be accounted for by the increase in caloric intake. No direct response attributable to an increase in protein intake was found in these studies (Tables 2, 3, 4, 5). Grazing animals appear to substitute concentrate for pasture forage but at different rates depending on the quality of forage. During periods of low-quality forage (winter-dry season), each increase of 100 g of T.D.N. supplied in the concentrate resulted in a decrease in consumption of 76 g of T.D.N. from pasture forage. During periods of high-quality forage (summer-wet season), the substitution rate was 86 g of pasture T.D.N. for each 100 g of T.D.N. supplied in the concentrate. (Fig. 12) Nearly all increases in average gain per steer resulting from the feeding of concentrates occurred during the winter-dry season when forage quality was low. Nearly all the increase in gain per steer disappeared during the subsequent summer seasons, except where 2 kg of concentrate or more was fed per day. Since the feeding of concentrates on pasture reduces the intake of forage, a true evaluation of concentrates should include the measurement of their effect on the carrying capacity of the pasture. Rates of gain of steers on pasture were not affected by the addition of vitamin A or terramycin to the supplement (Fig. 10, Table 5). At a feeding level of 500 g of concentrate per steer per day, the amount of salt in the mixture was not effective in reducing the intake during the winter season, but the intake of supplement was reduced with increasing increments of salt during the summer season.