Suplementação proteico-energética sobre o consumo voluntário e parâmetros ruminais em novilhos

The aim of this work was to evaluate the effects of protein and supplementation in ruminal parameters behaviour (pH and NH3-N), voluntary feed intake of hay, dry mater (DM) and neutral detergent fiber (NDF) degradability of hay. There were used five crossbred steers with mean live weight of 290kg. It were fed with Coast-cross (Cynodon dactilon) ad libitum hay and submitted to five different treatments, a control group received mineral mixture and hay ad libitum and four groups with various levels of protein and energy supplementation (0.25; 0.50; 1.00 and 1.50kg DM/100kg of live weight (LW/day). The ruminal pH varied from 6.62 to 6.33. Ruminal pH decreased with the increasing level of supplementation, but the only difference occurence between the control group and concentrate group 1.5kg DM/100kg LW/day. Ruminal NH3-N varied from 4.42mg to 75.11mg in the ruminal fluid. There were differences between supplementation levels, time of ruminal fluid collected and the relation between both aspects. Also 1.50% of LW showed the highest NH3-N concentration. No influence of protein and energy supplementation levels was observed for dry mater intake, crude protein and neutral detergent fiber intakes of hay. The DM and NDF potencial (maximum) degration (57.49% and 49.44% respectively) was achieved after 96 hours incubation. The supplementation had no influence on DM and NDF hay degradation, except in the 1.5kg DM/100kg LW/day.