Digestibilidade e Parâmetros Ruminais de Bovinos Consumindo Brachiaria Brizantha Cv. Marandu

Abstract

This experiment aimed to evaluate nutrient intake, total and partial digestibility of dry matter (DM), organic matter (OM), crude protein (CP), neutral (NDF) and acid (ADF) detergent fiber and ruminal parameters, ammonia concentration and volatile fatty acids, in beef cattle fed palisade grass (Brachiaria brizantha cv. marandu) at two regrowth ages, 30 and 60 days, at two times of year (January and February). The intake of DM, OM and CP was influenced by forage age of regrowth with high values for 30 days; this was influenced by time of year, being observed in February the higher intake by animals. DM digestibility average was 60.7 and 59.4% for 30 and 60 days of forage regrowth, respectively, however, was observed effect of interaction between regrowth and time of year, the same comportment was observed for OM, averages were 63.9 and 63% for respective ages of regrowth. CP digestibility was higher for 30 days, 70.8%, than for 60 days of regrowth, 57%. The NDF and ADF digestibilities were influenced by the interaction between regrowth and time of year; their average for 60 days of regrowth in January were respectively 54.8 and 48.5%, being the lower values and, in February, the higher values: 64.9 and 60.4%. The ruminal average digestibility was 79.5, 86.2, 99.4 and 96.7% of the total degradable for DM, OM, NDF and ADF, respectively. Effects of regrowth and time of year there were not recorded. Two hours after the morning meal was observed the ammonia ruminal concentration peak. The acetate:propionate: butirate ruminal ratio observed was 74:18:8(%).