EFFECT OF THE CUTTING AGE OF Brachiaria decumbens ON RUMEN FUNCTIONS AND in vitro GAS PRODUCTION

Abstract

<p>The aim was to evaluate the effect of cut age on ruminal function and <em>in vitro</em> gas production of <em>Brachiaria decumbens</em> grass. Eighteen parcels established with <em>B. decumbens</em> were used. For each treatment, T1: 45, T2: 60 and T3: 75 (cut days), the chemical composition, rumen degradation, digestibility, pH, ammonia, volatile fatty acids (VFA) and gas production were analyzed. It was observed higher (P &lt;0.05) effective degradation (58%; 0.02 k, 45%; 0.05 k and 38%; 0.08 k) and apparent digestibility (57%) at 45 days of cut. The ruminal pH was maintained between 6.99 to 7.51 from 6 h to 24 h post incubation between the different cut ages (P &lt;0.05). With respect to NH₃-N it was higher at 45 and 60 days (27.3 and 25.6 mg/L respectively). The VFA did not show differences between the treatments evaluated (P&gt; 0.05). The lowest (P = 0.0001) gas production was observed in the <em>B. decumbens</em> cut at 45 days (T1). It can be concluded that the best age for grazing of <em>B. decumbens</em> can be between 45 and 60 days of regrowth.</p>