Qualidade do pré-secado de Brachiaria brizantha em relação ao teor de matéria seca no armazenamento.

Abstract

Quality of Brachiaria brizantha pre-dried in relation to dry matter content in storage The dry matter content at the time of grass cutting influences the quality of the pre-dried produced. The objective of this study was to evaluate the pre-dried quality of Brachiaria brizantha grass-Marandu in relation to different moisture contents in storage, evaluating chemical composition, microbial populations, gas production, pH, NH3, volatile fatty acids, soluble carbohydrates, buffer capacity and aerobic stability. The design used was completely randomized with five replicates per treatment, which consisted of four dry matter contents (in natura material having 80%, with 40%, 50% and 60% DM). The chemical composition of the pre-dried presented difference only for the dry matter content and soluble carbohydrates between the different DM contents of the preserved material. The treatment 60% DM presented higher levels of DM and CHO's with mean values of 563.8 g kg−1 and 42.0 g kg−1, respectively. The concentration of O2 stabilized from the 7th day onto <2% values regardless of the DM content of the stored material, while in the treatment with 60% of DM a higher CO2 concentration was observed. The highest pre-dried temperatures were observed in the first 15 days of storage for all treatments. There was no difference between treatments for lactic acid bacteria (BAL), with an average of 6.98 log cfu g-1. Regarding the concentrations of fatty acids there was an effect (P<0.05) only for acetic acid, being the lowest concentration observed for the pre-dried in natura, with the value of 8.58 g kg-1. DM. Regarding ammoniacal nitrogen, there was a higher amount in the treatment with 40% DM with an average value of 1.62 %. Pre-dried with 50 and 60% DM presented values lower than 1.0%. The pre-dried with DM content between 50% and 60% present better characterization of quality of preserved forage.