摘要
O objetivo do trabalho foi avaliar os parametros da cin谷tica de degrada o ruminal da Brachiaria brizantha cv. Marandu, cortadas aos 28, 35 e 54 dias, pela t谷cnica in vitro de produ o de gases. Foram realizadas determina es dos teores de mat谷ria seca (MS), mat谷ria organica (MO), prote赤na bruta (PB), extrato et谷reo (EE), fibra em detergente neutro corrigida para cinzas e prote赤na (FDNCP), fibra em detergente 芍cido (FDA), nitrog那nio insol迆vel em detergente neutro (NIDN), nitrog那nio insol迆vel em detergente 芍cido (NIDA), lignina (LIG), Carboidratos totais (CT), carboidratos n o fibrosos (CNF), fra o B2 e fra o C, respectivamente. Os dados da produ o de gases foram ajustados ao modelo log赤stico bicompartimental. O delineamento utilizado foi inteiramente casualizado. Os dados foram submetidos 角 an芍lise de variancia e regress o, ao n赤vel de 5% de probabilidade.Houve efeito (p %26lt; 0,05) para as vari芍veis MS, FDNCP, FDA, NIDN, NIDA, CT, B2, com aumento linear 角 medida que avan ou a idade de corte. Para a produ o de gases a fra o A foi semelhante entre as idades de 28 e 35 dias, com 95,75 e 116,8 mL 1g-1 de MS, respectivamente. A idade recomendada para obten o do melhor valor nutricional doBrachiaria brizantha cv. Marandu foi aos 28 dias. The objective of the work was to evaluate ruminal fermentation kinetics parameters of Brachiaria brizantha, harvested at 28, 35 and 54 days, using the semiautomatic in vitro gas production technique. Analyses were carried out for dry matter (DM), organic matter (OM), crude protein (CP), ether extract (EE), neutral detergent fiber corrected for ash and protein (NDFAP), acid detergent fiber (ADF), neutral detergent insoluble nitrogen (NDIN), acid detergent insoluble nitrogen (ADIN), lignin (LIG), total carbohydrates (TC), non-fiber carbohydrates (NFC), fraction B2 and the fraction C, respectively. Thedata of gas production were adjusted to the bicompartmental logistic model. The design used was completely randomized. The data were submitted to analysis of variance and regression, at the level of 5% probability. There was a significant effect (p %26lt;0.05), for the variables DM, NDFAP, ADF, NDIN, ADIN, TC, B2, with linear increase as harvest age advanced. For gas production, fraction A was similar between the ages of 28 and 35 days, with 95.75 and 116.8 mL g-1 of DM, respectively. The recommended age to obtain the best nutritional value of Brachiaria brizantha was 28 days.