Prado et al., 2004. Rev. Bras. Zootec., 33 (5): 1332-1339

The degradation kinetics, effective degradability (ED) of dry matter (DM), neutral detergent fibre (NDF) and crude protein (CP) with or without correction for microbial protein were evaluated in black oat ( Avena nuda), Mombaca ( Panicum maximum), star grass ( Cynodon plectostachyus) and millet ( Pennisetum glaucum) taken from pastures under continuous grazing. The forage was collected from different points of the pasture every 14 days for black oat and every 28 days for the other grasses. The feeds were incubated in the rumen of 3 bulls (350 kg body weight) using nylon bags at different times (0, 6, 12, 24, 48, 72 and 96 h). For correction of microbial protein contamination in the incubation residue, the neutral detergent insoluble protein analyses were performed. For DM, black oat and millet had higher soluble fractions (a=32 and 24%) and higher ED at 5%/h (53 and 48%, respectively). Winter star grass presented the lowest soluble fraction (14%) and the lowest DM ED at 5%/h (23%). For corrected CP, black oat and millet had higher ED (80 and 75%, respectively) than the other grasses (average ED of 67%). The degradation rate and ED of CP were underestimated when the correction for microbial contamination was not done. For NDF, black oat presented higher ED at 5%/h (40%) followed by millet (35%), star grass-summer (23%), star grass-winter (19%) and Mombaca (16%). Black oat and millet showed higher soluble fractions, higher degradation and higher ED of DM, CP and NDF when compared to star grass and Mombaca grass.