Fermentation kinetics and degradation rates of three tropical forage species (Tanzania grass, Marandu grass and Tifton 85 grass) were evaluated by the in vitro gas production technique. The forages were harvested at 28, 35 and 42 days of regrowth during two periods, January-March and April-June. In the January-March period, Marandu grass presented the greatest values of fraction A, potential degradability (PD) and effective degradability for a passage rate of 2 %/hour (ED2). In the April-June period, Marandu and Tanzania grasses presented similar results for the variables tested above. In both periods, Tifton 85 had the lowest values of fraction A, PD and ED2, and the greatest value of fraction C. In the April-June period, there was an age effect in relation to gas production potential and 96 hours of incubation with the lowest value was found for 28 days of regrowth. The lowest fermentation rates were observed in general for Tifton 85 grass in the April-June period, regardless of the regrowth age.
effective degradability; fermentation; marandu grass; potential degradability; tanzania grass; tifton 85 bermudagrass
