The experiment was conducted to evaluate the ruminal pH and ammonia concentration (N-NH3) in rumen liquor collected at 3, 6 and 12 hours after feeding using four ruminal fistulated European x Zebu steers. The forage leaves: stems ratio and neutral detergent fiber (NDF) and acid detergent fiber in situ ruminal degradability of the leaflets from three tropical legumes (leucaena, Leucaena leucocephala; pigeon pea, Cajanus cajan; and glycine, Neonotonia wightii) and leaves from two others tropical forages (ramie, Boehmeria nivea and cassava, Manihot esculenta) were also studied. Samples of 3 g (pigeon pea, glycine and ramie) or 5 g (leucaena and cassava) of the material were incubated in the rumen of the animals for periods of 3, 6, 12, 18, 24 and 48 hours. A split-plot design was used, in which plots were the forages and split plots were the six periods of ruminal incubation of the material, and the four animals were considered blocks. Ruminal pH and N-NH3 values probably allowed an adequate microbial fermentation. Forage leaves:stems ratio was variable among them and comparing to the literature. The forages NDF effective degradabilities (ED) were around 50%, being lower for pigeon pea leaflets (19.25%), which also demonstrated the lowest degradation rate (2.5%/h) and potential degradability (57.76%). ED values for NDF were negatively correlated to forages acid detergent insoluble nitrogen contents (r = -0.986). Pigeon pea was the worst forage concerning to the use of structural components.
fiber ruminal disappearance; tropical forages; steers; rumen
