Degradation characteristics of crude protein and crude fiber of legume forages in the rumen of goat

The nutritional value of a feedstuff depends not only on its chemical composition but also on the capacity of rumenal microbes to colonize and degrade it. This study compared the in sacco degradation kinetics of four legume forages (Moringa oleifera, Leucaena leucocephala, Indigofera and Gliricidia sepium) using three rumen fistulated goats in a 4×3 completely randomized design (CRD). Seventy-two nylon bags (10 × 5 cm, 40–50 μm pore size) containing 5 g of each forage (ground to 2 mm) were incubated for 4, 8, 12, 24, 48, or 72 hours (12 bags per time point). The study determined the soluble fraction (a), potentially degradable fraction (b), total degradable fraction (a+b), degradation rate constant of fraction b (c), lag time (Lt), degradation effectiveness (DE), and rumen undegradable protein (RUP). The results of CP degradation revealed no significant differences among forages in fractions a, b, or a + b, but fraction c, Lt, DE, and RUP differed significantly. The degradation rate (c, h⁻¹) of crude protein ranked as Moringa (0.17) > Leucaena (0.09) = Indigofera (0.09) > Gliricidia (0.03), while Lt was shortest for Moringa (3.60 h) and longest for Gliricidia (11.96 h). Moringa and Indigofera exhibited the highest DE and lowest RUP of all treatments. Similar trends were observed for crude fiber: Moringa showed the greatest DE (26.72% Lt) compared to Leucaena (18.76 h Lt). In conclusion, all four legumes were efficiently degraded in the goat rumen, through the rate and extent of degradation varied markedly among species, reflecting differences in their biochemical composition and structural carbohydrates.