Variability in ash, neutral detergent fiber, total nitrogen and rumen degradability of six tropical legumes

The variability of three indicators of the chemical composition (ash, neutral detergent fiber and total nitrogen) and the effective rumen degradability (ERD) in situ of nutrients (DM, OM and Nt) were studied in six tropical legumes: jackbean (Canavalia ensiformis), dolicho (Lablab purpureus), mucuna (Stizolobium aterrimum), centro (Centrosema pubescens), siratro (Macroptilium atropurpureum) and glycine (Neonotonia wightii). In the chemical composition, the highest variations were found in the contents of Nt. However, in the ERD, the coefficients of variation (CV) were higher than 12 % in the indicators studied. Jackbean was the legume with the highest value of rumen degradability for the constituents analyzed, while mucuna had lower performance in DM and OM, and centro, in Nt. The results showed that the legumes under study had, generally, high protein contents. This turns them into a favourable alternative as supplement of the diets based on tropical grasses. The highest variations are related to the nitrogen indicators, both in the chemical composition and in the physiological studies of the animal. It is necessary to further study the factors affecting the variability of these indicators, as well as the role played by some secondary metabolites in the optimum use of the nutrients by the animal.