Chemical composition, protein fractionation and rumen digestion of mucuna (Stizolobium aterrimum) components.

Samples of mucuna (Stizolobium aterrimum) in vegetative stage were taken to study the chemical composition, protein fractions and the rumen digestion of nutrients (DM, OM and CP) through the method of nylon bags in situ. Different solvents were used for the fractioning of the proteins: albumin (H2O), globulins (NaCl 5%), prolamins (ethanol 80%) and glutelins (NaOH 0.2%). The nutrients degradability values were adjusted to the model: P = a + b [1-e(-c*t)]. The following equation was used for the rumen effective degradability (ED): ED = a + (b*c)/(c + k), with different rates of rumen turnover (0.03, 0.04, 0.05) and different incubation times (6, 8, 12 and 48 h). The protein fractioning of this legume indicated that glutelin was the most represented, with almost the double of albumin and the triple of globulin and prolamin. The effective degradability of DM, OM and CP (N x 6.25) reached values between 37.55-49.9, 41.7-53.41 and 36.74-48.19%, for different rates of rumen turnover (0.03 and 0.05), respectively. The dynamics of the in situ rumen degradation of the indicators increased progressively in time up to the last schedule of incubation established in the experiment and for all the components, in decreasing order (OM, DM and CP). Results showed a correspondence between the protein fractioning and the rumen degradability of the proteins, in regards to the amount of protein of low degradability such as glutelins. [ABSTRACT FROM AUTHOR]