Chemical composition, nutritive value and rumen methane potential of some legume tree pods

Abstract

The aim of the experiment was to determine the chemical composition, in vitro gas and methane production and rumen degradable substrate of pods from five leguminous tree species (Leucaena leucocephala, Albiza julibrissin, Robinia pseudoacacia, Acacia karroo and Gleditsia triacanthos) fed to small ruminant animals in Turkey.The pods had adequate levels of crude protein (13-21% in DM), high levels of water soluble DM (30-50% in DM) and moderate levels of NDF (33-51% in DM). Concentrations of condensed tannin were relatively low (0.56-4.3% in DM) except for Gleditsia triacanthos (7.99%). In anin vitro rumen incubation, there was a close relationship (R 2=0.75)) between level of condensed tannin in the pods and methane concentration in the gas for four of the five species. Gleditsia triacanthos with the highest level of condensed tannin (8.0%) and the highest level of methane in the gas (6.2%) did not fit this relationship; the high content of sugars reported for this species may have been the factor contributing to the atypical relationship between the condensed tannin content and methane production. Methane content of the gas was linearly related with rate of gas production (R2=0.91, dry matter mineralized over the 24 h incubation (R2=0.97) and with the content of waCer soluble dry matter in the pods (R2=0.99). The NDF content in the pods was a less reliable measure of methane production (R2=0.78).