CHEMICAL COMPOSITION AND ITS RELATIONSHIP WITH IN VITRO METHANE MITIGATION POTENTIAL OF SELECTED WILD LEGUME SEEDS

Abstract

Background. Increasing atmospheric concentrations of methane (CH4) have led scientists to examine its sources of origin. Mitigation of enteric CH4 production by ruminants has been recognized as an important goal because it reduces greenhouse gas emission and improves feed efficiency. Objective. The study evaluated the chemical composition and its relationship with in vitro total gas (GP24) and in vitro methane (CH4) production parameters of five tropical wild legume seeds [(Luffa cylindrica (LC), Piliostigma thonningii (PT), Detarium microcarpum (DM), Daniellia oliveri (DO) and Afzelia africana (AA)]. Methodology. Chemical compositions were analysed, while total GP volume was measured and CH4 estimated after 24 h incubation. Results. Total GP24 produced by the seeds steadily increased and was most pronounced (P<0.05) in AA seed meal (64.71 mL/200 mg DM), and the least in LC (37.83 mL/200 mg DM). CH4 concentration (MC) varied (P<0.05) from 9.90 in AA to 23.93 in LC. Methane reduction potential (MRP) was higher (P<0.05) for AA seed meal and lowest for LC. There were positive correlations (r = 0.685**, r = 0.763* respectively) between crude protein and non-fibre carbohydrates (NFC) contents of the seeds and total gas production at 24 h incubation. Fibre fractions (NDF and ADF) were positively, (r = 0.978 and r = 0.874 respectively) correlated with MC, and negatively (r = - 0.927 and r = - 0.870, respectively) associated with total GP24 and MRP. CP, EE and NFC had a more pronounced positive correlation (r = 0.948**, r = 0.851** and r = 0.852** respectively) with MRP. Implication. Results suggest that all the selected seeds have the potential to reduce methane production and positively impact rumen fermentation. Conclusion. Seed containing more nutrients (CP, EE, and NFC) reduced enteric methane production more than any other of the chemical components in the study.