In-vitro gas production kinetics and methane emission potential of selected indigenous legume fodder tree and shrubs in the semi-humid condition of the southern Ethiopia

Abstract

The aim of the study was to determine the in-vitro gas production characteristics and methane emission potential of the indigenous legume fodder tree and shrub (ILFTS). The most common 11 ILFTS species were selected and the leaves, fruit and pod samples were collected, oven dried and ground for experimental analysis. The potential leaf biomass yield was estimated by measuring the stem diameter. The contents of dry matter (DM), organic matter (OM), ether extract (EE), crude protein (CP), acid detergent lignin (ADL), Ash, total phenolic (TP) and condensed tannin (CT) were analyzed. The Gross energy (GE), digestible crude protein (DCP), digestible energy (DE), total digestible nutrient (TDN), digestible carbohydrate (DCHO), digestible crude fat (DCF) and metabolizable energy (ME) were estimated. In-vitro gas production technique was used to determine the gas production characteristics and methane emission potential of the ILFTS. Metabolizable energy (ME, MJ /Kg DM), organic matter digestibility (OMD) and short-chain fatty acids (SCFA, µmol) were calculated using the values of proximate analysis and gas volume. The study indicated a wide variation in the nutritional value parameters among the ILFTS species. The potential leaf biomass yield, nutritive quality, gas volume, gas production characteristics and methane emission potential, OMD, ME, and SCFA revealed significant variation with species and agroecological zones. Moreover, GE, TDN, DE, TP and CT showed negative correlation with the gas volume unlike methane which showed positive correlation. In general, the gas volume, gas production characteristics and methane emission of the ILFTS species depends on their chemical and cell wall composition. Thus among the ILFTS species examined Acacia hocki leaf and Acacia tortilis pod in the lowland excelled in their nutritional quality for feeding ruminants however the midland species had comparable qualities.