Chemical characterization and in vitro methane production of selected agroforestry plants as dry season feeding of ruminants livestock

Abstract

The vagaries in climatic changes disrupt the prevailing weather conditions leading to temperature extremes and protracted rainfall pattern which subsequently affect the quality of forages. Ruminant animals had been implicated as a major source of enteric methane production to the greenhouse effect. Grazing on this low-quality forages extends the time of fattening thereby increasing the amount of methane produced. In this case, effort has been shifted to the feeding of agroforestry plants (browse and tree species) which are available all year round with high nutritive profile. Leaves of selected agroforestry plant species Thevetia peruviana (Pers) K. Schum, Piliostigma thonningii (Schumach.) Milne-Redhead, Spondia mombin L. and Newbouldia laevis (P. Beauv.) Seem were harvested, dried, milled and analysed for their chemical constituents, mineral composition, in vitro and methane gas production. Data collected were analysed using one-way analysis of variance. Significant (p < 0.05) differences were observed in the nutritive value of the selected plants except for dry matter and ether extract contents. NDF values ranged from 606.7 g/kg in T. peruviana to 666.7 g/kg in P. thonngii. P. thonngii recorded the highest value (533.3 g/kg) for acid detergent fibre with the lowest value (500.0 g/kg) observed in N. laevis. There were significantly (p < 0.05) differences among the recorded mineral components of selected plants except for Mn. N. laevis had the highest volume of gas, while P. thonngii had the least. However, N. laevis had the least (p < 0.05) insoluble fibre fraction (b), methane gas production with considerably highest metabolizable energy. With the appreciable level of nutrients, especially in terms of crude protein content and reduced methane production, research into various agroforestry plants will be of high interest to be adopted in ruminant diets.