Chemical composition, secondary metabolites, in vitro gas production characteristics and acceptability study of some forage for ruminant feeding in South-Western Nigeria
Studies were conducted to evaluate the nutritive value of eight selected forages (Tridax procumbens, Merremia aegyptia, Aspilia africana, Tithonia diversifolia, Alchornea cordifolia, Alchornea laxiflora, Synedrella nodiflora, and Newbouldia laevis) consumed by ruminants in South-Western Nigeria. Chemical composition and qualitative analysis of saponins, phenol and steroids of the plants were determined. In vitro gas production (IVGP) was carried out for 72 hours on the plants. Metabolizable energy (ME), Organic matter digestibility (OMD) and Short chain fatty acids (SCFA) were predicted and methane (CH4) was measured. Five of the plants were subjected to acceptability study using cafeteria method. The result of the chemical composition revealed that M. aegyptia had the highest value of CP (22.09 %) while Tridax procumbens had the lowest (10.50 %). A. africana had the highest content of Calcium, Phosphorus and Zinc with values of 3.10 %, 0.93 % and 39 ppm respectively. The analysis of secondary metabolites showed that A. africana, T. diversifolia and S. nodiflora were high in saponin while A. cordifolia, A. laxiflora, T. diversifolia and A. africana were implicated for condensed Tannin. N. laevis recorded a high level of steroids. Results showed significant variations in the values of IVGP, ME, OMD, SCFA and CH4 obtained for the plants. The order of preference of the plants by the calves were M. aegyptia>A. cordifolia > N. laevis > A. laxiflora> T. diversifolia. The study revealed that the forages are rich in crude protein as well as micro and macro minerals. They are also rich in highly fermentable carbohydrates which affirm them as ruminant feed resource.
Keywords: Acceptability, chemical composition, in vitro gas production, forages , south-western Nigeria