Nutrient composition of native forbs of semi-arid and dry sub-humid savannas of Nigeria

A preliminary investigation was carried out to evaluate the nutritive value of six forb species widely used as feedstuffs in West Africa. The study examined four legumes (Crotalaria senegalensis, C. goreensis, Alysicarpus glumaceous and A. rugosus) and two non-legumes (Cassia mimosoides and Ipomea eriocarpa). Field observations on gross phenology of these forbs illustrate their potentials in increasing the range of native forages for use in pasture development or improvement. All species sustained growth on residual soil moisture into the dry season providing green forage when most associated forages had dried up. Results of chemical analysis reveal that the species have properties in terms of contents of protein and some mineral elements that could be advantageously employed to balance animal ration or improve the quality of standing hay of tropical pastures. The species had mean values of 14-18% CP, 3.5-7.0% Ca and 40-58% DMD. Levels of Ca was high and more than 10 times the standard requirements for ruminant production in the tropics. While levels of P, K, Mg and Fe were sufficient, Mn and Na were low, and apparently deficient. The high levels of Ca resulted in unusually wide Ca. P ratios of 16 : 1-33 : 1 among the species. The implications of these findings on uses of the forages in ruminant nutrition and the need for intensive studies on the observed results are discussed. (C) 2000 Elsevier Science B.V. All rights reserved.