Forage yield and quality profile of three annual legumes in the tropical highlands of Ethiopia
Keywords:Forage quality, Annual legume, Tropical highland, Ethiopia
AbstractEthiopia has the greatest concentration of Trifolium species in sub-Saharan Africa. These species have the potential to improve natural or sown pastures in the tropical highlands of Africa. The objective of this study was to evaluate the yield and quality of three annual forage legumes at different growth stages, all grown at an altitude of 2390 m above sea level in the tropics. Two indigenous clovers, quartin clover (Trifolium quartinianum A. Rich.) and rueppell clover (Trifolium rueppellianum Fres.), and one introduced legume, woolypod vetch (Vicia villosa subsp. dasycarpa Roth), were sown in a black clay Vertisol for two years. Quartin clover and woolypod vetch attained maximum dry matter (DM) yields of 5.53 and 6.37 Mg ha-1, respectively, at the pod stage, while the maximum for rueppell clover was 4.72 Mg ha-1 at flowering. For all species, maximum accumulation of in vitro digestible DM (IVDDM) corresponded with DM accumulation, while maximum accumulation of crude protein (CP) occurred at the flowering stage. At most harvest stages, the clovers had greater IVDDM but less CP concentrations than woolypod vetch. Woolypod vetch had a greater concentration of acid-detergent fibre (ADF) and neutral-detergent fibre (NDF) than the clovers through flowering. At later stages, however, woolypod vetch had less or the same fibre content as the clovers. In all species, ADF and NDF increased while CP and IVDDM concentrations decreased with maturity in total herbage and stem fractions. In leaf fractions these parameters changed very little with maturity.