PROMISING TROPICAL GRASSES AND LEGUMES AS FEED RESOURCES IN CENTRAL TANZANIA IV - EFFECT OF FEEDING LEVEL ON DIGESTIBILITY AND VOLUNTARY INTAKE OF 4 HERBACEOUS LEGUMES BY SHEEP

An experiment involving comparison of 4 legumes fed at 5 levels was co nducted to study the effect of the level of feeding on digestibility a nd voluntary intake by Blackhead persian rams. The legumes were Neonot onia wightii cv. Mpwapwa (NWM), Stylosanthes scabra cv. Seca (SSS), Ma crotyloma axillare cv. Archer (MAA) and Macroptilium atropurpureum cv. Siratro (MAS). The forages were cut at 8 weeks and dried in the sun. Sixteen sheep were used and fed 600, 900, 1200, 1500 and 1800 g/day in a split plot design. Among the species compared, SSS and NWM had high er (P < 0.05) organic matter (OM) digestibility than MAA and MAS. Diff erences in intakes among species were observed, with MAS having lower OM intakes (P < 0.05) than the other species. Increasing feeding level allowed the selection of more leafy diet with significant improvement (P < 0.05) in OMD in SSS, and MAA, but not of MAS and NWM. Significan t improvement (P < 0.05) in intakes of OM and digestible OM were obser ved in all species, as feeding level was raised from 600-1800 g per da y, to allow for the selection. The level of feeding allowing maximum i ntakes of OM with the least refusal was, on the average, 1200 g with 1 9.6% refusals, ranging from 900 g per day with refusals of 10.3% for M AS, to 1500 g per day with refusals of 29.4% for SSS. The maximum OM i ntakes were 20.5 g kgW(-1) d(-1) and 25.5 g/kgBW/day for MAS and SSS, respectively. Estimated maximum intake: at infinite feeding level was. on the average. 26 g/kg BW/day. A realistic value for SSS could not b e obtained, bur was, probably, considerably higher than that for the o thers. To obtain a maximum value for animal production, refusals of ap proximately 40% would be required. Among the legumes studied. SSS seem s to be the most promising species for the semiarid areas of Central T anzania. (C) 1998 Elsevier Science B.V.