EFFECTS OF FARMING SYSTEMS ON SPECIES COMPOSITION, NUTRIENT CONTENT AND DIGESTIBILTY OF FORAGES OF THE NATURAL PASTURE OF ASSOSA ZONE (WESTERN ETHIOPIA)

Abstract

Forage species of the natural pasture of Assosa Zone of Benshangule-Gumuz (Western Ethiopia) were identified and their chemical composition and in vitro dry matter digestibility (IVDMD) determined. Data were collected from two farming systems (shifting cultivation: SC and permanent farming system: PFS) and two grazing types (communal grazing land: CGL, riverside grazing land: RSGL). 18 grasses, 2 legumes, sedge, 2 forbs and 17 trees/shrubs were identified from the natural pasture of both farming systems. Hyparrhenia rufa had significantly lower (P<0.05) NDF and Eleusine floccifolia and Pennisetum catabasis had significantly lower (p<0.05) ADF than those of other grasses. IVDMD of E. floccifolia and Pennisetum catabasis were significantly (P<0.05) higher than that of Chloris pycnothrix, H. rudis, H. rufa, H. collina1, H. collina2 and Sporobolus pyramidalis. Crude protein (CP) content of E. floccifolia was significantly higher (P<0.05) than that of other species except H. hirta. The DM and CP contents of Bauhinia farea were highest (P<0.05) among browse species. Grasses such as C. pychnotrix, H. collina, Digitaria abyssinica, H. hirta, H. rudis and S. pyramidalis were dominant in the study area. Herbaceous biomass production of the CGL in SC was 2,495 kg/ha and that of the RSGL in PFS was 1,244 kg/ha. Continuous overstocking of RSGL decreased the proportion of desirable forage species and encouraged invasion with unpalatable species such as S. pyramidalis and H. collina. It is suggested to study the nutritive value of dominant species, distribution and conservation of highly palatable species and designs for appropriate management interventions.