Evaluation of forage quantity and quality in the semi-arid Borana Lowlands, Southern Oromia, Ethiopia

Abstract

This study was conducted with the aim of determining herbaceous biomass during different seasons, plus nutritive value of herbaceous species and forage on selected woody plants and documenting pastoralists’ perceptions of the value of various forage species in Borana Zone, Oromia, Ethiopia. Data were collected from a total of 92 main plots of 500 m2 during rainy and dry seasons located across different functional Land Use Units called Kalo (enclosed areas), Worra (grazed by lactating stock) and Foora (more remote and grazed by dry and non-lactating stock). Total herbage and leaves of woody plants were analyzed for concentrations of crude protein (CP), organic matter (OM), neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL) and ash. Perceptions of farmers were determined through group discussions. Herbage biomass plus chemical composition of both herbaceous and woody forage species varied significantly across seasons and Land Use Units. Mean herbaceous biomass in all Land Use Units was poor (876–1,469 kg DM/ha). Mean CP, NDF and ADF concentrations of the herbaceous samples were 62, 749 and 444 g/kg DM, respectively. Mean CP% of leaves from woody plants was higher (11%) than from herbage (6%). In both groups, crude protein concentrations were highest during the wet season and lowest during the dry season, whereas fiber concentrations were highest in the dry season. Mean CP% of herbaceous forage species was below the critical level recommended for both beef cattle (7%) and small ruminants (9%) but forage from woody species should provide a reliable supply of supplementary nitrogen. Management of rangelands should be designed to ensure that desirable herbaceous species are preserved, while desirable woody species are also a valuable asset. Determination of management strategies to ensure that the desirable mix of species is maintained is imperative if sustainable production is to continue.