Nutritive value and in vitro digestibility of locally available crop residues for ruminants

Abstract:

Crop residues account for over 70% of the basal diet of ruminants in smallholder systems across East African highlands, yet their nutritive profiles are seldom characterised at the local level. This research evaluated six crop residues commonly available in the East Hararghe zone of Oromia — paddy straw, wheat straw, maize stover, sorghum stover, groundnut haulm, and redgram stalk — for proximate composition, fibre fractions, mineral content, and 48-hour in vitro dry matter digestibility (IVDMD). Samples were collected from farmers' fields after the 2023 harvest, dried, milled, and analysed in triplicate. Groundnut haulm recorded the highest crude protein (12.4%) and IVDMD (58.6%), while redgram stalk had the lowest digestibility (38.4%) and highest lignin content (11.8%). Neutral detergent fibre ranged from 54.2% (groundnut haulm) to 78.6% (paddy straw). Maize and sorghum stovers occupied an intermediate position with IVDMD values of 51.8% and 49.2%, respectively. Calcium and phosphorus levels were adequate in leguminous residues but deficient in cereal straws. These data provide a district-specific reference for livestock nutritionists formulating least-cost rations from locally sourced roughages.