Abstract

This study focused on the modification of oncom making based on cassava (Manihot esculenta) pulp to improve the nutritional profile through fermentation by Neurospora sitophila and enrichment with a mixture of urea (0, 2.5, 5, 7.5, and 10 of dry matter) and a nitrogen:sulfur ratio of 15:1 (oncom cassava pulp= OCP). Hence an investigation was carried out on the in vitro digestibility and fermentability of OCP when included in sheep diets. In vitro evaluation (diet oncom cassava pulp; DOCP) was carried out on diets consisted of a mixture of 50 grass and 50 concentrate containing 2.5OCP (which selected based on the highest analysed crude protein and crude fiber levels when compared to the nutrient contents of other enriched OCP levels, P < 0.001) with compositions of 0, 10, 20, and 30 of DOCP. Results showed that the higher use of urea and nitrogen:sulfur ratio caused a decrease in crude fiber and gross energy and an increase in nitrogen-free extract (NFE) levels (P < 0.001). Using 2.5OCP in the diet resulted in significantly different N-ammonia (N-NH3), volatile fatty acid (VFA), in vitro dry matter digestibility (IVDMD), and in vitro organic matter digestibility (IVOMD) (P < 0.05), except for total gas and ruminal pH values. The highest IVDMD and IVOMD were obtained in 30 DOCP with a close N-NH3 and VFA and within the normal range. In summary, CP fermentation by Neurospora sitophila which is enriched with a mixture of 2.5 urea and nitrogen:sulfur at a 15:1 ratio can be used in sheep diet up to 30. © The Author(s) 2025