Effect of

Cassava (Manihot esculenta) stems, an underutilized by-product with low protein and high crude fiber, have potential as an alternative feed resource for ruminants. This study evaluated the effect of fermenting cassava stems (FCS) with Pleurotus ostreatus and Trichoderma asperellum on in vitro gas production kinetics. A Completely Randomized Design (CRD) with a 3 × 3 factorial arrangement was applied, producing nine treatment combinations, each with three replications. Cassava stems were fermented with P. ostreatus at 0%, 3%, and 6%, combined with T. asperellum at 0%, 1.5%, and 3%. Gas production was measured using sheep rumen fluid at incubation intervals of up to 48 hours, and the following parameters were analyzed: cumulative gas volume and fermentation kinetics. Results showed no significant interaction (P>0.05) between P. ostreatus and T. asperellum for total gas production or kinetic values. The control treatment (without fungi) yielded the highest gas volume: 32.38 ml/500 g at 24 hours and 48.65 ml/500 g at 48 hours. Overall, fermentation reduced gas production, indicating potential benefits for methane mitigation. Additionally, fungal fermentation is expected to enhance fiber utilization and improve the nutritional value of cassava stems as a ruminant feed.