This study was carried out to determine the quality and in vitro digestibility of dried cassava peel, mushroom degraded cassava peel when mixed with 40% of silage from guinea grass and the grass at different levels. Samples from dried cassava peel, mushroom degraded cassava peel (SMS), silage and grass was collected and the nutritional potential was investigated by determining the chemical composition and the level of digestibility. The result shows that there was a significant difference (P < 0.05) on the in vitro gas production of dried cassava peel, mushroom-degraded cassava peel and when mixed with 40% of silage from guinea grass and the grass at different levels. The highest gas production of whole samples was from 100%CP having the (P < 0.05) value of 56.25 mL/200 mg of DM and the lowest was from which had the (P < 0.05) value of 26.50 mL/200 mg of DM. The highest gas production of diets was from Diet 6 (40% grass + 50% cassava peel + 10% PKC) having the (P < 0.05) value of 59.00mL/200mgDM and the lowest was from Diet 2 (40% silage + 50% cassava peel + 10% PKC), which had the (P < 0.05) value of 17.50 mL/200 mg of DM. Diet 6 had the highest values for metabolizable energy (ME), organic matter digestibility (OMD) and short-chain fatty acids (SCFAs; 7.26 MJ·kg⁻¹, 59.93% and 0.82 μmol respectively). Diet 3 has the lowest value for ME, OMD and SCFAs (3.84 MJ·kg⁻¹, 35.79% and 0.22 μmol respectively). The highest methane gas production of whole samples was from 100%CP having the (P < 0.05) value of 26.33 mL and the lowest was from 100%SMS which had the (P < 0.05) value of 12.88 mL. The highest gas production of Diets was from Diet 1 having the (P < 0.05) value of 25.00 mL and the lowest was from Diet 3 which had the (P < 0.05) value of 11.25 mL. The diet having 40% grass + 50% cassava peel + 10% PKC had the highest nutritional qualities. It is therefore concluded from this study that the use of cassava peel as substrate for producing edible mushroom improved the potential feeding value of the resultant substrate.