Solid-state fermentation (SSF) offers a promising approach to enhance the nutritional value of abundant but underutilized agro-industrial by-products in sub-Saharan Africa. The study investigated the effect of SSF using Pleurotus ostreatus on rice bran (RB), rice husk (RH) and maize cob (MC). The design used was a 3 × 3 factorial arrangement of treatments in a completely randomized design (CRD). The factors were three substrates (RB: rice bran, RH: rice husk, and MC: maize cob) and three fermentation periods (0, 30, 45 days). Unfermented and fermented samples were analysed for dry matter (DM), crude protein (CP), ether extract (EE), ash, crude fibre (CF), neutral detergent fibre (NDF), acid detergent fibre (ADF), and acid detergent lignin (ADL). In vitro gas production (3-96 h) was measured using rumen liquor. In vitro organic matter digestibility (IVOMD), metabolizable energy (ME), net energy (NE), short-chain fatty acids (SCFAs), and microbial protein (MP) were estimated using established models. Significant differences (P < 0.05) in CP and EE contents were observed among RB, RH, and MC within fermentation periods. The CP contents at days 30 and 45 were 9.44%, 8.10% for RB, 3.07%, 4.69% for RH, and 5.32%, 12.19% for MC, respectively. Fibre fractions varied among substrates at each fermentation period, with NDF differing among RB, RH, and MC, and ADL showing significant differences among substrates at day 30. Potential gas production (b) rose in MC (52.7 ml) and RH (53.9 ml) after 45 days. The rate of gas production (c) ranged from 0.03-0.08 h⁻¹ at day 0 and 30, but after 45 days, RH reached 0.08 h⁻¹, while RB and MC slowed to 0.01 h⁻¹. IVOMD, ME, NE, SCFA and MP were all higher in fermented RH and MC, with peak improvements at day 30. The study results indicated that SSF for 30-45 days could improve the nutritional value of agro-industrial by-products. Keywords: Chemical composition, In vitro gas production, Maize cob, Rice bran, Rice husk, Oyster mushroom, Solid-state fermentation.
AFRAM et al. (Mon,) studied this question.