Dietary inclusion of Pleurotus ostreatus spent mushroom substrate in corn silage-based diets: effects on rumen fermentation, nutrient digestibility, and greenhouse gas emissions using a RUSITEC system

from 65.6 to 14.4 mg/g DM, a reduction of about 78%. Ammonia levels also declined significantly (P < 0.001) from 1025 mmol/g DM in the control to 420 mmol/g DM in the T1 group. Hydrogen sulfide emissions showed a similar pattern (P < 0.001), dropping from 7828 mmol/g DM (control) to 1817 mmol/g DM (20% SMS). Although total volatile fatty acids were not significantly affected, acetate levels increased (P = 0.046) to 74.9% (T2), and valerate was significantly higher (P < 0.001) in the T1 group (2.58%). These results indicate that replacing 10-20% of corn silage with P. ostreatus SMS can significantly enhance nutrient digestibility and reduce environmental emissions, without affecting fermentation characteristics. SMS is an economical, eco-friendly, and promising feed additive for sustainable ruminant farming.