Lignocellulolytic Enzymes and a Microbial Consortium Improve Lignocellulose Degradation, Fermentation Quality, and Bacterial Co-Occurrence in Forage Oat Silage

This study evaluated the effects of formic acid (A), lignocellulolytic enzymes (E), and a lignocellulose-degrading microbial consortium (M) on fermentation quality, lignocellulose degradation, carbohydrate conversion, bacterial community, and potential microbial associations in forage oat silage. Fresh forage oat was treated with Lactiplantibacillus plantarum alone (control) or combined with A, E, or M and ensiled for 60 days with three biological replicates per treatment. All additives improved silage fermentation quality. Compared with the control, E and M significantly increased lactic acid content, reduced pH, and decreased ammonia-N accumulation. E exhibited the highest water-soluble carbohydrate content (26.37 g/kg DM) and achieved the greatest degradation extent of hemicellulose, cellulose, and ADL, accompanied by increased release of glucose, fructose, and xylose. LEfSe and correlation analysis suggested that carbohydrate-utilizing bacteria and LAB-related taxa were closely associated with lignocellulose degradation, xylose release, and lactic acid production. M exhibited the highest observed co-occurrence network complexity, suggesting altered potential associations among bacterial taxa during ensiling. E primarily improved silage quality by promoting lignocellulose degradation and increasing carbohydrate availability, whereas M was associated with improved fermentation characteristics and changes in bacterial community composition and co-occurrence network complexity. These findings highlight lignocellulolytic enzymes and microbial consortia as effective strategies for improving lignocellulose utilization and fermentation quality in forage oat silage.