Mixed Fermentation of Rice Straw with Pleurotus eryngii Spent Mushroom Substrate: Effects on Silage Quality, Microbial Community and In Vitro Fermentation Characteristics
The objective of this study was to evaluate the effects of mixing Pleurotus eryngii spent mushroom substrate (SMSP) with rice straw on silage quality, microbial community, and in vitro rumen fermentation characteristics for beef cattle production. A completely randomized design was used with four treatments: (1) 100% rice straw (RSC); (2) 90% rice straw + 10% SMSP (RS100); (3) 80% rice straw + 20% SMSP (RS200); and (4) 70% rice straw + 30% SMSP (RS300). After 60 days of fermentation, nutrient contents, fermentation quality, aerobic stability, microbial community (16S rRNA gene sequencing), and in vitro fermentation parameters were evaluated. SMSP addition significantly (P < 0.05) improved crude protein content, in vitro dry matter, crude protein and fibre digestibility, sensory quality, fermentation attributes, and aerobic stability of the silage. The SMSP treatment also reduced the relative abundance of Acetobacter and increased the relative abundance of Pediococcus, Weissella, and lactic acid bacteria as revealed by 16S rRNA gene sequencing. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt2) analysis predicted that SMSP treatment altered the metabolic functional profiles of the silage bacterial community, including carbohydrate metabolism and lipid metabolism pathways. Higher inclusion levels of SMSP (RS300) resulted in the most pronounced improvements. These results indicate that co-ensiling rice straw with SMSP is an effective strategy for enhancing silage nutritional value, improving feed digestibility, and promoting resource recovery from agricultural solid waste, which provides a useful reference for sustainable beef cattle production.