Research on Fermentation Characteristics and Microbial Community of Mixed Sorghum-Sudangrass and Sesbania Silage

To explore the optimal mixing ratio and fermentation mechanism of sorghum-sudangrass and sesbania mixed silage, this study prepared silages at ratios of 10:0, 9:1, 8:2, 7:3, and 6:4 and analyzed their chemical composition, fermentation quality, and microbial characteristics on days 3, 30, and 60 of fermentation. The results showed that dry matter (DM) content gradually decreased with prolonged fermentation, with the 7:3 and 6:4 groups maintaining relatively higher mean DM content. The 6:4 and 7:3 groups have more crude protein (CP) content at D60. Water-soluble carbohydrates (WSC) decreased gradually during fermentation. In terms of fermentation quality, pH values decreased progressively and eventually stabilized. Lactic acid (LA) content accumulated over time, with the 10:0 group displaying higher NH3-N/TN content. Butyric acid was not detected in any treatment. Microbiologically, the counts of lactic acid bacteria (LAB) and yeasts gradually decreased with fermentation time, while Escherichia coli and mold were effectively suppressed. Bacterial diversity declined during fermentation, with Firmicutes being the dominant phylum. Weissella predominated in the early stage, while Pediococcus became dominant later. In conclusion, sorghum-sudangrass and sesbania mixed silage promote nutrient preservation and fermentation stability.