To investigate the effects of various additives on the quality and microbial diversity of mixed silage prepared from tea stems （Camellia sinensis） and broad bean straw （Vicia faba）， mixed at a ratio of 2：8， the experiment comprised one control group （CK） and four treatment groups： T₁ （with Lactobacillus acidophilus added）， T₂ （with Lactobacillus plantarum added）， T₃ （with Bacillus subtilis added）， and T₄ （with a mixture of Lactobacillus plantarum and Bacillus subtilis added）， with three replicates per group. After 60 days of ensiling， the sensory quality， ensiling quality and microbial diversity were analyzed. Results indicated that all the additive treatments significantly improved sensory scores compared to CK （P<0.05）. Compared with CK， all treatment groups exhibited significantly higher concentrations of water-soluble carbohydrates （WSC） and significantly lower pH values （P<0.05）. Crude protein content increased significantly in T₂， T₃， and T₄ （P<0.05）， while the lactate-to-acetate ratio was significantly elevated in T₁， T₂， and T₄ （P<0.05）. Microbial profiling revealed a significant reduction in the relative abundance of certain Lactobacillus operational taxonomic units （OTUs） in T₁， T₂， and T₄—suggesting potential niche competition or functional redundancy among lactic acid bacteria （P<0.05）. Notably， the T₄ group displayed significantly greater phylogenetic diversity （PD_whole_tree index） and alpha diversity （Shannon index） than CK （P<0.05）. Furthermore， principal coordinate analysis indicated that bacterial community composition in T₁， T₂， and T₄ correlated positively with both WSC content and relative feed value （RFV）. Collectively， these findings demonstrate that microbial additives enhance silage fermentation quality and reshape the silage microbiome； moreover， distinct additives confer complementary benefits across key quality and ecological metrics.

Broad bean straw  /  Tea stem  /  Additives  /  Mixed silage  /  Silage quality  /  Microbial community