Effects of Additives on Fermentation Quality, Nutritional Quality, and Microbial Diversity of Leymus chinensis Silage

This study evaluated how different additives-<i>Lactiplantibacillus plantarum</i> (LP), <i>Lentilactobacillus buchneri</i> (LB), and a composite enzyme (CE)-affect the fermentation quality, nutritional value, and microbial community of <i>Leymus chinensis</i> silage. Fresh forage was wilted to 65% moisture, treated with additives (dissolved in distilled water), and vacuum-sealed in polyethylene bags for 60 days of ensiling. Fermentation parameters and nutritional composition were analyzed using standard methods (e.g., HPLC for organic acids, Kjeldahl for crude protein), and the microbial community was profiled via Illumina MiSeq sequencing of the 16S rRNA gene V3-V4 region. Data were subjected to one-way ANOVA and Duncan's test in SAS. All additives significantly improved key fermentation parameters (<i>p</i> < 0.05). The LP treatment yielded the most favorable profile, with the lowest pH (4.26) and the highest lactic acid (6.52 g/kg DM) and acetic acid (2.58 g/kg DM) contents. LP also best preserved nutrients, showing the highest dry matter (581.62 g/kg FW), water-soluble carbohydrates (24.76% g/kg DM), and crude protein (7.09% DM) (<i>p</i> < 0.05). The CE treatment most effectively degraded fiber, resulting in the lowest acid detergent fiber (428.87% g/kg DM) and neutral detergent fiber (628.43% g/kg DM) (<i>p</i> < 0.05). Additives significantly reduced bacterial alpha-diversity but enriched beneficial phylum such as Bacillota and genus such as <i>Lentilactobacillus</i> spp. LB), while suppressing harmful genera. Correlation analysis confirmed LP was positively correlated with lactic acid and water-soluble carbohydrates (<i>p</i> < 0.0001). In conclusion, additives, particularly LP, enhance silage quality by modulating the microbial community.