Different Commercial Microbial Additives Influence Fermentation Quality and Microbial Community of King Grass Silage

The microbiota in forage silage plays a pivotal role in determining the fermentation quality. Identifying effective microbial additives is essential to help forage producers refine their search for functional inoculants and to support farmers in adopting them for practical ensiling. This study investigated microbial and metabolomic dynamics in king grass silages treated with six commercial inoculants dominated byEnterococcus faecium-like species,Bacillus velezensis, andLactobacillus paraplantarum. The fermentation characteristics, viable microbial diversity, and metabolite profiles were compared between treated and untreated silages using 16S rDNA sequencing and metabolic profiling via LC-QTOF-MS, integrated with multi-omics correlation analyses. Additive-treated silages showed improved fermentation quality, simplified bacterial correlation networks, and distinct microbial successions and interactions. A total of 1523 metabolites were detected, with 56–84 significantly altered in each treated group compared to the control. Metabolites with antimicrobial, antioxidant, and cholesterol-lowering activities were more abundant in treated silages, especially organic acids, amino acids, and short-chain fatty acids. Inoculants distinctly influenced amino acid, energy, nucleotide, and vitamin metabolism during ensiling. This study advances our understanding of how commercial microbial additives reshape the bacterial community structure and function in silages and highlights promising lactic acid bacteria species contributing to silage quality through the production of bio-functional metabolites.