Effects of Lactobacillus brevis additives on nutrient composition, fermentation quality, microflora structure and metabolites of Pennisetum giganteum silage

Abstract

The current situation of feed resource shortage can be effectively solved by high-value utilization of Pennisetum giganteum. This study investigated the effects of Lactobacillus brevis R-09 on P. giganteum silage quality, microbial structure and metabolites. In a randomized experimental design, silage was treated with (LT: 1.5 × 107 CFU/kg L. brevis R-09) or without (LC: control) inoculant, each replicated six times. The LT group exhibited elevated crude fat (p < 0.05), lactic acid (p < 0.05), and isocaproic acid (p < 0.05) content, alongside reduced crude fiber, butyric acid, and mycotoxin levels (p < 0.05). High-throughput sequencing (16S/18S rDNA) revealed comparable microbial diversity across treatments, with Lactobacillus dominating the bacterial community. Notably, LT increased microbial uniformity and suppressed mold proliferation, diminishing their ecological impact. Liquid chromatography-mass spectrometry (LC–MS) profiling identified 464 differentially abundant metabolites, primarily linked to amino acid and lipid metabolism, suggesting a stabilized metabolic network. Taken together, these results suggest that the addition of L. brevis R-09 can improve the quality of P. giganteum silage by modulating microbial communities and metabolic pathways, thus providing mechanistic insights into the optimization of Lactobacillus-mediated silage fermentation.