BackgroundWith its high nutritional value and productivity, Italian ryegrass as a biomass feedstock constantly supplies rumen degradable nitrogen and digestible fiber to ruminants. However, biofuel production is easily reduced during ensiling due to the high-moisture content of Italian ryegrass, leading to economic losses. Lactic acid bacteria inoculants could improve lignocellulosic degradation and fermentation quality and decrease dry matter loss during the bioprocessing of silage. Therefore, this study analyzed the effects ofLactobacillus buchneriTSy1-3 (HE),Lactobacillus rhamnosusBDy3-10 (HO), and the combination of HE and HO (M) on fermentation quality, bacterial community and metabolome in high-moisture Italian ryegrass silage during ensiling.ResultsThe results showed that the pH value was significantly lower in the HO groups than in the other treatments at the end of ensiling, and the dry matter and acetic acid contents were significantly higher in the HO group than in the other inoculated groups. All inoculants decreased the diversity of the bacterial community and significantly increased the relative abundance ofLactobacillus. Inoculation with HO significantly improved the concentrations of organic acids, dipeptides, ferulic acid, apigenin, and laricitrin. Compared withLactobacillus buchneriTSy1-3 (HE), HO significantly upregulated the flavonoid compounds in the flavone and flavonol biosynthesis pathway.ConclusionsOverall, these findings suggest that inoculation with HO was beneficial for the development of Italian ryegrass as a biomass feedstock, improving fermentation quality, accelerating changes in bacterial community composition and increasing biofunctional metabolites in high-moisture Italian ryegrass silage.