From waste to value: Multi-omics reveal pomegranate peel addition improves corn silage antioxidant activity and reduces methane and nitrogen losses

Fermentation technology presents promising opportunities for food waste valorization. Pomegranate peel ( PP ), a food by-product, has potential applications in fermented feed. This study examined the effects of a 6% dry PP additive on the ensiling characteristics, antioxidant activity, metabolites, bacterial community, and in vitro ruminal fermentation, methane (CH 4 ) emission of corn silage ensiled for 7 days and 60 days using microbiome and metabolome analyses. PP-treated silage inhibited ( P  < 0.05) protein degradation by reducing ammonia nitrogen and non-protein nitrogen concentrations during ensiling. The PP additive increased ( P  < 0.05) water-soluble carbohydrate content and reduced ethanol production in corn silage. Lactiplantibacillus dominated PP-treated silage at the initial ensiling stage, while Levilactobacillus prevailed at the final stage . Notably, the PP additive exhibited strong antioxidant activity by modulating antioxidant enzymes and flavonoid biosynthesis mediated by key metabolites (epigallocatechin and catechin). Correlation analysis identified Lactiplantibacillus , Citrobacter , Phytobacter and Burkholderia as key microbes in the production of antioxidant metabolites and enzymes in PP-treated silage. Additionally, PP supplementation reduced ( P < 0.05) in vitro ruminal CH 4 and nitrogen losses, while decreasing dry matter (DM) digestibility in corn silage. In summary, PP-treated corn silage enhanced antioxidant properties and reduced the nitrogen losses and in vitro ruminal CH 4 emissions, but lowered DM digestibility. Thus, PP can be recommended as a silage additive, though the dry PP level should be lower than that used in this study.