Recycling of Lycium barbarum by-products and bioactive substance application in silage—Insight into antioxidant activity and the regulation mechanism of anaerobic fermentation

Silage, a traditional anaerobically fermented feed primarily used for ruminants, can be enhanced by incorporating Lycium barbarum by-products (LBB) to improve its functional properties. LBB is rich in bioactive compounds with notable medicinal and nutritional benefits, positioning it as a promising alternative to conventional additives. This study investigates the effects of LBB and its bioactive components-Lycium barbarum polysaccharide (LBP), flavonoid (FLA), and betaine (BET) on fermentation parameters, bacterial communities and metabolites in alfalfa silages. LBB, LBP, FLA, and BET significantly increased lactic acid (LA) and water-soluble carbohydrates (WSC) production (P < 0.05), with LBP contributing the highest increases in LA (64.54%) and WSC (70.34%) compared to the control. Furthermore, LBB, LBP, FLA, and BET significantly reduced dry matter loss (DM loss) and ammonia nitrogen (NH3-N) (P < 0.05), with LBB achieving a 70.39% reduction in DM loss and a 35.18% decrease in ammonia nitrogen. The application of these treatments also enhanced the antioxidant properties of silage, as evidenced by increased total antioxidant capacity (T-AOC) and glutathione peroxidase (GSH-Px) levels (P < 0.05). Notably, the relative abundance of Lactiplantibacillus and Pediococcus was elevated in LBB and BET-treated silages, respectively. The bioactive components of LBB demonstrated potent antibacterial activity, with differential metabolites enriched in flavonoid and isoflavonoid biosynthesis pathways. Correlation analysis further revealed relationships between specific metabolites and microbiota. These findings highlight the potential of LBB as a valuable strategy for enhancing silage quality.