Supplements enhance antioxidant activity and improve the quality of whole-plant corn silage by altering secondary metabolic pathways and phenolic metabolite composition

Whole corn silage (WCS) is prone to deterioration during storage, but appropriate supplements can enhance active metabolites, preserving silage quality and feeding value. This study compared the metabolic responses of WCS treated with Lactobacillus buchneri (LB), plant-derived melatonin (ME), and their combination (LB + ME) by evaluating fermentation quality, antioxidant indices, and active metabolites. LB and ME significantly increased superoxide dismutase and catalase activities ( P  < 0.05) and improved 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric ion-reducing antioxidant power (FRAP) radical scavenging capacities, enhancing overall antioxidant capacity. Metabolomics analysis identified 1449 secondary metabolites in WCS, with LB and ME affecting the synthesis of flavonoids, particularly sinapic acid, 1,2,5,7,8-pentahydroxy-3-methylanthracene-9,10-dione, and 2,4-dihydroxybenzoic acid. A positive correlation was observed between water-soluble carbohydrates, DPPH, FRAP, SOD, chrysoeriol, and kaempferide in LB-treated WCS. In conclusion, LB exhibited superior antioxidant activities and promoted flavonoid synthesis. The findings of this study provide mechanistic insights into how supplements influence antioxidant pathways in WCS.