Dietary quercetagetin enhances antioxidant capacity and modulates intestinal microbiota in dexamethasone-challenged broilers

The study investigates the effects of dietary supplementation with quercetagetin on intestinal antioxidant capacity, antioxidant signaling pathways, and gut microbiota composition in broilers. The results showed that dietary supplementation with quercetagetin significantly enhanced the activities of antioxidant enzymes (SOD, CAT, and GSH) in both serum and intestinal mucosa (P < 0.05), while reducing MDA levels (P < 0.05). Among the tested doses, 100 mg/kg showed the most consistent antioxidant responses. OTU analysis indicated a higher number of unique OTUs in the QG100 group, whereas alpha diversity indices showed no statistically significant differences among treatments. In addition, although the relative abundance of Proteobacteria, a phylum containing many potentially pathogenic bacteria, was decreased in the QG100 group, the difference was not statistically significant. Quercetagetin supplementation significantly improved intestinal development, as evidenced by increased intestinal length and velvety ratio in the jejunum, ileum, and duodenum, particularly at the 100 mg/kg dose (P < 0.05). Based on TMT-based quantitative proteomic enrichment analysis, quercetagetin was hypothesized to upregulate SCP2 protein expression, thereby inhibiting intracellular lipid peroxidation. In conclusion, dietary supplementation with quercetagetin at varying doses can alleviate intestinal oxidative stress and enhance antioxidant capacity in broilers, which is closely associated with the enrichment of fatty acid metabolism-related pathways. Among the tested doses, 100 mg/kg showed the most consistent antioxidant responses.