Dihydromyricetin Alleviates Fermented Rapeseed Meal-Induced Intestinal Injury in Chinese Soft-Shelled Turtle (Pelodiscus sinensis): Insights from Growth, Antioxidant, Inflammatory, Transcriptomic and Metabolomic Assessments.

This study was designed to assess the protective efficacy of dihydromyricetin (DHM) against intestinal injury in Chinese soft-shelled turtles (Pelodiscus sinensis) caused by partial replacement of fishmeal (FM) with fermented rapeseed meal (FRM), and to uncover the molecular mechanisms involved. Turtles were fed an FM-based control diet, an FRM-substituted diet, or FRM diets supplemented with DHM at 0.5‱ (DHMT1), 1.0‱ (DHMT2) or 2.0‱ (DHMT3) for 8 weeks. Growth performance, digestive enzyme activities, antioxidant parameters, inflammatory cytokines, and intestinal histomorphology were assessed, and intestinal transcriptomics and metabolomics were also performed. FRM replacement significantly improved growth performance; however, this beneficial effect was accompanied by notable intestinal mucosal oxidative damage, as evidenced by decreased villus height, increased lumen space, and lamina propria edema, along with elevated pro-inflammatory cytokines (IL-1β and TNF-α) and MDA content, alongside reduced GSH and CAT activities. DHM supplementation dose-dependently ameliorated these adverse effects by restoring mucosal integrity, digestive enzyme activities, redox homeostasis, and inflammatory balance, ultimately improving growth performance. Transcriptomic KEGG analysis revealed that DHM enriched pathways related to glycerophospholipid metabolism, glutathione metabolism, drug metabolis-cytochrome P450, and polyunsaturated fatty acid metabolism. Metabolomics further confirmed dose-dependent remodeling of phospholipids and bile acids. Integrated omics demonstrated that DHM likely regulates detoxification, anti-inflammatory, membrane repair, and antioxidant pathways. In conclusion, DHM demonstrates a protective effect against FRM-induced intestinal mucosal oxidative damage in P. sinensis, which may be mediated by a synergistic combination of enhanced detoxification, anti-inflammatory modulation, restoration of phospholipid membrane integrity, and reinforcement of antioxidant defenses.