Abstract
An 8-week feeding trial was conducted to investigate the regulatory effects of dietary chitosan oligosaccharide (COS), chlorogenic acid (CGA), and thymopeptide (TH) on the growth performance, antioxidant capacity, and metabolism of juvenile Rhinogobio ventralis. A control group (CON) and three treatment groups (COS, CGA, TH) were established, and the underlying molecular mechanisms were analyzed by transcriptomics and metabolomics. The results showed that dietary supplementation with COS, CGA, and TH significantly improved weight gain rate, specific growth rate, and feed utilization efficiency, with COS exhibiting the strongest growth-promoting effect. COS also significantly increased hepatic catalase and superoxide dismutase activities and decreased malondialdehyde content, indicating a marked antioxidant effect, whereas CGA and TH showed no significant effects on these parameters. Transcriptomic analysis revealed significant differences in gene expression profiles among the groups, with commonly enriched pathways including the FoxO signaling pathway, fatty acid biosynthesis, and nicotinate and nicotinamide metabolism. Metabolomic analysis showed that the three additives significantly reshaped the hepatic metabolic profiles: COS mainly activated anabolic metabolism, CGA predominantly suppressed metabolism, and TH exhibited bidirectional regulation, with bile secretion, neuroactive ligand–receptor interaction, and the Fc epsilon RI signaling pathway commonly enriched in all three groups. Integrative KEGG pathway analysis based on transcriptomic and metabolomic predictions further identified the FoxO signaling pathway and neuroactive ligand–receptor interaction as common targets shared by all three additives. In conclusion, COS, CGA, and TH improve the health status of R. ventralis through differential regulation of immune–metabolic networks. Among them, COS is the most suitable feed additive for growth promotion and antioxidant protection in this species.