DIETARY N-CARBAMOYL GLUTAMIC ACID OR TAURINE ON GROWTH PERFORMANCE, INTESTINAL MUCOSAL MORPHOLOGY AND INTESTINAL MICROFLORA OF HYBRID SNAKEHEAD CHANNA MACULATA ♀× C. ARGUS ♂

This study was conducted to investigate the effects of dietary supplementation with NCG or taurine on intestinal growth, digestion, antioxidant and gut microbiota in juvenile hybrid snakehead (Channa maculata ♀ × Channa argus ♂). A total of 450 hybrid snakeheads with an average initial body weight of (22.02±0.02) g were randomly divided into three groups with three replicates per group and 50 fish per replicate. The fish were fed with basal diet along with three experimental diets supplemented with 0.03% N-carbamoylglutamate (NCG) and 1% Taurine, respectively. The groups were recorded as control group, 0.03% NCG group and 1% Taurine group. The feeding regimen lasted for a duration of 8 weeks. The results showed that dietary supplementation of 0.03% NCG or 1% Taurine led to a significant increase in the protein deposition rate of hybrid snakehead (P<0.05). This supplementation also boosted the activities of intestinal amylase and creatine kinase (P<0.05), promoting the growth of the foregut muscle layer thickness, and the villi (foregut, midgut, and hindgut) (P<0.05). Furthermore, it significantly increased the abundance of intestinal Firmicutes and Mycoplasma (P<0.05), decreased the feed efficiency and intestinal malondialdehyde content (P<0.05), and decreased the abundance of intestinal Fusobacterium and Clostridium (P<0.05). In addition, dietary supplementation with 0.03% NCG significantly increased the total antioxidant capacity and the activities of peroxidase and glutathione peroxidase (P<0.05). It also alleviated the pathological state of the intestine (P<0.05). This supplementation raised the activities of intestinal trypsin, lipase, γ-glutamyltransferase and Na⁺-K⁺-atpase (P<0.05), promoting the growth of anterior intestinal villus length, anterior intestinal villus width and posterior intestinal muscle layer thickness (P<0.05). Additionally, it significantly increased the proportion of intestinal OUT, Chao and Ace index (P<0.05), contributing to enhance the richness and diversity of intestinal flora (P<0.05). The results showed that dietary supplementation of NCG was superior to dietary supplementation of taurine in enhancing intestinal antioxidant activity and alleviating intestinal oxidative damage. However, dietary supplementation of taurine could enhance the activity of intestinal digestive enzymes, improve the richness and diversity of intestinal flora, maintain intestinal homeostasis and promote intestinal growth, and its effect was better than supplementation of NCG.