DIETARY GLUTAMIC ACID, GLUTAMINE AND MONOSODIUM GLUTAMATE ON FEEDING, GROWTH, GASTROINTESTINAL AND LIVER FUNCTION OF MANDARIN FISH (SINIPERCA CHUATSI)

This study aims to investigate the effects of glutamate (Glu), glutamine (Gln), and monosodium glutamate (MSG) on the growth and gastrointestinal function of mandarin fish (Siniperca chuatsi). Six treatment groups were established with varying concentrations of Glu, Gln, and MSG, along with a control group (CON). The fish, with an initial body weight of (17.60±0.53) g, were fed for 56d. Compared to the CON group, the results indicated the following: All three additives significantly increased food intake, with MSG exhibiting the most pronounced effect; Glu-0.2 and Gln-0.2 significantly improved the weight gain rate (WGR) and feed efficiency ratio (FER); Glu-0.2, Glu-0.4, and Gln-0.2 significantly increased the activity of pepsin and gastric H⁺-K⁺-ATPase in each addition group; Glu-0.2 promoted the activity of intestinal trypsin; Na⁺-K⁺-ATPase activity did not promote Gln-0.4, but was significantly increased in other groups; Glu and MSG groups showed significant reductions in plasma D-LA, ET and DAO activity; Gln group exhibited significantly increased plasma AST and ALT levels, accompanied by noticeable hepatocyte swelling and vacuolation; Glu and MSG groups demonstrated significantly enhanced plasma antioxidant capacity, while Gln group experienced a decrease; Glu-0.2 group showed significantly higher abundances of Tenericutes and Cetobacterium compared to the CON group. In conclusion, Glu has a positive positively influence on mandarin fish by promoting gastric acid secretion, gastrointestinal digestion, and absorption, fortifying intestinal physical barrier, enhancing intestinal flora, and supporting growth; Gln improves the gastrointestinal function of mandarin fish but leads to a decrease in the antioxidant capacity of body, along with damage to liver function; MSG stands out in promoting feeding and growth but does not significantly improve feed conversion.