Effects of vitamin C on the structure and function of the digestive system of Andrias davidianus

This experiment aims to study the effect of vitamin C on the growth performance of Andrias davidianus and the structure and function of various organs in the digestive system. Using fish meal, chicken meal, etc. as the protein source and fish oil as the fat source to prepare A. davidianus basal feed, the basal feed was added with 0, 150, 300, 450, 600 and 750 mg/kg of vitamin C (vitamin C phosphate 35% content), formulated into 6 kinds of test feeds with isonitrogen and isolipids, and the initial body weight of (34.14±0.15) g juvenile A. davidianus was reared. The results showed that: the increase in the weight gain rate (WGR) of A. davidianus's vitamin C addition level showed a trend of first increasing and then becoming stable, reaching the maximum when the vitamin C level was 450 mg/kg, which was 102.04%. With the increase of vitamin C level, the activities of pepsin and H⁺-K⁺-ATPase of A. davidianus both increased first and then decreased; and reached the strongest when the vitamin C level was 300 mg/kg; intestinal chymotrypsin, lipase and activity of Na⁺-K⁺-ATPase increased with the increase of vitamin C level and showed a trend of first rising and then tending to be stable, and both reached the strongest when the vitamin C level was 450 mg/kg (P<0.05); it was found through observation of tissue sections when the vitamin C level is 300 mg/kg that it is more conducive to the development of the gastric and intestinal muscle layer and villi of A. davidianus (P<0.05); with the increase of vitamin C level, the activities of CAT, T-SOD, ACP and AKP in the liver of A. davidianus all showed the trend of rising first and then falling. The activity of MDA, AST and ALT showed the opposite trend of change. Moreover, with the addition of vitamin C, the infiltration of inflammatory cells in the liver of A. davidianus was significantly reduced, and the number of macrophages was significantly increased. In summary, proper amount of vitamin C can effectively improve the structure of the digestive tract of A. davidianus, enhance its digestive enzyme activity, improve its growth performance, enhance liver antioxidant capacity, and effectively protect liver health.