Effects of VD₃ on survival rate and glucose metabolism ability in Monopterus albus fed a high carbohydrate diet

To investigate the impact of dietary vitamin D₃ (VD₃) on the survival rate and glucose metabolism ability of Monopterus albus fed high-carbohydrate diets, healthy M. albus juveniles (17.13±0.08) g were randomly assigned into 3 groups, each with 4 replicates of 60 fish. The fish were fed diets with normal, high carbohydrate level, and high carbohydrate level supplementing with 2 000 IU/kg VD₃ (referred to as the CON, HC and HCVD₃ groups, respectively). After 8 weeks, no significant differences in growth performance or body composition were observed among the groups. However, The survival rate of HC group (82.22%) was significantly decreased, but after addition of VD3, SR (88.89%) was significantly increased, and the difference was not significant compared with CON group (90.42%). The visceral somatic index (VSI) and condition factor (CF) were significantly higher in the HCVD₃ group than in the HC group. The HC group showed the highest levels of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST), while the HCVD₃ group had the highest serum triglyceride (TG) content. Intestinal amylase and trypsin activities were lower than in the HC group but higher in lipase. Liver glycogen content in HC group (124.45 mg/g) was significantly higher than CON group (99.55 mg/g), as were the activities of hexokinase (HK) and phosphofructokinase (PFK). In contrast, the HCVD₃ group (89.44 mg/g) had lower liver glycogen but higher PFK activity. Muscle PFK activity peaked in the HCVD₃ group. Additionally, catalase (CAT) activities in the liver and intestinal tract of M. albus were lower in the HC group, while total superoxide dismutase (T-SOD) was increased, and malondialdehyde (MDA) activities were decreased with VD₃ supplementation. The HCVD₃ group also showed significantly higher relative expression levels of intestinal proinflammatory cytokines (IL-1β, MyD88), anti-inflammatory cytokines (IL-10) and intestinal compact linking protein genes (ZO-1, ZO-2, Claudin-12) than the HC group. In conclusion, a high carbohydrate diet reduced the survival rate, increased liver glycogen accumulation, reduced antioxidant capacity, and impaired intestinal health in M. albus. Supplementation with 2 000 IU/kg VD₃ mitigated these effects, improving survival and enhancing carbohydrate utilization in fish fed a high-carbohydrate diet. This study provides foundational insights and guidance for glucose metabolism regulation and the artificial feed formulation for M. albus.