Dietary ferulic acid improved growth performance, health status, digestive capacity, and glycolipid metabolism of juvenile Chinese Mitten Crab (Eriocheir sinensis) fed with low fish meal diets

High plant protein diets can induce oxidative stress and tissue damage, disrupt glucose and lipid metabolism, and ultimately impair the growth of aquatic animals. This study examined the effects of ferulic acid on growth performance, health status, digestive function and glycolipid metabolism in juvenile Eriocheir sinensis fed a high plant protein diet. A total of 960 juvenile crabs (mean weight: 0.50 ± 0.02 g) were randomly allocated to six experimental groups and fed either a control diet (35 % fishmeal) or low fishmeal diets (15 % fishmeal, with concentrations of 0, 40, 80, 160, and 320 mg/kg ferulic acid) for 56 days. Compared with juvenile crabs fed high-fishmeal diets, those fed low-fishmeal diets exhibited reduced weight gain rates and impaired antioxidant capacity, digestive function, and glucose-lipid metabolism. But compared to the low-fishmeal control group, the inclusion of 80–160 mg/kg ferulic acid showed the higher weight gain rate and higher specific growth rate of juvenile crabs, and lowered the feed conversion ratio. Ferulic acid supplementation at levels of 40–160 mg/kg enhanced total antioxidant capacity (T-AOC) in the hepatopancreas, reduced aspartate aminotransferase (AST) levels in hemolymph, and decreased malondialdehyde (MDA) levels in the hepatopancreas. Additionally, a 160 mg/kg ferulic acid supplementation improved the histology of intestinal tissues. Ferulic acid also promoted lipid biosynthesis, causing a substantial rise in the crude lipid content of the whole crab, as well as elevated hemolymph triglyceride (TG), cholesterol (TCHO), and high-density lipoprotein (HDL) levels. Furthermore, ferulic acid upregulated the expression and activity of key genes and enzymes involved in glycolysis, gluconeogenesis, and the pentose phosphate pathway. Conversely, the expression of glycogen synthase (gs) and glycogen phosphorylase (gp) was downregulated. In conclusion, supplementation with ferulic acid in a high plant protein diet significantly enhanced the growth, health, and lipid accumulation in juvenile crabs, while also promoting the utilization of carbohydrates for energy production. According to the regression analysis of weight gain rate and crude lipid content, the optimal supplementation range of ferulic acid was determined to be 123.90–126.09 mg/kg.