Dietary substitution of fishmeal by yellow mealworm and its effects on growth and metabolism-related gene expressions in Acipenser stellatus

Yellow mealworm, Tenebrio molitor (Y-MW) was replaced at 5%, 10% and 20% ration levels with fish meal in the diet of the stellate sturgeon, Acipenser stellatus in view of reducing the consumption of fish meal and after that the effects of this replacement were investigated. Fish were fed four dietary regimes in three replicates for two months including: CTRL: fish fed a diet containing full fish meal diet, M5: fish fed a diet substituted by 5% full fat Y-MW, M10: fish fed a diet substituted by 10% Y-MW, M20: fish fed a diet substituted by 20% Y-MW for 2 months. Y-MW at substitution level of 10-20% increased WG and FW, although the FCR values showed an improvement than control only in the fish of 10% Y-MW (P < 0.01). Use of Y-MW, especially at 10-20% substitution levels stimulated the expression of genes involved in growth, energy metabolism and immunity (P < 0.01). Dietary Y-MW had no effect on the concentration of liver metabolic enzymes in serum (P > 0.01). The lysozyme activity elevated in response to 10-20% Y-MW compared to the control fed fish (P < 0.01). The Ig levels showed a significant increase in all Y-MW treated groups compared to the control fed fish, in which the highest levels were observed in fish of 20% Y-MW (P < 0.01). Y-MW also affected some immune components of mucus. SDS-PAGE analysis of mucus proteins suggested some differences in protein profiles of the control fed and Y-MW fed fish. The pattern and intensity of the protein bands changed in response to dietary Y-MW. The results of the present research showed that the replacement of fish meal up to 10-20% by Y-MW in the diet of the stellate sturgeon can even improve growth and immunity.