Effects of dietary inclusion of yellow mealworm (Tenebrio molitor) meal on growth performance, feed utilization, body composition, plasma biochemical indices, selected immune parameters and antioxidant enzyme activities of mandarin fish (Siniperca scherzeri) juveniles

A feeding trial was designed to examine the potential of yellow mealworm, Tenebrio molitor, as a locally available renewable protein source in juvenile mandarin fish feed. Triplicate groups of fish (Initial mean body weight +/- SE.; 20.8 +/- 0.05 g) were assigned to each of four isonitrogenous (50%) and isocaloric (22 MJ kg(-1)) practical diets containing graded level of a full fat yellow mealworm meal (WM) (0, 10, 20, and 30%) at the expense of fish meal (FM) (designated as WMO, WM10, WM20, and WM30). Each group of 20 fish were housed in a 60-L aquarium connected to a closed freshwater recirculating system, with a delivery rate of about 2 L min(-1), and fed twice daily to apparent satiation for a period of 8 weeks. The results revealed that fish growth rates and efficiency of nutrient utilization tended to increase with increasing dietary WM levels from 0 to 20%, and then declined as dietary WM level further increased from 20 to 30%, with the most pronounced effect observed in those of fish fed the WM20 diet. Plasma total cholesterol contents were significantly reduced in fish fed the diet with the highest WM level (WM30). Fish carcass composition did not show any definite pattern of change due to feed composition. Fillets of juvenile mandarin fish fed diets containing WM in place of FM had much higher levels of saturated and monounsaturated fatty acids and lower levels of n-3 polyunsaturated fatty acids (PUFA) than those fed WM-free control diet (WMO). Serum lysozyme and glutathione peroxidase (GPx) activities were found to be significantly higher for fish fed the WM30 diet compared with fish fed WMO diet. Overall, the efficacy of WM as alternative dietary protein source for juvenile mandarin fish has been proved not only in relation to weight gain and efficiency of feed utilization, but also the view point of health-promoting effects in fish.