Effect of partial dietary replacement of fishmeal by yellow mealworm (Tenebrio molitor) larvae meal on the innate immune response and intestinal antioxidant enzymes of rainbow trout (Oncorhynchus mykiss).

The present study investigated the effects of 25 and 50% dietary inclusion of yellow mealworm, Tenebrio molitor (TM), larvae on the intestinal antioxidant enzymes, lipid peroxidation and immune system of rainbow trout, Oncorhynchus mykiss. Fish were fed for 90 days with a control diet (TM0) or with 2 test diets (TM25 and TM50) where 35 and 67% of the fishmeal was replaced by TM larvae meal respectively. At the end of the growth trial, humoral immune parameters were assessed in the sera of the fish and the activities of antioxidant enzymes were measured in intestine homogenates. The present results show a strong increase of the activity of the antioxidant intestinal enzymes and reduction of lipid peroxidation. Increased trypsin inhibition and faster antibacterial activity of the serum were also detected. These evidences could be due to the physiological similarities between the exoskeleton of parasites and insects. The present findings reinforce the previous results which revealed a positive effect of the dietary TM on rainbow trout growth and further confirm its adequacy for fishmeal partial replacement in aquafeed.