Potential of mealworm, Tenebrio molitor, meal as a sustainable dietary protein source for juvenile black porgy, Acanthopagrus schlegelii

Abstract

A 12-week feeding trial was designed to evaluate the potential of mealworm, Tenebrio molitor, meal (MW) as a locally available unconventional alternative source of protein for fish meal (FM) in a practical diet for juvenile black porgy. Five hundred twenty-five healthy fish (initial weight; 6.43 ± 0.00 g) were randomly distributed into five dietary groups in triplicate (35 fish per tank) and each group was hand-fed with one of the experimental diets containing graded level of a MW replacing 0%, 15%, 30%, 45%, and 60% of FM protein designated as MW0, MW15, MW30, MW45, and MW60, respectively. Although replacing 60% of dietary FM protein resulted in lower daily feed intake, juvenile porgies fed the highest level of dietary MW (MW60) still performed as well as control group (MW0). A significant negative trend was detected between fillet lipid content and increasing inclusion levels of MW in the diets. There was a notable reduction in the n-3 highly unsaturated fatty acids (HUFA) in the fillets of fish fed the MW containing diets, which became more prominent with greater levels of dietary FM replacement. Serum lysozyme activity improved with increasing inclusion levels of MW in the diet. Furthermore, expression of the antioxidant enzyme-related genes including glutathione peroxidase (GPx) and catalase (CAT) were markedly upregulated in liver of the fish fed diets replacing FM with MW when compared to fish fed the MW0 diet. Overall, the efficacy of MW as a promising alternative dietary protein source for juvenile black porgy 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.