Nutritional evaluation of cricket, Gryllus bimaculatus, meal as fish meal substitute for olive flounder, Paralichthys olivaceus, juveniles

Abstract

An 8-week feeding trial was designed to evaluate the potential of cricket meal, Gryllus bimaculatus, as a locally available unconventional source of protein in a practical diet for olive flounder, Paralichthys olivaceus. Three hundred juvenile fish (Initial weight, 33.5 ± 0.01 g) were randomly distributed into five dietary groups in triplicates (20 fish per tank) and each group was hand-fed one of the experimental diets containing graded level of a cricket meal (CR) replacing 0, 20, 40, 60, and 80% of fish meal (FM) protein (designated as CR0, CR20, CR40, CR60, and CR80). Although replacing more than 40% of dietary FM protein resulted in lower growth rates and feed utilization efficiency, juvenile flounders fed the highest level of dietary CR (CR80) still performed as well as control group (CR0). Replacing more than 20% of FM with CR markedly reduced apparent nutrient digestibility in fish. Plasma total cholesterol concentration showed decreasing trend with increasing inclusion levels of CR in the diet. Whole body and fillet lipid content decreased with increasing levels of dietary CR. There was a remarkable enhancement in the levels of C18 fatty acids and reduction in the levels of n − 3 highly unsaturated fatty acids in the fillets of fish fed with the CR diets, which became more prominent with greater levels of dietary FM replacement. Antioxidant enzyme activities tended to increase with increasing dietary CR levels but gradually decreased when the replacement level exceeded 60%. Overall, the efficiency of CR as a promising substitute for FM in the flounder diets has been confirmed not only in relation to growth rates, but also in terms of immunopotency.