Converting land-produced organic waste in valuable biomass to be used in the aquatic environment is a good strategy to make aquaculture more sustainable. On this regard, insects represent a very promising example of alternative ingredient to fish meal and fish oil due to their nutritional profile and their bio-converting efficiency; however, their application in aquafeeds still faces possible limitations because of their lack in polyunsaturated fatty acids and the presence of chitin.
In the present study, the concept of circular economy was applied to Black S oldier Fly (BSF) (Hermetia illucens ) rearing, improving the insect's biomass fatty acid composition by culturing them on a land-produced by-product (coffee silverskin ) enriched with a 10% Schizochytrium sp. The insect biomass was then used to formulate five fish diets containing 0, 25, 50, 75 and 10 0% of insect meal with respect to fish meal, respectively . Diets were used for a feeding trial during zebrafish (Danio rerio ) larval development (21 days) and a multidisciplinary approach including biometry, histology, gas chromatography, spectroscopy (FTIR), microbiota analyses and molecular biology was applied to better understand fish responses to the new diets. Results showed that the 50% substitution of fish meal with insect meal represented the best compromise between ingredient sustainability and proper fish growth and welfare. Fish fed with higher BSF inclusions (75 and 100%) showed a severe degree of hepatic steatosis, microbiota modification, a higher lipid content (FT-IR), fatty acid modification and higher expression of both stress and immune response markers.
This study was funded by Ricerca Scientifica Cariverona , NUTRIFISH project N° 2017.0571