Bioprocessing post‐consumer food waste for use as a fish feed ingredient

Post-consumer food waste (FW) is a sustainable source of nutrients that could be used as aquafeed ingredient to decrease aquaculture production expenses. However, FW has a relatively low protein content. Bioprocessing can help improve the nutritional composition of FW prior to using it in aquafeed. The present study assessed the potential benefits of substituting part of juvenile Nile tilapia (Oreochromis niloticus) diets with yeast-fermented oil-extracted FW (FWY). Seven isonitrogenous diets (34% crude protein) were prepared, replacing the standard formulation with 0, 15, 20, 25, 30, 35 and 40% FWY. Juvenile O. niloticus (11.07 ± 0.01 g) were size sorted and stocked into 21 tanks. Each diet was randomly assigned to three replicate tanks, and fish were offered their respective diets for 6 weeks. Results suggest that up to 30% of Nile tilapia feed can be substituted with FWY without significant effect on final body weights and lengths, feed conversion ratio, specific growth rate, hepatosomatic and viscerosomatic indices, body moisture, protein and lipid content of fish. Using an inexpensive ingredient such as FWY to replace 30% of traditional aquafeed ingredients is a promising approach towards decreasing aquaculture production cost without compromising fish growth and welfare.