Alternative aquafeed options have been explored to improve efficiency and lower production and environmental costs. Soybean meal (SBM) is a major ingredient in aquafeed industry and high inclusion of SBM exhibit soybean induced enteritis in carnivore fish including Atlantic salmon ( Salmo salar ). Black soldier fly (Hermetia illucens) larvae (BSFL) have emerged as a sustainable and viable alternative, demonstrating considerable potential in aquafeed formulations. Previous studies have showcased the positive impacts of BSFL on survival rates, antioxidant capacity, and immune responses in various fish species . Using black soldier fly meal as a complementary ingredient to SBM based diets has been shown to improve performance of rainbow trout in terms of growth performance and health. Therefore, o ur goal was to evaluate the effects of whole black soldier fly larval meal (WBLM ) as complementary feed ingredient in soybean meal based diets on growth performance and gut health in Atlantic salmon .
Seven experimental diets were isonitrogenous (42% crude protein) and isolipidic (20% lipid): fish meal based diet (FM), low level SBM based diets (LS), SBM+5% and 10% WBLM (LS-WB5 and LS-WB10) and high level SBM based diets (HS), SBM+5% and 10% WBLM (HS-WB5 and HS-WB10). A total of 630 Atlantic salmon (15 g) were distributed in 21 tanks (triplicates) in recirculatory aquaculture system.
Results revealed that supplementation of WBLM in soybean meal based diets improved the growth performance of salmon. WBLM exhibited significant positive effects in lo w level of soybean meal based diets whereas high inclusion (10%) of WBLM in high soy bean meal (40%) based diet exhibited negative effects on growth performance of fish. Feed utilization parameters were significantly affected by the dietary treatment. Supplementation of WBLM in high soybean meal based diets improved the feed efficiency compared to non-supplemented groups. The histology of distal intestine was negatively impacted by the high inclusion of soybean meal in salmon, however inclusion of WBLM in soy diets mitigated the gut inflammation in salmon. Gene expression pattern related to gut inflammation is being analyzed. Genes associated to growth performance, gut barrier integrity and acute inflammatory-related cytokines and chemokines, NF-kB and TNF-α-related genes, and regulators of B and T lymphocytes function are being analyzed.
Conclusively, inclusion of whole insect larval meal in soybean based diets improved the production performance and mitigate the gut inflammation in Atlantic salmon for sustainable salmonids production.