The replacement of fishmeal (FM) by insect meal (IM) in aquafeed formulation has been thoroughly studied lately, but little is known about their impact on nutrient metabolism of fish. This study evaluated the impact not only of partial but also total FM replacement by IM on intermediary metabolism of European sea bass (Dicentrarchus labrax). A fishmeal-based diet was used as a control (CTRL) and two other diets were formulated to include 20% and 40% of defatted Tenebrio molitor larvae meal (dTM), replacing 50% (TM50) and 100% (TM100) of fishmeal (FM), respectively. After a 16-week feeding trial, a multidisciplinary approach including assessment of histological, biochemical, molecular, and enzymatic parameters was adopted to investigate hepatic and plasmatic responses to the different dietary formulations. The results obtained demonstrated that dTM can be successfully used to replace 50% of FM in diets for European sea bass, without adversely affecting liver health or intermediary metabolism of nutrients. As for TM100, although no signs of steatosis were observed in the liver, the activity of glycolytic and lipogenic genes and enzymes increased when compared to CTRL diet (P < 0.05), resulting in higher levels of plasmatic non-esterified fatty acids and triacylglycerides (P < 0.05), which in the long-term may compromise fish health, thus precluding such a high degree of substitution for use in practical diets for European sea bass.
Keywords: animal nutrition; hepatic genes and enzymes; insect meal; intermediary metabolism; metabolites.
Insect meal has been increasingly considered as novel protein source in diets for different animal models, including fish. European sea bass is one of the most important fish species in Europe, particularly in the Mediterranean. Fishmeal is considered a premium protein source in diets for aquaculture fish. Thus, this study evaluated the impact of partial and total fishmeal replacement by an insect meal (defatted Tenebrio molitor larvae meal) on intermediary metabolism of European sea bass. After 16 weeks of feeding, the results obtained demonstrated that selected insect meal can be successfully used to replace 50% of fish in diets for European sea bass, without adversely affecting liver health or intermediary metabolism of nutrients. On the other hand, total fishmeal replacement by insect meal may compromise fish health in the long-term.
© The Author(s) 2023. Published by Oxford University Press on behalf of the American Society of Animal Science.