Replacing fishmeal with new alternative protein sources in the diet of European sea bass (Dicentrarchus labrax): effects on fish growth and disease resistance

Abstract

Due to the natural limit found in overexploitation of fishing, and the increased demand of aquatic products for different industries, aquaculture is presented as the solution to the high demand of aquatic products exerted by the world-wide increasing human population. But intensive aquaculture production needs to face different challenges to fulfill the demand increase in a context of sustainability, and covering the requirements of the “OneHealth”, “Green Deal” and “Zero Waste” concepts. Two of the barriers that must be overcome are, i) the necessity of new ingredients in order to replace fishmeal and fish oil in the aquafeeds to decrease the high pressure and environmental impact of the fisheries and avoiding negative effects on fish health. ii) the impact on the health due to emergent pathogens and thermal-stress. Climate change is inducing an increase of infections by the genus Vibrio, an opportunistic group of bacteria that can cause economic losses by mortality or affecting the health of our individuals, and therefore, their animal welfare. The control of infectious diseases is necessary through prophylactic strategies to avoid the use of antibiotics in aquaculture and immunonutrition is one of the prophylactic tools available. Processing animal proteins (PAPs) are among the different ingredients available for aquafeeds, but also the insect meals (IM) and the single cell proteins (SCP) are nowadays promising ingredients for aquafeeds, not only by their nutritional values, but also because of their immunonutritional properties. Therefore, this study aims to evaluate the use of PAPs or the combined use of insect meal and SCP in aquafeeds on fish growth and disease resistance in European sea bass (Dicentrarchus labrax). For this purpose, five experimental diets with two levels of fishmeal replacement (50 or 100%) by either PAPs or insect + SCP were tested for 12 weeks to evaluate growth performance, and the resistance to Vibrio anguillarum infection in sea bass juveniles. Overall, the results show that the diets did not compromise growth performance, except the diet with total replacement of FM by IM and SCP, that also is the diet that compromises survival after Vibrio infection.