Selection and improvement of alternative raw materials for rainbow trout (Oncorhynchus mykiss) aquafeeds through a multiparametric screening tool

Aquaculture growth and sustainability mainly rely on the identification and implementation of alternative raw materials to replace fish meal (FM) and fish oil (FO) and/or its major substitute, the soybean meal (SBM). A five-step screening tool has been designed to identify and improve the use of promising alternative raw materials. To validate it, nine raw materials, including the standard reference (the SBM), were sequentially analyzed regarding (i) the total buffer capacity, alkaline protease activity inhibition and soluble protein content, (ii) soluble phosphorus and phenolic compound content, (iii) modification of nutrients bioavailability and presence of anti-nutritional factors after treatment with exogenous enzyme (Rovabio® Phy), (iv) release of nutrients after in vitro digestion, and (v) the palatability of the formulated diet. SBM partial replacement by selected raw material, the Narbonne vetch (Vicia narbonensis) meal (NVM), was evaluated in a 63-day nutritional trial using rainbow trout (Oncorhynchus mykiss) juveniles. One Control (no SBM replacement) and 4 experimental diets with SBM replacement in two levels (33% and 66%), treated or not with exogenous enzyme Rovabio® Phy, were compared. Fish growth performance and amino acid profile in fish fillet was not significantly affected when SBM was replaced by 33% of NVM treated with exogenous enzyme. Altogether, the present screening tool might be a wise strategy to identify promising alternative raw materials for European aquaculture sustainability, reducing the use of animals in experimentation, the SBM dependency from third countries, and its carbon footprint.