The aquaculture sector has been challenged with sustainability issues that are pressing for design of aquafeeds where alternative ingredients (e.g., insect products, by-products of fisheries and animal production, and single-cell biomasses) are being progressively more used in relation to those normally used until now (e.g. fish meal, fish oil, soybean meal). A challenge associated with this transition is ensuring that novel aquafeeds provide all required nutrients, without impairing, and when possible even improving, fish farming performance, from feed conversion to fish nutritional value, and from environmental impacts to fish welfare and health.
H2020 GAIN project is conducting such an assessment of novel formulation concepts for aquafeeds that can drive the aquaculture industry towards using feeds based on circular economy principles and towards zero-waste. This includes evaluation of impact of these novel formulation concepts on fish growth, feed conversion, waste production, nutritional value of fish, fish welfare and health. In this work, we assess three novel aquafeeds formulations against a traditional diet.
Four different diets where tested for gilthead seabream (Sparus aurata) in both a nutritional trial and virtual trials performed using FEEDNETICS: 1) a control diet containing currently used ingredients, including soybean products and low fish meal and fish oil inclusions (CONTROL); 2) a diet rich in processed land animal proteins (PAP); 3) a diet with alternative ingredients without the inclusion of PAP (NPAP); and 4) a diet containing a mixture of alternative ingredients (MIXED) and including also PAP. All formulations were fulfilling the known nutritional requirement of gilthead seabream. This nutritional trial was performed with four replicates, each one with 55 fish with an initial weight of 30 g. Each treatment followed a single-dietary regime (i.e. diets above mentioned), under a temperature of 23±1 ºC, during 9 weeks. The results of virtual and nutritional trials were compared in terms of growth, FCR, fish DHA+EPA contents, and total nitrogen excretion (g N/kg biomass gain). Virtual trials were also conducted until commercial size.
Results show good performances will all diets, but diet CTRL and NOPAP showed superior results in terms of feed conversion ratio, compared to PAP and MIX. Moreover, preliminary results suggest that fish fed with NOPAP diet show a slight improvement of innate immunity. Virtual simulations with these GAIN formulations show some mismatch between modelled and observed values for PAP and MIX, while simulations for CTRL and NOPAP display a good fit. This suggests that our knowledge of nutritional requirements for seabream is incomplete, or one or more of the emerging ingredients have a either a poor amino acid digestibility or contains some anti-nutritional factors. This indicates that novel formulation concepts need to be thoroughly tested.