EFFECTS OF THE ENRICHED-ORGANIC DIETS COMPOSITION ON EUROPEAN SEA BASS (Dicentrarchus labrax) NEW TOOLS FOR FISH WELFARE EVALUATION IN AQUACULTURE

In recent years, concern for the welfare of animals, including fish, has a strong impact on public opinion, putting pressure not only on producers and the scientific community, but also on institution to guarantee adequate "standards” for animal welfare. The market today challenges the production capacity of aquaculture by asking for products with consistently high quality. Unlike other farming methods, there is a lack of scientific information on the welfare of fish reared under intensive aquaculture conditions. Among the various aspects that characterize aquaculture, the increase in fish welfare has an impact on public opinion also for economic reasons whereby is very important to keep animals in good health, determine a higher feed conversion rate, lower mortality, optimal growth rate and high quality of the animal raised. Whereas stress events, acute and chronic, are reflected on the flesh, due to the increase in muscle activity (generally associated with this condition). We have firstly demonstrated that accelerometer tags are useful tools for welfare monitoring, indeed they do not affect welfare and health of implanted fish and that tagged fish can be sampled during experiments and be considered as representative of population, by displaying similar growth and physiological parameters compared to untagged fish. Consequently, the purpose of this study is to investigate the effect of two organic diets (contain organic vegetables and a natural antioxidant compound) on the welfare of the European sea bass compared to one conventional. A holistic approach was adopted, including the measurement of the primary stress response (cortisol), secondary (i.e. lactate, glucose, haematological parameters, lysozyme) and tertiary (i.e. swimming performance, muscle activity and growth parameters) indicators. In parallel, we evaluated the enzymatic activities of 7-ethoxyresoruphine-O-deethylase and glutathione-S-transferase, as index of function of the microsomal hepatic system of mixed function oxygenase (MFO), to evaluate the possible effects of pollutant contamination through the diet. In this study, multiparameter analysis approaches were performed to bring a better understanding of the effectiveness of a holistic approach to quantify welfare in organic aquaculture. The multi-parameter approach has outlined a complete picture of the physiological state of the sea bass. The Principal Component Analysis and the Multi-Criteria-Decision-Analysis have proved to be useful tools for an integrated assessment of the well-being of the fish, highlighting that the best condition was achieved in the experimental group fed with the organic protein-rich diet.