Evaluation of the Effects of the Enriched-Organic Diets Composition on European Sea Bass Welfare through a Multi-Parametric Approach

Pierluigi Carbonara,Walter Zupa,Sébastien Alfonso,Mariano Dara,Matteo Cammarata,Isabella Bitetto

doi:10.3390/jmse8110934

Pierluigi Carbonara, Walter Zupa + Show 4 more

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https://doi.org/10.3390/jmse8110934

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Abstract

Three groups of European sea bass (Dicentrarchus labrax) were fed for seven months, with either a conventional diet or two different organic diets, which contain organic vegetables and a natural antioxidant compound. The two organic diets differed themselves in terms of raw proteins, fish oil, and lipid contents. Sea bass welfare condition was assessed in relation to these three diets, using 16 different indicators. These were: swimming activity (recovery test, muscle activity), haematological and serological stress indicators (haematocrit, haemoglobin, red-blood-cell count, cortisol, glucose, lactate), aspecific immunity parameter (lysozyme), indicators of exposure to organic contaminants (7-ethoxyresorufin-O-deethylase and glutathione-S-transferase), and growth parameters (weight gain, specific growth rate, feed conversion ratio, protein efficiency ratio, and hepato-somatic index). Most of these parameters individually did not give consistent responses, but their integration can provide an accurate evaluation of the fish welfare conditions among the three diet experimental groups. The multiparametric approach outlined a comprehensive picture of sea bass physiological state. The principal component analysis and the multi-criteria-decision-analysis were found to be useful tools for an integrated fish welfare assessment, highlighting that the best welfare condition was achieved in the experimental group fed with the protein-rich organic diet.

Highlights

Aquaculture plays a crucial role for supplying the increasing demand of animal protein to feed the growing world population [1]
Fishmeal and fish oil derived from the wild can be considered a vehicle of contamination as organochlorines, such as polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAH), and dioxins, principally accumulate in the lipidic fraction [2]
The haematocrit values decreased over the experimental period in all treatments, reaching levels significantly lower than those found at the beginning of the experiment (ANOVA, p < 0.05)

Summary

Introduction

Aquaculture plays a crucial role for supplying the increasing demand of animal protein to feed the growing world population [1]. The capacity of wild fisheries to cope with the increasing demand for fishmeal and fish oil has reached the limit of sustainability [1]. Fishmeal and fish oil derived from the wild can be considered a vehicle of contamination as organochlorines, such as polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAH), and dioxins, principally accumulate in the lipidic fraction [2]. These contaminants are attracting particular attention since exposure through diet can trigger a long-lasting effect on fish physiology, behaviour, and growth and reproduction [3]. Aquaculture tends to move toward more sustainable and organic sources of fish meal and oil [4,5], even if the challenge of the transition is still huge [6]

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