THE DIETARY TAURINE ADDITION IN FISH FEED; ITS PROTECTIVE ROLE TO THE REACTIVE OXYGEN SPECIES (ROS) PRODUCTION IN THE EUROPEAN SEA BASS (Dicentrachus labrax) DURING A FORCED SWIMMING TEST.
Taurine (Tau) is a neutral β amino acid present in animal tissues and animal by-products, whereas in plants it is scarce. In aquafeed industry, Tau is mainly used as a feed additive to promote growth of marine fish species with limited activity of cysteinesulfinate decarboxylase . Tau supplementation is particularly important in feeds with high percentage of substitution of fishmeal (FM) with alternative protein sources, such as soy products that are often devoid or contain very low concentrations of Tau in comparison to FM. Aside from the promotion of growth, Tau has been found to have other functions. It is an anti-oxidizing agent that favors the protection of cells and tissues from toxic injury, stabilizes the cell membranes, reduces the membrane permeability, and scavenges the reactive oxygen species (ROS) [2;3]. ROS are by-products of normal physiological respiration in the mitochondria. However, disproportionate generation of ROS poses a serious problem to bodily homeostasis as it may cause oxidative stress generated by the imbalance between pro-oxidants and anti-oxidants . Even a moderately intense physical activity, such as sustained swimming, that leads to an increased oxygen demand, can determine an increase of ROS level . Sustained swimming in fish relies on the aerobic metabolism occurring primarily in the well-perfused red muscle in which the mitochondria (the main site of ROS formation) abundance is high [2;5]. Mortelette et al.  highlighted the link between aerobic swimming exercise at the expense of red muscle and ROS production in the eel. Accordingly, the present research aimed to study in European sea bass (Dicentrarchus labrax), the effects of dietary Tau on the swimming performance and the production of ROS during and increasing velocity swimming test, by assessing the critical swimming speed (U crit), the respiratory burst activity (RBA), and the metabolic oxygen consumption (MO 2).