Submitted to: North American Journal of Aquaculture
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/20/2014
Publication Date: 3/18/2014
Citation: Watson, A.M., Barrows, F., Place, A.R. 2014. Effects of graded taurine levels on juvenile cobia. North American Journal of Aquaculture. 76:190-200. Interpretive Summary: Taurine is a compound found in fish and animals, but not in plants. It is considered an essential part of the diet for carnivorous marine fish like cobia, and field observations have suggested that typical fish meal diets do not contain sufficient taurine to maintain the health of the animals. Two studies were conducted with different size cobia to determine if supplementation of taurine to a high fish meal contain diet had any effects. The results of these studies show that with a high fish meal diet taurine supplementation did not affect growth or survival of cobia during the study.
Technical Abstract: Taurine, which has multiple important physiological roles in teleost fish and mammals, is an amino acid not found in alternative protein sources not derived from animals. Although taurine is found in fish-meal-based feeds, its high water solubility leads to lower taurine levels in reduction-process-based feeds, which marine carnivores such as Cobia Rachycentron canadum are adapted to in their natural diets. Graded taurine supplementation (0, 0.5, 1.5, and 5.0%) added to a traditional fish-meal-based formulation was examined in two growth trials with Cobia: one initiated with 10-g individuals and the second initiated with 120-g individuals. During the first trial, in which growth as weight gain ranged from 123 to 139 g per fish, there was an increase in dietary taurine and a decrease in the feed conversion ratio from 1.04 to 0.99. During the second trial, in which growth ranged from 227 to 313 g gained per fish, there was no significant difference in performance characteristics between dietary treatments. Messenger RNA transcript expression levels for two of the genes involved in taurine synthesis, cysteine dioxygenase (CDO) and cysteamine dioxygenase (ADO), as well as the membrane-bound taurine transporter, TauT, were also measured at the conclusion of the second trial. Increasing dietary taurine in a diet containing 34.5% fish meal did not result in significantly different growth or production characteristics in Cobia, but did result in significantly increased taurine levels in fillet, liver, and plasma.