RESUMEN
The effect of dietary incorporation of soy protein concentrate (SPC) and the concomitant supplementation with taurine on hepatic intermediary metabolism and antioxidant status of totoaba (Totoaba macdonaldi) juveniles was assessed. Four isoproteic and isolipidic diets were formulated containing either 30 or 60% of SPC (diets SP30 and SP60), supplemented or not with 1% of taurine (diets SP30T and SP60T). A fish meal (FM) based diet, without SPC and taurine supplementation, was used as a control. Triplicate groups of 32 totoaba juveniles (average body mass=7.5g) were fed these diets over 45days. Results revealed that dietary FM replacement by SPC depressed the overall intermediary metabolism. Activity of key enzymes of amino acid catabolism and gluconeogenesis was significantly reduced and a trend to reduce glycolysis and glucose-6-phosphate dehydrogenase activity was observed. The incorporation of the highest level of SPC also significantly increased hepatic lipid peroxidation and the activity of superoxide dismutase. Concomitant taurine supplementation restored the activity of amino acid catabolic and gluconeogenic enzymes and hexokinase to levels similar of those of the control diet. Taurine supplementation also led to a significant increase of glucose-6-phosphate dehydrogenase and catalase activity, as well as to a significant reduction of liver lipid peroxidation. These results suggest that taurine may play an important metabolic modulation action on totoaba fed SPC based diets, contributing to the enhancement of the overall metabolism and to the reduction of liver oxidative damage.