Protective effect of hydroxy-selenomethionine supplementation in the diet of tambaqui (Colossoma macropomum) subjected to transportation stress

Abstract

ABSTRACT Selenium (Se) is an antioxidant mineral and has been included in fish feed formulations in the organic form of hydroxy-selenomethionine (OH-SeMet). This study evaluated how different concentrations of this substance, supplemented in the diet, act on tambaqui (Colossoma macropomum) muscle before and after a stressor (transportation). Juvenile fishes were divided into five treatments receiving 0.0; 0.3; 0.6; 0.9; 1.2 mg kg-1 Se supplementation for 75 days. After that period, the fish were exposed to transportation for four hours. Sampling of muscle tissue for the measurement of biochemical parameters occurred on day 75, prior to transportation, and one week after transportation (day 83). The activity of enzymes superoxide dismutase and glutathione-S-transferase did not change. Supplementation with 1.2 mg kg-1 Se increased the level of reduced glutathione before transportation, and 0.9 and 1.2 mg kg-1 Se reduced the level of thiobarbituric acid reactive substances levels before and after transportation. After transportation, we observed reduced glutathione levels in fish treated with 0.3, 0.6 and 1.2 mg kg-1, reduced ascorbic acid level in fish fed 0.6 mg kg-1 Se, and reduced total protein concentration in fish fed 0.3 mg kg-1 Se, as compared to the levels before transportation. In conclusion, the presence of different concentrations of Se in the fish diet promoted different patterns of response to redox status, minimizing oxidative damage generated by the stressor event.