Effect of Dietary Vitamin E and Nitrite Exposure on Growth and Metabolic Variables of Labeo rohita Juveniles

Abstract

This study embodied the effect of sub-lethal nitrite exposure on growth and metabolic responses of Labeo rohita juveniles fed elevated levels of vitamin E (VE). Fishes fed with normal and elevated levels of VE for 60 days were exposed to sub-lethal nitrite (2.0 mg L-1) for another 45 days under same feeding regime. There were six treatment groups, viz, VE0-N, VE0?N, VE100-N, VE100?N, VE150?N and VE300?N. Except the groups VE0-N and VE100-N, all other groups were exposed to nitrite. Weight gain percentage was significantly lowest in VE0?N and highest weight gain was observed in VE100-N group. Dietary supplementation of VE augmented weight gain of nitrite exposed L. rohita. Similarly, protein efficiency ratio was lowest and highest in VE0?N and VE100- N respectively. Nitrite exposed groups recorded higher LDH, AST and ALT activities compared to their unexposed counterparts (VE0-N & VE100-N). The highest activities of LDH, AST and ALT were observed in VE0?N. Dietary supplementation with additional levels of VE found to significantly reduce the activities of these enzymes. Nitrite exposure was found to significantly reduce serum total protein, albumin and globulin levels and groups which are fed with additional amounts of VE (150 and 300 mg kg-1 diet) recorded total protein, albumin and globulin values similar to that of the nitrite unexposed groups. It was noticed that nitrite exposure has adversely affected growth, metabolic activity and immunological status of L. rohita and dietary supplementation with additional amounts of VE found to overcome the adverse effect of nitrite exposure.