Hemato-Immunological Responses of Labeo rohita Juveniles to Temperature and Salinity Stress: Effect of Dietary L-tryptophan

Abstract

In the present investigation, the Labeo rohita juveniles that were previously fed with vitamin E and tryptophan supplemented diet for 60 days were exposed to sub-lethal concentration of nitrite-nitrogen (2.0 mg/l) for the next 45 days with the same feeding regime. After 45 days of nitrite exposure, nitrite was withdrawn and the fishes were again fed with their respective diets for the next 60 days. After this period, the different treatment groups were challenged with Aeromonas hydrophila to study the degree of immunosuppression caused by nitrite and the efficacy of vitamin E and tryptophan in improving the fish health and survival. From the results obtained in the present study, it could be concluded that the enhanced non-specific resistance factors viz., NBT, lysozyme activity, and WBC count observed in the high vitamin E and tryptophan diet fed groups compared with control upon challenge with A. hydrophila clearly revealed the role of these two additives in boosting non-specific immunity in rohu. Moreover, the survival percentage of nitrite induced immunocompromised L. rohita was also improved by feeding elevated amounts of vitamin E and tryptophan in the diet.