Dietary L-Tryptophan potentiates non-specific immunity in Labeo rohita fingerlings reared under elevated temperature

Abstract

At present environmental scenario global climate change is a reality and its affect all living organism includingfish. The aquatic ecosystem is the most affected system as it is the biggest sink for global warming and elevatedtemperature and obviously affects all the aquatic life forms. With this hypothesis an experiment was conductedto evaluate the effect of elevated temperature on Labeo rohita fingerlings and potential of dietaryL-tryptophan(TRP) in mitigating the effects elevated temperature and enhancing the non-specific immunity. Seven hundredand twenty fishes were randomly distributed in three diff erent thermal groups each with three replicates. Thethermal groups were ambient temperature (26 °C), 34 and 38 °C. Then each thermal groups were fed with fourdifferent formulated diets containing 0. 0.36%, 0.72% and 1.44% TRP. The effect of dietary TRP supple-mentation was studied on stress responses, such as cortisol, blood glucose, histopathological changes in liver andkidney and immuno-hematological changes such as red blood cell count (RBC), haemoglobin (Hb), white bloodcell count (WBC), lysozyme, nitroblue tetrazolium (NBT), total serum protein, albumin, globulin and albumin-globulin ratio. Subsequently the treated fish were subjected to challenge test with Aeromonas hydrophila. In thepresent study, primary stress markers were noticeably (p < 0.01) elevated with temperature stress and levelswere reduced with nutritional supplementation of TRP. Similarly, immuno-hematological parameters were al-tered with the exposure of temeparture stress and got improved with dietary TRP supplementation. Results of thepresent study suggest that dietary supplementation of 1.44% tryptophan has definitive role in the mitigation oftemperature stress and gives protection against bacterial infection to L. rohita