A multi-biomarker approach to evaluate the effect of sodium chloride in alleviating the long-term transportation stress of Labeo rohita fingerlings

Abstract

Transportation of fingerlings to a geographically distant culture system is an extremely stressful event that ultimately hinders the success of culture practices in India. Therefore, the present study aims to evaluate the stress mitigatory potency of NaCl during long-term transportation of Labeo rohita fingerlings based on biochemical profiles, hydromineral characteristic, and hepatic HSP70 mRNA expression. Simulated transportation of L. rohita fingerlings were carried out for 12 h in four treatments of NaCl solution (0.2, 0.4, 0.6 and 0.8% NaCl) along with in non-supplemented control group in triplicate. Serum and tissue sampling were carried out before the transportation (0 h, 1st day), immediately after transportation (12 h, 2nd day), on 3rd day (36 h) and 7th day (168 h) post transportation. Integrated biomarker response (IBR) index is calculated for selected biomarkers such as cortisol, serum glutamic pyruvic transaminase (SGPT), triglyceride, creatinine in serum and lactate dehydrogenase (LDH), malate dehydrogenase (MDH), G-6 phosphatase in tissues at each treatment and control. The result showed a significant change in the level of the stress hormone cortisol, serum ionic concentration, enzymes (SGPT, LDH, MDH), and metabolites (triglyceride, creatinine) along with an upregulation in liver HSP70 mRNA expression. The level of total ammonia?nitrogen was found to be significantly (p < 0.05) higher in control (T0) fishes in comparison to treatments after transportation. IBR index reveals that 0.4% NaCl exhibited the lowest multi-biomarker stress response compared to other treatments and control. Further, a significantly highest survivability was observed in 0.4% NaCl on 7th day post-transportation. Therefore, using of 0.4% salt as a water additive will provide a solution to transportation induced stress problems in L. rohita fingerling and underwrite the success and progress of grow-out fish culture in days to come.