Ameliorating effects of dietary mixture of Withania somnifera root extract and vitamin C in Labeo rohita against low pH and waterborne iron stresses

Abstract

The present study was conducted to elucidate the possible effect of a combination of Withania somnifera (Ashwagandha) root extract and dietary l-ascorbic acid (vitamin C) on the immune responses and survivability in Labeo rohita fingerlings against low pH and waterborne iron toxicity. Four diets were prepared containing 0% (control), 0.01% (T1), 0.1% (T2) and 1.0% (T3) of a combination of Withania somnifera (Ashwagandha) root extract and dietary l-ascorbic acid (vitamin C) at the rate of 1:1 (w/w). Fishes were fed for 60 days to find out the best dose and duration of feeding by examining different haematological (haemoglobin, haematocrit, total RBC count, total WBC count, MCV, MCH and MCHC), immunological (NBT, lysozyme and total immunoglobulin activity) and biochemical (glucose, total protein, ALP, SGPT and SGOT level) parameters on 7, 15, 30 and 60 days of feeding. The best response was observed in fish fed with diet T3 within 15 days. The result showed a significant (p < 0.05) increase in haemoglobin, haematocrit, total RBC count, total WBC count, NBT, lysozyme activity, total immunoglobulin and total protein whereas a significant (p < 0.05) decrease in glucose, ALP, SGPT and SGOT level compared to control. Challenged study against waterborne iron (6.02 mg l−1) and low pH (4.2–4.5) after feeding the fish for 15 days with diet T3 showed significantly (P < 0.05) higher protection than control. The study concludes that inclusion of 1.0% Withania somnifera (Ashwagandha) root extract and dietary l-ascorbic acid (vitamin C) combination in diet have a stimulatory effect on immune response and reduces the effect of multiple stresses (i.e., low pH and waterborne iron toxicity) in L. rohita fingerlings.