A. Ciji

Effects of dietary pyridoxine on haemato-immunological responses of Labeo rohita fingerlings reared at higher water temperature

A sixty-day feeding trial was carried out to elucidate the effect of dietary pyridoxine (PN) on hemato-immunological parameters in Labeo rohita fingerlings exposed to an elevated temperature (ET) of 33 °C. Two hundred and seventy fingerlings (6.71 ± 0.32 g) were randomly distributed into six treatments in triplicates (15 fish/tank). Five iso-nitrogenous (356.3 ± 2.7 g/kg crude protein) purified diets were prepared with graded levels (0, 10, 50, 100 and 200 mg/kg diet) of PN. Six treatment groups were P10T26 (10 mg PN + ambient temperature (26 °C), P0T33 (0 mg PN + ET), P10T33 (10 mg PN + ET), P50T33 (50 mg PN + ET), P100T33 (100 mg PN + ET) and P200T33 (200 mg PN + ET). The responses of L. rohita fingerlings to dietary PN were assessed in terms of growth and by analysing some hemato-immunological parameters. When PN supplementation increased from 10 to 200 mg/kg diet, a significant improvement in weight gain percentage was observed. Erythrocyte (RBC) count, leucocyte (WBC) count, haemoglobin content and respiratory burst activity were significantly (p < 0.05) higher in 100 mg PN/kg diet-fed group than their non-PN-fed counterpart. Also, serum albumin, globulin and lysozyme activity were found significantly (p < 0.05) higher in PN-fed groups. The overall results indicated that dietary PN supplementation at 100 mg/kg diet may reverse the negative effects caused by ET and may protect the haemato-immunological status of L. rohita fingerlings reared at higher water temperature.

Physiological changes in Labeo rohita during nitrite exposure: Detoxification through dietary vitamin E

This study investigated the effect of sub-lethal nitrite-nitrogen exposure on Labeo rohita. Fishes fed with different levels of vitamin E (VE) for 60days were exposed to nitrite for another 45days with same feeding regime. There were four treatment groups, viz., VE100-N, VE100+N, VE150+N and VE300+N. After 45days of exposure, lowest specific growth rate was observed in VE100+N and highest in VE100-N. Reno-somatic index and methaemoglobin reductase activity were significantly increased by nitrite exposure. Highest Hb and Hct were observed in VE100-N and significantly decreased upon nitrite exposure. Significant differences were observed in the activities of catalase and SOD as well as serum potassium and chloride levels among different treatments. However, serum calcium and osmolality was not significantly varied. Nitrite exposure caused marked increase in nitrite concentration in gill, liver and muscle. In liver and muscle dietary supplementation of higher amounts of VE found to reduce nitrite accumulation. It was noticed that nitrite exposure has adversely affected growth, haematological variables, ionic balance and dietary supplementation with additional amounts of VE found to overcome the adverse effects of nitrite-nitrogen. Detoxification of nitrite by methaemoglobin reductase system was enhanced by dietary supplementation of additional amounts of VE.