Optimization of dietary pyridoxine improved growth performance, hematological indices, antioxidant capacity, intestinal enzyme activity, non-specific immune response, and liver pyridoxine concentration of fingerling major carp Catla catla (Hamilton)

The current research work was undertaken to evaluate the requirement of fingerling Catla catla (3.7 +/- 0.5 g) for dietary pyridoxine. Triplicate groups of fingerling were fed casein-gelatin based iso-nitrogenous and isocaloric diets (350 g/kg Crude Protein; 16.72 Kj/g Gross Energy) containing eight different levels of pyridoxine (0, 0.5, 1, 2, 4, 6, 8 and 10 mg/kg diet) to satiation for 16 weeks. All the growth parameters were positively affected by increasing concentrations of dietary pyridoxine up to 4 mg/kg diet. Erythrocyte (RBC), hematocrit (Ht), hemoglobin (Hb), alanine (ALT) and aspartate aminotransferase (AST) activities were significantly (P < 0.05) affected and increased up to 4 mg pyridoxine per kg diet. Thiobarbituric acid reactive substances (TBARS) values were found to be highest in fish fed basal diet which decreased with the increase of dietary pyridoxine up to 4 mg/kg whereas, liver superoxide dismutase (SOD) and catalase (CAT) activities increased with incremental levels of dietary pyridoxine up to 4 mg/kg diet. Intestinal protease, amylase and lipase activities significantly (P < 0.05) increased as the amounts of dietary pyridoxine increased up to 4 mg/kg and then leveled off. Fish fed 4 mg/kg pyridoxine reflected significantly higher (P < 0.05) lysozyme, tissue serum protein and alkaline phosphatase activities than fish fed the pyridoxine-deficient diets. However, liver saturation was achieved in fish fed 8 mg pyridoxine per kg diet. Broken-line regression analysis of growth parameters, RNA/DNA ratio, SOD, protease, lysozyme and the liver pyridoxine concentration data against varying levels of dietary pyridoxine indicated the requirement in the range of 3.20-6.87 mg/kg.