Dietary pyridoxine requirement of the Indian catfish, Heteropneustes fossilis

Indian catfish were fed semi-purified diets containing 0, 1.7, 3.4, 6.5, 13 .5 and 27.2 mg/kg of pyridoxine for 15 weeks. The highest weight gain was f or fish fed the diet supplemented with 3.4 mg pyridoxine/kg, followed by fi sh fed the diets with 6.5, 27.2, 13.5 and 1.7 mg pyridoxine/kg, and the low est in fish fed the unsupplemented control diet. Patterns of feed efficienc y ratio (FER) and protein efficiency ratio (PER) were similar to those of t he weight gain. Survival of fish fed the control and pyridoxine-supplemente d diets were 45% and 80% to 100%, respectively. Pyridoxine deficiency signs such as anorexia, lethargy, pale body colour, tetany, convulsions and haem orrhages in intestine and kidney were observed in fish fed the pyridoxine-f ree diet. Anaemia in pyridoxine deficient fish was characterized by pale li vers, spleens and gills. Fish fed 3.4 mg pyridoxine/kg, showed higher eryth rocyte number (RBC), haemoglobin (Hb) and haematocrit (Ht) and lower mean c arpuscular volume (MCV) than those fish fed the other diets. The maximum li ver pyridoxine content and alanine aminotransferase (AAT) activity were obs erved in fish fed the 3.4 mg pyridoxine/kg diet. The associated liver pyrid oxine content and AAT activity for maximum growth ranged from 3.24 to 4.65 mug/g tissue and 2.45 to 3.50 mol pyruvate x 10(6)/mg liver.h, respectively . Broken-line regression analysis showed that the optimum dietary pyridoxin e requirement for maximum growth of Heteropneustes fossilis under these exp erimental conditions was 3.21 mg/kg diet. (C) 2001 Elsevier Science B.V. Al l rights reserved.