Dietary thiamin and pyridoxine requirements of fingerling Indian major carp,Cirrhinus mrigala(Hamilton)

Abstract

Two experiments were conducted to quantify the dietary thiamin (experiment I) and pyridoxine (experiment II) requirements of fingerling Cirrhinus mrigala for 16 weeks. In experiment I, dietary thiamin requirement was determined by feeding seven casein–gelatin-based diets (400 g kg−1 CP; 18.69 kJ g−1 GE) with graded levels of thiamin (0, 0.5, 1, 2, 4, 8 and 16 mg kg−1 diet) to triplicate groups of fish (6.15 ± 0.37 cm; 1.89 ± 0.12 g). Fish fed diet with 2 mg kg−1 thiamin had highest specific growth rate (SGR), protein retention (PR), RNA/DNA ratio, haemoglobin (Hb), haematocrit (Hct), RBCs and best feed conversion ratio (FCR). However, highest liver thiamin concentration was recorded in fish fed 4 mg thiamin kg−1 diet. Broken-line analysis of SGR, PR and liver thiamin concentrations exhibited the thiamin requirement in the range of 1.79–3.34 mg kg−1 diet (0.096–0.179 μg thiamin kJ−1 gross energy). In experiment II, six casein–gelatin-based diets (400 g kg−1 CP; 18.69 kJ g−1 GE) containing graded levels of pyridoxine (0, 2, 4, 6, 8 and 10 mg kg−1 diet) were fed to triplicate groups of fish (6.35 ± 0.37 cm; 1.97 ± 0.12 g). Fish fed diet containing 6 mg kg−1 pyridoxine showed best SGR, FCR, PR, RNA/DNA ratio, Hb, Hct and RBCs, whereas maximum liver pyridoxine concentration was recorded in fish fed 8 mg kg−1 dietary pyridoxine. Broken-line analysis of SGR, PR and liver pyridoxine concentrations reflected the pyridoxine requirement from 5.63 to 8.61 mg kg−1 diet. Data generated during this study would be useful in formulating thiamin- and pyridoxine-balanced feeds for the intensive culture of this fish.