Effect of dietary niacin on growth and body composition of two Indian major carps rohu, Labeo rohita, and mrigal, Cirrhinus mrigala (Hamilton), fingerlings based on dose–response study

摘要

An 15 week two set of feeding experiments were conducted to determine the dietary niacin requirement of Indian major carp fingerlings Labeo rohita and Cirrhinus mrigala, using casein gelatin–based diet. In both experiments, six isonitrogenous (40%) and isoenergetic (15.35 kJ g-1) test diet, with graded levels of niacin (0–50 mg kg-1 dry diet) in gradation of 10 mg kg-1 dry diet, were formulated. In first experiment, fingerling of L. rohita (4.20 ± 1.22 cm; 0.632 ± 0.67 gm) were randomly stocked,in triplicate groups, in 55-L indoor polyvinyl flow-through system (1.5 L min-1) and fed experimental diet at 0800 and 1600 h. Maximum live weight gain (1214%), feed conversion ratio (1.55) and protein efficiency ratio (1.60) were recorded at 30 mg dietary niacin diet. In second experiment, C. mrigala (4.50 ± 1.25 cm, 0.665 ± 0.88) were stocked in same setup. At the end of experiments, maximum live weight gain (1248%), FCR (1.47) and PER (1.70) occurred at 30 mg dietary niacin diet. However, the weight gain, FCR and PER data were analyzed by polynomial regression analysis indicating the requirement of niacin for L. rohita at 36.69, 33.06 and 32.0 mg kg-1, respectively, and for C. mrigala at 35.19, 28.69 and 27.70 mg kg-1 of dry diet, respectively. Whole body composition also showed significant (P < 0.05) differences among each other. On the basis of regression analysis of growth data, it is recommended that the diet for fingerlings should contain niacin at 33 and 30 mg kg-1 dry diet for L. rohita and C. mrigala, respectively.