Effects of different levels of dietary cyanocobalamin on growth, liver cyanocobalamin concentration, antioxidant capacity, intestinal enzymes and non-specific immune response for optimum inclusion in the commercial feeds of fingerling Channa punctatus (Bloch)

Abstract

For increasing the aquaculture production, it is crucial to develop quality feeds with all the essential nutrients including vitamins. Since vitamins are essential nutrient required in small amount to perform structural and functional roles, information on the dietary vitamin requirements is essential. This study was conducted to investigate the effects of varying levels of dietary cyanocobalamin on growth, liver cyanocobalamin concentration, antioxidant capacity, intestinal enzymes and non-specific immune response and optimize dietary requirement for developing feeds for intensive culture of fingerling Channa punctatus. Seven purified diets (450 g/kg CP, 18.71 kJ/g GE) with 0, 0.02, 0.04, 0.08, 0.16, 0.32 and 0.64 mg/kg of cyanocobalamin were fed to fish (4.27 ± 0.18 g) until satiation for 12-week. Maximum live weight gain (845%), protein efficiency ratio (1.50), best feed conversion ratio (1.48), protein deposition (25.98%) and protein gain (6.24 g/fish) were recorded in fish fed 0.08 mg cyanocobalamin per kg diet. Hematocrit, red blood cells, hemoglobin, mean cell volume and mean cell hemoglobin enhanced significantly with the increase of cyanocobalamin up to 0.08 mg/kg diet and then leveled off. However, intestinal protease, amylase and lipase activities increased (P < .05) as the amounts of dietary cyanocobalamin increased up to 0.16 mg/kg. Dietary cyanocobalamin levels significantly (P < .05) affected liver glutathione peroxidase, superoxide dismutase, catalase, total serum protein, lysozyme and alkaline phosphatase activities which were found to be highest in fish fed 0.16 mg cyanocobalamin per kg diet. Liver cyanocobalamin concentrations increased linearly (P < .05) with the incremental doses of dietary cyanocobalamin. However, biometric indices including HSI and VSI all showed little difference (P < .05) among all the treatments while CF exhibited upward trend up to 0.08 mg/kg dietary cyanocobalamin. Live weight gain, feed conversion ratio, protein deposition, hematocrit, hemoglobin, superoxide dismutase, catalase, glutathione peroxidase, alkaline phosphatase, protease and lipase activities were regressed against increasing concentrations of dietary cyanocobalamin using broken-line model which yielded the requirement in the range of 0.067–0.15 mg/kg diet. The information generated in this feeding trial will enable feed manufacturers to develop cyanocobalamin-balanced feeds for intensive culture of C. punctatus.