Effects of dietary cyanocobalamin on growth performance, non‐specific immune response, antioxidant capacity, haematological parameters, body composition and liver cyanocobalamin concentration of fingerling major carp, <i>Catla catla</i> (Hamilton)
Younis Mohd Khan, Mukhtar A. Khan
Abstract
The dietary cyanocobalamin requirement of fingerling Catla catla (3.2 ± 0.13g; 7.2 ± 0.23 cm) was evaluated by feeding casein–gelatin-based isonitrogenous (350 g/kg crude protein) and isocaloric (16.72 kJ/g GE) diets. Triplicate groups of fish were fed diets containing different concentrations of cyanocobalamin (0, 0.01, 0.02, 0.04, 0.08, 0.16 and 0.32 mg/kg) to apparent satiation at 07:00, 12:00 and 17:30 hr for 16 weeks. Maximum absolute weight gain (AWG; 28.9 g/fish), specific growth rate (SGR; 2.01%), best feed conversion ratio (FCR; 1.57), protein retention efficiency (PRE; 30.8%) and highest protein gain (PG; 4.8 g/fish) were recorded in fish fed diet containing 0.04 mg cyanocobalamin per kg. Whole body protein and haematological parameters increased significantly (p < .05) as dietary cyanocobalamin levels increased from 0 to 0.04 mg/kg, and thereafter remained unaffected with further inclusion of cyanocobalamin. Antioxidant and immune parameters increased with increasing concentration of dietary cyanocobalamin up to 0.04 mg/kg diet. Liver cyanocobalamin concentrations increased linearly (p < .05) with the incremental levels of dietary cyanocobalamin. Based on broken-line regression analysis of AWG, PRE, SOD, ALP and TSP activities of fingerling C. catla, the dietary cyanocobalamin requirement ranging between 0.034 and 0.037 mg cyanocobalamin per kg diet is recommended.