Influence of dietary vitamin C and bovine lactoferrin on blood chemistry and non-specific immune responses of Japanese eel, Anguilla japonica

A trial was conducted to determine the effect of ascorbyl-2-monophosphate Na/Ca (AMP-Na/Ca) and bovine lactoferrin (Lo on blood chemistry and non-specific immune response of Japanese eel juveniles. Test diets with 32 or 762 mg AsA/kg diet, and with or without 500 mg Lf/kg diet were fed to juvenile Japanese eels (75.5 +/- 4.4 g) once a day for 3 weeks. A diet without AMP-Na/Ca and Lf supplements was employed simultaneously as a negative control. Liver AsA content of fish fed diets containing 762 mg AsA/kg was significantly (P<0.05) higher than fish fed diets containing 32 mg AsA/kg regardless of Lf level. Fish fed diets containing 762 me AsA/kg showed lower serum glutamic oxaloacetic transaminase (GOT), lactate dehydrogenase (LDH), and serum total bilirubin (T-Bil) than fish fed diets containing 32 mg AsA/kg and the negative control group (P<0.05), respectively. Lf was not a significarit factor on those parameters. Fish fed diets containing 762 mg AsA/kg showed significantly higher lysozyme activity (LA) of mucus and serum, and bactericidal activity of mucus than the fish fed the diet containing 32 mg AsA/kg. Lf was a significant factor on serum LA, and there was an interaction between AsA and Lf on serum bactericidal activity. These results demonstrated that AMP-Na/Ca is an effective AsA source and higher level in the diet improved blood chemistry and non-specific immune function of Japanese eel. Moreover, the highest serum LA and mucus bactericidal activity were found in eel fed the diet containing the highest AsA content with supplemental Lf. (C) 2007 Elsevier B.V. All rights reserved.