The influence of ascorbic acid (vitamin C) on non-specific immunity in the turbot (Scophthalmus maximus L.)

The effects of ascorbate supplementation on the non-specific immunologicalstatus in juvenile turbot, Scophthalmus maximus L., was evaluated. A basic diet was supplemented with 300, 1000 and 2000 mg kg −1 of calcium ascorbate and fed to separate groups of fish over a 127 day period. After 70 days, several haematological indices associated with immunocompetence displayed significant changes relating to vitamin C status. Serum lysozyme was markedly enhanced whilst other parameters such as adherent kidney and spleen cell phagocytic capacity showed a positive correlation with dietary vitamin C levels up to 127 days. Differential leucocyte counts, total serum protein and general histology of major organs were not found to be affected by dietary ascorbate levels. In addition, there was no evidence of scorbutic symptoms in turbot receiving the unsupplemented diet.