THE EFFECT OF VITAMIN-E ON THE IMMUNE-RESPONSE OF THE ATLANTIC SALMON (SALMO-SALAR L)

Atlantic salmon parr were maintained on diets of depleted (7 mg vitamin E/kg), intermediate (86 mg vitamin E/kg), commercial (326 mg vitamin E/kg) and high (800 mg vitamin E/kg) vitamin E levels. After 20 weeks, group comparisons of plasma and liver vitamin E concentrations, serum protein levels, total and differential leucocyte counts and haematocrits were made. Nonspecific defences were examined and included respiratory burst (superoxide anion) activity, serum lysozyme levels, and serum complement activity. Specific humoral responses for each group were also assessed following immunisation with A. salmonicida or human gamma globulin, as was lymphokine (MAF) production by head kidney leucocytes in response to stimulation by Con A and PMA. Fish fed commercial and vitamin E depleted diets were exposed to a virulent strain of A. salmonicida and mortalities were recorded over a 28-day period. Fish on vitamin E depleted diets had a significantly increased mortality rate compared to fish on the commercial diet. However, only complement activity was compromised in these vitamin E depleted fish, as determined by the ability of their serum to opsonize bacteria and cause haemolysis of antibody-coated sheep red blood cells. © 1990.