Immune response and disease resistance in Atlantic salmon (Salmo salar L.) fed three levels of dietary vitamin E and the effect of vaccination on the liver status of antioxidant vitamins

Atlantic salmon were fed 40, 300 or 1100 mgall-rac-α-tocopheryl acetate kg feed−1 for 12 weeks.After 6 weeks half of the fish in each group were marked and vaccinated (i.p.injection) against furunculosis and vibriosis. Liver α-tocopherol levelsreflected the dietary input after 6 and 12 weeks of feeding. Noimmunomodulatoryeffects of dietary vitamin E on baseline levels of the immune parameters beforevaccination were detected in this study, as evaluated by antibody dependent andspontaneous plasma complement activities. In general, vaccination increasedplasma complement activities and the number of antigen specific antibodyproducing cells as compared with unvaccinated control fish, but with nodifferences with respect to the vitamin E regimes. Also the ability ofunvaccinated fish to withstand experimental furunculosis was unaffected bydietary vitamin E. The concentrations of α-tocopherol and ascorbic acidinthe liver were, however, negatively affected 6 weeks post vaccination comparedto respective unvaccinated fish.