Examination of the immunomodulatory properties and the effect on disease resistance of dietary bovine lactoferrin and vitamin C fed to Atlantic salmon (Salmo salar) for a short-term period

Atlantic salmon were fed commercial diets with or without supplementation o f 140 mg bovine lactoferrin (Lf) kg(-1) feed, and with 150 or 1000 mg vitam in C (ascrobic acid, AA) equivalents kg(-1) feed using AA polyphosphate, in a 22-factorial design for 19 days. Following the dietary treatment the exp erimental fish were challenged with Aeromonas salmonicida ssp. salmonicida or infectious salmon anaemia (ISA) virus. The specific growth rates were un affected by the dietary treatments. Liver AA concentration was increased in all dietary groups demonstrating that the fish had been eating. Liver iron and head kidney catalase did not differ significantly between the groups. Lysozyme activity in serum and head kidney, spontaneous and antibody specif ic serum complement-mediated haemolysis as well as phagocytic chemiluminesc ent responses were all unaffected by the differences in dietary composition . In the furunculosis and ISA challenge experiments there were no significa nt differences in cumulative mortality between the groups. In conclusion, u nder the experimental conditions used in this study we were not able to det ect any effects on non-specific immunity or disease resistance after feedin g Atlantic salmon Lf and/or AA supplemented diets for a short period, but m asking of potential effects due to low water temperature (8.4 degrees C) an d limited feed intake cannot be excluded. (C) 1999 Academic Press.