Genetic correlations between disease resistance, vaccine-induced side effects and harvest body weight in Atlantic salmon ( Salmo salar )

The objective of this study was to estimate the genetic correlations between vaccine-induced side effects, disease resistance and growth in Atlantic salmon. This was obtained using data from four independent sib groups from each of 144 to 279 families of the same year-class from SalmoBreed AS. Resistance to furunculosis was recorded as survival of unvaccinated (FUR, 279 families) and vaccinated (FUR-V, 150 families) presmolts in two separate challenge tests, while resistance to infectious salmon anemia (ISA) was recorded as survival in a third challenge test with unvaccinated presmolt (ISA, 279 families). Vaccine-induced side effects and growth (body weight at harvest) of vaccinated fish was evaluated on the fourth sample 12months after sea transfer (SW12, 144 families). The genetic correlations of vaccine-induced side effects with resistance to furunculosis (of both vaccinated and unvaccinated fish) and ISA (unvaccinated fish) and with growth were not significantly different from zero. Therefore, selection for one of these traits is not expected to result in large unfavorable correlated response in the other traits. However, a low, albeit significant, unfavorable genetic correlation was found for growth with resistance to furunculosis in vaccinated fish (FUR-V), while that with unvaccinated fish (FUR) was not significantly different from zero. This may indicate that the best responders to vaccination may direct more resources into immunological reactions which, in accordance to resource reallocation theory, may leave fewer resources for growth.