Antibody response in Atlantic salmon ( Salmo salar) against Vibrio anguillarum and Vibrio salmonicida O-antigens: Heritabilities, genetic correlations and correlations with survival

Genetic variation in antibody response to Vibrio anguillarum and V. salmonicida O-antigens was analysed in serum samples from Atlantic salmon ( Salmo salar) immunised twice with V. salmonicida. Antibody production against V. anguillarum was expected as a response to naturally occurring bacteria in the environment. The material consisted of 1200 fish from 57 full-sib groups within 20 paternal half-sib groups and serum was sampled three times. The estimated heritabilities for antibody concentration at different samplings ranged from 0.0–0.10 with standard errors from 0.03 to 0.21. Variance estimates for common' full-sib effects due to factors other than additive gene effects were low (0.1). The genetic correlations between antibody concentration and body weight tended to be negative at the first sampling (prior to immunisation) and positive at the third sampling (6 weeks after second immunisation). The genetic correlations between antibody response to the two antigens were positive at the first sampling and tended to be negative at the third sampling. Survival during commercial rearing in sea water was recorded for full-sibs reared in a field test. The variation in survival of offspring from different sires was significant. There was a significant positive correlation between the mean survival rate of the half-sib groups in the field test and mean antibody concentration against both V. salmonicida and V. anguillarum O-antigens of half-sib groups sampled prior to immunisation.