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. sa lmonicida O-antigens was analysed in serum samples from Atlantic salmo n (Salmo salar) immunised twice with V. salmonicida. Antibody producti on against V. anguillarum was expected as a response to naturally occu rring 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 con centration at different samplings ranged from 0.0-0.10 with standard e rrors from 0.03 to 0.21. Variance estimates for common full-sib effect s due to factors other than additive gene effects were low (0.1). The genetic correlations between antibody concentration and body weight te nded to be negative at the first sampling (prior to immunisation) and positive at the third sampling (6 weeks after second immunisation). Th e genetic correlations between antibody response to the two antigens w ere positive at the first sampling and tended to be negative at the th ird sampling. Survival during commercial rearing in sea water was reco rded for full-sibs reared in a field test. The variation in survival o f offspring from different sires was significant. There was a signific ant positive correlation between the mean survival rate of the half-si b groups in the field test and mean antibody concentration against bot h V. salmonicida and V. anguillarum O-antigens of half-sib groups samp led prior to immunisation.