Effects of feeding regime on susceptibility of Atlantic salmon (Salmo salar) to cold water vibriosis

Sammendrag

We have investigated appetite and survival of Atlantic salmon (Salmo salar) given different feeding regimes after an experimental infection with Vibrio salmonicida, causing cold water vibriosis. Six tanks were challenged with the bacteria, while three tanks served as controls. After the infection, two of the infected tanks and one control tank were given an optimal feeding regime, three corresponding tanks were given a restricted feeding regime and three tanks were not fed. Feed intakes were monitored using X-radiography 1 week before and once a week during 4 weeks after infection. The study revealed that feeding regimes strongly affected survival of the infected fish. In the groups with optimal feeding, 64.4% of the fish survived, while in the groups with restricted feeding 42.5% of the fish survived, and in the starved groups 98.8% of the fish survived. In the control groups, 99.8% of the fish survived. There were transient reductions in feed intake (40–50%) of infected fish fed optimally 2 and 3 weeks after infection, relative to the uninfected control group. Four weeks after infection, there were no differences in feed intake between infected and control fish. Growth of infected fish fed optimally was significantly lower 3 and 4 weeks after infection, compared to fish in the control groups.