Fate of four fish pathogens after exposure to fish silage containing fish farm mortalities and conditions for the inactivation of infectious pancreatic necrosis virus

Exposing three bacterial fish pathogens ( Aeromonas salmonicida, Yersinia ruckeri and Renibacterium salmoninarum) to a commercial fish silage caused their rapid destruction. However, it was found that infectious pancreatic necrosis virus survived in silage for long periods at the prevailing ambient temperature in Scotland. Native levels of virus could be inactivated by heating the silage preparation to a temperature of 60°C for 2 h or by the addition of the virucidal agent Virkon to 1 100 w/v dilution. As Divosan Forte only inactivated IPN virus slowly in silage acids, Virkon would be the better terminal disinfectant for silage. The practice of ensiling fish farm wastes to hygienically dispose of infected materials such as mortalities and infected offals is discussed.