Abstract
Eggs of coho salmon (Oncorhynchus kisutch), rainbow trout (O. mykiss), and masu salmon (O. masou) were artificially inseminated and subsequently immersed in a modified Ordal and Anacker's broth culture of Cytophaga psychrophila (107-108CFU/ml) for 30min. The bacterium was recovered from the eggs at the eyed stage with viable cell counts ranging from 105 to 107CFU/g. The fertilized eggs were disinfected with 50ppm povidoneiodine for 15min immediately after experimental infection. However, C. psychrophila was detected by a broth culture method from 60-80 percent of the surface-disinfected eggs. At the eyed stage, the eggs were disinfected again with povidone-iodine at concentrations of 50-1, 000ppm for 15-120min. C. psychrophila was isolated from all of them at densities of 104-107CFU/g. The uninfected control eggs were all negative for the bacterium. It is concluded that the povidone-iodine treatment is ineffective to eliminate C. psychrophila from salmonid eggs.
