Abstract: The objective of the present study was to observe the distribution of the serotypes and pathogenicity to mice of Salmonella isolated from dairy cattles with mastitis or endometritis. Salmonella strains were isolated by selective medium. The serotype of the isolates were determined by A to F polyvalent and O and H monovalent diagnostic serum agglutination test；Mice infection model was induced by intraperitoneal injecting of the Salmonella isolates. The morbidity and mortality of the mice were observed. Tissue lesions were also observed by using tissue sectioning. A total of 38 of Salmonella strains were isolated and identified from 460 samples of bovine mastitis or endometritis, the isolating rate of pathogenic Salmonella was 8.3%. 38 strains all belonged to A to F group, and 8 groups and 14 serotypes were observed. S.typhimurium （39.5%）was the most commonly isolated Salmonella. Mortality of five selected strains ranged from 50% to 80% respectively. Meanwhile, Salmonella strains were recovered from each experimental mouse’s hearts and livers. There were necrosis in heart, liver and kidney of mice. Bacterial embolus was observed in lung of infected mice. Salmonella isolated from dairy cattles had complex serotypes and were strongly pathogentic to mice, but there were differences in pathogenicity of different Salmonella isolates.

Key words:

dairy cattles; Salmonella; serotype; mice; pathogenicity