Calf no. | Pathological changesa | E. coli serotypeb | Positive samples | MLD50 for E. coli (CFU)c |
---|
1 | severe | O8 | intestine, rectal swabs | 5.45 × 109 |
2 | moderate | O8 | intestine | ND d |
3 | severe | O8 | intestine, rectal swabs | ND |
4 | severe | O8 | intestine, rectal swabs | ND |
5 | mild | O8 | intestine | ND |
- a The pathological changes of intestines from affected calves were estimated by visual examination.
- b The serotypes of each strains were determined by agglutination test with 25 prevalent antiserums of pathogenic E. coli.
- c MLD50 were determined by intraperitoneally inoculating six mice in each group with 50 μl of serial 10-fold dilutions E. coli and calculated by the method of Hamilton et al. [20].
- d ND indicates that the LD50 of these strains was not determined.