Abstract: Subclinical mastitis were detected from 1020 milk samples collected from 8 dairy farms of Xinjiang by the method of LMT and Escherichia coli were isolated and identified from positive samples. Immune serums were prepared with 8 Escherichia coli chosen from the strains isolated from different farm. Common antigens were screened from other 21 Escherichia coli isolated from subclinical mastitis with tube agglutination test. Result showed that immune serum titer was 1∶2560 to 1∶5120 and 85.7% strain tested give positive reaction with 3 immune serum. SDS-PAGE analysis of 8 strains which used for immune serum made demonstrated that some similar or common protein bands appeared in 20 to 84 ku. Western blotting of 8 strains with immune serum shows that reaction occurred in 70 ku. The result shows that Escherichia coli isolated from subclinical mastitis samples have common antigens.

Key words: dairy cow mastitis; E. coli; common antigens