摘要：Haemophilus somnus is a small, pleomorphic, gram-negative and coccobacillusbacterium that has been identified as a common inhabitant of the sheath in bulls and the vagina and major vestibular gland in cows. The purpose of this study was to determine the frequency of H. somnus infection in the semen samples of bullsin Iran. H. somnus was isolated from 40 of 185 (21.62%) bull's semen. Results showed high frequency of H. somnus infection in artificially prepared semen that is used for artificial insemination. The findings of this study indicate that semen samples of bulls that are used for artificial insemination are important sources ofH. somnus infection in Iran. In addition, it can be concluded that this bacteriummay normal flora of the bovine prepuce and that dissemination from the male bovine reproductive tract and it can be related to H. somnus -associated diseases.To control and prevention of the distribution of H. somnus, examination of bull's semen for artificial insemination seems to be necessary.
