Prevalence of Mycoplasmopsis bovis and Histophilus somni in Raw Bovine Semen from Artificial Insemination Collection Centers in the United States

Mycoplasmopsis bovis and Histophilus somni are important bovine bacterial pathogens. M. bovis causes mastitis and bovine respiratory disease (BRD) and is linked to reduced fertility and abortion. H. somni is implicated in BRD, arthritis and myocarditis. Currently, under the guidance of Certified Semen Services (CSS), semen used for artificial insemination (AI) is treated with Gentamicin, Tylosin, Lincomycin, and Spectinomycin (GTLS) during the semen extension process to control and prevent the transmission of various bacterial species including M. bovis and H. somni. GTLS has been shown to only exhibit a bacteriostatic effect on M. bovis and therefore understanding the prevalence of M. bovis is of interest, especially as evidence has demonstrated that M. bovis can be spread through contaminated extended semen used for AI. This led to a nationwide survey sampling untreated, raw bovine semen from various CSS-certified AI facilities. Raw semen was tested to determine the prevalence of M. bovis and H. somni. Culture based methods were used to evaluate semen for both organisms and polymerase chain reaction was additionally used to evaluate for M. bovis. Of 278 semen samples, no M. bovis was detected using PCR or culture leading to a ≤ 0.9% likelihood of M. bovis being shed into semen at CSS-approved AI facilities. However, high H. somni carriage rates (>86%) were observed. These findings indicate that facilities have limited likelihood to transmit M. bovis in semen. H. somni should be re-evaluated as a pathogen of interest to the AI industry as these data indicate a high carriage rate.