[Prevalence of Mycoplasmas in commercial layer flocks during laying period].

Within this study's range, laying hens from different housing systems were investigated on prevalence of Mycoplasma sp. for the duration of one laying period, with an emphasis on the two clinically relevant species M. synoviae and M. gallisepticum. Tracheal swabs were analysed for mycoplasms by genus- and species-specific amplification after DNA extraction. Of 919 collected tracheal swabs, 84% were positive for the genus-specific test, while 75% turned out positive for M. synoviae. Mycoplasms were detected at some time during the laying period in all 19 flocks included in this investigation. Using a species-specific PCR, only one flock of a free-range system was free of M. synoviae. On the contrary, PCR analysis did not detect M. gallisepticum in any of the collected samples. Individual and flock examinations revealed no correlation between clinical symptoms and the presence of M. synoviae in hens and flocks, respectively. As the majority of the examined flocks were already positive for M. synoviae upon entry, the establishment of a control regime for Mycoplasma sp. would be advisable for parent stock and rearing facilities.