Evaluation of Mycoplasma gallisepticuminfection inTabriz broiler breederfarms by RSA

Mycoplasma gallisepticum (MG) is one of the most im portant diseases in Iranian poultry industry and al l over the world. Mortality, poor weight gain and increasing o f feed conversion ratio (FCR) were seen in MG infec ted flocks. In this study, 110 samples were taken from 9 broile r breeder farms located in Tabriz-Iran during 2011- 2012. The prevalence of Mycoplasma gallisepticumwas studied btest, and the clinical signs and lesions were evaluated in all farms.Our results indicated that the prevale nce of MG in Tabriz broiler breeder farms was 19.09 % during study period. Also in farms infected with MG, sever e conjunctivitis, lungs and trachea hyperemia, and sever airsacculitis with caseous exudates were obvious.It can be concluded that MG in broiler breeder farms have potency of great economical losses, and it's clinical signs and gross lesions in infected birds were very seve re and it could decline broiler breeders performance. And also beca use of controlling of MG in Iran the prevalence of MG was lower in comparison to previous years.