RÉSUMÉ
To determine frequency of FMDV carriers in slaughtered cattle at Zyaran abattoir. Cross-sectional study. Three hundred and one tonsils of clinically normal cattle. All of tonsils were tested for determination of FMDV genome using RT-PCR. Then, 30 samples were cultured on MDBK. 20 samples had positive findings in RT-PCR test. Based on sex, age and breed of cattle, RT-PCR results compared with Chi-square and Fisher's Exact Test. McNemar test was used for comparing of virus culture results with RT-PCR. Ninety nine samples were positive in RT-PCR. Relative frequency of FMDV genome presence in tonsils of clinically normal cattle had a significant difference based on sex and breed. The Sistani and Holstein bred had the highest and the lowest relative frequency, respectively samples on cell serotype O of culture were FmDV. One positive sample [Asia 1] Two positive sample[Asia1] was shown by ELISA. Total relative frequency of positive FMDV genome [32.9%] indicates the extensive exposure to FMDV. Breed variation among Sistani cattle [as a variety of Bos indicus] and other bred should be studied in a controlled condition