RESUMEN
The Holstein bulls [n=50] were genotyped for bovine lymphocyte antigen [BoLA-DRB3.2] alleles by polymerase chain reaction and restriction fragment length polymorphism [PCRRFLP]. Genomic DNA was extracted from bull semen using phenol-chloroform method. A two-step PCR was conducted in order to amplify a 284 base-pair fragment of the target gene. Amplicons were digested by RsaI, HaeIII and BstyI restriction endonuclease enzymes. Digested fragments were electrophoresed on 8% polyacrylamide gel and visualized after silver staining. Seventeen BoLA-DRB3.2 alleles were identified with frequencies ranging from 1 to 21%. Sixteen alleles were similar to those reported previously and one was a new allele which has not been reported before. The frequencies of alleles BoLA-DRB3.2 *3, *8, *10, *11, *12, *13, *15, *16, *21, *22, *23, *24, *28, *51, *iaa, *ibb, *qbb were 2, 9, 2, 14, 1, 2, 4, 10, 1, 14, 5, 21, 6, 6, 1, 1, and 1%, respectively. The seven most frequent alleles [BoLA-DRB3.2 *8, *11, *16, *22, *24, *28, *51] accounted for 80% of alleles in the investigated population. This data indicate that the BoLADRB3.2 locus is highly polymorphic in Holstein bulls of Iran