BMPR-1 B and GDF9 genes are well known due to their important effects on litter size and mechanisms controlling ovulation rate in sheep. In the present study, polymorphisms of BMPR-1 B gene exon 8 and GDF9 gene exon 1 were detected by single strand conformational polymorphism (SSCP) analysis and DNA sequencing methods in I 00 Mehraban ewe.s. The PCR reaction forced to amplify 140 and 380-bp fragments of BMPR-1 B and GOF9 genes, respectively. Two si ng le nucleotide polymorphis'rns (S NPs) were identified in two different SSCP patterns of BMPR-1 B gene (CC and CA genotypes) that deduced one amino acid exchange. Also, two SNPs were identified in three different SSCP patterns of GDF9 gene (AA, AG and CG genotypes) that deduced one amino acid exchanges. Two dilTerent secondary structures of protein were predicted for BMPR.1 B exon 8, but the secondary protein structures predicted for GDF9 exon 1 were similar together. The evaluation of the associations between the SSCP patterns and the protein structu ne changes with reproduction traits showed that BMPR-1 B exon 8 genotypes have significant effects on some of reproduction traits but the GDF9 genotypes did not have any signific:ant effect The CA genotype of BMPR-1 B CJ\On 8 had a significant positive effect on reproduction performance and could be considered as an important and new mutation, affecting "ihe ewes reproduction performance. Marker assisted selection using BMPR-18 gene could be noticed to improve the reproduction traits in Mehraban sheep.
