The BMPR1B gene is one of the major genes controlling litter size in sheep. The SNP OAR6: 29382188A>G (NC_019463.1) is known as the Booroola/FecBB fecundity mutation with additive effect on litter size. In the present work, Iranian Moghani ewes were artificially inseminated with sperm from two strains of homozygous Booroola carrier rams from New Zealand, Merino Tamlet and Romney. As expected for the first generation, F1 crossbred lambs of Booroola Merino × Moghani and Booroola Romney × Moghani were genotyped as heterozygous carriers of the Booroola mutation (FecBB/+ genotype) using restriction fragment length polymorphism (RFLP) analysis. Growth of F1 lambs was followed by regular weighing and measuring from birth to 11 months of age. While birth weight was the same, the growth rate was significantly increased in F1 Booroola Romney × Moghani crossbred lambs compared to Booroola Merino × Moghani lambs after 3 months of age. In contrast, the body measurements showed no differences. These results suggest that the Booroola Romney × Moghani crossbreed may be appropriate for a strategie to create a composite breed based on local Moghani sheep with expected increased prolificacy and optimal lamb growth rates taking advantage of the good maternal qualities of the Moghani ewes