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Genetic variations in the bone morphogenetic protein 15 (BMP15) gene exert a major effect on the ovulation rate in sheep. This study was conducted to investigate the polymorphisms of the BMP15 gene and its association with twining performance in two breeds of Awassi: purebreds and crossbreds. Two loci were genotyped within the exon 2 of the BMP15 gene, B2 and B4 amplicons. PCR–single-strand conformation polymorphism (SSCP) method indicated the presence of two genotypes in B2 amplicons, TT in purebreds and TA in crossbreds. Two novel SNPs were identified in the B2 amplicons, Asp238Glu, which was detected in both studied breeds, and Phe255Leu, which was detected only in crossbreds. Asp238Glu was predicted to have a highly deleterious effect on protein structure and function. Sheep with TA genotype showed 87% of twining ratio compared with sheep with TT genotype that exhibited only 48.3%, signifying an obvious superiority of TA genotype over TT genotype. In conclusions, the non-deleterious Phe255Leu is associated with higher litter size in crossbreds, while the deleterious Asp238Glu is associated with the observed lower litter size on the purebreds. The present study demonstrated the presence of a highly positive effect of Phe255Leu on BMP15 protein, manifesting in a possible improved prolificacy in the ovine population.

This study was conducted in Barakat Abu al Fadhl Al- Abbas station (AS) for raising sheep/a subsidiary of Al- Kafeel Company for General Investment and livestock services in Holy Karbala province and Babylon Province It was undertaken on Awassi sheep for between October, 2013 to May, 2014 to investigate the polymorphism of TGF-B gene and its association with reproductive traits of Awassi sheep. Blood samples were collected from (80) ewes included 35 samples of Awassi ewes producing twins (pure breed), 21 samples of Awassi ewes producing twins lambs (hybrid breed), also 25 samples of Awassi ewes producing single lambs (pure breed), with age (2 .5- 5) years. DNA samples were extracted from each blood sample of sheep. Reference PCR primers were utilized to amplify segments in TGF-B Super Family gene. Then, AFLP technique was performed for each PCR fragment. The results indicated that two genotypes for each of the fragments of TGF-B Super Family gene (AF and FF) were identified. TGF-B Super Family gene revealed two fragments (156 and 245 bp) for FF genotypes and three fragments (156, 254 and 410 bp) for AF genotypes. PCR- AFLP methods detected two genotypes (AF and FF) with predominant of AF genotype in Awassi ewes producing twin, and this study refers to utilizing TGF-B gene as good genetic markers and their correlation with high fertility and twins producing Awassi sheep.