Molecular Characterisation of BMP15 and GDF9 Genes and Their Association with Litter Size in Awassi Ewes from Northern Iraq

Abstract

The study examined variations in the BMP15 and GDF9 genes and related them to litter size among Awassi sheep from Northern Iraq. We took blood from 120 ewes and separated them into groups with high and low numbers of lambs, depending on their reproductive history. From PCR-RFLP, SSCP and DNA sequencing, five different locations on BMP15, including the FecXI and FecXH mutations, were detected, along with six different locations on GDF9, including G1 and G4 variants, while there were five entirely new mutations discovered in both genes. There was a clear link between these polymorphisms and litter size (p<0.001) and carrying one copy of the heterozygous gene was linked to having more offspring. Litter size was increased by 0.56 lambs with FecXI (g.321C>T) and FecXH (g.528G>T) and by 0.54 lambs for G1 (g.260G>A) and G4 (g.477G>A) in GDF9. Ewes with double mutations had 23% more offspring per group (2.21±0.07) than those that were mutant only for GDF9 or BMP15. Out of the mutations examined, most were predicted to have negative effects by bioinformatic analysis and structural changes were seen in protein modeling of related functional regions. According to the integrated model, gene effects contributed 65% to the variance in phenotypic results. The results provide useful information for genetically upgrading Awassi sheep and indicate that using multiple genomic markers at once can increase the reproductive efficiency of these sheep.