Detection of polymorphism in growth differentiation factor 9 gene (GDF9) Exon1 and its association with litter size in local Iraqi goats

Litter size is one of the most important economic traits in goats. Growth Differential Factor 9 (GDF9) Gene is suggested as a functional candidate for fertility, fecundity and twining rate. This study was performed to identify SNPs in exon1 of the GDF9 gene and their association with fertility traits in local Iraqi goats. The exon 1 of GDF9 was sequenced, and the SNP (Single nucleotide polymorphism ) was determined in 36 local Iraqi goats. Then the association analyses between polymorphic locals of GDF9 and litter size were performed using the chi-square analysis procedure. The result shows that mutation (C 1902 G) was significantly associated with litter size in local Iraqi goats and the location of C1902 G mutation with three genotypes CC, CG and GG. A significant effect was found for birth weight, weaning weight and twin ratio, where the homozygous dominant genotype outperformed CC. A significant impact was seen for fertility and mortality, where CC topped CG and GG in fertility percentage and superiority of CG over CC and GG in mortality rate. The results preliminarily demonstrated that GDF9 was a critical gene affecting the fecundity of local Iraqi goats and that (C 1902 G) could be a potential genetic marker.
 
Keywords: GDF9 gene, litter size, polymorphism, Iraqi goats