Investigation of Diversity in Exon 4 of Growth Hormone Gene and Relationship with Milk traits and Litter Size in Khalkhali Goats

This study was performed to investigate genetic variation of growth hormone gene and association analysis on important traits in Khalkhali dairy goats. PCR-SSCP method and Sanger sequencing were used for genotyping. In total, four different Polymorphic SSCP patterns were detected in the amplified region that leads to identify 5 mutations in exon 4 of growth hormone gene. In total we observed four haplotypes that were related to the polymorphic patterns. The frequency of haplotypes I, II, III and IV were 0.24, 0.46, 0.17 and 0.13, respectively. The results showed significant effect of   haplotypes on milk yield, milk fat and protein percentage of Khalkhali goat (p<0.05), but there is no association with milk lactose and solid matter percentage (p<0.05). Variations observed in this study made effective difference in litter size. Animals with haplotype II showed the most litter size with 2.159 kids in average and haplotype IV has the lowest with 1.40 kids per animal. The results of this study indicated that haplotype II (for litter size) and haplotypes IV, II, I (for milk yield and milk composition) could be considered as a marker in marker-assisted selection for improving the traits in khalkhali goats.