Combined Genotype Effects of PRLR and GH Polymorphisms on Litter Weight in Kilis Goats

This study investigates the relationship between polymorphisms in the PRLR, GH1, and GH2 genes and their impact on litter weight in Kilis goats, a native breed of significant economic importance in Türkiye. Within the scope of the research, a total of 198 goats were used under breeder conditions in Kilis Province. This study was conducted as part of the National Small Ruminant Breeding Project, coordinated by the Ministry of Agriculture and Forestry of the Republic of Türkiye and implemented by the General Directorate of Agricultural Research and Policies (TAGEM). Allele frequencies for the PRLR/RsaI, GH1/HaeIII, and GH2/HaeIII loci were analyzed, revealing that the C allele at PRLR/RsaI and the D allele at GH2/HaeIII were the most prevalent in this population. While no significant differences in litter weight were observed among PRLR genotypes (P > 0.05), significant associations were identified between the GH1 and GH2 loci and litter weight (P ≤ 0.05). Specifically, Kilis goats with the AB genotype at GH1 and the CD genotype at GH2 exhibited significantly higher litter weights compared to other genotypes, highlight the potential influence of these genetic variations on reproductive performance. Furthermore, significant genotype interactions were observed, with the highest litter weight recorded in goats carrying the AB-CD genotype combination (7.613 ± 2.973 kg). These findings suggest that genetic variations at the GH1 and GH2 loci play a critical role in determining reproductive traits such as litter weight. Strategic breeding programs targeting these loci could enhance productivity in Kilis goats. Given the economic significance of litter weight in livestock production, these results provide a foundation for further research into the genetic basis of reproduction traits in goats. Additional studies across diverse breeds and environmental conditions are necessary to validate these findings and explore the broader implications for genetic selection in livestock breeding.