Abstract
This study aimed to investigate the relationship between GH, GHR, IGF-1R, VIP, and NPY genes and egg quality traits in laying hens. Atak-S laying hens aged 54 weeks were monitored for 6 weeks. Egg production and egg weight were recorded daily, while egg quality traits and feed consumption were assessed weekly. Genotyping was performed using PCR-RFLP. The GH, GHR, IGF-1R, VIP, and NPY genes were cut with MspI, HindIII, HinfI, HinfI, and DraI, respectively. The AA genotype of the GH gene was associated with increased egg shape index, eggshell weight, and eggshell thickness (p < 0.05). In the IGF-1R region, significant associations were found with egg weight and egg shape index (p < 0.05). Additionally, the VIP12 TT genotype was linked to higher egg production (p < 0.05). These findings suggest that the GH gene may serve as a selection marker for shell-related traits, IGF-1R for egg weight and egg shape, and VIP for improving egg production. Overall, the results obtained in this study indicate that the genes studied have the potential to be candidate markers for improving egg performance and quality; however, their use in marker-assisted selection requires further studies in larger and more diverse populations.