Association of RAPGEF6 Gene Polymorphism with Some Traits and Egg Production Covariance Structure in Marandi Chickens

Sustaining egg production is crucial for the economic viability of layer farms. The Marandi chicken, a well-known native breed from Iran’s Azerbaijan region, has the inherent capacity for high egg production, reaching up to 250 eggs annually. However, its genetic potential remains largely untapped. This research explores the relationship between the RAPGEF6 gene and key performance indicators in 153 Marandi hens, using molecular markers to analyze complex economic traits. Production, reproduction, and performance data were examined through repeated-measure and single-record models. The RAPGEF6 genotype at the 13:16120088–16120089 locus was identified via PCR-RFLP, and its connection to phenotypic variation was evaluated. Results showed that the RAPGEF6 genotype had little effect on most traits; however, hens with the TT genotype displayed significantly lower maturity weight compared to the TC and CC genotypes. Additionally, a mixed-effects model, which for the first time included an analysis of the covariance structure (ARMA (1,1)) to account for repeated egg weight records from individual hens, revealed no significant link between RAPGEF6 genotype and egg weight. These findings suggest that selecting for the T allele could be a viable strategy to reduce maturity weight in Marandi layer chickens, potentially improving overall production efficiency. Further studies are needed to better understand the genetic factors influencing egg production traits in this breed and to verify these results in larger populations.