Polymorphism of the ovocalyxin-32 gene and its association with egg production traits in the chicken

We performed candidate gene analysis to identify SNP in the chicken ovocalyxin-32 (OCX-32) gene in the F₂ resource population, to develop a PCR-RFLP method for genotyping and to evaluate the associations of the gene polymorphism with egg production traits. The F₂ resource population-comprising 272 chickens-was obtained by crossing White Leghorn (WL) males and Rhode Island Red (RIR) females. They were measured for egg production traits and used for candidate gene analysis. Among parental individuals of the F₂ population, 2 novel nonsynonymous polymorphisms (c.267T>G and c.494A>C) and 1 known non-synonymous polymorphism (c.381G>C) in the coding sequences of the chicken OCX-32 gene were detected. The PCR-RFLP method was used for screening the chickens of the F₂ population. In parental populations, genotype c.267T>G and c.494A>C were segregated within WL and RIR breeds, respectively, but genotype c.381G>C was breed-specific SNP between WL and RIR breeds. A total of 4 haplotypes were constructed based on the 3 SNP in parental populations, and there was no recombination between c.267T>G and c.494A>C. There was a significant association (P < 0.05) between the OCX-32 gene SNP and egg production traits, but there was no significant association between the hap-lotypes of the OCX-32 gene and egg production traits in the F₂ population. In the present study, there was the most significant association between c.381G>C of the OCX-32 gene and rate of egg production. The current study is the first step to confirm the relationship between OCX-32 gene polymorphisms and egg production traits.