Polymorphism of Prolactin Receptor Gene and its Association with Egg Production Traits in Erlang Mountainous Chicken

Prolactin Receptor (PRLR), as an important regulatory gene about growth and differentiation, might be a candidate gene for reproductive traits. The purpose in the present study was to analyze the association of Single Nucleotide Polymorphisms (SNPs) of exon 6 in prolactin receptor gene with egg production traits in Erlang mountainous chickens, a native breed from Poultry farm of Sichuan Agricultural University which consisted of two pure lines SD02 and SD03. Polymerase Chain Reaction-single-strand Conformation Polymorphism (PCR-SSCP) and DNA sequencing methods were used. Results showed that One SNP (G1836C) which had not yet been reported was found and two alleles (G, C) and two genotypes (GO, CC) were also detected. It observed significant differences in allelic and genotypic frequencies among all the chicken populations. Genotype frequencies in all chicken for GG and CC were 56.22 and 43.78%, respectively. Associations of polymorphisms of the PRLR gene with egg production traits were analyzed by using a GLM procedure. The CC genotype had extremely significant effect on Age at First Egg (AFE) (p<0.01) and the AFE of CC genotype had 3.75 days earlier than GG genotype. There was no significant association of G1836C with BWFE; body weight at first egg, WFE; weight at first egg, EN; egg number during 300 days after hatch, BWTA; body weight at 300 days of age and WTE; egg weight at 300 days of age. Therefore, the study showed that the PRLR gene may either a major gene that influences age at first egg of chicken or a molecular marker in close linkage with such a gene.