Polymorphisms analysis of the prolactin gene with egg production traits in two Chinese domestic ducks.

Prolactin (PRL) as a polypeptide hormone which plays a crucial role in egg production traits. Polymorphisms of the PRL gene were analysed with DNA sequencing and polymerase chain reaction-single-strand conformation polymorphism methods in two Chinese domestic laying duck breeds (Jinding n=400, Youxian n=400, respectively). The results showed that one polymorphism was detected (A-412G) in intron 1 of the PRL gene, with three genotypes: AA, AG, and GG. Association analysis showed that the ducks with the GG genotype had significantly greater egg production and egg weight than those with AG and AA genotype (P<0.05). Hence, the 412A>G polymorphism of the PRL gene in intron 1 is a potentially valuable genetic marker for laying duck breeding programs.