Association of polymorphisms in the intron 1 of duck prolactin with egg performance

Gaoyou duck (Chinese indigenous breed) is famous for double-yolked egg. In the present study, SNP of prolactin (PRL) gene intron 1 of Gaoyou duck was detected by PCR-RFLP and DNA sequencing. The results indicated that there were 2 Dra I recognition sites in intron 1 of the PRL gene, but only 1 was of polymorphism. A T/C mutation at the position of the 1326 bp of the PRL gene was found by DNA sequencing, and resulted in 3 genotypes AA, AB, and BB. The frequencies of genotype BB and allele B were the highest. The association analysis between the polymorphism PRL gene intron 1 and egg performance was carried out. The least square analysis showed that the BB ducks had significant egg weight at the age of 30 weeks than AB ducks (P < 0.01), the double-yolk percentage of the AB ducks was much higher than that of BB ducks (P < 0.05) in double-yolk ducks, but there was not significant difference in egg number, longest clutch days, and the body weight at first egg among the three genotypes.