Polymorphism of the Prolactin Gene in Egyptian Duck Breeds

In avian, the prolactin hormone triggers and regulates ovarian follicle development. This study aims to detect the Prolactin (PRL) gene polymorphisms (exons 1and5) in four Egyptian duck breeds, namely Campbell, Moulard, Muscovy, and Pekin using PCR-RFLP technique and sequence analysis. It also investigated the association of this gene with egg production, egg weight, and body weight. The present results revealed that PRL gene exon 1 and part of intron 1 showed two alleles A and B (polymorphic) in each of Campbell and Moulard, however, Muscovy and Pekin had only one allele (monomorphic). The allele A was more dominant with frequencies of 0.70, 0.60, and 1.00, compared to the allele B (0.30, 0.40, and 0.00) for Campbell, Moulard, and Muscovy, respectively. For Pekin, the allele B only appeared with the frequency of 1.0. Ducks with the high frequency of allele A were superior at egg weight, compared to others. Furthermore, for PRL gene exon 5, there were two alleles G and C (polymorphic) in Campbell, Moulard, and Muscovy, however, Pekin had only one allele (monomorphic). The allele G was more dominant (0.15, 0.74, 0.0, and 0.84) than the allele C (0.85, 0.26, 1.0, and 0.15) for Campbell, Moulard, Pekin, and Muscovy, respectively. Ducks having a high frequency of allele C were superior at egg production. Furthermore, there were many single nucleotide polymorphisms (SNPs) in the sequences in all breeds. The utmost ones exist at the restriction sites of XbaI enzyme for the amplified fragment, in the promotor, exon 1 and intron 1 (T378C in intron 1), and DraI enzyme for that in exon 5 (A5871G in exon 5).