ASSOCIATION OF POLYMORPHISM IN PROLACTIN (PRL) PROMOTER REGION AND PROLACTIN RECEPTOR (PRLR) EXON 5 WITH EGG PRODUCTION AND EGG QUALITY TRAITS OF DARAG PHILIPPINE NATIVE CHICKEN

Abstract

Prolactin (PRL), through the mediation of its receptor (PRLR), initiates and sustains the broodiness of chickens, leading to reduced egg production. Association of polymorphisms in the PRL promoter region and PRLR exon 5 with egg production and egg quality traits of Darag were then investigated. Hens (n=41) were genotyped using indel and SNP markers. Indel analysis identified three PRL genotypes: II with 154 bp, ID with 154 and 130 bp, and DD with 130 bp. The DD genotype and the D allele had the highest frequencies at 0.54 and 0.77, respectively. The ID genotype had heavier egg and yolk weights, and higher egg length (P<0.05) than DD genotype, while total egg number and shell weight tend (P<0.10) to be different between genotypes. In most indigenous breeds of chickens, the D allele is more predominant than the I allele. Further, the ID genotype of PRL is more favorable than DD genotype in certain egg quality traits. However, for PRLR, all hens were monomorphic (AA) at the genotyped loci in exon 5. In conclusion, the association of ID genotype of PRL with egg quality was established, and thus, PRL genotypes may be used as a basis for selection.