Effect of polymorphism in the partial promoter of prolactin gene on age at sexual maturity in layer chicken

Prolactin is an important pituitary hormone affecting broodiness in chicken. As the promoter plays central role for regulating expression of the prolactin gene, the present study was conducted on prolactin promoter variability in IWH, IWI, IWK and control strain of White Leghorn chicken. Total 356 birds were genotyped employing SSCP method and all the alleles were sequenced. Five genotypes (AA, AB, AC, BB and BC) and three alleles (A, B and C) were found in these strains. The AB and AA genotype revealed the highest (0.80) and lowest (0.04) frequency, respectively while A and B allele showed the highest (0.47) and C allele had the lowest (0.06) frequency. A number of SNPs have been detected in this fragment. Genotype had significant effect (P < 0.05) on age at sexual maturity and BB genotype showed the lowest age at sexual maturity (149.79±3.55 days) while BC revealed the highest value (153.79±3.08 days). In conclusion, it may be stated that prolactin promoter was polymorphic and showed significant effect on age at sexual maturity.