A new HpaII PCR-RFLP within the porcine prolactin receptor (PRLR) gene and study of its effect on litter size and number of teats

DNA polymorphism of the porcine prolactin receptor gene ( PRLR ) was investigated and used to study its effect on litter size and number of teats in pigs. By means of PRLR gene sequence homology in pig, human and other species, primers were designed for PCR amplification within 5' unknown (to date) part of the prolactin receptor gene in pigs. In this part of the gene, a new polymorphism with Hpa II restriction endonuclease was detected. Alu I polymorphism described before and our new Hpa II polymorphism were used to study the associations with reproduction traits. The PCR restriction fragment length polymorphism (PCR-RFLP) method was used to genotype Alu I and Hpa II loci of the PRLR gene in line A with 83 sows of Landrace breed and in two lines (B and C) with 75 and 86 Large White sows, respectively. Statistical analysis of 1020 litters showed that Alu I locus was associated with litter size mainly in Landrace and affected the first parities, while Hpa II locus of the gene was associated with the same traits in Landrace and Large White pigs and mainly affected numbers of weaned of pigs. The magnitude of the effect varied by population with the effects exceeding two pigs per litter in Landrace line and 1 pig per litter in Large White populations.