Genetic diversity of porcine PRLR gene and its relationship to litter size in Large White pigs

Improving the litter performance of sows is one of the main challenges in the current pig industry. In this study, single nucleotide polymorphisms (SNPs) of the PRLR gene were performed, in order to test whether they are associated with the reproductive performance of Large White pigs. In total, we discovered nine SNP loci (g. C260G, g. C362T, g. C527G, g. A540G, g. A584G, g. A673T, g. A745G, g. C765T and g. A934G) in exon 10 of PRLR. The result showed that genotypes CC and CT at the g. C362T locus and genotype AG at g. A584G could significantly increase the litter size of different strains of Large White pigs (p < 0.05). In addition, the genotype CC at the g. C765T locus and the genotype AA at g. A934G could also increase the litter size (TNB could be increased by 1.5 piglets per year; while NBA could be increased by 0.98 piglets per year, p < 0.01). Furthermore, the haplotype combinations of H2H7 and H4H4 were the dominant combinations and contributed to larger litter sizes in the Large White pigs. In conclusion, there were dominant genotypes in the related SNP loci in the PRLR gene that were beneficial to improving the litter traits of sows. These findings will provide a reference for screening the molecular markers of a high reproductive performance in sows, and are helpful for genetic breeding and the reproductive improvement of pigs. Key words: sow, prolactin, polymorphism, reproduction, association analysis.