A substitution within erythropoietin receptor gene D1 domain associated with litter size in Beijing Black pig, Sus scrofa

Abstract

Studies of uterine capacity and litter size in swine have suggested that erythropoietin receptor (EPOR) plays an important role in fetal survival through maturation of red blood cells. In this study, we screened the porcine EPOR gene for mutations and identified three single nucleotide polymorphisms (SNPs): two missense mutations and one synonymous mutation. We then genotyped 272 Beijing Black sows, Sus scrofa, and compared this data with litter sizes from a total of 1523 parities among the sows. The G allele of the nonsynonymous SNP, EPOR c.434A>G, was associated with greater litter size at both first parity (P < 0.05) and at later parities (P < 0.01). This SNP causes His92Arg adjacent to the fourth conserved cysteine residue in the mature protein and is in the D1 domain of the protein. Additionally, we determined the allele frequencies for this SNP among six Chinese indigenous pig breeds (Bamei, Erhualian, Laiwu Black, Mashen, Meishan and Min) and three Western commercial pig breeds (Duroc, Landrace and Large White). The c.434G allele was significantly more common among the more prolific Chinese breeds than the Western breeds, implying that EPOR c.434A>G could be a useful genetic marker to improve litter size in swine.