Submitted to: Biology of Reproduction Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: May 1, 2004
Publication Date: August 20, 2004
Citation: Vallet, J.L., Freking, B.A. 2004. Further evidence for an association between a polymorphism in the erythropoietin receptor (EPOR) gene and litter size in pigs [abstract]. Biology of Reproduction. 70 (Supplement):152. (Abstract #259) Technical Abstract: We previously reported an association between a single nucleotide polymorphism (SNP) in the erythropoietin receptor (EPOR) gene and uterine capacity in lines of gilts selected either randomly, for ovulation rate or for uterine capacity. The SNP creates an extra GATA-1 site in the EPOR gene and thus may affect transcription. The objective of the current study was to confirm the association between this SNP and litter size in a population unrelated to the selection lines previously evaluated. The genotypes of 65 boars were determined retrospectively using DNAs isolated from tail tissue. The boars sired 746 first parity litters (n=4 to 58 gilts per boar) over 18 breeding seasons. The numbers of piglets born and born alive were recorded at farrowing. Forty-one boars were homozygous C (525 observations), 16 were heterozygous (198 observations) and 3 were homozygous T (23 observations; T creates the extra GATA-1 site). Data were analyzed using ANOVA (proc mixed). Least squares means for number born were 10.4±.3, 10.9±.3 and 11.1±.7 and for number born alive were 9.1±.3, 9.9 ±.3 and 10.2±.7 for litters sired by CC, CT and TT boars, respectively. The effect of boar genotype on the number born alive was significant (P=.02). Thus, as in the selected lines at MARC, the EPOR SNP T allele was significantly associated with increased litter size in gilts. Furthermore, because the association is with boar genotype, these data indicate that the effect on litter size is fetal in origin, and thus these results are consistent with the hypothesis that fetal erythropoiesis influences uterine capacity and litter size. Finally, these results suggest that this SNP could be useful in increasing litter size in swine.