B. J. Isler*, K. M. Irvin*1, S. M. Neal‡, S. J. Moeller*, M. E. Davis*,
and D. L. Meeker*
*The Ohio State University Department of Animal Sciences
‡The Ohio State University Agricultural Technical Institute
Previous studies have shown that a specific allele (B allele) of the estrogen receptor (ESR) locus is associated with increased litter size in swine. At this time, research is lacking in the examination of the association between ESR genotype and the reproductive system itself. The objective of this current study was to investigate the association between ESR genotype and reproductive components in swine. The ESR genotype of 322 Yorkshire (Y(Y), Large White (LW(LW), and crossbred (LWxY, YxLW) animals was determined to be either AA, AB, or BB using a PCR-RFLP procedure. Of this group, 107 females were selected and mated to Hampshire boars. At approximately day 75 of gestation, the females were slaughtered and their reproductive tracts collected. Data collected included ovulation rate, horn length, number of fetuses, fetal mass, uterine mass, number of mummies, fetal sex, fetal placement, fetal survival, and fetal space. Data were analyzed using a model that included ESR genotype, breed, parity, and significant two-way interactions. Uterine horn was also included in some analyses. ESR genotype was not found to be a significant (P > 0.05) effect for any of the traits studied. Some traits displayed favorable, but not statistically significant, trends with respect to ESR genotype – fetal survival, total uterine length, total fetal weight, total number of mummies, fetuses per horn, horn length, and fetal space. The ESR gene, therefore, appears to be positively associated with several reproductive traits. Parity and breed also affected some reproductive traits. Animals of parity >= 3 had both a significantly (P < 0.05) larger ovulation rate per horn (+1.78 ova) and a lower fetal space per horn (-16.01 cm) than animals of parity 1. Also, animals with a Large White dam had an increased number of fetuses per horn, increased fetal weight per horn, and a decreased fetal space per horn.
1 For more information, contact at: The Ohio State University, 110F Animal Science Building, 2029 Fyffe Road, Columbus, OH 43210, 614-292-6407, Fax 614-292-2929, e-mail: irvin.3@osu.edu