B.J. Isler, K.M. Irvin, S.M. Neal, and S.J. Moeller. Department of Animal Sciences, The Ohio State University, Columbus, Ohio, 43210.
The association between a polymorphism in the estrogen receptor beta (ERb) gene and reproductive tract components in swine has been evaluated. The ERb genotype of 75 Yorkshire (Y ´ Y), 80 Large White (LW ´ LW), and 99 crossbred (33 LW × Y, 66 Y × LW) females was determined to be AA, AB, or BB using a PCR-RFLP procedure. All animals were mated to Hampshire or Duroc boars and slaughtered at approximately 75 days of gestation. Data collected from gravid uterine tracts included ovulation rate, uterine weight, uterine horn length, number of fetuses, total fetal weight, average fetal weight, number of mummies, fetal space, and fetal survival. Data were analyzed using a model that included the effects of ERb genotype, breed, parity, and significant two-way interactions. Uterine horn was also included in some analyses to determine the presence of between horn effects. ERb genotype was found to be associated (P < 0.1) with fetal weight per uterus, average fetal weight per uterus, number of fetuses per horn, fetal weight per horn, and average fetal weight per horn. Animals with the BB genotype had a significantly (P = 0.003) greater number of fetuses per horn (5.63 ± 0.51) than animals with the AA genotype (4.83 ± 0.15). BB animals also had a significantly (P < 0.05) smaller total (1687 ± 75 g) and average (335.4 ± 14.2 g) fetal weight per horn than AA animals (1821 ± 29 g, 368.7 ± 5.7 g). The ERb gene appears to act in a dominant manner, with the B allele being dominant over the A allele. Animals with the dominant phenotype gestate larger, lighter litters of piglets than animals with the recessive phenotype. Other traits displayed statistically non-significant trends with respect to the BB genotype: increased fetal survival and total number of fetuses per uterus and decreased uterine weight and fetal space per horn. The ERb gene is positively associated with several reproductive tract traits. This abstract was originally presented at the 2002 American Society of Animal Science national meeting in Quebec City, Quebec, Canada on July 21-25, 2002.