Effect on Pregnancy in the Pig after Killing Embryos or Fetuses in One Uterine Horn in Early Gestation

Abstract

One hundred and sixty-nine gilts, 6 to 10 mo. old, were used to investigate the influence of killing embryos or fetuses in one uterine horn at times from day 4 to 50 of gestation on continued pregnancy in the gilt. Treatment consisted of either killing in situ, flushing or stripping the embryos from one uterine horn. The intact horn was ligated twice near the uterine body to prevent entry of embryos or embryonic membranes into the treated horn. Uteri of control gilts were also ligated and no effect of ligation alone was seen. There was no difference (P>.05) between treated and control gilts in the proportion of gilts maintaining pregnancy when treated between days 12 and 50. None of the gilts treated at days 4 and 10 maintained pregnancy. It is concluded that embryos must be present in both uterine horns between days 10 and 12 for continuation of pregnancy, while embryos need be present in one horn only after day 12. Corpora lutea of normal appearance were present at autopsy on both ovaries in all except three of the gilts pregnant unilaterally. In the three exceptional gilts, the CL had regressed on the ovary adjacent to the nongravid horn.