EFFECTS OF CERVICAL-DILATION AND INTRAUTERINE INFUSIONS ON THE TIMINGOF OVIDUCTAL TRANSPORT OF EQUINE EMBRYOS

Equine embryos spend 5 to 6 d in the oviduct before entering the uteru s as expanded blastocysts, and cannot be consistently collected nonsur gically until Day 7. Technologies such as cryopreservation and embryo splitting, which are most successful with embryos at the morula or ear ly blastocyst stage, have not been used in mares because equine morula e and early blastocysts are located in the oviduct and cannot be recov ered nonsurgically. These experiments test the hypothesis that transpo rt of equine embryos through the oviduct can be hastened by cervical d ilation or by acute, sterile endometritis induced by intrauterine oyst er glycogen treatment. Cervical dilation with or without intrauterine infusion of 0.5 ml PBS on Day 4 did not appear to hasten the transport of embryos into the uterus since Day 5 uterine embryo recovery rates were not higher (P >0.1) for mares with cervical dilation or cervical dilation plus PBS infusion vs mares receiving no treatments (0 of 5 an d 0 of 5 vs 0 of 10, respectively). Intrauterine infusions of 40 ml of 1% oyster glycogen or 40 ml of PBS on Day 3 did not appear to hasten the transport of embryos into the uterus since Day 5 uterine embryo re covery rates were not higher (P >0.1) for oyster glycogen- or PBS-trea ted vs untreated mares (2 of 12 and 3 of 11 vs 0 of 10, respectively). Cervical and uterine treatments on Day 3 or Day 4 and uterine lavages on Day 5 decreased (P <0.05) Days 11 to Day 15 pregnancy rates compar ed with that of untreated mares. Day 11 to Day 15 pregnancy rates were 1 of 5 for mares with Day 4 cervical dilation and Day 5 uterine lavag e, 1 of 5 for mares with Day 4 PBS infusion and Dy 5 uterine lavage, 2 of 12 for mares with Day 3 oyster glycogen infusion and Day 5 uterine lavage, and 3 of 11 for mares with Day 3 PBS infusion and Day 5 uteri ne lavage vs 7 of 10 for mares that received no treatment or lavage. C ervical and uterine manipulations on Day 3 or 4 and uterine lavage on Day 5 appeared to decrease pregnancy rates by Days 11 to 15. The resul ts of these experiments do not support the hypothesis that cervical di lation or uterine infusion hasten oviductal transport, since neither c ervical manipulation nor transcervical infusion of oyster glycogen or PBS into the uterus significantly hastened the rate of embryo transpor t into the uterus.