Embryo Transfer

Equine embryo transfers provide new opportunities for horse owners and mares. The procedure involves removing a very young (7-8 day) embryo from a valuable donor mare and transferring it into the uterus of a recipient mare to complete development.

Although the foal is born and nursed by the recipient mare, it is the genetic offspring of the donor mare.

Embryo Transfers allow

• Mares to continue performance careers,
• Outstanding mares to have more than one offspring per year,
• Obtain foals from problem and aged mares, and
• Immature two year olds to produce offspring.
• Production of foals from late foaling mares

Freezing of the embryo allows

• Time to select the perfect recipient mare
• Banking genetic information of the mare for future use
• Shipment of embryos worldwide

The Procedure

Donor Mare

Initially, we treat the donor mare in a similar manner to any other breeding mare.  Her cycle is monitored by a rectal/ultrasound examination and breeding is timed according to these findings.  Seven or eight days after ovulation is detected, we place a catheter into her uterus and the embryo is removed by a flushing technique that utilizes a special fluid.  The microscopic embryo is then located in the flush fluid and is prepared for transfer.

Recipient Mare

The recipient mare is the mare into which the embryo will be placed for complete development, birth and nursing.  The recipient mare, which should be young and reproductively healthy, must ovulate in a 48 hr. window following the donor mare.  Should you own a suitable recipient mare, her cycle can be medically manipulated to encourage her to ovulate in this time frame.  If your proposed recipient mare does not ovulate in the appropriate window, a mare provided by LACER, will be available as an alternative.  If you do not own a suitable recipient mare, a LACER mare can be your primary option.  Once the pregnancy is established, you will lease this mare for the duration of pregnancy through weaning of the foal.

Success Rates

Collection rates of equine embryos vary greatly according to the reproductive health of the donor mare.  Young, healthy mares with no history of reproductive problems typically provide embryo recovery rates near 80%.  Successful embryo recovery from older, sub-fertile mares varies with the individual, but is near 30% as a group.

Once the embryo is successfully recovered, transfer rates are approximately 80% for high quality (grade I & II) embryos.  A 10% pregnancy loss during the first 50 days of pregnancy corresponds to the average pregnancy loss due to naturally occurring maternal and/or fetal problems.

Cryopreservation and Embryo Vitrification