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Advantages of OPU-ICSI in equine reproduction

Ovohorse OPU

At Ovohorse, leaders in equine reproduction and animal cloning, we have put together a guide of the advantages of using OPU-ICSI over other reproduction treatments such as insemination or embryo transfer.

OPU (ovum pick-up) is the initial process by which the egg cells are retrieved from the donor mare. The eggs are directly extracted from the mare’s ovaries using a transvaginal route and transvaginal ultrasound as a guide (TVA). During the treatment, the mare is continually monitored by the veterinary team, and after the OPU procedure, is treated with antibiotics and painkillers until fully recovered. Approximately three days after the OPU, the mare can return to her routine, as long as she does not have training or competition. The risks associated with this technique are extremely low, but as with any procedure, complications can occur.

One of the main advantages that OPU-ICSI has is that thanks to the technique of follicular aspiration (ovum pick-up) and the subsequent fertilization of the egg with the sperm in the laboratory (ICSI), more embryos can be achieved than with traditional reproductive techniques.


If you have a competitive mare, it is important that you bear in mind that she can undergo oocyte aspiration every 20-25 days during the whole year. This advantage allows us to significantly increase embryo production, with, on average, two embryos being produced in each OPU-ICSI session.

Some of the many advantages are:

  • OPU-ICSI can be performed all through the year
  • The technique of OPU-ICSI can be carried out during any reproductive phase of the mare
  • OPU-ICSI is possible in the first third of the gestation period.
  • It can be performed with mares who have reproductive problems (uterine, reproductive tract, hormonal imbalances)
  • Embryos can be produced from a single visit to the mare
  • Resulting embryos can be vitrified indefinitely in liquid nitrogen
  • Vitrified embryos can be exported to, and sold in, all parts of the world
  • The embryos can be thawed at the most suitable moment according to the time of the year, the breeder’s needs, location, number or condition of the recipient mares.


In the case of high-value stallions or those who have a long sporting career, OPU-ICSI is one of the best options if you want to preserve the stallion’s legacy without interrupting his career.

The advantages of carrying out OPU-ICSI with a semen sample are as follows:

  • Only one sperm cell is needed per egg
  • Various embryos can be produced from a sperm sample
  • A straw of frozen sperm can be cut, and then used to cover various mares who have been aspirated.
  • OPU-ICSI is the ideal technique for stallions with poorer quality sperm, low availability, low sperm count or quality or for high-cost straws.
  • Material can be recovered from straws that have been poorly frozen, or that have lost quality due to being processed many years ago



The transfer of equine embryos obtained after OPU-ICSI also has advantages over traditional techniques of reproduction or transfer. In this case, after the OPU-ICSI is performed and obtaining the expected number of embryos, the breeder can decide to transfer them immediately or preserve them for future pregnancies. The embryos can be safely preserved in liquid nitrogen indefinitely, maintaining all their properties and potential they had at the time of production.

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