OPU & ICSI
For mares with subfertility issues or those unable to produce embryos via traditional methods, Ovum Pick-Up (OPU) and Intracytoplasmic Sperm Injection (ICSI) is an advanced breeding technology that offers a solution. This method is ideal for mares who are not cycling, have limited fertility, or for using rare or limited availability semen.
Ovum Pick-Up
OPU involves the collection of eggs (oocytes) directly from the follicles in the mare’s ovaries. Our specialist vets use ultrasound-guided aspiration under standing sedation or epidural anaesthesia to retrieve the oocytes. The oocytes that are obtained are then shipped to specialist laboratories in Europe, where they are matured and then the ICSI procedure is performed.
Intracytoplasmic Sperm Injection (ICSI)
During ICSI, a single sperm cell is injected directly into each mature oocyte, bypassing many of the natural barriers to fertilisation.
Following ICSI, fertilised oocytes are then cultured for 7–9 days where they develop into embryos (blastocysts), before being frozen and transferred back to Twemlows for implantation or stored for future use.
Advantages of OPU & ICSI
- Ideal for subfertile mares unable to produce an embryo for embryo transfer or unable to carry a pregnancy to term
- Can be carried out outside the normal breeding season as mares do not have to be cycling
- Little interruption to competition work
- Frozen embryos can be transferred to a recipient mare, stored until a later date or sold when the owner desires
- Use of a very small amount of semen allows subfertile stallions or exclusive/expensive semen to be used more effectively. One straw of frozen semen can be used for multiple ICSI sessions
- In case of sudden death/euthanasia oocytes can be recovered as soon as possible post mortem and undergo ICSI (Genetic Salvage)
Success Rates
Oocyte retrieval rate can vary and could be between 50 – 70%, however this will depend on the individual mare. The more follicles she has the more oocytes you expect to recover.
Once retrieved and sent to the lab, oocytes must mature before they can undergo ICSI. It can be expected that 60-80% of oocytes will reach this stage. The average number of embryos produced per OPU session is 2.
Transfer of a frozen embryo from OPU & ICSI have success rates around 70%. It has to be noted that whilst many mares are successful at producing embryos via OPU-ICSI, some mares will fail.
To talk to one of our vets about the procedure, please do not hesitate to contact us:
Other Comments / Requirements for Donor Mares:
- Health papers need to accompany each oocytes export
- APHA CEM swabs and EIA blood test should be completed ahead of the OPU procedures
- The mare must not have been outside the UK 90 days before the OPU or between her health tests and the OPU
- Mares should have at least 12 follicles of around 1-2 cm diameter to maximize the chances of oocyte retrieval
- Frozen semen for the ICSI should be available/be shipped ahead of the OPU to the European laboratory
- OPU can be repeated at 21-28 days intervals assuming enough follicles have developed in the meantime