Clinical Application of in Vitro Embryo Production in the Horse.

The research article focuses on the advancements and utilization of in vitro embryo production (IVEP) in horse breeding practices, outlining how it has become more efficient and successful than older methods over the past decade.

Background and Past Concerns

• The study first outlines that in vitro embryo production (IVEP), which includes conventional in vitro fertilization and intracytoplasmic sperm injection, was first reported in horses approximately 25 to 30 years ago.
• However, despite the early introduction of the technology, IVEP didn’t become routinely used in clinical practice until about a decade ago. The delay is attributed to the low success rate of these techniques, which made it an uneconomical means of breeding horses.

Advancements and Improved Success Rates

• In the past decade, the effectiveness of IVEP has improved significantly. The researchers highlight two main areas of improvements: the increased efficiency in recovering immature oocytes (ovum or egg cells) from live donor mares and the improved success in cultivating zygotes (fertilized eggs) to the blastocyst stage.
• Historically, the success rate of recovering immature oocytes used to be below 25%. Now, the success rate has surpassed 50%. Similarly, the percentage of successfully nurturing zygotes to the blastocyst stage, used to be less than 10%, has increased to over 20% presently.
• Oocytes can now be stored at room temperature for at least 24 hours, which allows for their transportation to a specialist IVEP laboratory. Also, in vitro produced embryos can be cryopreserved with no significant reduction in their viability. This means they can be shipped and stored until a suitable recipient mare is ready for the transfer.

Increased Efficiency and Demand

• Crucially, the article mentions that an equine ovum pick-up intracytoplasmic sperm injection (OPU-ICSI) program now produces more than one blastocyst per procedure, and the post-transplant foaling rate excels 50%.
• This efficiency beats that of older methods such as embryo flushing or oocyte transfer. Another advantage of OPU-ICSI is that it can be conducted throughout the year and enables the production of embryos from mares with severe acquired subfertility and extremely effective use of costly or scarce frozen semen.
• As a result of these developments, there has been a reported increase in demand for IVEP among sport horse breeders.