Scientific advancements in equine genetics and breeding processes have grown exponentially in the past decade. From the identification of genetic diseases to the discovery of new color genes, from new methods to harvest eggs to advancements in the preservation of semen, it can sometimes be challenging to keep up with the science behind breeding.
Now, it is possible to breed stallions who have passed away and successful mares to allow them to have multiple foals a year. The most common processes to enable these outcomes are frozen semen, embryo transfers, and Intracytoplasmic Sperm Injection, also known as ICSI.
We spoke to Amy Gumz of Gumz Farms, who currently stands the stallions Enticed, Florida Georgia Line, No Doubt Im Lazy, and the late Its A Southern Thing, to get her take on the value of frozen semen and ICSI process in the current breeding climate.
Defining The Terms
Before we get into the nitty gritty of Gumz’s observations, we want to clarify the scientific processes behind the scenes.
Frozen Semen
According to UC Davis Veterinary School, the collection process for freezing semen is the same as for cooling semen. However, once the semen is collected, the processes divert.
When preparing semen for freezing, it is mixed with a centrifugation extender, and most seminal plasma is removed by centrifugation (aka spinning it fast to separate the materials).
The resulting sperm is then resuspended in a freezing extender containing a nutrient medium and a cryoprotectant. This mixture of sperm and extender is then loaded into straws. The straws are then lowered in temperature by being exposed to liquid nitrogen vapor for a timed period. After the completion of that timed period, they are plunged into the liquid nitrogen, from which they can subsequently removed and stored in a liquid nitrogen storage container.
Frozen semen is stored in liquid nitrogen in specially designed vacuum containers that maintain a constant minus -320° Fahrenheit. Due to the sensitive nature of the viability of the semen, it is recommended that the mare be thawed by a reproductive veterinarian with experience with frozen semen before breeding it. If properly stored, the frozen semen can last indefinitely.
Because of this more complex process, stallion owners typically require additional fees or surcharges for frozen semen.
ICSI (Pronounced Ick-See)
According to the Colorado State University Equine Reproduction Laboratory, ICSI is a procedure that involves retrieving immature oocytes (eggs) from a mare and then injecting them with a single sperm cell (a process akin to in-vitro fertilization for humans). The fertilized oocyte is returned to an incubator to support its development into an embryo reaching transferrable quality, typically within 6-8 days. Given the nature of the procedure, it is often possible to retrieve multiple oocytes and inject them all – resulting in numerous embryos from a single round of ICSI.
So long as the embryo develops appropriately, it can be transferred into any mare whose cycle is aligned with implantation (known as a fresh transfer), or it can be frozen and transferred into a recipient mare at a later date – even years later.
More People are Investing in Advanced Breeding Technologies
Gumz has noticed a significant trend toward using these advanced breeding procedures in the last 5-10 years.
“I think there are two main reasons advanced breeding technologies are taking off in the pleasure horse industry. First, labs are becoming more proficient in the various procedures, resulting in higher success rates. Second, the advances are happening rapidly, which has decreased the costs of some procedures that have been around for a while.”
She continues, “Frozen semen has made it possible to ship semen overseas, thereby opening up new gene pools – particularly beneficial for smaller breed associations. Its use has also allowed deceased stallions or stallions with decreased fertility to continue breeding.”
ICSI was a reasonably uncommon procedure due to the expense and low success rates. However, it is gaining popularity among active show horses, high-value animals, and beloved animals where the owner wants to avoid the risks of pregnancy.
“ICSI is ideal for the active show mare whose owners don’t want her to be out of training long. We have mares come in for the ICSI procedure frequently, and they are here for 7-10 days for their egg retrieval, and then they can go right back to work.”
Gumz adds, “Another amazing advantage of ICSI is that it has become possible to breed a mare postmortem. Shortly after she has passed, you can remove the ovaries and send them to a lab to aspirate any eggs in hopes of carrying on her legacy.”
“I like that ICSI allows you to create multiple embryos in one process as opposed to breeding and flushing for embryo transfers each year – which isn’t that economical,” Gumz explains. “I had a mare generate seven frozen embryos through one egg retrieval procedure. Long-term, this was far more economical.”
Gumz emphasizes, “With the rapid increase in availability and demand for advanced breeding technology, the industry has experienced a major shortage in recipient mares. I’ve had mares ready for an embryo transfer, but we’ve been unable to arrange for a recipient mare cycling with her – which can be incredibly stressful, expensive, and cause you to miss cycles.”
“Using ICSI allows an opportunity to freeze the embryos, eliminating the pressure of syncing up with a recipe mare. Instead, you can thaw the embryo on the recipient’s natural cycle without manipulating it to align with the donor mare. Frozen embryos, like frozen semen, give you so many more options, allowing you to wait a season or years before transferring them to your recipient.”
While every lab and region differs, Gumz has found that a single round of ICSI generally costs around $5,000. “In my experience, your ICSI fees cover egg retrieval, shipping the eggs to a lab, fertilizing the eggs, and freezing the resulting embryos. Freezing charges are usually charged per resulting embryo – so the more embryos you create, the higher your freezing costs will be.”
Gumz notes, “The ICSI costs do not include your stud fee. However, many top stallions have special agreements for ICSI. Some will charge a nominal fee for the use of the sperm and then will charge their full fee when the embryo is transferred into a recipient mare and results in a pregnancy. If you plan to do ICSI, it is important to discuss that with the stallion’s breeding manager.”
Looking Into the Future
Gumz believes that advanced breeding procedures will only become more popular with time. She already sees the potential for advanced testing options on the horizon.
“The science is there to allow for gender and genetic testing of embryos. Now, I’m hesitant to manipulate the embryo too much because they are fragile, and you don’t want to do anything to impact their viability.
However, as technology advances, I see the testing processes becoming less invasive, and you could test an ICSI embryo for genetic diseases, gender, and even color genes before transferring it.”
She chuckles, “Labs have been sexing bull semen for many years, but they’ve had less success with horse semen because it is more fragile – leave it to horses to be more difficult.”
“I’ve had many breeders express they are hoping for a foal of a particular gender. If the science advances for the reliable sexing of horse semen, I anticipate that becoming a popular option down the road.”
Ultimately, with the increased availability of more cost-effective advanced reproductive technology, there will be more opportunities to breed proven lines, increase genetic diversity, and hopefully decrease genetic diseases.
About the Author: Megan Rechberg is a World Champion pleasure horse enthusiast who works as a full-time mom, part-time litigation attorney, and owner/operator of Bred N Butter Equine Management – a company that focuses on social media management for stallions, consulting, and sales and breeding contracts. She currently shows her APHA filly SmoreThanA PrettyFace under the guidance of Double A Performance Horses.
Photos courtesy of Viagen Pets & Equine
