Stallion Showcase 2023: ICSI gives horse owners another option to carry on valuable genetics
When A Smooth Guy broke his leg and had to be euthanized, Myers Quarter Horses didn’t have much of his semen stored.
But with modern technology, the sire of offspring that have earned more than $2 million could sire as many as 200 more foals.
The process is called intracytoplasmic sperm injection (ICSI) and it has a variety of applications, said Dr. Jennifer Hatzel, assistant professor in the department of clinical sciences at Colorado State University.
The process is expensive and not guaranteed to be successful, but in cases where other reproductive assistance techniques aren’t possible, ICSI gives mare owners and stallion owners an option to carry on genetics that otherwise may be limited.
Myers sent A Smooth Guy’s testicles, postmortem, to Texas, where they were able to retrieve semen for future breedings. That process is called gamete rescue, and extends the fertility of stallions beyond their own lifespan, or even their collected semen.
ICSI uses oocytes (unfertilized eggs) from a mare, and injects a single sperm into a single egg. The fertilized oocyte is placed in an incubator for several days, then put into a recipient mare or the donor mare, or frozen for later use.
One of the major benefits, as Myers have seen, is that it uses a single sperm. Unlike artificial insemination (AI), which uses thousands of sperm in each straw, and takes place inside the mare, ICSI can make limited sperm resources last a lot longer.
Similarly, the process can be used to harvest oocytes from mares that are unable to be bred conventionally, or even flushed for embryo transfer. It can also be used to harvest eggs from mares postmortem, to carry on genes that way, Hatzel said. The unfertilized eggs can’t be frozen and stored, but fertilized eggs can, so ICSI can provide an option for saving those eggs, though mating decisions have to be made quickly in that scenario.
“I would say it started out being a solution that was sought after for mares that were suffering from infertility. Older mares, mares that had reproductive problems, could no longer carry a foal to term, and just as importantly, could no longer donate an embryo,” Hatzel said. “That’s where we’ve really found that ICSI comes in handy.”
While it offers that solution for mares, the horse industry has driven it more from the stallion side.
“People are choosing to use this procedure in young, healthy mares that could feasibly have healthy offspring, but because they’ve chosen a stallion that is either deceased or has a limited amount of frozen sperm available, this is the viable option,” Hatzel said.
Normally one straw is used for AI, but the same straw can be cut 10 to 15 times for ICSI use.
Though the cost is limiting, those who are making high-end matings are using it even when circumstances don’t dictate the necessity, Hatzel said. One session of ovum pick up (OPU) and ICSI could produce two to three embryos, instead of the usual one for embryo transfer.
But there are drawbacks, she said. “I think it works really well in some situations. I don’t know that it should be the go-to for every mare and every situation. It’s invasive–it uses a needle to go directly into the abdomen, so there’s an increased amount of risk compared to embryo flushing. It’s not a benign procedure to take lightly.”
Myers, who has used it on some of his own mares, in addition to providing semen to outside mares for ICSI, said the cost is generally around $8,500 to $10,000 for the procedure, without the cost of the semen. A Smooth Guy’s semen for ICSI is listed at $3,500. “The best case scenario is you get multiple babies out of one ICSI session,” Myers said. “If you get multiple pregnancies, then that cheapens your overall deal. But they don’t all work. Sometimes you pay quite a bit and don’t get anything. Then you’ve got to put that on the cost of your next one.”
But for the right mare and the right stallion in the right situation, there’s a high reward for the high risk. It can be used to extend the breeding season, in addition to addressing fertility issues in both mares and stallions.
“Anytime you start getting that specific and so scientifically technical, everything has to line up,” Myers said. “The stars gotta line up. It’s not an easy process when you start doing that kind of stuff.”