What is the difference between embryo transfer and ICSI?

Embryo transfer breeds the donor mare with fresh or frozen semen, then flushes the embryo about a week after ovulation and transfers it into a recipient mare who carries the foal. ICSI works further upstream: oocytes are retrieved directly from the mare’s ovaries, a single sperm is injected into each oocyte in the laboratory, and resulting embryos are transferred or frozen. ET is the workhorse for fertile mares; ICSI is the tool when the mare, the semen, or the logistics rule conventional breeding out.

Can my mare keep competing while producing foals?

Yes — that is the core promise of embryo transfer. The donor mare is bred and flushed, the recipient carries the pregnancy, and the donor returns to training within days. Most major breed registries, including AQHA, register multiple foals per mare per year produced this way, which is how elite show mares now build produce records during their performance careers.

What does embryo transfer or ICSI cost?

Costs vary by clinic, region, and how cooperative the mare is, but plan in thousands of dollars per pregnancy for ET — covering breeding management, flush, transfer, and recipient mare fees — and meaningfully more for ICSI, which adds oocyte retrieval and laboratory fertilization. The honest budgeting unit is cost per live foal, not per attempt, since neither technique guarantees a pregnancy on the first try. It is worth knowing that some mares produce a significant number of embryos in a single ICSI cycle, which can make ICSI more cost-effective than repeated flushing — but it is very mare-dependent and program-dependent, which is exactly where an advisory session earns its keep.

Is ICSI worth it for a mare with fertility problems?

Often, yes — it was largely built for exactly that mare. Because ICSI bypasses the uterus and requires only oocytes, mares who cannot conceive or carry conventionally can still produce foals. It is also the answer for a busy mare who needs to produce several foals across a show season without leaving competition. And as success rates have climbed over the last five years, ICSI is increasingly used on younger mares too — with very good outcomes and real longevity for the donor mare. The same math applies as everywhere in breeding: the mare’s genetic value has to justify the cost. ICSI multiplies a great mare; it cannot upgrade an average one.

Embryo Transfer and ICSI: A Mare Owner’s Guide

Twenty years ago, a great performance mare faced a choice: compete or produce. Today she can do both at once — and produce multiple foals a year while she does it. Embryo transfer and ICSI have quietly rebuilt the economics of the mare side of the industry, and understanding them is no longer optional for anyone breeding seriously. But the technology comes with its own decisions, costs, and failure modes, and the marketing rarely explains them.

The reproduction program at Solo Select Horses is among the largest in the world — built around more than 2,500 recipient mares — and the advisors who help oversee and execute it have managed reproduction at every scale. Matt Witman oversees the full program — embryo transfer, ICSI, and mare-cycle management — after running breeding logistics for some of the most heavily booked stallions in the sport, including Corona Cartel, Valiant Hero, and PYC Paint Your Wagon, where timing and semen management decide outcomes at volume. Alongside him, Don Ham — who managed sires including Smart Little Lena and High Brow Cat across three decades — and Ty Smith help guide mare owners through the decisions that matter most: which stallion, which reproduction technique fits the mare, and how to build a season around them. Here is the guide they wish every mare owner had read before breeding season.

Embryo transfer: the workhorse

Embryo transfer (ET) is conceptually simple. The donor mare — your mare — is bred at the right point in her cycle with fresh or frozen semen; we don’t breed conventionally. About seven to eight days after ovulation, before the embryo implants, the uterus is flushed and the embryo recovered. It is then transferred into a recipient mare whose cycle has been synchronized to match, and she carries the pregnancy, foals out, and raises the foal.

What this buys you:

A competing mare keeps competing — she is out of training for days, not a year
Multiple foals per year from one mare, where registries allow it (AQHA does)
Insurance against age — banking embryos from a mare’s best years, before fertility declines
Protection of the mare herself when a pregnancy would carry health risk
Freezing embryos — banking them from young or older mares for future use

The requirements are real, too: ET works best on a reproductively healthy donor, demands precise cycle management and timing, and stands or falls on the recipient herd.

ICSI: the precision tool

Intracytoplasmic sperm injection (ICSI) moves the work upstream and into the laboratory. Oocytes are retrieved directly from the mare’s ovaries — a sedated, ultrasound-guided procedure called aspiration; show mares are often back at the trainer’s the same day — then matured in the lab, where each is fertilized by injecting a single sperm cell. Resulting embryos are reported over the next twelve days or so, as the ICSI cycle takes shape, and are transferred into recipients or frozen for later.

Because ICSI needs only oocytes and almost no semen, it is the answer when conventional breeding is ruled out:

Subfertile mares — uterine problems, chronic infections, “ICSI-only” mares who cannot be flushed at all
Precious semen — a few straws of a deceased or limited stallion can produce many ICSI attempts, where one straw is one conventional breeding
Frozen semen that performs poorly in the uterus but fine under the microscope
Show-career and out-of-season production — aspiration runs year-round, every three to seven weeks if needed

On the costs, Melanie Smith is concrete:

“I always say to ICSI or aspirate your mare, win, lose, or draw, you need to budget about $2,500 to $3,000. That’s the base cost to aspirate them, do the ICSI process in the lab, the mare management, all of that.”

Melanie Smith, The Business of Horses, Ep. 12: Breeding Logistics 101

Embryos add roughly $1,000 apiece, and a realistic yield is two to three per cycle — though a strong mare can throw several in a single cycle, which is part of why ICSI sometimes pencils out better than repeated flushing. Either way the decision is economic as much as veterinary: the mare’s genetic value has to carry the math.

The recipient mare: the variable nobody markets

Every transferred embryo spends eleven months in, and a half-year nursing on, a mare you did not choose for her pedigree. The recipient is the environment — her health, her size, her milk, her temperament all leave fingerprints on the foal. Good operations buy recips in the off-season on age, temperament, and reproductive conformation, quarantine them into a closed herd, and manage above all for low stress. The other half is depth, as recip-farm manager Kim explains:

“We’re not just dumping your embryo in a mare because we don’t have anything else that’s going to fit. We purposely set up more mares than we need on every day so that we can juggle that and we can still put your embryo in the best mare possible.”

Kim, recipient mare farm manager, The Business of Horses, Ep. 16: Inside Solo Select’s 2,500-Mare Recipient Mare Operation

That depth — fifteen mares set up to use ten — is why large operations post pregnancy rates that small ad-hoc arrangements cannot match. When you compare providers, ask about the recip herd first: where the mares come from, whether pregnancies stay on progesterone support through 150 days, and whether a live foal guarantee backs mares that stay through foaling.

The calendar: breeding season is won by planning

The most common — and most avoidable — failure in advanced reproduction is starting late. It does not matter whether you want early foals or you plan to breed in July; what matters is that the plan is made before you need it. The sequence that works: stallion decisions and contracts settled early; the mare’s full reproductive workup before the season; semen logistics confirmed — availability, shipping days, frozen inventory — before the first cycle, not during it; and a written plan for how many foals, by which sires, with which technique. Two things sink more breedings than almost anything else. First, do not call for frozen semen the day you need it — as Melanie Smith warns, “all of a sudden in March everybody remembers it’s breeding season and they all call at one time and need frozen semen tomorrow,” and a busy stallion station fields 100 to 150 semen orders a day. Second, keep your fresh semen collection calendar somewhere your vet can get to it easily. Mares do not read calendars; the programs that get the timing right are the ones that planned ahead. Our breeding season checklist walks the full sequence.

The strategy question above all of it

Technology answers how. It cannot answer whether — and that is the expensive question. Multiplying a mare multiplies whatever she is: five foals from the right mare build a program, and five foals from the wrong mare quintuple a mistake. Before the first flush, the honest work is deciding which mares deserve multiplication — produce record, family, physical, market. That is a strategy session, not a vet visit, and it is exactly what an hour with an advisor is built to settle before the season starts.