Breeding With Science

There can be many unknowns in the world of artificial insemination, but there are a few rules of thumb to ensure the best possible threat.

Breeding your mare via artificial insemination (AI) has many advantages. Chief among these is access to the best possible stallion—whether he’s across town or on the other side of the Atlantic—without traveling.

But AI has its downside, too, according to Paul Loomis, whose company, Select Breeders Service, freezes, stores and distributes semen from Hilltop Farm in Colora, Md. There are a number of things mare owners should know about the possible pitfalls, he says, before arranging to have a veterinarian insert a stallion’s semen into their mare’s uterus.

First, check with your breed registry to make sure they allow AI breedings. Most major registries do, including the American Quarter Horse Association, American Paint Horse Association, Appaloosa Horse Club and Arabian Horse Registry, as well as most warmblood breeds. However, the Jockey Club and some smaller registries—such as the American Shetland Pony Club—do not permit AI.

Even associations that permit AI often have restrictions. They may allow breeding with fresh semen, but not transported. Or they may allow cooled, but not frozen. They may also require special paperwork or the use of a registry-approved veterinarian to perform the procedure. Get all the details before shopping for semen.

Question the Quality

A critical point to consider with AI, says Loomis, is that there are no regulations. Stallion owners don’t have to meet standards of quality for their facilities, their methods—or their stallion’s semen. Of course, most good farms do strive to provide a high-quality product, but don’t assume that’s always the case. Instead, ask questions. “The more information you can get, the better,” says Loomis. “If a stallion owner just tells me that the stallion’s semen is fine or that it ships fine, I’d want more details.”

Specifically, ask about the motility and fertility rates for the type of semen you plan to order—fresh, cooled or frozen. (Remember, cautions Loomis, a stallion may be fertile with fresh semen, but infertile with cooled and/or frozen.)

Motility refers to sperm movement and provides an indication of the semen’s viability. For cooled semen, ask for motility values 24 hours and 48 hours after collection, which is how long cooled semen can normally last. For frozen semen, ask about post-thaw motility rates. The benchmark is 30 percent progressively motile: Cooled semen values should be higher than that at 24 hours, while post-thaw rates should be at least that.

Fertility, of course, relates to a stallion’s ability to impregnate a mare. “It’s the bottom line,” says Loomis. “Just because the sperm has good motility doesn’t mean it’s going to have good fertility.” Ask how many mares the stallion has bred using cooled (or frozen) semen and how many of them conceived. Most important, ask for the stallion’s per-cycle pregnancy rate (again, specifically for the type of semen you’ll be using). This number, explains Loomis, gives you an idea of how many mares conceived on the first cycle they were bred. And that directly affects your pocketbook.

For example, imagine two stallions, Ed and Ned, who each breed with 100 mares. Say that Ed has a 25 percent per-cycle conception rate and Ned has a 75 percent per-cycle rate. Both stallions may end up with the same number of foals born, but Ned impregnates more mares on their first cycle than does Ed. So, if you breed to Ned, you save money because you have a better chance of paying for just one round of shipping and vet costs to get the mare pregnant. With Ed’s low per-cycle rate, it will probably take two or three cycles before the mare conceives, which means you’ll pay collection, shipping and veterinary expenses two or three times.

Besides fertility and motility, also ask the stallion owner about these two factors:

•Antibiotics. Bacteria in semen can cause health problems such as endometriosis, especially in older mares, says Loomis. Make sure the farm uses an antibiotic in the semen extender, a nutrient medium that extends the useable life of the semen.

•Viruses. Viruses, such as EVA, can also be transmitted through semen. Loomis suggests that you ask about the viruses the stallion has been tested for and what the results are.

Get a Guarantee

Unfortunately, it might be difficult to get all this fertility information. “People often are either not forthcoming or they don’t have the data because they haven’t been keeping close records,” explains Loomis. Or, the stallion may never have been available through transported semen before, so data doesn’t yet exist.

If you can’t get the numbers you want, make sure the contract includes a conception guarantee—or walk away. In fact, says Loomis, even if the fertility numbers are available and look good, insist on some type of guarantee. “I wouldn’t sign a contract without one,” he states. “Otherwise, there is no risk to the stallion owner. You are taking it all.”

Loomis relates the story of a woman who imported semen from Germany as an example. Although there was no conception guarantee in the contract, the woman chose to take the risk anyway to breed her mares to a particular top stallion. Unfortunately, none of the mares conceived and, with no guarantee, she wound up out thousands of dollars.

Talk Cost

To calculate the total cost of live-cover breeding, you add transportation and mare board to the stud fee. For transported semen, you may have to add collection and shipping charges, instead. Ask what’s included in the advertised stud fee—and what other costs you’ll have to pay. For instance, says Loomis, “Some places charge a collection and handling fee each time you get a shipment, while others include the first two shipments in the stud fee.” Still others may include one shipment in the fee, but not subsequent shipments if the mare doesn’t take the first time.

This is important because a single collection fee could cost $125 to $300, while shipping costs might run $40 to $80 including an Equitainer for cooled semen or $80 to $100 for a nitrogen tank for frozen semen. (Importing semen may entail additional fees, tariffs and restrictions.) If you have to add these expenses to the stud fee, a seemingly low-priced stallion can suddenly cost as much as a higher-priced stallion whose fee includes those charges.

While you’re discussing fees, you might ask about discounts, as well. “Sometimes, if you have a high-quality mare, it may be in the stallion owner’s best interests to strike a deal,” says Loomis. “For instance, Hilltop offers a discount for certain grades of mares that have proven themselves as producers.”

Availability and Doses

Semen isn’t always ready and waiting to be shipped the moment you call for it. As Loomis explains, “Booking gives you access to the stallion during the breeding season—but there are often limitations on that access.” Many farms collect and ship semen only three days per week. It’s also possible that, if it was collected, the semen was used for on-farm breedings and none is left to ship. And, in other cases, the stallion may be unavailable because he’s competing.

This can be a problem because the ideal window for breeding your mare is relatively small: Ideally, insemination takes place from 12 hours before to six hours after ovulation, says Loomis. So, even a day’s delay in receiving the semen could mean the difference between conceiving and not conceiving, or between breeding this cycle versus waiting for the next. Again, ask questions and understand the protocol up front.

As you go through the contract, Loomis recommends that you also find out how many doses of semen you get with the breeding and how many doses come with the first shipment. In addition, he advises asking how many sperm are included in each dose. Make sure that you’re not getting mere leftovers of a collection already split between too many mares. Loomis notes that 500 million progressively motile sperm per cooled-semen dose is probably sufficient. In fact, he adds, a dose will typically have around 1 billion. With frozen semen, 200 million progressively motile sperm (post-thaw) is the norm.

Is AI Worth It?

Breeding by AI does have its fair share of caveats and complexities, but probably no more so than live-cover breeding. Certainly the difficulties haven’t dampened AI’s popularity. Although statistics are hard to come by, Loomis estimates that in the warmblood industry, where the technique has been accepted for roughly 15 years, some 75 to 80 percent of mares are bred using transported semen. In fact, the American Holsteiner Horse Association states that at least 99 percent of the breedings in its registry are done by AI. Similarly, the use of AI is increasing in the stock horse breeds, especially since the AQHA approved frozen semen last year.

In short, if you do choose AI, you’ll be in good company. And if you take some precautions, you’ll also raise the odds for a successful breeding experience.

AI Conception Rates

What type of conception rates should you expect with AI? That depends on the stallion’s fertility, the type of semen you’re using (fresh, cooled or frozen) and the expertise of the person performing the collection and insemination procedures.

In general, research has shown that fresh semen gives the best conception rates, says Paul Loomis. With cooled semen, rates drop about 10 percent, with another 10 percent drop for frozen. However, Loomis notes, in one study using 800 mares on three farms, using carefully monitored procedures, fertility rates for frozen semen were nearly identical to those for cooled semen.

In the real world, cooled semen conception rates often dip to frozen semen levels. Why? “There are a lot of inexperienced people shipping cooled semen who are doing a poor job or working without the proper equipment,” says Loomis. “On the other hand, frozen semen processing is very difficult and technical, so it’s typically prepared by big professional labs.”—SDW

Tips for Stallion Owners

As difficult as AI is for the mare owner, it isn’t any easier for the stallion owner. Here are tips for two common concerns.

The contract. Paul Loomis recommends that you, as the stallion owner, retain right of refusal. This allows you to deny breeding services to any mare. Perhaps a mare isn’t genetically suitable for your stallion and the resulting foal would be inferior, explains Loomis. Or maybe the mare is old or barren and getting her in-foal may require more work (and more semen shipments) than you’re willing to sacrifice.

The phantom. Where can you find a phantom mare to collect semen? If you’re the handyman type, you can build one. Jos Mottershead of Equine-Reproduction offers instructions online at Or you can buy one through breeder-supply services, such as Breeder’s Choice (940) 365-2231.—SDW






Oops! We could not locate your form.