Breeding With Science

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.