While both are tried and true breeding methods, is one more effective than the other? And which one is ideal for your mare?

Trying to decide whether to breed a broodmare by artificial insemination as opposed to live cover is a difficult decision and one that must take into account all of the intricacies involved in both options in order to increase the odds for a successful pregnancy.

Artificial insemination is by no means a new development in horse breeding. In fact, according to historians, the first documented use of artificial insemination in equines was in 1332 by an Arab chief who used the method to impregnate his prize mare.

Since then, scientists have been researching and improving the method. Veterinarians can now use ultrasound machines to track development of the follicle as well as evaluate the amount of uterine fluid to decide if the mare needs more treatment before or after she’s inseminated, thus improving chances for fertility.

The widespread use of prostaglandin, which helps bring mares into heat, as well as drugs used in cycling mares to induce ovulation, such as human chronic gonadotropin, have also boosted the success rate of artificial insemination. And experiments with different semen extenders and antibiotics contribute to improved semen quality and conception rates.

Collecting semen from the stallion is a fairly quick and easy process, assuming there are experienced handlers and well-maintained equipment. Once collected, the semen is filtered and then mixed with a milk-based extender to which an antibiotic is added. The semen is then prepared for either transport or storage.

But it is the timely ordering of the semen that proves to be the real trick for broodmare owners and veterinarians. With live cover, the stallion is usually within a day’s journey away, making timing the beginning of the “heat” cycle less of a problem.

Timing Is Everything

“Timing of shipping semen is a crux to the whole industry right now,” explained John Hurtgen, DVM, PhD, owner of Nandi Veterinary Associates (Pa.). “A problem vets tend to run into is that a lot of horse owners do something besides stick around home to breed their mare—they have other jobs. So the question becomes, ‘When is the vet supposed to examine the mare to place the semen order in a timely fashion?’ ”

Aside from the fact that many Americans who breed their mares have other jobs outside the horse industry, having a mare that does not follow the 21-day estrous cycle and five- to seven-day “in heat” cycle, makes the well-timed ordering of semen even more complex.

“Luckily, there are enough horses who read the book and stay in heat for five to seven days. With those types of mares, a vet can get away with examining after giving prostaglandin and can predict within a two-day range when the mare will ovulate and can therefore get the semen to arrive on time,” said Hurtgen.

“Where trouble arises is when a mare doesn’t do exactly what the book says,” Hurtgen continued. “There are so many pieces of this puzzle—you have a mare you think needs to be bred, then you need to find out the breeding farm rules to the stallion you’ve booked to. What days of the week is the stallion collected? What are the cut-off times for collection each day?”

Assuming you can take the time to meet the veterinarian each time he or she needs to come out and check your mare and presuming you can handle the stress of attempting to opportunely order the semen, is your mare a good candidate for artificial insemination?

“I believe anyone thinking about breeding their mare, especially if it’s the first time, needs to keep several things in mind,” emphasized Ellen Stephens, DVM, who owns and runs Laurel, Inc., an equine reproduction facility in Middleburg, Va.

“A mare that’s a good candidate is usually between 5 and 8 years of age, has a regular 21-day cycle as well as good conformation and a healthy body weight. Also, they need to be sure that they breed to a stallion that’s either smaller or similar in size to the maiden mare.”

The Live Cover Advantage

One way to avoid some of the headaches involved with artificial insemination is to breed by live cover, but then you must also take into consideration that it is significantly more dangerous to the stallion, the broodmare and handlers.

“One of the advantages of live cover is that all of the stallion’s sperm are deposited into the mare, so there are typically better conception rates, assuming the stallion is not bred more than twice a day, in which case the sperm counts would be lower,” said Stephens.

She added that people need to make sure that their mare’s “disposition is suited to live cover” and that “you go to a reputable breeding shed because you can run into trouble with inexperienced handlers.”

Hurtgen also agreed that live cover is a good option if there are no underlying reproduction problems in the mare.

“I think there should be equally high rates with either artificial insemination or live cover. I don’t think AI will step you up in terms of conception rates in part because the stallion is going to deliver semen directly to the uterus. Any time you collect, there are things you can do that can negatively impact semen quality, whereas a stallion does not have the opportunity to mishandle semen.

“But at the same time, there are some stallions that don’t cover mares well, or in a normal fashion,” he added. “For example, they ejaculate while they’re dismounting or the mare moves or outside contamination enters the mare during the cover. And then there are some stallions that are accustomed to being manipulated while others refuse guidance, so there are a lot of scenarios involved in live cover as well.”

Another problem with live cover is that, without knowing the stallion’s breeding pattern very well or without extra diagnostic tests, there is no way to be sure that he ejaculates into the mare.

“If the handler knows the stallion well, and has developed a pattern of how he breeds, then you may have a good idea,” said Hurtgen. “But a lot of stallions who live cover cover only a handful of mares a year, so your only basis of knowing success is whether the mare gets pregnant.”

Despite the risk involved, The Jockey Club still demands that all registered Thoroughbreds be bred through live cover. In fact, in The Jockey Club’s Principal Rules and Requirements of The American Stud Book, the rules explicitly state that artificial insemination is “expressly prohibited.”

“Some stallions just don’t belong in a cooled, shipped semen program and that’s not to mean that they can’t get a mare pregnant, but in this day and age, a mare owner usually has a certain level of expectation when a stallion is standing at stud to the public,” said Hurtgen.

“But on the receiving end, how many vets take a good look at the semen before they inseminate the mare?” he questioned. “I would say 50 percent never look at it before or after it’s put in the mare and instead rely on receiving a quality product. It’s hard to evaluate semen that is shipped to a private owner.

“A vet can put a sample in his pocket, and some can save it in a refrigerator to look at when they return to the clinic. If it’s good, then they know it was good when it was put in the mare, but if it’s bad, you have to consider how it was handled and put up a red flag so that next time you may have a look at the semen right out of the box. But this too can be difficult to do if you’re looking at various horses for general practice, which doesn’t fit nicely into evaluating semen.”    

Another viable option with artificial insemination is using fresh semen and inseminating the mare right after it is collected.

“If you have a local stallion and you can collect from the stallion and deposit the fresh semen in the mare the same day, the conception rate can actually be higher than live cover because the semen is cleaner. It’s also less traumatic on the mare, and the semen is inserted directly into the uterus,” enthused Stephens, a strong believer is using fresh semen to artificially inseminate.

What the debate over live cover versus artificial insemination really boils down to is knowing and understanding your mare, being aware of your own ability to dedicate time and effort to getting her pregnant and deciding upon what type of offspring you would like to produce.

“For certain mares, trying to breed with shipped, cooled semen can be extremely difficult, but for others, it’s like, ‘Oh, thank God that came along because my mare can stay in her own comfort zone.’ Everybody knows how breeding is supposed to get done, but applying it is not so easy. Getting good semen to the mare, whether it is through live cover or artificial insemination, is most important because the goal is to get the mare pregnant,” emphasized Hurtgen. “A mare’s reproductive cycle is much more variable than people’s time, so we need to stop trying to make the mare fit into our schedule.”