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ARTIFICIAL INSEMINATION 101
By Kathy Grimes DVM
The New Year is upon us, which means breeding season is right around the corner. With winter rodeos, and the start of the futurity season, we barrel racers will be busy, busy, busy over the next few months. If you haven’t chosen a stallion to breed to your mares yet, start doing your homework and put together your short list now. There are a multitude of things to consider when it comes to breeding – not only the form and function of the selected stallion’s physical and mental attributes but how they will cross with your mare. One decision you will need to make is how you will breed your mare. Some stallion owners only allow for live cover, while others will ship cooled or frozen semen. For shipped semen, artificial insemination comes into play. The process is quite simple, and allows a breeder with a mare in California to breed to a stallion in Florida without having to haul horses across the country. That said, as a mare owner, your concerns about shipped semen and artificial insemination differ somewhat from the perspective of the stallion owner. In this article, I will discuss breeding with artificial insemination and provide some insight for mare owners who are considering breeding their mare.
As a mare owner looking to breed, December and January are exciting times. The new stallion incentive auction catalogs are out and stallion advertising is everywhere. These catalogs are like Christmas wish catalogs for barrel horse breeders. It is always fun and exciting to look at all the available stallions and be able to choose the one that best complements your mare’s assets and deficiencies. But don’t leave your wits in the wish list, folks. Before you purchase a breeding, do your homework. It is not only about the stallion, but the stallion owner / breeder and their business methods as well. Review the breeding contract to be sure you understand all the requirements and availability of shipped semen and expenses. Don’t be afraid to call and talk to the stallion manager about their collection methods and shipping techniques to help ensure success. You should use a qualified veterinarian to perform the insemination – call your vet if you have questions as well. You will also need to provide the vet with a copy of the stallion contract. Your veterinarian may also have valuable insight for you on perspective stallions from past experience with the stallions shipping motility and success rates; as well as interactions with the stallion manager(s).
First and foremost, you need to understand that the process of artificial insemination isn’t something that can be done at the drop of a hat. If you are considering artificial insemination, youshould discuss scheduling and other concerns with your veterinarian early in the process. Your veterinarian will need to ultrasound the mare repeatedly during her heat cycle right up until the semen arrives. Many breeding farms will collect the stallion on a Monday, Wednesday, Friday schedule or an every-other-day schedule and ship with an overnight carrier. To help increase success rates, it is a good idea to track your mare’s cycles through the month prior to breeding.
Mares are “long day” breeders, meaning they need 16 hours of daylight to start cycling on a regular basis. Depending on where you live, this generally means most mares don’t normally begin to cycle consistently until April and will continue through September. If you want an earlier foal you can trick Mother Nature by putting your mare under lights starting December 1st. This should trigger the mare’s natural response to the longer days and she should start cycling in mid-February. The idea is to provide continuous lighting with lumens high enough to trigger the normal breeding cycle. The lighting should be bright enough that you can comfortably read a newspaper in every corner of the stall. The best way to do this is to stall the mare under lights which are timer controlled to allow for a full sixteen hours of light. Make sure the mare cannot put her head outside of the stall to be in the dark. If your mares are paddocked or on pasture, you will need to bring them in before dusk and get them under the lights. It is important to turn the lights off, or schedule your timers so that the mare can get 8 hours of good rest as well. If you have multiple mares you can have large paddocks with stadium-type lighting that can be automatically turned off at the appropriate time.
Whether you use artificial lighting or wait for Mother Nature to do her thing you need to keep in mind that mares go through a “transitional” heat cycle as they transition between anestrus (not cycling) and estrus (cycling). These transitional heat cycles can be unpredictable and frustrating – many times they last longer than normal and the mare doesn’t always have a proper ovulation. I generally advise clients not to breed during the transitional cycle if they want to increase odds of pregnancy with the first shipment of semen.
Mares will typically be in heat for five to seven days; longer in the early spring and shorter in the late summer into fall. It is typically fifteen to sixteen days between heat cycles. A mare’s estrogen level goes up at the end of her heat cycle and that is when she shows active signs of being in heat. Some mare owners will see the mare teasing and assume she is just starting her heat cycle. Unfortunately, if you wait this long, by the time the mare gets to the vet it may be too late to get the semen ordered in time for a successful breeding on that cycle. This is why, if you want to be successful, it is so important to track the mare’s cycle the month prior if possible.
With some mares it may be difficult to tell when they are cycling. In these cases, your veterinarian can use hormones to assist in bringing them into heat. Timing is extremely important when it comes to artificial insemination. A mare’s follicle (structure that produces the egg) will grow between 3-5mm a day during her heat cycle. A typical mare will ovulate when their follicles are in the 40mm range. Once the follicle gets to 35mm or greater hormones can be used to trigger ovulation. Ovulation time is important when using shipped semen because the mare needs to ovulate within 48 hours of the semen being collected to increase the odds of success. Pregnancy success rates significantly decrease when a mare is inseminated greater than 6-8 hours after ovulation. Daily ultrasounds and accurate record keeping are important tools to ensure success.
Ideally you would begin ultrasounds at the begin-ning of her heat cycle, as soon as she shows signs of heat; 15 days from her last heat cycle, or 3-4 days after using hormones to bring her into heat. Daily ultrasounds help monitor the growth of her follicle and coordinate when her follicle will be the proper size to order the semen – taking into consideration the stallion manager’s collection / shipping schedule. So let’s say on a Tuesday your mare has a 35mm follicle and is showing signs of heat and other appropriate ultrasonographic criteria. Your stallion’s breeding manager is on a M/W/F collection and shipping schedule. After determining your mare is ready by ultrasound, you would contact the stallion manager to order the semen for a Wednesday collection and shipment. In this scenario, the semen would arrive on Thursday and be inseminated into the mare immediately. With the assistance of the hormone injection, the mare should ovulate at some point after insemination and before the end of the day on Friday. This is a perfect scenario and it’s great when all goes according to plan. Unfortunately, it doesn’t always happen that way.
In my practice, I’ve seen just about every imaginable thing happen to interfere with a perfect breeding … everything from the mare not responding to the hormones, to a misplaced or mis-sorted semen container spending an extra day or two in a bulk-shipping center in Kansas City. If the semen is late (after the mare ovulates), you’re out of luck. If the mare doesn’t cooperate and ovulates later than expected you may still have a shot because some stallions’ semen will remain active longer than the typical 48-72 hours. You should also remember that you are likely not the only one in line for semen on any given day. If there are more orders than semen, you might do all the work to prepare and then find out you can’t get semen. The point being that sometimes stuff happens. In order to best avoid these issues and avoid additional costs of multiple shipments and vet fees, proper mare management pre-cycle and during the heat cycle is important. With collection and shipping costs running anywhere from $150.00-$350.00 per shipment plus additional veterinary fees, breeding can get expensive fast if you aren’t organized and don’t have a solid game plan.
The stallion manager faces a different set of concerns. There are collection issues, motility and fertility issues, and there is only so much semen to go around. If the stallion is standing at a breeding facility under the supervision of the stallion owner, there will be mares on the farm to breed as well as the semen that needs to be shipped out … priority will usually go to the farm’s mares. This is why preparation on the mare owner’s part and early communication between the mare owner, veteri-narian and stallion manager are key!
Depending on how fertile a stallion is, multiple “doses” of semen can be collected from one ejaculation. A set number of progressively motile sperm need to be inseminated in the mare to ensure the stallion’s part in a successful pregnancy. Because each ejaculation on any given day is different, it is important that the stallion manager has the proper equipment to count the sperm in a given collection to ensure that each shipment contains the proper amount of sperm. A densimeter (sperm counter) is an essential tool for the stallion manager. As a mare owner, you should inquire of the stallion manager what the stallion’s typical motility rates have been over the past year, and if they are using a densimeter to confirm sperm density with each collection.
Once the semen is collected and the sperm count and motility is checked; the semen is processed by add-ing an “extender” to help keep the semen alive. The extender also contains antibiotics to help prevent infection. The semen is then placed in a special shipping container that cools and keeps the semen at an appropriate temperature, and shipped overnight to the veterinarian. Albeit more expensive, counter to counter shipping through the airlines may also be an option if a mare is on the verge of ovulation and expedited shipping is necessary. The availability of this method of delivery is something you should discuss with the stallion manager when the breeding contract is signed.
Frozen semen is also an option, and in some cases, such as a deceased stallion, the only option. Using frozen semen in artificial insemination requires a more focused approach. Precise timing of the in-semination in relationship to the time of ovulation is important for successful breeding. The semen should be inseminated within a 12 hour window - 6 hours prior / 6 hours after ovulation. How well the stallion’s semen freezes will also be a factor in determining pregnancy success. Because use of frozen semen requires more work for the veterinarian, it typically is a more expensive option. Also, you should consider that frozen semen can have a slightly lower conception rate than cooled or fresh semen; possibly leading to multiple attempts at insemination which could increase costs.
It has been my experience that the more experienced and successful stallion managers or breeding facilities will go to great lengths to try to assure that they are shipping a good product to ensure good conception rates. A good manager will include sperm collection information, processing informa-tion, sperm count and motility information in each shipment, and they want to hear back from your veterinarian if there are any problems with the shipment. However, this is not always the case. It has been my experience some breeders have little experience in handling semen, and in some cases don’t seem to care as long as they are being paid the collection and shipping fees. In these cases, breeding can be a frustrating experience for the veterinarian as well as the mare owner. Avoiding this scenario is just one more reason to do your homework up front, and not be afraid to ask critical questions of your chosen stallion’s breeding manager and your veterinarian.
Artificial insemination is a wonderful asset to our breeding programs. Breeding a mare and anticipat-ing what the breeding will bring into the world is always exciting, but more goes into choosing a stallion for your mare than just the pretty factor. A stallion fee may seem like a bargain at $750.00, but if the stallion has poor motility and a low conception rate, and the stallion breeding manager doesn’t have the proper education, experience, and tools to address your concerns, that $750.00 investment could turn into a couple thousand dollars in collection/shipping fees and veterinarian costs in a hurry. Do your homework, educate yourself and prepare. Choose a solid stallion under the breeding management of a reputable breeder. Work closely with your veterinarian to get the bun in the oven, then spend the next eleven months daydreaming about the final result of your work … a beautiful, athletic, willing and good minded colt with rocket speed. Good luck with your breeding this spring!
Courtesy Kathy Grimes
© Reprint BHHLLC 2015