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Frequently Asked Questions

Breeding

     

Q3)  Is it possible to control a mare's cycle, can I decide when she will ovulate?

Yes, there are several ways to not only bring your mare into heat earlier in the season but also to control when she will ovulate. There are basically two methods, one is through the use of environmental stimuli and the other is through the use of hormonal drugs and implants. Although there are arguments against both by those who feel it is important to let nature run its course, many breeders have found that by using one or both methods their breeding productivity can be noticeably increased. And since there have not been any recorded negative side effects to either mare or foal these methods are fast becoming more and more popular.

In the wild, mares usually do not become truly fertile until May or June. This is when the conditions are ideal because food is in good supply and the longer daylight hours provide for increased activity and movement. This is a time when horses can use their energy for other things rather than survival, which is their main focus during the winter months. Breeding at this time also insures that foals will be born in mild weather the following year.

If we can trick the mare's body into believing that May/June has arrived in the middle of February we will have access to her optimum fertility much earlier in the year. As mentioned before we can achieve this through environmental stimuli. This includes installing lights in her stall that will come on in the morning to simulate an earlier dawn and stay on longer at night to simulate a later sunset. The mare's feed can also be cut back severely in November and then slowly increased very early in the year, this simulates the "starvation" of winter being replaced by the "bounty" of late spring.

Controlling when the mare actually ovulates can be much trickier process and normally includes using hormone stimulators. One of these hormone stimulators is called Ovuplant. It is a small implant that can be inserted under the skin and releases a chemical called deslorelin which then stimulates the mare's hormones to induce ovulation. Within 48 hours of the implant the mare should ovulate. Although it seems like a great idea there is a catch. The American Association of Equine Practitioners has announced that there was a significant percentage of mares who had received Ovuplant inserts but did not conceive on the ensuing ovulation that were not able to conceive for the rest of the season. For this reason it has been suggested that if an Ovuplant is used that it is removed immediately after it is determined that the mare did not conceive.

Another option is an injection of a hormone called Human Chorionic Gonadotropin that will stimulate a mature follicle to ovulate in 24 to 48 hours with an average of 36 hours. HCG is a hormone produced in the human body by the placenta of a pregnant woman. It is present in the urine and is what causes a pregnancy test to show a positive result. Normally the injection is given on the same day as insemination or live cover. An alternative method is to inseminate/cover the mare, then give the HCG injection, followed by another insemination/cover 12 hours later.

Other hormones used to manipulate the mare's estrous cycle but not necessarily to induce an ovulation are prostaglandin, progesterone and estrogen. For example prostaglandin can be used to shorten a mare's estrous cycle. Or perhaps you have 2 mares that need to be inseminated using a single ejaculate. By using progesterone, estrogen and HCG  it is possible to synchronize both mare's ovulation to within just a couple of days of one another. Alternatively, progesterone can also be used to prevent the loss of a pregnancy and estrogen can be used to delay ovulation in the foal heat. This ability to restrict ovulation to a relatively predictable window of time has allowed many breeders to have more successful conception rates.

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