- Breeding
- OmegaTri & the Equine - Reducing Inflammation, Restoring Balance
- Horse Breeding, Part 3: Birth and Care of a Foal
- What do do when the Panic is On to keep our Horses Safe!
- Buying a Horse
- How to Buy Horses: A Step by Step Process
- When Dealing With Horses Get It in Writing - Sign Up for May 16 FREE Webinar
- Rocky Mountain Horses
- General Horse Articles
- How to Care for Your Horse in the Winter
- The Winning Horse
- Fueling the Motor – Energy Sources for Horses
- Horse Feeding
- Equine Experts Send Us Your Best Tip - Win $750 Worth of KAM’s Healthy Horse Products and More
- Cookies With a Clue For Your Horse
- The Scoop on Protein
- Horse Grooming
- Equine Experts Send Us Your Best Tip - Win $750 Worth of KAM’s Healthy Horse Products and More
- Relive Southern Eighths/Nikon Three-Day on YouTube
- Mane Saving Ideas
- Horse Health Issues
- The Winning Horse
- It’s Getting Cold Out! What to Do With Your Horse
- You’ve Got the Right Feed, Now What?: Proper Feeding Practices
- Horse Training
- Mythunderstandings About Riding the Trot
- Why Making a Rope Halter Isn't as Easy as They Say
- Training Mythunderstandings: More Early Lessons for the Green Horse
- Horses & History
- Equine Experts Send Us Your Best Tip - Win $750 Worth of KAM’s Healthy Horse Products and More
- What do do when the Panic is On to keep our Horses Safe!
- A Brief History of Draft Horses
- Horses & Sports
- Submit Your Grant Proposal To USA Equestrian Trust
- Relive Southern Eighths/Nikon Three-Day on YouTube
- In Defense of Horses in Sport
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Horse Breeding, Part 1: The Estrous Cycle
05/26/2008 So you are interested in breeding horses. Horse breeding can be a profitable and very fulfilling task, if done correctly. But before you go into the breeding process, it is important to take a look at the basics behind it.
So you are interested in breeding horses. Horse breeding can be a profitable and very fulfilling task, if done correctly. But before you go into the breeding process, it is important to take a look at the basics behind it. This three-part series will give you a basic understanding of the horse reproductive process.
To begin, the estrous cycle – also spelled “oestrous” – is the cycle that physically prepares a mare for conception. It controls when a mare is sexually receptive to a stallion. Usually, this happens during the spring and summer months, though it is not out of the ordinary for a mare to go through this cycle as late as fall. This cycle’s length averages 21 days, give or take a day. Towards the end of the cycle, the mare begins to go into anestrous, where she is not sexually receptive to males. This cycle keeps through the winter months, preventing a mare from being impregnated during the tougher months of the year.
The estrous cycle goes through two phases. The first is the Follicular phase, which lasts anywhere from five days to a week. This phase is when the mare is the most sexually receptive to the stallion. Estrogen is secreted and ovulation occurs during the final day or two of this phase. The second phase is the Luteal phase, which lasts around two weeks. This phase is when progesterone is secreted. The mare is not sexually receptive to the stallion during this phase.
From a physical standpoint, the mare’s body goes through several changes during this process: muscular tone increases in the uterus, and the vagina and cervix both relax. This prepares the mare for conception. During the Luteal cycle, the uterus becomes flaccid, and the vagina and cervix close. These changes then prevent the mare from being impregnated.
Our next section will look at the breeding and gestation period, including caring for the pregnant mare.

