Our breeding advice begins by emphasizing the importance of starting with the right mare. This is indeed one of the keys to successful breeding. At the beginning of the breeding season, the mare should be in good physical condition, but not overweight, and should be promptly vaccinated, dewormed, dental, and reared. Mares' fertility decreases with age, and by the time mares reach their teenage years, they may have lower fertility than younger mares. Some signs or health conditions, such as obesity, equine metabolic syndrome, laminitis, and mid-pituitary dysfunction (PPID), may affect fertility or the mare's suitability for breeding. Before the breeding season, the breeding status of the mare should be checked by a veterinarian. This includes checking the mare's general condition and health, assessing body shape, and performing an ultrasound examination of the reproductive tract. If the mare has an abnormality or has a history of breeding problems, a uterine swab or biopsy may be performed at this time.
Natural mating with fertile mares usually results in a pregnancy rate of around 50-60% per cycle; Therefore, a fertile mare usually takes 1-2 cycles to conceive. In the case of natural mating, mares sometimes mate every other day during the high season. An ultrasound scan of the mare's ovaries can help optimize mating time, which can lead to higher pregnancy rates.
Artificial insemination (AI) refers to the introduction of ** previously collected from stallions into the uterus through the mare's cervix through a small straw. Artificial intelligence has several advantages over natural mating. The most important of these is to improve the safety of mares and stallions. In addition, there is the added benefit of being able to transport ** from the stallion to the mare over long distances. Due to the limited lifespan of **, artificial insemination requires an accurate time of ovulation.
Mare that show clear signs of season will usually have a scan as soon as they find the season arrives. For mares that do not show obvious signs of season, a scan can be done to see what stage of the cycle they are in. The veterinarian can inject prostaglandins (PG) simultaneously and then perform a scan 2-5 days later. Recently spawned mares are usually scanned 8-9 days after spawning, or PG 7 days after foals are in heat, and then scanned 2-3 days later. Ultrasound scans are then performed every 1-3 days until a sufficiently large follicle and a "normal uterus" are reached. Hormones (deslorelin or chorulon) are usually injected prior to mating or artificial insemination to further ensure and optimize the timing of ovulation.
Artificial insemination using fresh freezing** usually has a similar or slightly higher pregnancy rate than natural mating. When stored correctly, fresh frozen** typically remains viable for 24-30 hours during shipping, and then for a further 24-48 hours after fertilization. On the other hand, the pregnancy rate of freezing** is poorer and more variable, ranging from 0 to 70% (around 40% per cycle on average). For this reason, it is generally recommended to freeze** only for young mares or mares that have been shown to have good fertility. Frozen ** and newly ovulated oocytes (eggs) have a limited lifespan of 6-12 hours once fertilized, and the mare must be fertilized as close to the time of ovulation as possible (within 6 hours). As a result, mares need to undergo more intensive scans (sometimes every 3-6 hours) before ovulation.
Sometimes, the mare will have an ultrasound scan 6-24 hours after fertilization to ensure ovulation and to check for inflammation or infection. If there is inflammation or infection, it can be done about 5-6 days after ovulation before the fertilized embryo enters the uterus from the fallopian tubes**.
If embryo transfer (ET) is performed, the embryos are collected 7-8 days after ovulation. The collected embryos are then transferred directly to the recipient mare or frozen (vitrified) for later use.
At least three ultrasound scans of pregnancy should be performed; These tests are done regularly to monitor the progress of the pregnancy and minimize the risk of missing out on twin pregnancies. The first pregnancy scan should be done 15 days after ovulation, as this is the earliest time to reliably detect the pregnancy and diagnose and resolve the twins, if present. If the mare is not pregnant at this time, there may be follicles for the next "cycle". The next scan is usually done in about 25-28 days (where the heartbeat can be seen) and 45 days. Sometimes, if the mare has previously had two large follicles and is at risk of conceiving twins, an additional scan is done between the first and second scans.
The Veterinary Association has an experienced, knowledgeable and dedicated team who are more than happy to share their mare breeding advice and experience. We can take care of all your mare breeding needs, including breeding "soundness" checks, routine and non-routine procedures, management of problem mares, artificial insemination, embryo transfer, and embryo vitrification. We also have access to a number of local premium service facilities where your mare can enjoy a complete "start to finish" service.
If you need any breeding advice or have any questions about anything in this article, please feel free to contact us and we will be more than happy to assist you.