Warmblood Breeding Stud - Frozen Semen - Warmblood Horses - International sires
Warmblood Breeding Stud - Frozen Semen - Warmblood Horses - International sires
Warmblood Breeding Stud - Frozen Semen - Warmblood Horses - International sires

Artificial Insemination


AI is now a common procedure in equine reproduction. Australian horse breeders can now access semen from all over the country, as well as internationally. AI can be performed using fresh, chilled or frozen semen.

Prior to insemination your mare will undergo a reproductive examination and a uterine swab. This swab needs to be performed while the mare is in season, and will determine whether your mare’s uterus is free from infection. If your mare is not in season, we can either wait for a natural cycle to occur, or we can induce them to come in to season with a prostaglandin (Pg) injection. At Oakford Equine Hospital we have a resident teaser stallion which can help to determine if your mare is in season. “Teasing up” with our stallion is a free service, but please call to let us know you are coming.

When your mare is in season she will require a number of follicle tests to determine when is the optimal time for insemination. As mentioned previously, a mare is in season for approximately five days, with ovulation occurring towards the end of this period. Follicle tests involve the monitoring of follicle size and characteristic uterine changes via rectal examination with ultrasound. Mares being bred with frozen semen will usually require more intensive monitoring than those being bred with fresh or chilled semen.

Once a follicle reaches an appropriate size (usually 35mm, but this depends on the size of the mare) your mare will usually be given an injection of deslorelin, a hormone which induces ovulation. Ovulation will typically occur 36-48 hours post injection.

Post insemination your mare will require a further follicle test to ensure that ovulation has occurred and determine whether there is any pooling of fluid in the uterus. Any pooling of fluid is usually as a result of an inflammatory response by the uterus to the semen or semen extender. This can be dealt with using injections of oxytocin, and saline flushes. The first pregnancy test can then be performed at 14-16 days post ovulation.

Fresh Semen

Fresh semen only survives for a very short time outside the mare’s reproductive tract so must be inseminated immediately following collection. Once inside the mare it can last for up to 72-96 hours. Fresh semen AI has a very high success rate, but can only be performed when the mare and the stallion are in very close proximity to each other.

Chilled Semen

Chilled semen is viable for approximately 48 hours post collection, which makes it ideal for stallions anywhere within Australia. Success rates with chilled semen are generally much higher than with frozen semen.

Frozen Semen

Semen frozen in liquid nitrogen has an indefinite lifespan. This means that semen can be shipped to Australia from stallions internationally, and stored until required. It also allows semen from deceased stallions to be available.

The disadvantages of frozen semen are that success rates are much less than those using chilled or fresh semen. This is because the freezing and thawing process is damaging to the sperm. Once thawed, frozen semen usually has a lower motility, and the sperm do not live for long (usually less than 6 hours). Therefore it is extremely important that insemination is timed very close to ovulation. This requires the use of ovulating agents (deslorelin) and multiple follicle tests, as often as every three hours when the mare is close to ovulating.

When breeding with frozen semen it is important that the mare is easy to breed. Successful pregnancies with frozen semen are difficult enough without adding a problem mare into the mix. Ideally the mare should have already been successfully bred with fresh or chilled semen and delivered a healthy foal at term.

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