Equine Artificial Insemination

Artificial insemination involves collecting semen from a stallion commonly with the use of an “artificial vagina” (AV). The semen is then processed and either transferred into the mares uterus or stored using the appropriate techniques and transported accordingly to be inseminated into a mare. 

Fresh semen should be used very shortly after collection and transferred directly into the mare’s uterus 12 to 24 hours before ovulation. This will have been organised based on veterinary ultrasound scans to determine a viable follicle and the use of reproductive drugs to ensure that the mare ovulates within the appropriate time after insemination. 

+ The benefits of fresh semen is that there is little to no processing of the semen involved and it has the highest fertility rates. It is therefore is recommended for sub-fertile or difficult mares. 

- The disadvantages may be that the semen has a short lifespan once collected and the more time that passes, the more the semen drops in quality. This requires the mare and stallion to be in close proximity and therefore is limited to the stallions availability.

Chilled semen involves collecting semen from the stallion, evaluating the sperm and extending the sample accordingly to create multiple doses. This is then packaged ready to transport. The chilled semen can be transported for up to 48h before the quality starts to decrease. It is also transferred into the mare’s uterus 12 to 24 hours before ovulation. This will have been organised based on veterinary ultrasound scans to determine a viable follicle and the use of reproductive drugs to ensure that the mare ovulates within the appropriate time period after insemination.

+ Chilled semen is comparable to fresh semen in regards to fertility rates, and it can travel for up to 48 hours whilst maintaining a good motility if processed correctly. This means that you can time it around the availability of the stallion and use stallions further afield (even interstate!). Multiple doses can also be created from one collection so the opportunity to inseminate multiple times or multiple mares can be achieved. 

- The disadvantages are mainly due to delays with courier services and delivery. If this does happen then there is a risk that that the mare may ovulate before the semen arrives. It also incurs additional costs with shipping fees.

Frozen semen is processed by extending the semen collected from the stallion, it is then put into straws and stored in liquid nitrogen at -196°C . This can be kept indefinitely if correct storage is maintained. Each stallion may have a different number of straws per dose because this has been calculated to contain the optimum number of sperm to achieve a pregnancy.

Here at Woodgrange Equine Hospital, we prefer to use a deep horn insemination technique to get the semen as close as possible to the ovulating follicle. Frozen semen has a shorter lifespan within the mare (approximately 6 hours) and therefore insemination close to ovulation is essential. Therefore we opt to scan the mare every 6 hours once she has been programmed to ovulate and inseminate either at the time of ovulation/immediately post ovulation to ensure the best chance of success.

+ Advantages of frozen semen are that it can be ordered well in advance prior to your mare being ready for insemination and can be shipped worldwide. Because it can be stored indefinitely, it gives the opportunity to use semen from deceased stallions to continue their lines. The stallion’s availability does not cause a problem. 

- The disadvantages are that it may be considered less preferable to chilled semen due to lower fertility rates. However with advances in technology this has decreased with comparable results. The semen once thawed has a very short lifespan once inside the mare and must be inseminated within 6 hours of ovulation and most preferable as close to ovulation as possible. This requires a lot more intensive veterinary scans with an experienced veterinarian well practiced in using frozen semen. The veterinary practice must also have storage facilities to keep the semen. 

Upon your mare’s arrival, a thorough reproductive soundness examination will be performed and it will be identified where she is in her cycle. Regular ultrasound examinations of your mare’s uterus and ovaries are required to determine the most ideal time for insemination dependent on the type of semen being used. When there is a dominant follicle that reaches >35mm in size, she will then receive appropriate reproductive medications to program her for ovulation.

The fresh or chilled semen will be organised by the owner for an insemination 12 to 24 hours before ovulation. Frozen semen will need to be already available and should be shipped to the veterinary hospital before or on your mares arrival. This will need to be inseminated as close to ovulation as possible (within 6 hours of ovulation). Therefore, your mare will be scanned closely at our hospital overnight. All semen is analysed post insemination under the microscope to examine the motility and give us an indicator of its quality.

An ovulation scan is performed the following day to check your mare has ovulated appropriately and that there is no fluid or inflammation. It may be decided to flush your mare with sterile saline to ensure any excess semen or inflammatory fluid is removed for a happy uterine environment to accept the embryo when it comes down the fallopian tube into the uterus at day 6 post ovulation. 

If everything looks good on the ovulation scan then your mare will then be scanned at 14 days to check for a pregnancy and twins. The heart beat scan is then performed at day 28 and a final 45 day scan to ensure a healthy foetus. 

Your mare is welcome to stay with us in our paddocks at any point to make it easier for you throughout the process.