Semen Considerations

The method by which semen is packaged and distributed will play a large factor in determining the total costs associated with getting your mare pregnant. The main “types” of semen distribution are via live cover, cool-shipped semen, or frozen semen.

When using live cover, the stallion will breed a mare naturally. This usually means the mare will have to travel to the stallion, so location may be a factor when selecting the stallion. Live cover can sometimes decrease your breeding expenses because the stallion will decide when your mare is ready to breed. However, have your veterinarian check the mare post-breeding to make ovulation occurred and that she is not retaining fluid, which will decrease her chances of conception. It is also recommended that mares only be bred live cover to stallions that require clean uterine cultures from all mares prior to breeding. That exam is best scheduled with your veterinarian on the cycle prior to getting your mare bred. This precaution will decrease the chances of sexually transmitted diseases and infections between the mares and stallions. 

Cool-shipped semen involves semen that has been collected from a stallion, filtered to remove the gel-fraction of the ejaculate and then extended with semen extender to provide extra nutrition to the sperm cells for longevity and also contains an antibiotic to kill any bacteria that may be in the semen. The extended semen is then cooled on ice and packaged in special containers. The semen can be then shipped on an airplane for same-day delivery or shipped via Fed-Ex for delivery the next day. The transported semen should be inseminated by your veterinarian as soon as it is received, as most sperm cells are only viable for about 48 hours. Most stallions only collect on certain days of the week (ex. Monday, Wednesday, Friday), so veterinary assistance will be required to line your mare up to be ready when semen is available. A benefit to cool-shipped semen is that stallion location is not a limiting factor, at least if he is in the contiguous United States or some parts of Canada.

Semen can also be frozen in liquid nitrogen and preserved indefinitely. After collection, the sperm cells are filtered and separated from the rest of the ejaculate using centrifugation. A special freezing extender is added to the sperm cells. The extender-cell mixture is then placed into small straws and frozen in liquid nitrogen using a particular method. The benefits of frozen semen include no limits to stallion location or adhering to a particular breeding schedule. Stallions can be located on different continents or even deceased and still be able to pass on their genetic material using frozen semen. Also, mares can be bred based on their own schedule, not on when the stallion is available. However, using frozen semen correctly is also more labor intensive and requires close monitoring by your veterinarian to get the semen inseminated at ovulation. Some mares are also more sensitive to the extenders used for freezing and may have an increased incidence of uterine reactions that can require more treatments and may lower conception rates. Proper storage and shipment of frozen semen is extremely important for maintaining viable semen long term . Using frozen semen sounds more complicated and intimidating, but its pregnancy rates are frequently comparable to the other semen types, depending on the stallion.

It is wise to keep in mind that no matter the semen type the fertility, quality, and motility of semen is completely dependent on the individual stallion, both in general and on a day to day basis. Age of the stallion, his diet and management, and especially the number of mares he is breeding in a season can greatly influence his semen quantity and quality. The “type” of semen distributed can also play a big factor. Some stallions cool or freeze better than others, and some stallions have better semen when it is extended versus when it is raw. However, the veterinarian in charge of managing that particular stallion will have experimented with different extenders and processing methods to maximize the quality of each sample that is shipped or frozen.