The benefits of using frozen semen when breeding a mare are numerous. Cryopreservation (freezing) allows long-term sperm storage, which in turn allows a breeder to but and store semen from a stallion of interest and save it for the right mare in the future. The ability to import frozen semen from other countries allows breeders access to quality stallions all over the world. And storing frozen semen gives mare owners the option to breed to stallions that have died, have been castrated or are actively competing and not available for collection.
Pregnancy rates achieved with frozen semen vary, but they average between 30-60% per estrous cycle. While it might take more than one cycle to achieve a pregnancy using frozen semen, most young fertile mares will conceive over the course of a breeding season. Many factors contribute to the success or failure of the technique, including mare age and reproductive status (maiden, barren, etc.); stallion fertility and semen quality; and appropriate handling and use of the semen. Owners should be aware that pregnancy rates with frozen semen are significantly lower in mares older than 16. Pregnancy rates also depend on the stallion; some stallions’ semen freezes better than others’. For the best chance of success, owners should breed to stallions that are known to have good-quality frozen semen and have produced live foals.
Breeders can purchase frozen semen by the straw, by the dose or by seasonal contract (with pregnancy or live foal guarantee). One semen dose typically provides an industry standard of at least 500 million progressively motile sperm for insemination. Because of the post-thaw motility of frozen semen varies among stallions and semen batches, breeders generally receive four to 12 straws per dose.
Frozen semen is shipped in a special vapor shipper from a distribution facility, then stored in liquid nitrogen at the attending veterinarian’s clinic until the mare is in heat and ready for insemination. Frozen semen can be stored indefinitely in properly maintained liquid nitrogen tanks for a nominal monthly fee. But be sure the semen is covered by the storage facility’s insurance policy.
The cost of a dose or straw of frozen semen varies but is comparable to an average live cover stud fee. Shipment costs will be incurred with both fresh shipped or frozen semen. You might be required to pay an additional rental fee for the vapor shipper container for frozen semen, whereas you’ll pay a stallion collection fee for fresh semen batches.
It’s slightly more expensive to breed with frozen vs. fresh because of the increased cost of managing the mare. Because frozen semen must be inseminated very close to the time of ovulation (usually within six to 12 hours), the mare requires more frequent ultrasound examinations and palpation. The cost of insemination might also be slightly higher due to the specialized equipment and expertise necessary when using frozen semen.
However, you do not need to have your mare at a clinic for breeding with frozen semen. Your ambulatory veterinarian can perform the insemination on your farm. Work with a practitioner who is experienced with this method, as timing and handling of the semen is an important factor in determining success. Also, ensure your facility has ample power and lighting for the veterinarian to work.
Semen can be collected and frozen from any stallion, provided he is sexually mature, is trained to be collected and has adequate fertility and semen quality. Semen cryopreservation can be performed on the farm, but only if the veterinarian is experienced with handling and other techniques. Remember that some breed organizations (e.g., The Jockey Club), do not allow owners to register foals produced via this method.
About the Author: Lauren M. Gallaspy, DVM, practices with Old Dominion Equine Associates in Keswick, Virginia This article is provided courtesy of AAEP Media Partner, The Horse.