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Assisted Reproduction

The various techniques of assisted reproduction are widely used in the breeding of Pleasure and Performance horses. AEH has a number of veterinarians experienced in all aspects of equine reproduction and we regularly collect stallions and inseminate mares for our clients.

Artificial Insemination

Artificial insemination (A.I.) is the placement of semen into the uterus of a mare at the time of ovulation. It is performed by means of a catheter inserted through the mare's cervix by a veterinarian.

A.I. is used in horses for a number of reasons including the availability of the stallion, as an aid in managing mares with reproductive difficulties, to decrease the workload and increase the efficiency of the stallion, in the event of injury to the mare or stallion which may prevent normal service and in controlling venereal disease.

Successful A.I. involves regular ultrasound examination and monitoring of the mare's cycle and necessitates close communication between the mare owner, the veterinarian and the semen provider.

Three methods of A.I. are used in horses:

  • Fresh semen is collected and used almost immediately on the farm at which it is collected, this method enables more efficient use of the stallion and may help pregnancy rates for stallions of marginal fertility.
  • Chilled semen involves collection, dilution with extender, cooling and transport of semen to the mare for use within 36 hours. This method can be used from any fertile stallion from any location that can ensure reliable transportation of the semen to the mare.
  • Frozen semen is collected and extended then frozen and stored in straws in liquid nitrogen. This technique allows access to semen from horses which are located overseas, currently competing, injured or even dead. Using frozen semen is convenient because the semen is available to be used when needed, but requires more intensive management of the mare as the technique demands timing of insemination close to ovulation of the mare's follicle.

AEH has several experienced equine reproduction veterinarians able to advise and assist in managing mares for artificial insemination whether it is with fresh, chilled, or frozen semen.

Call us to discuss how these techniques can be used to assist you in breeding your mare.

Frozen Semen

Frozen semen has several distinct advantages over fresh and cooled semen.

  • The genetics of a valuable stallion can be preserved indefinitely by collecting and storing doses of frozen semen during the non-breeding season.
  • Frozen semen can be sent to the mare farm as soon as the contract or breeding agreement is signed, eliminating the need for same-day or overnight courier service, as is required with cooled semen
  • Frozen semen can be exported overseas

The primary disadvantages of frozen semen in an equine breeding program are stallion variability in response to freezing, cost to collect, freeze and store semen, intensified mare management, and slightly lower pregnancy rates per cycle.

Sperm from some stallions do not tolerate freezing and thawing. Consequently, post – thaw motility and pregnancy rates can vary greatly between stallions. Performing a 'test freeze' is very valuable in determining if semen from a stallion can be frozen successfully and which freezing extender is most suitable for each stallion. A minimum of 30% progressive motility should be present post-thaw for a stallion to be considered a 'good freezer'. Proper storage and handling of frozen semen is critical for future success.

The number of straws required for a breeding dose is dependent on the total number of sperm in the straw and the insemination technique. The mare is examined 3 to 4 times per day as ovulation approaches and the mare is inseminated immediately after ovulation is detected.

Prediction of ovulation and timing of insemination with frozen semen is facilitated by administration of ovulation-inducing agents, such as hCG or deslorelin. Typically, a mare in oestrus would be given one of these agents once a follicle larger than 35mm in diameter is detected. In most instances, ovulation will occur in 36 to 40 hours after hCG or deslorelin administration.

Average pregnancy rates per cycle for mares bred with frozen semen are 30 to 40%. Some stallions may have per cycle pregnancy rates of 50 to 70% using frozen semen, while frozen semen from other stallions will be unsuccessful in getting mares in foal. In general, pregnancy rates per cycle using frozen semen are 5 to 10% lower than with cooled-transported semen.

Management of mares for breeding with frozen semen may seem intimidating. However, by following a few simple guidelines, frozen semen can be used very successfully in a breeding program.