Semen: cryopreservation

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  • Cryopreservation of semen is a growing facility in equine stud medicine.
  • It increases the flexibility of a stallion that may be competing during a stud season and allows for international utilization of genetic material without transporting the stallion.
  • Preservation at temperatures (-196°C) where spermatozoa can be stored indefinitely.


  • Efficient use of stallion, collecting semen when 'jump' mare is ready and stallion is free from competition commitments.
  • Storage of collected semen for an indefinite period to be used internationally.


  • Reduce the spread of venereal and other infectious diseases.
  • Reduce transportation of breeding horses and associated costs.
  • Increase distribution of semen from the better stallions.
  • Remove constraints of location to choice of stallion.
  • Can improve upon marginal fertility in some mares and stallions.


  • Individual variation in spermatozoa survivability. Some stallions have sperm that do not freeze well and result in very poor pregnancy rates.
  • Decrease in live foal rates.
  • High costs of veterinary input to prepare mare.
  • Stringent import requirements for different countries require the stallion to be kept at varying levels of quarantine before and during collection of semen for export. This may preclude him from covering outside mares during this time.


Materials required

Ideal equipment

  • Centrifuge for concentrating the spermatozoa.
  • Cryopreservation extenders.
  • Straws, 0.5-5 ml, or tubing, aluminum or plastic, 5-25 ml.
  • Liquid nitrogen in storage tanks.




  • Loss of fertility. Currently the technique cannot emulate natural covering or chilled semen covering rates.


  • Completely dependent on individual semen properties after freezing.
  • Expect 20-40% fertility but with a wide variation.

Reasons for treatment failure

  • Stallion's semen not a good candidate.
  • Temperature shock.
  • Abnormalities within the sperm eg vacuoles within the heads.
  • Some cryoprotectants can decrease fertility.
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