Equis ISSN 2398-2977

Semen: cryopreservation

Contributor(s): John Dascanio, Graham Munroe, Vetstream Ltd, Elaine Watson, Madeleine L H Campbell

Introduction

  • 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, allows for international utilization of genetic material without transporting the stallion, and provides the opportunity to preserve semen from a stallion before gelding.
  • Preservation at temperatures (-196°C/-320.8°F) where spermatozoa can be stored indefinitely.

Uses

  • Efficient use of stallion when he is free from competition commitments.
  • Storage of collected semen for an indefinite period to be used nationally, internationally or after the stallion's death (depending on stud book regulations).

Advantages

  • Reduce the risk of injury associated with live cover (as do all forms of semen collection and insemination).
  • Reduce transportation of breeding horses and associated costs.
  • Increase distribution of semen from the better stallions.
  • Remove constraints of location to choice of stallion.

Disadvantages

  • 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/service (pregnancy/insemination in c3-40% nationwide in the UK compared to about 70-80% for freshly collected semen, assuming a normal mare and normal stallion).
  • Cryopreserving semen is expensive.
  • 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.
  • As with all forms of artificial insemination, all of the venereal diseases that can be spread by live cover can be spread using collected and preserved semen, and there is an increased potential to spread them far and wide by shipping frozen semen.

Requirements

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Preparation

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Procedure

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Aftercare

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Outcomes

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Prognosis

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

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Ferreira-Silva J, Lima Basto S et al (2018) Freezing of stallion semen: in vitro evaluation of motility and acrosin activity in sperm cells cryopreserved using different semen extenders. Biopreservation and Biobanking 16 (6), 439-443.
  • Ramires Neto C, Monteiro G A et al (2013) New seminal plasma removal method for freezing stallion semen. Theriogenology 79 (7), 1120-1123.
  • Squires E, Barbacini S et al (2006) Retrospective study of factors affecting fertility of fresh, cooled and frozen semen. Equine Vet Educ 18 (2), 96-99 VetMedResource.
  • Feary D J et al (2005) Chemical ejaculation and cryopreservation of semen from a breeding stallion with paraphimosis secondary to priapism and haemorrhagic colitis. Equine Vet Educ 17 (6), 299-304 VetMedResource.
  • Samper J C & Morris C A (1998) Current methods for stallion semen cryopreservation - a survey. Theriogenology 49 (5), 895-903 PubMed.
  • Dobrinski I, Thomas P G and Ball B A (1995) Cryopreservation reduces the ability of equine spermatozoa to attach to oviductal epithelial cells and zone pellucide in vitro. J Androl 16 (6), 536-542 PubMed.

Other sources of information

  • Horserace Betting Levy Board (2019) Codes of Practice. 5th Floor, 21 Bloomsbury Street, London WC1B 3HF, UK. Tel: +44 (0)207 333 0043; Fax: +44 (0)207 333 0041; Email: enquiries@hblb.org.uk; Website: codes.hblb.org.uk.
  • McCue P M (2014) Semen Freezing. In: Equine Reproductive Procedures. Eds: Dascanio J J & McCue P M. John Wiley & Sons Inc, USA. ISBN: 9780470960394.
  • Briggs K (1997) Freezing Semen. In: The Horse: Your Guide to Equine Health Care. 14 (12), 56-60. ISSN: 1081-9711. 
  • Barrelet F (1992) Handling Stallion Semen for AI. In: Equine Stud Medicine & Artificial Insemination Course. British Equine Veterinary Association and R&W Publishing, UK. pp 107.
  • Colahan P T et al (1991) Equine Medicine and Surgery. 4th edn. American Veterinary Publications Inc, USA. ISBN: 0939674270. pp 876 (Concise summary of main points).
  • Pickett B W, Amann R P & Squires E L (1987) Semen Preservation. In: The Stallion, Artificial Breeding & Embryo Transfer. In: Proc The University of Sydney Post-graduate Committee in Veterinary Science. 94, pp 203-213.


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