Equis ISSN 2398-2977

Semen: liquid preservation

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

Introduction

  • Preservation of semen in liquid form is carried out for inseminating fresh or chilled semen into mares that belong to breed societies allowing the use of AI.

Wetherbys Thoroughbred Register still does not allow breeding by any method other than natural cover.

  • Semen preserved in an extender can be inseminated hours or days following collection. Good pregnancy rates have been reported with semen stored for 4-5 days after collection with some stallions.
  • Longevity is related to fertility of the stallion, the intrinsic ability of his semen to withstand the cooling process, and good preserving technique.
  • Spermatozoa are at risk from a variety of environmental factors including temperature, light, chemicals and surfaces into which it comes into contact, and physical trauma.

Uses

  • Preserving semen in liquid form is used for the artificial insemination of mares within hours or days (typically 1-2 days but very rarely as long as 4 or 5 days) after collection thereby increasing the longevity of the sperm outside the mare's reproductive tract.
  • To assist stallions with low fertility by increasing longevity of the sperm.
  • Semen with potentially pathogenic bacteria within it can be treated with extender containing antibiotics to which the bacteria are sensitive.

Advantages

  • Mares and their foals do not have to travel to a stud thereby saving on transport stress, boarding fees and the risk of disease spread amongst groups of visiting animals.
  • Stallions can have a larger book with fewer coverings if sperm count and quality are adequate to provide a number of doses containing the minimum insemination dose of 4-500 million progressively motile sperm per ejaculate.
  • Sperm can be kept for insemination at the optimal time for fertilization of ovum.
  • Pregnancy rates can be higher than for natural covering due to minimal contamination techniques at insemination.
  • Risk of trauma to valuable horses eliminated from natural covering.
  • Chilled semen can be transported within countries and between countries, eg across Europe.
  • Venereal disease control can be enhanced by the fact that stallions do not come into physical contact with mares.

Disadvantages

  • Individual variation amongst stallions means not all will have semen that preserves well in various types of semen extender. Trial and error is involved at the testing stage.
  • Increased degree of veterinary involvement means that AI is not a cheaper alternative to natural cover.
  • If correct biosecurity measures are not followed for stallions being used in an AI program, liquid preservation of semen acts as an efficient and rapid means of transmitting venereal disease.

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

  • Good fertility can be expected.
  • The use of minimal contamination breeding technique for mare also reduces early embryo mortality.

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • 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.

Other sources of information

  • Horserace Betting Levy Board (2016)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:http://codes.hblb.org.uk.
  • Campbell M L H (2009)How to Collect, Process and Certify Equine Semen.In:Proc 48th BEVA Congress. Birmingham. pp 42-43.
  • Timoney P J (1998)Aspects of the Occurrence, Diagnosis and Control of Selected Veneral diseases of the Stallion.In:Proc Stallion Reprod Symp.pp 76-83 (Am Coll Therio).
  • Darenius A (1998)Experiences with Chilled, Transported Equine Semen.In:Proc Stallion Reprod Symp.pp 60-70 (Am Coll Therio).
  • Watson E (1995)Artificial Insemination in Horses. In PractFebruary. pp 54-58.
  • Barrelet F (1992)Handling Stallion Semen for AI.In:Equine Stud Medicine & Artificial Insemination Course - 3-7th February 1992.British Equine Veterinary Association and R&W Publishing. pp 105-108.
  • Colahan P Tet al(1991)Equine Medicine and Surgery.4th edn. Vol 2. American Veterinary Publications, Inc. ISBN: 0 939674 27 0. pp 8570 (Concise summary of main points).


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