ISSN 2398-2977      

Embryo Transfer

pequis

Introduction

  • Collection of an embryo from a donor mare and transferring it to the reproductive tract of a synchronized recipient mare.
  • First recorded in the 1970s for use in the horse.
  • Not all breed authorities will allow embryo transfer, particularly the Thoroughbred Books.
  • Some breed authorities limit the number of embryo transfer foals which may be registered per mare per year.
  • Considerable organization, veterinary attention and expense are involved.
  • The technique has become increasingly popular in recent years, particularly since non-surgical transfer became the norm.

Reasons for embryo transfer

Increased production from valuable mares
  • Increase the number of foals it is possible to breed from a mare per year or lifetime.

May not be possible to register more than one foal per year in some breed associations.

  • Production of a foal from performance mares whilst still performing.
  • Management of mares which are unable to carry a foal safely to full term themselves, eg due to previous colic surgery/a ventral rupture.
  • Some subfertile mares with specific problems, eg cervical injuries, may be good candidates for embryo transfer. However, recent research shows that transferring embryos from old mares with a history of early embryonic death Abortion: early embryonic / fetal death, into young recipients did not increase foaling rates, ie embryo transfer is not a useful technique in old mares with embryonic failure, because the fundamental problem is at the level of the aged oocyte.
  • Generally, subfertile mares have lesser embryo recovery rates than normal mares, and their embryos have a higher failure rate post-transfer than embryos of normal mares.
Assessment of fertility
  • Occasionally used as a means to assess fertility of mares or stallions particularly in the latter case where semen is to be processed Semen: cryopreservation.

Selection of participants

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Synchronization of ovulation

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Insemination of the donor mare

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Embryo recovery

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Embryo transfer

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Success rates

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Campbell M L H (2014) Embryo transfer in competition horses: Managing mares and expectations. Equine Vet Educ 26 (6), 322-327 VetMedResource
  • Scherzer J (2011) Artificial insemination and embryo transfer in mares. Comp Cont Educ Vet 33 (7), E1-5 PDF Download.
  • Campos-Chillon L F et al (2009) Vitrification of early-stage bovine and equine embryos. Theriogenology 71 (2), 349-354 PubMed.
  • McCue P M, Patten M, Denniston D D, Bruemmer J E & Squires E L (2008) Strategies for using eFSH for superovulating mares. J Equine Vet Sci 28, 91-96 VetMedResource.
  • Wisher S & Allen W R (2004) An improved method for nonsurgical embryo transfer in the mare. Equine Vet Educ 16 (1), 30-44 VetMedResource.
  • Squires E L, Carnevale E M, McCue P M & Bruemmer J E (2003) Embryo technologies in the horse. Theriogenology 59 (1), 151-170 PubMed.
  • Squires E L et al (1999) The current status of equine embryo transfer. Theriogenology 51 (1), 91-104 PubMed.
  • Camillo F et al (1997) The use of early pregnant mares as embryo recipients. Equine Vet J Suppl 25, 77-79 PubMed.
  • No Authors Listed (1997) Equine Embryo Transfer IV. Proceedings of the 4th International Symposium on Equine Embryo Transfer. Reims, France, 16-18 January 1997. Equine Vet J Suppl 25, 6-112 PubMed.
  • Seidel G E Jr (1996) Cryopreservation of equine embryos. Vet Clin North Am Equine Pract 12 (1), 85-99 PubMed.
  • Philpott M (1993) The dangers of disease transmission by artificial insemination and embryo transfer. Br Vet J 149 (4), 339-369 PubMed.
  • Katila T et al (1989) Embryo transfer in subfertile mares. Acta Vet Scand 30 (3), 329-333 PubMed.
  • McKinnon A O et al (1988) Equine embryo transfer. Vet Clin North Am Equine Pract 4 (2), 305-333 PubMed.
  • Sirois J et al (1987) PGF-2 alpha release, progesterone secretion and conceptus growth associated with successful and unsuccessful transcervical embryo transfer and reinsertion in the mare. J Reprod Fertil Suppl 35, 419-427 PubMed.
  • Juliano M F et al (1985) Effect of age of equine embryos and method of transfer on pregnancy rate. J Anim Sci 60 (1), 258-263 PubMed.
  • Squires E L et al (1982) Factors affecting reproductive efficiency in an equine embryo transfer program. J Reprod Fertil Suppl 32, 409-414 PubMed.
  • Douglas R H (1982) Some aspects of equine embryo transfer. J Reprod Fertil Suppl 32, 405-408 PubMed.
  • Imel K J et al (1981) Collection and transfer of equine embryos. JAVMA 179 (10), 987-991 PubMed.

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