• Artificial Insemination

  • Why Choose AI for Your Mare?

    For the mare owner considering breeding from a mare, the decision of whether to proceed with natural cover vs. A.I. will depend on several factors. These may include:

    •  The availability of the stallion : Many sports horse stallions will only be available by A.I. due to competition commitments or concerns about the stallion suffering injury during covering.


    •  The age and breeding history of the mare: A.I. is particularly suitable for mares with lower fertility that are difficult to get in foal. These may include older mares or mares with poor vulval conformation which are prone to uterine infection (endometritis).
    • The location of the stallion: A mare may go to a stud close to home and the semen can be brought in from elsewhere in the UK or abroad. This removes the need to subject the mare to long-distance travel and allows her to return home between ultrasound scans, insemination and pregnancy diagnosis, if desired.
  • Advantages of A.I.

    Artificial insemination has several advantages over natural cover. These include:

    • Mares may be bred to a stallion many miles away or abroad, without the need to transport them vast distances.
    • There is a lower risk of uterine infection (post-breeding endometritis), 
      which is the most common cause of low fertility.
    • Mares may be bred with frozen semen from a stallion which has 
      since died.
    • It is considerably safer for the mare, stallion and the handlers.
  • Choice of Semen: Fresh, Chilled or Frozen? A.I. may be performed with fresh, chilled or frozen semen. The choice is often governed by the availability of the desired stallion. Historically, conception rates have been highest with fresh semen, followed by chilled then frozen semen. As insemination techniques have developed, however, the use of good quality frozen semen in fertile mares frequently produces conception rates to equal fresh/chilled A.I.

  • Fresh Semen A.I

    Suitable when the stallion undergoes semen collection at Ashbrook, or is located no more than two hours away from the mare.

    Particularly recommended for sub-fertile mares

    Chilled Semen A.I

    Often available from stallions in other parts of the UK or Continental Europe

    The semen is usually couriered to Ashbrook overnight

    Frozen Semen A.I

    The semen is collected at stud and frozen in liquid nitrogen where it lasts indefinitely

    Suitable for stallions located worldwide

    Suitable for competition stallions which may only be available for breeding/semen collection for a limited period.

    We routinely use a 'deep intra-uterine' insemination technique to deposit the semen at the very tip of the uterine horn.

  • Procedure for A.I

    Before joining the A.I programme at Ashbrook, mares must have a clitoral swab taken for Contagious Equine Metritis (CEM) and blood samples taken for Equine Viral Arteritis (EVA) in accordance with HBLB and BEVA Codes of Practice.

    Mares initially undergo an examination to assess their suitability for breeding and identify any conditions that may impair fertility e.g uterine infection

    When the mare is in season she is admitted to Ashbrook for daily or every other day scanning to detect the optimum time for insemination. Depending on whether the

    Semen is fresh, chilled or frozen, insemination is performed shortly before or after ovulation

    Mares are routinely scanned 4-12 hours post-insemination to check for evidence of excessive inflammation (post breeding endometritis). Uterine lavage with sterile saline is usually performed to remove any dead sperm and inflammatory cells from the uterus. The live sperm are in the fallopian tubes (oviducts) at this stage and are not washed out or damaged by this procedure.

    Antibiotics may be infused into the uterus and oxytocin injections administered to encourage the uterus to contract and expel residual fluid.

    Most mares are discharged 24-36 hours after insemination

    Pregnancy Diagnosis

    An ultrasound scan is performed 14 days after ovulation. If in foal, follow-up scans at 24 and 44 days are recommended to check the pregnancy is progressing normally.


    In addition to routine vaccinations against Equine Influenza and Tetanus, we recommend that pregnant mares are vaccinated against Equine Herpes Virus (Types I and IV), which is known to cause abortion. Vaccination is performed at 5, 7 and 9 months of gestation.