Artificial Insemination (AI)

Artificial insemination (AI) is a popular procedure for breeding sports horses, with semen now readily available from stallions worldwide. Rossdales is approved by BEVA to provide AI services with fresh, chilled or frozen semen. Rossdales’ vets have performed many successful inseminations, ranging from straightforward mares to more complex cases.

Health and safety benefits of AI are well recognised and conception rates with fresh, chilled or even frozen semen often equal or exceed expectations from natural service. Successful AI depends on a detailed understanding of the mare's oestrus cycle, a comprehensive understanding of the mare’s breeding history and in some cases the use of advanced reproductive techniques.

Pre-Breeding Examination

A full reproductive examination should be performed to assess your mare’s suitability for breeding and highlight any potential reproductive problems. This will also allow assessment of the stage of you mare's oestrus cycle and will determine timing of further examinations prior to insemination.

Clitoral swabs for contagious venereal disease (CEM) will be required, together with blood samples to be tested for infectious disease such as EVA. It may also be useful to take an endometrial swab to help assess the mare's uterine environment. Follicular activity is followed closely along with other parameters and when the follicle has reached a suitable size for breeding, hormones will be given to induce ovulation. Timing of induction will be largely determined by which type of semen is chosen  and which induction agent is used.

Fresh, chilled or frozen semen?

Management of the mare and timing of insemination will be determined by which semen is chosen: fresh, chilled or frozen. For fresh or chilled semen, conception rates are highest when insemination is performed within 24 hours preceding ovulation.

Chilled semen

Insemination with chilled semen requires good communication with the stallion stud so that semen is delivered on time.

Considerations with chilled semen:

  • Check that the stallion's semen chills and travels well 
  • Find out which days of the week they collect from the stallion and how much notice you will have to give for them to collect and send the semen.
  • How many doses of semen are you buying and are transport costs included? 
  • Semen coming from abroad MUST be accompanied by the relevant health certification.

Frozen semen

Frozen-thawed semen has a relatively short life span and therefore requires that mares be inseminated immediately before or after ovulation. Subsequent management of mares for insemination with frozen-thawed semen is more intensive and mares require multiple ultrasound examinations to assess the correct time for insemination. 

Advantages, however, are that breeders can use of stallions which are still competing or which are based abroad.  Also, the semen can be sent well in advance of the mare being in oestrus, avoiding the last minute delivery of chilled semen, which may not arrive on time.

  • When purchasing frozen semen, buy from a reputable stud and ask for details on semen quality and post thaw motility. 
  • How many doses of semen are included in the price? Will there be extra transport costs?
  • Semen must be correctly transported to be viable.
  • Frozen semen should be shipped to us to store in our liquid nitrogen container prior to preparing the mare for insemination.
  • Semen coming from abroad MUST be accompanied by the appropriate health certification.

Following insemination

Following insemination, your mare will be checked for ovulation and for post-breeding inflammation. Treatment may be required following insemination, especially in older or problematic horses. Provided all is well, your mare will be scanned at 16 days following ovulation and if pregnant, it is advised that scans are performed at 28 and 45 days to make sure the pregnancy is developing normally. Older or problematic mares may require supplementary progesterone in this early period.


If you would like to discuss options for AI for your mare, please contact Andrew McGladdery or Fred Barrelet on 01638 663150.