Covering the Mare

Covering the mare

When you want to breed your mare there are 2 options to cover her: natural cover and artificial insemination (AI).

Natural cover

  • the mare is bred naturally to a stallion

  • may be paddock served, where the mare runs with a stallion for several days/weeks

  • may be handheld and covered when she is "teasing" and/or when a scan suggests that she is close to ovulation

  • some studs require a clean clitoral and/or uterine swab prior to being covered

  • to protect the stallion from being kicked the mare might need to wear serving hobbles and boots and she may need to be twitched and/or sedated

  • we prefer covering the mare every second day until she is no longer teasing as every day covering increases the risk of fluid development and may reduce fertility

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Artificial insemination:

  • the mares are inseminated with semen collected from the stallion

  • AI is not allowed for foals that are to be registered in the Australian Thoroughbred Stud book

  • semen collection reduces the risks to the stallion

  • the semen can be assessed for morphology, motility and sperm concentration

  • the semen may be split into multiple doses depending on the concentration

  • Mare (and foal) don't have to travel to the stallion

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Chilled semen: the semen gets mixed with an extender post collection and chilled for immediate transport and insemination. The semen is ordered when the mare has a follicle >35mm, endometrial folds >2 and a softening cervix. The vet can give chorulon or ovuplant at this time in an effort to synchronise ovulation as close as possible to semen arrival.

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Frozen semen: the semen gets separated from the seminal plasma, mixed with a freezing extender and frozen and stored/transported in liquid nitrogen tanks. Frozen semen can be transported all over the world and stays viable after many years of storage. This allows diversity of genetics and allows to choose a stallion with characteristics that complement the mare.  Semen must be purchased and stored prior to the mare's cycle commencing. The mare is given chorulon or ovuplant when she has a follicle >35mm and endometrial folds of 3 to schedule her ovulation so it occurs within 32-44 hours. Once scheduled the mare needs to be at the clinic so she can be scanned every 6 h until ovulation when she will be AI'd.

  • The day after AI the mare should be scanned to assess if the semen has caused any reaction such as fluid. She may need antibiotic uterine infusion/flush, anti-inflammatories, oxytocin and /or systemic antibiotics.

  • If an embryo is being collected the uterus undergoes an ‘embryonic flushing’ procedure around 7 days post-ovulation and any resulting embryo is transplanted into a specially synchronised surrogate mare.

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Zoe Meyer