Thinking about breeding your mare this season? What you need to know

Mare and foal - foal nursing on mare

A foal that you have bred of your own is a wonderful experience. Before your start the process you need to consider a few things. One of the first thing to consider is what you are breeding for? And when do you need to start? This may be a racehorse, yearling sales prospect, sport horse, or a kids pony. A yearling sales prospect breeder may want an earlier foal, but it might not be as important for a sport horse or general riding horse as they take longer to mature and perform at an older age.

Choosing the right mare is next. Things to consider:

  • The age of the mare
  • Her breeding history
  • General good health
  • Overall conformation
  • Previous offspring
It is important to take these factors into consideration and make sure they align with the purpose you intend on breeding for.

Younger mares tend to be more fertile and have more success at carrying foals to term. Fertility decreases from 13 years of age and uterine pathology starts to become a factor of whether they will carry a foal to term or not, regardless of how many foals they have had or even if they are a maiden mare. For example a 19 year old maiden mare is not a good candidate to breed from. She will have an aged uterus, lower fertility and is more likely to have foaling difficulties if she carries to term. There are tests we can do to determine the likelihood of a mare getting in foal and carrying to term.

Mares with poor vulval conformation will also have a more difficult time getting in foal due to the risk of uterine contamination being higher. The best candidates for breeding are younger mares or mares that have a foal at foot. A pregnant uterus is a healthy uterus.

The next consideration is choosing the breeding method, as there are a few to choose from.Natural breeding has a high in foal rate and is less intensive to manage due to natural semen lasting up to potentially 48 hours inside the mare therefore timing of serving the mare is not as crucial as with other methods. This however limits your stallion choice as you may need to take the mare to the stallion if not in the area.

Chilled semen can last for up to 24 hours in the mare, hence, management needs to be slightly more intensive than natural. It is also important to research where the stallion is based, what days he gets collected and how soon it can get to you, usually either by plane or courier. This helps with planning when the vet should be scanning the mare and when vets can give drugs to help her ovulate at the correct time.

Frozen semen is convenient if wanting to breed from stallions overseas or if the stallion has died. Frozen semen lasts for roughly 6 hours once thawed, this is why it is important the mare is scanned every 6 hours once close to ovulation as the egg, once released, also only lasts for approximately 6 hours.

The more a mare needs scanned and close monitoring the more the costs increase. Cost is also a factor when choosing which stallion to serve your mare with.

Once you have chosen your mare and stallion, the next step is to ensure your mare is in optimal health and fertility. Parasite management and regular dental examination as well as keeping their feet well trimmed all help to keep your mare in optimal condition ready for breeding. Tetanus vaccination is also recommended to be up to date before starting the breeding process.

Depending on whether your mare is in foal or not at the time depends on when vets start scanning. Dry mares are usually scanned towards the end of October in Southland. Due to day length mares start to cycle slightly later then Canterbury and the North Island.

Mares that have a foal at foot can be first scanned 8 or 9 days after the foal was born to catch their foal heat otherwise, particularly for frozen semen, we wait for the next cycle.

The first scan will determine what stage in the cycle the mare is at and how healthy the uterus is. A plan for getting your mare in foal can be made from that first scan.

- Megan Reidie


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