Breeding Your Mare at Twemlows
- November 26, 2025
If you’re thinking about breeding from your mare, whether she’s a first-time broodmare, an older companion, or still actively competing, Twemlows Stud Farm offers world-class care and advanced reproductive services to give her the best chance of success. As one of the UK’s leading equine reproduction centres, here at Twemlows we provide a full suite of breeding services supported by our on-site team of specialist reproductive vets who are available 24/7. Your mare will receive expert monitoring and care throughout the entire breeding process, from initial scans to foaling and everything in between.
Where to Begin?
It’s good to begin your breeding journey in late March or April. Most mares start to cycle in the spring, but starting early allows you more time should any problems arise, before mares stop cycling in late summer/autumn. Mares will typically come into season once every 21 days through spring and summer, and it is advisable to start tracking as early as you can.
Once you know she is cycling, breeding your mare begins with a fertility health check where we use ultrasound to examine her ovaries and uterus. We may also do a speculum exam and take a few samples and swabs to check for any abnormalities and to be sure she is free from infection.
In order to provide the best service possible, it is very import that we have a detailed discussion with you about her history, health, current activity levels, any previous reproductive history and your breeding wishes, so we can offer the best advice on how to proceed. Each mare is different and every mare we see gets their own tailored plan.
Artificial Insemination
Artificial Insemination (AI) is a proven and popular choice for breeding, and with good reason. AI offers an effective, safe, and flexible way to breed your mare without the risks and logistics involved with natural cover. We specialise in AI at Twemlows and use raw, fresh, chilled, or frozen semen depending on your mare’s individual needs. Fresh and chilled semen typically give the highest conception rates and lends itself to stallions who are nearby. We are fortunate to be located next door to Stallion AI Services who are the home to several world class stallions.
Whichever stallion or semen type you choose for your mare AI allows us to breed your dream foal. Chilled semen is commonly used across the UK and Europe (requires a health certificate) and arrives ready for use the following day. When using fresh and chilled semen we scan the mare regularly, to identify the best time to inseminate her, which is within the 12-24 hours before she ovulates. We perform a repeat scan after 24 hours of insemination to check that she has ovulated.
Frozen semen, while slightly less fertile, allows access to stallions worldwide and can be stored for future use making it a fantastic option for rare or in-demand stallions. For frozen semen your mare is scanned regularly until ovulation occurs to accurately time the ovulation and insemination.
If semen is to be imported it will need an import health certificate, which the stallion stud or agent will be able to arrange for you. We can guide you or act on your behalf, when communicating with the stallion owner to gather key information such as his semen availability and his first cycle conception rates.
As well as opening the gene pool to stallions globally, AI also has significant welfare and logistical advantages. It removes the physical risk to both stallion and mare associated with natural cover; it reduces the risk of disease transmission and removes the need to travel mares to the stallion.
Embryo Transfer
Embryo Transfer (ET) has transformed modern breeding, especially for performance mares who are still competing, mares with health conditions that make pregnancy risky, or mares you would like to breed from more than once in a season.
ET works by artificially inseminating your mare (the donor mare) and then flushing the embryo 7 to 8 days later. The embryo is then transferred into another mare, the recipient mare, who will carry the pregnancy to term, foal down, and nurse the foal until weaning. It’s an established, non-surgical procedure, performed routinely at Twemlows with outstanding success rates.
The key to successful ET lies in careful synchronisation. Our vets work to ensure that both donor and recipient mares ovulate within a narrow window, allowing for the embryo to be transferred at exactly the right time. Seven days after transfer, the recipient mare is scanned to confirm pregnancy, with further scans over the next four weeks to monitor the embryo development.
Consideration does need to be given to the stallion, donor mare and recipient mare. Fresh and chilled semen tends to give higher embryo retrieval rates. We use frozen semen on a regular basis and have good success although it is important to use a stallion with good semen quality. The donor mare, while not carrying the pregnancy to term, does need to ovulate and carry the embryo for its first seven-eight days until it is flushed out. A healthy uterus is important as any infection or fluid retention can have a negative effect on embryo survival. The recipient mare obviously needs to be reproductively sound and in good general health. We usually aim to use a recipient similar in size to the donor mare.
ET is an attractive option for competition mares as it allows her to continue competing uninterrupted. What’s more, because embryos can be flushed multiple times in a season and transferred to different recipients, your mare can produce multiple foals in a single year which is an invaluable option for owners of elite or older mares.
Do I Need to Provide a Recipient Mare?
No. As well as our skill at performing successful ET, a standout feature of Twemlows is our large recipient mare herd. We are home to over 280 recipient mares, meaning you can carry out ET on your own mare, even if you don’t have a recipient mare lined up. Our well-loved herd of recipient mares are diverse in size and breed allowing us to select the ideal mare to match yours.
OPU & ICSI
For mares with subfertility issues or those unable to produce embryos via traditional methods, Ovum Pick-Up (OPU) and Intracytoplasmic Sperm Injection (ICSI) is an advanced breeding technology that offers a solution.
OPU involves the collection of eggs directly from the follicles in the mare’s ovaries using ultrasound-guided aspiration. These oocytes are then shipped to specialist laboratories in Europe, where the ICSI procedure is performed. During ICSI, a single sperm cell is injected directly into each mature oocyte, bypassing many of the natural barriers to fertilisation.
Embryos are then cultured for 7–9 days before being frozen and transferred back to Twemlows for implantation or stored for future use. This method is ideal for mares who are not cycling, have limited fertility, or for using rare or limited availability semen. Some high-performance stallions are only available via ICSI. A single straw of semen can often be used for multiple ICSI attempts, making this an efficient option for breeding from valuable or ageing stallions.
Foaling Services
Once you have your mare in foal, Twemlows offers a full foaling service. Our experienced foaling team is on site 24/7 to care for and monitor your mare and they are supported by our team of 4 resident vets, should the need arise. We use foaling alarms and have cameras in all our foaling boxes. Post foaling, both your mare and newborn foal will have a full examination by our vets. This includes ensuring the mare’s placenta has fully passed and that the foal has received enough essential colostrum from the mare and checking the foal’s limbs and umbilicus.
We can care for your mare and foal all the way through to weaning and beyond, up to 3 years old for the youngsters.
Twemlows is recognised across the UK as a centre of excellence in equine reproduction. From initial consultations to pregnancy scanning, foaling, and advanced techniques like Embryo Transfer, OPU and ICSI, every aspect of our service is carried out by a highly experienced and dedicated team. Our resident reproductive vets are on site 24/7, meaning your mare receives continuous care at every stage and we are fully confident in our ability to put your mare in foal, no matter your previous experiences of breeding. Our extensive recipient mare herd provides unmatched reliability for embryo transfer, and our laboratory team is skilled in managing semen from around the world, ensuring that no detail is missed. Twemlows offers everything you need to turn your mare’s breeding potential into success.
