In Thoroughbreds, 50 - 60% of mares conceive in each oestrous cycle after natural mating and by the end of the breeding season 89% of mares are pregnant. However only 79% of mares go on to produce a live foal.

When fresh or good quality chilled semen is used for artificial insemination (AI) we expect slightly higher per cycle pregnancy rates compared with natural mating. It normally takes 1 – 2 cycles for a fertile mare to conceive.

The fertility of frozen semen ranges from 0 – 70% per cycle due to the variability of the “freezability” of different stallions. The international pregnancy rate is around 40% per cycle. It normally takes 2 – 3 cycles for a fertile mare to conceive.


Breed from young mares!  Older mares, greater than 14yo have reduced fertility. These mares are more prone to uterine infections and cysts. Generally, either fresh or chilled semen works better than frozen semen in these mares.

A pregnant uterus is a healthy uterus! Mares with a foal at foot and young maidens (3 – 10yo) are usually the most fertile group of mares. Barren mares usually benefit from insemination with fresh or chilled semen and save your frozen semen for when she has a foal at foot.

Use good quality semen: Do your homework! We can obtain semen from almost anywhere in the world if you can provide us with contact details for the stud. Make sure you buy a dose of more than 300million motile sperm and that the semen is handled by professionals.


Non pregnant mares: Ask your regular vet to treat your mare with an injection of prostaglandin (PG) and then organise to deliver your mare to EquiBreed 3 days later. Or we can do it for you as part of your programme.

Foaling mares: Once your mare has foaled then she should be checked 9 days later by your regular vet to make sure her uterus is healthy. Normally we do not recommend using artificial insemination in mares during foal heat. An easy protocol is to organise to treat the mare with a PG injection on day 21 after foaling. Three days after her injection she can be brought to EquiBreed for breeding management.


Natural mating: We can manage your mare’s breeding programme and “walk her in” to the stallion for natural mating. We also manage her after breeding to confirm ovulation and minimise the risk of infection.

Fresh / chilled semen AI: The management of the mare for AI is similar to that for natural mating. We examine your mare multiple times to get the timing right for ordering the semen, AI and to treat post breeding infections.

Frozen semen: Frozen semen only survives for about 6h after thawing. We aim to inseminate your mare with frozen semen within 2-4h of ovulation. So we are scanning mares all day and night for you!

Epididymal sperm: If you have produced an amazing colt and would like to breed from him and geld him….we can freeze his epididymal sperm at the time of gelding and then inseminate your mares with frozen epididymal sperm.

Sex sorted semen: This is now available in New Zealand as a result of a collaboration between Sexing Technologies and EquiBreed NZ. If you would like to choose the sex of your foal at the time of insemination then please contact us.

Semen evaluation: All semen used at EquiBreed NZ is evaluated and recorded by our computerised semen analysis system.

Pregnancy diagnosis: At EquiBreed NZ, mares are scanned for pregnancy several times between 2 and 6 weeks after breeding. Twin treatment is successful in 90% of cases if treated between 14 – 16 days after ovulation. Most pregnancy loss occurs between 20 and 30 days so we also recommend that a pregnancy scan be performed every 14 days until she is 45 days pregnant.




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HISTORY MADE BY WAIKATO’S EQUIBREED Waikato company EquiBreed NZ have made history with the birth of New Zealand’s first foal produced by an in vitro fertility treatment using intracytoplasmic sperm injection (ICSI). Company principal Dr Lee Morris says it is a watershed moment for both EquiBreed and New Zealand. “The ability to produce foals using this fertility...
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