The mare is seasonally polyoestrus meaning that she responds to increasing daylength and is fertile during the spring and summer months. 

Although under New Zealand conditions this means that mares can breed as early as August/ September often it is easier to breed mares in the months of October – December.

During these warmer months the mares season or ‘heat’ is about five days long with the mare ovulating at the end of this period.  The mare comes into season every three weeks during the breeding season.

With the assistance of your veterinarian it is possible to breed your mare using AI to stallions from anywhere using either chilled or frozen semen. Chilled semen is available from stallions resident in NZ or sometimes Australia.  Frozen semen can keep indefinitely and therefore can be from international stallions. 

Fertility is generally better with chilled semen compared to frozen semen. Factors affecting the fertility of the mare and her ability to conceive and deliver a foal include her age, how many foals if any she has had and the health and conformation of her reproductive tract.  An assesment of the mare can help you make a decision on how to breed your mare.

Typically a mare requires several ultrasound examinations by your vet to prepare her for breeding. 

Alongside these examinations drugs are sometimes used to regulate the ovulation of the mare so that it can be closely aligned with the insemination of the mare.  Other drugs are also used to bring the mare in to season.

Once served the mare can be scanned for pregnancy 15 days after ovulation.  The mare gestation is approximately 340 days, or 11 months and 11 days.

Breeding a horse is not for the faint hearted, there can be problems and disappointments along the way.  But ultimately it can be rewarding to see progeny that you were responsible for breeding performing well.