It's the time of year to begin thinking about breeding your mare. Assuming that you have already chosen a stallion and the time of year that you want your foal to be born, now it is time to set up a 'game plan' to get your mare ready.
First, you need to get the mare into heat. Horses are seasonally polyestrous, which means that they stop cycling, usually in the late autumn, and do not begin again until the early spring. However, you can alter this process by putting them under lights to artificially create springtime. If you choose to do this you want the mare under lights 16 hours per day. This can be done with a timer and a 100 watt light bulb. Usually, having the light on from 4pm to midnight is adequate. This process should begin 4-6 weeks prior to breeding.
Ideally you will check the mare with ultrasound prior to breeding, particularly in the months of August and September to be sure that she is cycling and is not transitional. Mares that are not yet cycling will have small inactive ovaries and a 'quiet' uterus (a uterus unresponsive to estrogen and progesterone).
Mares go through a 'transition' period as they begin to cycle at normal intervals. During this transitional period, the mare may have inconsistent 'heat' cycles and inconsistent 'heat' behaviour. Mares are not generally fertile during the transition period, but can successfully respond to hormone therapy while in transition and then be bred.
Hormone therapy for mares has become a mainstay in the industry to make breeding more efficient, reducing costs and increasing fertility rates. The hormones most routinely used are Lutalyse (prostaglandin), Regu-Mate/Altreno (progesterone), HCG (human chorionic gonadotrophin), and Deslorelin (Ovuplant/Ovuprost).
OK, so your mare is ready - let's get started! You have selected a stallion. You want to ship semen to AI (artificially inseminate) your mare. We need to synchronize your mare for breeding during the mid-week to facilitate shipping and avoid weekend inconveniences and costs.
This would be the reasonable protocol for most circumstances: