Breeding Season: Choosing The Right Month For Your Mare

Jessica McDaniel
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Factors To Consider – What Is The Best Month To Breed A Horse

Breeding horses should be based on age, reproductive health, body condition and season. The breeding season for horses varies for each geographic area depending on climate.

When choosing to breed a mare, your first consideration should be her age. The best time to breed a mare will be between the ages of 4 and 12 years old. The best breeding age is between 6 and 9 years old. A mare younger than the recommended age may not have been exposed to the correct amount of hormones needed to develop various reproductive health conditions.

When breeding horses during the spring and summer, it’s important to consider availability of pasture and/or hay for feeding. Breeding mares may have an increased need for feed, and especially energy, during the winter months.

Mares should be kept dry with a comparatively high energy hay before and during breeding season. Mare owners should not push mares to breed during the summer months, so they are not in competition with their needs for water because of the hot summer weather. A mare that is in good health, not overweight, and provided with plenty of feed should be able to carry a normal sized pregnancy.

Mare owners should take into consideration the reproductive health of the breeding mare. When breeding mares, they are not advised to breed early at all. As a matter of fact, early breeding can actually scramble the developing eggs and stop the embryo from growing.


In the west, breeding season for horses runs from late spring until early fall. It doesn’t allow much time to breed a foal before the mother must go into winter survival mode with reduced feed availability and limited calories. Pay close attention to how much breed time you have left before this switch occurs. If you don’t need a new foal until the following spring, you could delay breeding until mid to late summer.

The safest time to breed your mare is during the spring months of March, April or May, when nights remain consistently above freezing. Try to avoid breeding when we approach the summertime, as you are increasing your risk of a foal born too early or something going wrong during foaling.


How did a black stallion, foaled again?

In the past, plenty of breeders used breeding methods to manipulate foal colors. The use of black as a predominant color in breeding has been made possible by crossing a black stallion on a colored mare.

The first-cross offspring of a stallion and a mare whose colors are incompatible possess the same shade of color on the body as does a heterozygous individual of the same colors on the body as does a heterozygous individual of the same colors when bred with a homozygous one, but in the second cross one gets the homozygous color. In breeding practice, the animal whose color is wanted is mated to a homozygous individual having the color in question in the second cross.

While the theory is that one should mate the black stallion on a colored mare to get the desired outcome, this is not what has actually been happening. In modern times, artificial insemination has been done. We have a black stallion that has a colored foal that has also been bred to a colored mare and has another male graycolored foal.

Natural Cycle

Vs. Artificial Insemination

Did you know that there are two different methods you can use to breed your mare? If you are not familiar with breeding horses, the choices may seem very confusing, but after you learn the reasons an choosing a method can help you make a successful breeding plan for your mare.

Natural Cycle

A natural cycle breeding means timing the breeding by the mares heat (estrus). Estrous cycle is the monthly cycle the female mare experiences before they have their first heat. This cycle is very regular for mares beginning breeding at 2 years of age (the age of puberty) and it will continue every 28 days or so until they are 8 years old.

The Breeding Season

The most fertile time of the year begins in December and ends with the spring breeding season. The breeding season continues through April-May depending on the area of the country and the breeding season of the stallion. During this time is when many breedings are done, and it is a time when mares are bred every week or two.

The reason for breeding during this season is to take advantage of the biggest drop in temperature in the fall that will help keep the sperm alive longer. This is very important because sperm can live for three weeks, and if the mare is not bred at a certain time, she will stop coming into season.

Booking Requirements

It's important to choose the right month to book your mare in foal to avoid being caught out with no options. Equine breeders might be limited to certain seasons. Seasons could be dictated by the breed you are breeding for. As an example, many thoroughbred studs will only breed from November to February because of the weather. Also, breeders tend to book their mares at least 12 months prior to breeding, so book early to avoid being turned away at the door.

Certain seasons are also more popular than others: As an example, breeders may be booked out for fawns in the spring months.

Laying aside both financial and calendar concerns, should you prefer to breed your mare at a certain time of the year?

If you ask an expert this may be their reply: "It's completely up to you when you choose to breed your mare. It's entirely based on your calendar and your choice. Seasonally, for a healthy foal, it is best to breed in the spring time. The winter season could be troublesome, but it's all about the variety."

Final Words – What is the Best Month to Breed a Horse

If you are planning to breed your mare, there will always be conflicting advice on the best time to breed horses. Horses are seasonal breeders and nature puts them under many constraints. Your mare’s conception date has a lot to do with her health, this makes breeding for it's success is not an easy task.

However, there are a few things you can do to improve your odds of conceiving a healthy foal and uncooperative weather/hormones shouldn't be an all together bad experience.

There is a debate whether or not horses should be bred in the spring or fall. Some experts suggest that fall breeding is healthier for the horse while others argue that spring breeding is better.

The Fall Fertility Index, which tells you what the conception rate should be, has been calibrated for horses bred in the Fall because breeding in the fall has the greatest odds of success. This is due to the fact that conception rates usually drop as the weather warms up.

In the horse's natural environment, fertilization normally occurs while they are still in their Winter coats which are long and dense. When temperatures rise, mares shed their winter coat so they can cool off, causing conception rates to drop.