Animal production in general terms can be diverse depending on the objective of the species; However, each of them needs to be reproduced so that it can be perpetuated with greater impact over time.

When we talk about horses we involve a series of parameters that we must know to guide us on the path of how to manage them in order to obtain the best benefits from them; Taking into account that there are a great variety of sports disciplines in different countries, and depending on their objectives, various strategies can be applied.

When referring to the development of a species, we must always start from the nature of the animal, that is, we know what its behavior is like in its optimal state and know what its basic needs are in order to grow and reproduce. The latter, with the aim that when we want to study the species in depth, we can understand the reason for its behaviors.


In horse breeding, management is a fundamental pillar to guarantee success. Now, when we talk about management we mean controlling in the best way the factors that directly influence the health of the animal.

For a horse to express 100% of its genetic material, it needs to be accompanied by an environment that provides its essential requirements; such as, for example, covering the basic nutritional needs to fulfill the physiological functions that the animal requires in order to develop and reproduce.

It is vitally important to carry out reproductive control and monitoring of the mares destined for breeding, in order to guarantee positive results every year. As commented by Brinsko et al., 2010, the gestation period in mares is 335 to 342 days, mentioning that around day 305 of gestation viable foals can be born or in some cases not viable, in addition to this, it mentions that for some authors, the expulsion of the fetus before day 300 is considered an abortion and that between days 300 and 320 they would be called premature foals, which indicates the importance of caring for a pregnancy until delivery, which, in certain mares, the gestation time It can reach up to 360 days (p. 114-115).

In the management of horse breeding there are other important points to address, such as avoiding stressful situations in the animals; the consumption of any toxic substance, since this would have serious consequences, and carry out vaccination control for the entire herd and the appropriate one for pregnant mares.

Reproductive activity and sexual behavior in the mating season

Mares are animals that have a reproductive cycle that is directly influenced by the amount of light they receive in a day (photoperiod); that is, for the long days. In this sense, the ability to have several reproductive cycles in certain seasons or environmental seasons of the year is called seasonal polyestry.

Due to this behavior, equine reproduction is carried out in certain months of the year, which is called the Riding Season, which will be the months where there is the greatest amount of sunlight. This Season will basically occur in the first 6 months of the year in countries located in the northern hemisphere of the earth and in the second half of the year in countries in the southern hemisphere.

According to Aurich, C (2011), during said Riding Season, which would be in spring and summer, the average duration of the mare’s estrous cycle is an average of 22 days, with 5-7 days of estrus (a stage that accepts the male). On the other hand, in young females, puberty occurs around the age of 12-18 months, also being influenced by the time of year. Animals born in early spring will not reach puberty before the same time the following year (p. 220-221).

The behavior of a mare will be closely linked to her estrous cycle, as mentioned in Crowell-Davis, S.L., 2007. Females will be receptive to males on the days of heat (on average 5-7 days of estrus), showing a passivity at the time of mating. be in front of him. The opposite happens when these days of estrus end, where the mare will show aggression towards the breeder, wanting to bite him, kick him, in order to get him away (p. 12-17).

To know the exact cycle of a mare, we can calculate it taking into account the interval of days between two ovulations.

It is important to mention that the sexual behavior of the reproductive male remains active throughout the year. And the moment of mounting is preceded by a series of acts where he imposes his strength and elegance to court the female.

Mechanism of action due to Photoperiod

Now, to understand the meaning of the effect of luminosity on the mare’s cycle, we take an explanation according to Brinsko et al, 2010, where it shows us that by increasing the amount of light perceived by the retina (inner membrane of the eye) by the mare, it sends signals that are captured by the pineal gland, which generates a decrease in the secretion of the hormone melatonin, causing a positive response to the hypothalamus to secrete GnRH (gonadotropin-releasing hormone) and this, in turn, produces the release of the hormones FSH and LH by the pituitary gland. These last two hormones mentioned are responsible for the start of ovarian activity for the subsequent ovulation (p. 11).


In tropical countries like ours, where the environmental seasons are not so marked, we can find estrous cycles throughout the year. This allows us to be able to reproduce our animals continuously, however, we can find, in addition to the environmental factor, other factors that generate challenges for us to carry out equine reproduction.

It is important to mention that there are horse breed associations that are governed by the Riding Seasons; to establish the ages of the animals, with the aim of classifying them into categories according to their calendar ages.

For example, in the Thoroughbred Racing all horses born in the first 6 months of the year will be classified as one year old from January 1st in the northern hemisphere; while in the southern hemisphere, animals born in the second half of the year will be considered a yearling from July 1st.

Unlike the Colombian Creole breed, which is not subject to a Breeding Season so reproduction can be worked on; throughout the year and the horses will be classified according to their ages by month to group them into competition categories.

Veterinarian Eduardo Prado Carroz

University of Zulia, Faculty of Veterinary Sciences (FCV)

Member of the College of Veterinary Doctors of the state of Zulia, no. 2483

For anyone who may be interested, you can contact us through social networks, on Instagram as @espacio_equino