Breeding season for horses is usually during the longer days of the year, so baby horses, or foals, have the advantage of mild weather. Feral horses breed successfully without human assistance. Human assistance is beneficial to domestic horses. Humans can increase the chances of a successful mating; a successful pregnancy, successful foaling and help the foal grow healthily.
For more information see the articles Horse breeding & Foal, see also further in this article
To attract a mate, the female horse, or mare, urinates, raising her tail and revealing her vulva. An interested male horse, or stallion, approaching with a high head and tail and ears drooped backwards, will nicker, nip and nudge her, as well as sniff her urine to determine her sexual maturity. This innate behavior stimulates the mare's secretion and the stallion's erection. If both the mare and stallion are satisfied with each other, he will mount her and copulation will occur. Often they will periodically repeat courtship and breeding while the mare continues to secrete estrogen.
Internal fertilization happens in the mare's fallopian tubes. An egg from the mare's ovary and sperm from the stallion's penis will meet slightly below the ovary. Once fertilized, the egg goes on to the uterus, taking about seven days and already dividing. Upon entering the uterus, the egg might have already reached the blastocyst stage.
The gestation period lasts for about eleven months. During the early days of pregnancy, the embryo, or fetus, is mobile, moving about in the uterus until a protective membrane surrounds it, making it stationary. A heartbeat can be detected on day 21, and the fetus gender can be determined by day 70 of the gestation. Initially, the fetus is pinpoint size. Halfway through gestation the fetus is the size of between a rabbit and a beagle. The most dramatic fetus development occurs in the latter trimesters.
Foaling normally takes place at night or early in the morning, and is generally over in 15 minutes. Once the foal comes out, the mare will chew on the membranes/placenta to prevent the foal from suffocating and lick the newborn foal to help blood circulation. In fifteen minutes, the foal will attempt to stand and get milk from its mother. A foal should stand and nurse within the first hour of life.
To create a bond with her foal, the mare licks the foal, enabling her to distinguish hers from others. Many mares are aggressive when protecting their foals, and may attack other horses or even humans that come near their newborns. Foals are typically weaned at 4-8 months of age, although in the wild a foal may nurse for a year. A filly (female) horse will begin to ovulate after a year or two, although most will be 3-4 before giving birth. Colts (males) reach sexual maturity at about 2-4 years old. The stallion has minimal parental investment in the foal, and may protect the general herd instead of his particular foal(s).
Domestic mares require specific care and nutrition to ensure that they and their foals are healthy. Mares are given Rhino shots (vaccinations against Rhinopneumonitis virus which can cause abortions) in months 3, 5, 7, 9, and 11 of their gestation periods.
Mares are often fed more than other horses because their bodies require extra nutrition to form and nurse a foal.
A special foaling stall or shed that is large and clutter free provides the mare with a safe place to give birth. While most horse births happen without complications, many owners have foaling kits prepared in case of a birthing emergency. After birth, a foal's navel is dipped in iodine to prevent infection and the newborn is monitored to ensure that it stands and nurses without difficulty.
Taken From Wikepidiea