A young male horse is referred to as a colt horse. Although it is often called a foal, this terminology is incorrect. A foal is any horse, either male or female, that is a year old or younger. The owner of a domesticated colt horse may choose to castrate him, making the horse a gelding. Colts that are not castrated are referred to as stallions or full horses, and they are often used for breeding.
Depending on the part of the world, for a male horse to be called a colt horse it is usually under the age of four. In other parts of the world, however, a colt can be a different age. For example, in Britain, a male horse that is younger than five is considered to be a colt horse.
To be called a gelding, a domesticated colt horse is castrated. This is typically a surgical procedure in which the horse loses the function of its testicles, rendering it unable to breed. In most parts of the world, the majority of male horses are castrated. In some parts of the Middle East though, male horses are still not castrated.
There are a couple reasons for castrating a colt horse. One involves breeding. Most of the lesser quality colts are castrated to prevent tainting the gene pool. By preventing these horses from breeding, owners ensure that only the best traits are passed on to the next generation of horses, resulting in high quality, strong, and sought-after animals.
Geldings are also generally much better behaved and easier to handle than stallions. They are often used in horse shows and for riding. Although mares are also used for these purposes, these female horses are generally much more easily agitated, especially when in heat.
The time of castration can vary. Many owners believe that the best time to castrate a colt horse is before it reaches sexual maturity. Stallions that have been used for breeding, called stud horses, on the other hand, are typically castrated much later on in life. When a stallion can no longer be used to breed, due to sterility or old age, it may then be castrated to ensure that it is easier to handle.
In a herd of wild horses, or mustangs, there is usually only one lead stallion. At around one or two years of age, a colt horse is typically driven from the herd by the main stallion. When this happens, he will often join a herd of young stallions and other young colt horses, called a bachelor herd.
When he is ready and mature enough, he will usually try to form his own herd, made up of mostly mares. In order to do this, some colts will challenge the lead stallion of a herd. Sometimes, he can attract at least one or possibly more young mares to start his own new mustang herd.