MARE HAIR' MANE is the term used to describe the long, thick hair that grows on the neck and head of a horse. It is usually much longer and thicker than the rest of the horse's coat, and is often groomed and styled for show horses. Mare hair is the term used to describe the shorter, thinner hair that grows on the body of a female horse. It is usually shorter and thinner than the MANE, and is not usually groomed or styled.