Any female horse under 4 years is still considered a filly.
Before the age of 4 she is a filly on her 4th birthday she becomes a mare
3 years
2 years old and younger: Filly 2 years and older: mare When speaking of the mother of a foal, they are referred to as a dam.
1899 5 year old mare Imp then in 1904 3 year old filly Beldame
A mare is a mature female horse, usually over the age of four, while a filly is a young female horse, usually under the age of four. After a filly reaches four years old, she is typically referred to as a mare.
Newborn to four years old is a filly, five and up is a mare.
A mare if over 2 yrs old, a filly if under 2 yrs old.
A young mare under four years old is called a filly.
DOnt place a filly with other horses after being weaned. Maybe as a 2 year old, but dont make it a habit. only put a filly/mare out with others that were in their paddock when they were weaned. Introducing new mares can lead to vicious fights. And CERTAINLY NOT STALLIONS unless you want a foal and a paranoid mare. Geldings are ok but still try it sometimes, depending on the horse.
under two years old, a filly. over two years, a mare.
In general a filly is a female horse under 4 years of age. The related link below may help answer the question.
Filly: A female horse aged 5 years old or younger. Colt: A male horse aged 5 years old or younger.