A filly is a
female
An organism's sex is female ( symbol: ♀) if it produces the ovum (egg cell), the type of gamete (sex cell) that fuses with the male gamete (sperm cell) during sexual reproduction.
A female has larger gametes than a male. Females and ...
horse
The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 mi ...
that is too young to be called a
mare
A mare is an adult female horse or other equidae, equine. In most cases, a mare is a female horse over the age of three, and a filly is a female horse three and younger. In Thoroughbred horse racing, a mare is defined as a female horse more th ...
. There are two specific definitions in use:
*In most cases, a ''filly'' is a female horse under four years old.
*In some nations, such as the
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...
and the
United States
The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
, the world of
horse racing
Horse racing is an equestrian performance activity, typically involving two or more horses ridden by jockeys (or sometimes driven without riders) over a set distance for competition. It is one of the most ancient of all sports, as its bas ...
sets the cutoff age for fillies as five.
Fillies are
sexually mature
Sexual maturity is the capability of an organism to reproduce. In humans, it is related to both puberty and adulthood. ''Puberty'' is the biological process of sexual maturation, while ''adulthood'', the condition of being socially recognized as ...
by two and are sometimes bred at that age, but generally, they should not be bred until they themselves have stopped growing, usually by four or five.
[Ensminger, M. E. ''Horses and Horsemanship: Animal Agriculture Series.'' Sixth Edition. Interstate Publishers, 1990. p. 149-150] Some fillies may exhibit
estrus
The estrous cycle (, originally ) is a set of recurring physiological changes induced by reproductive hormones in females of mammalian subclass Theria. Estrous cycles start after sexual maturity in females and are interrupted by anestrous phas ...
as
yearlings.
The equivalent term for a male is a
colt. When horses of either sex are less than one year, they are referred to as
foal
A foal is an equine up to one year old; this term is used mainly for horses, but can be used for donkeys. More specific terms are colt (horse), colt for a male foal and filly for a female foal, and are used until the horse is three or four. Whe ...
s.
Horses of either sex between one and two years old may be called yearlings.
See also
*
Filly Triple Crown
The Triple Tiara of Thoroughbred Racing, formerly known as the Filly Triple Crown, is a set of three horse races in the United States which is open to three-year-old fillies. Presently the only official Triple Tiara is the three race series in N ...
*
Weanling
A weanling or weaner is an animal that has been weaned, eats solid food independently, and no longer relies on its mother's milk for nutrients. ''Weanling'' usually refers to a horse, though can be used with any livestock. ''Weaner'' is more co ...
References
{{Reflist
Types of horse
Female horses
Horse racing terminology