Estrous cycle
type of ovulation cycle
The estrous cycle (US-EN; ) or oestrous cycle (UK-EN; ) (from Latin oestrus 'frenzy', originally from Ancient Greek οἶστρος (oîstros) 'gadfly') 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 phases, otherwise known as "rest" phases, or by pregnancies. Typically, estrous cycles repeat until death. These cycles are widely variable in duration and frequency depending on the species. Some animals may display bloody vaginal discharge, often mistaken for menstruation.
Many mammals used in commercial agriculture, such as cattle and sheep, may have their estrous cycles artificially controlled with hormonal medications for optimum productivity. The male equivalent, seen primarily in ruminants, is called rut.
Etymology and nomenclature
In British English, the spelling is oestrous cycle and oestrus, or (rarely) œstrus. In all English spellings, the noun ends in -us and the adjective in -ous. Thus in Modern International English, a mammal may be described as "in [o]estrus" when it is in that particular part of the [o]estrous-cycle.
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This entry incorporates text from “Estrous cycle” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.