estrous-cycle
US /ˈes.trəs ˌsaɪ.kəl/
UK /ˈiː.strəs ˌsaɪ.kəl/
名词
发情周期
the series of physical changes that a female animal repeatedly goes through, during which she becomes fertile (= able to become pregnant) and willing to mate (= have sex):
示例:
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Female llamas do not go into "heat" or have an estrous cycle.