Anestrus and Diestrum

Anestrus noun - Applies to nonhuman mammals: a state or interval of sexual inactivity between two periods of estrus.

Diestrum and anestrus are semantically related. In some cases you can replace term "Diestrum" with "Anestrus", this nouns are similar.

Diestrum noun - (of animals having several estrous cycles in one breeding season) a state or interval of sexual inactivity or quiescence between periods of activity.

Anestrus and diestrum are semantically related. You can use "Anestrus" instead a noun "Diestrum".