A cow's estrus cycle averages 21 days.

母牛的发情周期平均为21天。

A cow 's estrus cycle averages 21 days.

母牛的发情周期平均为21天。

An estrus is not a disease but a sign of a variety of conditions.

乏情不是一种疾病，而是一种多方面的体态迹象。

Anestrus (absence of estrus) is not a disease but a sign of a variety of conditions.

乏情不是一种疾病，而是一种多方面的体态迹象。

The number of the CEC was the most at estrus and remarkably (P<0.01) more than that of other stages.

角化上皮细胞在发情期数目最多，明显（P<0.01）高于其它各期；