False estrus in ewes means that the ewes have not ovulated, and the reproductive organs of the ewes have not shown the changes that should be seen in estrus, but in terms of behavior, they show acceptance of male ewes to mount or mount other ewes, and have tail wagging. When using a vaginal opener to examine the vagina of ewes with false estrus, it can be found that the vagina of the ewes with false estrus is dry and pale, the neck is closed, and sometimes there is white mucus blocking the neck (also known as uterine plug). When the sheep are examined with B-ultrasound, there are no mature follicles formed on the ovaries, so B-ultrasound in sheep is very useful for identifying false estrus. Ewes with false estrus cannot be bred.

Sheep B-ultrasound

A large proportion of ewes with false estrus are abnormal phenomena that occur after the ewes are pregnant. In this case, it is best to perform a sheep B-ultrasound examination after the ewes are pregnant. The main reason is due to reproductive hormone secretion disorders, insufficient progesterone, and excessive estrogen. When the progesterone level is higher than the estrogen level, estrus is not shown, and vice versa. However, after the ewe becomes pregnant, the female hormone cannot be secreted continuously and at high levels like when the ewe is empty-sleeved during mating, so the estrus is shorter and very irregular. If the sheep are not examined by B-ultrasound and the breeding is forced without distinction, artificial abortion often occurs due to uterine strain. If the estrogen level is high and lasts for a long time, early hormonal abortion may occur due to hormone imbalance. In addition, some false estrus phenomena are not caused by the sheep, but by feeding management and human misjudgment. For example, in summer and autumn, mosquito and fly bites cause the ewe to wag its tail constantly, which gives people the illusion that the ewe is in estrus. In fact, it is easy to identify by observing whether the ram is willing to mount and checking the changes in the ewe's reproductive tract, or it is also easy to know this phenomenon by B-ultrasound examination of sheep.

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