Estrus Cycle and Its Performance in Pigs

After the sow reaches sexual maturity, there will be an inherent cycle of sexual activity, also known as the estrous cycle. The average estrous cycle of sows is 21 days, ranging from 19 to 24 days.

The performance of sows in estrus: the cycle of estrus distributes proestrus, estrus, metestrus. Sows have some physiological and behavioral manifestations 24 hours before estrus. There are generally seven common signs of estrus: restlessness, climbing across other sows, poor appetite, watery mucus flowing from the vulva, biting the fence, and often humming. The vulva becomes red and swollen.