How to identify the estrus of sows

Proestrus: the vulva of sows begins to swell to the peak of swelling. At this time, the spirit is restless, chasing and climbing, and pressing his back with his hands is dishonest.

Mid-estrus: the swelling of the vulva begins to subside, showing micro-wrinkles, in a daze, frequent urination, standing still by pressing its back with hands, and white sticky fluid from the vagina, accepting boars to climb and allow mating.

Late estrus: swelling of the vulva, gradually subsiding until all subsided, and there is white frost. Do not allow boars to climb and mate.