Generally speaking, the end of estrus of sows is the best time for breeding. The cost of missing a sow in estrus is very high. In addition to the cost of feed, there are also labor costs. Therefore, estrus identification is very important. The following methods are usually used to identify sow estrus:
 
The first is the identification method of vulva changes. When sows are in estrus, the vulva is obviously congested and swollen. With the arrival of the peak of estrus, the mucosa inside the labia turns light red or blood red, and the amount of mucus is large and thin. Then the sow's vulva turns light red, slightly wrinkled, and slightly dry. The blood redness of the mucosa inside the labia begins to decrease, and the mucus changes from thin to thick. At this time, the sow enters the end of estrus, which is the best time for breeding.
 
The second is the mounting identification method. When the sow is in estrus to a certain extent, it not only accepts boars to mount, but also is willing to accept other sows to mount, and even actively mounts other sows. When testing the estrus with a boar, the sow will be extremely excited and will sniff head to head; when the boar climbs on her waist and back, if she stands still, this is a good time for breeding.
 
The third is the pressing identification method. Press the waist and back of the sow with your hands. If the sow does not hum or cry after pressing, but stands still with her limbs spread apart and her waist arched, this is the most active stage of estrus for the sow, and it is also a good time for breeding.