The sow is in heat. The reason why sows still bark after frozen semen is released is that sows need to mate with estrus boars to meet their physiological needs. Even after the release of frozen semen, sows will continue to be in estrus, so they will still show barking and other behaviors. Frozen semen is a kind of semen preserved at low temperature, which can maintain the vitality and fertilization ability of semen to a certain extent. The frozen semen has good quality and preservation conditions, and can still be fertilized successfully after being put into the sow, even if the sow barks, it will not affect the fertilization result.