The reproductive function of the breeding pigs is reduced (for example, the estrus is not obvious, the conception rate is reduced, the litter size is reduced, the fetus is weak, etc.), and the breeding disease of the breeding pig is prone to occur, which is difficult to find and control, lead to the number of sows that can be born by normal breeding is reduced. Since there is no certainty about the number of sows that are being pregnant, often forced to over-increasing the number of sows in order to compensate or avoid losses.

However, excessive childbirth often produce another result: not only will it increase management difficulties due to the destruction of balanced production, but also increase the reproductive function of sows and the occurrence of diseases, thus causing a vicious circle, seriously affecting productivity and economic efficiency. Due to the high accuracy of early diagnosis of color doppler ultrasound machine, if used for early monitoring of breeding, the exact number of sows for conception or infertility can be mastered very early, and the grasp of the number of breeding and controlling balanced production will be greatly increased.