From the effect of B-ultrasound on the breeding rate to the manifestation of reproductive rate, there are direct effects of B-ultrasound on cattle, as well as indirect effects, which are reflected in the increase in the number of breedings and the number of pregnancies. Some statistics show that the total reproductive rate of adult cows has increased by 5.1-7.6 percentage points. Of course, the impact on reproductive rate also includes comprehensive management factors, such as embryo loss, fetal vitality and culling rate. Some studies have found that the application of B-ultrasound technology for cattle has little effect on the reproductive rate of young cattle. With the high cost of dairy cow breeding, empty-stomach feeding is even more worrying. In the south, dairy cow breeding is mostly concentrated from December to May of the following year. Due to the influence of the high temperature and high humidity in the south, breeding work is passively waiting for about half a year. During this period, the proportion of empty-stomach feeding is very large. The daily cost of raising high-yield dairy cows in large-scale ranches in developed dairy areas in the south is about 50-65 yuan. If the reproduction rate can be increased by 5% in a ranch with 1,000 adult cows, it means that the average participating cows in the year can save an estrus cycle, that is, 21 days. According to 500 adult cows, it is calculated as: 5OO*21*50=525,000 yuan. Saving the breeding cost is the economic value created by the improvement of breeding efficiency.

Concentrate on B-ultrasound early pregnancy examination for cattle 30 days after breeding, and find out empty-stomach cows in time, so that the 60-day direct inspection empty fetus rate is 4.92%, which is 25 percentage points lower than the 60-day direct inspection empty fetus rate, which greatly improves the efficiency and reliability of rectal examination. The 4.92% empty fetus rate is due to the difference in the use of B-ultrasound in cattle before and after, which is within the range of early embryo mortality. Basically, this can be considered as the difference caused by early embryo death. Some people have reported that the difference in the empty fetus rate before and after B-ultrasound in cattle is 5.89%.