In general dairy farms, the embryo death rate of cows within 28-56d of pregnancy is 10% -16%. As the embryo implantation occurs more than 40 days after fertilization, the early pregnancy diagnosis made by B-ultrasound in cows at 30 days must be checked again at 60 days to finally determine pregnancy. Early embryonic death in high-yielding dairy cows exceeds 20%. The amount of embryo loss actually depends on various factors in the pasture, such as feed nutrition and quality, herd health and disease, stress and environment, etc. Therefore, basic research in these fields needs to be further strengthened to solve the problem of cow infertility.

The effect of B-ultrasound on the conception rate of cows

In some ranches, the comparison results of the conception rate data of adult cows show that the monthly average estrus conception rate of adult cows has increased by 3-6 percentage points, but the difference is not significant. This is because the increase in breeding rate does not correspond completely to the increase in conception rate. Generally, the average conception rate range of high-yield cows is about 40% -50%. The application of B-ultrasound early pregnancy diagnosis in cows is indirectly related to conception rate. If the monthly average estrus conception rate of cows can be increased by 3-6 percentage points during production, it will be very valuable for achieving annual reproductive indicators. From the comparison of conception rate data among young cattle, it can be concluded that the differences in conception rate among young cattle may be due to individual month breeding adjustments and calving distribution. For example, some ranches have a fertility rate of 100% during mating, but large-scale breeding work has not yet begun.