Repeated infertility in dairy cows refers to a disease in which the sexual cycle of dairy cows is normal or basically normal, the reproductive system is clinically normal, and the cows are not pregnant after mating for 2 or more times. The incidence rate accounts for about 20% of dairy cows. Due to its unclear clinical symptoms and complex etiology, the treatment effect is often poor. Some dairy cows are forced to be eliminated after mating due to long-term infertility. The elimination rate accounts for 35% of reproductive diseases, causing great economic losses to dairy farms. It is necessary to regularly use cattle B-ultrasound to check the condition of dairy cows.

Causes and symptoms There are many factors that cause repeated infertility in dairy cows, such as environment, feeding management, estrus identification, mating technology, overwork or excessive lactation, diseases of dairy cows' reproductive organs or other organs, which will directly or indirectly affect dairy cows' estrus, ovulation and embryonic development, and then lead to infertility, causing harm to dairy cow production and seriously affecting the development of the dairy industry. Regular use of cattle B-ultrasound examination is a necessary work for cattle farms. There are many types of infertility and the causes are complicated. Now we mainly introduce two types.

Ovulation disorder in cows Ovulation disorder, also known as anovulation, is one of the main causes of infertility in dairy cows, including anovulation and delayed ovulation. The ovulation status of the ovaries can be clearly seen on the cow B-ultrasound. Ovulation disorder is caused by abnormal gonadal axis. The hypothalamus-pituitary-ovarian gonadal axis regulates follicle development and ovulation, so any abnormality in the gonadal axis can cause ovulation disorder

Early embryonic death Early embryonic death refers to embryonic death caused by 10-35 days after mating of dairy cows. According to statistics, infertility caused by early embryonic death accounts for about 15% of infertile cows, which has a certain impact on the conception rate. The condition of the embryo can also be well seen through cow B-ultrasound. Clinically, it manifests as irregular estrus, and sometimes it manifests as turbidity of the carrier fluid during estrus. There are many factors that cause early embryonic death, such as potential abnormalities in the process of gametogenesis, intrinsic defects of the embryo, failure of maternal embryo recognition, abnormal maternal environment, etc., so it is necessary to use cow B-ultrasound examination frequently.

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