Reproduction is one of the main functions of dairy cows and a key link in dairy cow production. The purpose of running a good dairy farm is: first, to make profits by producing more dairy cows; second, to increase value and expand the herd. To achieve the above goals, it is necessary to have a high level of breeding performance as a basis, and high-level breeding management is inseparable from scientific breeding management.

The average empty days of adult cows refers to the period from calving to the next pregnancy of dairy cows, between 80 and 100 days. The reproductive system of dairy cows has recovered normally and is ready for the next pregnancy; the average days of the first estrus after calving refers to the estrus of dairy cows within 40 days of calving. If it is longer than this number of days, it is necessary to use veterinary B-ultrasound to check the condition of the cows in time.

Monthly breeding rate of non-pregnant cows >60 days after calving Monthly pregnancy rate of non-pregnant cows >60 days after calving means that 80% of the cows with more than 60 days after calving should be bred each month, and the number of pregnant cows should account for 42-52% of the total number of breedings; the average number of days for the first breeding after calving means that the cows should be bred once within 40-60 days after calving. Breeding cows in this time period indicates that the uterus of the cows on this ranch has recovered well after calving. The pregnancy rate of less than 3 breedings means that the number of cows that are pregnant within 3 breedings after calving accounts for the number of cows bred within 3 breedings; the estrus interval of 18-24 days refers to the time from the current estrus to the next estrus of the cow. In this time period, it indirectly indicates that the health of the cows on this ranch is good.

Standardized management of dairy cows is very necessary for dairy farms. The effective use of veterinary B-ultrasound technology in the breeding process of dairy cows is a very important task. The correct use of veterinary B-ultrasound can improve the reproduction rate of dairy cows.