Breeding cows are 15 to 18 weeks old and weigh about 370 kg to participate in breeding. The estrus performance of the cows was disturbed and the genitals swollen red, secreted mucus and accepted a crawl. Select high quality frozen sperm. Postpartum 40 to 60 days to observe the first heat after childbirth, timely breeding, postpartum 70 days without heat should be promptly checked and treated. Pregnant cows do not show estrus, and a few can have fake estrus. After pregnancy, the vaginal mucosa changes from pink to pale, and the amount of mucus increases and becomes thicker like a paste. The expected date of birth is “month minus 3, plus day 6â€, with an average of 280 days. Pregnant cows need to avoid colliding, slipping, whipping, sprinting and sharp turns. The symptoms of childbirth are breast enlargement, vulvar swelling, and frequent defecation. Disinfect the hindquarters and genitals of cows before laying calves, prepare grass mats and prepare for artificial midwifery. When the fetus's head is exposed, tear the amniotic membrane to break the water. After the yak is born, use a sterile towel to remove the mucus in the mouth and nostrils and cut off the umbilicus. Then use a bedding to wipe off the mucus from the bovine body, remove the soft hooves, and weigh in the pen.