1. Signs of childbirth
(1) Udder After 4 months of pregnancy in the newborn cow, the breast begins to enlarge, and the breast enlarges rapidly in the later stage; the breast development changes significantly 15 to 30 days before the birth of the cow, and edema occurs about 15 days before delivery. About 2 days before delivery, the breasts are extremely swollen, the skin is red, the nipples are full, and the colostrum can be expressed.
(2) Cervix and vulva The cervix begins to become enlarged and soft about 1 to 2 days before childbirth, the uterine plug softens into the vagina, sometimes hanging in the vagina outside the translucent cord; the vaginal wall is soft, the vaginal mucosa is flushed, the mucus gradually changes from thick and viscous to thin and lubricated; the labia are soft, swollen and enlarged about 1 week before delivery, and the folds on the skin of the labia are flattened and the skin becomes slightly rosy.
(3) Pelvic ligament At the end of pregnancy, the pelvic ligament of cows becomes soft and relaxed, especially 7 to 10 days before childbirth, it begins to soften significantly, and the buttock muscles appear obviously collapsed. 24 to 48 hours before birth, the sides of the oxtail root are concave.
(4) Behavior and body temperature When approaching delivery, the cow has difficulty moving, standing restlessly, rearing its tail, often making a excretory posture, decreasing or stopping appetite; the body temperature gradually rises 4 weeks before delivery, reaching 39.0 to 39.5 °C 7 to 8 days before delivery, but decreasing by 0.4 to 0.8 °C by 12 to 15 hours before delivery.
2. The process of childbirth
The entire delivery process is divided into three periods: the opening period, the fetal production period and the fetal coat discharge period.
(1) Opening period It generally takes 2 to 6 hours from the beginning of the uterus to the full opening of the cervix. At this time, the cow is uneasy, happy, abdominal pain, short labor pain, 15 to 30s, long interval time, about 15min. As the delivery progresses, its labor pains intensify and small twirls appear in the abdomen.
(2) Fetal production period From the full opening of the cervix until the fetus is excreted. At this point, both the contraction and the blame will appear. Nudge is the main motivation to expel the fetus. Cows show irritability, abdominal pain, rapid breathing, and a fast pulse. The cattle lie on their own after the appearance of the nuigatorium, and the gray-white or yellow amniotic sac composed of amnioidium-chorionic membrane is exposed to the pubic gate, and then the amniotic sac ruptures, and the grayish white or light yellow amniotic fluid is discharged with the fetus. Some amniotic sacs rupture first and flow out of the amniotic fluid, and then excrete the fetus. In general, the urocyst ruptures and discharges allantoic fluid during the fetal coat excretion period. The fetal production period of cattle is 0.5 to 4 hours.
(3) Tire coat discharge period From the birth of the calf to the complete discharge of the tire coat. After the birth of the calf, the cow quiets down, rests for a few minutes, the uterus returns to contraction, accompanied by mild intractoria, prompting the placenta to detach from the mother, and finally all the membranes, umbilical cords and part of the residual fetal water are discharged from the body. The discharge period of the tire coat is 2 to 8 h, and those who have not been discharged or exhausted after 12 hours are treated according to the tire coat.