1, physical condition is too fat or too thin: during pregnancy, a long time to the sow high level feeding, will increase the rate of sow stillbirth, because the sow eats too much will cause excessive physical condition hypertrophy, resulting in excessive fat deposition around the uterus, subcutaneous, peritoneum, sow is easy to fatigue during childbirth, the time spent to give birth is longer, the piglet birth mortality rate is high; but the body condition is too thin sow, due to insufficient productivity, uterine paroxysmal weakness, but also prone to prolonged labor, resulting in increased fetal death.
2. Eating too much before delivery: causing the sow to bear too much burden on the intestine during childbirth, compressing the uterus and birth canal, and prolonging the labor process during childbirth.
3. Constipation: due to constipation, gastrointestinal emptying is blocked for a long time, so that feces fill the intestine, compressing the birth canal, and the sow does not eat due to constipation for a long time, the physique is weak, the childbirth is weak, the sow is very easy to have difficult labor or prolonged labor, and stillbirth is more likely to occur.
4, summer high temperature: According to statistics, sows in the environmental temperature of higher in May to October to give birth to piglets, the piglet stillbirth rate is 0.3 to 0.4 heads higher than the average litter in the months with lower ambient temperature. In summer, due to high temperatures, sows are affected by heat stress and secrete too much stress hormone - adrenaline in the body. Epinephrine causes uterine vasoconstriction, thereby reducing the amount of oxytocin reaching the smooth muscles of the uterus, and the uterine muscles do not receive enough oxygen, causing the frequency and intensity of uterine contractions to decrease, resulting in a prolonged delivery time.
5. Newborn sows: because it is the first time to give birth, the stress is larger, often irritable, undecided, and the body will secrete a large amount of epinephrine, thereby inhibiting the number of oxytocin reaching the smooth muscles of the uterus, so that the delivery process is prolonged.
6. Reproductive disorders or general hyperthermia diseases: they will cause sows to stillbirth and prolong the labor process.
7. The fetus is too large or stillborn.
8. Mycotoxins: Mycotoxins damage the parenchymal organs, especially the damage to the liver and kidneys, affect energy supply, and affect productivity. F2 toxins can form rectal, soft-birth canal edema. Obstructing childbirth.
9, sow qi and blood deficiency, poor cardiopulmonary function: at present, sows generally lack of exercise, lifelong living in the limit bar, the only exercise is the rigid machinery in situ up and lying down, cardiopulmonary function can not be effective exercise, resulting in sow respiratory function is not perfect, gas exchange capacity declines, blood supply capacity is insufficient, while the lung capacity is low so that the sow breath holding force time is significantly shortened, insufficient physical strength; in addition, due to insufficient qi and blood, amniotic fluid secretion is small, dry birth canal, insufficient productivity, resulting in prolonged labor.
10, premature use of oxytocin: oxytocin promotes uterine rigid contraction, uterine contraction, resulting in severe pain in sows, causing sows to be overly tired, and late delivery weakness; if high-dose injection of oxytocin will lead to strong uterine contractions, spasms, piglets are more difficult to produce, and even fetuses and sows die; uterine contractions violently, resulting in rapid discharge of amniotic fluid, causing dry birth canals, increased resistance, and longer labor.