How to Shorten the Farrowing Process in Sows? Practical Methods Shared
The stillbirths referred to here are normal individual fetuses that die during farrowing in sows - white fetuses. This does not include mummified and black fetuses formed in the early and mid-gestation stages. The main cause of stillbirths (white fetuses) in sows is that the farrowing process is too long. The normal farrowing process in sows (from the delivery of the first piglet to the complete expulsion of all afterbirth) is 2.5-3 hours. A farrowing time exceeding 3 hours is considered prolonged farrowing, and prolonged farrowing can lead to piglet death at birth. This is because during farrowing, placental contraction and impaired blood flow cause some piglets' placentas to detach and umbilical cords to break. Piglets with severed umbilical cords must be delivered within 5-10 minutes. If the farrowing process is prolonged due to various factors and piglets with severed umbilical cords are not delivered in time, the piglets will die from hypoxia. According to relevant statistics, deaths of piglets with severed umbilical cords caused by prolonged farrowing account for 80%-90% of all stillbirths.
Causes of prolonged farrowing in sows
1. The sow is too fat or too thin at farrowing. During gestation, feeding sows at a high level for an extended period increases the stillbirth rate, because overeating causes the sow to become too fat, leading to excessive fat deposition around the uterus, under the skin, and in the peritoneum. During farrowing, the sow tires easily, farrowing takes longer, and piglet mortality at birth is high. However, sows that are too thin also tend to have prolonged farrowing due to insufficient expulsive force and weak uterine contractions during farrowing, leading to increased fetal death.
2. The sow eats too much before farrowing, causing an excessive intestinal burden during farrowing, which presses on the fetuses and makes piglet delivery difficult, prolonging the farrowing process.
3. Hot summer weather makes sows prone to constipation. Due to constipation, gastrointestinal emptying is blocked for a long time, so feces fill the intestines and press on the birth canal, affecting fetal delivery. At the same time, because of long-term constipation the sow refuses to eat and becomes weak, with insufficient strength for farrowing. Sows are highly prone to dystocia or prolonged farrowing, and stillbirths are more likely to occur.
4. Due to the influence of high temperatures in summer, the farrowing process in sows is generally longer. According to statistics, piglets born to sows during the higher ambient temperature months of May to October have a stillbirth rate per litter that is on average 0.3-0.4 piglets higher than in months with lower ambient temperatures. The main reason is that high summer temperatures prolong the farrowing process in sows. In summer, due to high temperatures, sows are affected by heat stress and secrete excessive stress hormones - adrenaline. Adrenaline causes constriction of uterine blood vessels, thereby reducing the oxytocin reaching the uterine smooth muscle. The uterine muscle does not receive enough oxygen, causing a decrease in the frequency and intensity of uterine contractions and prolonging the farrowing time.
5. Some first-parity sows, because it is their first farrowing, experience greater stress, are often restless and unable to lie still, and also secrete large amounts of adrenaline, which inhibits the amount of oxytocin reaching the uterine smooth muscle and prolongs the farrowing process.
6. When sows are infected with reproductive disorder diseases or common high-fever diseases, stillbirths and prolonged farrowing can both occur.
Prevention and control measures
To reduce the stillbirth rate of piglets at farrowing, it is necessary to prevent prolonged farrowing in sows and shorten the farrowing time as much as possible. In production, strengthen feeding management with prevention as the priority.
1. Control the sow's body condition at farrowing and prevent it from being too fat or too thin. In practice, a sow at farrowing should have a full back with a flat top line, with no bones protruding. Below the lumbar vertebrae, behind the ribs and in front of the pelvis, there should be a depression; too-fat sows have no depression. Therefore, before day 98 of gestation, restricted feeding should be carried out according to the fetal growth and development pattern and the sow's body condition. From day 100 of gestation to 3 days before farrowing, the sow should be given full free access to feed. This can both increase piglet birth weight and prevent the sow from becoming too fat.
2. Sows must be feed-restricted before farrowing. To reduce the adverse effects of an excessive gastrointestinal burden on farrowing, feed restriction should begin 3 days before farrowing (based on the expected farrowing date). The feed restriction standards are: on the 3rd day before farrowing, 3 kg per sow per day; on the 2nd day before farrowing, 2 kg per sow per day; on the 1st day before farrowing, 1 kg per sow per day. At farrowing, no feed is given during the farrowing meal; feed 0.5 kg after half a day. For example, if the sow farrows in the morning, stop feeding in the morning and feed 0.5 kg in the afternoon; if she farrows in the afternoon, stop feeding in the afternoon. On the 1st day after farrowing, feed 0.5 kg in the morning and 0.5 kg in the afternoon; on the 2nd day after farrowing, 2 kg per sow per day; on the 3rd day after farrowing, 3 kg per sow per day; from the 4th day after farrowing to weaning, feed freely. That is, pre-farrowing feed restriction goes from more to less, and post-farrowing feed increase goes from less to more, to prevent postpartum indigestion in sows.
3. Prevent constipation before farrowing in sows. It is recommended that during the week before and after farrowing, 1% sodium sulfate and 0.5% rhubarb baking soda powder be mixed into the feed. This can make sow feces soft and moist and help promote smooth defecation. If conditions permit, pig farms can use Milqxit for better results.
4. In summer, strengthen heat prevention and cooling work for pregnant sows, especially sows in late gestation and sows about to farrow that have been moved onto the farrowing crates. Pregnant sows are kept in stalls with high density, making heat dissipation difficult. In particular, sows in late gestation eat more, and body heat increases after eating, with body temperature rising by about 0.5°C compared with before eating, reaching 39.5°C. When sows at 102-110 days of gestation maintain this temperature for a long time, the stillbirth rate of piglets at farrowing increases. Therefore, when the ambient temperature reaches above 30°C, it is recommended to mist pregnant sows in the breeding house at half-hour intervals for cooling, and to spray water on sows about to farrow in the farrowing house for cooling, so as to minimize the impact of heat stress on sows.
5. For farrowing houses where sows are actively giving birth, keep the house as quiet as possible, especially for first-parity sows. When a sow is restless, massaging the udder can calm her down, which is very meaningful for promoting smooth farrowing.
6. After piglets are born, wipe off the mucus, dry the hair coat, and immediately place them beside the sow's udder to suckle. Continuous suckling by piglets stimulates the sow's hypothalamus to secrete oxytocin, causing uterine contractions. This not only helps smooth farrowing and shortens the farrowing process, but also helps milk let-down.
7. Do a good job of vaccination to prevent reproductive disorder diseases in sows, and promptly treat sick pigs, especially sows with fever.
Correct use of oxytocin
For prolonged farrowing caused by various reasons, the problem can be solved through the correct use of oxytocin.
1. During the farrowing process, when piglets are being delivered smoothly (1 piglet delivered within 10 minutes), do not use oxytocin. However, when the next piglet has still not been delivered after an interval of 30 minutes, it is recommended to immediately inject 10 international units of oxytocin to assist farrowing. If the piglet is still not delivered within 20 minutes after the oxytocin injection, check whether the sow has dystocia so that assistance can be given in time.
2. Four points to note when using oxytocin
① It is contraindicated for sows whose cervix has not opened (that is, the first piglet has not been delivered).
② It is contraindicated for sows with dystocia, such as narrow pelvis or narrow birth canal.
③ Do not use excessively: during the farrowing process, a single injection dose must not exceed 10 international units. High-dose oxytocin injection will cause severe uterine contractions and spasms, making piglets even harder to deliver and causing death. Postpartum uterine fatigue and functional paralysis can easily cause retained afterbirth and lead to metritis.
④ After farrowing is completed, injecting 3-4 international units of oxytocin into the sow helps completely expel the placenta and lochia, thereby reducing the occurrence of metritis.