Key Points for Feeding and Management of Pregnant Sows in Hot Summer
Pregnant sows hold an extremely important position on a pig farm and can be said to be the lifeline of production. If a spell of intense heat comes after the summer solstice and management is poor, stillbirths or miscarriages may occur, causing heavy losses; if feeding and management are good and heat relief and cooling are effective, two goals are achieved at once, as pregnant sows can safely get through the summer and farrow, while the farm's litter size increases, reproduction expands, and economic benefits improve.
????Why Pregnant Sows Miscarry
Heat stress caused by high temperatures seriously affects the conception rate, embryo mortality rate, and miscarriage rate of sows. When pregnant sows are harmed by heat stress, the fertilized eggs have not yet formed a placenta in the early stage of uterine attachment and lack protection. The first 20 days of gestation and the last 30 days of gestation are both dangerous periods for stillbirth and miscarriage in pregnant sows, and the most dangerous period is within 18 days after mating. During the first 8 days of early gestation and from 11 to 20 days during embryo attachment, sows are most afraid of heat; even only 24 hours of high heat can cause early embryo death, and after 100 days of gestation they enter a sensitive period in which they are most afraid of heat. Because gestation is exposed to long-term heat radiation and high-temperature conduction stimulation, the sow's body temperature rises, and even the thermoregulatory center finds it difficult to maintain her own heat balance, causing a series of pathological changes in the sow's physiology. This heat stress thereby inhibits the secretion of luteinizing hormone and reduces progesterone secretion, ultimately leading to miscarriage in sows.
????Create a Cool and Comfortable Feeding Environment
After the Start of Summer the weather is hot, so the pig house roof should use materials with good insulation performance, such as straw curtains, to block the sun's heat radiation and keep the pig house cool. At noon when the temperature is above 30°C, water can be sprayed on the roof to cool it. In addition to opening the north and south doors and windows for ventilation, exhaust fans can be used to increase air convection, which can carry away heat from the pigs' bodies and make the pigs feel cool. When necessary, use cold water spray cooling or evaporative cooling pads. When the house temperature reaches above 35°C, cold water can be used to shower the pigs' bodies, and brushing the pigs' bodies can also be combined with this. When it is even hotter, the frequency of showering and brushing the pigs' bodies should be increased to keep the sow's body from overheating.
Plant more trees and grass in the pig farm to cover the ground and form a cool microclimate environment. Manure should be removed frequently from the pig house, which both eliminates pollution and keeps the pig house sanitary, so as to prevent fermentation from producing heat and raising the house temperature.
????Do a Good Job in Feeding Pregnant Sows
When feeding pregnant sows in hot weather, attention should be focused on the first 8 days of gestation. This stage is when the fertilized eggs implant and the placenta forms, so the protection of embryo development and prevention of miscarriage should be emphasized. Within 20 days of gestation and within 30 days before farrowing, nutrition should be strengthened and the nutritional level raised, and the nutritional needs for protein, vitamins, minerals, and trace elements should be met. In the late stage of gestation, not only nutritional needs but also quantity requirements must be met, and more concentrated feed should be added to meet the needs of rapid fetal growth and increase birth weight. In hot weather sows do not like to eat feed, so feeding time can be reasonably arranged and the number of feedings increased to raise feed intake. In addition to normal feeding, in the early morning and evening when the temperature drops, while the pigs are willing to eat, the amount fed should be appropriately increased, and more than 65% of the whole day's feed amount can be fed.
At the same time, feed more green feed containing less fiber, and do not feed roughage containing much fiber or feeds such as rice bran, so as to avoid increasing the pig's body heat. When energy is insufficient, 3% to 5% oil or fat can be added, which has the effect of high heat energy and little heat increase, both increasing energy feed and reducing heat stress.
In summer when the weather is hot, pigs drink a large amount of water, so a large supply should be provided for free drinking to meet their needs; drinking cold water is cooling and helps feed digestion. Especially in late gestation, eliminate mechanical stimulation and prevent slipping, falling, crowding, running, and jumping. Never hit pigs, chase them, or startle them, so as to avoid miscarriage. To ensure normal fetal development and avoid fetal absorption, stillbirth, or miscarriage, one injection of 2 ml progesterone should be given within 2 days after mating, which can effectively ensure the fetal survival rate. For sows with a history of chronic miscarriage, after pregnancy, 2 months later, progesterone injection can be given intramuscularly once every other week, with 3 consecutive treatments as one course. One week after pregnancy, sows can be fed 50 ml choline chloride solution until 3 days before farrowing, when it is stopped. Three days before farrowing, add 1 g VC per sow per day to the daily ration to prevent the suffocation death phenomenon caused by postpartum hemorrhage in sows.
????Strengthen Sow Management and Pregnancy Protection
Pregnant sows are especially sensitive to sudden environmental changes. Whether exercise, feeding, catching, or overheating, all are adverse stress and stimulation and may cause pregnant sows to miscarry, so a normal routine of life must be established. Pregnant sows should be kept in single pens, managed individually, and fed individually to prevent pigs from biting and fighting each other and causing miscarriage.