The Effects of Different Temperatures on Pigs and Countermeasures

I. Effects of ambient temperature on pigs

1. Effects on pig health. In a continuously high-temperature environment, the resistance of pigs is significantly reduced, the body heat balance is disrupted, body temperature rises, coma occurs, heat stroke develops, and in severe cases death results. In a low-temperature environment, in order to conserve heat, pigs constrict their peripheral blood vessels, causing local frostbite. Low temperatures cause respiratory diseases and also often lead to rheumatism, arthritis and other diseases. Low temperatures have a greater impact on piglets; according to statistics, half of the dead piglets were frozen to death or died from cold-related diseases. To keep warm, newborn piglets constrict their peripheral blood vessels, causing local frostbite. In a low-temperature environment, the incidence of diseases such as diarrhea in newborn piglets increases significantly.

2. Effects on pig feed intake. In a high-temperature environment, pigs reduce their feed intake in order to reduce internal heat production. When the ambient temperature is lower, heat loss from the pig's body increases, and to maintain body heat balance, the pig's feed intake increases.

3. Effects on pig feed digestibility. Ambient temperature affects the retention time of feed in the digestive tract. In a high-temperature environment, feed remains in the digestive tract for a longer time, so feed digestibility is higher; in a low-temperature environment, gastrointestinal motility speeds up, food remains in the digestive tract for a shorter time, and digestibility is lower.

4. Effects on pig growth, weight gain and feed conversion rate. In high- and low-temperature environments, the maintenance requirements of pigs increase, mainly for maintaining body heat balance (heat dissipation and cold resistance), the feed conversion rate decreases, and growth speed and weight gain also decrease. Severe cold and heat stress stop pig growth and weight gain, all the feed consumed is used for maintenance requirements, and weight loss may even occur.

5. Effects on pig reproduction. When the ambient temperature is above 33°C-35°C and the body temperature of the boar exceeds 40°C, the testicular temperature rises, semen quality declines accordingly, the sperm count decreases, sperm motility declines, the proportion of abnormal sperm increases, and heat stress reduces the boar's libido.

In hot seasons, sows often show anestrus and behavioral anestrus (ovulation without estrous symptoms), and the estrous cycle is also prolonged. Sows are particularly sensitive to high temperatures during the 1-3 weeks before and after mating; if the ambient temperature is too high at this time, the conception rate is significantly reduced, and early embryonic absorption and death occur. High temperatures affect normal fetal development and, together with reduced sow feed intake and increased maintenance energy, cause fetal malnutrition and stunted development, resulting in low piglet birth weight and slow growth after birth. High temperatures reduce the immunoglobulin content in sow milk, lowering piglet resistance and resulting in a low survival rate.

II. Measures to take under high-temperature conditions

1. Increase the level of the diet (especially energy, protein and vitamins) and provide fresh, sufficient and clean drinking water.

2. Strengthen ventilation and reduce stocking density. Remove manure promptly and keep the pig house clean. Use shade measures to reduce sunlight exposure. Spray, splash and bathe to promote evaporative heat loss from the pig's body.

3. Feed in the cool morning and evening, or feed wet mixed feed.

4. Add anti-stress drugs to the feed or drinking water, such as vitamin C, Subu 14, etc.

III. Measures to take under low-temperature conditions

1. Ensure the nutritional level of feeding, especially high energy, and add fat if necessary. If conditions permit, warm water can be given to pigs to drink.

2. Reasonably increase stocking density and use bedding straw or wooden boards. Reduce humidity inside the house and remove manure and urine promptly.

3. Increase the number of feedings and the feeding amount.

4. Do a good job of keeping the pig house warm. Prevent drafts from invading, ventilate appropriately (preferably at noon when the temperature is higher), and remove harmful gases and water vapor inside the house. Take heating measures when necessary; for outdoor rearing, cover with a plastic greenhouse to help keep warm.