Heat Stress in Pigs

How does heat stress impact pigs?

Pigs are more sensitive to hot weather than other livestock animals and can easily be negatively impacted by heat. Heat stress can begin in sows, boars and finishing pigs in temperatures as low as 70°F. Pigs do not have functional sweat glands and, therefore, do not have a way of efficiently cooling themselves. Pigs also have relatively small lungs for their body size, making it difficult for them to remove excess internal heat through respiration.

Heat stress can take a serious toll on pig performance, especially in breeding herds and finishing pigs. Wide fluctuations in temperature are often immensely stressful, resulting in reduced performance, health problems and economic loss. Pigs exhibit heat stress in many ways, and the impact can be seen in both the short and long term.

Preventing heat stress in pigs

• Control the temperature. This is especially important during early and late summer, as wide variations between temperatures in the day and the night can compound the stress that the animals are experiencing. Avoid temperature shifts of more than a few degrees. Monitoring controllers and using sensors and temperature probes is essential to ensure that all systems are operating as expected, especially during periods of high heat.
• Increase ventilation and ensure adequate space. Since pigs can generate an enormous amount of heat, focus on practices that produce less heat. Ensure that each pig has enough space and ventilation. Keep pigs’ movements minimal, and do not disturb the animals during peak temperatures. Check all fans, inlets and soffits to ensure that they are clean and running properly. Worn-out fans, bearings or wiring can have dramatic consequences.
• Use sprinklers, cool cells and fans. Even if you have cooling equipment, ensure that it is set up correctly and is functioning properly.
• Feed during cooler hours. Time feedings to coincide with the cooler parts of the day, such as early mornings and later evenings.
• Focus on water quality and access. It is very important to make sure that pigs have unlimited access to fresh and cool drinking water, as drinking levels can also have a major effect on feed intake. Evaluating pressure and taking water samples at the beginning and end of the water lines can help confirm that the water is of the best quality possible.
• Monitor your pigs. Even if you think it might not feel overly warm, pigs can still be affected by the additional heat they create. Watch for signs that your pigs are overheating, such as faster breathing, fluctuations in feed and water intake levels, reduced activity and lying stretched on the floor (often separated from others).
• Move and transport work pigs early. Keep them in groups and let them set the pace. Spend time with them prior to the move to ease their stress. Keep movements minimal, and do not disturb the animals during the times of day when peak temperatures occur.
• Tailor diets to include technologies that will support them during stressful periods. Data has shown that offering pigs a combination product that includes organic acids, electrolytes, enzymes and probiotics can support young animals during times of stress. Organic acids support probiotic growth in the gut, and enzymes can help to enhance intake and digestibility.