Summer Heat Management in Grow/Finish Barns

By Dan Cudmore*, Western Region Swine Specialist
*Adapted from Brumm (; June 26, 2012)

It’s hot and miserable in most hog barns, so here are some management tips for summer heat.

Most customers don’t completely understand the impact of heat on grow/finish pigs. Last year, the week of July 18th showed a reduction in sale weights of nearly three pounds MORE than normal during that same time frame over the previous five years.

The common belief is that because pigs are leaner with less backfat, they have less insulation therefore allowing more heat to escape from their bodies. This is not true. In fact, exactly the opposite is true. Because today’s pigs have a higher rate of lean gain, these pigs do not deal with hot weather as well as previous genetics did. There is evidence that today’s pigs generate 10-15% more heat, and evidence shows that this is because the pig has less tolerance to heat.

This means that today’s pig gets hot at a lower temperature and therefore adapts certain body mechanisms to deal with being hot at a lower temperature. Data from the Netherlands suggests that a 130-lb pig on partial slats began to reduce feed intake at 78°F. We have all been taught not to sprinkle pigs until temperatures reach 85-90°F. Some tunnel-vent barn operators believe that they don’t need to sprinkle pigs at all due to the high rate of air movement over the pigs. Think about heat exchange prinsciples. When you blow 95°F air over pig skin that is 95°F not much cooling can occur without some type of evaporation! Since a pig cannot sweat, it is up to us to add the water for evaporation.

Available data has shown that big droplets are better than a mist for cooling animals. Fine mist tends to drift more into feeders and onto curtains, causing feeders to plug and mold to grow on curtains. A heavy droplet wets pigs more thoroughly and quicker than mist.

It’s recommended to use a nozzle size that will wet 60% of the pigs in the pen in under two minutes and then turn the sprinkler off for 15-20 minutes to allow drying.
Begin sprinkling grow-finish by setting the sprinklers to come on at 20°F over the set point on your controller.