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University of Minnesota Extension

Heat stress in swine affects production

Quick facts

Pork producers shouldn’t overlook the effects of heat stress. Heat stress causes

  • Lower feed intake in grow-finish pigs during the summer.
  • Harmful effects in the sow herd during breeding, gestation and lactation.
  • Lasting harmful effects in offspring of sows that had heat stress during pregnancy.

It’s important to prevent heat stress to limit these harmful effects.

sows laying down.
Heat stress during gestation can have a detrimental effect on litter size and health.

Heat stress affects both grow-finish and breeding pigs

Pigs are more sensitive to heat than other animals because they can’t sweat. Thus, high temperatures can lead to heat stress, which causes poor performance. Often, pork producers only think about grow-finish pigs when they consider the harmful effects of heat stress. In reality, heat stress also affects the breeding herd.

Dr. Steve Pollmann, Vice President of Smithfield’s Hog Production Division (formerly Murphy-Brown LLC.) estimated heat stress costs the American swine industry $900 million each year. Of that, about $450 million of loss is in the grow-finish stage and about $450 million of loss is in the breeding herd.

Ideal temperatures for housed pigs 

As a pig gets older and heavier, its ideal temperature declines, see the table below. Thus, heat stress is a greater concern in older finishing pigs (greater than 110 pounds), sows and boars than in younger pigs. Heat stress begins to affect sows, boars and finishing pigs at about 70 degrees F. If temperatures remain above 80 degrees F for more than two to four days, decreases in performance and reproductive efficiency can result if cooling relief isn’t available.


Sarah Schieck, Extension educator

Reviewed in 2019

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