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Pregnant Sows Experiencing Heat Stress are Negatively Impacting Piglets Overall Health

Pregnant Sows Experiencing Heat Stress are Negatively Impacting Piglets Overall Health

By: Kendra Waldenberger, UMN Extension Ag Intern


The summer heat and humidity can feel unbearable, especially for pigs who have an inability to sweat. Heat-stressed pigs experience decreased feed efficiency and growth rate, causing a significant economic loss for swine producers. In addition, when pregnant sows are heat-stressed their unborn piglets have negative immune responses when exposed to pathogens. Recognizing the signs of heat stress and implementing heat management practices can reduce potential revenue loss during the summer months and ensure a healthy and profitable future generation of pigs. 


The Agricultural Research Service tested two groups of 16 piglets. The first group of piglets was born to sows housed in a comfortable temperature of 64°F, and the second group of sows was exposed to heat stress conditions of 79 - 97°F during the first half of their pregnancy. An imitated pathogen attack was performed on both groups of piglets and blood samples were collected to monitor their immune response. The utero heat-stressed piglets had increased levels of the stress hormone cortisol, and cytokine, an indicator of a hypersensitive immune response. The results are concerning because in a real production setting hypersensitive immune systems could lead to increased chances of infection, pain, organ failure, and more. 


Knowing and recognizing signs of heat stress in pigs will help the farmer know when they are experiencing discomfort. When pigs are feeling the heat they will pant, have decreased activity, eat less feed, lay down stretched out away from other pigs, and consume an excessive amount of water. 


Implementing effective heat management strategies will mitigate the chances of developing piglets with hypersensitive immune systems. Maintaining a consistent temperature in the barn that only fluctuates a few degrees is key to relieving stress on pigs. During the summer months, it’s important that pigs have enough space with proper ventilation to help keep cool. When moving or transporting pigs, opt for earlier in the morning and let the pigs set the pace to avoid overexertion. 


Feed and water play a critical role in heat stress management. Providing 24-hour access to clean and cool water is a must during warm temperatures. Shifting feeding times to earlier in the morning or later during the night will also provide relief to pigs as body temperature rises when digesting feed. Consult a nutritionist about altering rations to better support pigs’ nutritional needs during the summer to lessen the impact of heat stress. 


Managing heat stress during the summer can be challenging, but it's in the best interest of the pigs and future litters to do so. Identifying pigs that are showing symptoms and treating them right away will help keep them healthy and profitable. 



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