Managing heat stress for healthy pigs year-round

Rising global temperatures and increasingly unpredictable weather patterns mean that heat stress is no longer a seasonal issue. For pig producers, managing heat stress is essential for maintaining the performance, welfare and profitability of their herds — not just in the height of summer, but year-round.

What is the problem?

Producers commonly face heat stress issues within their pig production systems, as pigs are particularly susceptible to heat stress due to their limited ability to regulate body temperature. These issues are often seasonal, but they can be challenging year-round in some countries.

Pigs are exposed to heat stress when the ambient temperature of their environment exceeds the upper critical temperature of their thermo-neutral zone — or, more simply put, when the pig can no longer balance its body heat production with its body heat losses (Figure 1).  

Beyond the temperature of rooms, factors such as relative humidity, ventilation, stocking density, and housing design all play roles in determining whether pigs’ body heat can be balanced.

Figure 1. Interaction of temperature and humidity in determining heat stress potential in pigs (left), and how pigs try to keep cool (right).

What is the outcome?

Heat stress can be categorized as either acute (a short and rapid temperature increase) or chronic (high temperatures persisting for extended periods). The exposure of pigs to heat stress results in heightened energy requirements and an increase in free-radical production, leading to oxidative stress. When heat stress persists, these cellular effects result in tissue damage and malfunction.

The production effects of heat stress in pigs are wide-ranging and costly. In sows, we see lower farrowing rates, reduced milk production and compromised litter performance. Growing pigs exposed to heat stress will exhibit reduced feed intake and lower average daily gain.

In addition to the related performance losses, heat stress is also a welfare concern. Signs of heat stress in pigs may include signs of distress, such as increased respiratory rate and lethargy. If left unchecked, heat stress can lead to further discomfort and even to higher mortality rates, especially in finishing pigs.

What can be done?

Farm management plays a critical role in mitigating the environmental conditions that result in heat stress. Ensuring adequate ventilation, reducing stocking density, providing cool drinking water, and adjusting diet specs are all important steps. Recent investigations have shown that nutrition also plays a role in supporting pigs during periods of heat stress — and, specifically, that chelated trace minerals can make a significant impact.

Alltech’s range of chelated trace minerals, including Bioplex® and Sel-Plex® (organic selenium-enriched yeast), can help support pigs’ ability to withstand or recover from heat stress. They do this by addressing the underlying physiological challenges.

Chelated minerals are more bioavailable than inorganic mineral sources, meaning pigs can absorb and utilize them more effectively. This is crucial during heat stress, when feed intakes are reduced and nutrient absorption can be compromised.

Selenium, in particular, plays a central role in the pig’s antioxidant defense system. Recently published research highlights that increasing dietary selenium supply with Sel-Plex for heat-stressed sows can support colostrum and milk composition via improved nutrient profile and higher selenium and antioxidant status and immunoglobulin levels. Furthermore, feeding sows higher dietary levels of selenium in the form of Sel-Plex may support piglet survival rates to weaning.

As climate pressures grow, heat stress is set to become a more persistent and widespread challenge for pig producers. Reducing incidences of heat stress is complex. Therefore, a holistic approach that combines both optimal environmental management and smart nutritional strategies is key. By including in the diet highly bioavailable chelated trace minerals like those found in Bioplex and Sel-Plex, producers can help pigs stay healthy, productive and profitable — no matter the weather.

About the author:

Dr. Hazel Rooney is the European pig specialist within Alltech’s Technology Group, where she leads the development and coordination of technical solutions for pigs across Ireland and Europe. She works closely with customers to enhance pig performance, address industry challenges, and develop tailored programs. In addition to her hands-on approach, she contributes to the industry through technical articles, presentations, and research-driven insights.

Dr. Rooney earned her Ph.D. in swine nutrition from University College Dublin and the Teagasc Pig Development Department in 2019. Her doctoral research focused on maternal feeding strategies during gestation and lactation to optimize annual sow output and to promote the growth and development of progeny from large litters. Before joining Alltech in 2020, she spent a year working as a post-doctoral researcher in the Teagasc Pig Development Department in Ireland.  

I want to learn more about nutrition for pig herd.