Heat stress in pigs is dangerous and can have serious consequences for the health, growth, and reproduction of the animals. Once ambient temperatures rise to around 25 degrees Celsius, pigs begin showing signs of heat stress, and at higher temperatures the risk of serious harm increases rapidly. In this article, we answer the most frequently asked questions about heat stress in pigs: from the first symptoms to concrete measures you can take to protect your animals.
At what temperature do pigs start suffering from heat?
Pigs begin to suffer from heat when ambient temperatures rise above 25 degrees Celsius. The thermoneutral zone for adult pigs lies between 15 and 25 degrees Celsius. Above that threshold, animals must expend additional energy to regulate their body temperature, which comes at the expense of growth, reproduction, and overall health.
Piglets and sows are more sensitive than finishing pigs. For newborn piglets, the ideal temperature is considerably higher — around 30 to 34 degrees Celsius — while sows can already come under pressure at temperatures above 22 degrees Celsius. The combination of temperature and humidity also plays a major role: at high relative humidity, pigs experience the heat more intensely because sweat evaporates less efficiently.
Pigs do not have active sweat glands across their entire body, which means they can only dissipate heat through respiration and by making contact with cool surfaces. This makes them particularly vulnerable to high temperatures as a species, especially compared to other farm animals.
What are the symptoms of heat stress in pigs?
The symptoms of heat stress in pigs are easy to recognize and appear relatively quickly once the temperature exceeds the comfort zone. The most common signs are rapid and shallow breathing, reduced activity, lower feed intake, and seeking out cool spots or contact with wet floors.
More specific symptoms you may observe in the barn:
- Panting and open-mouth breathing
- Elevated body temperature (normal is 38.5 to 39.5 degrees Celsius)
- Increased water intake
- Reddening of the skin, particularly on the ears and belly
- Lethargy and reduced movement
- Pigs avoiding lying on top of each other and spreading out across the barn
- In sows: reduced estrus and decreased appetite
In severe cases, heat stress can lead to loss of consciousness or death. It is important to take early warning signs seriously, as the transition from mild to severe heat stress can happen quickly, especially in young animals or animals in poor condition.
What damage does heat stress cause in pigs?
Heat stress causes both physiological and economic damage in pigs. At the cellular level, heat leads to oxidative stress, damage to the intestinal wall, and disruption of hormonal balance. This translates into poorer technical performance, reproductive disorders, and an increased risk of infection and mortality.
The damage is most pronounced in the following areas:
- Intestinal integrity: Heat stress damages the tight junctions in the intestinal wall, increasing its permeability. Harmful bacteria and toxins can then more easily enter the bloodstream, leading to inflammation and greater susceptibility to infection.
- Reproduction: In sows, heat stress results in fewer live-born piglets, lower birth weights, and reduced milk production. Summer breeding is a particularly critical period, as egg cell quality and placental development are directly affected by ambient temperature.
- Carcass quality: Finishing pigs exposed to heat show greater fat deposition and reduced muscle growth. This has a direct negative impact on carcass composition and the economic return per animal.
- Immune function: Chronic heat stress suppresses the immune system, making animals more susceptible to respiratory and gastrointestinal conditions.
- Metabolic load: The body uses extra energy to regulate body temperature — energy that would otherwise be directed toward growth or milk production.
How does heat stress affect feed intake and growth?
Heat stress significantly reduces feed intake in pigs, sometimes by as much as 20 to 40 percent during prolonged periods of heat. Pigs eat less because digesting feed generates heat, and the body tries to avoid this additional heat load. This directly leads to lower daily weight gain and a worse feed conversion ratio.
The effects on growth are not limited to the period of heat stress itself. Even after the environment cools down, it can take several days before feed intake and growth potential are fully restored. Finishing pigs lose valuable growth days as a result, which extends the time to slaughter weight and increases production costs.
For lactating sows, the situation is especially critical. Reduced feed intake during the nursing period leads to greater body condition loss, which in turn negatively affects fertility in the next gestation. Piglets nursed by a heat-stressed sow reach lower weaning weights, which has an adverse effect on their subsequent growth and resilience.
How can betaine help with heat stress in pigs?
Betaine is a natural osmolyte that helps cells maintain their water balance under stress conditions such as heat. By stabilizing osmotic pressure within the cell, betaine protects cell structures against dehydration and stress. This translates into better heat tolerance, preserved intestinal integrity, and more stable technical performance during warm periods.
Scientific research shows that betaine activates several protective mechanisms in pigs during heat stress:
- Osmoregulation: Betaine acts as an osmoprotectant and reduces cellular shrinkage and stress in the intestinal wall, keeping tight junction proteins such as occludin and claudin-1 intact.
- Methyl donor function: As a methyl donor, betaine supports essential metabolic processes, even when feed and nutrient intake temporarily declines due to heat.
- Reproductive support: Scientific research shows that betaine supplementation in pregnant sows increases the number of live-born piglets — an effect that is particularly relevant during summer breeding when heat stress threatens placental development.
- Gut health: Betaine reduces oxidative stress and protects the intestinal wall during infection or heat stress, lowering the risk of spreading infections.
- Carcass quality: In finishing pigs, betaine helps maintain lean meat growth and limit fat deposition, even under suboptimal conditions.
For more information about how betaine works as an active ingredient, visit our page on betaine in animal nutrition.
What measures reduce heat stress in pig barns?
Reducing heat stress in pigs requires a combination of structural, management, and nutritional measures. No single measure is sufficient on its own; a layered approach delivers the best results and protects animals even during prolonged heat periods.
Barn climate and ventilation
Good ventilation is the first line of defense. Ensure adequate airflow and consider using fans or misting systems to cool the barn. Whitewashing the roof reduces heat absorption, and shading during the hottest hours of the day can significantly lower radiant heat load. Cool drinking water encourages water intake and helps regulate body temperature.
Feeding and drinking water strategy
Adjust the feeding program during hot weather: feed preferably in the early morning and late evening, when temperatures are lower. Increase the nutrient density of the ration to partially compensate for reduced feed intake. Always ensure fresh, cool drinking water is available, as water intake increases significantly in the heat. Adding betaine and supportive additives via the drinking water is a practical and flexible way to provide animals with extra support during warm periods. Browse our range of drinking water and feed additives for more options.
How Jodoco helps with heat stress in pigs
At Jodoco, we have more than 25 years of experience developing scientifically supported solutions for animal nutrition, with betaine as the central active ingredient. For pig farmers who want to tackle heat stress in a structural way, we offer targeted products that address the physiological challenges that heat presents.
Our approach combines multiple mechanisms of action in a single formula, so you do not have to choose between osmoregulation, gut health, or reproductive support. Specifically, we offer:
- Jodobet: Natural betaine as an osmolyte and methyl donor, proven effective in improving heat tolerance, intestinal integrity, and carcass quality in finishing pigs and sows.
- Grovax: A combination of organic acids, slow-release butyrate, MCFAs, and essential oils that strengthens gut health and fits within an antibiotic-free strategy, including during periods of stress.
- Drinking water additives: Flexibly administered via the drinking water system, allowing you to tailor the dosage precisely to conditions in the barn, even during acute heat waves.
Want to find out which solution best fits your operation? Contact us and we will be happy to help you develop an effective approach to heat stress in pigs.
