Heat stress in pigs is dangerous and can have serious consequences for the animals’ health, growth, and reproduction. Pigs begin to show signs of heat stress at ambient temperatures of around 25 degrees Celsius, and the risk of serious harm increases rapidly at higher temperatures. In this article, we answer the most frequently asked questions about heat stress in pigs: from the first symptoms to specific measures you can take to protect your animals.
At what temperature do pigs start to suffer from the heat?
Pigs begin to suffer from heat stress when the ambient temperature rises above 25 degrees Celsius. The thermoneutral zone for adult pigs ranges from 15 to 25 degrees Celsius. Above that threshold, the animals must expend extra 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 become stressed even at temperatures above 22 degrees Celsius. The combination of temperature and humidity also plays a major role: when relative humidity is high, pigs perceive the heat as more intense because sweat evaporates less efficiently.
Pigs do not have active sweat glands throughout their bodies, which means they can only dissipate heat through breathing and by coming into contact with cool surfaces. This makes them particularly vulnerable to high temperatures, especially compared to other farm animals.
What are the symptoms of heat stress in pigs?
The symptoms of heat stress in pigs are easily recognizable and appear relatively quickly once the temperature exceeds the comfort zone. The most common signs are rapid and shallow breathing, reduced activity, decreased feed intake, and seeking out cool spots or contact with wet floors.
More specific symptoms you may notice in the barn:
- Panting and open-mouth breathing
- Elevated body temperature (normal range is 38.5 to 39.5 degrees Celsius)
- Increased water absorption
- Reddening of the skin, particularly on the ears and abdomen
- Lethargy and reduced mobility
- Pigs that avoid lying on top of each other and spread out across the pen
- In sows: reduced heat and decreased appetite
In severe cases, heat stress can lead to unconsciousness or death. It is important to take early signs seriously, as the progression from mild to severe heat stress can happen quickly, especially in young animals or those in poor physical condition.
What kind of 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 results in poorer technical performance, reproductive disorders, and an increased risk of infections 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. This makes it easier for harmful bacteria and toxins to enter the bloodstream, leading to inflammation and an increased susceptibility to infections.
- Reproduction: In sows, heat stress leads to fewer live-born piglets, lower birth weights, and reduced milk production. Summer breeding is a particularly critical time, as the quality of the egg and placental development are directly influenced by the ambient temperature.
- Carcass Quality: Fattening pigs exposed to heat exhibit increased fat deposition and reduced muscle growth. This has a direct negative effect on carcass composition and the economic yield per animal.
- Immune Function: Chronic heat stress suppresses the immune system, making animals more susceptible to respiratory and gastrointestinal disorders.
- Metabolic load: The body expends extra energy to regulate its body temperature—energy that would otherwise be used for growth or milk production.
How does heat stress affect feed intake and growth?
Heat stress significantly reduces feed intake in pigs, sometimes by 20 to 40 percent during prolonged heat. Pigs eat less because the digestion of feed generates heat, and the body tries to avoid this additional heat. This directly leads to lower daily growth and a poorer feed conversion ratio.
The effects on growth are not limited to the period of heat stress itself. Even after the environment has cooled down, it takes several days for feed intake and growth potential to fully recover. As a result, finishing pigs miss out on valuable growth days, which extends the time to market and increases production costs.
The situation is particularly critical for lactating sows. Reduced feed intake during the lactation period leads to greater loss of body condition, which in turn negatively affects fertility in the next pregnancy. Piglets nursed by a sow experiencing heat stress achieve lower weaning weights, which adversely affects their subsequent growth and immunity.
How can betaine help alleviate heat stress in pigs?
Betaine is a natural osmolyt that helps cells maintain their water balance under stressful conditions such as heat. By stabilizing the osmotic pressure within the cell, betaine protects cellular structures from dehydration and stress. This results in improved heat tolerance, maintenance of intestinal integrity, and more stable performance during hot 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, which helps keep 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 decrease 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, which lowers the risk of severe infections.
- Carcass quality: In finishing pigs, betaine helps maintain lean meat growth and limit fat deposition, even under suboptimal conditions.
For more information on how betaine works as an active ingredient, visit our page on betaine in animal feed.
What measures can be taken to reduce heat stress in the pig barn?
Reducing heat stress in pigs requires a combination of architectural, management, and nutritional measures. No single measure is sufficient on its own; a multi-layered approach yields the best results and protects the animals even during prolonged heat waves.
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 stress. A cool drinking water temperature encourages water intake and helps regulate body temperature.
Food and Drinking Water Strategy
Adjust the feeding schedule 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 lower feed intake. Ensure that fresh, cool drinking water is always available, as water intake increases significantly in hot weather. Adding betaine and supportive additives to the drinking water is a practical and flexible way to provide extra support to the animals during hot periods. Check out our selection of drinking water and feed additives.
How Jodoco Helps with Heat Stress in Pigs
At Jodoco, we have more than 25 years of experience in developing scientifically based solutions for animal nutrition, with betaine as the key active ingredient. For pig farmers who want to address heat stress systematically, we offer targeted products that address the physiological challenges posed by heat.
Our approach combines multiple mechanisms of action into a single formula, so you don’t have to choose between osmoregulation, gut health, or reproductive support. Specifically, we offer:
- Jodobet: Natural betaine as an osmolyt 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 supports gut health and fits into an antibiotic-free strategy, even during periods of stress.
- Drinking water additives: Can be flexibly administered through the drinking water system, allowing you to fully adjust the dosage to the conditions in the barn, even during severe heat waves.
Would you like to know which solution best suits your business situation? Contact us, and we’d be happy to work with you to develop an effective approach to heat stress in pigs.
