{"id":10811,"date":"2026-05-20T06:00:00","date_gmt":"2026-05-20T06:00:00","guid":{"rendered":"https:\/\/jodoco.com\/?p=10811"},"modified":"2026-05-20T11:41:04","modified_gmt":"2026-05-20T11:41:04","slug":"how-does-heat-stress-affect-the-immune-system-of-livestock","status":"publish","type":"post","link":"https:\/\/jodoco.com\/en\/how-does-heat-stress-affect-the-immune-system-of-livestock\/","title":{"rendered":"How does heat stress affect the immune system of livestock?"},"content":{"rendered":"

Heat stress significantly weakens the immune system of livestock. When animals are exposed to high temperatures for too long, the body shifts its energy priority from defense to temperature regulation. This makes animals more susceptible to infection, delays recovery and increases the risk of production loss. In this article, we answer the most frequently asked questions about heat stress and its immune effects on farm animals. <\/p>\n

What happens in the body of cattle during heat stress?<\/h2>\n

During heat stress, an animal’s body tries to lower its core temperature by sending more blood to the skin, increasing respiration and slowing down digestion. This takes an enormous amount of energy and disrupts virtually all physiological processes simultaneously. The intestinal barrier weakens, cell hydration drops and oxidative stress increases. <\/p>\n

One of the first consequences is reduced feed intake. Animals eat less because digestion produces heat, which exacerbates heat stress. At the same time, water intake increases, but that compensation is not nearly enough to restore osmotic balance. Cells become dehydrated, further hindering cell metabolism. <\/p>\n

At the cellular level, the production of free radicals increases. This oxidative stress damages tissues, including the intestinal epithelium. The tight junctions, the protein connections that link intestinal cells together, become less firm. This increases intestinal permeability, making it easier for harmful bacteria and toxins to penetrate the intestinal wall. This phenomenon is also known as “leaky gut” and is a direct threat to the animal’s overall health. <\/p>\n

How does heat weaken the immune response of farm animals?<\/h2>\n

Heat stress suppresses the immune response of farm animals on multiple levels simultaneously. The body reduces the production of immune cells, decreases the activity of anti-inflammatory mechanisms and reduces antibody production. At the same time, cortisol production increases as a stress response, further inhibiting the immune system. <\/p>\n

Cortisol is a stress hormone that is useful in acute situations but remains chronically elevated with prolonged exposure to heat. This hormone inhibits the action of lymphocytes and macrophages, two key elements of the immune response. As a result, animals respond more slowly to pathogens and vaccinations are less effective during hot periods. <\/p>\n

In addition, heat stress disrupts one-carbon metabolism, the biochemical process by which methyl groups are transferred for the production of DNA, proteins and immune molecules, among other things. A lack of methyl donors such as betaine<\/a> exacerbates this problem. Without enough methyl donors, cell renewal is slower and the immune system functions less efficiently. <\/p>\n

Which animal species are most vulnerable to heat stress?<\/h2>\n

Poultry, pigs and high-yielding dairy cows are the most vulnerable to heat stress in farm animals. These animal species combine high metabolic intensity with limited ability to dissipate heat, making them particularly sensitive to temperature increases. <\/p>\n

Poultry<\/h3>\n

Broilers and layers have no sweat glands and rely entirely on panting to dissipate heat. Fast-growing breeds such as the Ross 308 also produce a lot of metabolic heat due to their high growth rate. Under heat stress, feed intake drops sharply, egg production declines and shell strength deteriorates. Research shows that betaine in poultry supports breast muscle weight via improved cellular hydration and antioxidant protection in heat. <\/p>\n

Pigs<\/h3>\n

Pigs hardly sweat and are therefore very sensitive to high ambient temperatures. Sows in late gestation or early lactation are especially vulnerable: heat stress reduces feed intake, worsens milk production and can negatively affect piglet birth weight. In finishing pigs, heat stress leads to reduced lean meat growth and higher fat deposition, with direct consequences for carcass quality. <\/p>\n

Dairy<\/h3>\n

Highly productive dairy cows generate enormous amounts of metabolic heat due to their intensive metabolism. Even at relatively mild temperatures, they can go into heat stress. The consequences are noticeable in milk production, fertility and resistance. In ruminants, betaine supports osmotic balance and microbial protein synthesis in the rumen, which helps maintain production during hot periods. <\/p>\n

What diseases and infections occur more frequently with heat stress?<\/h2>\n

Heat stress significantly increases the risk of intestinal infections, respiratory diseases and secondary bacterial infections. The combination of a weakened immune system, compromised gut barrier and increased oxidative stress makes animals more susceptible to a wide range of pathogens. <\/p>\n

In poultry, heat stress increases susceptibility to coccidiosis, a parasitic intestinal infection normally well controlled by an intact immune system. When intestinal integrity drops, coccidia can penetrate and cause damage more easily. Gram-negative bacteria such as Salmonella and E. coli also benefit from the weakened intestinal barrier. <\/p>\n

In pigs, we see more frequent respiratory problems during warm periods, partly because animals breathe faster and therefore inhale more pathogens. Diarrhea in weaned piglets increases as the osmotic balance in the gut is disturbed. In dairy cattle, the risk of mastitis and fertility problems increases, in part because of elevated cortisol levels that suppress the immune response. <\/p>\n

How can livestock producers support the immune system during heat?<\/h2>\n

Livestock producers can support their animals’ immune systems during heat stress by optimizing water intake, restoring osmotic balance, reducing oxidative stress and protecting gut integrity. A targeted feeding and drinking water strategy is most effective here. <\/p>\n

Practical measures that directly contribute to improved heat tolerance:<\/p>\n