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What to do if your poultry suffers from heat stress

What to do if your poultry suffers from heat stress


It's summer again and the higher temperatures can cause heat stress for your poultry. These changes in temperature therefore require adjustments in the management of your chickens. The heat causes a reduction in productivity, an increase in mortality and a loss of quality. But how can you prevent this?

In principle, chickens can handle heat reasonably well, but not with sudden increases in temperature or humidity. They then quickly suffer from heat stress, which in turn has consequences for their health. To prevent these consequences as much as possible, it is important to take measures in time. According to poultry veterinarian Peter Wijnen, the implementation of these measures is not only the responsibility of a poultry farmer. This responsibility also lies with the suppliers and customers.

Peter Wijnen has a large practice that is mainly active in the Netherlands and Germany. He also regularly provides consultations in Southern Europe, the Middle East and Russia. This gives him a good picture of the production process in countries with varying weather conditions and he knows what influence the climate has on the health of poultry.


Chickens cannot sweat

Chickens can get used to higher temperatures fairly quickly, but they have difficulty with rapid temperature changes. This can cause a lot of stress, especially in combination with a high relative humidity. For example, in the event of a too high occupancy, a startle reaction, loading and unloading, but also when the truck stands still for too long in the full sun during transport.

Chickens do not have sweat glands. They must get rid of most of their body heat through breathing. This is more difficult for them when the air is warm and humid. This causes them to breathe faster and more shallowly. This way they lose a lot of CO2 and the acidity of the blood decreases. Due to the heat, the chickens eat less feed and use a lot of energy to get rid of the excess heat. As a result, laying hens will produce eggs with thinner shells and broilers grow less quickly. They do drink more at higher temperatures, but they also excrete more minerals as a result. Something that can quickly result in intestinal disorders and more mortality. According to veterinarian Wijnen, the consequences of this are often underestimated and measures must therefore be taken in time.


The humidity must be well-balanced with the ambient temperature.



Adjust the ventilation

Van Wijnen advises reducing the occupancy rate before the start of a heat period. Fewer animals per square meter ensures better air movement between the animals and less heating. In addition, there are a number of other matters that require some extra attention:

  • Ensure sufficient ventilation capacity and an adjustment of the P-band to enable faster switching from low to high.
  • Make sure that air inlets, fans and ducts are clean and function properly.
  • Prune away vegetation that could pose a problem for proper ventilation.
  • Make sure that auxiliary fans are available for extra air extraction and circulation.
  • Check the operation of the cooling installation.
  • Make sure all nozzles are clean and functioning.


According to Wijnen, the humidity is very important for good animal health. A good balance between temperature and humidity is needed. High humidity is always bad, because the chickens cannot lose their heat. A temporary increase is not so bad, if the temperature is not too high and the litter does not get too wet. Even when the temperature is very high during the day, it is not a problem if the litter becomes a bit wetter due to high humidity (as a result of extra cooling). This will dry up at night.

When a thunderstorm approaches, high humidity can cause problems. The temperature is usually already high by then and the rapid change in the house climate can cause considerable stress for the chickens. It can cool down quite quickly after a thunderstorm. That is why it is important that you try to prevent the ventilation system from drawing this cold into the house too quickly.


Give your chickens plenty of time to drink fresh, clean water


Sufficient fresh and clean water

Chickens use water to get rid of heat through respiration. As a result, they also drink more water at higher temperatures. Therefore, give them more time in hot weather (and unlimited in heat) to drink fresh and clean water. Broilers, for example, show a significant increase in water consumption at a temperature of 30 – 35 °C. This can even be 2 to 3 times as much during a period of heat stress. For every degree that the ambient temperature rises, water consumption increases by approximately 7%. Make sure the water is not too cold. This can cause intestinal problems and diarrhea. Fresh drinking water has a temperature of 7 – 8 °C lower than the ambient temperature.

Chickens always pant at high temperatures, even if there is sufficient drinking water available. So this is not necessarily a cause for panic. But as soon as a chicken puts its head between its feathers, that's a bad thing, because then it's often too late. Wijnen therefore advises to keep the animals moving at high temperatures.

He also advises adding electrolytes and extra vitamins C and E to the drinking water a day before it gets really hot. Keep in mind that vitamin C only stays good for 6 hours in a water solution and must therefore be refreshed every 6 hours. Electrolytes are important for normal cell function and growth.

These additives not only supplement possible deficiencies in the blood during a period of heat stress, but also stimulate water intake. By administering electrolytes and a higher water consumption, mortality due to heat stress can be significantly reduced. (The combination of administering vitamins and minerals with bicarbonate is the very best, in this way the pH value of the blood is better guaranteed.)

Give your chickens less feed on very hot days, or feed with a lower energy value.


Feed and water

The advice of veterinarian Wijnen is to give chickens less feed on very hot days, or feed with a lower energy value. Preferably early in the morning, because then it is still cool.

The availability of feed has a major influence on water intake. Research has shown that feed and water intake in broilers are closely linked. If they do not have access to food, they will drink little water, even if water is available in abundance. Conversely, they will also eat little or no food if water is not available.

In broiler breeders, the absence of feed often causes them to peck more at the nipple drinker. This leads to higher water consumption and more spillage.

Due to their lower weight, laying hens are in principle less sensitive to heat, but it does have consequences for the quality of the eggshell. That is why Wijnen advises ensuring that the hens get extra calcium at high temperatures. For example, by means of grit.


Water quality

Research has also shown that the water consumption of broilers is influenced by water quality and feed composition. Poor quality water can lead to disease and leaky nipple drinkers. This results in wet litter and an increased production of ammonia. All this can in turn lead to reduced welfare of the animals.


Broilers have a wide pH tolerance, but a pH lower than 4 or higher than 8 can reduce water intake. The presence of iron, manganese and nitrates in drinking water has little effect on broiler production. However, it does increase the chance of biofilm formation in the system. In addition, the presence of these substances can result in extra wear, blockages and leaks. Moreover, a biofilm can cause reduced production, health problems, the breakdown of additives, a reduced effect of medication/grafts and even contribute to the development of resistance.

Controls of drinking water samples that are carried out to test the suitability of the water for poultry show that poultry farmers generally pay little attention to drinking water management. Over the past 3 years, an average of 34% of the drinking water samples turned out to be unsuitable for poultry.

This often explains the health problems in poultry flocks. Careful cleaning and regular checking of the drinking water quality can significantly improve performance. It goes without saying that drinking water must not have a negative effect on the growth and health of the animals. In addition, harmful bacteria can end up in the egg or meat, which can eventually cause serious problems.


Peter Wijnen | Poultry vet

Poultry practice 'De Achterhoek', Ruurlo

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