Heat stress broiler chickens
To limit the damage from heat stress, various measures can be taken. These are briefly mentioned below:
If it’s hot a chicken gives 60% of its heat via the airways and 40% through contact with its environment. The extra evaporation of fluid from the airways compensates a chicken by drinking more. Therefore provide sufficiënt fresh and cold drinking water of good quality when the temperatures are high. Regularly check the quality of the drinking water at various places in the barn, because the chance of pollution is much higher at high temperatures.
Provide Vitamin C via drinking water at high temperatures. This stimulates the chickens defense system and supports calcium metabolism.
Electrolytes buffer the pH of the blood and maintain the electrolyte balance (sodium / potassium / magnesium balance). This prevents dehydration and damage to the heart muscle.
We can advise you in the best fitting (water) management at high temperatures. In addition, we can test the quality of drinking water for you using the Watercheck. In addition to checking the drinking water installation, the contents in the water, the ratio between the contents and the presence of yeasts and molds are also checked.
Broiler chickens eat less during a long-term heat period. This gives the chickens insufficient protein and energy and the technical performance decreases. A good and possibly adapted composition of the feed can largely eliminate this loss.
Some tips to stimulate feed intake on hot days:
- Do not feed the chickens during the hottest period of the day. Therefore limit the feed intake in the afternoon.
- Provide more concentrated feed where possible.
- To encourage feed intake, you can switch to a pellet sooner.
- Additions to the feed can provide extra support to the chickens
- It is not advisable to add a high percentage of wheat during warm weather. Wheat gives an extra internal heat load of the animal.
Only 25% of the absorbed energy is used to move, to grow, to breathe and to maintain body temperature. The remaining energy is released as heat. In addition to an adaptation in feed, take care of an appropriate management that fits with high temperatures. Ponco can advise you on this
Most failure due to heat stress occurs at the end of a hot day (between 18.00 and 23.00 hours). Therefore, adjust the feed, water and ventilation schedule on hot days to prevent heat stress and increased dropout.
Because of increased breathing, animals emit extra CO2, which changes the pH of the blood. This change is detrimental to the heart muscle and the legwork. Heat stress can also cause mild diarrhea due to increased activity of the gastrointestinal tract. As a result, animals lose the much needed minerals.
Acute heat stress
At a very high temperature and humidity the chickens are at first dazed. The chickens can’t release enough heat via breathing. Heat dissipation through the skin becomes more important. The heart needs to pump harder to send extra blood to the skin. But heat dissipation through the skin is less efficient. The body temperature will increase. The chicken will eventually die due to lack of oxygen and / or heart failure.
Chronic heat stress
At slightly less high temperatures in combination with a high air humidity, the process is slightly different. In an attempt to cool down chickens they are forced to breathe. This can lead to as much as 240 breathing movements per minute. The muscle movements required for this result in extra heat production. With every degree of increase in body temperature, the metabolism accelerates by 20-30%. This means even more heat production. The chickens also loses weight because the heat suppresses the appetite. Due to the high metabolism, extra muscle activity and the use of body reserves, (acidic) waste products are formed, causing the body to acidify and the chickens to die.
At temperatures above 25 degrees Celsius chickens can get problems with their temperature regulation. So start in time with taking measures to make it as easy as possible for your chickens. Heat stress can already occur in chickens from 20 days of age. Adjust the ventilation and the nebulisation / cooling in a timely manner and test them regularly. The holiday period is a suitable moment for this.
Various tips for the ventilation during hot days:
- Use a short band width on the ventilation at a high temperature.
- Ensure a higher air velocity between the chickens. Depending on the height of the inlet valves in the side wall, a high or low vacuum must be set. With a smoke test and a temperature measurement between the chickens you can determine what is desired.
- To create extra air movement, you can switch on the fans of the heater (without it burning).
- Check preventively if sufficient ventilation capacity is present and check that all fans are working.
- Remember that the weight gain in the last days can be very high. Be sure to ensure sufficient ventilation capacity.
- Additional fans can be installed for additional air discharge and circulation.
- Avoid excessive temperature changes between day and night.
- Take care that no cold air is drawn over the chickens in the evening and night. This can especially be the case in houses with length ventilation.
- After a thunderstorm it can suddenly cool down. Prevent the ventilation system from pulling the cold too quickly into the barn.
- Send the incoming air to the animals. This can be done, for example, by tilting the air inlet flaps.
- Provide a continuous under pressure and a sufficiently high air velocity.
- Be sure not to open doors during hot periods. As a result, the under pressure is lost.
- Adjust the P belt to achieve maximum mechanical ventilation more quickly.
- Switch on the cooling system in time, because a stable that is already warm can’t cool down easily. With a good cooling system, you can lower the house temperature by 5 to 7 degrees Celsius.
- In order to optimize the cooling effect of the spray system, the maximum ventilation must sometimes be limited.
- Immediately stop spraying if the temperature does not drop despite the cooling and the humidity rises.
- At a higher RV, the chickens hardly evaporates moisture and can’t cool properly. Decreasing the temperature will further increase the RV. More ventilation to remove damp air is the solution.
- Check the emergency power generator and the alarm function. Make sure the alarm equipment is charged and / or the battery has been replaced.
- Check the function of the sensors in the house. Pay attention also to the place where they are hanging.
- Check the operation of the cooling installation. Check each nozzle.
- Ensure that the air inlets, fans and ducts are clean. If necessary, prune the plants that have grown in front of the inlet.
- Follow the weather reports.
Not only with water, food and climate measures you can prevent heat stress. Also in the area of housing and with lighting you can make it the chickens easier during hot days.
- Avoid dead corners in the barn. If necessary, use additional fans to set the air in dead spots.
- Adjust the occupancy in warmer periods and start unloading sooner.
- Provide dry litter.
- Be sure not to open doors during warmer periods. As a result, the under pressure is lost.
- Water sprayers are of no use on an isolated roof.
- During the hottest period of the day, dim the light to reduce feed intake and body activity.
- To activate the chickens to drink water and to get rid of the heat under the wings, it is good to give the chickens a little more light every now and then.
- Adjust the lighting scheme so that there is no long dark period during the night.