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Heat Stress Prevention in Poultry

Small chick showing signs of heat stress with open beak breathing.

Technical Corner

Latest insights and information from our Technical Director

By Nigel Strain

Here in the UK and Europe summer has finally arrived, and whilst we all enjoy some nice, warm weather we must also be mindful of the challenges within our poultry houses’ environment. 

Small chick showing signs of heat stress with open beak breathing.

Record-breaking temperatures, as well as record-breaking production year on year, means that removing excess heat from our broilers is an increasing challenge.

Signs of heat stress

80% of the heat within a broiler house is produced by the birds themselves (metabolic heat) and birds have 3 methods of losing heat – conduction, convection, radiation. Once the body temperature climbs above the broilers’ normal range (40-42C) they will begin to show early signs of heat stress such as wing-spreading and slow panting and this will progress to faster panting as their body temperature increases further. If it reaches 45C and above, there is a high probability of death. It is therefore crucial that we manage to balance bodyheat production and bodyheat loss during periods of warm weather to protect the birds’ welfare and maintain performance.

Remove excess heat 

It can become difficult for a fully feathered broiler to lose enough of its body heat once the ambient temperature reaches above 27C and heat stress often affects broilers towards the end of the fourth week onwards when stocking density is at its peak making it challenging to remove excess heat trapped between the birds and litter. Carefully encouraging the birds to get up and move can help release this trapped heat.

Relative humidity

Relative humidity is also a key factor to consider along with temperature, as excess moisture in the air will mean the birds’ panting (evaporative cooling) will be ineffective in reducing their body temperature. Quite often, birds succumb to heat stress during the night, and the reason for this is that the RH is higher at night despite the cooler temperature.

The Heat Index is a useful tool – if the temperature in Fahrenheit and RH% adds up to 160 or more your birds will be suffering heat stress and will be in the danger zone.

Cooling equipment

Effective temperature is the key consideration, as with the right cooling equipment a bird can feel comfortable at high ambient temperature. For instance, a good tunnel ventilation system capable of providing at least 3 meters per second of airspeed consistently across a house of fully feathered birds will provide a great chilling effect of at least 6C and remove excess heat from the poultry house via rapid air exchange.   

Misting systems or cooling pads are also good options, especially in regions with low humidity, as they cool the incoming air which will drop the house temperature, but these can be challenging in humid conditions as they will cause an increase in RH% (around 5% per 1C of cooling).

Preparation is key

Being well prepared will help prevent heat stress issues – check your houses are well insulated, check that all ventilation equipment is working before they are needed, check the weather forecast at least daily, reduce the set temperature in the evening and at night to keep the birds cooler, helping them de-stress and catch up on consumption after a hot day (this will also help them to tolerate the heat of the following day). Adding electrolytes to the water system can also help during such stressful periods.  

I hope you all have a lovely summer and remember that the team here at OPTIfarm is always available to support you and your birds through it!