How Can You 'Beat the Heat'?

Al Dam, Provincial Poultry Specialist and Sarah Buttle, Poultry Research Assistant, OMAFRA

It was a long cold winter, but now we have switched from trying to keep the birds warm, to hoping we can keep them cool enough. We are bound to get multiple extreme hot weather events this summer. This is always a challenge if a flock is late in their production cycle, as they are less able to tolerate heat at this time. The following article will talk about the way birds lose heat, barn environment and practical flock management techniques. All types of poultry possess five different methods with which they thermoregulate to stay cool:

  1. Conduction occurs when birds touch a cold surface, transferring heat from their body.
  2. Convection is when heat is pulled away from the bird using cool airflow and ventilation.
  3. Radiation occurs when the bird moves to expose less feathered areas of the body, releasing trapped heat and promoting water consumption.
  4. Excretion follows increased water consumption, where heat is released from the body via hot, wet feces and urine.
  5. Evaporation is the dissipation of heat through moisture into the air via guttural panting and increased respiration rate. Unfortunately, evaporation can have detrimental effects on blood pH, due to excess CO2 loss.

When a flock is in an extreme environment, with high heat and humidity, their metabolic heat threshold can easily become overloaded, putting the birds in danger. To manage this we must do two things: provide maximum cooling potential within the environment and reduce excess metabolic heat output.

From an environmental management perspective, we need to consider many factors: ventilation, water based cooling systems, shelter, water accessibility and barn density. Ventilation management differs slightly depending on the type of system used in barn. Natural ventilation is the most common system in organic poultry; it is reliant on wind through sidewall openings for air exchange. These sidewall openings should be sized to equal 5% of the floor surface area. In hot weather, curtains and chimneys should be fully open. Circulation fans can be added to ensure there is air movement during times with little or no wind, particularly in a wide barn.

Water based cooling systems such as high-pressure misters work to lower air temperature. The incoming air stream is passed through a saturated zone. Changing the state of water from a liquid to vapour requires heat energy, this lowers the temperature of the incoming air but it increases the relative humidity of this air. Although a less efficient method, running a soaker hose over the barn air intake can be used as a cost effective alternative to lower the incoming air temperature by a couple of degrees.

Coarse spray sprinklers are another water based cooling system that can be used. When used intermittently they can help to cool the birds by prompting them to stand and fluff up their feathers. This will help to release heat that is trapped under their body and the litter and get them to go over to the drinkers. During the sprinkler off cycle, as the bird dries, water is evaporated from their feathers, further cooling the bird. Great care must be taken with setting the on/off cycle times for these systems to avoid over wetting the litter. An alternative method for outdoor flocks would be to directly mist the birds with a hose, encouraging them to respond in the same way, releasing trapped heat.

With any water based cooling system, the capacity of the farm water supply must be verified to ensure there is sufficient water available for the birds drinking requirements, (which can double in hot weather), as well as the cooling system. Fresh, cold water should be available to the flock at all times, ensuring proper distribution so that all birds may access the drinker as needed.

Supplying shelter is absolutely necessary to provide shade and protection from the sun and extreme weather when birds are outside. Shelters should be large enough to cover the entire flock and sturdy enough to withstand various weather events. This is especially important if it is the only shelter available. Whenever possible, farmers may choose to bring the birds into a barn for added safety during extreme weather event. Shade trees are another excellent option for sun shelter, but make sure that they are not a raccoon latrine. These sites pose a risk to your birds and yourself for raccoon roundworm.

Figure 1: The Livestock Heat Stress App. is a free smart phone application developed to calculate the level of heat stress various production animals can experience. Based on factors such as temperature, relative humidity and species, it will calculate the Temperature Humidity Index (TMI), and provide realistic solutions for maintaining animal comfort and managing heat stress.

Figure 1: The Livestock Heat Stress App. is a free smart phone application developed to calculate the level of heat stress various production animals can experience. Based on factors such as temperature, relative humidity and species, it will calculate the Temperature Humidity Index (TMI), and provide realistic solutions for maintaining animal comfort and managing heat stress.
(Available for Blackberry and Android devices in English, Spanish and French)

Small pullets are able to regulate heat better than large roasters or turkeys, and densities should be adjusted accordingly. It is also essential that the farmer ensure adequate drinker accessibility for all birds. You might even need to look at whether you have enough drinkers with enough flow. For more information about water consumption patterns, see additional resources.

If you have waterfowl, a pond or small pool for swimming/wading can help them expel excess heat through their feet and bills. *Note* Do NOT give cold water to ducklings that are overheated- this will kill them!

With extreme hot weather additional weather situations can potentially lead to power interruptions. Without power, in hot and humid weather, in a power-ventilated barn, farmers can experience bird loss in as little as 3 minutes if the fans shut off. It is key to ensure the on-site generator is large enough and in good repair to support the complete and maximum function of all critical systems within the barn. This has to include your water pump. Make sure all aspects of the generating system are set up and ready to run in case of emergency.Managing the flock can be done before and throughout a heat wave using the following four recommendations:

  1. Pull Feed: This should happen early in the morning before the birds get a chance to have their first feed. Once it eats, it produces metabolic heat from digestion 3-5 hours later. If you feed in the morning, this falls during the heat of the day. Feed can be put down again in the early evening.
  2. Add Electrolytes: 1-2 days before an expected heat wave add electrolytes to feed or water, specifically potassium chloride which helps stabilize ion levels, restoring the loss from excretion and panting. To reduce blood alkalosis, reduce dietary salt and replace with sodium bicarbonate. Check with your certification body to make sure that any electrolytes you use will not affect your certification status.
  3. Walking the birds: In place of a coarse spray sprinkler, 'walking the birds' stimulates movement, releasing trapped heat in addition to promoting water consumption.
  4. Flush and lower waterlines/bells /troughs: To guarantee fresh cool water is available, flush the waterlines thoroughly. Furthermore, lowering the water nipples to the bird's eye level serves to promote water intake. Regularly clean bells and troughs to make sure the water is fresh to promote consumption. Remember that during hot weather water consumption for your birds can easily double.

You may be lucky enough to only face a heat wave when the birds are small, and encounter no complications during the summer crops. However, keep in mind that extreme hot weather can happen at any time from May to September and your luck may run out. There may also be challenges at the processing plant, even though conditions at the farm might be good for shipping. Work with your processor when this happens. Planning ahead this summer, including a contingency strategy, will be the smartest way to beat the heat.

Special thanks to Dr. Lloyd Weber, Dr. Mike Joyce and Dan Marshall

Additional Resources:

OMAFRA Heat Stress Fact Sheet:

Water Requirements of Livestock:

Heat Stress Livestock and Poultry Application:

For more information:
Toll Free: 1-877-424-1300