With meat chickens (broilers) protection from the elements not only means sun and rain, but also a place of refuge during hot weather.
Conventional fast growing broiler strains suffer increased mortality rates during periods of hot weather, due to the excessive muscling and fat they carry around their breast and body cavity, particularly if their body weight exceeds approximately 1.5 kg. It is obvious therefore, that the pastured chicken farmer using conventional broiler strains must be extra vigilant, and any structure that houses their meat birds should ideally be able to keep the temperature below 300C, not an easy task with our hot summers in most parts of Australia.
It is worth noting that the intensive chicken industry aim to maintain a temperature between 21-240C inside their sheds. These producers rely on state of the art technology to maintain these temperatures, and modern broiler sheds are quite complex in their environmental management systems.
For small scale pastured poultry producers it is largely unviable to employ the same technologies to house broilers, particularly as the birds are free ranging, so a different approach needs to be taken. There is only a very limited area in Australia that is suited to year-round production of meat chickens using conventional fast growing broiler strains under non-intensive production methods. If you live in an area with summer temperatures consistently above 350C, then you probably will not be able to produce birds all year round unless you use alternative genetics. However, the following tips may be of some help to relieve the stress suffered by conventional fast growing broilers in Aussie summers .
Planning ahead is vital, as early or sudden heat waves are more dangerous than those which occur after several warm periods because birds become acclimatised to higher temperatures.
30 degrees celcius – food consumption starts to drop and water intake doubles.
35 degrees celcius – panting will have increased in intensity and wings will be held out and you will need to begin to assist birds with additional cooling methods, e.g. a fine mist spray from a hose.
Remember to move cautiously through the birds to avoid extra stress, and try to do the majority of your husbandry work in the early morning and late evenings.
38 degrees celcius – danger zone, birds lose the incentive to drink and crouch while heavy panting.
When the temperature rises further, birds can survive, but you must be vigilant.
The most vulnerable period during a heat wave is when nights stay hot. Birds tend to build up body heat during extended periods of hot weather. If their body temperature can be reduced during the evening, they will have a far greater ability to survive periods of extreme heat.
Assuming you lock the birds in their house at night for added predator protection, there must be enough space in the house to allow the birds to cool down in the evening, (approx.10 birds per square metre floor space ).
As well as the house being the right size: the house site, orientation, height, flooring, insulation and roof also affect the temperature inside the poultry house.
Where ever possible, poultry houses should be positioned under the shade of trees.
All houses should be designed to achieve good air flow, but also minimise the entry of direct summer sunlight. Large, netted open areas are important for air flow, with the flexibility to be closed in during the winter months.
Accumulated dust and manure may also restrict air flow and should be cleaned off.
Adequate insulation in the ceiling and sidewalls will pay dividends by reducing the amount of the sun’s radiant heat energy that reaches the interior. Some people place hay bales on top of poultry houses during heat waves for extra insulation.
Another factor that affects heat gain of a house is the condition of the roof. A shiny surface can reflect twice as much solar radiation as a rusty or dark metal roof. Roof reflectivity can be increased by cleaning and painting the surface with a reflective white paint or by installing an aluminium roof. These practices are particularly effective for buildings that are under-insulated.
The higher the roof, the less radiant heat on the birds during summer, and small openings at the top of the walls is important for the effective escape of rising hot air. Spraying the roof with water will also help reduce radiant heat.
Litter (wood shavings) on the floor of your pen can contribute to the birds’ well-being. If you provide a good depth of dry, friable litter, the birds will use it to keep cool by working their way down and spreading wings and feathers to expose flesh to the cooler material. Spraying the shavings with a very fine spray of water will be even better.
Keeping a reliable, clean, “COOL” source of water available to poultry is essential to help the birds cope with high temperatures. BIRDS WILL NOT DRINK WARM WATER.
Make sure all drinkers are kept clean and functioning correctly, and not blocked in any way. Avoid having permanent water pipes and hoses near the ceiling of the house, hot western walls, and lying above the ground, where the water will gain extra heat.
Lines in which the water has become warm should be drained to allow cooler water to reach the drinkers.
White coloured water reservoirs will reflect heat better than dark coloured ones.
If severe heat waves are predicted, you may want access to an emergency source of water should the primary water source fail.
Sufficient drinkers need to be available to accommodate all the birds at the one time, and they must also be adjusted to the right height for the birds and kept in the shade.
You may want to have a supply of ice blocks on hand to cool the water in the mid afternoon when temperatures are extremely high and the flock’s resilience is low.
Because the birds excrete electrolytes during periods of heat stress, electrolytes can be added to the drinking water to replace those that are lost and to stimulate water consumption. If a heat waves continues for more than one or two days, the birds get exhausted and their appetite is diminished, water soluble vitamins are also beneficial to replace nutrients quickly and help revive the bird.
Grass cover on the grounds surrounding the poultry house will reduce the reflection of sunlight into the house. Vegetation should be kept trimmed to avoid blocking air movement. Hosing the ground directly around the house will also help, as will directly spraying the birds, but this works best if there is air movement. Care needs to be taken to avoid excessively wetting the ground and the birds and creating high humidity which will make the birds more uncomfortable.