During the summer, heat stress is a very real concern for poultry farmers. Whether you believe in global warming or not, it is not uncommon for temperatures in the Belgian summer to regularly exceed 30 °C. Combined with humidity, this can create very difficult conditions in poultry houses that have a major impact on welfare, growth and laying performance. It may be of greater importance to those rearing broilers, due to the higher stocking densities in the houses, but it can also affect egg production, so it makes sense for every poultry farmer to minimise the effects of heat stress.
What is heat stress?
Chickens experience ‘heat stress’ when they struggle to maintain a balance between body heat production and body heat loss. Heat is produced by the body’s metabolism – in a commercially reared bird, this means rapid growth and egg production. Chickens are able to regulate their own body temperature when they are in the ‘thermoneutral zone’, but as soon as the temperature rises, chickens must actively shed excess heat by panting. Slow panting is a normal activity and can be sustained for prolonged periods, but if this turns into rapid panting, the chicken may get into trouble and suffer from heat stress.
Effects of heat stress
Heat stress has a number of effects on chickens, making them even less able to regulate their own body temperature. If the respiratory rate increases and/or remains high for a prolonged period, birds produce more heat. This causes them to become tired and even less able to cope with the conditions. A higher respiratory rate also leads to a loss of carbon dioxide and an increase in the pH of the blood plasma (known as respiratory alkalosis). This results in reduced feed intake, causing the chickens to weaken further and become less inclined to move around. This can be fatal, as birds need to move in order to drink. After all, water intake is essential, as they lose a lot of fluid when panting. It is also only by moving that the bird releases heat from under its wings.
What can be done about it?
Apart from changing the design of your barn – looking into better insulation to keep the heat out and improved ventilation and cooling systems to bring cooler air in – there are a few things that can be done in any barn to reduce the risk of heat stress.
Space
Creating more space for the chickens is a natural solution. If possible, reducing the flock size before a heatwave can make conditions more comfortable for the remaining birds.
However, as soon as the flock begins to suffer from heat stress, care must be taken to ensure that no activities are undertaken that cause additional stress. Many farms also restrict access to the barn during these periods to avoid further stress factors. Raising the feeding troughs can also provide the animals with more space.
Air
Circulating cooler air is another solution. If the animals are very still and do not move away from the carer, or if they are hanging their heads, it is probably best not to disturb them further – they are already stressed. Ventilating as much as possible in the morning can help the flock get off to a cooler start on a hot day.
It can be difficult if the warm temperatures persist into the night, as lying in hot, damp bedding (often 32°C or above) offers no relief whatsoever and only makes them feel even hotter.
Nutrition
Although environmental management plays the most important role in managing heat stress, the targeted use of specific supplements is essential to help the chickens get through this period. Heat stress has a direct effect on appetite and the animal’s ability to utilise available nutrients, making it less able to recover – effectively a downward spiral that needs to be reversed. It goes without saying that the flock must have access to a plentiful supply of clean, cool water at such times, but a feed supplement such as Refresh can be remarkably effective in alleviating heat stress when added to the drinking water.
Refresh L can be added to the water on the first day of an expected heatwave as a preventative measure, or used to give a boost to a flock that is already starting to suffer. It can provide a much-needed boost for flocks that are starting to decline.
Electrolytes (sodium, potassium, chlorides and calcium) replenish the nutrients and minerals lost during extreme heat and stress, stabilise the blood’s pH level and boost immunity by supporting kidney and liver function. They also promote water absorption and replenish the body’s salts lost during dehydration, whilst further helping to stabilise blood pH, which becomes disrupted during stress.
Energy helps to reduce recovery time during periods of stress, enabling the chickens to perform at their best again as quickly as possible.
Citric acid promotes the absorption of glucose, which helps to provide the energy needed for recovery.
Vitamin C helps to reduce and alleviate the physical symptoms of stress.
Given that factors such as barn design or ventilation are difficult to influence, a feed supplement such as Refresh is invaluable. It is easy to administer and dissolves readily. It is therefore a very simple step to take to protect the welfare of a herd during a heatwave and maintain performance levels.
Recommended dosage: 1 kg per 1,000 litres of water, to be added to fresh drinking water from midday onwards as soon as the daytime temperature exceeds 30°C.
