COLUMBUS, Ohio – Stress in poultry can stem from such things as toxins, pesticides, fungicides, herbicides, chemicals in the air, feeds, water and cleaning agents. But according to experts, heat stress can cause more harm to poultry than all of the above.

Each summer, U.S. poultry producers lose upwards of $165 million due to heat stress. Research shows proactive management practices and timely support can reduce the impact of heat stress on flocks and profits.

“The key is to tackle heat stress in advance, through multiple strategies, because once poultry succumbs to the effects of heat stress, producers cannot recover those days of lost production and growth efficiencies,” said Dr. Bob Stock, a poultry nutritionist.

Stock is director of research and development at Ralco, a third-generation, family-owned multinational company based in Marshall, Minn. Ralco is a leading global supplier of livestock nutrition, animal health products and technologies that support poultry, livestock and aquaculture. Stock has more than 30 years experience dealing with poultry and livestock issues.

“Heat stress occurs when heat and humidity reach temperatures beyond a bird’s ability to thermally regulate their body temperature,” he explained. “The results can be devastating as birds will cut down on anything that requires energy, including water and feed intake. In addition, their egg production slows and growth is reduced.”

According to Stock, when a hen is too warm, she needs to lose heat. She does this by convection, which is losing body heat to cooler air by spreading her wings. Another is by evaporation. Moisture from the respiratory track has to be used, causing hens to pant. This increases airflow over mucous membranes.

“Panting is what leads to poor shell quality as they’ll be thin, weak shells,” Stock said. “And, if panting is not effective and body temperature further increases, the hen becomes listless and may die.”

Producers should avoid disturbing the birds if they are at risk of heat stress or are already overheating, he said. Any work performed abound the birds should be done in the early morning or late evening when it’s not as hot.

Jean Sander, senior technical services veterinarian with Zoetis, in Parsippany, N.J., cautioned not to overstock cages. “Birds need to spread their wings to increase airflow around their bodies,” Sander said. “If layers have to be moved on a hot day, place fewer in each transport crate and intersperse those crates with empty crates for better air circulation.

“With hot weather approaching, it’s time for layer operations to make sure they’re prepared to prevent this heat stress. A recent study from Purdue University and USDA’s Agricultural Research Service shows that heat stress is associated with 31.6 percent reduction in feed conversion, 36.4 percent reduction in egg production and 3.4 percent reduction in egg weight. There is also reduced breast meat quality. And there are other consequences of heat stress, such as increased water intake that can lead to wet manure and soiled eggs, and reduced immune function, which can impair vaccine efficacy.”

Ventilation is critical, both warn. Producers should make sure fans work well, that blades and louvers are clean and belts are properly adjusted for both tension and alignment. Stand-by generators and alarm systems are essential equipment for preventing heat stress. At times when summer temperatures are extremely high, roof sprinklers may be needed.

Water system maintenance is vital, too. At normal temperatures, 10,000 layers will drink 2,000 liters of water daily, but their intake will increase by 50 percent if temperatures rise to 90 degrees. Smaller operations, they say, should still take such precautions.

“Water intake is essential during heat events,” Sander said. “Research suggests adding electrolytes, probiotics and essential vitamins to the water 24 hours prior to a heat event. Probiotics maintain the balance of beneficial bacteria in the digestive tract during normal daily production stresses. They can also be used to restore beneficial bacteria lost during challenges, like disease or the flushing that occurs with heat stress.”

Stress on poultry comes in various forms: bird shows, traveling, excess noise, bathing, environmental changes, predator attacks, insect infestations, vaccinations and breeding issues. But stress related to heat is atop the list and can be controlled often

“Heat stress or not, we ask a lot of these production birds,” said Dr. Jessica Fox, director of Veterinary Services and Biosecurity for Ralco. “They are bred to apply all their energy to meat or egg production. We need to do all we can for them.”