With the hottest months of the summer approaching, backyard poultry producers need to be prepared to help their birds during the hot weather. Heat stress is a problem for poultry when the environmental temperatures and humidity rise above their comfort zones. Producers should be prepared to deal with the hot days ahead.
Poultry do not have sweat glands to cool their bodies like humans. They must relieve heat through other means. When the environmental temperature begins to rise, birds will use non-evaporated ways to reduce heat such as increasing surface area by relaxing their wings and hanging them loosely by their sides. Another non-evaporate means is to increase peripheral blood flow. The blood cools from being exposed to the surface before returning to the internal structures of the body. Once the environmental temperature approaches 85 degrees Fahrenheit, birds try to alleviate heat through open mouth breathing. This increases evaporative cooling or water evaporation. Other adjustments birds make to reduce heat are to decrease food intake and increase water consumption. Digestion of food creates heat. Drinking cool water cools the body internally. Birds will decrease movement to reduce heat production. Failure to prevent body temperature rise will end in death.
Many predisposing factors may lead to heat stress. One factor that might make some birds more susceptible to heat stress is genetics. Some breeds tolerate heat better than others. Older birds, heavy birds, and broilers are more prone to heat stress. Also, birds that are not acclimated to heat have more problems. Obviously, birds that have poor quality, hot, or no water will have problems tolerating hot days.
The clinical signs of heat stress are associated with the body temperature of the bird. As their temperature rises, the animals are reluctant to eat, they crouch down with their wings to their sides, and refrain from walking. As the condition progresses, they pant rapidly. Their combs and wattles become pale. They may have diarrhea from the increase water intake. During the final stages, they seizure and become comatose before death.
Complications that are associated with heat stress are respiratory infections and production problems. Open mouth breathing by-passes the immune system’s “filters” in the nasal passages that protect the respiratory system. Also, rapid breathing removes CO2 from the blood. This results in the blood pH rising which reduces calcium. Calcium is important for egg shell development. Low calcium levels result in thin shelled eggs. Other problems are associated with decreased feed consumption and poor feed efficiency. Birds that are too hot will not eat, and the little food that is consumed is not digested properly. This reduces protein and energy which results in lower body weights in growing birds. In layers, poor appetites result in small eggs, poor quality eggs, and fewer eggs.
Certain steps can be taken to prevent heat stress. Birds should have clean, cool water at all times. Producers need to make sure there is good air movement. A fan will help in keeping the air flowing on hot still days. Birds need shade. Make sure birds have plenty of space. Birds should be kept calm. Birds should not be harassed by dogs or other animals. Adding electrolytes to the water may help the birds during hot weather. Producers may want to freeze the electrolytes in an ice tray and add them to the water source. Electrolytes should not be used for more than three days. The addition of vitamins will help heat stress. The addition of vitamin C has been shown to prevent a decline in egg production and shell quality. Providing birds with a wading pool is good way to keep birds cool. Another trick to keep birds cool is to provide frozen treats. The birds will enjoy munching on some frozen fruits. Lastly, as stated earlier, digestion of food creates heat. Producers should alter the time that they feed birds to allow for the digestion to take place at the coolest part of the day.
Keeping backyard poultry cool during the hot summer can be challenging. Failure to keep the birds comfortable will result in dead birds at the worse or poor production at the least. Producers should consult with their veterinarians and/or Oklahoma Cooperative Extension Service County Educator for the latest information on heat stress prevention for backyard poultry.
(Barry Whitworth, DVM, is the area food and animal quality and health specialist for eastern Oklahoma for the Oklahoma Cooperative Extension Service.)