When you get too hot, it's hard to eat or do much of anything. The same is true for chickens. Chickens don't sweat. They pant and lift their wings to cool down.
Heat stress can cause chickens not to convert feed properly. This can affect a chicken grower's bottom line. And too much heat "can cause bird mortality," said Bill Dozier, a poultry specialist with the University of Georgia Extension Service.
Too HotIn fact, up until the early 1990s, the long, hot, Georgia summers caused havoc among poultry growers as chickens succumbed to the heat. But the use of tunnel ventilation in poultry houses has cooled the situation.
A poultry tunnel ventilation system pushes air through the house at about 500 feet per minute. That means the whole house's air supply is ventilated about every minute.
But when temperatures hit the high marks of summer, "it's hard to keep the chicken houses cool," Dozier said.
Cool It or ElseGrowers try to keep the temperatures in their chicken houses below 89 degrees Fahrenheit. That's the threshold. Temperatures above this can reduce chickens' weight, and growers are paid on weight gain.
"The less pounds, the less the grower's going to get paid," Dozier said.
Breaking the temperature threshold for extended periods can cause a 10-percent increase in the mortality rate, he said. That means even less money for grower.
Keep CheckDozier tells growers to check their ventilation regularly during the summer. Dust and dirt can reduce air movement, and worn belts and pulleys can reduce the ventilation efficiency by as much as 30 percent.
Growers have to watch for power outages, too. During a power outage, heat and humidity levels in the summer can reach lethal levels in 10 to 20 minutes, depending on the age of the chickens.
Chickens don't sweat. They pant and lift their wings to cool down.
BtusA single 6-pound chicken, just going about its day eating and growing, can produce about 90 BTUs (British thermal units) per hour. A BTU is a basic measuring unit of heat, the amount of heat energy it takes to raise the temperature of 1 pound of water by 1 degree Fahrenheit at sea level.
The heat generated by a burning blue-tip kitchen match roughly equals 1 BTU. "So, that's like setting a bird up on a table, striking 90 matches and letting them burn around the bird," Dozier said.
The heat coming off the chicken comes from digesting the feed it eats. It's like putting fuel in a car. The fuel makes the car run, but it also causes that car to produce heat. On an average day, as much as 80 percent of the heat generated in a chicken house comes from the chickens.
The average chicken house holds 24,000 to 26,000 chickens. But in the summer, Dozier said, some growers will put only 22,000 birds in a house.
With poultry growers' attentive help, chickens are able to cope with Georgia's wilting summers. Don't you wish you were?
(Brad Haire is the former news editor with the University of Georgia College of Agricultural and Environmental Sciences.)