A University of Georgia study found that longer illumination times during high seasonal temperatures improve large broiler welfare and output.
According to Brian Fairchild, PhD, a poultry extension specialist, research in six commercial poultry barns looking at air temperature, velocity, relative humidity, and deep-body temperature in broilers found an intriguing multifactorial process.
Small heat sensors were implanted within the body cavities of broilers in the research done by Fairchild and extension specialist Mike Czarick throughout the summer months.
For the largest birds, who are undoubtedly under stress during the warmest months of the year, "we were looking at deep-body temperature," Fairchild said. They operated fans constantly throughout this time to take the variable of air speed out of the equation.
What they found was that, when the nighttime temperature dropped outside, the birds' body temperatures actually rose. According to studies, what occurs in rats and people is the exact reverse of this, he stated.
They discovered that illumination, or the absence thereof, significantly contributed to this nightly rise in body temperature.
At twilight, Czarick observed, "the lights go out, the birds settle down, and their litter is like a warm blanket." In addition, a bird's surface area that may be cooled by air movement diminishes when it is sitting.
The eating habits of the birds are a crucial aspect of the dark time.
The birds will consume the same quantity of food each day, so extending the illumination duration will give them more time to eat and spread out the digestion process, which also generates heat, according to Fairchild.
The birds cease feeding and rest until the lights are put on again if the lights are turned off at sunset. The birds start eating and drinking a lot as soon as the lights come back on, which raises their body temperatures throughout the day.
"The larger the gap in body temperature, the longer the dark time," he stated.
Czarick claims that during the day, producers focus too much on bird temperature.
"The important factor is how much the nighttime bird temperature is impacted by the illumination scheme. What matters most is how birds behave.
He said, referring to modern low-energy LED lights, "A few additional hours of power use is hardly significant." However, leaving the lights on until after midnight or till dawn has a significant influence on the health and comfort of birds.
