Modern broiler breeders have an amazing ability to convert feed nutrients for growth and egg production. Post-feed consumption, a hen’s body temperature increases rapidly (heat increment of digestion). Hens on slats post-feeding have been observed to be in some level of heat stress. Consequences of overheated hens include a decrease in feed intake or increase in feed cleanup time (delaying egg gathering pattern), decreased production, eggshell quality decline, and mortality. Any signs of heat stress should be addressed immediately.
A fan program, which is used to remove the metabolic heat, must be adjusted seasonally. Keep in mind that all fans are usually running in the summer by default. However, during the other seasons, additional fans should be used during feeding and throughout production. This program of increased ventilation post-feeding is most effective in the fall, spring, and winter. In the summer, there is usually adequate air speed.
Keep hens cool to reduce stress-related illness and mortality
In an early investigation, an increase in hen mortality was noticed and diagnosed as E. coli peritonitis. While investigating, it was discovered that days earlier, some of these hens appeared to have heat stress post-feeding. The hens were panting with wings stretched out, and the most severely affected hens were primarily on the slats. To alleviate metabolic heat stress, fans were turned on at the same time as the lights and continued to run until 2 hours after cleanup. These simple actions were effective in alleviating feeding-related heat stress and eliminating the associated mortality. While there are many reasons for E. coli peritonitis mortality that is not associated with heat stress or removing heat, in many cases, running fans to remove metabolic heat will decrease hen mortality.
This investigation revealed the importance of keeping hens cool as even a relatively short time frame of overheating can increase the mortality in hens days after the insult. Moreover, as noted, hens that experience metabolic heat stress can reduce feed intake or delay feed intake. A consistent reduction or delay in feed intake can cause declines in egg production, a delayed daily egg-laying pattern, a shell quality decline, and an increase in mortality.
Chickens rely on non-feathered areas of their bodies, such as wattles, breasts, and under the wings, to remove excess body heat. Hens do not sweat. This is one reason why birds may stretch out wings when they are overheated. Additionally, hens may pant to reduce body temperature, and with panting, hens may develop electrolyte and pH imbalances. Keep in mind that hens may increase their water intake to rehydrate. Therefore, it is important to always provide fresh, cool, and clean water and ensure that the water pressure in the drinking lines is sufficient.
Management actions
Create an environment inside the breeder house that allows the flock to remove excess body heat and remain comfortable. Providing good ventilation during feeding time will reduce metabolic heat stress and prevent a decrease in feed intake as well as reduce mortality. Panting birds post-feeding is an indication of heat stress and should be addressed immediately.
Temperature, airspeed, and humidity are components of an effective temperature the birds feel. Metabolic heat during digestion will increase body heat as hens feed. To alleviate the metabolic heat, run additional fans from the time feed is distributed until 2 hours after cleanup. Additional fans must be run automatically (through a controller) with careful oversight. The risk of failure is high if fans are initiated each day manually. Consider putting the fans on a timer with a thermostat override if there is no controller. Production may drop if the birds are too cool. Therefore, monitor the airspeed and effective temperature closely.
Benefits of a fan program
When hens are heat stressed, feed cleanup and digestion time increase. Moreover, egg production and eggshell quality can suffer as a result of heat stress. The benefits of using a fan program to keep hens cool during feeding include:
- Decrease in mortality.
- Decrease in E. coli peritonitis.
- Increase in egg production.
- Increase in eggshell quality.
- More eggs early in production.
- Improved digestion of feed.
Conclusions
Preventing heat-stressed hens during feeding will benefit producers by improving production performance and make flock management easier. Additionally, although we understand some of the impacts of heat stress on egg quality, there is more to learn. To further our understanding, we are currently conducting research to understand how heat stress can impact eggshell quality. Our findings will be communicated with producers and customers to benefit their production efforts and help flocks reach their full genetic potential.
About the author
Kevin Odenbach has experience in the poultry industry as a pullet/breeder technician, hatchery manager, and live production manager. At Cobb-Vantress, Kevin is a technical service advisor in North America. He holds a bachelor’s degree in poultry science from Texas A&M University.
