How to Improve Summer Production Performance Through Environmental Management


Broiler Heat Production: Each Chicken Equivalent to Dozens of Burning Matches

A fast-growing broiler generates 10-15 Btu of heat per pound of body weight per hour. To put this in perspective, a burning match releases exactly 1 Btu of heat. This means:

A 4-pound (approximately 1.8 kg) broiler’s internal heat is equivalent to simultaneously burning 40-60 matches.

An 8-pound (approximately 3.6 kg) broiler’s internal heat is equivalent to 80-120 matches.

To maintain a normal core body temperature (approximately 106°F / 41.1°C), the broiler must continuously expel this excess heat. If heat dissipation is hindered, the body temperature will rise.


Elevated body temperature → Reduced feed intake → Slower weight gain

Why does elevated body temperature lead to reduced feed intake? Digesting feed itself generates heat. When a chicken’s body temperature is already high, continued feeding will further raise it, potentially reaching dangerous levels. Therefore, broilers will instinctively reduce feed intake to avoid overheating.

This phenomenon is strikingly similar to how humans experience a decrease in appetite during hot summer days. The result is: reduced feed intake → insufficient nutrient intake → slower weight gain. To maximize broiler production performance, it is essential to create an environment where the flock can easily dissipate heat.


Field Study: Negative Correlation Between Body Temperature and Weight Gain

A five-day field study (near market age) on 34-day-old broiler chickens clearly revealed this relationship. Researchers installed miniature temperature recorders (recording body temperature every minute) on eight broiler chickens in the chicken house and weighed them before and after the study.

Key environmental parameters:
Indoor air temperature: 23.9°C ~ 29.4°C
Wind speed at 1.2 meters (4 feet) above the flock: Approximately 2.5 m/s (500 feet/minute) on average

Results:
The average body temperature of the chickens fluctuated between 106.5°F and 108.8°F (normal is 106°F).
Two chickens with an average body temperature exceeding 108°F (42.2°C) did not gain any weight during the study period (one of them even lost weight).
The two chickens with the lowest average body temperature (approximately 106.5°F) gained the most weight, reaching approximately 1.3 pounds (0.59 kg).

Note: Initial weight was not significantly correlated with body temperature because the initial weight differences among the experimental chickens were minimal.


Common Causes of Elevated Body Temperature

The chicken with the highest body temperature in the study was found to have a mild respiratory infection. However, even without disease, the following factors can also cause elevated body temperature:

Excessively high ambient temperature (especially in summer)

Excessive humidity (hinders evaporative cooling)

Insufficient ventilation (heat cannot be effectively dissipated)

Overcrowding (heat accumulates between individuals)

Regardless of whether the elevated body temperature is due to disease or poor environmental heat dissipation, the flock’s response is the same: reduced feed intake → decreased weight gain.


Summer Management Core: Maximize Heat Dissipation, Not Worry About "Catching the Cold"

1. Two Main Heat Dissipation Methods

Wind Speed ​​Cooling:** Airflow removes heat from the chickens’ bodies (primary method).
Water Curtain Cooling:** Reduces the temperature of incoming air through evaporation.

2. Should Broilers Nearing Slaughter Be Worried About Excessive Cooling?

In most cases, no. The reasons are as follows:
* Slaughter-age broilers have stronger heat retention capabilities (fluffy feathers, air layers between feathers increase insulation).
* They can move closer together or fold their wings to reduce heat loss.
* Compared to the energy-intensive heat dissipation method of “panting,” the above heat retention measures are almost effortless.
* Therefore, the safer approach is to provide the maximum possible wind speed within 24 hours, rather than turning off the fans for fear of “catching the cold” at night. As long as the flock is capable of keeping warm, ventilation should not be restricted.

3. Higher Wind Speed, Lower Body Temperature, Greater Weight Gain

Research confirms that the more heat producers can remove from the flock, the closer the chickens’ body temperature is to normal levels, the higher their feed intake, and the more ideal their weight gain. In summer, increasing the airflow inside the chicken coop is the most effective and controllable way to remove excess heat.


Achieve Optimal Production Performance Through Scientific Environmental Management

Fast-growing broilers generate a significant amount of heat and must continuously dissipate it to maintain a normal body temperature.

Even a slight increase in body temperature (1-2°C) directly inhibits feed intake, leading to stagnant weight gain.

Disease, high temperature, high humidity, and low wind speed can all cause a rise in body temperature.

The summer management goal is clear: actively dissipate heat from the flock by increasing wind speed (and using water curtains if necessary).

Broilers nearing slaughter have strong heat retention capabilities, so there is no need to worry about excessive cooling; priority should be given to ensuring high wind speeds throughout the day.

By following this principle, you will help your flock maintain a stable body temperature, maximize feed intake and weight gain, and thus achieve excellent farming efficiency even in hot seasons.