When winter sets in and flocks start having problems, in most cases there’s one factor you can’t get around: temperature swings.
During the day, the sun heats the chicken house until it is too stuffy to stay in. Once the sun sets, the temperature drops, and the chickens tuck in their necks and fluff up their feathers. Everything may look fine today, but when you go in early tomorrow morning, you hear them snorting, and when collecting eggs, you notice noticeably more eggs with rough shells and pale-colored shells.
Many people’s first reaction is to quickly start medication. Respiratory medications, E. coli medications, and antiviral medications are used one after another. The money is spent, but the chickens may not get better. As soon as the medication is stopped and the wind blows, the problem comes back.
The approach is wrong. Temperature variation is the root cause; colds and egg drops are the consequences. If the root cause is not addressed, no matter how much medicine you add, it is wasted.
The China Animal Disease Prevention and Control Center states clearly in its winter and spring poultry disease prevention and control guidance: climatic stress is the primary risk factor. Frequent temperature fluctuations and large day-to-night temperature differences can easily cause cold stress in flocks, damaging the respiratory mucosal barrier and reducing local immunity, giving pathogens an opportunity to take hold. H9 subtype avian influenza and infectious bronchitis may not necessarily flare up under normal conditions, but when cold stress hits and the mucosa is compromised, they take advantage of the situation.
So that trick isn’t any kind of secret formula; it’s just keeping the temperature difference in check. But not many people can do that properly.
How much is the temperature difference held to?
The suitable temperature during the laying period for laying hens is between 18°C and 25°C, and the lower limit should preferably not fall below 15°C. What is truly harmful is not “cold,” but “sudden temperature fluctuations.”
Some sources clearly state that when the day-night temperature difference exceeds 8°C, the flock’s stress response becomes pronounced, feed intake declines, and the laying rate fluctuates accordingly. The goal of autumn and winter management is to keep the day-night temperature difference inside the poultry house within 5°C, ideally at around 3°C.
Why 5℃? Because the respiratory mucosa of chickens is extremely sensitive to sudden temperature changes. When hit by cold air, the movement of the tracheal cilia weakens, leaving a “gap” in the mucosal barrier. At the same time, chickens prioritize using energy to generate heat and stay alive, cutting the “budget” for follicle development and eggshell calcification. What you see is a drop in egg production and sandpaper-shelled eggs; the root cause is energy being consumed by temperature fluctuations.
Three key points to keep temperature fluctuations in check
Close the air inlets at dusk; don’t wait until the chickens hunch their necks.
Many poultry farmers run the fans and open the air inlets during the day, but get busy with other things at dusk and forget to close them. By the time they remember, the chickens have already been exposed to a cool draft for more than an hour. The right approach is to narrow the air inlets before sunset, giving the house temperature time to adjust gradually, rather than waiting until the chickens fluff up their feathers and then trying to fix the problem. The principle for ventilation in autumn and winter is “low airflow, short periods, multiple times.” Angle the air inlets so the air flows upward: the cold air should hit the ceiling first and then descend. Don’t let it blow directly onto the chickens.
At night, watch for drafts from sneaky air leaks—the leak is not at the main door.
In a chicken house, air leaks are often found in inconspicuous places such as exhaust fan shutters, cracks in the walls, and the edges of cooling pads. A draft is typically “a small stream of cold air blowing directly in one direction”; the cages it reaches are the ones most likely to develop problems first. Sealing leaks around the exhaust fans before winter sets in is the most cost-effective investment.
Ventilate at noon, raising the temperature first.
At noon, the temperature rises, and the ammonia smell becomes noticeable too, so ventilation is indeed needed. But the correct order in autumn and winter is to raise the temperature in the house first, then increase ventilation, rather than forcing ventilation at a low temperature. A strong ammonia smell does not mean ventilation is insufficient. Often, manure is not removed promptly or a drinker is leaking. Address the source first, then consider ventilation.
Once the environment is stable, it’s a good idea to build a little more resilience to stress.
Once temperature fluctuations are under control, the flock will be much more stable. During periods when cold stress is common—for example, two or three days before a temperature drop, or when a few chickens have just started showing occasional nasal discharge—many experienced poultry farmers make a point of providing some gentle nutritional support.
It’s not about using medication to plug the gap; it’s about giving the chickens a little more resilience against the cold. Cold stress can increase chickens’ vitamin requirements. Supplementing with appropriate amounts of vitamins C and E and electrolytes can help ease the stress response. The energy content of the feed can be raised slightly so the chickens have enough “fuel” to produce heat, rather than drawing on egg production.
That said, these measures are the “icing on the cake,” not a “lifeline.” If the temperature swings aren’t controlled and drafts aren’t blocked, it’s unrealistic to expect feed additives to turn things around after the chickens have already caught a chill. Get the environment right first, then consider supportive measures.
To be honest
After years of raising chickens, with medication costs rising, feed prices high, and egg prices fluctuating, every penny has to be spent where it counts. The most wasteful spending is when temperature differences aren’t kept under control, the chickens get chilled, and then medication is used to fill the gap. It may patch things up for a while, but it won’t solve the problem for good.
That trick isn’t magical: just close the vents a little more diligently than others in the evening, make one more round through the house at night, and keep the temperature difference within 5℃. Ask experienced farmers whose flocks rarely have respiratory problems in autumn and whose egg production curves stay steady, and most of them won’t tell you about any secret formula. It’s these seemingly insignificant tasks, done more thoroughly than by most people.
In autumn and winter, chickens aren’t afraid of the cold; what they’re afraid of is alternating between cold and heat. Once you understand this, you can save on medication costs and keep egg production steady—nothing is more practical.