Artificial light boosts hen egg production

By Ken Koelkebeck

This time of year I get phone calls from small flock and backyard egg producers regarding why egg production of hens is going down. This is a common phenomenon during this time of year.

First of all, there are two environmental things happening. At this time of year, the natural day length has been declining since the longest day of the year, which was June 20. In addition to this, the outside temperature is becoming cooler. Both of these factors play havoc with hens laying eggs.

Before we explain why these two factors play a big role in hens maintaining good egg production, we must discuss why hens react to these factors. First of all, laying hens are very photo responsive. This means that they need a constant amount of light to stimulate and maintain good egg production. There is a day length of light that is called the threshold of light, which is around 12 hours. Any exposure of hens to day lengths over 12 hours will make them come into production, and a day length that is lower than 12 hours will cause hens to cease egg production. So, during the months when the day length is lower than 12 hours, hens need to be exposed to longer day lengths by supplying artificial light.

Hens should be exposed to a supplemental light source in addition to the natural outside daylight. Typically, this light source should come on early in the morning and go off after the sun comes up; then come on 30 minutes before the sun goes down and off after a maximum of 16 hours of light per day (artificial plus natural). You can supply this light with a 100-watt incandescent light bulb, a fluorescent bulb, or even an LED light bulb to save on electricity.

The brightness of the light also makes some difference. Typically, if you have enough light to read a newspaper at arm’s length, then it is bright enough to stimulate egg production. It is simple to hook up your light source by using an inexpensive time clock. On days when it is cloudy, you should have the light stay on the entire day. It won’t cost that much in electricity to do this, and if you use an LED bulb, the extra cost would be minimal.

Another factor this time of year that causes egg production to decline is the change in outside temperature. Dramatic changes in temperature produce stress in the hens and will cause them to lay fewer eggs. If you have an insulated building that the hens can stay in when it is cold outside, this will help a lot. If you have a free-range operation and you want the hens to go outside, then they will be exposed to cooler temperatures and wind which will make them lay fewer eggs.

In summary, if you want to maintain good egg production in your laying hens during the fall and winter months, it is important to expose them to a long day/light length of 16 hours. In addition, it is advisable to try to maintain a comfortable temperature inside the chicken house and not let the hens go outside when the temperature drops considerably. If you keep these two factors in mind, then your hens should lay the maximal amount of eggs during this time of the year.

Ken W. Koelkebeck is a professor in the Department of Animal Sciences, University of Illinois, and an Extension poultry specialist.