Management
Mimeo P-86
Poultry for Profit 
Cooperative Extension Service PURDUE UNIVERSITY Lafayette Indiana
Lighting the Layers
by Joe W. Sicer, Animal Sciences Department
Proper use of lights can mean more profit to you. Here are some suggestions on how to arrange and use lights advantageously.
The primary reason for using lights in the laying house is to stimulate egg production. It has long been known that light affects the chicken’s pituitary gland. This is the master endocrine gland of the body. It is located at the base of the brain just above the roof of the mouth.
Among other functions, this gland releases one hormone that controls the growth of the egg yolk and another that causes the follicle holding the yolk to rupture. This frees the yolk to start down the oviduct beginning the formation of the completed egg.
Much research has been done in recent years trying to find the most effective ways to handle light. It is evident that the extent and nature of exposure to light during the growing period can influence later egg production. It is also evident that the direction of a changing length of daily exposure to light is also influential. The possibilities of using a series of intermittent, relatively short light periods are still being studied. We do not have the final answer on how best to use fights. There are, however, many worth while facts on how best to install lights to serve the hens.
How Many Lights and Where
When installing lights, the first consideration must be for the chickens. It is the hen we want to stimulate. The lights must be placed so that all the birds will get an adequate exposure.
It is generally agreed that an intensity of one foot candle of light on the chicken is enough. This really is not very much light. You can measure the light intensity in your house with a light meter similar to the ones photographers use but calibrated in foot candles. Your electric service man probably has such a light meter.
In practice, one 25 watt incandescent lamp for every 200 square feet of floor space will give you an average of a bit more than one foot candle when the lamps are new and clean. In poultry houses, however, a 50 percent "use factor" should be assumed. Therefore, to be sure of always having at least the minimum intensity, 40 watt lamps are recommended instead of 25 watts. Use of brighter lamps is a needless expense so far as the chickens are concerned. In fact, lights too bright may encourage cannibalism.