Gradual vs. Abrupt Changes in Light
Abrupt changes (reductions in hours of light) create immediate drops in feed intake, body weight and feed efficiency. Although over time broilers will adapt their behavior (change their pattern of feed intake) in response to such a change, making gradual changes to the lighting program (both daylength and light intensity) is preferable. This is particularly important if birds are to be processed at younger ages. Under these circumstances birds will have less time to adapt to their eating and drinking behavior and so the effects on live performance will be more pronounced.
In addition to making gradual changes to the lighting program itself, making a gradual change to the state of night (darkness) or day (light) may also be beneficial. Feeding activity in broilers is at its highest level immediately after the lights go on, and for a period (of approximately 1 hour) before lights go off. The use of dawn to dusk systems (initiating day time or night time over a period of 15 to 45 minutes) will result in birds gradually moving towards the feeder and can help alleviate crowding