Why should light be controlled during the rearing period of meat-type breeding chickens?

The purpose is: to use a short or gradually shortened light period during the growth stage of meat-type breeding chickens, or to combine it with restricted feeding, so as to control the timely start of laying in young hens; as laying approaches, gradually extend the light duration and progressively increase stimulation so that they reach the peak of egg production at the proper time, while avoiding prolapse of the cloaca in some hens caused by a sudden increase in light duration.