Breads of domestic chickens selected for high egg production will begin egg laying if they reach maturity during either spring (increasing day length) fall (decreasing day length). However, chickens raised during the spring reach maturity and begin laying at earlier ages. Egg size is reduced when smaller, younger chickens begin laying, so producers often manipulate photoperiods to delay the beginning of laying until birds are of an appropriate size. After laying has begun, reductions in photoperiods will lower egg production, as compared to egg production with a constant photoperiod.