The effects of ahemeral light and dark cycles on growth and sexual maturity in chickens.

Replacement pullets were reared in environmentally controlled chambers in which the lighting schedule was 14L:7D, 14L:10D or 14L:14D. Both temperature and humidity were constant throughout the experiment. Neither body weight nor age at sexual maturity were altered by these lighting schedules. It was concluded that a unifying hypothesis to explain the various effects of photoperiods on growth and sexual maturity would probably not involve circadian rhythms.