Body temperature, oviposition, and food intake in the hen during continuous light

Deep-body temperature of the laying hen was measured with an implantable radio transmitter. Food and water intake and oviposition time were recorded, remotely, based on electric signals from microswitches attached to the individual cages. Body temperature and feeding activity of the laying hen under continuous light displayed a circadian rhythm. The length of the body-temperature cycle was 25.2 h, and the feeding cycle was 25.3 h. These values appear to be associated with the animal's laying cycle which was 25.3 h. The laying cycle of the hen can play an important role in the maintenance of circadian rhythms of body temperature and feeding activity. Both the marked temperature rise found at the time of oviposition and the prelaying (or nesting) behavior may be controlled by a preovulatory surge of luteinizing hormone (LH) and progesterone.