Imitated natural light conditions during the artificial incubation may influence pullets' behaviour in being adapted to the diurnal rhythm.
To study these effects, eggs were set in a commercial incubator either in the dark control or under full spectrum light tubes (Philips TL95, 36 watt). To imitate the light changes by a clucking hen, the eggs were exposed to light for twelve hours a day with a light-intensity of 20 lux. After six hours there was a step-up in light intensity to 1000 lux for 20 minutes. After the incubation period, at day 18 of incubation, all eggs were transferred to the hatching compartments. After hatching, the chickens were reared in paired groups under Swiss organic standards. Each group, containing 1000 pullets, was observed at the age of 2, 4, 8 and 10 weeks in 5 trials. Several categories of behaviour, activity and the diurnal rhythm were observed (scan sampling). Hatchability per cent, mortality, weight and feather scoring at the age of 10 weeks were recorded.
There is no constant significance that light exposure during the incubation period affects the diurnal rhythm and behaviour of young laying hens. It seems to be, that the rearing conditions and management are still more important.
