High-frequency versus
low-frequency fluorescent lights: Hens do not mind the flicker
T.M. Widowski and I.J.H.
Duncan
University of Guelph,
Guelph, Canada
Compact fluorescent lights
are considered economical replacements for the incandescent lighting traditionally
used in poultry houses. However, because the Critical Fusion Frequency
of chickens has been measured at 120 Hz, it has been suggested that the
birds may be able to detect the flicker of fluorescent lights powered by
standard magnetic ballasts, and that they may find the flicker aversive.
We measured the preferences of sixteen light hybrid laying hens for light
produced by fluorescent tubes powered by high-frequency ballasts which
flicker at 30,000 Hz over light from similar fluorescent tubes powered
by standard low-frequency ballasts which flicker at 120 Hz. The birds
were tested individually in a two-room testing chamber in which each
room could be illuminated by either light source. The spectral distributions
and levels of illumination in the two rooms were carefully matched and
both rooms contained feed, water, and a nesting area. Overhead video
cameras recorded the position and behaviour of the birds
during a 6-hour test
period on each of two days. The light sources in the rooms were switched
on the second test day to balance for any preferences the birds may have
had for chamber room. On both test days, the birds spent similar
amounts of time in fluorescent light powered by high-frequency and low-frequency
ballasts (P > .10). When data from both test days were combined,
the birds spent on average 44.8% of time in light from high-frequency ballasts,
48.2% in light from low-frequency ballasts and 7.0% in the central compartment
away from either light source. The frequency distributions of individual
activities indicated that the birds performed all activities in light powered
by both types of
ballasts. Although
the chamber rooms were nearly identical, the birds did exhibit a preference
for one of the rooms, spending about 80% of the time in it (P < .01).
We can conclude that at the illumination levels in this experiment, the
hens did not perceive the flicker of standard fluorescent light or they
perceived it but did not find it aversive.