LIGHTS
Sodium, green, blue, cool or
warm-white light?
Good light is of utmost
importance for optimal
production conditions in poultry
meat and eggs. Light is a
necessity of life. Healthy
well-fed birds would weaken and
die if they were kept constantly
in the dark. But is any type of
light good enough?
By Henk Rodenboog, Pluimveepraktijk
Noord&Oost, Slagharen, The Netherlands
N
ormal light consists of different
colours. A rainbow shows this very
clearly. It separates, like a prism, the
white light in colours that only than can be
recognised by the human eye. Over the years
we have learned to understand that these
colours have specific effects on our moods
and well-being. The same counts for animals. Chickens for example also respond to
light. Their behaviour and performance can
be manipulated by the use of specific
colours, especially those with long waves,
such as red, orange, yellow, green and blue.
In 1986 USA researcher Marc O. North compiled a diagram in which he showed what influence these colours have on specific bird
characteristics and behaviour (Figure 1).
Sodium light improves the birds wellbeing
Figure 1. The relationship between light colour and production characteristics
Light to see
The intensity of light is expressed in lux,
which is the standard unit of illumination,
equal to one lumen per square meter. Young
chicks need plenty of light to find water and
feed. 30 lux is quit a common advice. After
several days, birds become well trained and
less light is needed. Older birds can do with
5 lux, to reduce their activity and energy use.
The light intensity in a poultry house varies
greatly, and largely depends on the number
of lamps, the type of lamps used and the
birds’ distance to the light source. To know
how many lamps are needed to meet the 30
lux requirement one should go by the rule of
0.8-1 Watt per sq. m. for fluorescent (strip)
light and 3 Watt per sq. m. for bulbs.
Light for meat and egg production
Wild birds respond very much to seasonal
changes. During the winter the quantity of
light is too low to continue with the production of eggs and growth. Only later in the
spring season is the light intensity sufficient
to resume production. Pullets however do
not only respond to the amount of light but
also to the length of the light period. When
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the day-length is shorter than 11-12 hours it
will delay their sexual maturity and thus egg
production. This phenomenon results from
insufficient triggering of the hypophysis, a
small pituitary gland in the bird’s brain.
Under the influence of light this gland sends
out hormones to stimulate hens to become
mature and lay eggs. So the amount of light
is of major importance to rear young birds.
How high the amount should be is subject to
discussion. Most breeding companies provide clear indications in their manuals.
Disco effect
Fluorescent light fluctuates with the current.
In slow motion one can see that this light
source switches on and off 100 times per
second and creates a stroboscopic effect.
The human eye is too slow to recognise this,
but chickens can see this disco effect. There
WORLD POULTRY - Elsevier Volume 17, No 12. '01
Light spoilers made from plastic pipes connected to the strip lights reduce the stroboscobic
effect and improve the equal spreading of the light over the whole house
fect they lost their popularity. Inventive farmers
however discovered that
placing a reflector under
the lights by sticking
black tape on the light
tube the problem of wet
letter was solved.
Meanwhile new lights
have been developed and
can be used when old
strip lights have to be replaced.
Coloured lights
In recent years sodium
lights and coloured lightDimmable monochromatic lamps are available in different
ing systems have gained
colours
popularity. Sodium lights
often have two different
light sources connected
are strong indications that this effect influto one frame: a lamp of 50 and one of 70
ences the bird’s behaviour. The make, type
Watts. This allows switching on of 50-70 or
and age of this type of lighting also have an
120 Watts. The light is yellowish without any
effect. The flickering increases when a dimflickering effect and supplies about the same
mer is used, while cool-white strip light has
light intensity as strip lights.
a higher flickering effect than the warmColoured lights are often used to better
white strip lights. High frequent strip lights
manage the birds. Red light to reduce agdo not illustrate these negative effects begression and cannibalism in free-range laycause they go on and off 26,000 times per
ers and green/blue to enhance growth in
second, which is beyond the birds’ recognibroilers. It is advised to use green in the early
tion.
stage of growth while blue can be introduced
later to reduce the activity of the birds. The
Wet spots
advantage of this type of light is that the
The combination of stroboscopic effect and
light intensity is similar or a bit higher than
light intensity may cause wet spots immediwith common light sources, but is more
ately beneath the lights where birds do not
equally spread. There are also less shadow
like to be. They then may use these spots to
spots. Whether the claims of improved perlitter. Especially in the winter this may creformance are realistic under practical conate, because of the high humidity, cold and
ditions is not generally supported but it
wet spots and be a source of ammonia prohas proven to have positive effects on the
duction. In worst-case scenario, these spots
behaviour of the birds and the quality of the
may become connected and create one long litter. h
and wide strip of wet litter.Until a few years
(*Note: this article originates from a publication
ago it was frequently advised to make use of
written by Henk Rodenboog, in the in-house magawarm-white light sources. Later cool-white
zine “Veerkracht” published by poultry processing
was favoured since it was believed that it
company Storteboom)
better matched normal daylight. But since
these lights have the highest stroboscopic efWORLD POULTRY - Elsevier Volume 17, No 12. '01
www.AgriWorld.nl 23