FACT SHEET
November 2011
How does lighting
affect dairy production?
FARMING connect
‘The aim of utilising lighting
to improve production is
to provide an ‘extended
period of light’. This can
be achieved by providing
cows with an intense ‘light’
period and a ‘dark’ period.
The idea of manipulating
artificial lighting to maximise
production is not a new
concept, but is seeing
renewed interest as farmers
look at alternative ways of
increasing production and
improving overall efficiency.’
How does lighting affect
dairy production?
Is lighting that important?
How does lighting affect production?
Figure 1 shows the results of ten studies1 examining the effect of
increased photoperiod on milk yield in lactating cows. These studies have
shown that dairy cows that are given a longer photoperiod i.e. 16 hours
of light each day, will increase milk production by between 5 – 16%
(an 8% response being typical).
Light reception occurs in the retina and both the
intensity and length of light exposure will control
the hormone response in the pineal gland. When
light is received by the eyes, a signal is sent to the
hypothalamus, which in turn sends a signal to the
pineal gland, inhibiting the production of hormones.
Benefits of a managed daily photoperiod include:
For an average cow giving 30 litres/day, expect an increase in milk yield
of 2.4 litres, meaning an additional 65p/day income
melatonin production
• Cows show maintained reproductive performance,
• Improved oestrus,
• Increased resting period, helping to reduce risk of lameness
due to increased lying times,
• Have set periods of light and dark; if you leave the lights on overnight cows will
revert to a winter setting. By implementing a managed lighting program you are
trying to re-create high summer all year round,
1
• The ‘light’ period should be 16 hours/day at > 162 lux2,
Dahl, G.E. & Petitclerc, D. (2003). Management of photoperiod in the dairy herd
for improved production.
Porter & Luhman, 2002
Miller et al., 1999
Dahl et al., 1997
• The ‘dark’ period should be 8 hours/day at < 54 lux,
• Ensure there is an even spread of light throughout the building,
Evans & Hacker, 1989
Philips & Schofield, 1989
Bilodeau et al., 1989
Stanisiewski et al., 1985
Marcek & Swanson, 1984
Peters et al., 1981
Peters et al, 1978
Milk (kg/d)
40
10
= milk production
Recommendations for artificial lighting
• Easier to observe bulling and early signs of ill health.
20
= feed intake
“It should be noted that the expected response time is approximately
four weeks following light installation.”
Figure 1: Ten studies examining the effect of increased photoperiod on milk yield
in lactating cows
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Longer day photoperiod =
• Increase in feed intake by up to 6%,
30
The pineal gland is important to consider when looking
at milk production, because this gland secretes melatonin.
In lactating animals such as the dairy cow, melatonin will
cause a reduction in appetite and reproduction levels
therefore less melatonin will lead to an increase in
feed intakes and associated milk production.
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• Ensure current lighting is clean and all lights are working correctly before
testing current light levels in sheds,
• Consider fitting timers and daylight sensors to switch off lights automatically,
ensuring lights are used when necessary, increasing efficiency and reducing costs.
2
Lux is the unit of illumination i.e. how bright the light is e.g. lux will be very low for dark areas
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How does lighting affect
dairy production?
Steps to improving lighting
1.First, determine the light intensity and duration currently available. It is
recommended that farmers invest in a light intensity monitor to check current
light levels across the shed before making any changes. It is also important to
test a number of areas across the shed at different heights from the ground
to get an average light intensity level.
2.If new lights are needed, determine which lights are best suited to the unit and
how many are needed per building. Use the following formula to determine how
many lights per building are required:
• Foot candle (FC): amount of light received by 1 sq ft of a surface that is
1 foot from a light source that is equivalent to one candle. In the equation
FC is the minimum intensity required for the lighting period (usually 15 – 20).
• K: a constant that accounts for light reflected in and escaping from the barn.
Use K=2 in enclosed barns and K=3 in open-sided cubicle buildings.
• Lumen (lm): unit of light flow, the measure of the total light output of the
light emitter. E.g. a lamp (energy of 1/683 joules per second, measured
at a wavelength of 555 nanometers).
Table illustrating factors effecting number of lights required per building
K
For enclosed buildings
K=2
For open sided
buildings
K=3
Foot candles (FC)
For Light Period
FC = 15
For Dark Period
FC = 1
Metal Halide Lamps
250 Watt
20,500 lumen
400 Watt
36,000 lumen
High Pressure
sodium lamps
250 Watt
27,500 lumen
400 Watt
50,000 lumen
Taken from: Wilson Agricultural Ltd (2011)
Which lighting is best?
There is a range of lighting available, including incandescent, halogen, fluorescent,
metal halide and high pressure sodium. The final choice will depend on the
mounting height and environmental conditions within the building as well
as running costs and environmental efficiency.
Number of lights =
Building area in square feet x foot candles3 x k4
Lumen5 output/lamp
Incandescent lights can be costly and have low energy efficiency.
Fluorescent lighting is often favoured as it offers high energy efficiency, reduced
lighting costs, longer bulb life as well as providing suitable lighting for livestock.
High pressure sodium lights also offer good energy efficiency and suitable lighting
levels for livestock, but reports have suggested that some people find it difficult to
see clearly with the yellow lighting. This issue is worth considering as it could affect
your ability to read freeze brands or tags.
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FARMING connect
Milking cows,
dry cows or both?
Research has shown that 16 hours of light and 8 hours of dark will
improve production in milking cows. However, some research has also
shown that a short photoperiod during the dry period could also
improve milk yields in subsequent lactations. Whilst the mechanism
by which this occurs is not fully understood, it is believed that there
is a greater response and sensitivity to prolactin during the transition
to lactation, which may be associated with an increase in subsequent
milk yield.
In most cases, it may not be practical to light buildings differently for
milkers and dry cows, so the emphasis should always be on creating
a 16 hour light period for the milking cows as it is this group that
has shown the most positive response to photoperiod trials.
Contact
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Phone
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website
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Improving lighting in stock buildings is simple and although it requires
a certain level of investment, payback periods are relatively short and
additional costs can be recouped due to the increased energy efficiency
of the new lighting system. Improvements are seen in milk yield and
reproductive performance as well as making tasks easier for staff to
undertake.
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It should be stressed that this is not a solution to all production problems;
but it will help to improve production as part of a whole farm approach
if nutrition, cow comfort, building design and other environmental factors
are addressed as well.
Farming Connect support,
guidance and training is delivered
by Menter a Busnes on behalf
of the Welsh Government
Author: Abby Cook, Kite Consulting
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