There are minimum light levels required for both general inspection and welfare, respectively. Enhanced lighting levels may be required for stimulation of milk yield for the cows or for more visually demanding tasks for the stockmen. In such cases, higher lighting levels may have to be provided in some areas for a specific time.

Animal performance

Evidence shows that milkoutput and feed intake of lactating cows is highest with light periods of 16-18 hours per day and with a lighting level of at least 160-200 lux. 

Long day length would appear to alter the secretion of a number of hormones. Such hormonal shifts are not unique to cows and drive the commonly observed changes in reproductive activity in other species, too. Long days reduce the duration of elevated melatonin and produce higher secretion of the hormone insulin-like growth factor-I (IGF-I). Higher IGF-I is thought to increase milk yield.

On average, it is expected that cows on long days will produce an average of two litres more than control animals on natural photoperiod.

It is important to balance extended daylight with periods of darkness. However, light levels should be maintained around 30 lux to provide the cows with sufficient light to move around the building and exhibit normal behaviour with confidence.

Lighting applications


Lux level required

Colour rendering




Cubicle and feeding area

170-200 lux for photoperiod yield effect, 50 lux for general

Low to medium


Timed, with light level sensing. Fluorescents can use light level driven dimming

High pressure sodium, metal halide lights or multiple fluorescent fittings

Milking area

500 lux for pit


Very good

Timed with manual override

Fluorescent lights will punch light through the mass of pipes and fittings and give even shadowless light

Collection yard

50 lux

Low to medium


Timed with manual override

High pressure sodium or metal halide lights

Bulk tank area

200 lux




Fluorescent lights are most commonly used

Outside areas

20 lux

Low to medium


Timed/light level

High pressure sodium or metal halide lights are the best compromise between cost and performance


300-500 lux




Fluorescent lights are most commonly used

Providing 10-15% roof light area will be enough to provide between 100-500 lux through natural lighting, depending on the time of day and year. The key to sustaining this is to maintain the cleanliness of the roof lights. Transparent wall sections are also effective. Naturally-lit buildings need to be well ventilated to counteract the effects of heat build-up from solar gain, and the proportion of roof lights fitted should be higher on north rather than south-facing roofs.

Lighting design

When designing a system, the following  points should be considered:

  • How the lighting is used on a daily basis and appropriate places for the switches
  • Grouping and switching the lights in banks may provide different lighting levels
  • Lights should be positioned to allow them to be easily cleaned and the bulbs safely changed
  • Consider reflectivity of roofs and walls. Colouring surfaces white or a light colour can increase the lighting level dramatically
  • Fittings in most cases will have to be water and dustproof. Make sure the ones you choose are up to standard.

The number of lights required in any particular area will be determined by the type of light chosen, its wattage, the lighting level required and local conditions like reflectivity of surfaces and room size.


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