Do farmers see their cows in the wrong light?

Author: Iain Dalton, (IfA) - January 29, 2018

Currently best practice management of artificial cow lighting in dairy barns is to ensure an 18:6 split with 160 – 200 lux at the cow’s eye during the longer light period. But as ever there is more to the management of cow lighting.








The use of automatic sensors and controllers can ensure this regime is easily achieved with little or no labour input, only occasional but routine cleaning and maintenance. A consistent 516% increase in output can be achieved and with capital expenditure in the region of £110/cow place installed a 7-9-month payback is realistic. Actual measurable benefit is likely exhibited within one month of installation as cows quickly adjust to the optimum regime. Careful design of system is needed and the hostile environment of dairy barns may require specifically designed drivers to avoid longevity problems.  

This basic situation with the 18:6 regime leads to increased output. However, within the bovine eye (as with other mammals) it is the retinal ganglion cells (RGC) that control this rhythm and they respond differently to light of different wavelength.

It is this characteristic that brings an added dimension to light design in barns. RGC respond to a greater degree to blue light (wavelength 400nm) than to red light (700nm) and therefore respond better to light produced from artificial lights with a higher proportion of low wavelength visible light.

As can be seen from the graphs here, the spectrum of lights can be very different, with many of the lighting systems used within dairy barns having low proportion or nil in the desirable blue spectrum.

Therefore, to ensure maximum benefit is achieved in lighting design, in addition to 18:6 split and 160-200 lux a light dominated by short wavelength light is vital. The solution is therefore to install LED lighting, however, although all LED lighting is energy efficient it is not all the same in terms of spectrum produced and the correct form of this lighting is required – warm white LED lighting has a higher proportion of high wavelength red light which is not as efficient in stimulating the RGCs,  cool white LED lighting  with its higher proportion of blue light is the most efficient and should be used in dairy barns.