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Lighting in cow housing - Long Day Light Period [LDLP]

According to research, optimum photoperiod will increase milk yield by 6-10% on average. 

  • Eventually, cows increase feed intake to support the risen milk yield;

  • No effect on protein or solids content while only a very limited decrease in fat content;

  • The increase in milk yield amply compensates the effects on fat and feed intake;

  • The cows are more active and fertile for extended periods when exposed to longer days;

  • Cattle with fertile periods that return faster, can lead to reduced calving index.

Why is there an effect?

Light reception occurs in the eyes retina. Light inhibits an enzyme used in melatonin synthesis in the pineal gland. Therefore, as photoperiod increases, the duration of high levels of melatonin in the blood decreases. Melatonin concentration in the blood influences the concentration of some hormones in the blood, for example, insulin-like growth factor-1 (IGF-1). Scientists believe changes in the concentration of IGF-1 play a role in the effect of photoperiod on milk production, as IGF-1 has been shown to increase milk yield.  IGF-1 is basically growth hormone, which directly affects production of milk in the udder.

Why should we be concerned with this?

• The use of light is cost-effective and has a very short pay-back time.
• Very simple to carry out.
• No extra labour required.
• Improved production and therefore margins on the units we work with.

Requirements for lighting:

For milking cows, calves and heifers:
16-18 hour long day photoperiod; 150-200 lx at the eye level of the cow
8 hour of uninterrupted darkness means less than 5 lx* at the eye level of the cow

3 months period per year:
16 hours long at less than 5 lx*.
8 hours of 150-200 lx
[this will reset the long-day photoperiod and improve the immunity system]
*5lx means that you can still see a printed text.

Red night lights may be used to facilitate cow movement and observation during darkness. This adheres to the dairy standards which state we must be able to inspect cows at all hours of the day and night. The red lights allow the operator to see, however the intensity of red light has no (or only minor) effects on the cows’ perception of darkness, and thus melatonin secretion.

There should be no brighter lights in any part of the barn and cows need 2-4 weeks on average to adjust.

Colours of lighting:

Lately there has been discussion on different colours of LED lights and their effects on cows.  Here is a summary of the conclusions of a recent study:

"Milk yield did not change during the trial and did not differ between the Red and Blue groups. In conclusion, sorting activity was greater during the daytime in the LED period, which could have been influenced by the LED light. Interestingly cows seem to have better vision in red than blue LED light. Furthermore, it also possible that the LED light maintains milk yield since no change was observed during the four-week trial in post-peak lactation."

to view this in full see here: 

To read the abstract from another recent study on blue light effect and the colour of LED's on cows, see here:

LED lights

Increasingly the importance of more efficient lighting is being considered.  Therefore, CowPlan are offering a fully tailored LED solution.  We have several options for LED lighting available, and utilise the best LED warehouse units on the market. 

Each building will have a survey and full lux scheme calculated.  This shows us where to locate each light and at what level.  We then use tailor made control panels to offer timing and lux sensors in the building.  All the LED's we offer come with a 50,000 hour, 5 year warranty.


Contact us now for a few  LED schematic and see what we can offer.


150W LED lights
LED cow shed light
Touch screen control panel
LED cow shed light
Luxum LED light
Cow housing lit by CowPlan


Working with Wilson Agriculture's own brand lighting, CowPlan is please to offer the AgriLux range of High pressure sodium lighting.

  • 250W or 400W option

  • Lighting schematic will show you the best option for your building

  • Photo cell, timed control panel and red light options included.

AgriLux light by Wilson Ag and CowPlan
AgriLux light schematic by Wilson Ag and CowPlan
AgriLux light by Wilson Ag and CowPlan
AgriLux lighting in CowPlan cow shed

Plan a cow shed  

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