From an article in LED magazine:

“Michigan State University has announced the results of a long-day lighting (LDL) research project at Wing Acres Dairy in Barry County, MI. Researchers from the school's Biosystems and Agricultural Engineering Department worked with the Michigan Milk Producers Association (MMPA) to study the implications of LED-based LDL on milk production, and the study indicates an 8% increase over the course of a year.

In the dairy research, the team sought to practically validate the LDL principles that have been studied for more than three decades. LDL consists of lengthening that daily light photoperiod to which dairy cows are exposed. Specifically, LDL research has shown better production when herds are exposed to 15–20-fc of light for 16–18 hours, followed by 6–8 hours with light levels below 3 fc.

In the past, Michigan dairies have been unable to fully realize the projected benefits of LDL because of limitations in legacy lighting systems. There have been technical difficulties in installing a system with accurate metering for light levels and precise control of output. But LED-based lighting, sensors, and an automated control system created by the research team overcame the aforementioned challenges to accurately deliver an LDL environment at the 100-cow Wing Acres operation.

The team studied production over the course of 2014 and documented the 8% increase in milk production. And the team sought to document other factors over the course of the year that could have impacted production. For example, the team compared operational practices on the farm to prior years and weather patterns, but found no significant factors outside of the LED lighting that could be responsible for the increase. The team concluded that "the increased milk production at Wing Acres Dairy can be attributed to the LDL system."

The diary had previously used metal halide (MH) lighting in its barn. The LED lighting is delivering significant energy savings as well as better-controlled lighting. Energy expenses for lighting are down 50%. Combined with the increased milk production, such an energy-efficient SSL project will deliver payback to a dairy in just over one year.

The dairy has noted several additional benefits to LED lighting. With MH systems, separate fixtures were required for the low-light period. But the LED fixtures can be dimmed to deliver the below-3-fc level required. Moreover, the LED fixtures are more reliable in the relatively harsh environment and will require much less frequent maintenance, which disrupts the dairy operation. Anecdotally, the farmer also said that the cows seem more docile after the retrofit.”



From the Manitoba Co-operator:

“Lighting experts suggest the correct light intensity and duration can have positive effects on the health, fertility, welfare and productivity of dairy cattle.

The lighting in your barn may be having more of an effect than you realize.

“The livestock’s biological clock is regulated by light and its effect on the pituitary gland in the middle of the brain. A lack of light depresses metabolism and causes increased melatonin output. We see this effect in the shorter days of winter,” said Andrew Hannon, an expert… that specializes in lighting livestock barns and agricultural buildings.

Research has shown that a well-lit barn can both boost your bottom line by reducing energy costs and increase milk production. “The benefits of proper barn lighting are that we can simulate and achieve a natural rhythm for the livestock in the barn. We want to manipulate that day, night rhythm,” Hannon said.


Additional Information



Independent research on the effects of lighting on dairy cattle began in 1978 at Michigan State University where researchers placed one group of dairy cows into 16 hours of light, followed by an eight-hour period of darkness and another group that was left at a natural light period during calving.

The study was conducted between September and March and it took place over the first 100 days postpartum. Cows on a long day regime produced two liters per day more milk than those on the natural photoperiod.

At 100 days the treatments were switched. The cows previously on a natural photoperiod increased in milk production when brought in to the long day light, where those that were on the supplemented lighting decreased their milk yield.

The results suggested that exposure to long day lighting increases milk yield and it does so across the production level.

Since this initial study, a number of similar studies have been conducted in North America and Europe and the response has been confirmed, the correct light intensity and duration have positive effects on the health, fertility, welfare and productivity of dairy cattle.

Researchers have found that light impacts hormone levels in cows and can increase milk productivity by 15 per cent.

Based on those studies, the recommended long day lighting for both milking cows and growing heifers is a light intensity of 150 to 200 lux over a 16-hour period, followed by an eight-hour dark period with a light intensity less than 50 lux. recommends full darkness for 8 hours each night. If any light is present it should be red light only. We also offer a special light which dims to red before dimming to off, if your operations require some light at night. (See our Products page.)

This lighting equation (referred to as long photoperiod) simulates long summer days, the days the cow is naturally the most active, resulting in higher yields and higher feed intake.

With an increase in feed intake, and an adequate rest period that long photoperiod lighting provides, the overall health of the cow is usually improved as it is less stressed, which in turn helps improve fertility and milk production.



What to consider

When looking at your facility and its lighting, there are a few things to take into account. Is the interior of the barn a reflective material? Plywood or concrete may require more lighting. Different areas of the barn may require different light intensity.

Veterinarian areas require intense light levels because of the inspection required, whereas your feed alleys and sleeping pack areas require less light than veterinarian areas.

When positioning lighting, it is best to watch for posts, beams or anything that may cast irritating shadows.

You do not want to put lights above ceiling fans. You will in effect create a strobe light, which is unsettling for, not just cows, but also all other livestock and people as well. Do not put lights over fans.

When looking at different lighting options, LED lights are the most popular in agricultural buildings because of the low energy use with virtually no maintenance.’s Dairy Lights are rated IP68 which allows them to be used in wet environments. And they are designed to withstand the chemicals often used as disinfectants in livestock areas. With the Daylight Harvesting of controllers, the systems generally consume less power than equivalent standard LED farm lighting.

By providing interior photographs, floor plans, and desired mounting height for the lights (normally about 15 feet), can design the exact lighting system required for the application, which shows locations for each light.

100 lux of our Dairy Lighting reduces melatonin as effectively as 200 lux from a white (6000K) LED light source.

Note: Non-lactating pregnant cows perform better using a regimen called Short Photoperiod. So if economically feasible, the farmer may benefit by housing these cows separately and using the Short Photoperiod mode in the Controller for the lights in those areas.


Increase milk production with long day lighting

Increase milk production and reduce energy consumption with long day lighting


Using light emitting diode (LED) lights, automated sensors, and an automated control system, a LDL system was created at Wing Acres Dairy that successfully resolved the technical difficulties encountered by Michigan dairies.

January 13, 2015 - Author: M. Charles Gould , Michigan State University Extension, Aluel S. Go

Research over the past 33 years has shown that long-day lighting (LDL) has a significant positive impact on milk production in dairy cows. LDL refers to increasing the daily light photoperiod for milk herds to 16 to 18 hours at intensity of 15 to 20 foot-candles of light, followed by a dark period of 8 to 6 hours of three foot-candles or less of light. However, Michigan dairy farmers have been unsuccessful in attaining the full benefits of LDL due to technical difficulties in measuring/maintaining light intensity and appropriately controlling the lighting system.

Wing Acres Dairy LED long-day lighting project

In cooperation with the Michigan Milk Producers Association (MMPA), a long-day lighting project, funded by a grant from the Michigan Energy Office, was initiated by Biosystems and Agricultural Engineering Department researchers at Michigan State University to address the technical difficulties referenced earlier. Using light emitting diode (LED) lights, automated sensors, and an automated control system, a LDL system was created at Wing Acres Dairy that successfully resolved the technical difficulties encountered by Michigan dairies. The LDL system has been fully operational since January 2014.

Wing Acres Dairy is a 100 cow dairy in BarryCounty. Over the past 12 months the dairy experienced an 8 percent increase in milk production. Two factors, farm operational practices and weather conditions, were examined to determine if the increased milk production could be attributed to LDL or something else. An examination of farm operation data from 2012 and 2013 indicated that feed quality, herd size, and animal husbandry practices did not change significantly. In 2014 no changes in management practices were made that affected the milking herd. The impact on milk production of last year’s favorable summer temperatures (i.e. cooler temperatures) was more than countered by the terribly cold winter. Based on MMPA data, member dairies had an average drop in milk production of over 9 percent during the February-to-March 2014 time period, more than negating any potential increase in milk production gained during the cool summer. A look at the 2012-2014 historical milk production records of Wing Acres Dairy showed that the so called “summer production dip” was absent, which is indicative of a well-ventilated cow barn, thus limiting the expected cool summer benefit since the cows were never stressed that much in the first place. One can reasonably conclude then, that the increased milk production at Wing Acres Dairy can be attributed to the LDL system.

Implications of the LED long-day lighting project

By replacing metal halide lights in the barn with LED lights, the owners anticipate at least a 50 percent reduction in lighting expenses. Based solely on increased milk production and with exceptional milk prices for 2014, a payback of just over one year is likely for the whole project. This project demonstrates that the technical difficulty of maintaining consistent light intensity and controlling the lighting system can work under Michigan conditions for small, average dairy operations. An accurate and reliable automated control system is the key to successful long-day lighting management. The calibration/modifications of sensors, monitors, programming and making the various components work together to make adjustments automatically in real time was the toughest challenge of this project. Anecdotally, the dairy farmer has noticed that cows in his milking herd have become more docile and less agitated.

LED lighting

LED lighting provides tremendous advantages over other artificial lights due to its low operating temperatures (82 to 113 degrees Fahrenheit), quick starting time (0 to 1 seconds), good color rendering (DesignLights Consortium required 60 plus color rendering index), long lifespan (over 50,000 hours), white color temperature (4,000 degrees Kalvin and above), lack of mercury in the bulbs, and little lamp lumen depreciation (90 percent and above). LED lights have the benefits of low maintenance, better directionality, high lumen per watt ratings, and good color rendering index (CRI). Additionally LEDs can be dimmed, eliminating the need for additional lights for use during the dark period. LEDs are the only truly dimmable lighting systems in the sense that a corresponding decrease in energy use occurs when the lights are dimmed. Other lighting systems can be dimmed but they still use the same amount of energy even though the light output is reduced. Additional saving in labor and maintenance can be attained due to the longer operational lifespan of LEDs.

Payback for LED lighting appropriate for farm use (dust, dirt, and water proof; physical impact resistance; and capable of extreme temperature operation) based solely on energy efficiency does not yet give a desirable investment payback under normal use due to the higher cost of these upgraded LEDs. However, energy savings combined with increased milk production through a well-managed LDL system makes the purchase of farm use LED lighting and the required control/sensor systems affordable.

Funding to implement a LED lighting system

Utility company rebates and USDA REAP and EQIP programs list LED lighting as an approved energy conservation practice. Michigan State University Extension recommends completing a Type 2 ASABE/ANSI S612 energy audit as the first step in securing funding to implement LED lighting. Information on energy audits and funding opportunities can be obtained at energy conservation meetings held throughout the state in January.

Questions concerning the Wing Acres Dairy LED long-day lighting system project, LED lighting and energy audits can be directed to Al Go at or 517-214-6128. Questions concerning the energy conservation program and energy audits can be directed to Charles Gould at or 616-994-4547.

This article was published by Michigan State University Extension. For more information, visit