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How does light impact milk production?

As information can change over time, If you read this outside of 6 months from the original post date, please confirm with your WCR advisor that the information is still valid and accurate.

Light provides illumination

Light is an essential but often overlooked aspect, especially for dairy cows. It plays a crucial role in both physiological processes and the behavior and productivity of these animals. Therefore, farmers should pay attention to providing the right amount and quality of light in the barn.

Here are some practical facts and tips to understand the importance of light for cows and how farmers can work on it effectively.

The importance of light

Cows, like humans, have an internal biological clock controlled by light. Exposure to light causes the animal to reduce the secretion of the sleep hormone melatonin. This results in an increase of another hormone, IGF-I, in the blood, which boosts the cow's activity and thus affects milk production, fertility and overall health.

Productivity and milk production

Research shows that cows regularly exposed to light have higher milk yields. Daylight not only increases productivity but also has a significant impact on vitamin D production, resulting in better absorption of calcium and phosphorus in the blood. Vitamin D is synthesized in the skin of cows when they are exposed to ultraviolet B (UVB) radiation from (sun)light. Cows need a minimum of 12-16 hours of daylight. A commonly used guideline is a light intensity of 200 to 400 lux at eye level in the barn. Since cows should ideally be lying down 12-14h per day, we need the 200 to 400 lux at the eye level about 2 feet high from the stall base level. Although it can result in inaccurate measurements, an easy way to measure this, is with a free app on your smartphone. If you wish to have a more precise and reliable measurement, our FMS team is equipped with lux meters.

Behavioral patterns

Light significantly influences cow behavior. A well-lit environment helps reduce stress and fear, cows show more natural behavior, which has a significant impact on their feed intake. In a well illuminated environment, cows eat regularly, which is essential for their overall health and increases milk production by 6-10%. Another article from OMAFRA goes into more details about "Lighting for more milk."

Read here:

Lighting for More Milk
Download PDF • 180KB

Artificial Lighting

In the case where natural light is limited, artificial lighting can be applied. The use of LED lighting with a color spectrum similar to natural sunlight is recommended. Light sources with mainly short wavelengths such as blue, green, and yellow have proven to be more effective in stimulating the biological clock of dairy cows.

Enough Light


Importance of light for cows:

  • Essential for cow welfare, physiology, behavior, and productivity

Biological clock and melatonin:

  • Light affects the biological clock, reduces melatonin and stimulates IGF-I hormone.

Productivity and milk production:

  • Regular daylight increases milk yield, affects vitamin D synthesis, and improves calcium and phosphorus absorption.

Behavioral Patterns:

  • Light reduces stress, stimulates natural behavior, regular eating, and promotes overall health and milk production.

Artificial Lighting:

  •  LED lighting with a natural color spectrum, especially blue, green, and yellow, is effective in limited natural light.

If you have any questions, please contact your FMS specialist.

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