Dark nights for dairy cows

The light environment is a fundamental part of animals’ experience of their immediate surrounding and it is well established that lactating cows benefit from 16 hours of daylight and 8 hours of night. However, the most suitable light intensity for cows during nighttime has not been thoroughly investigated.

Recommendations on the night-time lighting regime on dairy farms differ between countries and range from light throughout the night to requiring a rest from artificial light.

In Sweden, light during the night is required but detailed specification on light levels lacks, both for day and for night light.

A dark period is important to maintain circadian rhythms and disrupting it might not only affect milk production but also health and cows’ natural behavior.

The aim of the project presented here is to establish recommendations for light in dairy barns at night, both regarding light intensity and the duration of the night.

This will be achieved through two experiments; 1) an obstacle course trial, testing the cows´ ability to navigate unknown environments in the dark and in low light intensities and 2) a night length trial were three different night lengths are tested and the effect on cow activity, feed intake and endocrine factors are measured.

Collectively, the project will provide new knowledge on dairy cow vision and management of night light in loose housing systems in order to secure natural diurnal rhythms in dairy cows.