Blue Light Benefits for Pregnant Mares – New Research

The horse’s natural reproductive period coincides with the light-filled days of summer.  The desire to breed mares early in the year means that many foals are born at a darker time of year than Nature intended. This has consequences for breeding efficiency. Often, early foaling mares experience longer gestations, have smaller foals and can have trouble cycling post-foaling.

As well as hormones that control reproduction, lengthening daylight stimulates important growth hormones that allow foals to mature in utero and mares to produce more milk and good colostrum. Specifically, it is the blue light wavelengths from the sun that drive these seasonal hormonal changes.

Published scientific studies confirm that extending day length for dry mares using blue light from Equilume Light Masks advances reproductive cycles as effectively as stable lighting, with the bonus that mares can be kept at pasture. For pregnant mares, extended daily light from light masks was shown to prevent prolonged gestations (reduction of 10-15 days) and optimise foal birth weights (average 4 kg increase) and foal maturity while improving post-foaling fertility.


New research presented earlier this year at the Equine Symposium at the British Society for Animal Science’s 2021 Virtual Conference showed that pregnant mares wearing blue light masks in the final 100 days of gestation had shorter pregnancies, earlier post-foaling ovulations and more mature foals at birth. The exciting studies, conducted by researchers at the University of Veterinary Medicine in Vienna, Austria also found that foals from mares wearing light masks in the final months of pregnancy stood 15 minutes faster after birth than foals born to mares that did not receive additional light.

The two-year study was conducted at the historic Brandenburg State Stud in Germany. The blue-light stimulated mares developed larger follicles in the late stages of gestation and could be bred sooner after foaling. Foals born from mares wearing light masks also had shorter hair coats, demonstrating that the light perceived by the pregnant mare is transmitted to the foal and influences their physical development in utero.

These new study findings show how correct light management of our pregnant mares can improve breeding efficiencies similar to Nature, but still allow foaling earlier in the year to fit with industry timelines.

Read the full research article here:

The Equilume Belfield and Curragh Light masks are specifically designed for breeding stock to receive ‘long day’ light signals when they are maintained outdoors at pasture.  The Equilume Stable Light system has a specific breeding programme which provides ‘long day’ blue enriched light by day which dims to red light at night to encourage rest and recovery while facilitating night time management routines without compromising a horse’s internal circadian rhythms.

For barren mares, blue light treatment should begin approximately 70- 75 days in advance of when they are required to cycle and for pregnant mares 90-100 days before their due dates.  For optimum results, the mask should remain on until the mare is scanned back in foal.

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