Blue light from individual light masks directed at a single eye advances the breeding season in mares.
Authors: Murphy B A, Walsh C M, Woodward E M, Prendergast R L, Ryle J P, Fallon L H, Troedsson M H T
Journal: Equine veterinary journal
Summary
# Editorial Summary: Blue Light Masks for Advancing Mare Breeding Season Photoperiod manipulation remains the gold standard for advancing the breeding season in horses, yet conventional approaches require expensive indoor housing with extended artificial lighting. Murphy *et al.* investigated whether low-intensity blue light masks worn by individual mares could suppress melatonin production and trigger reproductive cyclicity as effectively as traditional barn lighting, comparing 16 mares housed indoors under 250 Lux lighting, 25 mares wearing blue light masks whilst outdoors (activated 16:30–23:00 h daily), and 19 control mares under natural daylight conditions. By 10 February, oestrous cyclicity—defined by follicles exceeding 20 mm diameter, serum progesterone >1 ng/ml, and confirmed ovulation—was established in 87.5% of indoor-housed mares and 80% of mask-wearing mares, compared with only 21% of controls, with no statistically significant difference between the two treatment groups. These findings demonstrate that directional blue light therapy offers a practical, economical alternative to intensive housing systems, allowing mares to remain outdoors whilst achieving comparable reproductive advancement; this has substantial implications for breeding operations seeking to reduce overhead costs and improve animal welfare simultaneously, though practitioners should note that mask compliance and consistent daily use remain critical factors for success.
Read the full abstract on PubMed
Practical Takeaways
- •Light masks offer a cost-effective and welfare-friendly alternative to housing mares indoors under lights during the breeding season
- •Blue light masks can be used on mares maintained outdoors, reducing facility infrastructure costs while achieving comparable breeding season advancement (80% vs 87.5% cycling rates)
- •This technology allows breeders to maintain mares on pasture while still achieving reliable reproductive activation during off-season periods
Key Findings
- •Blue light masks applied to a single eye advanced breeding season in 80% of mares (20/25) compared to 21% in control group (4/19)
- •Light mask efficacy (80% cycling) was not significantly different from indoor barn lighting (87.5% cycling) for advancing estrous cyclicity
- •Low-intensity blue light directed at a single eye is an effective alternative to indoor housing for advancing the breeding season in mares