Blue light from individual light masks directed at a single eye advances the breeding season in mares

Abstract

Low-intensity blue light to a single eye from a light mask is an effective alternative to maintenance of mares indoors under lights for advancing the breeding season. Mobile light therapy for horses could have economic benefits for the breeder by reducing the costs of maintaining mares indoors, and welfare benefits for horses by permitting outdoor maintenance.

Effect of environmental factors and changes in the body condition score on the onset of the breeding season in mares

“…It was suggested that changes in body composition may occur as a result of strengthened circadian rhythmicity of peripheral clocks and better internal synchronization that were the result of the abundance of (blue) light during daytime (Murphy & O'Brien, ). Moreover, in recent years, it has been demonstrated that blue light is the essential signal for entrainment of circadian rhythm in mares (Murphy et al, ; Nolan et al, ; Walsh et al, , ). Manipulation of the photoperiod using artificial blue light results in an earlier onset of cyclicity in the spring, reduced duration of pregnancy, increased birthweight of foals and changes in hair coat at birth (Murphy et al, ; Nolan et al, ).…”

“…Moreover, in recent years, it has been demonstrated that blue light is the essential signal for entrainment of circadian rhythm in mares (Murphy et al, ; Nolan et al, ; Walsh et al, , ). Manipulation of the photoperiod using artificial blue light results in an earlier onset of cyclicity in the spring, reduced duration of pregnancy, increased birthweight of foals and changes in hair coat at birth (Murphy et al, ; Nolan et al, ). The spectral qualities of different light sources (incandescent light, fluorescent light and direct natural sunlight) are significantly different from each other with natural daylight having the highest proportion of biologically effective short wavelength blue light (Murphy, ).…”

“…Several treatment regimens have been implemented in an effort to advance the onset of the breeding season. Most of these treatments have focused on increasing the photoperiod (number of hours of light per day), and it has been repeatedly demonstrated that an artificial, long photoperiod effectively advances the time of the first ovulation in mares (Daels, 2006;Kooistra & Ginther, 1975;Malinowski, Johnson, & Scanes, 1985;Murphy et al, 2014;Oxender, Noden, & Hafs, 1977;Palmer, Driancourt, & Ortavant, 1982). To a lesser extent, various schemes of administering gonadotropins, dopamine antagonist and/or progesterone, have also been shown to stimulate an early onset of reproductive activity (return to cyclicity) during the deep anestrous season or the transitional period (Alexander & Irvine, 1991;Besognet, Hansen, & Daels, 1996;Donadeu & Thompson, 2002;Evans & Irvine, 1979;Harrison, Squires, Nett, & McKinnon, 1990;Hyland et al, 1987;McCue, Logan, & Magee, 2007;McKinnon, Vasey, Lescun, & Trigg, 1997;Panzani et al, 2011;Squires, Heesemann, Webel, Shideler, & Voss, 1983;Turner & Irvine, 1991).…”

Half a century of equine reproduction research and application: A veterinarytour de force

“…Getting so many of the maiden and barren mares covered early in the season eases the pressure on the foaling mares, stud staff and stallions alike so therefore has a significant influence on overall breeding efficiency. And most recently, the advent of the blue light masks (Fig ) has also been shown to hasten early season oestrous cyclicity in barren and maiden mares .…”

Progress in broodmare practice as based on recent papers in Equine Veterinary Journal

“…Blue light advances the breeding season in mares [8] Horses are 'long day breeders'. Due to the northern hemisphere stud book authorities specifying a birthday on 1 January for all Thoroughbred racehorses, breeders and veterinarians have utilised artificial light to inhibit endogenous melatonin secretion.…”