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PloS one2020; 15(1); e0227115; doi: 10.1371/journal.pone.0227115

The effects of extended photoperiod and warmth on hair growth in ponies and horses at different times of year.

Abstract: Photoperiod is considered the most dominant environmental cue allowing animals to anticipate and adapt to seasonal changes. In seasonally breeding mammals, changes in daylength alter pineal melatonin secretion and pituitary prolactin secretion. During the seasonal transition to shorter winter daylengths, increased production of melatonin and declining prolactin are associated with triggering winter coat growth in many animals. Similarly, studies have shown that artificial extension of photoperiod suppresses melatonin secretion and lifts prolactin inhibition to activate moulting. Four longitudinal cohort studies were conducted to determine if extended photoperiod and warmth, provided by mobile light masks and rugs (horse blankets), could reverse the onset of winter coat growth, maintain the summer coat and accelerate winter coat shedding in horses and in ponies. Studies began at dates corresponding to the autumnal equinox, one month post-summer solstice, one month pre-winter solstice and one month post-winter solstice, respectively. To extend photoperiod to approximately 15h of light, commercially available head-worn light masks provided low intensity blue light to one eye until 11pm daily. Coat condition and shedding rate were scored and hair samples collected, measured and weighed bi-weekly. Data from control and treatment groups were analysed by repeated measures ANOVA. Results revealed that extended photoperiod 1) did not reverse winter coat growth when initiated at the autumnal equinox, 2) effectively maintained the summer coat in stabled horses when initiated one month post-summer solstice, 3) accelerated shedding in outdoor living horses when initiated one month pre-winter solstice and 4) did not accelerate shedding in indoor or outdoor living ponies when initiated one month post-winter solstice. To successfully manage equine coat growth while also preserving optimal thermoregulation in both competition and breeding stock correct timing of light application is crucial and requires careful monitoring of environmental temperature. Further studies are needed where variations in breed and management are considered.
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Publication Date: 2020-01-14 PubMed ID: 31935219PubMed Central: PMC6959597DOI: 10.1371/journal.pone.0227115Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The study examines the effects of extended light periods and warmth on the coat growth and shedding of horses and ponies, using head-worn light masks and horse blankets. The results vary based on the timing of the extended photoperiod, showing it can help maintain summer coats, accelerate shedding, but does not always significantly affect winter coat growth.

Research Context and Method

  • Photoperiod, or daylength, is a major environmental cue animals use to adapt to seasonal changes. Changes in photoperiod affect the secretion of certain hormones such as melatonin and prolactin, which in turn influence the growth and shedding of winter coats in many animals.
  • The research aimed to investigate how manipulating these light levels could affect coat growth and shedding in horses and ponies, with potential implications for managing equine coat growth.
  • The researchers conducted four longitudinal studies, starting at different times of year – at the autumn equinox, one month after the summer solstice, one month before the winter solstice, and one month after the winter solstice.
  • They extended the light (photoperiod) available to their subjects to about 15 hours per day using head-worn light masks. They also used horse blankets for warmth.
  • Coat condition and shedding rate were monitored closely. Hair samples were collected, measured, and weighed bi-weekly, and the data from control and treatment groups analyzed statistically.

Results and Conclusion

  • The results revealed different outcomes depending on the timing of lighting manipulation. Extended photoperiod did not reverse winter coat growth when initiated at the autumn equinox.
  • It was, however, effective in maintaining the summer coat in sheltered horses when initiated one month post-summer solstice.
  • Interestingly, it accelerated shedding in horses living outdoors when initiated one month before the winter solstice.
  • But it did not affect shedding in ponies (whether indoors or outdoors) when initiated one month post-winter solstice.
  • The study concludes that managing equine coat growth involves careful timing of light application, and monitoring of environmental temperature is essential to maintain optimal thermoregulation. There is a need for further studies considering factors such as breed variation and management.

Cite This Article

APA
O'Brien C, Darcy-Dunne MR, Murphy BA. (2020). The effects of extended photoperiod and warmth on hair growth in ponies and horses at different times of year. PLoS One, 15(1), e0227115. https://doi.org/10.1371/journal.pone.0227115

Publication

PloS one
ISSN: 1932-6203
NlmUniqueID: 101285081
Country: United States
Language: English
Volume: 15
Issue: 1
Pages: e0227115
PII: e0227115

Researcher Affiliations

O'Brien, Christiane
  • Equilume Ltd., Naas, Co. Kildare, Ireland.
Darcy-Dunne, Megan Ruth
  • School of Agriculture and Food Science, University College Dublin, Belfield, Dublin, Ireland.
Murphy, Barbara Anne
  • School of Agriculture and Food Science, University College Dublin, Belfield, Dublin, Ireland.

MeSH Terms

  • Animal Fur / growth & development
  • Animal Fur / physiology
  • Animals
  • Horses / physiology
  • Photoperiod
  • Seasons
  • Temperature

Conflict of Interest Statement

I have read the journal's policy and the authors of this manuscript have the following competing interests: BAM is the Founder of Equilume Ltd., a spin-out company deriving from her research program as assistant professor at UCD and is a member of the company’s Board of Directors. BAM is a shareholder in Equilume Ltd. COB is and employee of Equilume Ltd in the role of Research Manager. The light mask used in the presented studies is a commercially available product with the following patents: AU2012101968 GB2504244 GB2549682 US9,839,791 This does not alter our adherence to PLOS ONE policies on sharing data and materials.

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