Artificially extended photoperiod administered to pre-partum mares via blue light to a single eye: Observations on gestation length, foal birth weight and foal hair coat at birth.
Abstract: In seasonally breeding animals, photoperiod perception is crucial for timing of important physiological events. In the horse, long day photoperiod influences the onset of ovulation and cyclicity, shedding of the heavier winter coat and the timing of parturition. In this compilation of studies, conducted across three breeding seasons and two countries, the impact of artificially extended day length was investigated on gestation length, foal birth weight and foal hair coat at birth. The light therapy was administered to pre-partum mares via mobile head worn masks which provided short wavelength blue light to a single eye. In Study 1, reductions in gestation lengths were observed following administration of artificially extended day length (124.8 ± 15.11 days) in the final months of pregnancy to a group of Thoroughbred mares compared to controls (P < 0.05; 339.7 ± 9.56 days vs 350.6 ± 9.13). Study 2 revealed that pre-partum exposure to artificially extended day length (104.6 ± 9.89 days) increased foal birth weight compared to controls (47.13 ± 2.93 kg vs 43.51 ± 6.14 kg; P < 0.05) in mares bred early in the year. In Study 3, artificially extended day length (87.53 ± 19.6 days) administered to pre-partum mares affected the coat condition of foals at birth with respect to hair weight (P < 0.0001) and hair length (P < 0.0001) compared to controls (0.34 ± 0.20 μg vs 0.59 ± 0.12 μg and 1.93 ± 0.56 cm vs 2.56 ± 0.32 cm, respectively). Collectively, these studies serve to highlight the influential role of the circa-annual changes in photoperiod length on the pre-partum mare for normal foetal development during the natural breeding season. It also emphasizes the potential that exists to improve breeding efficiency parameters by artificially simulating this important environmental cue in the latter stages of gestation against the backdrop of an economically driven early breeding season.
Copyright © 2017 Elsevier Inc. All rights reserved.
Publication Date: 2017-06-09 PubMed ID: 28708527DOI: 10.1016/j.theriogenology.2017.06.012Google Scholar: Lookup
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Summary
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The research investigates the effects of artificially extending the day length on pre-partum mares during the final months of pregnancy. Results indicate that this practice can influence the gestation period, foal birth weight, and the foal’s hair coat at birth.
Objective of the Research
- The research aimed to explore the impact of artificially extended day length, delivered via blue light to one eye, on gestation length, foal birth weight, and the condition of the foal’s hair coat at birth.
- This was investigated across different geographical settings and over three breeding seasons.
Method of Research
- The scientists used mobile head-worn masks to deliver short wavelength blue light to one eye of pre-partum mares.
- Three studies were conducted to examine the effects of artificially extending day length on varying factors of the foals’ birth and early development.
Findings of the Research
- Study 1 revealed that mares exposed to artificially extended day length had shorter gestation periods compared to control groups.
- In Study 2, it was discovered that foals born to mares exposed to extended day length early in the year had higher birth weights than those in control groups.
- Study 3 demonstrated that artificially extended day length affected the foal’s coat condition at birth, specifically in terms of hair weight and length.
Implications of the Research
- The slight manipulation of photoperiod perception greatly influenced the pre-partum mares’ gestation, influencing both the length of pregnancy and the physical attributes of the foals.
- This suggests a strong tie between environmental cues and physiological processes in seasonally breeding animals, like horses.
- The study also offers potential strategies to improve breeding efficiency, particularly during economically-driven early breeding seasons.
Cite This Article
APA
Nolan MB, Walsh CM, Duff N, McCrarren C, Prendergast RL, Murphy BA.
(2017).
Artificially extended photoperiod administered to pre-partum mares via blue light to a single eye: Observations on gestation length, foal birth weight and foal hair coat at birth.
Theriogenology, 100, 126-133.
https://doi.org/10.1016/j.theriogenology.2017.06.012 Publication
Researcher Affiliations
- School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland. Electronic address: margaret.nolan@up.ac.za.
- School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland. Electronic address: cwalsh@winstarfarm.com.
- School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland.
- School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland.
- School of Electrical, Electronic and Mechanical Engineering, University College Dublin, Belfield, Dublin 4, Ireland.
- School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland. Electronic address: barbara.murphy@ucd.ie.
MeSH Terms
- Animals
- Animals, Newborn
- Birth Weight / radiation effects
- Female
- Hair
- Horses / physiology
- Light
- Photoperiod
- Pregnancy
- Pregnancy, Animal / radiation effects
Citations
This article has been cited 10 times.- Akhtar MF, Swelum AA, Wang C. Effect of Monochromatic Red, Blue, and White Light on Reproductive Hormones of Male Donkeys During the Non-Breeding Season. Animals (Basel) 2026 Feb 4;16(3).
- Parmantier S, Kyriazopoulou P, McClendon M, Adams A, Murphy BA. Influence of Extended Photoperiod Using Blue Light Masks on Hypertrichosis, Coat Condition and General Health Parameters in Horses with Pituitary Pars Intermedia Dysfunction. Animals (Basel) 2025 Oct 5;15(19).
- Ishimaru M, Kume K, Murase H, Sato F, Matsui A, Ohmura H, Taya K. Effect of birth month on endocrine function in Thoroughbred foals born in Hokkaido, the northern part of Japan. J Vet Med Sci 2025 Jul 7;87(7):804-815.
- Zhang Y, Zhao X, Li S, Bai S, Zhang W. The Retinoic-Acid-Related Orphan Receptor Alpha May Be Highly Involved in the Regulation of Seasonal Hair Molting. Int J Mol Sci 2025 Feb 13;26(4).
- Yu Z, Dong Y, Chen Y, Aleya L, Zhao Y, Yao L, Gu W. It is time to explore the impact of length of gestation and fetal health on the human lifespan. Aging Cell 2024 Apr;23(4):e14157.
- Farag HI, Murphy BA, Templeman JR, Hanlon C, Joshua J, Koch TG, Niel L, Shoveller AK, Bedecarrats GY, Ellison A, Wilcockson D, Martino TA. One Health: Circadian Medicine Benefits Both Non-human Animals and Humans Alike. J Biol Rhythms 2024 Jun;39(3):237-269.
- Gáspárdy A, Gallagher G, Bartha B, Haaland H, Fekete SG. The Effect of Supplemental Lighting during the Late Gestation Period on Post-Partum Mechanical Properties of Mare and Foal Guard Hair. Vet Sci 2024 Jan 22;11(1).
- McLoda S, Anderson NC, Earing J, Lugar D. Effect of Light Regiment on Farrowing Performance and Behavior in Sows. Animals (Basel) 2021 Sep 30;11(10).
- Todd ET, Hamilton NA, Velie BD, Thomson PC. The effects of inbreeding on covering success, gestation length and foal sex ratio in Australian thoroughbred horses. BMC Genet 2020 Apr 8;21(1):41.
- O'Brien C, Darcy-Dunne MR, Murphy BA. The effects of extended photoperiod and warmth on hair growth in ponies and horses at different times of year. PLoS One 2020;15(1):e0227115.
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