High interindividual and intraindividual variation of oxytocin secretion in estrous mares exposed to stallions, but no significant link to mate preferences.
Abstract: Oxytocin is a hormone that may not only influence reproductive mechanisms in mammals but also their social behavior, including pair bonding. We therefore tested if the concentrations of oxytocin and other hormones reveal mate preferences of 13 mares in estrus. Each mare was first exposed to two stallions (haphazardly selected out of seven) and her behavior recorded. The mare was then returned to her box (i.e., no contact to stallions during that time). Approximately 4.5 hours later, venous blood samples were collected every minute during 30 minutes preceding exposure to one of the two previously used stallions, 6 minutes during exposure, and 30 minutes after exposure back in the mare's box. The procedure was repeated in the consecutive estrus cycle, with the difference that the mare was each exposed to the other of the two stallions during oxytocin measurements. In 20 of the 26 trials, oxytocin concentrations were significantly elevated during exposure to the stallion, without significant associations to cortisol and estradiol concentrations. We found no significant association between oxytocin secretion and preferences in the previous choice situation. While estradiol concentration showed a high repeatability over the two cycles, we found considerable intraindividual differences in oxytocin and cortisol plasma concentration among the two cycles. Partially, the variation in oxytocin concentrations could be linked to the time of ovulation, with lower oxytocin plasma concentrations in mares which ovulated later than expected. In conclusion, when teasing under experimental conditions, we found high interindividual and intraindividual variation among mares in the increase of oxytocin plasma concentrations, depending on the timing of ovulation. However, oxytocin levels seemed to be no predictor of mare preference.
Copyright © 2016 Elsevier Inc. All rights reserved.
Publication Date: 2016-07-25 PubMed ID: 27587272DOI: 10.1016/j.theriogenology.2016.07.017Google Scholar: Lookup
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- Clinical Trial
- Journal Article
Summary
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This research explored the role of the hormone oxytocin in reproductive and social behavior in estrous mares, specifically their mate preference when exposed to stallions. The study, which examined 13 mares, found a significant increase in oxytocin levels during exposure to the stallion, but did not find a direct association between oxytocin levels and mare mate preference.
Study Procedure
- This study involved 13 mares who were each exposed to two randomly selected stallions. The researchers monitored the mares’ behavior during these encounters.
- Following an exposure period, the mares were returned to their boxes and deprived of stallion contact for 4.5 hours. Venous blood samples were taken frequently over a 30-minute period before the second stallion encounter, during the 6-minute encounter, and for a 30-minute period afterward back in the mare’s box.
- This procedure was repeated in the subsequent estrus cycle, but each mare was exposed to the alternate stallion during the oxytocin measurements.
Results & Findings
- In 20 of the 26 trials, a notable rise in oxytocin levels occurred during exposure to the stallion. However, no substantial relationships with cortisol and estradiol concentrations were observed.
- The study did not find a significant link between oxytocin levels and the mares’ preferences in the previous choice situation.
- While estradiol levels showed a high repeatability over the two cycles, oxytocin and cortisol plasma concentration varied significantly among the two cycles within individual mares.
- Partially, the variation in oxytocin concentrations correlated to the time of ovulation, with lower oxytocin plasma concentrations observed among the mares that ovulated later than expected.
Conclusions
- Through this study, under experimental teasing conditions, a high variation was found in the increase of oxytocin plasma concentrations among individual mares, arguably influenced by the timing of ovulation.
- However, despite higher oxytocin levels during the stallion exposure, it was concluded that it does not predict mare preference.
Cite This Article
APA
Käser R, Bruckmaier RM, Thomas S, Sieme H, Wedekind C, Burger D.
(2016).
High interindividual and intraindividual variation of oxytocin secretion in estrous mares exposed to stallions, but no significant link to mate preferences.
Theriogenology, 86(9), 2222-2229.
https://doi.org/10.1016/j.theriogenology.2016.07.017 Publication
Researcher Affiliations
- Swiss Institute of Equine Medicine, Agroscope and University of Berne, Avenches, Switzerland.
- Veterinary Physiology, Vetsuisse Faculty, University of Berne, Berne, Switzerland.
- Swiss Institute of Equine Medicine, Agroscope and University of Berne, Avenches, Switzerland; Department of Ecology and Evolution, Biophore, University of Lausanne, Lausanne, Switzerland.
- Clinic for Horses, Unit for Reproductive Medicine, University of Veterinary Medicine Hanover, Hanover, Germany.
- Department of Ecology and Evolution, Biophore, University of Lausanne, Lausanne, Switzerland.
- Swiss Institute of Equine Medicine, Agroscope and University of Berne, Avenches, Switzerland. Electronic address: dominik.burger@vetsuisse.unibe.ch.
MeSH Terms
- Animals
- Estradiol / blood
- Estrus / physiology
- Female
- Horses / blood
- Horses / physiology
- Hydrocortisone / blood
- Male
- Oxytocin / metabolism
- Sexual Behavior, Animal / physiology
Citations
This article has been cited 1 times.- Jeannerat E, Janett F, Sieme H, Wedekind C, Burger D. Quality of seminal fluids varies with type of stimulus at ejaculation. Sci Rep 2017 Mar 13;7:44339.
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