Effects of sex, pregnancy and season on insulin secretion and carbohydrate metabolism in horses.
Abstract: In pregnant mares, peripheral insulin antagonism channels glucose preferentially to the foetus. On the other hand, horses reduce their metabolic activity in winter. Taking these aspects of equine pregnancy and metabolism together, we hypothesized that glucose clearance from blood and the insulin response to glucose do not only change throughout gestation but also with season. To test this hypothesis, the glucose and insulin response to an oral glucose test and relative insulin release were analysed in pregnant mares (n=12) and in geldings (n=10) as controls. Animals were tested in June, September, December, and in March (geldings) and on day 320 of gestation (mares). Furthermore, the 6 mares foaling early and 6 foaling later in the year were compared. In mares and geldings, plasma glucose concentration increased after glucose feeding (p<0.001). The increase was more pronounced in mares (p<0.05) and increased from June to December in mares (p<0.001) but not geldings (month x group p<0.05). This indicates constant glucose clearance in geldings but reduced clearance in pregnant mares. A partial insulin resistance is thus induced by pregnancy independent from season. Insulin release increased after glucose feeding (p<0.001) similarly in geldings and mares. The insulin response to glucose and relative insuslin release increased from June to December (p<0.001) indicating seasonal changes in β-cell sensitivity. Glucose and insulin concentration did not differ between early and late foaling mares. In conclusion, in horses, β-cell sensitivity to glucose is affected by season while insulin sensitivity during pregnancy decreases independent from season.
Copyright © 2017 Elsevier B.V. All rights reserved.
Publication Date: 2017-07-06 PubMed ID: 28701287DOI: 10.1016/j.anireprosci.2017.07.002Google Scholar: Lookup
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- Journal Article
Summary
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This research investigates how pregnancy and season changes impact insulin secretion and glucose metabolism in horses, with study results highlighting specific variations between male (geldings) and pregnant female (mares) horses.
Objectives and Hypothesis
- The research aimed to examine the impacts of sex, pregnancy, and season on insulin secretion and carbohydrate metabolism in horses.
- Given the known effects of pregnancy and winter on horses – with pregnant mares reportedly showing increased glucose delivery to foetuses and horses generally reducing metabolic activity in winter – the researchers hypothesised that both the insulin response to glucose and glucose clearance from blood would vary not just during gestation, but also with the season.
Methodology
- A total of 12 pregnant mares and 10 geldings were involved in the study.
- The insulin response and glucose clearance were analysed in these subjects through oral glucose tests and checking relative insulin release.
- These assessments were made at four stages throughout the year – June, September, December, and March for geldings, and on the 320th day of gestation for the mares.
Findings
- Both mares and geldings exhibited an increase in plasma glucose concentration post-glucose feeding. This increase was however more significant in mares and rose from June to December but not in geldings.
- This finding suggests constant glucose clearance in geldings but a reduction in pregnant mares, implying that a certain level of insulin resistance is introduced by pregnancy regardless of season.
- The insulin response and relative insulin release following glucose feeding increased in a similar manner in both mares and geldings from June to December, indicating seasonal changes in β-cell sensitivity.
- Interestingly, there was no noticeable difference in glucose and insulin concentrations amongst mares based on foaling times (early or late in the year).
Conclusion
- Based on the research, the researchers concluded that although the insulin response during pregnancy decreases independent of the season, β-cell sensitivity towards glucose is noticeably impacted by seasonal changes.
Cite This Article
APA
Beythien E, Wulf M, Ille N, Aurich J, Aurich C.
(2017).
Effects of sex, pregnancy and season on insulin secretion and carbohydrate metabolism in horses.
Anim Reprod Sci, 184, 86-93.
https://doi.org/10.1016/j.anireprosci.2017.07.002 Publication
Researcher Affiliations
- Graf Lehndorff Institute for Equine Science, Vetmeduni Vienna, Neustadt (Dosse), Germany.
- Graf Lehndorff Institute for Equine Science, Vetmeduni Vienna, Neustadt (Dosse), Germany.
- Artificial Insemination and Embryo Transfer, Department for Small Animals and Horses, Vetmeduni Vienna, Vienna, Austria.
- Obstetrics and Reproduction, Department for Small Animals and Horses, Vetmeduni Vienna, Vienna, Austria.
- Artificial Insemination and Embryo Transfer, Department for Small Animals and Horses, Vetmeduni Vienna, Vienna, Austria. Electronic address: christine.aurich@vetmeduni.ac.at.
MeSH Terms
- Animal Feed / analysis
- Animal Nutritional Physiological Phenomena
- Animals
- Blood Glucose
- Carbohydrate Metabolism / physiology
- Diet / veterinary
- Female
- Glucose / administration & dosage
- Glucose Tolerance Test / veterinary
- Insulin / metabolism
- Insulin-Secreting Cells / physiology
- Male
- Pregnancy
- Pregnancy, Animal / physiology
- Seasons
- Time Factors
Citations
This article has been cited 7 times.- Hallman I, Karikoski N, Kareskoski M. The effects of obesity and insulin dysregulation on mare reproduction, pregnancy, and foal health: a review. Front Vet Sci 2023;10:1180622.
- Karikoski NP, Box JR, Mykkänen AK, Kotiranta VV, Raekallio MR. Variation in insulin response to oral sugar test in a cohort of horses throughout the year and evaluation of risk factors for insulin dysregulation. Equine Vet J 2022 Sep;54(5):905-913.
- Maśko M, Zdrojkowski Ł, Wierzbicka M, Domino M. Association between the Area of the Highest Flank Temperature and Concentrations of Reproductive Hormones during Pregnancy in Polish Konik Horses-A Preliminary Study. Animals (Basel) 2021 May 23;11(6).
- Hicks GR, Fraser NS, Bertin FR. Changes Associated with the Peri-Ovulatory Period, Age and Pregnancy in ACTH, Cortisol, Glucose and Insulin Concentrations in Mares. Animals (Basel) 2021 Mar 20;11(3).
- Carslake HB, Pinchbeck GL, McGowan CM. Equine metabolic syndrome in UK native ponies and cobs is highly prevalent with modifiable risk factors. Equine Vet J 2021 Sep;53(5):923-934.
- Lopes A, Huber L, Durham AE. The Seasonality of Serum Insulin Concentrations in Equids and the Association With Breed, Age, and Sex. J Vet Intern Med 2025 May-Jun;39(3):e70089.
- Viviani P, Lavado RA, Chavarria NH, Ragno VM, Montgomery JB. Spring and fall blood concentrations of adrenocorticotropic hormone, insulin, and thyroxine in healthy horses in Saskatchewan. Can Vet J 2024 Apr;65(4):335-342.
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