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Reproduction, fertility, and development2006; 18(6); 609-617; doi: 10.1071/rd06016

Obesity is associated with altered metabolic and reproductive activity in the mare: effects of metformin on insulin sensitivity and reproductive cyclicity.

Abstract: In mares, obesity is associated with continuous reproductive activity during the non-breeding season. To investigate the effect of obesity and associated alterations in metabolic parameters on the oestrous cycle, two related studies were conducted. In Experiment 1, obese (body condition score > 7) mares were fed ad libitum or were moderately feed restricted during the late summer and autumn months. Feed restriction did not alter the proportion of mares entering seasonal anoestrus. However, obese mares exhibited a significantly longer duration of the oestrous cycle, significant increases in circulating concentrations of leptin and insulin, and decreased insulin sensitivity and concentrations of thyroxine compared with feed-restricted mares throughout the experiment. Experiment 2 was designed to investigate the effects of administration of the insulin-sensitising drug metformin hydrochloride on insulin sensitivity and the characteristics of the oestrous cycle in obese mares. In a dose-response trial, metformin increased insulin sensitivity after 30 days following administration of 3 g day(-1), but not 6 or 9 g day(-1), compared with controls receiving vehicle only. However, there were no differences in insulin sensitivity or oestrous cycle characteristics between control and metformin-treated groups when the 3 g day(-1) dose was tested for a longer period of 2 months. These results demonstrate that obesity is associated with aberrations in the oestrous cycle and perturbations in several markers of metabolic status. The results also indicate that metformin is not an effective long-term monotherapy for increasing insulin sensitivity in horses at the doses tested. Additional studies are needed to examine possible effects of increasing insulin sensitivity on reproductive activity in obese mares.
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Publication Date: 2006-08-26 PubMed ID: 16930507DOI: 10.1071/rd06016Google Scholar: Lookup
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  • Journal Article
  • Research Support
  • Non-U.S. Gov't

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 research article discusses two studies that explore the impact of obesity on the reproductive activity and metabolism in mares, and the effectiveness of metformin, an insulin-sensitising drug, in addressing these issues. It was found that while metformin can initially increase insulin sensitivity, it did not prove to be an effective long-term treatment.

Two-Study Research on Obesity and Metformin Use in Mares

This paper primarily focuses on understanding the effect of obesity on the reproductive and metabolic process in mares, and how metformin, a generally used insulin-sensitising drug, can be used to counter some of the obesogenic effects. It explains the results of two closely related experimental studies on obese mares carried out to understand these aspects.

  • Experiment 1: The researchers studied the effect of uncontrolled feeding versus controlled feeding on obese mares during the late summer and autumn months. The aim was to learn how it influenced the oestrous cycle.
  • Experiment 2: The team evaluated how metformin impacted insulin sensitivity and the oestrous cycle in obese mares.

Findings and Implications

Several key findings were derived from these studies, which further elucidate the relationship between obesity, metabolism, and reproduction in mares.

  • In the first study, it was observed that feed restriction did not alter the tendency of mares to enter a state of quiescence in reproductive activity, termed as ‘seasonal anoestrus’.
  • However, obese mares displayed a longer duration of the oestrous cycle compared to those with feed restrictions.
  • In terms of metabolic changes, obese mares had significant increases in circulating concentrations of leptin and insulin and decreased insulin sensitivity.
  • Interestingly, in the second study, metformin appeared to boost insulin sensitivity in the short term. However, over a more extended period (two months), it failed to exhibit significant improvements in insulin sensitivity or oestrous cycle traits.

The article concludes by stressing that obesity does affect the oestrous cycle and metabolism of mares. However, metformin does not seem to be an effective long-term solution at the doses tested. Further research is needed to explore the implications of improved insulin sensitivity on the reproductive behaviour of obese mares.

Cite This Article

APA
Vick MM, Sessions DR, Murphy BA, Kennedy EL, Reedy SE, Fitzgerald BP. (2006). Obesity is associated with altered metabolic and reproductive activity in the mare: effects of metformin on insulin sensitivity and reproductive cyclicity. Reprod Fertil Dev, 18(6), 609-617. https://doi.org/10.1071/rd06016

Publication

Reproduction, fertility, and development
ISSN: 1031-3613
NlmUniqueID: 8907465
Country: Australia
Language: English
Volume: 18
Issue: 6
Pages: 609-617

Researcher Affiliations

Vick, M M
  • Department of Veterinary Science, Maxwell Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546, USA.
Sessions, D R
    Murphy, B A
      Kennedy, E L
        Reedy, S E
          Fitzgerald, B P

            MeSH Terms

            • Animals
            • Breeding
            • Dose-Response Relationship, Drug
            • Estrous Cycle
            • Female
            • Food Deprivation
            • Horse Diseases / drug therapy
            • Horse Diseases / physiopathology
            • Horses
            • Hypoglycemic Agents / administration & dosage
            • Insulin / blood
            • Insulin Resistance
            • Leptin / blood
            • Metformin / administration & dosage
            • Obesity / complications
            • Obesity / physiopathology
            • Obesity / veterinary
            • Reproduction
            • Seasons
            • Thyroxine / blood

            Citations

            This article has been cited 24 times.
            1. Pérez-Marín CC, Quintela LA. Current Insights in the Repeat Breeder Cow Syndrome. Animals (Basel) 2023 Jul 3;13(13).
              doi: 10.3390/ani13132187pubmed: 37443985google scholar: lookup
            2. 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.
              doi: 10.3389/fvets.2023.1180622pubmed: 37152686google scholar: lookup
            3. Pratt-Phillips S, Munjizun A. Impacts of Adiposity on Exercise Performance in Horses. Animals (Basel) 2023 Feb 14;13(4).
              doi: 10.3390/ani13040666pubmed: 36830453google scholar: lookup
            4. Fang X, Qin L, Yu H, Jiang P, Xia L, Gao Z, Yang R, Zhao Y, Yu X, Zhao Z. Comprehensive Analysis of miRNAs and Target mRNAs between Immature and Mature Testis Tissue in Chinese Red Steppes Cattle. Animals (Basel) 2021 Oct 21;11(11).
              doi: 10.3390/ani11113024pubmed: 34827757google scholar: lookup
            5. Benammar A, Derisoud E, Vialard F, Palmer E, Ayoubi JM, Poulain M, Chavatte-Palmer P. The Mare: A Pertinent Model for Human Assisted Reproductive Technologies?. Animals (Basel) 2021 Aug 4;11(8).
              doi: 10.3390/ani11082304pubmed: 34438761google scholar: lookup
            6. Ericsson AC, Johnson PJ, Gieche LM, Zobrist C, Bucy K, Townsend KS, Martin LM, LaCarrubba AM. The Influence of Diet Change and Oral Metformin on Blood Glucose Regulation and the Fecal Microbiota of Healthy Horses. Animals (Basel) 2021 Apr 1;11(4).
              doi: 10.3390/ani11040976pubmed: 33915682google scholar: lookup
            7. D'Fonseca NMM, Gibson CME, Hummel I, van Doorn DA, Roelfsema E, Stout TAE, van den Broek J, de Ruijter-Villani M. Overfeeding Extends the Period of Annual Cyclicity but Increases the Risk of Early Embryonic Death in Shetland Pony Mares. Animals (Basel) 2021 Feb 1;11(2).
              doi: 10.3390/ani11020361pubmed: 33535548google scholar: lookup
            8. Chusyd DE, Nagy TR, Golzarri-Arroyo L, Dickinson SL, Speakman JR, Hambly C, Johnson MS, Allison DB, Brown JL. Adiposity, reproductive and metabolic health, and activity levels in zoo Asian elephant (Elephas maximus). J Exp Biol 2021 Jan 26;224(Pt 2).
              doi: 10.1242/jeb.219543pubmed: 33500325google scholar: lookup
            9. Antwis RE, Edwards KL, Unwin B, Walker SL, Shultz S. Rare gut microbiota associated with breeding success, hormone metabolites and ovarian cycle phase in the critically endangered eastern black rhino. Microbiome 2019 Feb 15;7(1):27.
              doi: 10.1186/s40168-019-0639-0pubmed: 30770764google scholar: lookup
            10. Durward-Akhurst SA, Schultz NE, Norton EM, Rendahl AK, Besselink H, Behnisch PA, Brouwer A, Geor RJ, Mickelson JR, McCue ME. Associations between endocrine disrupting chemicals and equine metabolic syndrome phenotypes. Chemosphere 2019 Mar;218:652-661.
              doi: 10.1016/j.chemosphere.2018.11.136pubmed: 30502704google scholar: lookup
            11. Chusyd DE, Brown JL, Hambly C, Johnson MS, Morfeld K, Patki A, Speakman JR, Allison DB, Nagy TR. Adiposity and Reproductive Cycling Status in Zoo African Elephants. Obesity (Silver Spring) 2018 Jan;26(1):103-110.
              doi: 10.1002/oby.22046pubmed: 29265776google scholar: lookup
            12. Morfeld KA, Brown JL. Metabolic health assessment of zoo elephants: Management factors predicting leptin levels and the glucose-to-insulin ratio and their associations with health parameters. PLoS One 2017;12(11):e0188701.
              doi: 10.1371/journal.pone.0188701pubmed: 29186207google scholar: lookup
            13. de Laat MA, Hampson BA, Sillence MN, Pollitt CC. Sustained, Low-Intensity Exercise Achieved by a Dynamic Feeding System Decreases Body Fat in Ponies. J Vet Intern Med 2016 Sep;30(5):1732-1738.
              doi: 10.1111/jvim.14577pubmed: 27639952google scholar: lookup
            14. Shepherd ML, Ponder MA, Burk AO, Milton SC, Swecker WS Jr. Fibre digestibility, abundance of faecal bacteria and plasma acetate concentrations in overweight adult mares. J Nutr Sci 2014;3:e10.
              doi: 10.1017/jns.2014.8pubmed: 25191602google scholar: lookup
            15. Peugnet P, Wimel L, Duchamp G, Sandersen C, Camous S, Guillaume D, Dahirel M, Dubois C, Jouneau L, Reigner F, Berthelot V, Chaffaux S, Tarrade A, Serteyn D, Chavatte-Palmer P. Enhanced or reduced fetal growth induced by embryo transfer into smaller or larger breeds alters post-natal growth and metabolism in pre-weaning horses. PLoS One 2014;9(7):e102044.
              doi: 10.1371/journal.pone.0102044pubmed: 25006665google scholar: lookup
            16. Lacombe VA. Expression and regulation of facilitative glucose transporters in equine insulin-sensitive tissue: from physiology to pathology. ISRN Vet Sci 2014;2014:409547.
              doi: 10.1155/2014/409547pubmed: 24977043google scholar: lookup
            17. Ertelt A, Barton AK, Schmitz RR, Gehlen H. Metabolic syndrome: is equine disease comparable to what we know in humans?. Endocr Connect 2014 Sep;3(3):R81-93.
              doi: 10.1530/EC-14-0038pubmed: 24894908google scholar: lookup
            18. Morfeld KA, Lehnhardt J, Alligood C, Bolling J, Brown JL. Development of a body condition scoring index for female African elephants validated by ultrasound measurements of subcutaneous fat. PLoS One 2014;9(4):e93802.
              doi: 10.1371/journal.pone.0093802pubmed: 24718304google scholar: lookup
            19. Bauer SA, Arndt TP, Leslie KE, Pearl DL, Turner PV. Obesity in rhesus and cynomolgus macaques: a comparative review of the condition and its implications for research. Comp Med 2011 Dec;61(6):514-26.
              pubmed: 22330579
            20. Garland A, van Doorn DA, van den Boom R, Roelfsema E, Jung L, Boast M, Papadakis K, Margiotta M, Wafelbakker S, Briggs M, McCrae P, Pearson W. Morphometric changes in overweight horses following 10-week weight loss programs. BMC Vet Res 2025 Oct 10;21(1):596.
              doi: 10.1186/s12917-025-05032-zpubmed: 41068901google scholar: lookup
            21. Zhou Q, Luo B, Yang B, Li D, Wei R, Xie C, Yu J, Meng X, Cheng J, He M, Yang L. Case Report: A case study on the relationship between obesity and estrus in female captive panda. Front Vet Sci 2025;12:1552754.
              doi: 10.3389/fvets.2025.1552754pubmed: 40343364google scholar: lookup
            22. Talbot AM, Shanks-Boon H, Baldwin CM, Barnes H, Maddox TW. Soft palate angle and basihyoid depth increase with tongue size and with body condition score in horses. Equine Vet J 2025 Jul;57(4):967-976.
              doi: 10.1111/evj.14445pubmed: 39748477google scholar: lookup
            23. Michanek P, Bröjer J, Lilliehöök I, Fjordbakk CT, Löwgren M, Hedeland M, Bergquist J, Ekstrand C. Pharmacokinetics and Alterations in Glucose and Insulin Levels After a Single Dose of Canagliflozin in Healthy Icelandic Horses. J Vet Pharmacol Ther 2025 Jan;48 Suppl 1(Suppl 1):41-49.
              doi: 10.1111/jvp.13476pubmed: 39113254google scholar: lookup
            24. Catandi GD, Fresa KJ, Cheng MH, Whitcomb LA, Broeckling CD, Chen TW, Chicco AJ, Carnevale EM. Follicular metabolic alterations are associated with obesity in mares and can be mitigated by dietary supplementation. Sci Rep 2024 Mar 30;14(1):7571.
              doi: 10.1038/s41598-024-58323-0pubmed: 38555310google scholar: lookup
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