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Reproductive biology and endocrinology : RB&E2011; 9; 130; doi: 10.1186/1477-7827-9-130

Effects of nutritional cues on the duration of the winter anovulatory phase and on associated hormone levels in adult female Welsh pony horses (Equus caballus).

Abstract: Mares have an annual reproductive rhythm, with a phase of inactivity in midwinter. The aim of this study was to determine the impact of food restriction on physiological and metabolic hallmarks of this rhythm. Methods: Over three successive years, 3 groups of 10 mares were kept under natural photoperiod. A 'well-fed' group was fed to maintain the mares in good body condition; a 'restricted' group received a diet calculated to keep the mares thin and a 'variable' group was fed during some periods like the 'restricted' group and during some other periods like the 'well-fed' group, with the aim of mimicking the natural seasonal variation of pasture availability, but a few months in advance of this natural rhythm. Results: Winter ovarian inactivity always occurred and was long in the restricted group. In contrast, in the 'well-fed' group, 40% of mares showed this inactivity, which was shorter than in the other groups. Re-feeding the 'variable' group in autumn and winter did not advance the first ovulation in spring, compared with the 'restricted' group. Measurements of glucose and insulin concentrations in mares from the 'restricted' group during two 24 h periods of blood sampling, revealed no post-prandial peaks. For GH (Growth hormone), IGF-1 and leptin levels, large differences were found between the 'well-fed' group and the other groups. The glucose, insulin, GH and leptin levels but not melatonin level are highly correlated with the duration of ovulatory activity. Conclusions: The annual rhythm driven by melatonin secretion is only responsible for the timing of the breeding season. The occurrence and length of winter ovarian inactivity is defined by metabolic hormones.
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Publication Date: 2011-09-29 PubMed ID: 21958120PubMed Central: PMC3195710DOI: 10.1186/1477-7827-9-130Google Scholar: Lookup
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  • Comparative Study
  • Journal Article
  • Randomized Controlled Trial
  • 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 investigates the impact of various dietary restrictions on the winter anovulatory phase and hormone levels in adult female Welsh pony horses. The authors found that feeding restrictions contributed to a more substantial winter ovarian inactivity period and influenced specific metabolic hormone levels.

Objective & Research Methodology

  • The researchers aimed to explore how food restrictions impacted the annual reproductive rhythms in adult female Welsh pony horses, specifically looking at the physiological and metabolic indicators.
  • The experiment was carried out over three years using three groups of 10 mares each under natural photoperiod conditions. These were:
    • A ‘well-fed’ group, where horses were given sufficient food to maintain good bodily conditions.
    • A ‘restricted’ group, which was supplied with limited food to induce thinness.
    • A ‘variable’ group, whose diet varied between restriction and abundance to mimic natural seasonal variations in food availability, slightly ahead of natural rhythm.

Results and Findings

  • Ovarian inactivity during winter was consistent across all groups but was extensive in the ‘restricted’ group.
  • In the ‘well-fed’ group, only 40% of the mares exhibited this inactivity, and it was considerably short compared to other groups.
  • Re-feeding the ‘variable’ group during autumn and winter did not hasten the first ovulation in spring, compared to the ‘restricted’ group.
  • No significant post-prandial (after meals) peak in glucose and insulin levels was observed in mares from the ‘restricted’ group during two 24-hour blood sampling periods.
  • There were notable differences in glucose, insulin, Growth hormone (GH), and leptin levels between the ‘well-fed’ group and the other groups.
  • The researchers discovered a strong correlation between glucose, insulin, GH, leptin levels but not with melatonin level and the duration of ovulatory activity.

Conclusion

  • The study concluded that while the annual rhythm directed by melatonin secretion regulates the timing of the breeding season, the occurrence and duration of winter ovarian inactivity is determined by metabolic hormones.

Cite This Article

APA
Salazar-Ortiz J, Camous S, Briant C, Lardic L, Chesneau D, Guillaume D. (2011). Effects of nutritional cues on the duration of the winter anovulatory phase and on associated hormone levels in adult female Welsh pony horses (Equus caballus). Reprod Biol Endocrinol, 9, 130. https://doi.org/10.1186/1477-7827-9-130

Publication

Reproductive biology and endocrinology : RB&E
ISSN: 1477-7827
NlmUniqueID: 101153627
Country: England
Language: English
Volume: 9
Pages: 130

Researcher Affiliations

Salazar-Ortiz, Juan
  • INRA, UMR85 Physiologie de la Reproduction et des Comportements, Nouzilly, France.
Camous, Sylvaine
    Briant, Christine
      Lardic, Lionel
        Chesneau, Didier
          Guillaume, Daniel

            MeSH Terms

            • Adiposity
            • Animals
            • Anovulation / blood
            • Anovulation / pathology
            • Anovulation / physiopathology
            • Anovulation / veterinary
            • Blood Glucose / analysis
            • Body Weight
            • Caloric Restriction / veterinary
            • Circadian Rhythm / radiation effects
            • Female
            • France
            • Growth Hormone / blood
            • Horses / physiology
            • Insulin / blood
            • Insulin-Like Growth Factor I / analysis
            • Leptin / blood
            • Melatonin / blood
            • Ovulation / radiation effects
            • Photoperiod
            • Seasons
            • Subcutaneous Fat, Abdominal / pathology
            • Time Factors

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