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Endocrine responses in mares undergoing abrupt changes in nutritional management
P R Buff1, B R Spader, C D Morrison
1Division of Animal Sciences, University of Missouri, Columbia, Missouri 65211, USA.
Journal of Animal Science
|September 15, 2006
Summary
In obese pony mares, feed restriction rapidly decreased leptin levels, while insulin and growth hormone (GH) showed dynamic changes. Leptin recovery was slow after nutritional insult.
Area of Science:
- Animal Physiology
- Endocrinology
- Nutritional Science
Background:
- Leptin regulates energy homeostasis and body composition.
- Obese pony mares exhibit a rapid decline in leptin during acute feed restriction.
- Understanding temporal hormone changes during nutritional transitions is crucial.
Purpose of the Study:
- To characterize temporal changes in leptin, growth hormone (GH), and insulin concentrations.
- To investigate hormonal responses in obese pony mares during feed restriction and refeeding cycles.
Main Methods:
- Nine obese pony mares were assigned to two treatment groups (RFR and FRF).
- Hormone concentrations were measured via blood sampling during defined periods of feed restriction and refeeding.
- Statistical analysis identified significant changes in hormone levels based on treatment and time.
Main Results:
- Plasma leptin concentrations decreased significantly within 6 hours of feed removal and remained low, showing a slow recovery.
- Feed restriction led to decreased plasma insulin and increased GH (mean concentration, pulse frequency, amplitude, and AUC).
- Refeeding reversed the effects of feed restriction on insulin and GH levels.
Conclusions:
- Peripheral insulin and GH concentrations are dynamically responsive to feed availability and removal in obese pony mares.
- Leptin decreases with feed restriction but exhibits a delayed recovery, indicating sensitivity to transient nutritional insults.
- These findings highlight differential hormonal regulation in response to nutritional status changes in equine models.
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