Endocrine responses in mares undergoing abrupt changes in nutritional management.
Abstract: Leptin, a protein hormone secreted by adipocytes, plays an important role in energy homeostasis and regulation of body composition. We previously observed that acute feed restriction resulted in a rapid decline in concentrations of leptin in obese pony mares. This acute response prompted us to characterize the temporal changes in concentrations of leptin, GH, and insulin in obese pony mares during the transition between fed and feed-restricted conditions. Nine obese pony mares of mixed breed, previously maintained on fescue pasture, were randomly allotted to 2 groups. Treatments consisted of a 48-h feed restriction, a 48-h refeeding, and a 24-h feed restriction (RFR; n = 4), or 48 h of alfalfa hay ad libitum, a 48-h feed restriction, and a 24-h refeeding (FRF; n = 5). Blood samples were taken every 15 min during restriction and feeding transitions (0600 to 1400 on d 2 and 4), and every 30 min thereafter until 0830 of the following days (d 3 and 5). In the FRF treatment, plasma concentrations of leptin declined precipitously 6 h after the removal of feed (sample by treatment interaction; P < 0.01), and remained low and unresponsive to refeeding. Similarly, in the RFR group, plasma concentrations of leptin were initially low, and did not respond to feeding during the second (refeeding) sampling period. After feed restriction in each of the 2 treatment sequences, plasma insulin decreased and GH mean concentration, pulse frequency, pulse amplitude, and area under the curve increased (P < 0.05). Refeeding reversed these effects on insulin and GH. These data provide evidence that peripheral concentrations of insulin and GH are dynamically responsive to feed removal (decrease in insulin; increase in GH) and replacement (increase in insulin; decrease in GH), whereas leptin decreases in response to feed restriction but is slow to recover from a transient nutritional insult.
Publication Date: 2006-09-15 PubMed ID: 16971571DOI: 10.2527/jas.2005-741Google Scholar: Lookup
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- Journal Article
Summary
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The research investigates the effects of sudden changes in feeding routines on hormone levels in obese pony mares. Specifically, the study tracks the changes in concentrations of leptin, GH, and insulin during periods of food restriction and refeeding.
Overview of Research Methodology
- The research involved nine obese pony mares of mixed breed that were previously kept on a fescue. They were divided randomly into two groups.
- The groups underwent different treatment schedules. One group (FRF) went through a 48-hour feed restriction, a 48-hour refeeding, and a 24-hour feed restriction. The other group (RFR) had 48 hours of free access to alfalfa hay, followed by a 48-hour feed restriction, and a 24-hour refeeding.
- Blood samples were collected every 15 minutes during restriction and feeding transitions on days 2 and 4, and every 30 minutes thereafter until 0830 of the following days (days 3 and 5).
Research Findings
- Under the FRF treatment, plasma concentrations of leptin (a hormone related to energy balance and body composition) declined sharply 6 hours after the removal of feed and remained low even during the refeeding phase. Similarly, in the RFR group, the leptin concentrations were initially low, and they didn’t respond to the refeeding.
- After feed restriction, plasma insulin (regulates blood sugar) levels decreased, while GH (Growth hormone) concentration, pulse frequency, pulse amplitude, and the area under the curve increased. Refeeding reversed these effects.
- Leptin decreased in response to feed restriction but was slow to recover from a sudden nutritional change, whereas insulin and GH are dynamically responsive to both feed removal and replacement.
Conclusion and Implications
- Changes in nutritional management trigger hormonal responses in ponies.
- These hormonal responses could have significant implications for the metabolic health of the horses, given the known roles of these hormones in energy balance, growth, and blood sugar regulation.
Cite This Article
APA
Buff PR, Spader BR, Morrison CD, Keisler DH.
(2006).
Endocrine responses in mares undergoing abrupt changes in nutritional management.
J Anim Sci, 84(10), 2700-2707.
https://doi.org/10.2527/jas.2005-741 Publication
Researcher Affiliations
- Division of Animal Sciences, University of Missouri, Columbia, Missouri 65211, USA.
MeSH Terms
- Animal Nutritional Physiological Phenomena
- Animals
- Eating / physiology
- Female
- Growth Hormone / analysis
- Growth Hormone / physiology
- Horses / physiology
- Insulin / blood
- Insulin / physiology
- Leptin / blood
- Leptin / physiology
- Obesity / physiopathology
- Obesity / veterinary
- Random Allocation
- Time Factors
Citations
This article has been cited 1 times.- Durham AE, Frank N, McGowan CM, Menzies-Gow NJ, Roelfsema E, Vervuert I, Feige K, Fey K. ECEIM consensus statement on equine metabolic syndrome. J Vet Intern Med 2019 Mar;33(2):335-349.
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