Hormonal patterns in normal and hyperleptinemic mares in response to three common feeding-housing regimens.
Abstract: We previously reported that a rise in plasma leptin concentrations followed the rise in insulin and glucose in meal-fed horses, whereas horses maintained on pasture had little fluctuations in hormonal patterns. We have also described a hyperleptinemic-hyperinsulinemic condition that occurs in about 30% of our light horse mares of high body condition maintained on pasture. The present experiment was designed to 1) study the effect of 3 common feeding-housing regimens on leptin and other metabolic hormones in mares and 2) determine whether the hyperleptinemic condition interacted with these regimens. Six light horse mares with high body condition (average score = 7) were assigned to 2 simultaneous 3 x 3 Latin squares, 1 with normal mares (leptin = 0.1 to 6 ng/mL) and 1 with mares displaying hyperleptinemia (>10 ng/mL). Three feeding-housing regimens were compared: ad libitum pasture, ad libitum native grass hay in an outdoor paddock, and single morning feedings of a pelleted concentrate and hay at 0700 in a barn. Five days of acclimation to the feeding regimens were followed by a 36-h period of hourly blood collection to characterize the hormonal characteristics. Leptin concentrations were elevated (P < 0.001) in mares predetermined to be hyperleptinemic compared with normal mares, regardless of the feeding regimen. Leptin was greatest (P < 0.01) in mares on pasture and least in mares fed hay. Variations over time (P < 0.01) were present for all hormones and metabolites studied. Glucose and insulin concentrations were greatest (P < 0.01) in mares on pasture, with meal-fed mares exhibiting an immediate rise in plasma concentrations of both after feeding. Mares on hay had low and constant concentrations of glucose, insulin, and leptin, with no apparent fluctuations. Cortisol, prolactin, and IGF-I did not differ with leptin status, whereas GH differed due to feeding-housing regimen (P < 0.02); there was also an interaction of leptin status and feeding-housing regimen for GH concentrations (P = 0.094). It was concluded that 1) estimates of hormonal secretion in horses based on frequent sampling, depending upon the hormone in question, can be profoundly affected by the feeding-housing regimens, and 2) the hyperleptinemic condition persists under differing conditions of feeding-housing.
Publication Date: 2007-06-25 PubMed ID: 17591706DOI: 10.2527/jas.2007-0182Google Scholar: Lookup
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- Journal Article
Summary
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The research article investigates the impact of different feeding and housing conditions on the hormonal patterns of light horse mares, particularly looking at the levels of leptin, a hormone that regulates fat storage in the body. Additionally, the study explores how a condition known as hyperleptinemia, or excessively high leptin concentrations, interacts with these regimens.
Research Objective and Methodology
- The study aimed to investigate two primary objectives: the effect of three different feeding-housing conditions on the hormone leptin and other metabolic hormones in mares, and the relationship between these conditions and hyperleptinemia.
- Six light horse mares with high body conditions were chosen for the study. They were categorised into two groups: one with normal leptin levels and one group with hyperleptinemia (extremely high leptin levels).
- Three different feeding and housing conditions were tested: unlimited access to pasture, unlimited access to native grass hay in an outdoor paddock, and a single morning feeding of a pelleted concentrate and hay in a barn.
- After five days of adjustment to each feeding regimen, blood was collected hourly over a 36-hour period to analyse hormonal concentrations.
Findings
- The study revealed that the leptin concentrations were significantly higher in mares predetermined to be hyperleptinemic compared to normal mares, regardless of feeding and housing conditions.
- Leptin levels were found to be greatest in mares on pasture and lowest in mares fed hay.
- Hormone and metabolites studied exhibited variations over time. Notably, glucose and insulin concentrations were highest in mares on pasture, with meal-fed mares showing an immediate increase in both plasma concentrations after feeding. Mares fed hay displayed low, constant concentrations of glucose, insulin, and leptin, with no apparent fluctuations.
- No differences were observed in cortisol, prolactin, and insulin-like growth factor-I (IGF-I) levels related to leptin status. However, blood growth hormone (GH) concentrations varied with the feeding-housing regimen and showed an interaction with leptin levels.
Conclusion
- The study concluded that hormonal secretions in horses, depending on the specific hormone, can be significantly influenced by their feeding and housing conditions.
- The study also confirmed that hyperleptinemia persists regardless of different feeding and housing conditions.
Cite This Article
APA
Storer WA, Thompson DL, Waller CA, Cartmill JA.
(2007).
Hormonal patterns in normal and hyperleptinemic mares in response to three common feeding-housing regimens.
J Anim Sci, 85(11), 2873-2881.
https://doi.org/10.2527/jas.2007-0182 Publication
Researcher Affiliations
- School of Animal Sciences, Louisiana Agriculture Experiment Station, Louisiana State University Agricultural Center, Baton Rouge 70803, USA.
MeSH Terms
- Animal Feed
- Animal Husbandry / methods
- Animal Nutritional Physiological Phenomena / physiology
- Animals
- Blood Glucose / analysis
- Blood Glucose / metabolism
- Female
- Growth Hormone / blood
- Horses / blood
- Horses / metabolism
- Housing, Animal
- Insulin / blood
- Leptin / blood
- Poaceae
- Random Allocation
Citations
This article has been cited 1 times.- Schott HC 2nd, Strachota JR, Marteniuk JV, Refsal KR. Long-Term Response of Equids With Pituitary Pars Intermedia Dysfunction to Treatment With Pergolide. J Vet Intern Med 2025 May-Jun;39(3):e70109.
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