Calcium metabolism in ponies fed varying levels of calcium.
Abstract: Calcium metabolism of young, growing ponies fed diets containing 1.5, 0.8 and 0.15% calcium was studied using combined balance and kinetic methods. Variations in calcium intake produced large differences in excretion and retention but had no effect on the level of plasma calcium or on the size of the exchangeable pool. Intestinal absorption, renal excretion and calcium removal from bone responded to the dietary level of calcium to maintain calcium homeostasis. The rates of intestinal absorption and the removal of calcium from the skeleton increased while renal excretion decreased in response to low intake. Opposite responses occurred on a high intake. In contrast to the rate of removal, the rate of deposition of calcium in the skeleton was insensitive to calcium intake and retention. Endogenous fecal calcium excretion was unaffected by dietary calcium. The calcium requirement for horses was estimated by assuming that the endogenous fecal excretion was the major obligatory loss. The horse must absorb about 2.5 g of calcium/day per 100 kg in order to balance the obligatory loss. A dietary level of about 5 g/day per 100 kg is necessary assuming 50% absorption. A similar estimate of the calcium requirement was obtained by extrapolating retention to zero absorption.
Publication Date: 1970-08-01 PubMed ID: 5495848DOI: 10.1093/jn/100.8.955Google Scholar: Lookup
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- Journal Article
Summary
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The research study explores the influence of different dietary calcium levels on calcium metabolism in young ponies. The results indicate that variations in calcium intake affect excretion and retention rates but do not impact plasma calcium levels or the calcium exchange pool. Also, the study provides an estimate of the daily calcium requirement for horses, underpinned by an assumption about obligatory calcium loss.
Experimental Design and Subject Diet
- The study examines the metabolic response of young, growing ponies to varying dietary calcium levels. Researchers fed the subject animals with diets containing 1.5, 0.8, and 0.15% calcium.
- The metabolic impacts were evaluated using balance and kinetic methods, providing a comprehensive view of how dietary calcium influences calcium behavior within the body.
Metabolic Impact of Varying Calcium Intake
- Varying levels of calcium intake led to significant differences in excretion and retention of calcium in the ponies, confirming that dietary calcium intake influences internal calcium distribution and usage.
- Surprisingly, these differences in calcium intake did not affect the level of plasma calcium or the size of the exchangeable calcium pool, showing an unexpected resilience of these particular calcium metrics.
- The authors found adaptive responses in intestinal absorption, renal excretion, and bone calcium removal, which responded variably to maintain calcium homeostasis in the ponies’ bodies. When calcium intake was low, the body increased intestinal absorption and bone calcium removal, but decreased renal excretion. These patterns reversed during periods of high calcium intake.
Deposition Rates and Calcium Requirement
- Interestingly, the rate of calcium deposition into the skeleton did not respond to dietary calcium intake variability, showing an insensitivity that suggests a level of metabolic control.
- The endogenous fecal calcium excretion was unaffected by dietary calcium levels, suggesting that this is an obligatory mechanism beyond dietary control.
- The research estimates a dietary calcium requirement for horses – the subject must absorb approximately 2.5 g of calcium/day per 100 kg to counterbalance the obligatory loss expectations.
- After accounting for approximated 50% absorption, this translates to a necessary dietary intake of about 5 g/day per 100 kg. This requirement estimate aligns with a secondary calculation method that extrapolates retention to zero absorption.
Cite This Article
APA
Schryver HF, Craig PH, Hintz HF.
(1970).
Calcium metabolism in ponies fed varying levels of calcium.
J Nutr, 100(8), 955-964.
https://doi.org/10.1093/jn/100.8.955 Publication
Researcher Affiliations
MeSH Terms
- Animals
- Bone and Bones / metabolism
- Calcification, Physiologic
- Calcium / blood
- Calcium / urine
- Calcium Isotopes
- Calcium, Dietary / metabolism
- Castration
- Diet
- Feces / analysis
- Horses
- Intestinal Absorption
- Kinetics
- Male
- Nutritional Physiological Phenomena
Citations
This article has been cited 3 times.- Saastamoinen M, Särkijärvi S, Valtonen E. The Effect of Diet Composition on the Digestibility and Fecal Excretion of Phosphorus in Horses: A Potential Risk of P Leaching?. Animals (Basel) 2020 Jan 15;10(1).
- Sprekeler N, Müller T, Kowalewski MP, Liesegang A, Boos A. Expression patterns of intestinal calcium transport factors and ex-vivo absorption of calcium in horses. BMC Vet Res 2011 Oct 22;7:65.
- Köninger M, von Velsen-Zerweck A, Eiberger C, Löffler C, Töpper A, Visscher C, Reckels B, Vervuert I. Nutrient Composition and Feed Hygiene of Alfalfa, Comparison of Feed Intake and Selected Metabolic Parameters in Horses Fed Alfalfa Haylage, Alfalfa Hay or Meadow Hay. Animals (Basel) 2024 Mar 13;14(6).
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