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Animals : an open access journal from MDPI2022; 12(19); 2510; doi: 10.3390/ani12192510

Dietary Iron Unlikely to Cause Insulin Resistance in Horses.

Abstract: Racehorses are often supplemented extra iron with the expectation that the iron will improve overall performance and health. A survey of 120 U.S. Thoroughbred trainers, representing 1978 Thoroughbreds from various regions of the U.S., was conducted to determine the average amount of dietary iron fed to Thoroughbred racehorses per day. Survey results indicated racehorses were fed an average of 3900 mg of iron per day from hay and grain alone. This exceeds the 0.8 mg/kg BW or 400 mg for a 500 kg working horse that the NRC 2007 recommends per day. Supplements increased the daily average intake of iron by an additional 500 mg Fe. Some equine nutritionists propose that excess dietary iron may be a causative factor in insulin resistance (IR). However, the occurrence of IR in Thoroughbred racehorses is very rare. This study did not find one confirmed veterinary diagnosis of IR in any of the surveyed trainers' Thoroughbred horses, whether racing, on a layoff, or retired. Given the iron content in these diets easily exceeds the NRC minimum daily requirements, it seems unlikely that dietary iron is an independent causative factor in IR.
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Publication Date: 2022-09-21 PubMed ID: 36230253PubMed Central: PMC9559484DOI: 10.3390/ani12192510Google Scholar: Lookup
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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.

This research investigates the occurrence of insulin resistance in Thoroughbred racehorses related to high iron intake. The results suggest that a high iron diet in these horses does not seem to cause insulin resistance, even when the iron intake exceeds the daily required limit.

Objective

While it’s a common belief that iron supplementation can enhance race horse performance, there is a counterargument that excess dietary iron could be causing insulin resistance (IR). This study examined this hypothesis by understanding the average dietary iron intake of Thoroughbred racehorses and any incidence of IR.

Methodology

  • The study surveyed 120 U.S. Thoroughbred trainers, representing 1978 Thoroughbreds, from various regions of the U.S.
  • The researchers gathered data on the average amount of dietary iron these horses were ingesting daily, from hay, grain and supplements.
  • The team also checked for any veterinary diagnosis of IR in these horses, whether they were racing, resting or retired.

Findings

  • Survey results showed that Thoroughbred racehorses are ingesting an average of 3900 mg of iron daily from just hay and grain. This is much higher than the recommended 400 mg daily intake for a 500 kg working horse as per NRC 2007 guidelines.
  • The data also showed that supplements further added an average of 500 mg of iron to daily intake of the horses.
  • Despite this high iron intake, it was found that there were no confirmed diagnoses of IR in any of the trainers’ Thoroughbred horses.

Conclusion

The study indicates that, despite iron intake surpassing minimum daily requirements, it doesn’t seem to cause IR in these racehorses. This refutes the claim that excess dietary iron could be an independent factor causing insulin resistance.

Cite This Article

APA
McLean NL, McGilchrist N, Nielsen BD. (2022). Dietary Iron Unlikely to Cause Insulin Resistance in Horses. Animals (Basel), 12(19), 2510. https://doi.org/10.3390/ani12192510

Publication

Animals : an open access journal from MDPI
ISSN: 2076-2615
NlmUniqueID: 101635614
Country: Switzerland
Language: English
Volume: 12
Issue: 19
PII: 2510

Researcher Affiliations

McLean, Nancy L
  • The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Midlothian EH25 9RG, UK.
McGilchrist, Nerida
  • Equilize Horse Nutrition Pty Ltd., P.O. Box 11034, Tamworth, NSW 2340, Australia.
Nielsen, Brian D
  • Department of Animal Science, Michigan State University, 474 S. Shaw Lane, East Lansing, MI 48824, USA.

Conflict of Interest Statement

The authors declare no conflict of interest.

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