Seasonal vitamin A depletion in grazing horses is assessed better by the relative dose response test than by serum retinol concentration.
Abstract: Vitamin A influences growth and reproduction in horses. A retinol dose response (RDR) test for retinol has been shown to be better than serum retinol concentration for assessing vitamin A status in other species, so we have compared these two methods in the horse. Forty-five Thoroughbred broodmares were assigned randomly to three groups fed pasture and hay (PH), pasture, hay and vitamin A-free concentrate (PHC), or hay and concentrate (HC) in early summer (May 1991). Mares in pasture groups produced 23 foals (March through June) that had access to their dam's diets and were also studied. In the mares, significant vitamin A depletion developed in 2 mo in the nonpasture group (HC) and in 8 mo in the two pasture groups (PH and PHC) according to the RDR test, and in all three groups at 8 mo as shown by a decrease in serum retinol concentration. In the weanlings (PH and PHC only), no differences between groups were found for serum retinol, but the RDR was significantly higher in the PH group, which had suffered a respiratory infection, than in the PHC group. These findings indicated that vitamin A depletion was detected more readily by the RDR test than by serum retinol concentration, that consumption of pasture delayed depletion in the late fall, and that infection was associated with lower vitamin A status.
Publication Date: 1995-10-01 PubMed ID: 7562108DOI: 10.1093/jn/125.10.2711Google Scholar: Lookup
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- Comparative Study
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research article explores how vitamin A deficiency in grazing horses is more accurately detected using a relative dose response (RDR) test for retinol, compared to the typical method of measuring serum retinol concentration.
Research Methodology and Participants
- The study involved 45 Thoroughbred broodmares which were randomly divided into three groups based on their diet: pasture and hay (PH), pasture, hay and vitamin A-free concentrate (PHC), or hay and concentrate (HC).
- The experiment was conducted in early summer, between March and June, when the mares had 23 foals. These foals were included in the study as they had access to their mothers’ diets.
Key Findings
- The study found that the mares in the group without pasture (HC – hay and concentrate) showed significant signs of vitamin A depletion within 2 months.
- In contrast, the mares in the groups which were pasture-reliant (PH and PHC) showed signs of vitamin A depletion in 8 months.
- Vitamin A depletion in all three groups was noted at 8 months according to a decrease in serum retinol concentration.
- The study found no differences in serum retinol levels for the weanlings in the PH and PHC groups.
- However, using the RDR test, it was found that the weanlings in the PH group had a higher relative dose response due to a respiratory infection experienced by the group.
Conclusions and Implications
- The results indicate that the relative dose response (RDR) test was more reliable in identifying vitamin A depletion in the horses, when compared to the conventional method of measuring serum retinol concentration.
- The findings also suggest that grazing on pasture has a protective effect, delaying vitamin A depletion in horses until the later part of the fall season.
- Lastly, it was noted that infections, like the respiratory ailment that affected the PH group, have a negative impact on vitamin A status in horses.
Cite This Article
APA
Greiwe-Crandell KM, Kronfeld DS, Gay LA, Sklan D.
(1995).
Seasonal vitamin A depletion in grazing horses is assessed better by the relative dose response test than by serum retinol concentration.
J Nutr, 125(10), 2711-2716.
https://doi.org/10.1093/jn/125.10.2711 Publication
Researcher Affiliations
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061, USA.
MeSH Terms
- Analysis of Variance
- Animal Feed / standards
- Animals
- Dose-Response Relationship, Drug
- Female
- Horse Diseases / blood
- Horse Diseases / diagnosis
- Horses / metabolism
- Pregnancy
- Pregnancy Complications / blood
- Pregnancy Complications / diagnosis
- Pregnancy Complications / veterinary
- Random Allocation
- Seasons
- Vitamin A / blood
- Vitamin A / metabolism
- Vitamin A / pharmacology
- Vitamin A Deficiency / blood
- Vitamin A Deficiency / diagnosis
- Vitamin A Deficiency / veterinary
Citations
This article has been cited 1 times.- Tsinopoulos I, Nousia-Arvanitakis S, Galli-Tsinopoulou A, Roubies N, Tentzidou K, Xefteri M, Stangos N. Role of electroretinography in the assessment of retinal function as an indicator of vitamin A status.. Doc Ophthalmol 2000 Nov;101(3):211-21.
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