Supplementation of Ascorbic Acid in Weanling Horses Following Prolonged Transportation.
Authors: Ralston Sarah, Stives Michelle
Journal: Animals : an open access journal from MDPI
Summary
Prolonged transportation in weanling horses triggers stress-induced depletion of plasma ascorbic acid, compromising immune competence despite the species' ability to synthesise adequate quantities under normal conditions. Ralston and Stives investigated whether oral supplementation could restore circulating ascorbic acid in recently transported weanlings by comparing control animals (no supplementation) with groups receiving 5 g twice daily for either 5 or 10 days post-transport (>50 hours). Whilst both supplemented groups showed modest increases in plasma ascorbic acid concentrations during the treatment period (P < 0.2), a paradoxical decline in plasma levels emerged 1–3 weeks after supplementation ceased, likely reflecting upregulated renal excretion or suppressed hepatic synthesis as a compensatory response. The findings suggest practitioners should consider short-term ascorbic acid support immediately following high-stress transport situations, though extended supplementation protocols warrant caution given the potential for rebound depletion and the risk of disrupting the horse's endogenous regulatory mechanisms during the critical post-stress recovery window.
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Practical Takeaways
- •Ascorbic acid supplementation has minimal benefit for maintaining plasma concentrations in transported weanlings, with modest effects that do not justify routine use
- •If supplementation is considered post-transport, avoid extended protocols as they may trigger counterproductive rebound decreases in plasma levels upon discontinuation
- •Focus management strategies on minimizing transport stress rather than relying on ascorbic acid supplementation to support immune function
Key Findings
- •Ascorbic acid supplementation (5g twice daily) caused only slight (P < 0.2) increases in plasma ascorbic acid concentrations in weanling horses
- •Both supplemented groups showed significantly decreased (P < 0.05) plasma ascorbic acid concentrations for 1-3 weeks after supplementation ceased, possibly due to increased renal excretion or suppressed hepatic synthesis
- •Prolonged supplementation should be avoided due to rebound decrease in plasma concentrations following cessation