Investigations on the Effects of Different Calcium Supply Exceeding the Requirements on Mineral Serum Concentrations and Bone Metabolism in Young Warmblood Stallions.
Authors: Schubert Dana Carina, Neustädter Lisa-Theresa, Coenen Manfred, Visscher Christian, Kamphues Josef
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Excessive calcium supplementation remains common practice despite most forage-based equine diets meeting or exceeding mineral requirements, prompting researchers to quantify the metabolic consequences of over-supplementation in developing horses. Over five months, 30 young warmblood stallions (aged 2–3 years) received either a high calcium diet (2–2.5-fold requirement) or a moderate excess diet (1.5–1.6-fold requirement), both based on hay and oats, with regular blood sampling to assess serum macronutrients, trace elements, and bone metabolism markers (alkaline phosphatase and osteocalcin). Whilst excessive calcium significantly suppressed serum phosphorus levels throughout the trial (reaching p = 0.0002 by completion), neither calcium protocol affected bone remodelling markers, suggesting that physiologically relevant calcium excess does not acutely impair skeletal metabolism in this population. These findings challenge the routine inclusion of macrominerals in supplement programmes and indicate that trace element fortification—rather than blanket calcium addition—should be the primary supplementary focus for forage-fed horses, with implications for reducing unnecessary mineral loading and associated cost in young stock nutrition.
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Practical Takeaways
- •Stop routinely adding calcium supplements to forage-based rations for young horses—hay and oats already provide adequate calcium without risking mineral imbalances
- •Excess dietary calcium (2-2.5× requirement) suppresses serum phosphorus and offers no skeletal benefit, suggesting supplementation may be counterproductive
- •Focus macro mineral supplementation decisions on trace elements (zinc, copper, etc.) rather than calcium if the base diet is hay and grain
Key Findings
- •Ca-Moderate group (1.5-1.6× requirement) showed significantly higher phosphorus serum levels than Ca-High group (2-2.5× requirement) by end of trial (p = 0.0002)
- •Excessive calcium supplementation (2-2.5× requirement) had no measurable effect on bone markers in young stallions over 5 months
- •Forage-based equine diets do not require macro mineral supplementation when requirements are already met by roughage