A Meta-Analysis on Quantitative Calcium, Phosphorus and Magnesium Metabolism in Horses and Ponies.
Authors: Maier Isabelle, Kienzle Ellen
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary: Calcium, Phosphorus and Magnesium Metabolism in Horses and Ponies Re-evaluating mineral requirements in horses and ponies has become increasingly important as nutrition science advances, yet recommendations have remained largely unchanged for decades. Maier and Kienzle conducted a comprehensive meta-analysis of 42 studies to recalculate factorial requirements for calcium, phosphorus and magnesium by plotting metabolic data against intake levels—a rigorous approach that accounts for endogenous faecal losses and distinguishes between organic (feed-derived) and inorganic (supplemental) mineral sources. Their findings reveal species and source-dependent differences that warrant practice changes: ponies require approximately half the currently recommended magnesium intake whilst horses need 1.9 times the current recommendation; organic calcium sources show superior digestibility and lower endogenous losses compared to inorganic forms; and critically, water-soluble inorganic phosphorus sources cause hyperphosphatemia and hyperphosphaturia even at modest intakes, suggesting they pose genuine health risks and should be avoided in equine diets. For practitioners formulating rations, this meta-analysis indicates that mineral source matters considerably—organic minerals perform better for calcium, whilst phosphorus requirements and safety profiles depend heavily on the solubility characteristics of supplemental sources, necessitating more careful evaluation of commercial mineral products and feed labels than current practice often demands.
Read the full abstract on PubMed
Practical Takeaways
- •Adjust magnesium supplementation based on animal type—ponies need significantly less than horses; current recommendations overestimate pony requirements
- •Prioritize organic calcium sources and avoid highly water-soluble inorganic phosphorus supplements to prevent metabolic complications and hyperphosphatemia
- •When using insoluble phosphorus sources, increase dietary phosphorus above standard recommendations to meet true bioavailability requirements
Key Findings
- •Ponies require approximately half the current recommended magnesium intake compared to horses, while horses require 1.9 times the currently recommended amount
- •Organic calcium sources demonstrate higher true digestibility and lower endogenous losses compared to inorganic sources
- •Water-soluble inorganic phosphorus sources cause hyperphosphatemia and hyperphosphaturia even at low intakes, posing potential health risks
- •Insoluble phosphorus sources require higher factorial dietary requirements than current recommendations due to lower digestibility