Influences of different dietary contents of macrominerals on the availability of trace elements in horses.
Authors: Neustädter L-T, Kamphues J, Ratert C
Journal: Journal of animal physiology and animal nutrition
Summary
# Editorial Summary When the German Society for Nutrition (GfE) revised their macromineral recommendations for horses downward, the practical implications for supplement formulation remained unclear—particularly whether reducing calcium, phosphorus and magnesium intake might improve trace element availability. Neustaedter and colleagues conducted balance studies on three adult ponies over sequential 22-day feeding periods, comparing apparent digestibility, retention and serum concentrations of copper, zinc and selenium when hay-based diets were supplemented with either full macromineral content or a reduced mineral formulation. Remarkably, no statistically significant differences emerged in copper, zinc or selenium digestibility or serum levels between the two dietary approaches, despite the native hay already exceeding the revised macromineral recommendations. For practitioners managing horses at maintenance on forage-based diets, this finding suggests that additional macromineral supplementation offers no metabolic advantage for trace element absorption and may represent unnecessary expense, though the authors note that no adverse interactions occurred either. A important caveat: this work was limited to maintenance conditions in adult ponies and may not extrapolate to growing youngstock, pregnant or lactating mares, or high-performance horses with elevated trace element demands.
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Practical Takeaways
- •Horses on hay-based maintenance diets may not require additional macromineral supplementation if hay quality is adequate, potentially reducing feeding costs
- •Reducing macromineral supplementation does not impair trace element (Cu, Zn, Se) absorption or serum levels in adult horses
- •Verify actual hay macromineral content before supplementing, as quality forage may already meet revised nutritional guidelines
Key Findings
- •Apparent digestibility of copper, zinc, and selenium was not significantly affected by macromineral supplementation status (p ≤ 0.05)
- •Serum concentrations of copper, zinc, and selenium remained unchanged between diets with and without macromineral supplementation
- •Native hay macromineral content already exceeded revised GfE recommendations for adult horses at maintenance
- •Macromineral supplementation of hay-based diets for adult horses at maintenance showed no nutritional necessity and no negative effects on trace element metabolism