The key is not only the amount of each mineral, but above all their proportions and bioavailability. Calcium, phosphorus and magnesium must stay in balance if they are to support healthy bone and muscle. The Ca:P ratio in adult horses should be about 1–3:1, and disturbing that proportion, whether through shortfalls or excesses, can lead to weaker bone, digestive problems or muscle tension. The balance between iron, zinc, copper and manganese is just as important. These elements compete with one another for absorption, so supplementing “by eye”, or using several products at once, often ends, paradoxically, in… shortfalls.
Mineral shortfalls develop gradually. Horses with poor mineralisation may have hoof problems, a dull coat, tight muscles or weaker immunity. Young horses may show growth disturbances, and sport horses poorer recovery and a drop in form. Simply adding “something for the hooves” or “something for the muscles” does not solve the problem if the basic balance of the ration is missing.
On the other hand, too many minerals is just as dangerous. An overdose of selenium, for example, can lead to serious neurological disturbances and hoof problems. Too much iron, meanwhile, weakens immunity and makes it harder to absorb copper and zinc. An excess of calcium can disrupt kidney function and change how other elements are absorbed. Excesses most often come not from the feed itself, but from combining several supplements without a plan, or from using products with a similar composition under different names.
When judging whether a horse’s diet is properly balanced for minerals, it is worth looking at the composition of the concentrate – a well-chosen one should make up the natural gaps. The presence of a salt lick or of chaff with added minerals also matters, as does a close look at every supplement used at the same time. Products “for joints”, “for hooves” or “for immunity” often contain similar ingredients and can lead to an overdose without anyone realising.
Remember that sport horses have a greater need for electrolytes and for the trace elements involved in recovery, but that does not always mean adding yet another product. Often a well-chosen, complete feed with minerals of high bioavailability is enough to keep the balance without overloading the body.
To sum up, mineral balance is the foundation of health, but at the same time the hardest part of feeding to judge on your own. Both shortfalls and excesses can have a marked effect on the horse’s condition, fitness and general wellbeing. The key is awareness, looking at the whole ration, and caution with supplements. If a horse has problems with its coat, hooves, recovery or muscle tension, it is worth running blood tests and, if needed, discussing the diet with a nutritionist.