The Problem With Free Choice Minerals
Most of us have heard at some point. "Just put free choice minerals out and the horses will take what they need."
It's an appealing idea. We like to think our horses have an inbuilt nutritional wisdom that tells them exactly what their bodies require. If they're short of something, they'll eat it. If they don't need it, they'll leave it alone.
Wild horses appear to exhibit this kind of foraging. Wild horses and domestic horses have the same mineral requirements, but they obtain those minerals very differently.
Wild horses spend 14 to 18 hours a day moving and grazing across large areas. By constantly browsing different plants, soils, shrubs, and water sources, they consume a far more varied diet than most domestic horses. That variety helps them balance many minerals naturally over time. Feral horses are also known to visit natural mineral deposits, salt licks, clay soils, or specific watering points that contain higher concentrations of important minerals such as sodium, calcium, magnesium, and trace elements.
Domestic horses live under very different conditions. They are usually confined to a paddock or stable and can only eat what is provided within that area. Most modern pastures contain limited mineral diversity, especially where soils are deficient in copper, zinc, selenium, or iodine. Because domestic horses cannot simply walk 20 km to another grazing area or seek out a natural salt deposit, owners often provide salt blocks, ration balancers, fortified feeds or pellets to make up the shortfall.
Wild horses' “perfect diet” is a myth
From an evolutionary perspective, wild horses are not receiving a "perfect" mineral intake. They can and do develop deficiencies when the landscape lacks certain nutrients. However, natural selection tends to remove individuals that cannot cope, whereas domestic horses are expected to maintain optimal health, reproduction, athletic performance, hoof quality, and longevity far longer than this would occur in the wild.
Chronic health problems caused by mineral imbalances often develop slowly over many years. Conditions such as poor hoof quality, degenerative joint changes, reduced reproductive performance, metabolic dysfunction, or other long-term effects of trace mineral deficiencies may not become obvious until a horse reaches middle age or later. Because feral horses generally have shorter life spans from drought, injury, disease, parasite burden, predation, or resource scarcity, relatively few individuals survive to the advanced ages commonly seen in well-managed domestic horses.
As a result, some mineral-related conditions that are regularly observed in domestic populations may be less apparent in feral herds, not necessarily because deficiencies are absent, but because fewer feral horses live long enough for the cumulative effects to become clinically evident. This can create the misleading impression that wild horses thrive without mineral supplementation, when in reality the consequences of nutritional shortfalls may simply be masked by a shorter average lifespan.
Pica / Geophagia
"Pica" is the general term for a horse eating non‑food items. When a domestic horse strips bark from trees or consumes soil, owners sometimes assume the horse is bored. While boredom can contribute, these behaviours may also represent an attempt to obtain minerals, fibre, plant compounds, or simply perform natural exploratory foraging behaviours. In other words, the horse may be using the limited options available in its environment to mimic the broader dietary choices available to a free-ranging horse.
Geophagia, the deliberate consumption of soil or clay, has been documented in many herbivore species. In wild equids and other grazing animals it is thought to provide access to minerals, buffer toxins from plants, influence gut function, or address specific nutritional shortfalls. Similarly, bark chewing may provide fibre, trace nutrients, secondary plant compounds, or simply satisfy a natural motivation to browse a wider range of vegetation than pasture grass alone can offer.
This does not mean that every horse eating dirt or ringbarking trees has a mineral deficiency. Some horses do it out of habit, curiosity, social learning, lack of pasture, or because the behaviour has become rewarding in itself.
The key question for owners is “What need might the horse be trying to meet?" Evaluating forage quality, mineral balance, salt availability, dietary diversity, and opportunities for natural browsing often provides more insight than treating the behaviour as a problem in isolation.
Free Choice Salt
Part of the confusion that domestic horses will consume minerals they need if it is offered comes from salt. Horses are actually fairly good at regulating their salt intake. Many owners have noticed their horses suddenly becoming interested in salt after hard work, hot weather or extended sweating. It's easy to see this and assume they can do the same thing with every other mineral in their diet.
But even salt intake is variable. Some horses will demolish a block in record time. Others barely acknowledge it's there. If horses could perfectly identify every nutritional deficiency, you'd expect much more consistency.
The general acceptance of free choice salt does not transfer over to other minerals.
Many owners assume that because their horse isn't touching the mineral block, or free choice minerals they must not need anything. But a lack of interest doesn't prove a diet is adequate. In the same way, a horse enthusiastically consuming a supplement doesn't automatically mean they've identified a specific deficiency. Palatability is a big issue. Most commercially available mineral blocks contain a palatiser like molasses. This can result in horses eating more than their requirement because it tastes good.
Many trace minerals have a narrow margin of safety. Unlike macrominerals such as calcium or phosphorus, which are required in relatively large amounts, trace minerals are needed in tiny quantities measured in milligrams. The difference between "not enough," "enough," and "too much" can sometimes be surprisingly small. Selenium is perhaps the best-known example in Australia. Horses require selenium for normal muscle function and antioxidant activity, but excessive intake can lead to toxicity, causing problems ranging from hoof abnormalities and hair loss to potentially serious health consequences.
When trace minerals are mixed with highly palatable flavourings such as molasses or apple flavours, horses may consume the supplement because they enjoy the taste rather than because they have a physiological need for the minerals it contains. The risk of toxicity increases.
When are Free Choice Minerals Appropriate?
Free-choice minerals can absolutely have a place in some management systems. The mistake is assuming that simply providing them guarantees the horse will consume the right amount at the right time.
Free-choice minerals are most appropriate when the product is designed to provide mostly salt rather than precise trace minerals, and where horses have access to a large, varied environment. For example, a group of horses on several hundred acres of native grazing country may benefit from access to a plain salt lick (such as our Himalayan bocks) or a relatively low-concentration mineral block. In this situation, the supplement acts as a nutritional safety net. Horses can choose to use it when needed, and small variations in intake are less likely to create major imbalances because the horses are obtaining most of their nutrition from a diverse range of forages across a large area.
Free-choice minerals may also be useful as a temporary tool to ensure sodium intake during hot weather, lactation, heavy work, or periods when pasture quality fluctuates. As above, salt is one nutrient that horses generally regulate reasonably well, and deficiency is common enough that providing free access is often considered good management.
The important distinction is that free-choice systems tend to work best when the goal is to provide access to nutrients with a wide safety margin, such as salt or calcium, rather than to accurately deliver trace minerals such as selenium, iodine, copper, or zinc.
One of the biggest challenges with free-choice minerals in a shared paddock is that there is no practical way to know how much each horse is actually consuming. Dominant horses may monopolise access, timid horses may avoid the feeder altogether, and intake can fluctuate with season, forage availability, workload, and individual taste preferences. As a result, one horse may receive far less than its nutritional requirements while another consumes considerably more than intended. This creates a significant challenge when dealing with trace minerals, where both deficiencies and excesses can have long-term health consequences.
In contrast, feeding a measured daily supplement allows owners to provide consistent nutrition and maintain appropriate mineral ratios across the whole herd.
Once the objective becomes meeting specific trace mineral requirements and maintaining correct mineral ratios, measured daily supplementation removes the guesswork about individual intake.
Trace Mineral Mixes
Getting the ratios right is often just as important as providing the minerals themselves. While some ingredients are naturally appealing to horses, others are included because they serve an important nutritional purpose, not because they taste delicious.
In fact, many of the minerals horses require are not particularly palatable at all. At Sound Advice we don’t add fillers and flavours to any of our supplements. Nutritional value always comes first. Our goal is to provide horses with exactly what they need, not simply what they would choose from a buffet.
Of course, we also understand that a supplement only works if the horse actually eats it. We always encourage owners to introduce any of our supplements slowly. Acceptance will vary from horse to horse, but generally a half dose or quarter dose well-mixed into damp feed over the first week will help with sifting out.
For the very picky eaters we also offer “Sounds Yummier”, a fenugreek-based flavour enhancer designed to improve palatability without compromising the nutritional formulation. Fenugreek has been shown in research studies to be a flavour that most horses find highly acceptable, making it a useful option for horses that are reluctant to try a new supplement.
A balanced formula in our Trace Mixes provides the nutrition, and Sounds Yummier helps make sure it reaches the horse.
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