Sodium
What it does
Sodium distributes water between the cells and the space around them, is involved in muscle and nerve function, and governs when a horse feels thirst at all.
Why it matters
Forage leaves exactly one mineral gap open, and this is it. Where salt is reliably on offer, water intake stays up and circulation and muscle work keep their footing — which matters most in warm weather and after sweating.
When it becomes critical
With a short supply, water intake falls, fatigue sets in earlier, and circulation and performance may give way. Sweat causes substantial additional losses. A freely accessible salt lick covers this simply. An excess is unproblematic in healthy horses with free access to water.
How much a horse needs
Strictly speaking only 2–3 g a day are needed; recommendations add a safety margin and land near 13 g for a 300 kg horse and 23 g for a 600 kg one, rising clearly once sweating starts. Offered salt freely, most horses meter it themselves.
A macro-mineral that regulates the water balance between the cells and the space between them and triggers the feeling of thirst. It is the only macro-mineral that hay and grass do not reliably cover — which is why a supply of salt belongs in the ration.
Cited values
| Type | Value | Unit / context |
|---|---|---|
| Requirement | 0.26 | g/kg feed dry matter (maintenance) |
| Requirement | 0.39 | g/kg feed dry matter (pregnant) |
| Requirement | 0.44 | g/kg feed dry matter (lactating) |
| Requirement | 0.41 | g/kg feed dry matter (growth) |
| Requirement | 3.03 | g/kg feed dry matter (work (10 l of sweat)) |
| Tolerance limit | 23 | g/kg feed dry matter (upper tolerance) |
Careful when comparing: the requirement is given **per day**, the upper limit **per kilogram of feed dry matter**. These are different reference bases and cannot be compared directly. The upper limit is also not a target — it is the amount at which harm begins.
Possible deficiency signs
- Falling water intake and earlier onset of fatigue; considerable amounts are lost through sweat.
- The requirement is most striking under work: at 10 litres of sweat it rises to more than ten times maintenance (0.26 → 3.03 g/kg DM).