Iodine
What it does
From iodine the thyroid builds its hormones, and those hormones help set the pace at which metabolism works. Only tiny amounts are needed — but reliably.
Why it matters
A few milligrams decide over a control loop that affects the entire body. In ration calculation, iodine is therefore an item you do not estimate but compute.
When it becomes critical
Unusual about this nutrient: too little and too much lead to the same picture, an enlarged thyroid. Seaweed preparations in particular often carry unexpectedly high amounts and slip unnoticed into excess. What is called for is the sparingly measured, correct amount.
How much a horse needs
Maintenance: around 1.6 mg daily at 500 kg, equivalent to 0.2 mg per kg of feed dry matter. With an upper limit of 4 mg per kg of feed, little room remains.
Baustein der Schilddrüsenhormone, die den gesamten Stoffwechsel takten. Sowohl zu wenig als auch zu viel stört dieselbe Drüse.
Equine Applied and Clinical Nutrition (Geor/Harris/Coenen), Tab. 10-4, S. 194 (I 5). Besonders zu beachten, weil Seealgen-Zusätze sich unbemerkt aufaddieren.
Cited values
| Type | Value | Unit / context | Source |
|---|---|---|---|
| Requirement | 0.1 | mg/kg Futter-Trockenmasse (Erhaltung) | Equine Applied and Clinical Nutrition (Geor/Harris/Coenen) (2013, Tab. 10-4, S. 194) |
| Requirement | 0.19 | mg/kg Futter-Trockenmasse (traechtig) | Equine Applied and Clinical Nutrition (Geor/Harris/Coenen) (2013, Tab. 10-4, S. 194) |
| Requirement | 0.14 | mg/kg Futter-Trockenmasse (laktierend) | Equine Applied and Clinical Nutrition (Geor/Harris/Coenen) (2013, Tab. 10-4, S. 194) |
| Requirement | 0.26 | mg/kg Futter-Trockenmasse (Wachstum) | Equine Applied and Clinical Nutrition (Geor/Harris/Coenen) (2013, Tab. 10-4, S. 194) |
| Requirement | 0.15 | mg/kg Futter-Trockenmasse (Arbeit) | Equine Applied and Clinical Nutrition (Geor/Harris/Coenen) (2013, Tab. 10-4, S. 194) |
| Tolerance limit | 5 | mg/kg Futter-TS | Equine Applied and Clinical Nutrition (Geor/Harris/Coenen) (2013, Tab. 10-4, S. 194) |
| Maximum per meal | 0.01 | mg je kg Körpermasse und Tag, für ALLE Pferde (500 kg ≈ 5 mg am Tag) | Equine Applied and Clinical Nutrition (Geor/Harris/Coenen) (2013, Kap. 10, S. 222) |
| Maximum per meal | 10 | mg je Tier und Tag bei TRAGENDEN STUTEN (darüber Risiko einer Schilddrüsenstörung beim neugeborenen Fohlen) | Equine Applied and Clinical Nutrition (Geor/Harris/Coenen) (2013, Kap. 10, S. 221) |
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.
A maximum per meal applies per meal and per kilo of horse — not per kilo of feed. Two small meals can add up to more while each stays below the limit.
Sources
- Quelle der Bedarfswerte und fachlichen Angaben: „Pferdefütterung“, Hrsg. Prof. Dr. Ingrid Vervuert und Prof. Dr. Manfred Coenen, 6. Auflage 2019, Georg Thieme Verlag (begründet von Helmut Meyer); Werte nach GfE 2014.
- Equine Applied and Clinical Nutrition (Geor/Harris/Coenen), Tab. 10-4, S. 194 (I 5). Besonders zu beachten, weil Seealgen-Zusätze sich unbemerkt aufaddieren.