Magnesium
What it does
Magnesium acts as a helper in a large number of enzymatic reactions and is involved in signal transmission between nerve and muscle. It is stored mainly in bone and muscle.
Why it matters
A ration sufficiently supplied with magnesium supports exactly those processes that go unnoticed as long as they work — muscle activity and nerve conduction. They usually become noticeable only when something is missing.
When it becomes critical
Genuine undersupply is rare and most likely on intensively fertilised, species-poor pasture grass. What is then observed is over-excitability, muscle tremor and tension up to cramping. A healthy horse tolerates surpluses well; caution applies only when magnesium AND phosphorus are both supplied generously — that combination raises the risk of urinary sand.
How much a horse needs
Maintenance is quoted as 53 mg per kilogram of metabolic body mass per day (kg BW^0.75); in everyday terms roughly 4 g daily at 300 kg and 6 g at 600 kg. Work adds a little, lactation and growth a good deal more.
Ruhiger Taktgeber im Stoffwechsel; beteiligt an zahlreichen enzymatischen Vorgängen und am Zusammenspiel von Nerven und Muskulatur; Speicher in Knochen und Muskeln.
Pferdefütterung (Vervuert/Coenen), 6. Aufl. 2019, Georg Thieme Verlag; Bedarfswerte nach GfE 2014. Tox-Obergrenze aus Equine Applied and Clinical Nutrition (Geor/Harris/Coenen), Tab. 10-4, S. 194 (Datenbasis dort: NRC 2005 / Poppenga 2001 / GfE 2013).
Cited values
| Type | Value | Unit / context | Source |
|---|---|---|---|
| Requirement | 4 | g/Tag (Erhaltung, 300 kg) | Pferdefütterung (Vervuert/Coenen), 6. Aufl. (2019, Tab. 4.17, S. 99-100 (GfE 2014), Zeile Erhaltung) |
| Requirement | 6 | g/Tag (Erhaltung, 600 kg) | Pferdefütterung (Vervuert/Coenen), 6. Aufl. (2019, Tab. 4.17, S. 99-100 (GfE 2014), Zeile Erhaltung) |
| Requirement | 53 | mg/kg metabolische Körpermasse/Tag (Erhaltung) | Pferdefütterung (Vervuert/Coenen), 6. Aufl. (2019, S. 103 (Text) und Tab. 3.14, S. 61 (Zeile Erhaltungsbedarf, Spalte Mg)) |
| Toxic from | 8 | g/kg Futter-TS | Equine Applied and Clinical Nutrition (Geor/Harris/Coenen) (2013, Tab. 10-4, S. 194 (Safe upper limit)) |
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.
“Metabolic body mass” is a calculated figure, not a weight: body weight to the power of 0.75. For 600 kg that is about 121 — the requirement is multiplied by that figure, not by 600. This is why the number looks small when it is not.
Possible deficiency signs
- Übererregbarkeit und Schreckhaftigkeit, Muskelverspannungen bis Krämpfe (am ehesten auf intensiv gedüngten, einseitigen Grasweiden).
Interactions
- Magnesium ↔ Phosphor (reichlich Magnesium plus reichlich Phosphor erhöht das Risiko für Harngries)
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.
- Pferdefütterung (Vervuert/Coenen), 6. Aufl. 2019, Georg Thieme Verlag; Bedarfswerte nach GfE 2014. Tox-Obergrenze aus Equine Applied and Clinical Nutrition (Geor/Harris/Coenen), Tab. 10-4, S. 194 (Datenbasis dort: NRC 2005 / Poppenga 2001 / GfE 2013).