Grass tetany: low magnesium on lush pasture
Grass tetany is a metabolic disorder caused by low blood magnesium in cattle or sheep grazing lush, fast-growing grass. It is most common during cool, wet spring weather and can be fatal within hours. Animals at risk need a magnesium supply and close checks while grazing.
What signs might you see?
Animals with grass tetany may stagger, twitch, become unusually excitable or suddenly collapse. Cases are often spotted during grazing checks. For example, if you find a cow down in a fresh ryegrass paddock, note the date, which paddock she was in and the magnesium supplement being used.
How can you reduce the risk?
Provide a magnesium supplement before animals move onto lush grass, and introduce new pasture gradually. Note which groups received supplements and when, so you can check last spring's preparations when planning the next turnout.
Questions from the farm
Why can lush grass trigger it?
Fast-growing grass can be high in potassium and low in magnesium, making it harder for animals to absorb enough magnesium. Cool, wet weather increases the risk.
Which animals are most at risk?
Cows and ewes producing milk are at greatest risk on lush spring pasture. Plan magnesium supplements before moving them onto new grass.
How HerdMobile helps
Bring your animals, feed stocks and farm accounts together on your Android phone. HerdMobile keeps your daily work moving offline: record events, compare feed quantities and follow sales and payments in one place. Use your own feeds and herd information to prepare a ration, then keep a backup file under your control.
Use HerdMobile to note when each group receives magnesium supplements, then look back at previous seasons when planning spring turnout.
