Grass Staggers (Hypomagnesaemia) and Cattle Welfare

Grass staggers is a potentially fatal condition of grazing cattle and sheep caused by acute magnesium deficiency, with welfare implications from sudden onset neurological disease.

Key Facts

Hypomagnesaemia typically occurs in early spring when cattle are turned out onto rapidly growing grass with high potassium content
Magnesium has no significant body reserve — daily intake from grazing or supplementation is essential for maintaining blood levels
Affected animals show muscle tremors, excitability, staggering, convulsions and may die within hours of first signs
Prevention through magnesium supplementation (calcined magnesite in feed, magnesium buckets or fertiliser) is highly effective

Welfare Considerations

Grass staggers imposes sudden severe welfare suffering — affected cattle progress from mild ataxia to violent convulsions and death within hours. The extreme distress of convulsing cattle and the risk of self-injury from thrashing make this one of the most acute welfare emergencies in cattle practice. IV magnesium treatment provides rapid welfare improvement if administered early enough. Prevention is straightforward and reliable — daily magnesium supplementation through spring and autumn effectively prevents the condition, yet it remains common due to inadequate prevention planning.

What You Can Do

Begin magnesium supplementation 2-3 weeks before spring turnout and continue through the high-risk period
Use multiple supplementation routes (calcined magnesite top-dressed on feed, boluses, lick buckets) to ensure adequate intake
Treat suspected cases immediately with IV magnesium sulphate — do not delay for laboratory confirmation
Inspect grazing cattle twice daily during high-risk spring and autumn periods — early cases are treatable