What is grass staggers?

Hypomagnesaemia, more commonly known as grass staggers, is a metabolic disorder caused by low levels of magnesium in the blood. Magnesium is essential for energy production, muscle function, and nerve function.

Because magnesium is not easily released from body tissues when demand increases, cattle require a consistent daily intake through the diet. If that intake is not met, animals can quickly become deficient and develop serious clinical signs.

While the annual incidence of grass staggers in the UK is relatively low, recently calved beef cattle make up a large proportion of cases.

What causes grass staggers?

Grass staggers is most likely to occur when cattle do not consume enough magnesium to meet their daily needs. Several management and feeding factors can increase this risk.

• Anything that reduces a cow’s feed intake
• Young grass leys
• High levels of potassium and ammonia in forage, often linked to fertiliser use
• Rapidly growing grass that is low in magnesium and fibre
• Fast gut transit that reduces mineral and nutrient absorption

These conditions can reduce magnesium uptake and make cattle more vulnerable, particularly where intake is already under pressure.

Which cattle are most at risk?

Pregnant and lactating ruminants are most at risk of developing grass staggers because they lose magnesium in their milk. Animals with higher nutritional demand are therefore more vulnerable if dietary magnesium is not consistently supplied.

Clinical signs to watch for

If a ruminant’s daily magnesium requirement is not met, neurological signs can develop quickly. Recognising the warning signs early can make a significant difference.

• Carrying the head high
• Twitching muscles
• Paddling of the legs in animals that have gone down
• Sudden death, which can sometimes be the first sign

Reducing the risk of grass staggers

Prevention depends on making sure cattle receive enough magnesium each day. A proactive feeding and grazing strategy can help reduce the likelihood of cases developing.

• Buffer feed with extra forage to slow gut transit
• Develop a fertiliser policy that avoids creating pastures high in potassium or ammonia
• Consider mixed-species leys for grazing at-risk livestock
• Discuss prevention strategies with your vet
• Provide mineral licks
• Feed mineralised concentrates
• Use magnesium boluses during higher-risk periods
• Add soluble magnesium salts to water tanks where appropriate

Treatment

Injectable magnesium given under the skin can be effective in cases caught early. In more complex or severe cases, veterinary attention is needed immediately.

Because grass staggers can progress rapidly, fast action is essential where the condition is suspected.

Recording treatments on the Herdwatch app

Keeping farm records up to date is an important part of good herd management and helps ensure you are prepared for future inspections. With Herdwatch, you can record medical treatments quickly and easily from your smartphone.

Logging treatments as they happen makes it easier to track animal health, maintain accurate medicine records, and keep important information organised in one place.

Stay ahead of cattle health risks

Grass staggers may be uncommon, but its impact can be severe. By understanding the risk factors, watching for early signs, and putting the right prevention measures in place, farmers can reduce the threat to their herd.

Combining proactive management with accurate treatment records helps support better health outcomes and stronger farm performance.