Grass staggers: When pasture turns deadly

Rachel Rose

| General

| May 20, 2024

Turning cattle out at Spring can be a high-risk time for grass staggers, a rare but fatal condition!

Warm and wet weather can increase the risk of grass staggers, so farmers must stay vigilant.

Grass staggers:

Hypomagnesemia, more commonly known as grass staggers, is a metabolic disorder, which means low blood magnesium levels.

The mineral magnesium is required for energy production, muscle and nerve function. However magnesium is not easily released from body tissues when in high demand, so cattle require a daily intake of magnesium in their diet.

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

What causes grass staggers?
  • Anything that reduces a cows feed intake.
  • Young grass leys.
  • High levels of potassium and ammonia in forage – this can be a result of fertiliser.
  • Spring flush of grass – fast growing grass is low in both magnesium and fibre, so it passes through the gut quickly, reducing mineral and nutrient absorption.
Risk levels:

Pregnant and lactating ruminants are most at risk of developing grass staggers as they lose magnesium in their milk.

Clinical signs:

If a ruminants daily magnesium intake is not met, they can develop neurological signs such as:

  • Carrying their head high.
  • Twitching muscles.
  • If the animal has gone down, you may observe paddling of legs.
  • The first sign can often be a dead animal.
Reducing the risk:

In order to prevent grass staggers, the cows required daily intake of magnesium needs to be met, this can be achieved by:

  • Buffer feeding with extra forage to slow gut transit.
  • Developing a fertiliser policy to avoid creating pastures high in potassium or ammonia in peak grazing season.
  • Considering mixed species leys for grazing at risk livestock.
  • Discussing prevention strategies with your vet.
  • Injectable magnesium under the skin is effective in cases caught early.
  • In more complex cases, a vet needs to be called.
  • Provide mineral licks.
  • Feed mineralised concentrates.
  • Administer magnesium boluses during the risk period.
  • Add soluble magnesium salts to water tanks.
Recording treatments on the Herdwatch App

With the current warm and wet weather this Spring, cattle are at increased risk of grass staggers. It is important to keep your farm records up to date for any future farm inspection. With Herdwatch, you can record any medical treatment administered with a few clicks on your smartphone!

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