Grass Staggers In Cattle And Sheep

What is Grass Staggers? 

  • Grass staggers is a metabolic disorder of cattle and sheep.
  • The correct medical term for this condition is hypomagnesaemia and it can also be referred to as grass tetany, lactation tetany, milk tetany or calf tetany.
  • This disorder occurs when there are low levels of blood magnesium.
  • Staggers results from an inadequate absorption of magnesium from the digestive system.
  • It is a difficult disorder for the animals to control since there is very little magnesium reserves in the animals skeletal structure, and thus a daily intake is required.
  • It commonly occurs in lactating cows when they have just been turned out to grass in the Spring.
  • It can also occur in Autumn when there is a late flush of grass growth.
  • The disorder can be chronic in beef cattle that have been fed a poor quality Winter feed and in outwintered animals.
  • The condition typically occurs on a cold/wet day when the cattle do not consume as much grass as normal.
  • This disease can occur in both adult cattle and calves of beef and dairy breeds.


  • Nervousness.
  • Restlessness.
  • Loss of appetite.
  • Twitching muscles, particularly in the face and the eyes.
  • Grinding of teeth.
  • Hyperirritability.
  • Staggering gait.
  • Violent convulsions.
  • Paralysis.
  • Death. 

Reduction in milk yield may occur in milking cows before an attack.

Often the attack comes on so rapidly that the animal shows no symptoms.

Causes Of Staggers

  • Underfeeding and restricted food intake.
  • Low magnesium content in the diet.
  • Low absorption efficiency.

Other Contributing Factors

  • Excessive rates of nitrogen and potassium fertiliser applied to grass.
  • The rumen pH.
  • The stress caused to the animals by sudden adverse weather conditions such as heavy and persistent rain.

Control Of Staggers

  • Essential to have a regular supply of magnesium in the diet.
  • Availability of free access high magnesium minerals (magnesium oxide).
  • Preferably mix minerals into any supplementary feed such as in-parlour concentrate feed given to dairy cows.
  • Supplementary feeds such as low quality silage, hay or sugar beet pulp which are high in fibre are useful in slowing down the rate of passage of digesta through the intestine and thus increases the length of time for absorption of magnesium to occur.
  • Use of magnesium bullets which lodge in the rumen to slowly release magnesium are a useful alternative.
  • In the event of an attack of grass staggers the vet will administer magnesium to cure the condition.  In accute cases this will be given into the vein using a flutter valve.

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