Ryegrass Staggers

Seasonal conditions over the past few weeks have resulted in a large number of reports of ryegrass staggers throughout the district.

Animals affected:

  • Cattle, predominantly calves and yearlings.
  • Sheep, adults and weaners
  • Alpacas
  • Horses, very occasionally
Signs Observed: (more than one animal in the group will be affected)
  • Head movements, usually weaving from side to side.
  • Stiff legged gait noticeable, particularly in the front legs.
  • The signs are exacerbated with movement. Often animals are almost normal until they are driven when the "proppy" gait is noticeable.
  • Eventually they may fall over and while struggling are unable to rise.
  • If left alone, most animals will eventually get up.
Cause:
Rye grass staggers is caused by a toxin associated with a fungus called an endophyte that lives in the ryegrass plant. There is a positive correlation between plant yield and presence of endophyte, so that newer varieties of ryegrass that have higher dry matter yields tend to have more endophyte than some of the older varieties.
Management:
The toxin is very rarely fatal and most deaths occur due to misadventure eg. affected calf drowns in mud on a dam bank. There is no specific treatment. Like any poisoning, the logical approach is to remove the animals from the source of the toxin.

If animals are removed to an unaffected pasture, the signs will disappear in a few days to weeks. Alternatively, reducing the intake of pasture by feeding hay, silage or grain will reduce the severity of signs.



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