Ryegrass Staggers

Over the last couple of weeks we have diagnosed cases of Ryegrass Staggers in both cattle and sheep in the Haka Valley. Outbreaks of ryegrass staggers occur mainly in summer and autumn in sheep grazing perennial ryegrass containing the fungus Neotyphodium lolii. This fungus produces toxins which in turn affect neurological function and the following clinical signs may be seen:

• Trembling of the head and twitching of muscles over the neck and flank

• Head nodding

• Erratic limb movements

• Balance issues (hence “staggers”)

• Eventual collapse with worsening symptoms - with head extension and rigid legs

Clinical signs arise roughly 7-10 days after ingestion of toxins. While direct death from ryegrass staggers is rare, losses arise from sheep with clinical signs being caught in ditches or fences.

A quick fix to ryegrass staggers is not available and treatment recommendations involve moving to safer pasture or feeding out an alternative feed source and ensuring the affected sheep are in paddocks with few hazards. Mycotoxin binders are often marketed to help, but little scientific data proves their efficacy.

Long term strategies to control ryegrass staggers are often expensive but are effective. These include:

• Avoid grazing of ryegrass during risk periods (late summer/autumn)

• Grow rape or other fodder for late summer grazing

• Develop lucerne paddock

• Feed silage