Ryegrass staggers occurs when animals grazing perennial ryegrass eat large amounts of a toxin produced by ryegrass endophyte, a fungus that grows inside the plant.
The endophyte also produces another toxin that is important to protect the plant from destruction by insects, in particular the Argentine stem weevil.
What does ryegrass staggers look like?
Ryegrass staggers is usually seen late summer to early autumn, especially in dry years when stock graze close to the ground, but can also occur in spring when stock are grazing large amounts of seed heads.
It occurs in sheep, cattle, deer and horses and the signs are usually seen when animals are disturbed and forced to move. The initial signs are a subtle head tremour and twitching of the skin muscles. This can then develop into a more obvious head nod, swaying and a staggering motion and can further worsen to a stiff legged walk and collapse. After a while the animal recovers. Deaths tend to be accidental following injury such as drowning after a fall into water or being caught in fences.
It is important to recognise affected animals and to take preventative steps against ryegrass staggers to prevent these injuries and because it can lead to reduced production such as poor growth rates and reduced milk production.
Sheep & Cattle
|Head nodding and jerky limb movements result in staggering during moving or short prancing steps. Sheep can fall over and appear to be in a spasm.
When the spasm passes they get up and appear to be relatively normal.
|As horses are more closely handled the first sign owners see is a nervous or frequent shying horse. This progresses to unsteadiness and loss of balance when walking.
|Head and neck tremors are the commonest sign, with alpacas being particularly sensitive to the toxin.
What can I do with animals that have ryegrass staggers?
Affected animals should be shifted to ‘safe’ pasture (endophyte free ryegrass or another species of grass such as tall fescue, lucerne, red clover or chicory) or given supplementary feed. However, it should be noted that the toxin can remain present in hay. Movement of the animals should be avoided if possible as this may trigger the onset of staggers and cause injury.
How can I prevent ryegrass staggers happening?
Attempts should be made to avoid hard grazing of ryegrass. This may be difficult during dry summers but can be minimised by feeding additional supplements (such as maize or silage) and shifting stock frequently to prevent pasture covers becoming low.
No scientifically proven treatment options are available for dealing with ryegrass staggers. Some ancedotal farmer evidence shows that by adding Summer Tonic or Nutrimol* (both available from our clinics) to hay or silage or used as a drench in sheep and cattle can help. Mycofix, based on ancedotal feedback from clients is effective. Please contact our clinics for further information on these products.
Other longer term but more expensive options include re-sowing pastures with species of ryegrass with ‘safe’ endophyte that provides protection against insect pests without causing ryegrass staggers or breeding animals that are resistant to ryegrass staggers.