Ryegrass staggers is a neurological condition that
can affect many grazing animals, such as cows,
sheep, deer, alpacas and horses.
What causes it?
Ryegrass staggers is caused by a fungus that lives
inside the ryegrass. This fungus produces several
toxins that can affect livestock. However, some
of the toxins have protective properties for the
ryegrass and can protect ryegrass from attack by
the Argentine stem weevil.
The disease is most common in summer and is
usually worse when ryegrass has gone to seed and
when animals are grazing down to low residuals.
The clinical signs that affected animals show are
what are known as ‘intention tremors’. Animals
become twitchy and have reduced control over
their limbs. Bad cases can result in animals falling
over and struggling to get back on to their feet.
This becomes worse when animals are stressed
and this is commonly noted when calves or lambs
are being brought into yards for drenching in the
summer. Some of the major losses due to ryegrass
staggers is by ‘misadventure’ – animals falling into
drains, fences, drowning etc. Growth rates in
lambs and calves can also be reduced by ryegrass
staggers. There are often several animals in a mob
that are affected, but the severity of the signs can
vary between animals.
Don’t confuse this with grass staggers, which is due
to low magnesium – the major difference in the
two, is that grass staggers/low magnesium cows will
rapidly deteriorate and can die directly from the
low magnesium, whereas ryegrass staggers, animals
improve if they are left alone.
Ryegrass staggers is usually diagnosed on the
clinical signs alone, and by the response after
removing animals from infected pastures.
Treatment and Prevention
There are many products on the market that claim
to have some effect on ryegrass staggers – however,
pretty much all of this is anecdotal and are unlikely
to have any effect. Animals will recover slowly on
their own – care must be taken to not work up
animals showing signs of ryegrass staggers, and any
potentially dangerous areas should be fenced off
e.g. drains, cliffs or steep banks.
If in doubt of the diagnosis, give a magnesium bag
under the skin and call the vets. The only true
immediate ‘treatment’ is to limit the intake of
infected pastures. Although this may be difficult, supplementary feed may need to be
offered to limit the intake of infected ryegrass paddocks. The use
of summer crops will also reduce the impact of ryegrass staggers,
as will avoiding grazing down to very low residuals. Giving animals
access to high energy feeds will assist in recovery.
As the fungus lives inside the ryegrass, fungicide sprays will have no
impact – we would need to kill the ryegrass itself, which wouldn’t
be that helpful….
Virtually all new species of ryegrass have protection against ryegrass
staggers. In fact, this is one of the reasons for improved production
from new cultivators. Ryegrass staggers can be almost completely
prevented with planting new ryegrass cultivators.
Please contact one of the VetEnt Veterinarians to discuss a ryegrass
staggers management plan for your farm.

30 January 2018, 03:54