Ryegrass staggers occurs due to the intake of mycotoxins produced by a fungus (Acremonium lolii) that is associated with endophytes in ryegrass. Different types of ryegrass contain differing amounts of endophytes. These are found in plant tissue and seeds but are concentrated in the lower leaves. The disease is therefore most likely to occur in summer when the pasture is short and animals are grazing close to the ground.
Individual animals vary in susceptibility to the mycotoxins with a range 5 to 75% being affected. Clinical signs vary according to the amount of toxin consumed and range from animals appearing ‘drunk' and un-coordinated (eg unsteady head carriage, high stepping or crossing front legs) to being ‘down' and unable to stand at all. Often animals may appear normal until stressed (eg moved or yarded) and will then fall over and may remain down for several minutes before recovering. Death is NOT a common outcome except indirectly through misadventure. Animals still eat and drink as normal.
The key to treatment is early recognition and removal of affected animals from contaminated pasture. They need to be kept as quiet as possible and avoid stress wherever possible. Provide them with supplementary feed and water, and keep them in an area that is well fenced and free from potential hazards (eg streams, dams, loose wire, and debris).
Prevention of ryegrass staggers is difficult. Try not to allow animals to graze potentially toxic pasture for more than 2 to 3 hours per day unless it is greater than 30cm in height. Low endophyte pastures are available, and grazing animals on plants such as chicory and plantain mixes will help to avoid exposure to the toxin.
For more information on prevention of ryegrass staggers, please contact us at either of the Totally Vets branches.
