Wimmera rye grass toxicity in Western Australia.

Area of Science:

• Veterinary Pathology
• Agricultural Science
• Parasitology

Background:

• Wimmera rye grass (Lolium rigidum) can be parasitised by Anguina species and Corynebacterium species.
• Parasitised Wimmera rye grass has been implicated in livestock toxicity outbreaks.

Purpose of the Study:

• To investigate Wimmera rye grass toxicity outbreaks in Western Australia.
• To determine the distribution of Wimmera rye grass parasitised by Anguina sp and Corynebacterium sp.

Main Methods:

• Field investigation of 58 outbreaks on 26 farms between 1970 and 1974.
• Observation of clinical signs and gross autopsy findings in affected sheep and cattle.
• Assessment of attempted control measures.

Main Results:

• Outbreaks occurred in various grazing and feed situations containing parasitised Wimmera rye grass.
• High morbidity rates (up to 77%) and mortality were observed in sheep and cattle.
• Clinical signs included neurological deficits; gross findings included pale liver and haemorrhages; no specific histopathology was identified.

Conclusions:

• Wimmera rye grass parasitised by Anguina sp and Corynebacterium sp caused significant livestock toxicity.
• Current symptomatic and agronomic control methods were ineffective.
• Further research into effective control strategies is warranted.