The Department of Agriculture and Food has urged Western Australian horse and other livestock owners to be aware of the risk of annual ryegrass toxicity (ARGT) following recent horse and cattle deaths linked to the consumption of affected hay.
Department veterinary officer Anna Erickson said ARGT was a serious and usually fatal disease that occurred when livestock ate annual ryegrass seed heads infected with a toxin-producing bacterium.
“Annual ryegrass is present in much of the oaten and meadow hay grown and sold for animal consumption in Western Australia,” Dr Erickson said.
“Although ARGT occurs mainly in spring when stock graze pasture containing infected ryegrass seedheads, outbreaks can occur any time of the year from feeding hay that contains seedheads affected by ARGT.”
Dr Erickson said the toxin was cumulative and signs did not appear until a near-fatal dose was ingested.
“The time taken for the animal to show signs of illness depends on the amount of hay or pasture being consumed and the amount of toxin present in the seedheads,” she said.
“Signs include weakness, muscle tremors, loss of coordination, staggering, convulsions and eventual death. The toxin also reduces appetite which can lead to colic or fatty liver syndrome in ponies. Occasionally animals may die before signs are noticed.
“There is no specific antidote to ARGT, but some affected animals will recover with supportive care. Animals are sensitive to external stimuli so should be kept in a quiet area with easy access to feed and water, and handled as little as possible.
“The department recommends that all stock owners and feed sellers ensure hay containing annual ryegrass is tested for the presence of the bacterium that causes ARGT, and testing has found the hay to be low risk. Visual tests are not reliable.”
Dr Erickson said it was important to note that while feed testing reduced the risk of ARGT poisoning, it did not eliminate it as ARGT could be present in other untested parts of the bales.
“Requesting a vendor declaration from the hay supplier is a formal way of receiving a declaration about the feed quality and any testing conducted,” she said.
“Horse owners can obtain fodder vendor declarations from the Australian Fodder Industry Association website while red meat producers can access commodity vendor declarations through Meat and Livestock Australia’s Livestock Production Assurance e-DEC program.
“Landholders should also be aware that bringing infected hay onto their properties may infect their own pastures.”
Stock owners concerned about the safety of the hay already on the property can organise to have hay tested for ARGT risk by the department’s Diagnostic Laboratory Services (DDLS).
Testing requires a 1kg hay sample to be submitted to the laboratory service at the department’s South Perth office or to any regional office.
Dr Erickson said the signs of ARGT were similar to some reportable diseases not present in Australia.
“For this reason, we are always keen to have a private or department vet take samples to submit for laboratory testing from livestock with these signs,” she said.
“These reportable diseases can be ruled out with correct testing. Data from this testing helps to protect public health and our valuable livestock export markets, as trading partners ask us to provide proof that Australia is free of these diseases.”
Media contacts: Jodie Thomson/Lisa Bertram, media liaison +61 (0)8 9368 3797