Tens of thousands of abattoir works across the country are today at home after cyber attacks forced the shutting down of all JBS plants in Australia, plus many more in the United States.
Little is known about the attack other than all of the company's information technology systems were affected and workers arriving this morning were told facilities would be unable to operate.
Agents, feedlots and transport operators across Australia have also been asked to hang onto livestock that were destined for JBS indefinitely.
Analysts estimated around 8500 head of cattle and 6500 sheep were scheduled to be processed at JBS facilities today.
Australian Meat Industry Employees' Union Queensland Secretary Matt Journeaux said the situation had not before been seen in meat processing in Australia.
He said speculating on who was behind the attack or why was not helpful at this stage, nor was it possible to say how long the plants might be down.
JBS was working at full speed to get systems back up and operating and until that could occur, processing could not take place, he said.
Queensland has experienced the greatest exposure with six plants down, affecting thousands of workers.
JBS is Australia's largest meat processor.
Agents in Queensland said it was unlikely the development would affect tomorrow's store sales, with few producers likely to hold back cattle as a result.
Mr Journeaux said the company had managed to get its payroll back up and running, so pays would be processed today, which is the scheduled pay day.
A key concern for the union was the number of people who are hired on a daily basis, given the limited availability of livestock at the moment. They are only paid when they work.