Warragul's dairy and calf sales have been cancelled due to coronavirus fears.
Nutrien agent Michael Savage said the closure would see the value of both beef and dairy calves crash.
"All the bobby calves will be sold over the scales," Mr Savage said.
"They've been selling particularly well, beef calves up to maybe $280 and friesian heifer calves $500.
"Off the scales you're going to get meat prices of between $40 and $100."
He said the Warragul saleyards had been a source of calves for people who wanted to grow calves out or rear heifers for the export market.
Trafalgar dairy farmer Jim Arbrecht is a regular at the sales and said the closure was unnecessary.
"It's completely different to a store sale: there are only six or seven actual buyers at a calf sale and it's nothing to just keep them apart," he said.
"There might be 15 or 20 onlookers but people are getting very used to being spread out and they could be kept away from the buyers.
"In fact, if all the bull and fat cattle sales had been kept open at Warragul that would have taken a lot of pressure off Koonwarra and Pakenham.
"A local carrier took 500 or 600 cattle to Pakenham from the district one day last week and they're so overwhelmed, they're weighing cattle as late as 1.30 in the morning.
"Warragul had cattle ready to go on trucks within an hour and a half of the sale finishing.
"It was averaging 429 cows and bulls a week, every week.
"It's sheer incompetence on the behalf of the VLE and someone needs to stand up and say it."
But Nutrien agent Michael Savage was more cautious.
"It's awkward because the more people you get at a sale, the more chance you have of spreading this virus," he said.
"It's alright to say it's very important for stock agents to do their jobs and service their clients but the worst thing they can do is get their clients to come to the markets and get infected."
Alex Scott & Staff Warragul agent Neil Darby said the saleyards' owner, Victorian Livestock Exchange (VLE) had made the decision to close the yards.
"They wouldn't have made that decision lightly," Mr Darby said.
"I always knew store sales were going to be a tough thing to keep going with the amount of people who attend.
"As far as the calf market and the dairy sale goes, look, I'm not qualified to make that decision really but you're not allowed to have that many people at home, so it's going to be difficult.
"I would have thought they could have rung us and had some consultation with us to work out a process around it but no, they haven't, the VLE have just gone bang, that's it.
"By the same token, I don't want to risk anyone catching the coronavirus."
Mr Darby said it was too early to discuss any contingency plans for dairy cow and calf sales but he would help to connect any buyers and vendors.
There's speculation that the coronavirus could hasten the closure of the Warragul saleyards.
"I would be very, very surprised if Warragul reopens after this," Mr Savage said.
VLE managing director Wayne Osborne said the market cancellations were not expected to lead to the permanent closure of Warragul.
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