A bird flu outbreak at two egg farms that forced half a million chickens to be culled could rob supermarket shelves of 450,000 eggs per day, as farmers warn biosecurity measures may push up prices.
An outbreak of avian influenza has been confirmed at an egg farm in Terang, 200km southwest of Melbourne.
The site is linked to the Meredith egg farm, about 130km away, where a mass culling of chickens took place on Wednesday after a number of poultry died from a different strain of the same virus, H7N3.
Both are operated by Avgo and Surf Coast Eggs Farms and share management, staff and machinery.
The Terang property was placed under quarantine after Thursday's discovery with a surrounding 1.5km restricted area, while the Meredith farm had a 5km restricted area, with both sites subjected to a broader control area buffer.
More than 500,000 chickens across both farms have been destroyed to contain the spread of the highly pathogenic virus, leaving a significant dent in supplies of eggs, the Victorian Farmers Federation said.
"Birds in their peak production will produce five to six eggs a week," vice president and egg farmer Danyel Cucinotta told AAP.
"In this scenario, you're looking at about 450,000 eggs a day that will be missing from the shelf."
While it's unclear who the farms supply, Ms Cucinotta said eggs produced in particular states are often supplied to supermarkets or the box market interstate.
"It's not as simple as 450,000 eggs missing in Victoria that it is Victorians who will suffer," she said.
"They might supply a distribution of a major supermarket that happens to supply the entire east coast.
"Victoria is probably going to be the hardest hit, but it will obviously impact interstate as well."
Ms Cucinotta said if farmers were forced to increase "costly" biosecurity measures that could push up the price of eggs in coming months.
She said there would always be eggs on supermarket shelves but the flu outbreak could impact accessibility, meaning it might be harder for customers to buy a particular brand.
"You may not find the eggs that you know and love, for argument's sake, on a particular shelf that you're very much accustomed to, but that doesn't mean there's not eggs," she said.
An Aldi spokesman told AAP customers may notice "small gaps on shelves in some stores" over the coming days.
"Currently the impact on our egg product volume is very limited, but like the rest of the industry, we are working with our partners on supply to meet the needs of our customers and to bring supply back to normal levels as soon as possible," he said.
Woolworths told AAP it doesn't expect the outbreak to impact its supply.
Ms Cucinotta estimated it could take between six months to three years for the impacted farms to return to normal production.
"The personal cost to a farmer, I mean mentally, emotionally, as a family, they will need a serious amount of support and help," she said.
An Avgo and Surf Coast Eggs Farms spokesman said the family-run business had been devastated by the flu outbreaks.
"Sadly, it is difficult to protect against avian flu but at such a difficult time, we can rest assured that we have been following all protocols and there is nothing we could have done to prevent this," said in a statement to AAP.
He said there was no cross-contamination between the two farms, with each site infected with a different virus strain and neither variant was new to Australia.