Australia's largest chicken egg is 209 grams and was laid at Bungaree farm

Eddy Cusack, 10, with with the eggstraordinary find before it was cracked open on Friday. Picture: Karleen Minney
Eddy Cusack, 10, with with the eggstraordinary find before it was cracked open on Friday. Picture: Karleen Minney

The team at Bungaree farm made a remarkable discovery earlier this week.

Could an over-sized 209-gram egg, laid by one of the farm's free-range chooks, be Australia's largest?

Tania Cusack, whose family runs the farm, certainly thinks so.

Mrs Cusack on Friday brought the egg to Canberra where she sells eggs at the EPIC and south side farmers' markets each weekend.

"I just couldn't find anything more than that sized egg. When you look at the average supermarket-sized egg, it's actually four times the size of a large supermarket egg. So there you go," Mrs Cusack said.

Did one of these chickens, roaming the Cusacks' farm, lay Australia's largest egg? Picture: Supplied

Did one of these chickens, roaming the Cusacks' farm, lay Australia's largest egg? Picture: Supplied

Mrs Cusack, who grew up on a chicken farm in the Adelaide Hills, said she knew the egg was big the moment it was brought in from the hens.

"I thought, 'That's a really big egg!' I might have said an F-word, but anyway. We thought that's got to be the biggest egg we've ever had. We won't crack it yet, but there's definitely something moving around inside it. It's almost like there's actually another whole egg inside it," she said before the egg was cracked open.

The chicken who laid the egg has not been located among the thousands on the property, located between Yass, Boorowa and Harden.

In 2015, a chicken laid a 207-gram egg in Mundoolun, south of Brisbane in Queensland.

A backyard chook laid a 121-gram egg in Ballarat last month, thought to be the largest ever found in the regional Victorian city.

The Guinness Book of Records says a 454-gram egg, with a double yolk and double shell, laid by a White Leghorn at Vineland, New Jersey in the United States in February 1956 is the largest known.

Eddy Cusack cracks into the monster-sized egg on Friday. Picture: Karleen Minney

Eddy Cusack cracks into the monster-sized egg on Friday. Picture: Karleen Minney

The Cusacks originally wanted to run a charity auction for the egg, raising money for Rotary, which runs the farmers' markets. But on Friday afternoon its rough and heavy shell began to show signs it was cracking.

Mrs Cusacks' 10-year-old son, Eddy, got the opportunity to crack the egg properly. Once he broke through the tough shell, a perfectly formed second egg was revealed inside.

Both the outer and inner eggs contained a liquid like an already mixed yolk.

The free-range eggs started off as a sideline on the Cusacks' farm, not long after Mrs Cusack went to get some backyard chooks.

"I just went to buy chickens from this guy who was selling. ... When they get to about 18 months old, they slow down in their production. I thought I would just get a few backyard chickens. As it turned out, instead of buying 12 chickens, we bought about 3500 of them," Mrs Cusack said.

Soon the Cusacks had taken over the man's egg business, and now have 5000 chickens which produce the eggs they supply to restaurants and cafes around Canberra. The farm produces more than 24,000 eggs a week, equivalent to about a tonne.

"We grow the wheat here and everything like that, so we thought it was a really good add-on. Of course we had COVID hit, but that turned out into a bit of a frenzy of people buying eggs because everyone was coming to the markets and buying fresh food, and everyone's eating at home and stuff like that," Mrs Cusack told the Sunday Canberra Times.

"So it actually turned out to be a positive for us."