Kerry Mulqueen, senior executive technical officer at the The Egg Producers Federation NZ, said factors such as feed and weather were unlikely to affect the size of the hen's eggs.
"It's more to do with the age of the hen. The older they get the bigger the eggs," he said.
But then there's the situation where the eggs are double-yolkers - then it is simply because there is a "bigger mass" for the albumin (outer layer or egg white) to cover.
Despite hens being genetically predisposed to producing single-yolked eggs, sometimes younger hens can have a few double-yolkers, before returning to single-yoked eggs.
"Something has upset the timing of the release," he said. "But then it comes back to normal process.
"I wouldn't expect it [Henrietta's large-egg laying] to keep on going - but it is a biological machine so we can't always say," he said.
Although Henrietta's eggs are big for a chicken, the Guinness Book of World Records won't be making any additions with her exploits.
The "largest egg from a bird" is still the work of a Swedish ostrich that laid a five-pounder (2.2kg) in 2008.
