The fire at an Orini egg laying farm in Waikato killed 50,000 chickens, not the 75,000 the business had announced in an earlier statement.

The fire started at 7.20am on Monday at a Zeagold Nutrition farm in Orini and took hold in two of the 12 barn layer sheds.

"We have a specialist avian vet at Orini currently assessing and caring for the birds in the remaining sheds," says chief executive John McKay.

"His initial report is that the birds seem to be in good health. They will continue to be closely monitored in the coming days."

He says two out of 12 sheds on site have been destroyed.

Engineers and electricians have been called in to restore power, water and feed to all the remaining sheds.

He expected the onsite packing facility to be operational from Sunday evening to ensure all the eggs unaffected by the fire can be packed and delivered to customers.

It would take time to rebuild the sheds and restore flock numbers. In the meantime the business will be "working hard to continue to supply eggs and get back to full capacity as soon as possible".

"I know New Zealanders will be worried about what this means when eggs are in short supply. The reality is the losses at Orini, represent only 1.4 per cent of the layer hen population nationally so while it's a tragic loss it won't have a significant impact on egg supply."

Earlier on Monday, McKay said all 12 staff members on site were safe and unharmed.

Ten emergency vehicles were at the site and managed to contain the fire. Some units were remaining on site to dampen down any hot spots, McKay said.

"We would like to thank Fire and Emergency NZ for their quick response and great efforts."

The Orini egg laying farm has been running for almost two years now and has high standards of welfare for its chickens, McKay says.

The cause of the fire is yet to be determined and at this stage the focus is on the welfare of the company's hens which survived.

The business is "devastated" to lose so many chickens, he says.

The country has been experiencing a nationwide shortage of eggs this year.

It's the end result of a few different things: a 10-year transition away from battery cages; the decision by the big supermarket chains to go completely cage-free; and supply chain issues borne of the pandemic and the war in Ukraine.

At the moment, New Zealand's chicken population is about 400,000 short to meet demand.

Egg Producers Federation executive director Michael Brooks says, although the Waikato fire certainly added to the egg shortage in New Zealand, consumers should not be affected.

The country has more than three million birds and the impact of the incident would not reach the wider industry, he says.

Consumer NZ agrees that Monday morning's fire should not cause egg prices to rise.

Consumer NZ chief executive Jon Duffy says while the fire put more pressure on the industry, prices should not change.

The hens affected represented a small percentage of the total number of chickens in New Zealand, he says.

-RNZ.