The colony cage egg farm where it was filmed, is Northern Eggs in Purua, near Whangarei. The farm can house up to 175,000 chickens.

The Code of Welfare for Layer Hens states: "Every hen must be inspected at least once a day... and dead hens removed from the flock daily."

"These birds are supposed to be checked regularly, and that's obviously not happening," said Marianne Macdonald, SAFE's campaigns manager.

Northern Eggs director Lee McGrath declined to be interviewed, and would not allow Newshub to look inside the sheds where the farm houses its hens.

In a statement, Northern Eggs said: "this activist footage is by no means representative of the care we show our birds."

"It is not uncommon to see birds lacking in feathers at the end of their laying cycle, or for an unwell bird to be missed, despite daily routine checks by multiple staff."

Northern Eggs added: "We consistently meet and exceed the regulatory standards set out and this is reflected in our annual audit results. We prioritise maintaining good health and low mortality across the farm."

Northern Eggs is part of the Independent Egg Producers Co-operative. Its eggs are sold at supermarkets across New Zealand under the Morning Harvest brand.

Colony cages are replacing battery cages, which will become illegal in 2023, but it will be difficult to buy caged eggs come 2025, as supermarkets have promised to stop selling them.

"Labour and the Green Party both made election promises to say they'd ban colony cages. Now it's the Government's year of delivery, and all we've seen is broken promises for animals," said Macdonald.

The Minister of Agriculture, Damien O'Connor, said: "I don't believe there is a need for Government to involve itself currently".

"Egg producers are best placed to decide what systems to use in order to adhere to the code of welfare for layer hens," O'Connor said.

The Ministry for Primary Industries will inspect Northern Eggs as part of its investigation.