Warning: This story contains graphic content that may upset some readers
A former Northern Eggs worker has shared claims of animal cruelty at the Whangārei producer with animal rights organisation SAFE.
Photos shared by the source in May this year show "hens left to rot in cages", the organisation stated in a press release.
The images viewed by 1News show hens standing on top of dead hens in battery cages - also referred to as conventional cages - and in colony cages, which have slightly larger minimum space requirements for hens.
Blood is seen beneath eggs near a dead hen in one photo, and in others, dead hens are missing their feathers in some areas.
The layer hens code of welfare states dead hens must be removed daily.
In a statement, Northern Eggs said hen deaths are monitored and recorded every day.
"Whilst it is confronting to see images of any dead animal, mortality does occur in livestock operations," the producer stated.
"We strongly refute the allegations of the activists. We believe these historic photos were taken by a disgruntled employee who no longer works for our company."
The former worker, who wished to remain anonymous, told SAFE he saw birds being kicked down the aisles of sheds and that it was "not uncommon" to see birds with infections as well as broken wings and legs.
"Guys smashing birds against bins to break the necks... It’s not unusual to see guys swinging the birds around by their necks until their heads come off completely," the source said in a SAFE podcast episode.
"There were times when guys were caught just shoving birds in the bottom of the wheelie bin and then killing birds and dropping them on top so the ones on the bottom ended up suffocating and being crushed to death."
The former worker said when they reported these acts and hen injuries to the manager, the response was "oh well" or that management would talk to the worker involved "next time".
"The attitude of the manager was pretty much out of sight, out of mind as long as paperwork was done."
Northern Eggs has full confidence in its welfare standards, manager Tracy Martyn said in a response.
"We are constantly reviewing ways to improve our operations, so when a staff member is not performing to the standards required, extra training is provided or they choose to leave the company," she said.
"We are frustrated that the animal activist organisation, SAFE, continues to circulate a number of images of dead birds from our farm prior to May this year."
Northern Eggs said animal welfare was its "top priority" and supermarkets have been invited to inspect the farm.
The business is part of an egg producers cooperative that sells eggs under the brand, Morning Harvest.
Independent auditors have also been commissioned by the business to conduct a welfare audit to "further verify the integrity of our operation", the producer stated.
Following allegations being raised about the practices of Northern Eggs in late 2019 and in May this year, the Ministry for Primary Industries conducted two unannounced welfare inspections.
"We found no evidence of breaches of the Animal Welfare Act," MPI compliance director Gary Orr said in a response.
"It is incorrect to suggest that MPI does not hold people to account."
Orr said when evidence of offending is found, the Government agency will often prosecute or issue infringement notices.
The public has been urged to contact MPI if they have information about potential animal welfare breaches.
SAFE is calling for all caged hen farming to be banned in New Zealand, following similar moves from several European countries and nine states in the United States.
The organisation says colony cages, which must be used with a minimum of 750cm2 per hen, are in breach of the Animal Welfare Act, which states animals must be able to display normal behaviours.
"The fact remains that colony cages are just as cruel as the battery cages they replaced," SAFE campaigns manager Jessica Chambers said in a press release.
"Hens are living in truly harrowing and disgusting conditions, and yet MPI has not held them accountable."
Battery cages are being phased out in New Zealand, with a total ban set to be in place by the end of next year.
SAFE claims a recent Colmar Brunton poll found 76 per cent of Kiwis opposed the caging of hens.
The Egg Producers Federation of New Zealand says Kiwis consume 226 eggs per person annually and that it is one of the highest rates globally.