Speaking from a tripod earlier, Ms Sims said she was "willing to put my life on the line'' to bring an end to cages for battery hens.
"We have placed ourselves in this potentially very dangerous position and are prepared to risk our lives if it helps to prohibit the use of all cruel cage systems in New Zealand. This should serve as a strong warning to Mainland Poultry that we are escalating our efforts and remind consumers not to buy Farmer Brown eggs, which are Mainland's cage-produced range,'' she said.
Workers on foot got into the building using another entrance, said Mainland Poultry general manager of sales and marketing Hamish Sutherland, who described the protest as a "stunt''.
Mainland Poultry has been trialling 'colony cages' to replace existing battery cages following a review of the Code of Welfare for Layer Hens but Ms Sims said that wasn't enough.
"A cage is still a cage. it's still factory farming and it's not good enough.''
Mr Sutherland said the colony cages had been trialled in the UK and EU and were a positive step forward for animal welfare, as they were 30 per cent larger and had perch and nesting areas and a scratch pad.
Free-range only eggs was not practical, he said.
"If you remove this cheaper production method out of the system then you're potentially going to price eggs out of the diet of many New Zealanders.''