Ministry of Agriculture and Forestry investigators say a piggery belonging to a former pork industry board chairman is not breaking any animal welfare laws.
MAF investigations manager Greg Reid told Newstalk ZB the ministry could only take action if specific animals were suffering unnecessarily or if the pigs had untreated diseases.
He expected the case to trigger a review of regulations for operating pig farms.
The farm had also been investigated three years ago, and cleared of any wrong-doing.
Later today, National Animal Welfare Advisory Committee members would discuss
the future of sow crates, used in pig farms .
Animal welfare activists have criticised the use of farrowing stalls for pregnant pigs, with an animal rights group raiding a farm belonging to former New Zealand Pork Industry Board chairman Colin Kay.
TVNZ's Sunday programme aired footage by animal welfare organisation Open Rescue, who were accompanied by comedian Mike King during a break-in at Mr Kay's Levin pig farm.
Mr Kay said activists had stirred the pigs up, and he was considering legal action against the raiders.
"I don't know what those people were doing in there [to provoke the pigs], they don't normally behave that way," he told Radio New Zealand.
Mr King, who has appeared in numerous pork industry board advertising campaigns, said he felt deeply ashamed of his role in promoting that type of farming.
The pigs were unable to move and obviously in distress, chewing at the cage bars and frothing, he said.
The comedian and former pork industry poster-boy became involved in the plight of farmed pigs after animal welfare advocates sent him material detailing conditions in the farms.
Meanwhile, a major bacon supplier, Hellers Tasty Ltd, has said the example shown in the media in recent days was not representative of the industry.
"But we are checking conditions and pig raising practices on all farms from which we source product," managing director Nick Harris said.
The Green Party said the programme had "lifted the petticoats" on the pork industry.
Green MP and animal welfare spokesperson Sue Kedgley said she planned to take a cross party group of MPs to visit some intensive pig farms.
She said Agriculture Minister David Carter "has a duty, as minister of agriculture, to learn about the reality of pig farming in New Zealand".
At his post cabinet press conference yesterday, Prime Minister John Key said he found the television footage of intensive pig farming "very, very disturbing".
The New Zealand Pork Industry said the pork industry was phasing out long-term use of sow stalls and that the programme did not represent the pork industry as a whole.
The pork industry's board had postponed the annual Bacon of the Year awards in response to the programme.
NZPA