Restaurants, butcheries and supermarkets yesterday said shocked customers were enquiring about the source of their pork after a television programme featured pigs kept in cramped intensive-farming crates.

Suppliers and free-range advocates believed customers' concerns would spur moves towards paddock-reared labelling for pork products, reports Stuff.co.nz.

However, Pork Industry Board chief executive Sam McIvor said the board did not plan to introduce free-range branding.

Pork prices would rise by $2 a kilogram if sow stalls were immediately banned because change required investment, McIvor said.

The board was committed to improving welfare and housing for pigs, he said.

SPCA national chief executive Robyn Kippenberger said the board had blocked free-range labelling for years to protect the country's biggest pork producers, who were intensive farmers.

"Now they are greeted by a shocked public; they are the authors of their own misfortune," she said.

Three years ago, the SPCA approved a pig-friendly farmer auditing scheme, developed by the Freedom Farms brand.

It had been largely ignored by the board, she said.

Freedom Farms co-founder Gregor Fyfe said seven piggeries produced pork under the brand, which banned the use of stalls and crates.

The Sunday programme had spurred enormous interest in Freedom Farms' products, he said.

"People are flying into worry mode and we have had a huge number of calls from supermarkets," he said.

Freedom Farms' products were about 20 per cent more expensive than commodity-marketed meat.

Consumers could create the market by demanding free-range pork from their butcher and supermarket, Mr Fyfe said.

Steve Sterne, who co-owns New Zealand's largest piggery, Patoa Farms, in Hawarden, said the sow-stall concern had played to the advantage of farmers, like himself, who did not cage pigs.

Claims pork would rise by $2 a kilogram if stalls were banned were baseless, as the majority of farmers were stall-free and still ran an economic business in the commodity meat market.

"The big problem is the lack of regulation on cheap imported pork, which supplies 40 per cent of consumption," Mr Sterne said.

Smallgoods producer Heller Tasty plans to only use stall-free meat in its premium products.

Managing director Nick Harris said it was investigating imported pork products and conditions and practices on all its producer farms.

Foodstuffs New Zealand retail operations general manager Allan Malcolmson said strong customer demand would drive free-range pork supply.

Food and beverage manager Yolande Strydom, of Rydges Christchurch, said the hotel's organic pork meals were in demand.

By 3pm yesterday, over 60 per cent, or 2581, of the 4240 respondents to an online Stuff Media poll said they would look for paddock-reared pork.