The New Zealand Herald reports changes to welfare rules taking effect tomorrow will increase demand for locally produced ham, pork and bacon.

The new Animal Welfare (Pigs) Code responds to public concern over the mistreatment of pigs. The code will ban sow stalls in pig farming by December 2015. Animal welfare groups lobbied for the code for over 10 years.

The code puts greater restrictions on farrowing crates and sow stalls. About 40 percent of pig farmers still use sow stalls.

"Currently sows on a lot of farms in New Zealand spend their entire lives either in a sow stall or a farrowing crate or a mating stall. They can't turn around for their entire lives, once they've started breeding," Dr Hellstrom said.

The restrictions will lead to higher pork prices, the pork board said the extra costs will total over $20 million which will have to be recovered somewhere. Some pig farmers with smaller operations may be unable to adapt to the new code, forcing them out of the business.

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