OTTAWA -- A national group of farmers, government and animal welfare advocates has drafted a new policy that calls for limits to the controversial practice of confining pregnant pigs in tiny stalls.

The National Farm Animal Care Council has released a draft of its Code of Practice for the Care and Handling of Pigs that would require mated female pigs be housed in groups.

The proposed policy would be phased in between now and July 1, 2024.

Exceptions would be permitted for up to several weeks after the last breeding because the document notes that sows are inherently aggressive.

New or rebuilt barns would have to follow the new standard starting July 1, 2014.

Critics say the stalls prevent the pigs from even turning around, but some industry representatives have defended their use.

The Retail Council of Canada announced in April that eight of the largest Canadian supermarket chains will move away from the confinement of pigs in their supply systems over the next nine years.

A public comment period give producers, consumers and others with an interest in the welfare of pigs until August 3 to view the draft and provide input to a final version.

"The requirements and recommended practices in this document represent a challenging balance between animal welfare and the abilities of producers to affect change in an economically viable way," the introduction to the draft states.

"As the code development process involved representatives with diverse interests, not all parties fully agree with every requirement and recommendation. However, all members agree that this document represents the best achievable balance."

A Canadian campaigner with Humane Society International welcomed the news, although she said her organization still has a problem with the continued confinement of some pregnant pigs, as well as the long phase-out period for tiny stalls, known as gestation crates.

"While there is still significant room for improvement in the Code of Practice, we look forward to engaging with the public and with NFACC throughout the consultation period to address the most concerning issues," Sayara Thurston said in a news release.

The draft states that any individual pig stalls built after July 1, 2014 must be large enough for the animals to stand or rest without simultaneously touching both sides or the top of the stall, as well as lie down without their udders protruding into adjacent stalls.

Rick Bergmann, a vice-chairman with Manitoba Pork producers, said last month that the debate over gestation stalls was being argued on social media by people who knew very little about raising hogs.

He said he and his wife began hog farming in the mid-1980s and housed sows in pens, not outside as both of their fathers did. He said it protected them from other aggressive sows and is safer for employees and it ensures sows get the right amount of feed.

The council says that when the Code of Practice is complete, it will guide the review and update of the Canadian Pork Council's Animal Care Assessment program.

The final pig Code of Practice is expected to be released by the end of 2013.