New rules requiring pig farmers in the European Union to do away with gestation crates have some worried that pork production from the world’s second-largest producer may drop. Many farmers charge that moving away from using the crates will cost farmers a lot and some may opt to go out of business instead.

Beginning Jan. 1, farmers in the E.U.’s 27 nations will be required to use open pens, instead of the highly confining crates that are currently common. That may decrease Europe’s pork output and has some worried about higher global pork prices, according to Bloomberg’s Whitney McFerron.

Pork output in Europe, the biggest shipper after the United States, may drop as much as 10 percent after the ruling goes into effect, because some farmers aren't prepared to make the change, Britain's Agriculture and Horticulture Development Board said.

The use of gestation crates in U.S. pork production has also recently been under fire from animal rights activists, and big buyers like McDonald’s and Burger King have asked their producers to quit the practice. Some pork interest and lobbying groups, though, like the E.U.’s Copa-Cogeca, say changing the way pork is produced could have huge impacts on the price of pork for consumers.

A 5 percent decline in E.U. pork production would equate to about a 10 percent increase in consumer prices, said Pekka Pesonen, the secretary-general of Copa-Cogeca in Brussels.

The E.U. is the world’s second-largest pork producer, behind China, and currently produces twice the amount of pork as the United States.