OAK BROOK, Ill. — McDonald’s Corp. will now require its suppliers to follow an updated set of guidelines for raising and slaughtering chickens used for its popular signature menu products, such as McNuggets and McChicken sandwiches.

As reported by Reuters, McDonald’s suppliers, including Tyson Foods Inc. and Cargill Inc., must comply with new rules for humane treatment of chickens. The revamped policies dictate the amount and brightness of light in chicken houses, and outline how the birds must have access to perches that promote natural behavior, in addition to other initiatives. All suppliers must comply with the new parameters by 2024.

However, some animal activists said the chain’s new mandates fall short of recent animal-welfare commitments made by other restaurants, including Burger King and sandwich chain Subway, and failed to address their primary concern about chicken production: how quickly birds are bred to grow to large sizes. However, McDonald’s has pledged to conduct trials with its suppliers to measure the well-being of the chickens.

“I think it’s one of the most comprehensive programs that I’ve seen for chickens,” livestock researcher Temple Grandin told Reuters. Grandin pioneered humane slaughterhouse practices and works with McDonald‘s.

McDonald’s latest requirements join other commitments recently made by top convenience chains, including Pennsylvania-based c-store retailers Wawa and Sheetz, to address concerns about animal welfare and animal health. McDonald’s, for example, has stopped buying chicken meat for U.S. restaurants from birds raised with antibiotics and announced that it would shift to using cage-free eggs in the U.S and Canada.

McDonald‘s said it will not raise menu prices as a result of its new standards.

“While this might not be a direct impact on sales at McDonald’s, it might help certain segments of our customer base make purchasing decisions that they might not have otherwise made,” Bruce Feinberg, a senior director for McDonald’s, said to Reuters.

The move by McDonald’s is said to be supported by both Tyson and Cargill; however, animal-welfare groups said the chain failed by not committing to buying meat from breeds that grow slowly enough to protect chickens’ health. Birds bred to grow more quickly can suffer organ failure and struggle to walk because they become too heavy, they said.

“McDonald’s at this point is allowing the industry to continue in this inhumane direction,” said Josh Balk, a vice president for The Humane Society.