Walmart Is the Latest Retailer to Make a Cage-Free Egg Vow by John Kell @FortuneMagazine April 5, 2016, 6:37 PM EST E-mail Tweet Facebook Linkedin Share icons Walmart, America’s biggest food seller, is committing to fully source cage-free eggs, scoring a huge win for supporters of animal rights and sustainability. The world’s biggest retailer said that U.S. Walmart and Sam’s Club stores would transition to a 100% cage-free egg supply by 2025–a timeline that matched recent commitments from other big grocers including Albertsons, Kroger kr and Supervalu svu . “Our commitment to transition to a cage-free egg supply chain recognizes that expectation and represents another step we are taking to improve transparency for food we sell in our U.S. stores and clubs,” said Kathleen McLaughlin, chief sustainability officer at Walmart wmt . Walmart, which has sold cage free eggs at the company’s U.S. stores since 2001, said it would meet the 2025 goal based on “available supply, affordability and customer demand.” The retailer also outlined specific requirements it intended to adopt, including requirements for nests and perches and a minimum space of 1.0 square foot per hen. Restaurants, food makers, and egg suppliers have in recent months announced multi-year commitments to exclusively use cage-free eggs, a policy shift animal welfare advocates say is important because of the otherwise pain caused to chickens kept in cramped cages. Other grocers that have joined the movement have included Trader Joe’s, Safeway, and Sprouts Farmers Market sfm . But Walmart is particularly important as it accounts for 25% of all food sold in the U.S. Wayne Pacelle, president and CEO of The Humane Society of the U.S., said in a statement that the group’s advocacy on the issue turned a corner in September when McDonald’s mcd announced its cage-free policy. “But today, that debate ends, and the trajectory is clear,” Pacelle said. “The era of confining hens in cages in America’s food system is officially sunsetting.” Walmart had previously found itself the target of the Humane Society, which in late 2009 submitted a shareholder resolution with the retailer that called on the company to disclose how it planned to shift to cage-free eggs. Walmart later confirmed that all of the company’s private label eggs under “Great Value” were cage free–leading the advocacy group to withdraw its resolution.