The world’s largest retail chain will transition to cage-free eggs by 2025. Bloomberg reports Wal-Mart and its Sam’s Club warehouse chain will require that its egg suppliers adopt United Egg Producers rules or an equivalent set of standards for cage-free housing. The company says compliance will be checked annually by a third party. Wal-Mart sells more groceries than any other company in the country. The new guidelines will apply to the retailer’s more than 5,000 stores in the United States. The move by Wal-Mart puts more pressure on the egg industry which is facing a costly transition to cage-free housing. The United Egg Producers group says only six percent of U.S. hens are currently raised without cages.