Kathleen McLaughlin, senior vice president of Wal-Mart's sustainability division, told The Associated Press in a phone interview Thursday that the retailer is not putting deadlines on suppliers and the steps aren't mandatory. The guidelines, which apply not only to suppliers to Wal-Mart stores but also to Sam's Club, are part of the company's pledge to make its food system more eco-friendly and improve food safety. Wal-Mart is facing pressure from critics like Mercy for Animals, a national animal rights group that has conducted six investigations over the past few years on farms that supply pork to Wal-Mart. In July 2014, Wal-Mart announced it was requiring its fresh pork suppliers to have video monitoring for sow farms and would be subject to unannounced animal welfare video audits by a third party. Gary Mickelson, a spokesman at Tyson Foods Inc., based in Springdale, Arkansas, told The Associated Press that it was making "significant progress" in the areas of antibiotic use and animal well-being.