McDonald’s, which has 37,000 restaurants worldwide and 14,000 in the U.S., said it has been developing its policy over the past year and a half in consultation with public health leaders, veterinarians and beef producers. The effort came after McDonald’s in 2016 reached its goal to serve U.S. customers only chicken not treated with antibiotics important to human medicine, which prompted both the poultry industry and other restaurants to make changes as well.