Confused about negative PPDs? Expert explains what that number means Despite negative producer price differentials plaguing the dairy industry in 2020, many people are still confused on what a PPD is and how it affects their milk check. Marin Bozic, assistant professor of dairy food marketing and economics at the University of Minnesota, was a guest on Dairy Business Association's Dairy Stream podcast and took a stab at explaining the meaning of federal milk marketing orders and PPDs and what to expect of them this year. FMMOs, which are region-specific, are a collective bargaining tool that ...