Dairy Map (IMAGE) Penn State Caption Map of the United States Federal Milk Marketing Orders. Penn State researchers analyzed 15 years of records showing the yield and composition of milk production across the country in their research that revealed the annual rhythm that governs dairy cows' output. Credit US Department of Agriculture Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.