Dairy cows (IMAGE) Penn State Caption This 10-week study involved 48 Holstein cows at the Penn State Dairy Teaching and Research Center. Some were fed rations supplemented with an enzyme preparation extracted from a mixed fungal culture, and researchers then evaluated the cows’ lactational performance, metabolism and digestion. Credit Penn State Usage Restrictions No restrictions. License Public Domain 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.