Dr. Alexander N. Hristov is a Distinguished Professor of Dairy Nutrition in the Department of Animal Science at The Pennsylvania State University and is a member of several professional societies and of the Feed Composition Committee of the National Animal Nutrition Program. He has a B.S. from the Higher Institute of Zooengineering and Veterinary Medicine, Stara Zagora, Bulgaria, and a Ph.D. in Animal Nutrition from the Bulgarian Academy of Agricultural Sciences. Hristov has worked as a research scientist at the Institute of Animal Sciences, Kostinbrod, Bulgaria, the USDA-ARS Dairy Forage Research Center in Madison, WI, and the Ag Canada Research Center in Lethbridge, AB. He was on the faculty at the Department of Animal and Veterinary Science, University of Idaho from 1999 to 2008 and is at Penn State since 2008. Hristov's main research interests are in the areas of mitigation of nutrient losses and gaseous emissions from dairy operations and protein and amino acid nutrition of dairy cattle. He initiated and led the development of the world's first Dairy MOOC (Massive Open Online Course) with a current enrollment of over 57,000 (https://www.coursera.org/learn/dairy-production). Hristov has given over 110 invited presentations and published over 220 books, book chapters, and peer-reviewed journal articles with over 20,000 citations and all-time Google Scholar h-index of 78 and i10-index of 195.