Dr. Danilo Millen is an Animal Scientist, with a Master's and PhD degrees in Animal Sciences. He is an associate professor of the Animal Sciences Department at Sao Paulo State University, UNESP. His research is based on rumen metabolism and feedlot cattle nutrition. During the past decade he has been working on evaluations of several feed additives, manipulation of rumen fermentation, protocols of adaptation for Nellore cattle and rumen health. Dr. Mario De Beni Arrigoni is an Animal Scientist with a Master's and PhD degrees in Animal Sciences. He is an associate professor of the Department of Breeding and Animal Nutrition at Sao Paulo State University, UNESP. For the past 25yrs he has been working on ruminant nutrition in particular with beef cattle, focusing on calf-feds, carcass ultrasound measurements, beef quality, and lately on manipulation of rumen fermentation and use of carbon isotopes in beef cattle studies.