The high global demand for energy led to an increasing production and trade of bio-fuel, especially liquid fuels for transportation, in order to substitute fossil energy sources, to enhance energy security and to respond to greenhouse gas emissions. The increase in bio-ethanol industry has created a need for alternative to corn for ruminants. In the other side there is an increase availability and promote favorable pricing for glycerol, a primary co-product material. The objective of this study was to investigate the effect of partial replacing of corn by glycerol in diets fed to ruminant animals.