Methane from enteric fermentation is a large component of livestock related greenhouse gas emissions. Typically, methane emissions from enteric fermentation represent on average 6% of dietary gross energy, but this varies greatly with diet (Johnson and Johnson, 1995). In order to mitigate methane emissions in a way that is acceptable for both the environment and animal welfare, it is important to quantify the effects of different diets on methane emissions. The objective of the current study was to determine the effect of different silages on methane emissions from dairy cows.