This chapter provides guidance on methods to estimate emissions of methane from Enteric Fermentation in livestock, and methane and nitrous oxide emissions from Manure Management. Carbon dioxide(CO2)emissions from livestock are not estimated because annual net CO2emissions are assumed to be zero ?the CO2photosynthesized by plants is returned to the atmosphere as respired CO2. A portion of the C is returned as methane (CH4)and for this reason CH4 requires separate consideration