These are going to be defined in the IPCC 2006 assessment:

    1. Stall- animal are confined to a small area (i.e. tethered, pen, barn) with the result that they expend very little or no energy to acquire feed. 
    2. Pasture- animals are confined in areas with sufficient forage requiring modest energy expense to acquire feed
    3. Grazing large areas- animals graze in open range land or hilly terrain and expend significant energy to acquire feed.