DairyGEM 3.2 was available to download from the developer's website when we last checked. We cannot confirm if there is a free download of this software available. DairyGEM relates to Education Tools. This free software is an intellectual property of USDA-ARS. The most popular versions of the tool 3.2, 3.1 and 3.0. We recommend checking the downloaded files with any free antivirus.
From the developer:
The Dairy Gas Emissions Model (DairyGEM) is a tool for estimating ammonia, hydrogen sulfide, and greenhouse gas (GHG) emissions of dairy production systems as influenced by climate and farm management. A dairy production system generally represents the processes used on a given farm, but the full system may extend beyond the farm boundaries.
You may want to check out more software, such as Adding Machine, gitoolbox or PC-Display, which might be similar to DairyGEM.