Global Livestock Environmental Assessment Model (GLEAM)

The model uses a classification of farming systems based on the feed use and agro-ecological conditions. GLEAM distinguishes three farming systems for cattle (grazing, mixed and feedlot), two for other ruminant species (grazing and mixed), three for pigs (backyard, intermediate and industrial) and three for chicken (backyard, layers and broilers). Three agro-ecological zones are considered: temperate -which includes temperate regions and tropical highlands, arid -including arid and semi-arid tropics and subtropics, and humid -comprising humid and sub-humid tropics. Overall, this amounts to over 9,000 discrete supply chains, defined as unique combinations of commodity, country, farming system and climatic conditions.