A study, published in an early edition of the Proceedings of the National Academy of Sciences (PNAS), is the newest comprehensive assessment assembled of what cows, sheep, pigs, poultry and other farm animals are eating in different parts of the world; how efficiently they convert that feed into milk, eggs and meat; and the amount of greenhouse gases they produce.
The resources required to raise livestock and the impacts of farm animals on environments vary dramatically depending on the animal, the type of food it provides, the kind of feed it consumes and where it lives, according to a new study that offers the most detailed portrait to date of ‘livestock ecosystems’ in different parts of the world.
The study, produced by scientists at the International Livestock Research Institute (ILRI), the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the International Institute for Applied Systems Analysis (IIASA), shows that animals in many parts of the developing world require far more food to produce a kilo of protein than animals in wealthy countries. It also shows that pork and poultry are being produced far more efficiently than milk and beef, and greenhouse gas emissions vary widely depending on the animal involved and the quality of its diet.
The data for livestock production and diets for example reveal sharp contrasts in overall livestock production and diets. Of the 59 million tons of beef produced in the world in 2000, the vast majority came from cattle in Latin America, Europe and North America. All of sub-Saharan Africa produced only about 3 million tons of beef.
Highly intensive industrial-scale production accounts for almost all of the poultry and pork produced in Europe, North America and China. In stark contrast, between 40 to 70 per cent of all poultry and pork production in South and Southeast Asia, the Middle East and Africa is produced by small-scale farmers.
Scientists also sought to calculate the amount of greenhouse gases livestock are releasing into the atmosphere and to examine emissions by region, animal type and animal product. They modelled only the emissions linked directly to animals—the gases released through their digestion and manure production.
South Asia, Latin America, Europe and sub-Saharan Africa have the highest total regional emissions from livestock. Between the developed and developing worlds, the developing world accounts for the most emissions from livestock, including 75% of emissions from cattle and other ruminants and 56% from poultry and pigs.