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 from researchers in Nairobi, Kenya. The researchers claim their analysis represents the most detailed portrait to date of "livestock ecosystems" in different parts of the world.

The study, published on Tuesday, 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 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.

"There's been a lot of research focused on the challenges livestock present at the global level, but if the problems are global, the solutions are almost all local and very situation-specific," said Mario Herrero, lead author of the study, who formerly worked at ILRI.

"Our goal is to provide the data needed so that the debate over the role of livestock in our diets and our environments and the search for solutions to the challenges they present can be informed by the vastly different ways people around the world raise animals," Herrero added.

For the last four years, Herrero has been working with scientists at ILRI and the IIASA in Austria to examine livestock impacts beyond what they view as broad and incomplete representations of the livestock sector. Scientists working on the research said the new data fill a critical gap in research on the interactions between livestock and natural resources, and how this differs by global region.