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.
A comprehensive global assessment has been assembled on the diet of cows, sheep, pigs, poultry and other farm animals. In particular, the study looked at how efficiently they convert feed into milk, eggs and meat, while also looking at the amount of greenhouse gases they produce.
The study 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.
Read more at CSIRO