Livestock research finds cattle are the top emitters
In the most detailed livestock analysis so far, researchers from Europe, Africa and Australia have found greenhouse gas emissions vary widely depending on the type of animal, its diet and where it lives.
The research covers 28 regions, eight different production systems, four types of animal (cattle, small ruminants, pigs and poultry) and three products (milk, meat and eggs). Findings were published on December 16 in an early edition of the Proceedings of the National Academy of Sciences (PNAS).
Researchers from the International Livestock Research Institute (ILRI) collaborated with the Commonwealth Scientific and Industrial Research Organisation (CSIRO), to assess the contribution of livestock to global land use and greenhouse gas emissions.
Their analysis looks at the feed being given to livestock animals in different parts of the world, and how efficiently they convert this into meat, eggs and milk. It provides information on biomass use, feed efficiency, excretion, greenhouse gas emissions and production.
According to the research, titled “Global livestock systems: biomass use production, feed efficiencies and greenhouse gas emissions”, cattle are the largest source of greenhouse gas emissions, while emissions per unit of product are lowest for chicken meat, eggs and milk.
Emissions, however, were found to vary significantly according to the quality of the animal's diet, the type of product it produces and where it lives.
The largest emissions were found to come from production systems where the animals had a poorer diet, for example arid regions in sub-Saharan Africa, south and east Asia.
Animals in many parts of the developing world were found to require far more food to produce one kilo of protein, compared with animals in wealthier countries.
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