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Researchers — from the International Livestock Research Institute, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the International Institute for Applied Systems Analysis — say policymakers need comprehensive data on livestock production systems and their environmental impacts globally to enable them design effective interventions.
The researchers therefore identified 8 different types of livestock systems in 28 geographic regions and estimated number of cattle, small ruminants, pigs and poultry for each system for the year 2000. They also estimated greenhouse gas emissions produced by the livestock in that year for each region, system and species of animals.
“The study shows that the quality of an animal’s diet makes a major difference in both feed efficiency (ability to convert food to protein) and emission intensity.”
Mario Herrero, Commonwealth Scientific and Industrial Research Organisation (CSIRO)
“This information will allow the global-change research community in enhancing our understanding of the sustainability of livestock systems and their role in food security, livelihoods and environmental sustainability,” the researchers write in the Proceedings of the National Academy of Sciences last month (16 December).
The study shows that the quality of feed consumed by livestock contributes greatly to the amounts of greenhouse gases that they emit, with African cattle leading in the intensity of the gases released.
“Cattle scrounging for food in the arid lands of Ethiopia, Somalia and Sudan can, in the worst cases, release the equivalent of 1,000 kilos of carbon for every kilo of protein they produce. Comparatively, in many parts of the United States and Europe, the emission intensity is around 10 kilos of carbon for a kilo of protein,” says a brief report highlighting the study.
African cattle thrive on low-quality rangeland grass or crop residue of low nutritional value, thus consuming huge amounts to produce meat or milk,and emitting large quantities of carbon into the environment, according to the report’s lead author, Mario Herrero, a chief research scientist with Australia-based CSIRO.
“The study shows that the quality of an animal’s diet makes a major difference in both feed efficiency (ability to convert food to protein) and emission intensity,” Herrero adds.
The report shows that cattle are the biggest emitters of greenhouse gases worldwide, producing 77 percent of emissions whereas pork and poultry release only 10 percent, noting that cattle and other ruminants in Latin America, South Asia and Africa alone produce 75 percent of the world’s greenhouse gases.
In terms of feed, the study notes that livestock across the world consume about 1.3 billion tons of grain annually, with African animals consuming about 50 million tons of that, relying more on grasses and crop leftovers after harvest.
Mariana Rufino, a Kenya-based senior climate scientist at the Center for International Forestry Research, says improved feeds would greatly raise production while cutting emissions.
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This article has been produced by SciDev.Net's Sub-Saharan Africa desk.
PNAS doi: 10.1073/pnas.1308149110 (2013)