WASHINGTON, March 5, 2014 – Livestock producers can boost profitability and address climate change by mixing systems to include higher quality feed and grass, rather than a pure grass-based system alone, according to research published in the Proceedings of the National Academy of Sciences.
A global team of scientists representing Austria, Africa, Australia, the Caribbean, Europe and the United States says that cows, sheep, and goats grow more quickly and produce more milk when they eat energy-rich diets that include grain supplements or improved forages. This means that more livestock can be raised on less land, and with fewer emissions per pound of meat or milk produced.
“There is a lot of discussion about reduction of meat in the diets as a way to reduce emissions,” says Petr Havlík, a researcher with the International Institute for Applied Systems Analysis (IIASA) in Austria, who led the study. “But our results show that targeting the production side of agriculture is a much more efficient way to reduce greenhouse gas emissions.”
Scientists have in the past decade determined that livestock production is responsible for about 12 percent of human-related greenhouse gas emissions (GHGs), mostly caused by changes in land use and deforestation undertaken to expand grazing areas, as well as methane released by the animals themselves. A lesser amount of emissions come from manure management and feed production, scientists say.
Livestock provides a third of the protein in human diets. As the middle class continues to grow in developing nations, the demand for meat and dairy protein is expected to rise and, as a result, emissions are expected to increase.
Some 30 percent of global land area is used to raise livestock, and between 1980 and 2000, an estimated 80 percent of agricultural land expansion came in tropical areas, including forestland. Much of the new space was used to raise cattle, sheep and goats, as well as grow corn and soybeans for animal feed.
But the new research shows that supplementing grazing with high quality feeds could lead to a 23 percent reduction of emissions from land-use change in the next two decades.
The new study projects that the increasing cost of land and continued yield increases in the crop sector will lead to global shifts to richer animal diets, which are efficient in not only reducing GHGs, but also in profit maximization and food production.
Citing a moderate price of $10 per ton of carbon dioxide equivalent, the study says livestock system transitions within a given region, together with international relocation of production to regions with the most efficient livestock systems, could also reduce the total emissions from agriculture and land use change by 25 percent, with most of the savings coming from avoided land use change.
“From the livestock sector perspective, limiting land-use change seems the cheapest option both in terms of the economic cost and in terms of impact on food availability,” Havlík says.
The study just published adds to previous work by the group that produced a detailed database highlighting the differences in the efficiency and greenhouse gas emissions of different livestock production systems. The study examines the economic potential for a transition to more efficient systems as a mitigation measure and offers policies that would be the most effective for cutting greenhouse gas emissions, all while maintaining food availability.
Havlík and his colleagues say that improved diets for animals would be lower in cellulose and richer in energy, and that means lower methane emissions from flatulent animals.
The United Nations Food and Agriculture Organization says livestock production accounts for 37 percent of the methane produced through human activity. Over a 20-year time frame, methane is 70 times more powerful than the oft-cited GHG, carbon dioxide.
Methane, scientists say, also has a much shorter half-life – eight years – compared to the 100 years half-life of carbon dioxide. As a result, any reduction in methane has a much more immediate impact – a critical attribute given what research shows is the speed with which major climate disruptions have been occurring over the past several decades, including extensive floods and widespread drought.
The IIASA study also introduces a new metric for measuring the costs of climate measures for agricultural systems. The so-called Total Abatement Calorie Cost (TACC) complements the pure economic metric known as “marginal abatement cost,” while also capturing the impacts of mitigation measures on food security.
Mario Herrero, a co-author of the study, says that applying current metrics could lead to mitigation, but also food insecurity in developing countries, because it ignores the social cost of policies that focus just on greenhouse gas abatement.
"So we developed a new metric which tells you how consumption would be affected as a result of mitigating greenhouse gas emissions,” she said.
Changing livestock production systems remains a challenge, the researchers say, noting that policies that provide education and market access are the keys for enabling change. In addition, they say safeguards are needed to insure that the growing intensity in production cited by their study does not lead to environmental damage or reduce animal well-being.
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