December 17, 2013
Global Study Reveals ‘Efficiency’ Of Livestock And Their Diets
Lee Rannals for redOrbit.com - Your Universe Online
The impact that livestock have on the environment varies 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 on livestock ecosystems.
The most detailed livestock analysis to date shows the variables at play when considering how cows, chickens and pigs impact climate change. The study is considered the most detailed livestock analysis to date, showing vast differences in animal diets and emissions.
Researchers analyzed what cows, sheep, pigs, poultry and other farm animals are eating in different areas of the world. They looked into how efficiently these animals convert that feed into milk, eggs and meat, as well as 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 couple of pounds 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 emissions vary depending on the animals involved and quality of their respective diets.
"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 He0p-;-********-rrero, lead author of the study published in the journal Proceedings of the National Academy of Sciences (PNAS).
The analysis found that of the 59 million tons of beef produced in the world in 2000, the vast majority came from cattle in Latin America, Europe and North America. All of sub-Saharan Africa produced only about 3 million tons of beef total.
Industrial scale production accounts for nearly all of the poultry and pork produced in Europe, North America and China, while small-scale farmers dominate this category in South and Southeast Asia, the Middle East and Africa.
Nearly all of the 1.3 billion tons of grain consumed by livestock each year are fed to farm animals in Europe, North America, Eastern China and Latin America. All of the livestock in sub-Saharan Africa combined eat only 50 million tons of grain each year. The researchers said these animals rely more on grasses and stivers, which are leaf and stalk residues of crops left in the field after harvest.
"This very important research should provide a new foundation for addressing the sustainable development of livestock in a very resource-challenged and hungry world, where, in many areas, livestock can be crucial to food security," Harvard University's William C. Clark, editorial board member of the Sustainability Science section at PNAS, said in a statement.
The scientists also calculated the amount of greenhouse gases livestock are releasing into the atmosphere and to examine emissions by region, animal type and animal product. They modeled only the emissions linked directly to animals.
"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," said Herrero, who earlier this year left International Livestock Research Institute (ILRI) to take up the position of chief research scientist at the Commonwealth Scientific and Industrial Research Organization (CSIRO) in Australia.
The researchers calculated the amount of greenhouse gases livestock are releasing into the atmosphere and examined emissions by region, animal type and animal product. They modeled only the emissions linked directly to animals.
According to the study, South Asia, Latin America, Europe and sub-Saharan Africa have the highest total regional emissions from livestock. Developing worlds account for the most emissions from livestock, including 75 percent of emissions from cattle and other ruminants and 56 percent from poultry and pigs.
Researchers found that cattle are the biggest source of greenhouse emission from livestock around the world. This group of farm animals account for 77 percent of greenhouse emissions from livestock, while pork and poultry account for just 10 percent of emissions.
An important finding from the analysis relates to the amount of feed livestock consume to produce two pounds of protein, which is known as 'feed efficiency.' The study shows that cows, sheep and goats require up to five times more feed to produce two pounds of protein in the form of meat than the same in the form of milk.
"The large differences in efficiencies in the production of different livestock foods warrant considerable attention," the authors wrote in the journal. "Knowing these differences can help us define sustainable and culturally appropriate levels of consumption of milk, meat and eggs."
The researchers said pigs and poultry are more efficient at converting feed into protein than cattle, sheep and goats. They said this is the case regardless of the product involved or where the animals were raised.
"Our data allow us to see more clearly where we can work with livestock keepers to improve animal diets so they can produce more protein with better feed while simultaneously reducing emissions," said Petr Havlik, a research scholar at IIASA and a co-author of the study.