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Image copyright Getty Images Image caption Cattle need 28 times more land than other livestock, according to a new study 
  
 A new study suggests that the production of beef is around 10 times more damaging to the environment than any other form of livestock. 
  
 Scientists measured the environment inputs required to produce the main US sources of protein. 
  
 Beef cattle need 28 times more land and 11 times more irrigation water than pork, poultry, eggs or dairy. 
  
 The research has been published in the Proceedings of the National Academy of Sciences. 
  
 While it has long been known that beef has a greater environmental impact than other meats, the authors of this paper say theirs is is the first to quantify the scale in a comparative way. 
  
 Beef footprint 
  
 The researchers developed a uniform methodology that they were able to apply to all five livestock categories and to four measures of environmental performance. 
  
 "We have a sharp view of the comparative impact that beef, pork, poultry, dairy and eggs have in terms of land and water use, reactive nitrogen discharge, and greenhouse gas emissions," lead author Prof Gidon Eshel, from Bard College in New York, told BBC News. 
  
 "The uniformity and expansive scope is novel, unique, and important," he said. 
  
 The scientists used data from from 2000-2010 from the US department of agriculture to calculate the amount of resources required for all the feed consumed by edible livestock. 
  
 They then worked out the amount of hay, silage and concentrates such as soybeans required by the different species to put on a kilo of weight. 
  
 They also include greenhouse gas emissions not just from the production of feed for animals but from their digestion and manure. 
  
 As ruminants, cattle can survive on a wide variety of plants but they have a very low energy conversion efficiency from what they eat. 
  
 As a result, beef comes out clearly as the food animal with the biggest environmental impact. 
  
 Image copyright SPL Image caption The scientists have developed a methodology to compare the relative impacts of different protein sources 
  
 As well as the effects on land and water, cattle release five times more greenhouse gas and consume six times more nitrogen than eggs or poultry. 
  
 Cutting down on beef can have a big environmental impact they say. But the same is not true for all livestock. 
  
 "One can reasonably be an environmentally mindful eater, designing one's diet with its environmental impact in mind, while not resorting to exclusive reliance on plant food sources," said Prof Eshel. 
  
 "In fact, eliminating beef, and replacing it with relatively efficiency animal-based alternatives such as eggs, can achieve an environmental improvement comparable to switching to plant food source." 
  
 Other researchers say the conclusions of the new study are applicable in Europe, even though the work is based on US data. 
  
 "The overall environmental footprint of beef is particularly large because it combines a low production efficiency with very high volume," said Prof Mark Sutton, from the UK's Centre for Ecology and Hydrology. 
  
 "The result is that the researchers estimate that over 60% of the environmental burden of livestock in the US results from beef. Although the exact numbers will be different for Europe (expecting a larger role of dairy), the overall message will be similar: Cattle dominate the livestock footprint of both Europe and US." 
  
 Follow Matt on Twitter @mattmcgrathbbc. ||||| Raising cows for beef requires substantially more land, water, greenhouse gas emissions and fertilizer compared to other livestock in the American diet. 
  
 Beef production takes a big toll on the environment, according to one of the most comprehensive studies to date on livestock management in the United States. 
  
 To make one steak, 28 times more land, 11 times more irrigation water, five times more greenhouse-gas emissions and six times more fertilizer is needed compared to what's required for other sources of commonly eaten protein, like pork and poultry, the researchers found. 
  
 "We were trying to see how many resources we take from planet Earth in order to create what we are eating," Ron Milo, the study's co-principal investigator and a professor of plant sciences at the Weizmann Institute of Science in Israel, told Live Science. "We found that it is much larger for eating beef." [7 Perfect Survival Foods] 
  
 Milo and his colleagues collected data on the environmental costs per calorie of dairy, poultry, pork, eggs and beef — foods that account for 96 percent of the calories Americans get from animals. The researchers consulted records from the U.S. Department of Agriculture, the Department of the Interior and the Department of Energy from 2000 to 2010. 
  
 The environmental costs of dairy, poultry, pork and eggs are fairly similar, the researchers found. 
  
 Plants — including potatoes, wheat and rice — require even fewer resources, the researchers also reported. Compared to plants, nonbeef animals require an average of six times as much land, half as much irrigation water, two times as much greenhouse-gas emissions and three times as much fertilizer use. 
  
 In contrast, the same number of calories from beef is much more taxing on the environment — requiring 160 times more land, eight times more irrigation water, 11 times more greenhouse-gas emissions and 19 times more fertilizer than plants, according to the researchers. 
  
 The costs include the land, water and fertilizer needed to grow food for the animals. For instance, the researchers based greenhouse-gas emissions on methane associated with the animals' flatulence and manure, and pollutants associated with the tractors and fertilizer production. 
  
 Other studies have identified beef as a major drain on environmental resources, but this is one of the largest investigations on the environmental costs of livestock in the United States, said Nathan Pelletier, president of the Global Ecologic Environmental Consulting and Management Services in British Columbia, Canada. 
  
 "It's a good message to reiterate," Pelletier told Live Science. "What remains to be seen is to what extent this information will influence policymaking." 
  
 Still, the new study can help people make informed decisions about what to eat for dinner, the researchers said. 
  
 "Maybe I like beef very much," Milo said. "But from knowing those numbers, maybe I could just eat it once a week, or once every two weeks." 
  
 The researchers published the findings today (July 21) in the Proceedings of the National Academy of Sciences. 
  
 Follow Laura Geggel on Twitter @LauraGeggel and Google+. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science. |||||

Think drive-thru cheeseburgers are cheap? Think again. What may be light on the wallet is heavy on the planet, according to a new study on the environmental costs per calorie of beef, pork, poultry, dairy, and eggs—which, combined, make up 96% of the calories Americans get via animal sources. But, as LiveScience reports, the worst offender is beef: Not only does it require about 10 times the resources as pork and poultry (including 28 times the land), but when compared to calories gotten from plants, beef uses 160 times more land, 19 times more fertilizer, 11 times more greenhouse-gas emissions, and 8 times more irrigation water. While this isn't the first study to pinpoint the resources used to raise cattle, the authors say it is one of the largest ever conducted to investigate the full extent of environmental costs across different types of livestock in the US, thereby allowing for direct comparisons. Not ready to drop meat from your diet altogether? "Eliminating beef, and replacing it with relatively efficient animal-based alternatives such as eggs, can achieve an environmental improvement comparable to switching to plant food source," one researcher tells the BBC. Other researchers say the conclusions can likely be extended to Europe. (Check out what is predicted to happen if the whole world suddenly goes vegetarian.)