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Hot air doesn’t just come from cattle

Not all science is good science, and sometimes good journals can publish bad science

Hot air doesn’t just come from cattle

In late July, a very popular and well-respected scientific journal called Proceedings of the National Academy of Sciences published “Land, irrigation, water, greenhouse gas, and reactive nitrogen burdens of meat, eggs, and dairy production in the United States” (PNAS 111:11996-12001).

The authors, a physicist from Bard College in New York, a physicist and a graduate student from Weizmann Institute of Science in Israel, and a Yale graduate student with a master’s degree in political science, looked at life cycle assessments (LCAs) for livestock. An LCA estimates environmental impacts by looking at the inputs used (e.g. energy, feed, fertilizer, water, etc.) and outputs generated (e.g. greenhouse gases, smog, manure, fertilizer run-off, etc.) when meat, milk or eggs are produced, processed, transported, distributed, consumed, and recycled.

The authors acknowledged that regional variations in production systems and environments are important: “the results of an LCA conducted in Iowa, for example, are unlikely to represent Vermont or Colorado.” Because daily feed intake, feed:gain, and intake on pasture vary with season, region, and technology use, “one research effort, focused on a single location, is unlikely to yield definitive results.”

What they did: They extrapolated the results of an LCA conducted in Iowa to the rest of the U.S. by incorporating USDA regional data on land and fertilizer use, feed production, irrigation practices and cattle numbers.

What they learned: Beef have a larger environmental footprint than chickens or swine. This isn’t news. Cattle are bigger, live longer, are raised on less productive land and consume more forage than chickens and pigs. So it’s no surprise that cattle need more feed, water and land, or that they produce more greenhouse gases than chickens or pigs.

What it means: This paper is flawed. Despite the fact that they criticized previous studies for using region-specific data to depict a broader geography, they did just that. After criticizing past LCAs for being based on weak data, they did not gather or incorporate any new data into their own study.

Pardon me, but your bias is showing: The authors referred to the FAO’s 2006 “Livestock’s Long Shadow” report, which stated that livestock are responsible for more greenhouse gas emissions than all of the world’s transportation combined. They failed to mention, “Clearing the Air” (Adv. Agron. 103:1-40), which clarified many of the oversights in “Livestock’s Long Shadow.” They also failed to mention the FAO’s more recent 2013 “Tackling Climate Change Through Livestock” report, which used a much more rigorous and sound methodology to assess livestock’s environmental impacts.

Unfortunately, not all science is good science, and sometimes good journals publish bad science. Remember, it took 12 years for a leading medical journal (The Lancet) to retract a 1998 paper that suggested childhood measles/mumps/rubella vaccines were linked to autism. In the meantime, some well-meaning but misguided celebrities influenced a lot of concerned parents to not vaccinate their children.

Why you should care: This paper doesn’t encourage barley- versus corn-fed, or grain- versus forage- or grass-finished, or conventional versus hormone- and antibiotic-free production, or natural versus organic, or animal welfare approved, or local versus commodity production systems. This paper supports not eating beef, regardless of how it is raised, and was published by a highly respected journal that is read by influential scientists around the world.

What we are doing: Canada’s beef producers are constantly trying to reduce land, feed, energy and water use, improve range health and reduce nutrient and greenhouse gas losses. Improved production efficiencies often have environmental benefits.

Tim McAllister (AAFC Lethbridge) is leading a Beef Cluster project to measure how Canada’s beef industry’s feed, land, and water use, greenhouse gas production, carbon sequestration and biodiversity have changed since 1980, and identify ways to improve further.

The Canadian Roundtable for Sustainable Beef is developing a sustainability assessment. Like the Beef Quality Audit, this will be a scorecard to identify where our industry is improving, and where we can still do better. The historical context from the cluster project, plus the ongoing sustainability assessment will help the industry to better respond to consumer questions, concerns, interests and demands for sustainable beef.

The single most meaningful environmentally beneficial dietary change they can make is to reduce food waste. A 2011 FAO study found that the average North American consumer wastes more than 115 kg of food each year. In North America, nearly 25 per cent of the cereal products (e.g. bread, pastas), 25 per cent of fish products, 18 per cent of the fruit and vegetable products, 15 per cent of the root and tuber products (e.g. carrots, potatoes), 15 per cent of dairy products, eight per cent of meat products, and five per cent of oilseed products (e.g. vegetable oil, margarine) are lost due to consumer-level waste.

That’s worth telling your friends and relatives.

The Beef Research Cluster is funded by the National Checkoff and Agriculture and Agri-Food Canada with additional contributions from provincial beef industry groups and governments to advance research and technology transfer supporting the Canadian beef industry’s vision to be recognized as a preferred supplier of healthy, high-quality beef, cattle and genetics.

Dr. Reynold Bergen is the science director of the Beef Cattle Research Council.

About the author


Dr. Reynold Bergen is the science director of the Beef Cattle Research Council.

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