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In beef production, cow-calf phase contributes most greenhouse gases

Date:
January 30, 2013
Source:
American Society of Animal Science
Summary:
A new study shows that nursing cows are a major source of methane in beef production. By better understanding cattle nutrition and methane emissions, the beef industry could reduce environmental impact.
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FULL STORY

Scientists have long known that cattle produce carbon dioxide and methane throughout their lives, but a new study pinpoints the cow-calf stage as a major contributor of greenhouse gases during beef production.

In a new paper for the Journal of Animal Science, scientists estimate greenhouse gas emissions from beef cattle during different stages of life. They show that, depending on which production system farmers used, beef production has a carbon footprint ranging from 10.7 to 22.6 kg of carbon dioxide equivalent per kg of hot carcass weight.

According to study co-author Frank Mitloehner, an associate professor in the Department of Animal Science at UC Davis, one source of greenhouse gases was surprising.

"If you look at everything that contributes to greenhouse gases through the beef supply chain, then it is the cow-calf that produces the greatest greenhouse gases," Mitloehner said.

In the cow-calf phase, the cow gives birth and nurses the calf until the calf is six to 10 months old. During this time, the cow eats rough plants like hay and grasses. The methane-producing bacteria in the cow's gut thrive on these plants.

"The more roughage is in the diet of the ruminant animal, the more methane is produced by the microbes in the gut of the ruminant, and methane comes out the front end," Mitloehner said.

In feedlots, by contrast, cattle eat mostly corn and grains, which the methane-producing bacteria cannot use as effectively.

Methane is one of the most important greenhouse gases. Methane has a greater capacity to trap heat in the atmosphere than carbon dioxide.

The beef industry has been paying close attention to greenhouse gas emissions in recent years.

"We are doing a lot to measure and mitigate our impact," said Chase Adams, director of communications for the National Cattlemen's Beef Association.

In a 2011 paper for the Journal of Animal Science, researcher Jude Capper showed that the beef industry today uses significantly less water and land than 30 years ago. The industry has also reduced its carbon footprint by 16.3 percent per billion kilograms of beef produced.

According to Mitloehner, beef producers can further reduce their carbon impact by using new technologies like growth promotants. However, consumers are often uncomfortable with these methods, and they choose organic beef or beef with reduced amounts of growth promotants.

"The technologies many consumers are critical of are those that help us receive the greatest environmental gains," Mitloehner said.


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The above post is reprinted from materials provided by American Society of Animal Science. Note: Materials may be edited for content and length.


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American Society of Animal Science. "In beef production, cow-calf phase contributes most greenhouse gases." ScienceDaily. ScienceDaily, 30 January 2013. <www.sciencedaily.com/releases/2013/01/130130132451.htm>.
American Society of Animal Science. (2013, January 30). In beef production, cow-calf phase contributes most greenhouse gases. ScienceDaily. Retrieved July 6, 2015 from www.sciencedaily.com/releases/2013/01/130130132451.htm
American Society of Animal Science. "In beef production, cow-calf phase contributes most greenhouse gases." ScienceDaily. www.sciencedaily.com/releases/2013/01/130130132451.htm (accessed July 6, 2015).

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