Monday, June 8, 2009

Cows, Methane Gas and Climate Change

The consensus of scientists believe that human activities are changing the composition of the atmosphere, and that increasing the concentration of greenhouse gases will change the planet's climate. However, they are not sure by how much it will change, at what rate it will change, or what the exact effects will be. Currently carbon dioxide is thought to be the critical greenhouse gas. According to NOAA, National Oceanic and Atmospheric Administrations, CH4 which absorbs 25 times the heat of CO2 is present in the atmosphere at 1/50 the level of CO2 at 1.8 ppm. Methane levels in the atmosphere have risen for the first time since 1998. This increase was attributed to changes in the permafrost stores of methane. (According to NOAA, CO2 is present at 386 ppm.)

Lately, there seems to be a focus by environmental groups and nutrition activists on increasing meat consumption as the cause of the increase in methane and greenhouse gasses. The Center for Science in the Public Interest, Nutrition Action Newsletter points out that the consumption of animal products increases global warming due to a variety of causes and argues for the vegetarian life. CH4 is produced as part of normal digestive processes in animals. During digestion, microbes present in an animal’s digestive system ferment food consumed by the animal. This microbial fermentation process, referred to as enteric fermentation, produces CH4 as a byproduct, which can be exhaled or eructated by the animal. The amount of CH4 produced and emitted by an individual animal depends primarily upon the animal's digestive system, and the amount and type of feed it consumes. Ruminant animals including cows are the major emitters of CH4 because of their unique digestive system. Ruminants possess a rumen, or large "fore-stomach," in which microbial fermentation breaks down the feed they consume into products that can be absorbed and metabolized. The microbial fermentation that occurs in the rumen enables them to digest coarse plant material that non-ruminant animals can not. Ruminant animals, consequently, have the highest CH4 emissions among all animal types. In addition to the type of digestive system, an animal’s feed quality and feed intake also affects CH4 emissions.

On Friday in the New York Times was an article by Leslie Kaufman, “Greening the Herds: A New Diet to Cap Gas.” For the past five months cows at 15 farms across Vermont have had their grain feed adjusted to include more plants like alfalfa and flaxseed and less corn. This feed is more like the natural grasses that the cows evolved eating. The methane output of the Vermont cows dropped 18 percent while milk production remained stable. In addition to producing less methane, the cows were observed to be healthier. This study evolved out of research performed by the makers of Danon yogurt in France. Scientists working with Groupe Danone had been studying why their cows were healthier and produced more milk in the spring. The answer, the scientists determined, was that spring grasses are high in Omega-3 fatty acids, which may help the cow’s digestive tract operate smoothly.

Corn and soy, the feed that became dominant feed in the agro-industrial dairy industry, has a completely different type of fatty acid structure. The French sturdy found a reduction in methane release of about 30% at 600 farms. The difference from the Vermont experience was attributed to the fact that the Vermont animals were pastured and received some of their food from grasses. As was carefully chronicled in Michael Pollan’s book “The Omnivore’s Dilemma” during the past 40 years, our agricultural economy as orchestrated by the Department of Agriculture has created a system of fattening cows using an unnatural feed, corn and soy. Cows are healthier and belch less methane if they are feed a diet similar to one they evolved to eat. This should not be surprising and is a small example of unintended consequences of man trying to bend the earth to our will. Our tools to impact and change remain far more powerful than our wisdom to know the right course of action to take with them. We would be far better off if we could restrain ourselves from wide sweeping actions and dip our toes in first to see the results. Try to develop wisdom before we try to manage the natural cycles of the earth, and instead follow the earth’s lead.

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