Esforços para reduzir a produção de metano em ruminantes

Agriculture accounts for an estimated 14% of greenhouse gases in the world. A significant portion of these emissions come from methane, which in terms of its contribution to global warming, is 23 times more powerful than carbon dioxide. The Food and Agriculture Organization reports that U.S. production of methane in agriculture could increase by 60% by 2030 [Source: Times Online (website in English)]. About 1.5 billion cows and billions of other animals existing pastures in the world emit dozens of polluting gases, including a large amount of methane. Two-thirds of all ammonia comes from cows.Cows emit a lot of methane through belching, and a lesser amount through flatulence, ie your pum. Statistics vary on how much methane the average dairy cow expels. Some experts say 100 to 200 liters per day, while others say it may reach 500 liters per day. Anyway, it's a lot of methane, comparable to the pollution produced by a car in a single day amount.

To understand why cows produce methane, it is important to know a little more about how they work. Cows, goats, sheep, and many other animals belong to a class called ruminant animals. Ruminants have four stomachs and digest their food in their stomachs instead of their intestines, as humans do. Ruminants eat food, regurgitate it as cud and eating it. The stomachs are full of bacteria (in English) that facilitate digestion, but also produce methane.

With millions of ruminants in Britain, including 10 million cows, a major initiative is underway to curb methane emissions there. Cows contribute 3% of all greenhouse gas emissions in England and 25 to 30% of its methane. In New Zealand, where the breeding of cattle and sheep is vitally important, 34% of greenhouse gases come from animals raised on the farm. A three-year study, which began in April 2007 by Welsh scientists are examining if adding garlic (in English) to cow feed can reduce their methane production. The study is ongoing, but early results indicate that garlic cut cow flatulence half by attacking the microbes that produce methane and live in the stomachs of cows [Source: BBC News (English site)]. Researchers are also trying to ascertain whether the addition of garlic affects the quality of the meat or milk produced and even if the animals get bad breath.

Another study from the University of Wales, Aberystwyth, is tracking quantities of nitrogen and methane produced by sheep, which provide a good model for comparison with the cows because they have similar digestive systems. The sheep of this study are living in plastic tunnels where their methane production is monitored through a variety of diets.

Many other efforts are underway to reduce the production of methane from ruminants, such as trying to breed cows that live longer and have better digestive systems. At the University of Hohenheim in Germany, scientists created a pill to trap gas in the rumen of the cow - the first stomach of ruminants - and convert methane into glucose. However, the pill requires a strict diet and structured feeding times, things that may not lend itself well to grazing.

In 2003 the New Zealand government has proposed a flatulence tax, which was not adopted because of widespread protest.

Other efforts look at grazing lands being used by livestock farmers, which will be discussed in the next section.

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