Save the cows

According to Dr. James L. A. Roth, the author of Gastrointestinal Gas (Ch. 17 in Gastroenterology, v. 4, 1976) most people (2/3 of adults) pass farts that contain no methane. If both parents are methane producers, their children have a 95% chance of being producers as well. The reason for this is apparently unknown. Some researchers suspect a genetic influence, whereas others think the ability is due to environmental factors. However, all methane in any farts comes from bacterial action and not from human cells.

The domestic animal population has increased by 0.5 to 2.0 percent per year during the last century, according to the Environmental Protection Agency (EPA) report Policy Options for Stabilizing Global Climate (Lashof and Tirpak 1990). Figure 4-14 of the report shows the upward trend in domestic animal populations. One result of this population increase is that emissions from livestock have become a significant source of atmospheric methane. In fact, domestic animals currently account for about 15 percent of the annual anthropogenic methane emissions.

Much of the world's livestock are ruminants--such as sheep, goats, camel, cattle, and buffalo--who have a unique, four-chambered stomach. In the chamber called the rumen, bacteria break down food and generate methane as a by-product. The production rate is affected by factors such as quantity and quality of feed, body weight, age, and exercise, and varies among animal species as well as among individuals of the same species. Chapter 4 of the EPA report provides an overview of livestock methane emissions.

In "Methane Emissions from Animals," Lerner, Matthews, and Fung (1988) estimate that of the annual global production of 400 to 600 Tg (1Tg=1 million tons) of methane, enteric fermentation in domestic animals contributes approximately 65 to 85 Tg. The authors present a global high-resolution database of methane emissions from animals (including cattle, water buffalo, sheep, goats, camels, pigs, horses, and caribou). Plates 1a-1h illustrate global distribution of animal populations and methane emission. Table 1 shows population statistics and associated methane emissions for seven animal types for 1984; table 2 presents total annual methane emissions by domestic animals for several countries in 1984; and table 3 shows latitudinal distribution of 1984 methane emissions by animal type and of total annual emissions by domestic animals.

Leng (1993) provides data on world ruminant population densities, estimated methane production rates, and factors influencing methane production in "Quantitative Ruminant Nutrition - A Green Science." The author estimates that ruminants on low quality feeds produce more than 75 percent of the total livestock methane emissions.

Donald E. Johnson1 and Gerald M. Ward1(1) Department of Animal Sciences, Colorado State University, 80523 Fort Collins, CO, USA


Abstract The enteric methane emissions into the atmospheric annually from domestic animals total about 77 Tg. Another 10 to 14 Tg are likely released from animal manure disposal systems. About 95% of global animal enteric methane is from ruminants, a consequence of their large populations, body size and appetites combined with the extensive degree of anaerobic microbial fermentation occurring in their gut. Accurate methane estimates are particularly sensitive to cattle and buffalo census numbers and estimated diet consumption. Since consumption is largely unknown and must be predicted, accuracy is limited often by the information required, i.e., distribution of animals by class, weight and productivity. Fraction of the diet lost as enteric methane mostly falls into the range of 5.5"6.5% of gross energy intake for the world's cattle, sheep and goats. Manure methane emissions are heavily influenced by fraction of disposal by anaerobic lagoon. Non-ruminants, i.e., swine, become major contributors to these emissions.
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Thorpe, Andy (2008)

... domestic animals currently account for about 15 percent of the annual anthropogenic methane emissions.

Thanks, Deb! I know know heaps more about this subject than I did half an hour ago!

After all, they replaced much larger herds of bison, elk, antelope, etc., etc.

Global Warming occured at the end of the Dinosaur era and the forests died back at the same time the grasses and flowers evolved... the dinosaurs may have farted themselves to death by increasing the greenhouse gases... the higher levels of potassium in flowers may have caused dinosaur eggs to become brittle and this caused their extinction. Whichever