Many other
mammals, such as
cows,
dogs and
sheep, also burp.
Ruminants Much of the gas expelled is produced as a
byproduct of the ruminant's
digestive process. These gases notably include a large volume of
methane, produced exclusively by a narrow cohort of
methanogenic
archaea in the animal's gut;
Escherichia coli (
E. coli) and other bacteria lack the enzymes and cofactors required for methane production. A lactating cow produces about 322g of methane per day,
i.e. more than 117 kg per year through burping and exhalation, making commercially farmed cows a major (37%) contributor to anthropogenic
methane emissions, and hence to the
greenhouse effect. 95% of this gas (wind) is emitted through burping. This has led scientists at the
Commonwealth Scientific and Industrial Research Organisation of
Perth,
Australia, to develop an anti-methanogen vaccine to minimize methane in cow burps. One reason why cows burp so much is that they are often fed foods that their digestive systems cannot fully process, such as
corn and
soy. Some farmers have reduced burping in their cows by feeding them
alfalfa and
flaxseed, which are closer to the grasses that they had eaten in the wild before they were domesticated.
Birds There is no documented evidence that birds burp, though
ornithologists believe that there is nothing which physiologically prevents them from doing so. However, since the
microbiota of birds do not include the same set of gas-producing bacteria that mammals have to aid in digestion, gas hardly builds up in the
gastrointestinal tracts of birds. == See also ==