Burping

Some cultures[9] regard burping as acceptable in certain situations. In South Asia, for example, it signals the host that the guest has enjoyed the food and is full.

In Japan, burping during a meal is considered bad manners.[10] Burping during a meal is also considered unacceptable in Western cultures, such as North America and Europe.[9] In Middle Eastern countries, it is not acceptable to burp out loud in public, and one should silence one's burp, or at least attempt to do so.

An illustration depicting a woman burping an infant over her shoulder.

Babies are likely to accumulate gas in the stomach while feeding and experience considerable discomfort (and agitation) until assisted. Burping an infant involves placing the child in a position conducive to gas expulsion (for example against the adult's shoulder, with the infant's stomach resting on the adult's chest) and then lightly patting the lower back. Because burping can cause vomiting, a "burp cloth" or "burp pad" is sometimes employed on the shoulder to protect clothing.[11]

The current Guinness World Record for the loudest burp is 109.9 dB, set by UK's Paul Hunn at Butlins in Bognor Regis on 23 August 2009.[12] This is louder than a jackhammer at a distance of 1 m (3 ft 3 in).[13]

It is possible to voluntarily induce burping through swallowing air and then expelling it, and by manipulation of the vocal tract produce burped speech.

While this is often employed as a means of entertainment or competition, it can also act as an alternative means of vocalisation for people who have undergone a laryngectomy, with the burp replacing laryngeal phonation. This is known as esophageal speech.

Much of the gas expelled is produced as a byproduct of the ruminant's digestive process. These gasses 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,[14] i.e. more than 117 kg per year through burping and exhalation, making commercially farmed cows a major (37%)[15] contributor to anthropogenic methane emissions, and hence to the greenhouse effect. 95% of this gas (wind) is emitted through burping.[16] 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.[17]

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.[18]

The failure to burp successfully can be fatal. This is particularly common among domesticated ruminants that are allowed to gorge themselves on spring clover or alfalfa. The condition, known as ruminal tympany, is a high-pressure buildup of gas in the stomach(s) and requires immediate treatment to expel the gas, usually the insertion of a flexible rubber hose down the esophagus, or in extreme cases the lancing of the animal's side with a trochar and cannula.

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 rarely builds up in the gastrointestinal tracts of birds.[19]