The reason why cows belch.

Cattle eat into the rumen feed, in the process of strong fermentation of microorganisms, continue to produce a large amount of gas. About 6 to 1300 liters of gas can be produced in a day and night, mainly carbon dioxide and methane and a small amount of hydrogen, oxygen, nitrogen, hydrogen sulfide, etc., about 1/4 of which are absorbed into the blood and excreted through the lungs, some of which are used by microorganisms in the rumen. The rest is excreted by belching. Cattle generally belch an average of 17 to 20 times per hour. Rumen swelling often occurs because of a large number of delicate grass, and acute inflation is formed because a large amount of gas is produced by rapid fermentation of feed in the rumen, which can not be eliminated in time.