Either release the methane into the air or burn it for energy. Otherwise…
(from the BBC):
German cows cause methane blast in Rasdorf, Germany
Methane gas released by dairy cows has caused an explosion in a cow shed in Germany, police said. The roof was damaged and one of the cows was injured in the blast in the central German town of Rasdorf.
Thanks to the belches and flatulence of the 90 dairy cows in the shed, high levels of the gas had built up. Then “a static electric charge caused the gas to explode with flashes of flames” the force said in a statement quoted by Reuters news agency.
Emergency services attended the farm and took gas readings to test for the risk of further blasts, said local media.
Cows are believed to emit up to 500 litres of methane each per day.
Cattle ranching is a polluting business – methane is a potent greenhouse gas and cows also release large amounts of ammonia, which can lead to toxic acidification of soil and water bodies.