Obviously it is not one of life's most important questions - but how much greenhouse gas is released when cows belch?
A Swedish university has received 3.8 million kronor £300,000 in research funds to find the answer.
About 20 cows will participate in the project run by the Swedish University for Agricultural
Cattle release methane, a greenhouse gas believed to contribute to global warming, when they digest their food.
Researchers believe the level of methane released depends on the type of food the eat.
Project leader Jan Bertilsson said that the cows involved in the study will have different diets and wear a collar device measuring the methane level in the air around them.
