Have you ever wondered what happens to the hundreds of gallons of methane gas produced each day by cows and other grazing animals? You'd think there would be herds of farm-youth with lighters standing-by to activate enormous pyrotechnics at the cows' expense, right?
Thanks to yet another hilariously educational book by Mary Roach, I've learned the cows don't belch (or fart for that matter). They actually reroute their internal tubing to move the very flammable gas from their rumens to their lungs where it is mixed in with air to be diluted to nonflammable levels, and then they "quietly" breathe it out. That is especially important since the sound that amount of gas released in any other "pressurized" way would've been an open invitation to their predators giving away their exact location.