The Logic of Porcology

Flatulence begets a great many people. But I am a bit confuszled, is it meat or vegetables that cause the most flatulent emissions? I ask because cows fart all the time, but my father says that meat causes plenty of gas in humans. No one attributes farts to Mountain lions, and they are strict carnivores. This is definitely food for thought, and please tell me if you have an opinion on the subject.