As to cow flatulence, Oz herbivores have grown up on lean pickings, and have developed digestive processes and bugs that better utilise feed (and don't make methane).
Oz scientists are trying to get that to cross to cows, primarily to reduce the methane emissions.
I know that there are those on this board who will call it cooky, but imagine doubling the "fuel efficiency" of a cow, and tell me why that's bad.