I do not know about Hitler's gastric emissions, but I do know a little about cows having grown up with them; they do not fart “massively”. I spent a lot of time in barns with cows and they have a digestive system that is better equipped for eating a diet completely made up of plant life than people do. This cow farting thing is made up completely by nonsense made up by lefty idiots who have no idea what they are talking about.
You’re right:
Cattle are ruminants, meaning their digestive system is highly specialized to allow the use of poorly digestible plants as food. Cattle have one stomach with four compartments, the rumen, reticulum, omasum, and abomasum, with the rumen being the largest compartment. The reticulum, the smallest compartment, is known as the “honeycomb”..
https://en.wikipedia.org/wiki/Cattle