They have a large amount of cattle. Just read an article in the FT (would link but on mobile) about Ireland looking to cull 200k cows to help balance their methane emissions.
Ireland has 7.5m head of cattle[1] - I think that qualifies as a "large amount". And you can add 6m head of sheep and over 1.5m pigs. About 40% of Ireland's CO2 equivalent comes from agriculture/agri-business.
Montana doesn’t even make the top ten list for cattle per state. It’s more that there is nobody there except cattle, not that it is a cattle dense location. That’s only about 3% of the cows in the US.
Montana has more cows than humans.
Montana has more than twice as many cows as humans.
1.1 million residents and 2.6 million head of cattle.