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.
[1] https://ahdb.org.uk/news/irish-cattle-and-sheep-numbers-rise...