It’s absolutely doable, but not as easy as it seems if you want to have correct results.
There are very precise tags for pastures in OSM but are rarely used. You can place animals in every meadow but you will end with cows in the middle of a city or even worse, in an airport area as some are marked as… meadows.
A lot of data analysis, huge data amounts to parse, and lots of manual labor. Had the plan to develop something like this with some other features added, but I guess I’m late to the party.