No way there was 18000 cows.
A cow is ~3ft by 7ft.
That is 54000ft by 126000ft.
Or, 10.2 miles by 23.8 miles.
Just for the bare minimum space the cows themselves take up.
Letting alone processing plants and parking lots.

The locals are saying 2500.
But, even if we move the decimal one place, it's still 1 by 2.3 miles.

If I was to guess I would suggest an 'experimental' shot lot that culled the cows and they set them on fire trying to get the insurance to pay out, and that somebody added a zero to increase the impact of the story.