A barn cat isn't a house pet. It's a worker whose job is killing mice.
Why
One mouse eats 3 kg grain/year. Colony of 50 mice = 150 kg grain. One cat catches 5-10 mice/week. 2-3 cats = mouse-free barn. No chemicals, no traps, free.
Which Ones
Regular, mixed breed. Amish don't buy cats — get from neighbors. Best hunters: lean, fast, semi-feral. A fat lazy cat doesn't catch mice.
Care
Minimal. Morning milk (optional — a good hunter eats mice). Shelter in barn (hay). Neutering — no (Amish generally don't). Kittens given to neighbors.
Attitude
Functional. Cat lives in barn, not house. Petting is fine, but not the purpose. Purpose — no mouse droppings in grain. Dies — get another. No sentimentality, but no cruelty either.