Outdoor cats for a farm setting

[Alex]

No, I didn't have lazy cats. Ours were very accomplished hunters.

But assuming you're providing some base level of food to the cats it can still blunt their desire to hunt; while many cats hunt incessantly regardless of hunger, others operate on a more "as needed" basis. Not all cats are equally vigorous in pursuit of all prey, we once a hat a cat that would just sit and watch the other cat hunt mice but she was brutal in pursuit of squirrels and birds.

Plus, in a rural setting mice are simply omnipresent and there'll always be a ready source for new visitors. You probably wouldn't have an overwhelming infestation but new mice are going to come along and be seen from time to time.

Plus, if the cats are feral there is no guarantee they'll stick around to hunt the areas you want hunted.

One negative of using feral cats for mousing beyond their own shortened lifespan is that you don't get any say in what they kill. They'll also go after squirrels (our squireller was also very keen on finding nests and eating the young and for a while there were almost no squirrels left in our area), birds, small lizards, large bugs, etc.