I farmed myself most my life as did my father before me,my grandfather and so on for many generations.It's what we know.When storing grain on the farm as was done always for livestock and to sell it is essential to have a good number of cats around to keep the vermin at bay from our grain bins of oats and corn.When we shelled to sell or ground ear corn for livestock there would be a couple dozen cats around to catch the mice.Along with a couple good yard dogs too.We had quite the numbers of cats also.
We always supplemented our cats also with regular cat food most times.They had a job and they did it well.They were not pets but employees to the farm.
If you've ever seen a farms' buildings overrun by rats a person will see the value they are,and you'll never have enough .22 bullets to kill all the rats.The damage they can do to grain and buildings is very costly.A lot more than having cats around to suppress them.Even poisoning them does'nt slow them down if they get bad enough and the cost of poison is a lot more than keeping the cats around.
As kids on the farm we do things sometimes without seeing the big picture.I know I've been guilty of it.My father trusted me with a .22 too at a very young age,but started me with a BB and then a pellet gun first.
The feral cats the way I see it do do a fair amount of damage to our quail and pheasants along with the owls,hawks,coyotes,bobcats,and fox but they get after the field mice themselves too,and somehow I keep seeing new coveys of quail and hatches of pheasants yet too.
When mother cats here have kittens I see them almost every early morn coming out of the woods and fields carrying a mouse in their mouth and also see chipmunks that have been caught in the cat shed too.
What will kill the farm cat and smaller pet dogs around here is the old coyote.Especially around places occupied by elderly couples or possibly disabled that don't get outside or show activity on the yard much.The coyotes will get emboldened enough to come onto the yard to kill cats in broad daylight.Especially into the deepest or coldest part of the winter when food gets pretty scarce.