Unless of course the cat prefers to stalk & eat wild birds and poultry.

Then they're just another livestock predator and decimater of the local wild bird ecosystem - and a human-introduced, nonnative, invasive species at that.

Plus, semi-feral cats roaming the wild introduce disease to human children with their fleas, parasites, rabies, cat scratch fever, and the cat-feces specific illness that endangers pregnant women who work the garden soil.

Eeewww.

Oh but they look so cute.

Maybe. I was considering my suburban/high density amateur garden.

I think the traditional farm cat is specifically for crop stores in the countryside. It might deter foxes from chickens too.

Our street probably has a cat density of 1 per house. None of them are hard enough to take on a rat/stoat/weasel/mink etc. Their only adrenalin rush is crapping in our veg when no-one is watching..

My mum lives in a more rural setting. Losing chickens to mysterious deaths is expected. I think you would need to give a cat a hard life if you want it to work for you - they are willful sods.