@neru
I worked for a veterinarian who treated cats exclusively so what I say comes from that particular experience.
Cats are obligate carnivores & must have meat, unlike dogs who can subsist on veggies & other things for a while, cats don’t do well for long with that. Unfortunately, it is expensive caring for cats; I am on my last cat & know how tough it is.
If you feed them strictly dry food, they will get what meat they need from the wildlife around you, esp. birds & mice. The wildlife around you will start to disappear, as it did in the Outback, because so many cats were dumped there, they destroyed the natural fauna. Bounty money was finally placed on cats due to this.
All you can do is whatever you can do. If it’s dry food, so be it. Feral cats live 3 to 5 years, sometimes less. Due to the vermin they eat, Toxoplasmosis is a risk so please don’t handle them. I’ve had Toxo & it’s ugly.
Check to see if there’s a service that will neuter the male cats to be released back into the wild if you trap them.
There’s not much more I can tell you, except that cat bites & scratches are very dangerous, more so than dogs because of the number & type of pathogens they carry. Cats also present Rabies symptoms twice as fast as dogs because of the higher body temp.
It’s a sad situation and I feel your pain. Unfortunately, as economies falter, there’s likely more to come. Do what you can & that’s it. So sad, I know…