You never, ever trust your cats around the chicks, that's what you do. I don't care how docile your cats are or how long they've been indoor cats- they're still predators and they WILL at some point take a swipe at a chick. Now when the chicks are grown it might be a different story. If they're standards, then the chickens can probably take care of themselves. Not sure about bantams as I don't have any. My chicks are 5 weeks old and in a coop and covered run full time, but my two youngest cats still hang around and watch, just like they did when they were little babies in the brooder. I don't trust them one little bit at this point. I have indoor cats too and never trusted them either.