Also, always give them your an your neighbors food scraps, chickens can no more eat just pellets than humans can, it drives you insane and unhealthy. Add fresh roadkill to their diet if you can mince it especially. The best thing that ever happens to a chicken is to get some slightly off mince...
I think it may be correct about internal parasites. I don't give mine chemicals or anything that I have no idea what is in it. After all, some bottle full of chemicals is not what I want in my food. I do eat the chickens as well as the eggs when there are too many roosters.
As far as I know...