Sorry about the loss. They are part of the terrier breeds. So genetically they hunt. Plus, pit bull itself isn't a breed rather a catch all term for dogs that look similar, that are the bully breeds: Staffordshire, bulldogs, etc. The dog just needs trading. Be prorated for the chain & chicken...
I don't know if you did this based on your post. The buzz-shock collars require that you "load"them like you would a clicker. You first teach the dog what you want done when gets the buzz-tone. Once that's reliable during practice without the high distraction them you move up to higher...
I've 3 dogs. An 8 year old Chihuahua, a 7 (in 6 days) Great Dane, & a 5 year old Chiweenie.
- How do you/did you train your dog(s) not to kill or mess with your chickens?
It was an issue of socialization, desensitizing, deterrent, & distraction training. Luckily I've taught them that...