My two dogs are smart and learn quickly. For mine I simply brought out some of my tamest birds and allowed the dogs watch me handle the birds while looking at the dogs repeatedly and saying, "NO-MINE". The dogs learned long ago to not touch anything that's, "MINE".
I hired a dog trainer who really helped with my shepherd mix. She likes to herd the chickens to death. He had me use a shock collar and it's worked really well. I recommend finding a competent dog trainer in your area and have your dog evaluated first. My dog was behaving out of instinct so she was easily broken out of it. Your dog might be something else that can't be trained out of it. Good luck.
She won't touch a chicken unless the chicken is scared and runs. Then she runs like a bullet after them. She killed one roo already. I like the shock collar idea. Thanks.