I got my blue nose pit bull puppy after getting my 2nd batch of chicks. She was introduced to them, and showed no interest in them. I even cuddled both the chicks and puppy at the same time. My puppy has never been aggressive towards any animal, completed 18 weeks of puppy training and is very disciplined.
Once my chicks were grown and free ranging on their fenced off side of the yard my puppy showed more interest in them and would accompany me each day when I would clean their coop, feed & water them.
One day she started chasing the chickens playfully and I called her back and scolded her because I didn't want her thinking they were toys because she shakes and rips her toys apart. So she never chased them again.
Then one day while my puppy was outside and and I went to call her inside she didn't come like she usually did. I was horrified to find her on the chicken's side of the fence and she had killed a chicken and eaten most of it. I had to pick up the scattered pieces of my chicken that she didn't eat and a ton of feathers everywhere. It was so awful and sickening.
I asked my trainer if there was any way she could be trained to protect my chickens instead of hunt them but she said because my puppy actually hunted and ate a chicken instead of playing with it and accidentally killing it, that unfortunately some dogs are hunters, regardless of their training or even their breed.
I've seen other pit bulls protect their chickens and be affectionate towards them but sadly mine wants to eat them. It's very odd because she is not aggressive with any other animals, from the doves and stray cats that wander in our yard to our pet parrots and cat, or young children or other dogs small or large at the dog park. If we're walking in the neighborhood and an aggressive dog barks or lunges she doesn't even bark back or engage. So she's not an aggressive pit bull unless you're a chicken apparently.