I agree 100% with dainerra. I'm working on training my 3rd dog that I've had around chickens. This one is more of a challenge as she really wants to kill them. I just finished my first obedience class with her and we worked a lot on the "leave it" command. This is critical. Now that I have that perfected the command using food (I put food down, say leave it, and when she leaves it alone and looks at me she gets a treat - NOT the treat I put down on the ground, though - she never gets that one), I let one chicken out in the yard with the dog on a leash, walk the dog by the chicken and if she looks at the chicken I say leave it. When she looks away from the chicken and looks at me she gets a treat. I expect to keep working on this type of training for as long as it takes until it becomes automatic.
Although I was proud of myself because I had trained my last 2 dogs being trustworthy around the chickens unattended, I am not sure I will ever trust this one unless I'm around, but we'll keep working on it anyway.