How old is your dog? If she is not very young, it can take a long longer to "break" a habit she already has. On the other hand, if she IS young, it will be a long time before you can reliably trust her.
After searching what seemed forever for a pup, we finally had someone bring over a collie mix pup and try him with our chickens and ducks. He was actually a bit afraid of them, and wasn't interested in chasing them at all. So we decided to give it a go. He was about 9 weeks old at the time.
He's turned out to be a very smart dog (and I used to train GSD's as well as a few other dogs, so I can say that he really is smart). I believe he's got quite a bit of golden retriever or perhaps yellow lab into the mix as well. Although he's smart, I never intended to get a hunting-type dog around my birds, and a collie would not have been my first choice either. It was a case of beggars not being able to be choosers though, LOL.
He does want to "herd" the ducks, especially when he sees me herding them into the coop. And when he is bored, he really would like to chase the chickens (and has done so once or twice).
I've worked with him a LOT over the past couple of months we've had him, often keeping him tied to me when I'm outside. I've corrected him MANY times for even looking sideways at the poultry, and I did spank him when he chased the chickens once. I've never allowed him outside completely unsupervised with them ... the closest I've come is him tethered with the birds free-ranging with me watching from the window. Even that is after a lot of working with him.
My red sex-links and RIRs want to "discipline" him as well, staring at him and pecking his nose if he watches them too closely, or if I get onto him. He will lie on the ground and let them come up and eat his food. (The drakes are a worse problem ... it's breeding season so they are becoming aggressive to him, and he thinks it looks like a fun game, so I have to be extra-vigilant.)
Even with all that working with him, his good behavior (for the most part) and temperament ... it will be a LONG time (if ever) before I am willing to leave him loose with the birds completely unsupervised. I had hoped he would guard them but ...
Perhaps his mere presence deters hawks. I hope. It should deter raccoons and such, since he wanders the yard both before the birds are let out and after they are put up. And he lets me know if dogs or cats get too near.
Still ... I don't know if he will ever be what I originally hoped. And I've had some experience working with dogs, and put a lot of time into this one. And he really is smart (generally he "gets" anything by simply being shown 3 times so I can train him incredibly fast ... him WANTING to do the thing is another matter, LOL.)
Basically though, he's a puppy, so I can't say right now how reliable and steady I will consider him to be when he grows up. I hope he DOES turn out to be a steady dog I can trust, but I just can't say. Especially with a mixed breed. Collies can be a bit flighty, and I know Aussies can be a difficult breed for poultry as well. They just have such a strong drive to herd and are so high-energy too.
If it were my dog, I'd work on training her as often as possible. Not only how to behave around the chickens, but lots of work in obedience. And give her a "job" to do, one that burns a lot of energy. Frisbee-chasing seems to be great for Aussies, but it might be better to channel the energy into something that doesn't involve "chasing" at all. Maybe you can teach her to "find" things by scent, and let her work at that. Or long-distance recall and obedience work. My daughter wants to train our dog for "dancing" ... the way some people choreograph dog's moves to music and their own moves. Most importantly, just give her a way to burn off that energy so she doesn't build up frustration and then give in to temptation to discharge it by chasing the birds.
Sorry for the long-winded post ... if you got through it, I hope something in there helps!
trish