Border Collies and Aussies want to "chase" when they are younger so do the Great Pyrenees. It's just puppy behavior, and if your lucky your pup won't.
What I have done is just always take them with you to feed and water. Never let them play with the chickens, no rough house at all. This way...
Good choice, as I sit here and type I hear my Great Pyrenees barking at.... um.... I think the snow?? I'm not sure though. I love her to death but my gosh does she bark at everything. I have her up at the house at the moment so she can be with the family for the winter. She doesn't have anything...