Not true. I have a Great Pyrenees that was given to me because she was a chicken killer. Now she is my chicken PROTECTOR!Once a chicken killer always a chicken killer.
http://www.backyardherds.com/forum/viewtopic.php?id=24453
And I caught my Lab/Great Dane in the act, he won't even look cross ways at a chicken now.
http://www.theeasygarden.com/forum/viewtopic.php?id=35617
There are dogs with such strong prey drive that they can never be trusted around poultry. They just have to be kept away from the birds.