We raise and sell imported working-show class lines of German Shepherds,,
http://www.vomlauterbach.com and with the German Shepherds we raise,titles are invlolved.More so in Germany,but the reason behind titiling a German Shepherd, is to prove they still have inherited instincts,such as protecting,agility,and prey drive.
If these dogs were still not domesticated,they would be required to hunt and kill for food,for themselves and their pups.Any good German Shepherd will be able to scent track,and should show no fear in protecting(as in it's pups) or to kill for feeding. Another strong part of the German Shepherd is being under the control of the handler at all times,,this shows the dog still responds and obeys basic commands.
You can train this breed to leave certain other animals alone,but it takes strong,and concise repitition,done each day and done the correct way.They say German Shepherds are "strong willed" which is a very polite way to say they are hard headed.If your dog will chase after a ball when thrown,or a frisbee,it does have drive,but if it shows little or no interest in going after objects,then I would not put much worry into it about the dog chasing the chickens.