silkiefan - all good points! especially about showing them the chicks - i'd add to make the dog sit or 'down' and hold the chicks above them - dogs understand a physical hierarchy.
you can also search on the command "leave it" or i use "thats mine" and use this in all situations that you have your dog. for instance, give them toys to play with then randomly walk over and say 'thats mine' or "drop it" or "leave it" - take it then walk away. do the same with food - after giving them a bowl of food walk over and take it from them.
DO NOT EVER EVER EVER PLAY TUG OF WAR WITH YOUR DOG EVER
this is not a game to them - its dominance behavior. the dog will learn that you 'own' everything. when you take the toy/food/whatever make sure they dont bounce around or 'test' you to get the toy/food or whatever back. they should not paw at you (say "NO!" sharply) or wag all around or spin in circles or try and muscle you. work your way up to taking the toy/food walk a short distance, put it down and when Mr Woofy bounces up to it - say 'thats mine!" or "leave it!" and make them walk away from whatever it is. make sure whatever you give them they GENTLY take it from you - not snatch it away.
because we have such big dogs - and oh about a million cats - we also maintain 'dog space' in our house - dogs can NOT roam around or get up on the same level we are (in the bed, on the couch). i dont ever wrestle with them, they may not 'mouth' on me or play bite, or push or shove. you should be able to stand over your dog, one foot on each side of him - and he should NOT wiggle around or push you off. the Monks of New Skete have an amazing training exercise where they make all their GSD's 'down stay' in a row - and one of the monks steps over each dog.
dogs also have to sit quietly by the door and not shove ahead of us when we walk out - honestly walking out ahead of them really works! they understand that i set the tone for their behavior.
they need to see you as the boss and they are more than happy to follow the boss. the hard thing - and what i think frustrates a lot of people - is that dogs are 'social climbers.' they are always trying to be the 'top dog' which is why they will act up. you need to be the boss of them every single day, every single moment. that doesnt mean you have to be cruel or harsh...they just need to know that you are the boss. when our dogs have 'ants in their pants' and act up - or dont listen - we exhaust them with exercise, work them more, then exhaust them again. a tired dog is a good dog.
we keep them alert and engaged with new jobs or commands. the best advice i ever got was to move from verbal commands to hand signals - which i use most of the time now. if i could whistle i'd use that as a tool.
know too, that this takes a LOT of work. if your dog naturally is good with livestock - great! but dont every underestimate their prey drive
good luck! and pm me if you need more help with where to find training info