I have a lab/BC mix and I trained him with the "my chicken" method also. A dominant voice and posturing is a good start for a smart dog. I use the roll and shake of the scruff ala Cesar Milan method and a strong, "MY CHICKEN" for this pup. No dog could have a stronger prey drive than this dog, with several kills to his credit of coon, groundhog, songbirds, moles, mice, etc.
I free range chickens and chicks of all ages, at all times, without one incident from this pup in the past two years.
It CAN be done. With a smart dog and an alpha dog owner, it can be done. I've had no incidents whatsoever with this dog or my older lab/GP mix....who I didn't have to train at all. She just naturally leaves anything that belongs to me alone....be it cats, chickens, cows, etc.
For every story about someone's pet dog eating their chickens, there is a hundred other stories that you do
not hear about someone's dog NOT killing their chickens. The reason you do not hear them is because there would be no reason to post it each and every time, every day, every moment that this happens. And there is really no drama connected with a dog doing his job of protecting his owner's property, so no one would be really interested in this type of thread.
Every dog I've ever had was either a lab or lab mix and each and every one has never killed, maimed or even come close to putting his/her mouth on a chick, chicken, kitten, bunny, etc. Its not luck, its intelligence and expectations of both pet and owner. A working partnership between these two creatures is not luck....its been documented down through the ages and has been a good thing.
Try it, constantly monitor the results of your training, measure effectiveness and then, when its been achieved, sit back and relax....enjoy both your animals living together!