I'm sorry for your loss. I hope the electric fence is working well. But, I think you know that training is still essential!
Basic obedience
should not even be an option for any dog owner! you need to get him to learn "LEAVE IT". If he goes in the direction of a chicken, "leave it" should change his direction.
And let me tell you-that "if the dog gets a taste of blood he'll never stop killing" IS NOT TRUE!
My mastiff is raw fed-80% chicken! He will pounce at them when he is eating but he will not hurt one.
Best of luck to you and your dog,
~~It is the resposible pet owner that sees problems through and doesn't just "whack" the offender!
Your a good dog and chicken mommy!