My GSD got ahold of two of my birds when he was 11 months old. I thought he had good recall, but didn't test it under distraction and didn't realize the chickens had wandered to a place where he could get them. He couldn't resist an interactive toy. I had to put one down, and my poor rooster will never grow tail feathers again.
While the dog is much better now thanks to more training, I never have, and never will, fully trust a dog around a chicken. They can't help the prey drive. That's why I use the electric poultry fence from ground thaw to ground freeze up. The above incident happened when the ground was still frozen and I thought I'd let the chickens stretch their legs behind the barn on a beautiful spring day instead of confined to the run.
I grew up on a small farm. From time to time, livestock will die. It just happens. There will be the occasional loss to wild and domestic predators, calves that are stillborn, chicks that fail to thrive, sows that roll on a piglet, rabbit kits that get out of the nest, goats that get their heads stuck in the eave of the shed, illness, etc. Its a fact of life I have to accept even though I don't like it.
Most of our livestock were raised for food, so they weren't going to die of old age anyway, and it makes no sense to get emotional if an owl gets a chicken a week before it was scheduled for the chopping block. It just sucks to lose out on the dinner you put time and money into raising.