My chicken guardian was a barbados sheep ram. We hand raised him from a lamb and fixed him young so he didn't get too aggressive but he did hang out with the chickens and he would run off anything getting near them. Our miniature horses pretty much did the same thing too but they will also nip at a chicken if they think it's too close to their food where as the sheep would share his food dish with the chickens. Having known my dogs, even my herding breeds I wouldn't have trusted them with chickens. In fact my neighbors dog was a LGD (goats) and when it came into our yard it killed my Polish hen Somba I use to have, my dogs killed ducks, and another smaller dog ripped tail feathers out of our RSL hen Tiki. I did catch my sheep Laces once driving off a little Pomeranian who was chasing my RSL hen Tiki though. He head butt the little sucker and sent him rolling. The dog went yipping off back to his yard. Apparently he had dug out of his back fence but never came into my yard again. I never had a predator problem while I had my sheep and actually my chicken didn't get eaten until after he had passed away from old age. I'm thinking of getting another ram or buck as soon as I get new chicks and what luck one of my coworkers pygmy goats just had twins, both boys. Here's hopping one of them is my new 'chicken guard.'
Also some people would say sheep/goats probably wouldn't bond with poultry but since they are social creatures when raised solo they attach to other social animals, mine was attached to my miniature horses and hen. In fact it wasn't rare to see the hen sitting on his back during the day and 'riding' on him and he always followed her around the yard. When he passed away the hen attacked us when we tried to move his body out of the barn and she was laying on top of him pecking at his ears and talking to him (he passed in his sleep so he looked like he was still just sleeping). It was really sad. Anyone else have good luck with sheep, goats, or miniature horses or donkey's as good poultry guards or did I just get lucky with my Lay Lay boy?