Predators and Sheep

In October 2013, I attended the annual Sheep & Wool Festival in Rheinbeck, New York, and there were many people there who keep sheep, mostly from the rural Northeast. Most of them were female, and many minded the sheep in their stalls, while spinning wool using manual wheels. the sheep themselves seemed to accept all with equanimity, sometimes enjoying petting or treats, but usually not greatly aware of the crowds passing among the stalls where they were quartered.
I asked many of the sheep farmers about predators, and every one had to contend with coyotes, wolves, bears, and mountain lions. Not a single farmer wanted to eliminate predators, or even got excited about them. They generally use a combination of electric fences and dogs to protect the sheep, and one told me that predators are not very persistent. If there are a few obstacles, predators generally prefer to expend their energies elsewhere.
Some sheep farmers observed that the sheep themselves are not always so helpless. One had seen rams face down coyotes and wolves. The rams would stomp and lower their horns to charge, and the predators would back off. A few sheep farmers also kept lamas with the sheep, and said they also are pretty effective defenders. Yet another sheep farmer remarked that once the infrastructure to protect the sheep is in place, keeping predators away is not difficult.
One more told me that the greatest threat to sheep was from domestic dogs, since they will kill many sheep but not eat them. They, apparently, retain a hunting instinct, but do not think of prey as food.