Certainly not ALL coyotes are calf killers, BUT it seems that those that learn to do it, keep doing it until they pay the ultimate price for it.
I know a farmer in KS. that would never let coyote hunters on his property until he had an incident where he caught the coyotes in the act of killing a calf. It happened at night, and he heard the cow raising cain out in his pasture, so he went to check on it and found that the coyotes hadn't killed the calf yet, but had already started on it, stripped its tail and had bite marks on the hind quarters, and the cow was so worked up that she wouldn't hardly let the farmer near the calf. BUT the farmer took the calf to the house to doctor it and keep it in the house over night and planned on taking the calf back to the cow in the morning. Well, when he went out the next morning, he found the cow dead and partially eaten.
Not one coyote does such a thing, but a pack of them can handle full grown cows, deer, etc. He called my cousin that very day and when we hunted his home section and three adjoining sectionswe caught 7 coyotes with the grey hounds. Didn't catch all that we saw, BUT he never lost another calf that winter and we get to hunt his land every winter now.