Yes, sheep droppings - dogs love 'em
When we lived on the outskirts of a town we had a neighbour's dog which would raid our cat litter tray - he just loved cat poo rolled in cat litter
I think he was simply deranged because all he was going to pick up potentially was parasites - lucky for him we wormed our cats regularly.
As well as a nicely shaped sheep dropping, our dogs love their foot clippings too
I'm sure that as Sally says the dogs are getting nutrition and fibre from the sheep droppings, although ours eat grass and couch roots too occasionally. Cooked vegetables ie leftovers, added in to their dinner might help, if you don't like the post-poo-eating-session dog breath
Dogs eating dead things is always a worry in case they have died of poison which is still active in the corpse and could poison the dog. Ours only like to chew on really ancient dead vermin which have turned into frisbees. Three day old dead crows, deer etc though are wonderful to roll in