Sheep are not work animals.
Sheep are not pets.
Sheep may be eaten.
Sheep may be fleeced.
Having had the unfortunate job of working with sheep I can also say that sheep, in general, are stupid. If they are not dead they are looking for a place to die. If they become caught in a fence they will just lay down and die on the spot more often than not. Trying to doctor an injured sheep or otherwise care for it usually results in it up and dying. Seems like the perfect animal to liken JW's to.
But then again on the other hand I was raised in cattle ranching country and hate sheep with a passion.