If the bike chains used are anything like mine, they would be pretty easy to get through.
They are big, fat links that fit each other quite closely, so if they fit the hole fairly well should just push straight through, and a lot of bike chains are in a cloth sleeve as well (to protect the paintwork).
but as rust would course expansion and break the concrete (slowly) they will last a lot lot longer plus better electrical connection for the sheep fence to keep the little buggers under control