So what do you call a group of horses asses?Maybe this helps as to what to call a group of horses? To me, either "herd" or "string" would be the correct term for a group, although for the most part, I've used herd.
"What is a herd of horses called?
Question: What is a group of horses called? Answer: It is alternately called a team, a harras, a rag (for colts), a stud (a group kept primarily for breeding), or a string (a group belonging to or used by one individual)."
congress? Hollywood?