Depends on the size of the ball. Its amazing what they can eat, however you should offer them a meal about as big around as the fattest part of their body or roughly 15% of their body weight.
That said, we have a 3,300g female that would have no problem eating even the largest rats. She would also have no problem eating an adult guinea pig or small rabbit. She would be on large rats if she would take them. She only wants to eat sm/md rats, which is fine with me. I have no problem giving her two to three at a time to make up for it.