I get the little packets of alphabet pasta shapes from Rat Rations and use them as part of their base diet. Rupert will get 2-3 whole ones and Joey 1 crushed one every time I change their food bowls (every three days or so). I never really considered that it might be too much - pasta is only egg and flour so I didn't think it'd be a problem and the crunchiness would help their teeth.
I may cut back to just an occasional treat though
