I know this is about yellows, but when we went to the St Louis Zoo they had this MASSIVE green, and they said she'll only take a pig once a month, and refuses any other prey items. Didn't mention what size, mind you, but this girl was HUGE, probably bigger around than my entire body at her widest point. So, pigs are probably also an option for yellows as well.
(I have a pic of this girl if anyone wants to see it lol she was my favorite)