Ah that looks like the answer to my question right there.

"They slow down their food intake once mature and almost full grown."
I thought it was silly to think that I would have to feed him a absurdly gross amount of worms when he got bigger. Haha, I would assume the process of slowing down their food intake is a result of being at their peak fitness, no longer needing the nutrients from their food as their growth declines.

As for the sausage casing I would imagine my frog would need to be thoroughly tong trained in order to get him to consume it, or try to get a long sausage chain and trail it around in front of him? :P Sounds like a fun idea.