I am having a similar problem with my girl she is right around 400 grams and I wanted to make the trasition from live mice to FT rats. I figured I would transition to live rats first to make it easier. She was nailing small mice every 5 days without hesitation. When I tried to feed the first rat she was just starting the shed process and would not take it so that did not suprise me. She ate it 7 days later. 7 days after that I tried another live rat and she refused again, so I figure I will try that one next weekend again. I am feedig rats around 40-45 grams so they are the same size as the mice I was feeding and when she took the first one I figured I had it beat. With the size I am feeding I hope she starts taking them every 7 days because they are small enough every 14 days does not seem like enough.