Eventually I try and get everything eating frozen thawed rats but most won't start on f/t. I try a feeding or two and then try live mice and/or rats. Some years I seem to have better luck but most of the time very few will take f/t for their first feeding. They seem to prefer hopper mice but some will take rat pinks. After a few live meals I'll start trying to switch them over. Once they have fed a few times it's pretty easy in most cases.