I've had better success with the small rats. I had bought a bag of med rats from rodent pro but my female would eat one, then not eat for a couple of weeks, so i started feeding just small rats and I haven't had a refused meal since and my guys are growing like weeds now. Better a slightly underfed snake that will be hungry and have a strong feed response everytime food is offered than an over fed snake that is going to fast and cause you stress.