I feed all my balls on the same day. So, what I do, is take out however many rats I need in the morning and let them set in the snake room all day long to defrost. Then, at night, I put them in hot water for about thirty minutes. Haven't had a problem so far... though I have one ball who s incredibly picky... if I set the mouse in front of her and it's too cold, she turns her nose up! She won't take it til it's the temp she wants.