I havent heard anything on the gut loading thing but I have heard that there are things you could feed the rats that could be harmful to snakes but I am not positive as to the truth behind some of the claims. I have heard things with dies in them like some dog foods are not good for snakes and then I have also heard that some seedy foods that the rats eat can be harmful to the snakes. Not sure if they are true but I stay away from things that have this just to be safe...