Hello! I'm new here this is my first thread. I'd like to know whether C02 or liquid nitrogen is the most painless way to kill a rat to afterwards freeze it. I've read a lot about CO2 being the most 'humane' way to kill them until I fell on a comment that said something about liquid nitrogen. Apparently liquid nitrogen knocks the rats out without them even noticing and then kills them compared to CO2 that suffocates them to death wich causes them pain. I'm wondering how each product works on the rat (do they really get knocked out? do they feel any pain?) and how long it takes for them to die. Does one way cost much more? Let me in on all the info you have about N2 and CO2! Thanks!