Is it true...

I have read tha mice are better than rats for your snake. Is that true? The reason stated is that mice are healtier due to rats having more cartilege. IDK but if I switch to all mice, even large ones, my biggest snakes would probably eat 4 at a time. Which is not a problem if that is whats best for them. Any opinions?

Rodentpro's website has an article entitled "Nutrient Composition of Whole Vertebrate Prey."
http://rodentpro.com/qpage_articles_03.asp

You can see that adult mice have 55.8% protein, 23.6% fat, and 2.98% calcium. Adult rats have 61.8% protein, 32.6% fat, and 2.63% calcium. So, rats are higher in protein and fat, but lower in calcium. BTW, I'm mentioning calcium because I guess that might be what your friend was getting at when he mentioned cartilage, although I would think bones, not cartilage, would be highest in calcium.

Anyway, as far as I am aware, there have been no scientific studies on the nutritional requirements of ball pythons. So whether that higher calcium is good, bad, or just doesn't matter, we don't know. I do know that lots of captive snakes of many different species are kept on a diet of rats for their entire lives, just changing the size/age of the rat as the snake grows, and they seem to do just fine on it. I, and plenty of other people, feed mice, increasing the number of mice fed per feeding as necessary. And of course there are some who feed a mix, or feed ASFs, or some other rodent. Most snakes seem to do just fine on these diets, even those that don't naturally eat rodents in the wild, or perhaps eat rodents as well as other things.

So, there really isn't a definitive answer to your question. Feed what works for you and your snakes.

That is exactly what I was looking for! Thanks a million! Also thanks for posting the site, I will keep that around!