Humans and many other mammals are omnivorous. With supplementation, we can live on either plant OR animal, but without supplemental vitamins and minerals, one or the other is not enough to remain healthy. I'm not a doctor, but have spoken to enough doctors out there to believe that is accurate. I suspect serpents don't have the intelligence to get tired of one thing only, but I've tried Adkin's low carbohydrate diet and don't think I could do that religiously for the rest of my life.
Snakes were never meant to live on meat alone. Meat being the muscles of other animals. They require roughage, vitamins and minerals found in the viscera, skeletons, and even fur of their natural prey. Just the muscles of mammals is not enough. Even the stomach contents of their prey contribute to a snake's nutrition. It's OK to occasionally feed them just meat, but that should never be their staple diet and if you feed them too much, there'll likely be no warnings of impending malnourishment. They'll just die. No do-overs then. Remember also that you're giving them too much bacteria and too many parasites in raw meat. I lost five pounds the first month of taking parasitology in college after finding out what I've been eating all these years.
It's always best to follow Mother Nature's lead and feed them what they get in the wild. There are no successful substitutes on that level that I'm aware of. However, if you ever develop a line of vegetarian snakes, you'll get the attention (and $$) of thousands of snake keepers.
Good luck,
Don Soderberg
South Mountain Reptiles
www.cornsnake.NET
South Mountain Reptiles