I am not aware of any chart of essential amino acids and vitamins that tarantulas cannot synthesise from raw components, or that there is any relationship between the proper diet of a given prey item and what is actually in that prey item.
For example, we can't synthesise vitamin C, so we need to eat foods rich in vitamin C but other animals animals and plants synthesise their own Vitamin C just fine. The nutrients found in something has little to do with what something eats (assuming their proper diet) but what that something actually utilises within their own body.
They are an adition to the diet, as apposed to the main constituant.
Thicker cuticle, slimmer bodies and fewer nutrients...though i cant back taht up to say that im sure the research has been done, as we all use crix or roaches for their highly nutritious innards as the man diet.
Personlally i will feed as much a variety as i can muster to my T's. I feel they live long enough to concern myself over diet through-out there lives. *pretty much all invert diet* locusts are the second main constituant, being fed a couple every month or two.
Just like with tortoise, its an on going practice to make sure to have the right diet.. they live for in excess of 1hundred year and what they eat now- tuil then can have detrimental affects and stunt pretty much every aspect of them. more than likely stuntingthere lifespan.
Ofcourse Ts live much shorter, but long enough.
I hope that makes sense.. tho it might be a lil sidetracked, lol