your experiment has been done with red eared sliders that i know of , the result i remember was the uvb supplemented group had on average twice the blood level of d3 ....... as far d3 , it's my understanding plants are poor sources , the best sources are animals that produce it themselves , and to get significant absorbtion from dietary d3 i'm fairly sure it requires fat is consumed with it ........... one thing i've seen over the years is turtles and tortoises can persist under much less than ideal conditions for years ..........Hopefully I will get a few hatchlings from my next clutch, then the intention is to run 2 identical enclosures, one with a uvb strip light at the lighter end of the enclosure and one with a normal strip light(no uvb) at the lighter end of the enclosure. Everything else the same.
2 questions.
1. To what sort of age have you grown hatchlings to without any real or artificial UVB source.
2. You don't feed animal protein until they are 6 months old, where do they get the D3 from during this first 6 months? I can only assume it's mushrooms and maybe there is some vitamin D in the original eggsack that lasts out this period.