Interesting study and implications for coop/run design: Increasing vitamin D in chickens/eggs

[TooCheep]

@raingarden - Understood. As I stated in the OP, you have to do the best you can in your individual circumstances. Getting more light access is just one factor in your setup and may lose to other requirements- cost, security, etc. At least you don't have the short days that many of us have in winters.

 

[saysfaa]

 

[Krugerrand]

Apparently mushrooms Vitamin-D content can be boosted by exposing them to UV-B:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6213178/

4.4. Fresh Mushrooms Exposed to UV Radiation from Lamps​

An efficient way to produce nutritionally relevant amounts of vitamin D2 is to expose mushrooms to specific, controlled levels of UV radiation via a fluorescent UV lamp or a pulsed UV lamp. Mushrooms will generate vitamin D2 in response to exposure to UV radiation both during growing phase and post-harvest; however, commercial growers use UV lamps post-harvest for practical reasons. Fresh mushrooms, when deliberately exposed to a UV radiation source post-harvest, will generate significant amounts of vitamin D2 often reaching 40 μg/g dried mass (DM) (ca 320 μg/100 g FW) [11,15,17,36,40,41,42,43,44,45]. The most effective wavelength to stimulate the production of vitamin D2 in mushrooms is UV-B radiation (280–315 nm) [43]. Some researchers have used UV-A (315–400 nm) [34,43,46,47] and UV-C (<280 nm) radiations [15,34,36,43,46,48,49], however UV-A radiation was not effective at increasing vitamin D2 concentrations in all cases [34].