I didn't know that a 'superfood' diet can cause problems in eclectus. I did know spirulina was a no go because I've been stalking this form for awhile. I'm glad I know now though because I was planning on feeding mostly nutrient dense veggies like microgreens (I grow them for myself anyway) and sweet potato. Today I found out my breeder does vaccinate against polyoma. Apparently it's the standard now in the US. It probably wouldn't be in Australia though given their strict laws on making sure exotic birds aren't imported there.
For full spectrum lighting, you should try lights meant for humans. They are doing the same thing, don't buy into marketing hype of bird UV lights. If you want the full chemistry breakdown of vitamin D uptake, I don't mind putting my degree to actual use here but for now I'll give the basic. Mammals and birds use the same chemical pathways to synthesize vitamin D. You can give Vitamin D2 foods as much as you want but without light they never convert. Light is necessary if you want to truly activate and convert the vitamin D2, but vitamin D3 is already converted so it isn't as necessary for that. If your supplement says D3 then you don't need to worry as much about light in theory (in practice is another story). The active form of vitamin D (D3) is only found in animal products because it was previously synthesized when that animal was living. This is why vegans have a tough time finding some supplements.
Then there's the problem of absorption. The absorption rate of D3 is incredibly tricky in humans, as it's controlled by a variety of factors, but as I said birds use the same chemical pathway so we can make some assumptions about them based on research done on humans. In saying that, you can pretty much bet that your Australian birds are going to have a more difficult time absorbing vitamin D3 that it did not specifically convert itself. This is because Australia has a stronger sun and therefore much quicker and efficient vitamin D2 conversion. This is also why aboriginal people in Australia are so dark in skin tone, they did not need any help in converting vitamin D2 like white people did in England. Native Australians evolved for lots of sun, and Australian birds had to do the same. As evolution does not give advantages to those who don't need it, Australian birds wouldn't have needed to take D3 in from animal products when converting D2 was so easy. Australia in particular is known in my field (evolutionary biology) for it's unique take on evolving organisms. Australian animals are more likely to highly specific diets (think lories and koalas) and aren't as adaptable to changes in their environment or food source. This is probably why vitamin over supplementation is so risky for eclectus. However, you should be able to avoid over supplementing with the use of light therapy and D2 naturally available in food. Your bird's body should simply stop converting when D3 levels are where they should be. The same could be said about vitamin A, if it's given in beta-carotene form. This is called the 'provitamin advantage' and it's actually the reasons doctors warn against vitamin A supplements but have no problem with you eating sweet potatoes and carrots by the pound.
If you guys are interested I could write something up on nutrient co-absorption. Meaning which nutrients inhibit the absorption of others and which boost the absorption of others. I'm studying it anyway as part of my masters.
