by nixity on 07 Feb 2010, 10:27
Let's not forget that Wikipedia is edited and content added by individuals, not necessarily referenced or always accurate.
The idea that blue gouldians can not produce their own Vitamin A has never been documented or proven.
From everything I have read, they are basing this off the White/Albino canaries which seemingly can not manufacture Vit A in the body.
The logic behind it is that a blue gouldian, genetically, can not produce "carotene" pigments which is what makes the bird visually blue. Ordinarily, the presence of lutein absorbed from foods results in a yellow color that visually mixes with the base melanin and structural blue in feathers resulting in the "green" body color we see.
A blue gouldian is the result of an inability to process lutein (a carotene color) and the bird ends up looking visually blue as a result.
However - carotenes are not completely blocked because we still see a reddish/orangeish color expressed in the head. It is only partially inhibited, not completely.
So the assumption is the entire metabolic pathway is effected, but unless it's research, it is all just that - an assumption.
There have been cases of lutino cardinals (the carotene that results in the "red" color cannot be processed in the body, so the bird appears yellowish) and the metabolism of Vitamin A was not affected - just the deposition of the pigment itself.
So, to me, it is entirely likely that in a blue gouldian the only thing affected, again, the actual pigment deposition and not the entire metabolic pathway (beta carotene is converted to vitamin A in the small intestine, but this is only one way Vitamin A can be obtained).
If it IS true, a vitamin A supplement in the form of a powder will not be sufficient.
It has to be a PRO-vitamin A which has to come in the form of an animal protein - and this is usually accomplished by adding Cod Liver Oil to seed or egg food.
Personally, I have never supplemented my blues with Pro-Vitamin A and I have never seen any adverse health effects as a result.
Let's also not forget that Vitamin A is fat soluble and it's easy to give birds TOO much causing hypervitaminosis.