Among the B-vitamins groups are only the riboflavin (Vit.B2) and the folic acid of yellow, yellowish to slightly orange color. But these chemical yellow components are completely metabolized after eating and are no longer yellow after the action of gastric acid and at the latest when passing into the anterior small intestine. After that process they get into the blood. Even if the natural yellow color component were retained, B-vitamin storage in the plumage is not biochemically possible, only melanin, carotenoids and porphyrin can be stored there.