A rapid bioassay for the comparison of xanthophyll availability from various sources

A rapid bioassay method for comparing xanthophyll availability from various sources or the pigmenting ability of genetic strains or crosses is proposed. Xanthophyll depleted, fasted birds are intubated with equal amounts of xanthophyll from various sources. Serum xanthophyll is then determined from blood samples obtained 14 to 24 hr following intubation. Results are expressed as the increase in serum xanthophyll (microgram/ml) over the intubated controls per milligram xanthophyll intubated per kilogram body weight. Limitations of the bioassay are discussed.