Effect of polarity on absorption and accumulation of carotenoids by laying hens

The effect of carotenoid polarity on absorption and pigmentation in laying hens was measured by a 6-week feeding trial using 50–300 mg carotenoids/kg feed. The order of carotenoid polarity used in this study was β-8-apo-carotenoic acid ethyl ester (ACAEE) > canthaxanthin> β-carotene. ACAEE and canthaxanthin were absorbed 9–11- and 3–5-fold more into the blood than β-carotene. Translocation of β-carotene from blood to skin was 2–5-fold higher than those of ACAEE and canthaxanthin. This result indicated that the higher the polarity, the more the absorption of carotenoids into blood but the reverse was true in the case of translocation from blood to skin. In skin, the yellow carotenoids, β-carotene and ACAEE increased yellowness (b values of colorimetric measurement) and the red carotenoid, canthaxanthin, increased redness (a values of colorimetric measurement). However, in breast muscle only polar ACAEE significantly (P < 0.01) increased b values. Polar carotenoids, canthaxanthin and ACAEE affected egg-yolk colour within a week but β-carotene did not. The results indicated that the polarity of carotenoids affected the absorption into blood, the deposition in fat tissues and the colour of egg-yolk.