Effect of large dietary doses of ß-carotene on plasma retinoid AND ß-carotene levels and ON progesterone production in the granulosa cells of Japanese quail
An experiment was conducted to study the effect of large-dose (-carotene supplementation on blood retinoid and (-carotene levels as well as on the progesterone secretion of the granulosa cells in Japanese quail. Laying quails were assigned to three dietary groups. The control group
(Group C) received the basal diet (laying feed containing 9000 IU vitamin A/kg). In the treated groups (Groups BC1 and BC2) the basal diet was supplemented with 102and 103mg/kg (-carotene (BC), respectively. At the end of the two-week feeding period, 10 birds from each group were euthanised.
Blood samples were analysed for retinol, retinyl palmitate and (-carotene concentrations. Granulosa cells were isolated from ovarian follicles (F1and F2), and PMSG-inducedin vitroprogesterone (P4) secretion was measured. Similar retinol concentrations were found in both (-carotene supplemented
groups, indicating saturation of the retinol-transporting system. (-carotene supplementation was accompanied by hypercarotenaemia, but did not increase the retinyl palmitate levels in the blood. PMSG-induced P4production of the granulosa cells decreased significantly in Groups BC1 and BC2
in a dose-dependent manner.