Utilization of dietary β-carotene and retinol acetate by goslings and young geese

One-day-old and 3-month-old geese were fed different concentrations of beta-carotene (5, 10, 50 or 150 mg kg(-1) feed) or retinol acetate (10 000, 20 000 or 40 000 IU kg(-1) feed) for about 3 weeks to assess their ability to convert beta-carotene to vitamin A. Blood serum concentrations of beta-carotene, retinol, alpha-tocopherol, triacylglycerides and cholesterol, as well as liver concentrations of beta-carotene, retinol, triacylglycerides and cholesterol, were included as response factors. beta-Carotene was not detectable in serum and liver. Serum and liver retinol concentrations were positively correlated with dietary concentrations of beta-carotene and retinol acetate (R-2 = 0.84 and 0.95, respectively). In goslings 1 mg of beta-carotene corresponded to 63 IU retinol and in young geese to 1216 IU, equivalent to 3.8% and 72.9%, respectively, of the theoretical value of 1667 IU retinol. Cholesterol concentrations in blood serum and liver were not affected (P> 0. 05) by the dietary levels of beta-carotene and retinol acetate. The concentration of alpha-tocopherol in blood serum decreased with increasing dietary levels of beta-carotene and retinol acetate. In the goslings the concentration of triacylglycerides in serum and liver was significantly (P<0.05) influenced by the intake of beta-carotene, but not by the intake of retinol acetate. In the young geese the serum concentration of triacylglycerides decreased (P<0.05) with increasing dietary levels of beta-carotene, but was not affected by the dietary concentrations of retinol acetate. The concentration of triacylglycerides in liver tissue of young geese was not affected by the dietary concentration of either beta-carotene or retinol acetate (P> 0.05).