β-Carotene, Retinol and Retinyl Ester Concentrations in Serum and Selected Tissues of Ferrets Fed β-Carotene

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Abstract
The concentrations of β-carotene, retinol and retinyl esters in serum and selected tissues of ferrets fed diets supplemented with β-carotene (80 µg/g wet diet) for 3 wk were determined. The initial concentration of serum β-carotene was 0.011 ± 0.006 µmol/L (mean ± SEM); at the end of the experimental period it was 5.75 ± 1.60 µmol/L. No significant differences in serum retinol and total retinyl esters were observed between β-carotene-fed and control ferrets that had been fed an unsupplemented diet. The predominant retinyl esters in serum were retinyl stearate (53%) and retinyl palmitate (35%). Of the tissues analyzed after β-carotene feeding, the liver contained the highest concentration of β-carotene (78.8 ± 18.8 nmol/g). Other tissues that contained β-carotene in amounts ranging from 17 to 20 nmol/g were adrenals, small intestine, stomach and colon; lesser amounts (6.9 nmol/g) were found in kidneys. Amounts ranging from 1.2 to 2.3 nmol/g were found in muscle, bladder, adipose tissue, lungs and skin; only 0.37 and 0.34 nmol/g were present in brain and eyes, respectively. Thus, like humans, ferrets have the capacity to absorb intact β-carotene and to store this compound in tissues, especially the liver. However, compared with humans, ferrets have elevated concentrations of retinyl esters in serum, liver and other tissues.