Abstract
Bioavailability of α-tocopherol varies with source, dose and duration of supplementation. The effect of source and dose of α-tocopherol on response of α-tocopherol stereoisomers in plasma and tissues of mink kits during the weaning period was studied. Twelve mink kits were euthanised in CO2 at the beginning of the experiment, and 156 mink kits (12 replicates per treatment group) were randomly assigned to thirteen treatment groups: no added α-tocopherol in the feed (0 dose) or four different doses (50, 75, 100 and 150 mg/kg of diet) of RRR-α-tocopherol (ALC), RRR-α-tocopheryl acetate (ACT) or all-rac-α-tocopheryl acetate (SYN). Six mink kits per treatment group were euthanised 3 weeks after initiation of the experiment, and the remaining six were euthanised 6 weeks after initiation of the experiment. The RRR-α-tocopherol content in plasma, liver, heart and lungs was affected by interaction between source and dose (P < 0.01 for all). The highest RRR-α-tocopherol content in plasma (13.6 µg/ml; LS-means for source across dose and week), liver (13.6 µg/mg), heart (7.6 µg/mg) and lungs (9.8 µg/mg) was observed in mink kits fed ALC. The RRR-α-tocopherol content in plasma and tissues depended on source and dose interaction and increased linearly with supplementation. In conclusion, the interaction between source and dose reveals a limitation in hydrolysis of ester bond in α-tocopheryl acetate in mink kits around weaning as the likely causative explanation for the higher response of ALC at the highest doses. Thus, considerable attention has to be paid to the source of α-tocopherol during weaning of mink kits fed a high dose of α-tocopherol.
Highlights
Bioavailability of α-tocopherol varies with source, dose and duration of supplementation
Hydrolysis of the ester bond in α-tocopheryl acetate is facilitated by pancreatic carboxyl ester hydrolase and may be the limiting factor in the absorption of α-tocopherol in young farm animals, such as newly weaned piglets and calves[2], and in individuals with impaired lipid absorption c apacity[4]
Hydrolysis of the ester bond is not considered to be a limiting factor for absorption of α-tocopherol during weaning in mink in diets containing 65 to 70 mg/kg of α-tocopheryl a cetate[3]. It remains unclear whether the hydrolysis capacity of α-tocopheryl acetate becomes a limiting factor at higher levels of vitamin E doses in the diets
Summary
Bioavailability of α-tocopherol varies with source, dose and duration of supplementation. The effect of source and dose of α-tocopherol on response of α-tocopherol stereoisomers in plasma and tissues of mink kits during the weaning period was studied. Hydrolysis of the ester bond is not considered to be a limiting factor for absorption of α-tocopherol during weaning in mink in diets containing 65 to 70 mg/kg of α-tocopheryl a cetate[3] It remains unclear whether the hydrolysis capacity of α-tocopheryl acetate becomes a limiting factor at higher levels of vitamin E doses in the diets. The purpose of the present experiment was to investigate the effect of stereoisomeric configuration, free or acetylated form of α-tocopherol at different doses of supplementation on plasma and tissue responses as well as bioavailability of RRR-α-tocopherol in mink kits during the weaning period. Last sampling was at 10 weeks of age (6 weeks after administration of α-tocopherol)
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