All-rac-α-Tocopherol Acetate Is a Better Vitamin E Source than all-rac-α-Tocopherol Succinate for Broilers

Abstract

The difference in bioavailabilities of the acetate and succinate esters of all-rac-α-tocopherol was investigated in a feeding experiment with broilers. The experiment was initiated with 96 12-d-old male Cobb broilers and lasted for 4 wk. The two sources of vitamin E were fed to eight groups of broilers at four different dietary levels (50, 100, 150 and 200 mg/kg feed, including the naturally occurring α-tocopherol). A total collection of droppings for determination of apparent tocopherol absorption were performed at two separate time periods (d 28–34 and d 35–41). There were no differences among the eight experimental groups with respect to animal performance or feed intake. At all dietary levels, the apparent absorption coefficient for all-rac-α-tocopherol succinate was significantly lower than that of the acetate ester. The mean (± SD) apparent absorption coefficient for all-rac-α-tocopherol succinate was 58.0 ± 5.4 compared with 70.8 ± 5.6 for all-rac-α-tocopherol acetate. Furthermore, the apparent absorption coefficients for both esters was significantly lower in the first collection period (d 28–34) than in the second collection period (d 35–41). This difference in the apparent absorption coefficient between the succinate and the acetate ester was accompanied by significant differences in α-tocopherol concentrations in plasma, breast muscle, liver and adipose tissue of the broilers, which were lower in those fed the succinate ester. Based on a comparison of plasma and tissue responses, the succinate ester was utilized only 69–76% as efficiently as the acetate ester. In vitro studies showed a significantly higher capacity of pancreatic carboxyl ester hydrolase to hydrolyze α-tocopherol acetate compared to α-tocopherol succinate. This difference in intestinal hydrolysis of the two vitamin E sources may explain the observed differences in biopotency.