All-rac-alpha-tocopherol acetate is a better vitamin E source than all-rac-alpha-tocopherol succinate for broilers.

The difference in bioavailabilities of the acetate and succinate esters of all-rac-alpha-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 alpha-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-alpha-tocopherol succinate was significantly lower than that of the acetate ester. The mean (+/- SD) apparent absorption coefficient for all-rac-alpha-tocopherol succinate was 58.0 +/- 5.4 compared with 70. 8 +/- 5.6 for all-rac-alpha-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 alpha-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 alpha-tocopherol acetate compared to alpha-tocopherol succinate. This difference in intestinal hydrolysis of the two vitamin E sources may explain the observed differences in biopotency.