Tocopherol absorption and metabolism in the chick and turkey.

Chickens and turkeys were fed from hatching basal diets to which tocopherol was added at levels of 10, 50 and 250 mg/kg for 28 days. During the last 4 days [3H]tocopherol and 141Ce were included in the diets. Plasma and liver tocopherol levels were correlated with dietary tocopherol in both chickens and turkeys, but concentrations were 1.5- to 4.5-fold lower in turkeys. Disappearance (absorption + catabolism) of tocopherol between feed and lower ileum was 78-90% of the ingested vitamin, and, no significant differences were found with dietary intake or between chickens and turkeys. Of the 3H-labeled material found in the duodenum, 24-40% was not extractable by organic solvents and comprised mainly tocopheryl glucuronides. The duodenal secretion of glucuronides increased with dietary tocopherol intake, and less than 30% of the secreted glucuronides were reabsorbed by the small intestine. The duodenal organic solvent-extractable 3H-contained 30-40% material that appeared to be tocopheryl quinone. This proportion increased with distance from the pylorus. Turkeys excreted 2.5- to 7-fold more glucuronides than chickens. This explains in part the lower plasma and tissue concentrations of tocopherol observed in turkeys.