Intestinal absorption of 75Se-labeled sodium selenite and selenomethionine in chicks: effects of time, segment, selenium concentration and method of measurement.

The purpose of the present experiments was to obtain information on the intestinal transport of different selenium compounds in chicks. Absorption of selenium was studied in 3-wk-old white Leghorn cockerels both by introducing the radiolabeled selenium compounds into ligated intestinal loops of the anesthetized birds and after oral or parenteral administration of the isotope to previously fasted animals. Increasing the stable selenite concentration slightly reduced the percentage of [75Se]selenite transferred from the intestinal lumen to the body, while the transport of [75Se]selenomethionine was not similarly affected by the carrier concentration. Selenomethionine was more rapidly removed from the ligated intestinal segment and more efficiently retained after oral or parenteral administration. It was shown that the liver selenium cannot be used as an indicator of the efficiency of selenium absorption in short-term studies, since after dosing the liver accumulates sodium selenite more efficiently than selenomethionine, in spite of the greater percentage absorption of the latter compound. The percentage absorption of both selenium compounds was greatest from the duodenal segment of the small intestine. The transport of these selenium compounds does not appear to depend on the dietary level of selenium since the percentage absorption was not altered by feeding the birds diets supplemented with 0.4 or 4.0 ppm selenium prior to the measurement of absorption. The data imply that there are differences, in the chick, in the processes by which various selenium compounds are transported across the intestinal epithelium and retained in the body. The differences in absorption are not of nutritional importance, since, regardless of the chemical form, selenium is efficiently absorbed.