Bioavailability to chicks of selenium in barley, oats and meat meal

Toxicity of seleno-L-methionine, seleno-DL-methionine, high selenium wheat, and selenized yeast to mallard ducklings

The toxicity of four chemical forms of selenium (seleno-L-methionine, seleno-DL-methionine, selenized yeast, and high selenium wheat) was compared in day-old mallard ducklings (Anas platyrhynchos). In the first experiment, in which the basal diet was 75% wheat, survival after 2 weeks was lower for ducklings fed 30 micrograms/g selenium as seleno-L-methionine (36%) than for ducklings fed 30 micrograms/g selenium as seleno-DL-methionine (100%) or 30 micrograms/g selenium from high selenium yeast (88%). The concentration of selenium at 2 weeks in the livers of survivors was similar for ducklings fed 15 micrograms/g selenium as seleno-DL-methionine (12 micrograms/g, wet weight), seleno-L-methionine (11 micrograms/g), and high selenium wheat (11 micrograms/g), but was lower when the selenium came from selenized yeast (6.2 micrograms/g). When fed 30 micrograms/g selenium from the various sources, the selenium concentrations in liver were 20 micrograms/g for seleno-DL-methionine, 19 micrograms/g for seleno-L-methionine, and 9.9 micrograms/g for selenized yeast. In a second experiment, in which the basal diet was a commercial duck feed, survival after 2 weeks was 100% in ducklings fed 30 micrograms/g selenium as seleno-DL-methionine, seleno-L-methionine, or selenized yeast. Selenium concentrations in liver were similar for ducklings fed the 30-micrograms/g selenium diets as the DL or L forms of selenomethionine (27 and 25 micrograms/g), but lower for ducklings fed selenized yeast (13 micrograms/g).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dietary vitamin E and selenium deficiency on chicken splenocyte proliferation and cell surface marker expression

Beginning at hatching, chicks were fed a Basal diet, without vitamin E or selenium (Se) or the same diet supplemented with vitamin E (100 IU/kg) and Se (0.2 ppm). The effect of these treatments on the expression of cell surface markers (CT-1a, CD3, CD4, CD8, sIgs, and Ia) defining specific thymocyte and peripheral blood leukocyte (PBL) subpopulations were examined using flow cytometric analyses. In parallel studies the effect of the dietary deficiencies on splenocyte proliferative responses to ConA or PHA stimulation was examined. The mean expression of CD3 and CT-1a per cell was increased while CD8 and CD4 expression was decreased on thymocytes from chicks fed the Basal diet. The proportion of double negative (CD4-, CD8-) thymocytes and single positive CD8+ thymocytes was significantly decreased while single positive CD4+ and double positive (CD4+, CD8+) thymocytes were significantly increased by the dietary vitamin E and Se deficiencies. The dietary deficiencies resulted in a decreased proportion of peripheral T cells and specifically decreased the number of CD4+ PBL. The proliferative response to both ConA and PHA was impaired by the vitamin E and Se dietary deficiencies. The proliferative response could be fully reconstituted but only after vitamin E and Se supplementation for periods longer than 1 week. Plasma SeGSHpx and alpha-tocopherol levels paralleled the mitogen responsiveness observed. These results support the conclusion that vitamin E and Se deficiencies may affect both the maturation of specific lymphocyte subpopulations and the functional and proliferative capabilities of the peripheral lymphocytes.

Utilization of dietary sodium selenite, barley, oats and meat meal selenium by the chick

The biological availability of selenium (Se) in barley, oats and meat meal as compared to that in sodium selenite was determined by whole blood glutathione peroxidase (GSH-Px) activity and Se concentration depletion-repletion bioassays. One day old White Leghorn chicks, initially of low-Se status, were further depleted for Se by feeding a low-Se casein basal diet (0.03 mg Se/kg diet) adequate in vitamin E for the first two weeks of life. Repletion treatments of Se at graded levels supplemented by the natural sources or sodium selenite were then provided for 4 weeks. A multiple regression equation was calculated to relate the final whole blood GSH-Px activity and Se concentration to the dietary intake of Se. The percent biological availability of Se present in the natural sources was evaluated by slope ratio analyses in comparison to the standard, sodium selenite (100%). The activity of whole blood GSH-Px established a relative bioavailability for barley, oats and meat meal Se of 85, 41 and 25%, respectively (as mu kat/l), and 81, 51 and 17%, respectively (as mu kat/g Hb). The estimated bioavailability of Se in the different natural sources, as measured by blood Se concentration was: barley, 104%; oats, 99% and meat meal, 69% in comparison to that of sodium selenite. Thus, selenite Se was superior to the natural Se sources for the induction of GSH-Px activity. Barley Se appeared to be of higher biological value to chicks than did oats and meat meal Se. Even though meal Se was retained in appreciable amounts in chick blood, it showed the poorest utilization for the synthesis of blood GSH-Px.