Kuricová S., K. BoldiÏárová, ª. Gre‰áková, M. Levkut, ª. Leng: Chicken Selenium Satus When Fed a Diet Supplemented with Se-Yeast. Acta Vet. Brno 2003, 72: 339-346. This experiment was designed to investigate the effects of the feed supplementation with inorganic and organic forms of Se on the activity of blood glutathione peroxidase (GSH-Px) and the Se levels in blood and tissues in young female chickens of the laying strain Isa Brown. The first group of birds received the basic diet (BD) with Se content 0.12 mg . kg -1 of dry matter (DM). Diets for Groups 1, 2 and 3 consisted of BD supplemented with sodium selenite 0.2 mg·kg -1 of DM, Se-enriched yeast 0.2 and 0.7 mg·kg -1 of DM, respectively. The experiment lasted from hatching until 7 weeks of age. The activity of blood GSH-Px was found to be dose-dependent throughout the experiment with no differences due to the form of Se administered. The selenium analysis in blood and liver samples revealed also the Se dose dependent responses but with significantly higher values recorded in chickens aged 5 weeks and older chickens and supplied with the equivalent amounts of organic Se source. Other tissue Se levels were also highest (P < 0.05) in the group with its largest intake. The values of Se content in the breast muscle were higher (P < 0.001) in chicks of Group 3 during entire experiment and they reached the doubled values than in the birds given selenite (11.54 ± 0.4 vs. 5.47 ± 0.2 µmol·kg -1 of DM, in 7-weekold birds). On the other hand, no differences in this parameter were determined between the chicks fed just BD or BD supplemented with Na 2 SeO 3 . At the end of experiment, the intake of Se-yeast (Group 3) resulted in significantly (P < 0.05) higher Se levels in the heart, in lungs and in the gizzard than BD with selenite. No effects of the form of selenium used could be found in the spleen and kidney samples of 7-week-old chicks. The results demonstrate the evident advantage of supplementation of poultry feed with the selenium-enriched yeast due to more effective Se utilization and formation of mobile body deposits of this microelement than in the case of supplementation with selenite.

The effect of selenium supplementation on the rumen protozoan population of sheep was demonstrated. Both the total and generic counts of rumen ciliates in sheep fed a diet with basal Se content (70 microg/kg dry matter) were compared to those of animals given feed supplemented with inorganic (disodium selenite) or organic Se (selenized yeast) (310 microg/kg dry matter). The genera of Entodinium, Isotricha, Dasytricha, Ophryoscolex, Diploplastron and Polyplastron occurred in all sheep except for the control, in which Ophryoscolex was not observed. The population of Ophryoscolex caudatus f. tricoronatus was significantly higher in sheep supplemented with organic Se than in animals given inorganic Se (by 160 %). Supplementation of feed with selenized yeast induced significant growth in the Diploplastron population (by 63 %) while no change occurred in sheep given selenite. The populations of Dasytricha ruminantium and Polyplastron multivesiculatum were higher than control in both Se-supplemented groups. The ciliate population of Entodinium spp. was not influenced by Se supplements. Our results suggest a protective effect of Se feed supplementation on the development of some rumen ciliate species in young ruminants.

The experiment was designed to investigate the effects of feed supplementation with selenite or selenized yeast on parameters of antioxidant and selenium status of laying hens.Hens of laying breed Shaver Starcross 288 were randomly divided at the day of hatching into 4 groups and fed for 9 months on diets which differed only in amounts or forms of selenium supplemented. Group 1 was fed the basal diet (BD) with native Se content 0.1 mg . kg -1 DM. Groups 2 and 3 were fed the BD diets supplemented with equivalent Se dose 0.4 mg . kg -1 DM of either sodium selenite or Se-yeast, respectively. The diet for group 4 was supplemented with Se-yeast at Se dose 0.9 mg . kg -1 DM. The activities of glutathione peroxidase (GPx) in blood and tissues of liver, kidney and duodenal mucosa were significantly increased by Se supplementation, but no differences due to form or dose of Se were observed. Both Se sources resulted in significant reduction of superoxide dismutase (SOD) activity in erythrocytes. Malondialdehyde (MDA) content in kidney tissue was reduced by both Se sources, but its production in liver tissue was inhibited by Se-yeast only. Selenium supplementation did not influence the levels of MDA and -SH groups in plasma. Altrough both Se significantly raised Se concentrations in blood and tissues of liver, kidney, spleen, hearth and duodenal mucosa, significant Se deposition into muscles appeared in hens given Se-yeast only. The presented results suggest that Se-yeast is more effective in maintenance of antioxidant and selenium status of laying hens than selenite.

The effects of feed supplementation with inorganic and organic forms of selenium (Se) on the activities of blood glutathione peroxidase (GPx), superoxide dismutase (SOD) in erythrocytes as well as on total antioxidant status in plasma (TAS) were examined in lambs. Fifteen animals were divided into three groups and fed experimental diets for 3 months. The first group received the basic diet (BD) providing a daily intake 50.6 μg of Se only. Diets for the second and third groups consisted of BD supplemented with selenium 0.3 mg . kg -1 of DM in the form of sodium selenite or Se-enriched yeast and giving a total daily intake 278.6 μg of Se per animal. Increases in Se concentrations in whole blood, plasma and red blood cells as well as in the activities of blood GPx were highly significant in both supplemented groups, but no differences could be found that were due to the form of Se administered. The activity of SOD in erythrocytes was found to be significantly higher in the selenite group of lambs compared with both groups given BD or Se-yeast. The total antioxidant status was significantly lower in the group given Se-yeast compared with animals on BD, which might be explained by larger amounts of selenide continuously produced from body Se deposits. The presented results support the opinion on the pro-oxidative features of sodium selenite when it is utilized as an animal feedstuff additive.