COMPARISON OF INORGANIC AND ORGANICALLY B OUND SELENIUM-SUPPLEMENTATION IN DAIRY-COWS

From June to September 1996 three groups of 10 cows each (Fleckvieh an d Braunvieh) at the research farm of the University of Veterinary Medi cine were chosen to conduct a feed trial. Group I received a daily sup plement of 5 mg Selenium as selenomethionine (organic selenium), group II the same amount of Selenium as sodium selenite (inorganic selenium ) and group III was used as control group without supplementation. In this period whole blood-, serum- and milk samples were drawn every thr ee weeks (6 times). At the beginning, in the middle and at the end of the trial feed samples were taken. For selenium analysis a direct dete ction method was used. In the supplemented groups all evaluated parame ters increased whereas the selenium contents declined in animals of th e control group. There was no significant difference in Selenium conce ntration in blood at any time between group I and II. Serum concentrat ion in group I was significantly higher at day 42, 84 and 105. Milk co ncentration was significantly higher in group I at any time of the tri al. All animals that were supplemented with 5 mg selenium/day were abl e to meet the requirements for selenium in blood and serum. No direct advantage for the dairy cow was seen for either selenium source. Howev er there was a difference of the selenium content in milk. There were significantly higher selenium levels with the organic supplemented ani mals. Because of that, there is an advantage for the supply as well fo r the calves as for man.