Relation between selenium content and glutathione-peroxidase activity in blood of cattle.

To identify a simple method for assessing the selenium demand in cattle, the relationship between selenium content in whole blood and the concentration of the selenium containing enzyme glutathione peroxidase (EC 1.11.1.9; GSH-Px) in red blood cells was studied. On six farms with suspected low soil selenium content, blood samples were collected from groups of calves, yearlings and adults at the end of the housing period and of the grazing period. The data obtained showed a highly significant correlation between the parameters mentioned: GSH-Px (U/g Hb) = 3.261 * Se (micrograms/kg) - 40.553. In growing animals there was a decline in Se supply with age, followed by a gradual recovery in heifers. This was most pronounced on some sandy soils and on peat soil. Seasonal effects could not be demonstrated.