[Selenium deficiency without clinical symptoms in young cattle on a dairy farm].

On a dairy farm a selenium deficiency was diagnosed on the basis of the blood chemistry of heifer calves. Of ten heifers, aged five to fourteen months, six animals had a glutathione peroxidase (GSH-PX) activity lower than 10 U/gHb. A good correlation was found between this low GSH-Px-activity and the selenium concentration in the blood. The animals had no symptoms of selenium deficiency nor elevated CPK levels. On the basis of the vitamin E-concentration in the blood it is postulated that the lack of symptom is mainly caused by the amount of vitamin E in the ration (grass and grass silage).