SELENIUM DEFICIENCY WITHOUT CLINICAL SYMP TOMS IN HEIFER CALVES ON A DAIRY FARM

On a dairy farm a selenium deficiency was diagnosed on the basis of th e blood chemistry of heifer calves. Of ten heifers, aged live to four theen months, six animals had a glutathionen peroxidase (GSX-PX) activ ity; lower than 10 U/gHb. A good correlation was found between this lo w GSH-Px-activity and the selenium concentration in the blood. The ani mals had no symptoms of selenium deficiency nor elevated CPK levels. O n the basis of the vitamin E-concentration in the blood it is postulat ed that the lack of symptoms is mainly caused by the amount of vitamin E in the ration (grass and grass silage).