Direct and indirect assessment of selenium status in cattle - a comparison.

Pavlata L. , A. Pechová, J . I l lek: Direct and Indirect Assessment of Selenium Status in Cattle a Comparison. Acta vet. Brno 2000, 69: 281-287. Selenium concentration and activity of glutathione peroxidase (GSH-Px) as direct and indirect indicators of selenium status were determined in whole blood samples collected from 326 cattle in 30 herds kept in various regions of the Czech Republic. The GSH-Px activity in the samples was measured by the UV method, using the set supplied by Randox. Selenium in the sample was measured using the hydride technique AAS. The two variables showed a close and significant correlation (r = 0.90; p < 0.01). The regression line, defined by the equation y = 6.44x + 21.4, allowed us to determine the GSH-Px activity of 665.4 μkat. l-1 as equivalent to selenium concentration in whole blood 100 μg. l-1. Mean selenium concentration and mean GSH-Px activity found in whole blood samples were 78.25 ± 46.67 μg. l-1 and 525.51 ± 335.56 μkat. l-1, respectively. Insufficient or marginal supply of selenium was diagnosed in 64% of the animals in terms of selenium concentration, in 63% of the animals in terms of GSH-Px activity and in 55% of the animals with selenium concentrations <100 μg. l-1 and GSH-Px activity < 665.4 μkat. l-1. In this study, close dependence of GSH-Px activity and selenium concentration in the blood of cattle was found. Activity values of GSH-Px were determined for the use in diagnosis of insufficient selenium in cattle in the Czech Republic. Glutathione peroxidase, whole blood, AAS, correlation, diagnostics Selenium had been the subject of only toxicological studies in animals and humans until Schwartz and Foltz (1957) pointed out its physiological role. Currently, many biological functions of this element present in various selenoproteins have been described. In eukaryotic organisms, selenocysteine has been identified as a component of glutathione peroxidase, tetraiodothyronine 5’-deiodase, protein P, selenoprotein W, and selenoprotein isolated from murine sperm mitochondriae (Fuchs 1996). Their biological functions in various animal species are the subject of continuing research. Selenium deficiency in various animal species is manifested by both nonspecific and specific clinical signs. Their severity depends on the degree of deficiency and exertion the animal is exposed to. Well-known animal diseases due to selenium deficiency include nutritional myodystrophy of ruminants, hepatic necrosis of rats, pancreatic degeneration, reproductive failures, encephalomalacia of chicks, and others (Shamberger 1983). Since such diseases become clinically apparent only in animals suffering from a serious selenium deficiency, development of exact and practical methods for the diagnosis of subclinical metabolic disorders or insufficient selenium supply is desirable. In addition to clinical signs and microscopic lesions in muscular tissue, low selenium status can be diagnosed by increased ativities of selected enzymes of muscle cells (aspartate aminotransferase, lactate dehydrogenase and, foremost, creatine kinase). More exact methods include direct determination of selenium in blood and tissues and indirect assessment of selenium status by measurement of activity of ACTA VET. BRNO 2000, 69: 281–287 Address for correspondence: MVDr. Leo‰ Pavlata Clinic of Diseases of Ruminants, Faculty of Veterinary Medicine University of Veterinary and Pharmaceutical Sciences Brno Palackého 1-3, 612 42 Brno, Czech Republic Phone: +420 5 4156 2407 Fax: +42 74 88 41 E-mail: pavlatal@vfu.cz http://www.vfu.cz/acta-vet/actavet.htm