Correlation between glutathione peroxidase activity and the quantity of selenium in the whole blood of beef calves

The aim of the study was to establish concentration of selenium and the per tinent activity of glutathione peroxidase (GSH-Px) in whole blood that coul d be used as reference values in future research. The first part of study w as carried out on clinical healthy beef calves (n = 35), fed a basal diet a nd a ready-made fodder mix that contained 0.1 mg.kg(-1) selenium. In the se cond part of our research, we investigated the GSH-Px activity in a group o f calves (n = 47) that had not received supplements added to the basal diet . The research was carried out in the north-west Croatia, in the region kno wn to be poorer in selenium. We determined GSH-Px activity in whole blood b y the "Ransel" method adapted to a Technicon RA-1000 at 37 degrees C. Deter mination of Se concentration was done with a modification of the method giv en by Perkin-Elmer HGGS. The mean value of the Se concentration in the whol e blood of the first group of calves was 200.22 +/- 45.2 mu g.l(-1) and per tinent average GSH-Px activity was 764.6 +/- 197.8 mu kat.l(-1). From the r esults obtained, a correlation between Se and GSH-Px was calculated (r = 0. 82; P < 0.001). The mean values of the GSH-Px activity in herd that did not receive a supplement were 435.3 +/- 155.76 mu kat.l(-1). Out of 47 animals of the second herd, four animals (8.51%) had lower values than those recom mended as sufficient. This study confirmed that after the calculation of th e correlation between Se and GSH-Px, glutathione peroxidase activity determ ination can be used as a rapid and simple proxy for the determination of se lenium concentration in whole blood.