Variation of erythrocyte glutathione peroxidase activity in Finn sheep

Erythrocyte glutathione peroxidase (GSH-Px) which was analysed on a flock of Finn sheep (266 sheep) showed variable activity despite the same diet and selenium intake. Mating experiments suggested that the GSH-Px activity was genetically determined. The low GSH-Px animals showed better performance as shown by a significantly reduced mortality rate of their offspring. Evidence of larger weight gain and wool production in the low GSH-Px sheep was obtained. The GSH-Px activity slightly decreased with age. The erythrocyte GSH-Px activity did not show much correlation with other genetical markers such as the potassium type, GSH type, haemoglobin type or sex. It is proposed that the low GSH-Px may represent an adaptation to low selenium intake.