An examination was made of the relationship in Romney sheep between
selenium deficiency and (i) the state of the liver
drug metabolising
enzyme system, (ii) subclinical liver damage, (iii) susceptibility to facial
eczema, and (iv) susceptibility to ryegrasss staggers. The microsomal electron transport detoxifying
enzymes based on
cytochrome P-450 were unaffected by Se deficiency, suggesting that these
enzymes are uninduced on ryegrass/clover pastures.
Selenium deficiency had no effect on
sporidesmin-induced liver damage, which makes it unlikely that peroxidative events countered by Se-dependent
glutathione peroxidase (E.C.1.11.10) have a major role in the mechanism of
sporidesmin toxicity.
Selenium deficiency did appear to suppress the development of photosensitisation. There was no major effect on ryegrass staggers and no deficiency-induced subclinical liver damage.