Possible involvement of selenium in Staphylococcus aureus inhibition in cow's whey
Previous investigations have shown that selenium supplementation inhibits growth of mastitis pathogens in cow's milk. The present study was performed to clarify the role of selenium in defence mechanisms of mammary gland. We have examined the effects of selenium supplementation on Staphylococcus aureus growth inhibiting activity in whey. Six selenium-supplemented and six non-supplemented Estonian dairy cows were used for this study. Selenium-supplemented cows received 4 mg organic selenium in the form of selenium yeast in their daily diet for 8-week period. Cows from non-supplemented group received the same amount of yeast free of selenium in their diet. All cows had initially low blood glutathione peroxidase (GPx) activity (≤1.02 μkat/g Hb). During the 8-week experiment these cows had low somatic cell count (<300 000 cells/ml) and negative bacteriological findings in their quarter milk samples. Bacterial growth inhibitory activity in specific whey fractions was clearly evident in 3 out of 6 cows supplemented with selenium. The inhibitory effect was more profound if the cow's blood GPx activity exceeded 4 μkat/g Hb, whereas in non-supplemented cows the inhibition of S. aureus growth was not observed. This study confirms the presence of selenium-dependent antibacterial activity in cow's milk.
Document Type: Research Article
Affiliations: Department of Clinical Veterinary Sciences, Pharmacology and Toxicology, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland, and
Publication date: April 1, 2006