title: Somatic cell count in milk of selenium-supplemented dairy cows after an intramammary challenge with Staphylococcus aureus.
abstract: The objective of this study was to evaluate the effect of selenium (Se) supplementation on milk somatic cell count (SCC) in dairy cows. Twelve multiparous Holstein-Friesian cows were fed a diet containing a suboptimal Se concentration (<0.05 ppm, dry basis) starting 2 months before calving. Supplemented cows (n=6) received a single s.c. injection of barium selenate (1 ml/50 kg BW) 45 days prior to calving, whereas control group was kept unsupplemented. Twenty weeks after calving, two mammary quarters (right side) of each cow were challenged with 205,000 cfu/ml of Staphylococcus aureus (strain Newbould 305). Blood was collected bi-weekly until day 150 of lactation for the analysis of blood glutathione peroxidase (GPx1; EC 1.11.1.9) activity. To re-isolate the challenging pathogen and to evaluate SCC, aseptic milk samples were collected daily starting on the day of challenge, and finishing 7 days after inoculation. Unsupplemented cows had a lower activity of GPx1 through the experiment (P<0.001). Natural log SCC (lnSCC) was higher in unsupplemented than Se-supplemented cows (P=0.04), showing evidence of significance after 5 days. Selenium supplementation of dairy cows fed a diet containing a suboptimal Se concentration, resulted in higher blood activity of GPx1, and lower mean lnSCC after an intramammary challenge with Staph. aureus.
authors.affiliation: Department of Health Management, University of Prince Edward Island, Charlottetown, PE, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Kruze
authors.forename: A
authors.initials: A
authors.lastname: Ceballos
authors.forename: H
authors.initials: H
authors.lastname: Stryhn
authors.forename: A
authors.initials: A
authors.lastname: Mella
authors.forename: R
authors.initials: R
authors.lastname: Matamoros
authors.forename: P A
authors.initials: PA
authors.lastname: Contreras
authors.forename: V
authors.initials: V
authors.lastname: Leyan
authors.forename: F
authors.initials: F
authors.lastname: Wittwer
mesh_terms: D000818:Animals; D002417:Cattle; D002452:Cell Count / Q000662:veterinary; D019587:Dietary Supplements; D005260:Female; D005979:Glutathione Peroxidase / Q000378:metabolism; D007113:Immunity, Innate; D008414:Mastitis, Bovine / Q000097:blood* / Q000276:immunology; D008892:Milk / Q000166:cytology*; D011247:Pregnancy; D012643:Selenium / Q000008:administration & dosage / Q000097:blood / Q000172:deficiency; D013203:Staphylococcal Infections / Q000097:blood / Q000276:immunology / Q000662:veterinary*; D013211:Staphylococcus aureus / Q000472:pathogenicity; D013997:Time Factors
chemical_list: D005979:Glutathione Peroxidase; D012643:Selenium