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.

Milk somatic cells, factors influencing their release, future prospects, and practical utility in dairy animals: An overview

“…The supplementation of dairy cows having high SCC with antioxidant vitamins such as Vitamin A, C, and E and β-carotene as well as antioxidant minerals such as selenium, zinc, and copper is very effective in reducing their SCC, normalizing their milk composition, and ensuring an early recovery from mastitis [ 80 , 85 , 112 , 113 ]. Supplementation of inorganic selenium reduced IMI in S. aureus -infected dairy cows as compared to non-supplemented animals [ 114 ]. Even the supplementation of a low diet with of Se (0.2 parts per million) reduces SCC in lactating dairy cows [ 115 ].…”

Fine-tuned characterization of Staphylococcus aureus Newbould 305, a strain associated with mild and chronic mastitis in bovines

“…N305, a strain isolated in 1958 from a clinical case of cow mastitis in Orangeville, Ontario, Canada [15] has been used as a model strain of S. aureus mastitis isolates during numerous studies relative to vaccine development [16,17], antibiotic treatments [18], in vitro characterization [19] or in vivo experiments on bovine [20] and mouse models [21]. In particular, N305 was shown to reproducibly induce mild and chronic mastitis in the context of experimental infections [22,23].…”

Fine-tuned characterization of Staphylococcus aureus Newbould 305, a strain associated with mild and chronic mastitis in bovines

“…N305, a strain isolated in 1958 from a clinical case of cow mastitis in Orangeville, Ontario, Canada [ 15 ] has been used as a model strain of S. aureus mastitis isolates during numerous studies relative to vaccine development [ 16 , 17 ], antibiotic treatments [ 18 ], in vitro characterization [ 19 ] or in vivo experiments on bovine [ 20 ] and mouse models [ 21 ]. In particular, N305 was shown to reproducibly induce mild and chronic mastitis in the context of experimental infections [ 22 , 23 ].…”