| Summary: | <p>Selenium and vitamin E ranks among very important antioxidant agents protecting the organism from the effect of reactive oxygen forms. The deficiency of both nutrients during pregnancy in cows often result in metabolic disorders and increased of cases of related diseases (mastitis, retained placenta and other reproductive disorders). The aim of the present work was to study the influence of different dose of parenteral administration selenium and vitamin E in dairy cows prior to parturition on selected metabolic parameters, udder health and milk quality. A total in herd of 270 Holstein cattle in east of Slovakia in a two-four lactation-gestation cycle the control group (C) and 2 experimental groups (D, D1) were selected. All groups were similarly housed, managed and fed with the diet containing from 36 to 42 mg vitamin E and 0.2 mg.kg<sup>-1</sup> Se of DM through the study period. In group D a products containing vitamin E and selenium were administered IM four weeks prior to the expected date of parturition in total dose of 1000 mg of dl-α-tocopherol acetate and of 44 mg sodium selenite per cow, respectively. In group D1 the same products were administered twice, four and two weeks prior to parturition. Blood samples were 4 weeks prior to predicted calving date (the time of treatment), on parturition day and at 14<sup>th</sup> day after calving for assessment of plasma vitamin E and selenium concentrations. Blood samples of the calves were drawn from <em>jugular vein</em> at birth and first colostrum was also collected. The occurrence of the mastitis and retained placenta during the first 14<sup>th</sup> day after calving were evaluated in all groups. Higher plasmatic and colostral concentrations of selenium and vitamin E were found only in group with repeat application of Se and vitamin E (D1) collected on the day of parturition. At the 14<sup>t</sup><sup>h</sup> day of postpartal period a trend of lower occurrence of mastitis was observed in group D1 compared to D group, administered IM once and control group. Parenteral supplementation of selenium and vitamin E during pregnancy had no impact on their transmission into the milk and on the presence of bacterial agents in raw milk obtained from dairy cows diagnosed with mastitis.</p><p> </p> <!--[endif] -->
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