Comparison of effect of parenteral and oral supplementation of Selenium and vitamin E on selected antioxidant parameters and udder health of dairy cows.

The aim of this study was to compare the effect of parenteral and oral supplementation of Selenium (Se) and vitamin E (VTE) on selected antioxidant parameters in blood and colostrum as well as their effect on the incidence of mastitis in dairy cows during the final phase of gravidity (6 weeks) and first two weeks after calving. For the practical part of the study 36 dairy cows of Slovak pied breed in the second to fourth lactation-gestation cycle were selected. The animals weredivided into three groups: the control (C) and two experimental groups (D1 and D2). The selected groups were treated as follows: in group D1 products containing Se (Selevit inj.) and vitamin E (Erevit sol. inj.) were administered intramuscularly twice, six and three weeks prior to parturition; in group D2 a vitamin-minerals supplement in the form of sodium selenite (Na2SeO3) and dl-α-tocopherol acetate were supplemented orally for six weeks calving. The blood samples were collected from the vena jugularis in dairy cows approximately 42 days before calving (control sampling), on parturition day, and the 14th day after calving. Higher concentrations of Se and VTE were found in the blood plasma samples of both experimental groups collected on the day of parturition. In addition, the orally supplemented group (D2) showed higher Se and α-tocopherol concentrations in blood plasma on the14th day after calving as well a reduction of occurrence of mastitis by about 25 % compared to the control group. The relationship between inflammatory response and oxidative stress was also confirmed. The concentrations of milk malondialdehyde indicating lipid peroxidation during mastitis were significantly higher in milk samples from infected cows than in milk samples from healthy animals in each monitored group. In order to prevent oxidative stress and moderate inflammatory response in dairy cows it is very important to optimally balance their nutritive needs with an appropriate ratio of Se and VTE supplements. Therefore we still recommend supplementation of the cows' postpartum dietwith 0.5 mg of Se/kg dry matter (DM) and 102 mg of dl-α-tocopherol acetate/kg DM to stabilize their optimal blood levels, stimulate the activity of glutathione peroxidase and reduce the incidence of mastitis.