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 and colostrum quality. A total of 19 dairy cows from a farm with selenium deficiency were included in the study. The cows were divided in 3 groups (C, E1, and E2). In group E1 a product containing selenium and vitamin E (Selevit inj. a.u.v.) was administered IM four weeks prior to the expected date of parturition. In group E2 the same product was administered twice, eight and four weeks prior to parturition. Group C consisted of control animals to which no product was administered. On the day of parturition samples of blood and first colostrum were collected for laboratory examination. Concentrations of selenium were determined in blood andthat ofvitamin E, thyroid hormones (T3 and T4) and activities of enzymes detecting muscular damage (CK, AST, LD) were determined in serum. Colostrum was analysed to determine the concentrations of selenium, vitamin E, immunoglobulins, as well as to determine its density. The occurrence of the disease during the first month after parturition was evaluated in all groups. Higher concentrations of selenium and vitamin E were found in the samples (experimental groups E1 and E2) collected on the day of parturition. Group E2 showed a significantly (p < 0.05) higher T3 concentration compared to groups C and E1 (3.05 ± 0.42 nmol/l vs 1.88 ± 0.71 and 1.81 ± 0.30 nmol/l, respectively). The same pattern was confirmed for immunoglobulins concentrations in colostrum (34.08 ± 5.93 U ZST vs 22.87 ± 5.41 and 21.38 ± 8.33 U ZST, respectively). Compared to group C, cows in group E2 also showed significantly (p < 0.05) higher concentrations of selenium in colostrum (45.43 ± 10.56 vs 29.29 ± 8.42 µg/l). The administration of selenium and vitamin E did not influence other parameters evaluated in the study. During the first 30 days of the postpartum period a trend of lower occurrence of mastitis was observed in group E2 compared to both group C and E1 (no case of mastitis compared to 5 and 4 cases of treated mastitis, respectively).
Inhibition of hepatic deiodination of thyroxine is caused by selenium deficiency in rats
