EN
The study was carried out on three groups of cows kept in the systems: I - indoor and pasture, II - indoor with a run, III - indoor. The experiment lasted one year and involved summer and winter feeding. Contents of vitamin A and E in blood serum were determined. The highest serum levels of vitamin E were determined in animals kept in both indoor + pasture and indoor + run systems. The system of keeping did not affect significantly the concentration of vitamin A in the examined period. Statistically significant differences occured in some months but generally in all the systems, its content was at a similar level.