EN
The aim of this study was to analyse the concentrations of selected elements, such as copper (Cu), manganese (Mn), calcium (Ca), magnesium (Mg), iron (Fe) and zinc (Zn), in the hair of cattle from farms in areas with varying degrees of environmental contamination. The studies were performed on 116 Holstein-Friesian heifers, two years old and weighing around 550 kg. Animals originated from three breeding centers: Kombinat Rolny Sp. z o.o. - Kietrz (Opolskie Province), Hodowla Zarodowa Zwierząt Sp. z o.o. - Knyszyn (Podlaskie Province) and Ośrodek Hodowli Zarodowej Sp. z o.o. - Osięciny (Kujawsko-Pomorskie Province). Hair samples were collected in two periods: during summer (including the period from July 5 to September 6, 2005) and during winter-spring (including the period from January 4 to March 9, 2006), from the flank, just behind the costal arch. The freeze-dried samples were mineralized in an Ethos Plus microwave mineralizator, (Milestone).The tissue was weighed for mineralization, and then 6.25 cm³ of HNO₃ and H₂ O₂, mixed at a 4:1 ratio by volume, was added to 0.2 g of the tissue. Metal concentrations were determined with an atomic absorption spectrophotometer, Solar 969 (Unicam). The analysis indicated that the average content of microelements and macroelements in the hair collected from the three farms was different. Significant differences in the content of certain elements in the hair of dairy cows, kept under the same husbandry and feeding conditions may have been caused by various factors, as well as the characteristics of individual animals.