Actavia 0 Antunović, Z. Bogut, I. Senčić, D. Katić, M. Mijić, P. 2005 2005-8-31 369-375 Biological investigations on ewes of Merinolandschaf breed (n = 10) were conducted by the 60^th lactation day during the summer on pasture. Ewe milk sampling was carried out on the 2^nd; 10^th; 30^th and 60^th lactation day. An electrothermal technique was used to determine Cd and Pb concentrations in food and milk whereas As and Hg concentrations in food and milk were determined by a hydrid technique on an atomic absorption spectrophotometer. The investigation results indicate that concentrations of selected toxic elements in ewe milk varied in dependence on lactation stage. In colostrum (2^nd lactation day) Cd and Pb (0.011 and 0.035 mg/kg)concentrations were significantly higher (P < 0.01) whereas As (0.011 mg/kg) concentrations were lower in comparison with milk on the 10^th (Cd: 0.004; Pb: 0.022; As: 0.025 mg/kg), 30^th (Cd: 0.005; Pb: 0.024; As: 0.028 mg/kg) and 60^th (Cd: 0.006; Pb: 0.026; As: 0.029 mg/kg) lactation day. However, no significant differences (P > 0.05) were found in milk Hg concentration in relation to lactation stage (from 0.021 to 0.026 mg/kg). The selected toxic elements appeared to be present in ewe milk in very low concentrations. 8 50