EN
The examinations were done on 6 stalions, Polish ponnies, at a mean age of 7 years, 360—420 kg of b.w. in two mating seasons. The animals fed a natural diet (2 kg of oat and 5 kg of hay) of a mean content of Zn in the first season 21.84 mg/kg and 17.53 mg/kg in the second season. The number of red and white blood cells, content of haemoglobin, haematocrit, content of a total protein, activity of serum alkaline phosphatase, concentration of Zn, Cu and Ca in serum and in hairs (from thorax) was examined. It was found that the Zn deficient diet caused a deficit of this element in horses manifesting by a decrease of the Zn content in hairs, decrease o