The aim of this research was to determine how hematological parameters develop in the course of various levels of copper deficiency in cattle. Animals suffering from copper deficiency were compared to cows undergoing routine health checkups on farms, in which no deficiency of this microelement was found. The study was carried out on three farms in the central Lublin region, and included 80 HF breed dairy cows, aged from 3 to 6 years, at the peak of lactation. The animals were divided into a total of 4 groups - 3 groups at different levels of copper deficiency and 1 group of healthy animals. For the groups of animals studied, a decrease in the parameters of the red blood cell system was found in all the three groups as compared with the control group. The number of erythrocytes in all of the groups was within reference limits; however, the erythrocyte counts were statistically significantly lower (p

24.2.2019