Physiological Threshold of Somatic Cell Count in Milk of Polish Heath Sheep and Polish Lowland Sheep

The study was conducted on 320 sheep of two breeds: Polish Heath Sheep (PHS) and Polish Lowland Sheep (PLS). Udder health status was assessed based on somatic cell count (SCC) and bacteriological examination of milk. Cells of the immune system (leukocyte populations and lymphocyte subpopulations) were identified in the blood and milk of sheep by flow cytometry, using a panel of specific monoclonal antibodies and fluorescent dyes. The study showed that the highest proportion of neutrophils and a lower percentage of lymphocytes (CD4⁺, CD8⁺, CD19⁺, WC1-N2⁺) in milk and blood occurred in sheep of both breeds in which milk SCC ranged between 201 and 300×10³ cells/ml. In light of existing research, these results suggest that fluctuations in somatic cell count of ewe milk are physiologically determined up to 200×103cells/ml and result from udder health disturbances above this level.