Evaluating the impact of season and breeding area on blood parameters in Pramenka sheep exposed to thermal stress conditions

This study aimed to investigate seasonal variations in blood parameters of two Pramenka sheep strains, Dubska and Hercegovacka, across and within four areas in Bosnia and Herzegovina, under thermal stress conditions. It included 48 sheep from Vlasic and Kupres (breeding areas of the Dubska strain), and Nevesinje and Podvelezje (breeding areas of the Hercegovacka strain). The investigation was conducted across both summer and winter seasons, encompassing a total of eight herds (two per area). Hematological parameters included erythrocyte, leukocyte, and platelet counts, mean platelet volume (MPV), the total count of granulocytic and agranulocytic leukocytes, hemoglobin concentration (Hb), red blood cell distribution width (RDW) and erythrocyte parameters (MCV, MCH and MCHC). Biochemical analyses covered total bilirubin (TB), total cholesterol (TC), glucose (GLU), urea (UREA), creatinine (CRE), creatine kinase (CK), non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHB), proteins, liver enzymes and electrolytes. Results revealed significantly higher values of red blood cell parameters (Hb, MCH, MCHC) during the summer period in the area of Nevesinje (P<0.05) compared to the Podvelezje area. Additionally, it’s important to emphasize significantly increased levels of basophils during the summer season across all areas, except for Vlasic, when compared to the winter season (P<0.05). Furthermore, the amounts of total proteins, albumin and globulin were significantly increased (P<0.05) in all areas during the summer compared to winter. The study findings underscore the substantial influence of the breeding area, encompassing its geological composition, spatial distribution, and land cover, on specific blood parameters investigated by sheep during periods characterized by adverse temperature conditions.