Hematological and blood biochemical variations in Pramenka sheep under thermal stress conditions

Climate change is one of the greatest global concerns regarding livestock production. The indigenous Pramenka sheep is well known for its ability to survive in difficult environmental conditions, although there is insufficient scientific evidence. This study aimed to evaluate the seasonal variations in some hematological and blood biochemical parameters in two strains of Pramenka sheep – Hercegovačka and Dubska, under natural thermal stress conditions. The calculated Temperature-Humidity Index (THI) data indicated mild to severe heat stress in the localities where the Hercegovačka Pramenka strain was being held, while cold stress was found in all the examined localities. Numerous statistically significant differences in hematological parameters were found between seasons, and within and between the two Pramenka strains. The Dubska strain exhibited significantly higher levels of red blood cells (RBC) and packed cell volume (PCV) compared to Hercegovačka, whereas the Hercegovačka strain displayed significantly higher white blood cells (WBC) and platelet (PLT) levels in comparison to Dubska. Similar patterns were noticed in the blood biochemical parameters - the Dubska strain had more seasonal variations compared to the Hercegovačka Pramenka. During the winter, the Hercegovačka strain demonstrated significantly higher levels of total protein (TP), albumin (ALB), urea (UREA), and creatine kinase (CK) compared to Dubska. Conversely, during the summer, the Hercegovačka strain exhibited significantly higher globulin (GLO) levels, whereas the Dubska strain showed higher levels of ALB and chlorine (Cl). On the basis of our results, both Pramenka strains showed a high adaptive capacity to harsh environmental conditions, the Hercegovačka Pramenka being more adapted to heat stress, and Dubska to cold stress conditions.