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.

Abstract This study aimed to investigate the effects of dietary supplementation with modified-hen-egg-yolk on plasma lipids and lipoprotein profiles in rats. During the four-week-experiment, 64 Wistar rats were divided into four groups of 16 (eight of both sexes), and fed commercial rat food (group C); food containing 70% commercial rat mixture and 30% freshly cooked egg yolk originating from laying hen eggs fed with 3% fish oil (group F); 3% palm olein (group P), or 3% lard (group L). The cooked egg yolk in the rat diet affected the concentrations of plasma total and LDL-cholesterol in males of the P and L groups. Cholesterol and total fat in the diet did not have a hypercholesterolemic effect on their own, but when in combination with fatty acid composition, they could contribute to an increase in plasma total and LDL cholesterol concentrations in rats. HDL-cholesterol was the most resilient plasma lipoprotein of rats to dietary treatments in our experiment. Compared to the control group, the addition of hen egg yolk to the rat diet regardless of its quality, adversely affected the values of HDL-C/TC and HDL-C/LDL-C in both males and females.