The concentration of macro and trace elements, fatty acids (FAs), vitamins, total cholesterol (TCh) in blood as well as in other tissues can be modulated by diet composition. Thus, the purpose of the present study was to evaluate the effects of fish oil (FO), carnosic acid (CA) and selenized-yeast (SeY) or selenate (SeVI) on concentration of FAs, TCh, α-tocopherol (αT) and selected elements in whole blood of lambs. Thirty male lambs were allocated into 5 groups of 6 animals each and fed for 35 days the following diets: control – basal diet (BD) with 3% rapeseed oil (RO), ROFO – BD with 2% RO and 1% FO, CA – BD with 2% RO, 1% FO and 0.1% CA, CASeY – BD with 2% RO, 1% FO, 0.1% CA and 0.35 mg Se as selenized-yeast (SeY) per kg of BD and CASeVI – BD with 2% RO, 1% FO, 0.1% CA and 0.35 mg Se as sodium selenate (SeVI) per kg of BD. In animals fed CASeVI diet the levels of saturated (SFAs), mono- and polyunsaturated FAs, thrombogenic-SFAs and atherogenic- SFAs decreased in comparison to the control group. On the other hand, in lambs fed CASeY diet the concentration of TCh in blood increased in comparison to lambs fed CA and CASeVI diets. Moreover, feeding CASeY diet also enhanced the concentration of αT in blood as compared to the animals fed ROFO and CASeVI diets. The lowest αT concentration in blood was noted in blood of lambs fed CASeVI diet. Feeding diets supplemented with SeY or SeVI increased the concentrations of Se and malondialdehyde in blood in comparison to other diets. So, the whole blood can be treated as the valuable non-invasive marker for evaluation of ruminant health status and nutritional quality of ruminant feeds.