The objective of this study was to investigate the effect of maintenance system as well as the effect of Se, Zn, and vitamin E supplementation of ram-lambs on the slaughter value and concentration of mineral elements in the loin muscle of lambs. The experiment was conducted on 72 Polish Merino ram-lambs divided into three groups: group C, indoor with no supplement, 19 lambs; S, indoor with supplement, 23 lambs; G, outdoor with no supplement, 30 lambs. From birth all the lambs were maintained indoor with their dams and then weaned at the age of 8 weeks. The rams from group C and S were placed in individual straw-bedded pens and fattened individually with concentrate mixture offered ad libitum until the age of 16 weeks. The lambs from group G were grazed every day from May to July (2 months). During the fattening period each lamb from the supplemented group S was administered per os 1 mL 0.1% $Na_2SeO_4$ (Se, 0.42 mg), 3 mL 10% $ZnSO_4$ (Zn, 68 mg), and 1 mL premix protect vitamin E (0.1 g ${alpha}$-tocopherol, 5 mg lysine, 5 mg methionine) daily. A comparison of half carcasses across the groups has shown no difference between the control group and the one with supplements, while the weight of half carcasses in the grazing group was smaller in comparison with groups C and S (p<0.001). The meat content in the pelvic limb showed no differences across all groups under study. The pelvic limb of grazing lambs contained less fat compared to the control and supplemented groups (p<0.001). The concentrations of Se and Zn in the blood plasma of ram-lambs from the supplemented group were significantly higher than for the control and grazing lambs. Inorganic Se and Zn supplementation with vitamin E to the diet of lambs increased Se and Zn levels in loin muscle (p<0.001) to $0.46{mu}g/g$ and $32.9{mu}g/g$ in fresh tissue, respectively.