*3.3. Antioxidant Status*

Activity of both antioxidant enzymes SOD and GPx decreased in the erythrocytes of lambs on the diet supplemented with ZnProt compared to ZnSO4 treatment only (both *p* < 0.05). Other parameters of plasma antioxidant status (ALB, TAS, TSH, and MDA) were not affected by dietary treatment (Table 3).

The highest activity of total SOD as well as of Cu/Zn SOD was observed in liver tissue of lambs fed the ZnGly-enriched diet compared to all other lambs (*p* < 0.0001, Table 6). SOD activity in other tissues was not affected by the dietary treatment. Regardless of the source, Zn supplementation increased total antioxidant status (TAS) in the pancreas of all treated lambs (*p* < 0.0001). Other antioxidant parameters, such as GPx activity or concentrations of MDA, TSH, and NPSH in liver, kidney and pancreas tissues, were not affected by Zn feed supplementation.


**Table 6.** Antioxidant parameters in tissues of lambs fed diets (80 mg Zn/kg) differing in Zn source 1.

1 C: basal diet, ZnSO4: zinc sulphate, ZnGly: zinc chelate of glycine hydrate, and ZnPro: zinc chelate of protein hydrolysate. 2 Values (*n* = 6/treatment) are presented as the least squares means. Means within lines with different superscript letters are significantly different (*p* < 0.05).
