*2.6. Antioxidant Assays*

Thiobarbituric acid reactive substances (TBARs) were measured colorimetrically according to Tappel and Zalkin [45]. The catalase activity (U/mL serum; EC 1.11.1.6, CAT) was measured according to Luck [46]. The superoxide dismutase activity (U/mL serum; EC 1.15.1.1, SOD) was evaluated according to Misra and Fridovich [47]. The total antioxidant

capacity (TAC) was estimated colorimetrically using commercial kits produced by Bio Diagnostic, Egypt according to the method of [48].

#### *2.7. Antibody Titers against SRBCs*

The primary and secondary immune response was assayed by measuring antibody titer against sheep red blood cell counts (SRBCs), as the agglutination titer described by Wegmann and Smithies [49]. The agglutination titer was calculated as the log of the reciprocal of the highest serum dilution for the whole agglutination [50].
