This study has been done to determine the effect of species and sexes on antioxidan enzymes and lipid peroxidation of liver tissue in ruminants. In the present study, the activities of glutathione peroxidase (GSH-Px) and Catalase (CAT) that play roles in the free radical metabolism in liver tissue and malondialdehyde (MDA) concantration in ruminants, evaluated as healthy determined after clinical and postmortem inspection, bred in Elazığ province were measured. Liver tissue was made homogenize for GSH-Px activity in 50 mM Tris, 0,1 mM EDTA buffer, and for CAT activity and MDA concentration in 1,15 % KCl. GSH-Px and CAT activities were measured by the method of Beutler and, MDA levels by method of Ohkawa et al.

Comparison of intra and inter species showed that species and sexes have effects on these parameters in different degrees.Cattle had greatest liver GSH-Px (44.51 ± 1.14 U/g protein) activity, whereas sheep had the greatest liver CAT (59.53±1.03 U/mg protein) activity. Goats also had the greatest MDA (54.65 ± 2.12 nmol MDA/g wet tissue) liver concentration. In comparison of male and female, Liver GSH-Px (48,57 ± 1,57 nmol MDA/g wet tissue) activity of female cattle; liver MDA (53.74 ± 1.04 nmol MDA/g wet tissue) concentration of rams; liver GSH-Px (36.90 ± 1.25 U/g protein) and CAT (66.08 ± 0,99 U/mg protein) activities of female sheep were greater than other sex. Female goats had significantly greater liver GSH-Px (54.91± 1.69 U/g protein) and CAT (53.31±1.36 U/mg protein) activities, and nonsignificantly high MDA concentration compared with male goats.

Results ot this study suggested that antioxidant levels between species and sexes may depend on differentiation in oxidant damage mechanism of cattle, sheep and goats or presence of other endogenous antioxidants in these animals.