Nutritional condition affects the hepatic antioxidant systems in steers.

The objectives of this study were to evaluate the activity of antioxidant systems in the hepatic tissues of steers experimentally subjected to a restricted diet. Hence, the activities of superoxide dismutase (SOD) and reduced glutathione (GSH) and lipid peroxide levels were measured. Nine male Holstein steers were used. They were separated in two groups: three steers in group 1 (control) and six steers in group 2, which were subjected to a restricted diet that covered only 60% of the maintenance requirements. After 30 days, the animals in both groups were killed and studies were completed. Both the CuZn-SOD and the glucose-6-phosphate dehydrogenase activities were significantly decreased (p < 0.05) in group 2, reaching 68% and 60%, respectively, of the concentrations found in group 1. The concentration of GSH in group 2 was 6.71+/-0.9 nmol/mg protein, which was significantly lower (p < 0.01) than that of the controls, 25.7+/-2.4 nmol/mg protein. In addition, the lipid peroxide levels were significantly increased (p < 0.01) in group 2, being 50-60% higher than that in group 1. These results showed that the poor nutritional status caused modifications to the enzymatic antioxidant systems, with a lower ability to reduce oxidative compounds and a state of lipid peroxidation.