Three feeding system were investigated to determine if any of them is more suitable to ensure a better antioxidant protection to meat from Triceps brachii muscle of Aberdeen Angus steers. They were finished on pasture, pasture + concentrate with corn grain, or concentrate alone. TBARS, protein carbonyls and antioxidant enzymes activities have been determined in fresh and aged meat (14 days in vacuum, 1-2°C). The level of TBARS ranged between 0.59-0.64 mg MDA/kg meat, whereas levels of protein carbonyl ranged between 0.18-0.22 mmoles DNPH/mg protein. The activities of catalase and superoxide dismutase are higher in fresh meat of animals fed pasture, compared to those finished on pasture and concentrate, or on concentrate alone. Glutathione peroxidase (GPx) showed higher activities in meat of animals finished on concentrate in comparison those finished on pasture and concentrate, or pasture. However, the results of the investigation do not allow the advising, for now, for the most suitable feeding system for finishing steers that help producers to preserve meat from lipids and protein oxidation. More investigations are necessary to highlight the feeding conditions, which could influence the activities of antioxidant enzyme catalase, SOD and GPx in meat.