Steers supplemented Diamond V NaturSafe, a yeast fermentation product, at the manufacturer’s current recommended dose for receiving cattle (12 g/steer/d) during a 19-d preconditioning period exhibited greater antioxidant (glutathione) capacity prior to a 19-h transit event. Regardless of treatment, activity of the antioxidant enzyme Mn-superoxide dismutase was increased post-transit, suggesting more antioxidants may be needed to combat transit-induced stress. Supplementing NaturSafe at 12 g/steer/d during both preconditioning and receiving also improved feedlot performance early in the receiving period (d 0 to 30). These data suggest increasing antioxidant status may be an effective strategy to help cattle prepare for and recover from a stressful event, such as long-distance transit.