Effects of vitamin E supplementation are most easily recognized for those variables that respond to antioxidants. When ground beef has been packaged in a high-oxygen atmosphere, which is known to accelerate lipid oxidation, vitamin E supplementation has resulted in beef with an extended period of redness. In contrast, vitamin E supplementation appears to not influence meat tenderness, microbial growth on fresh beef products, or cooked color of ground beef. There is some evidence for improved cattle health when dietary vitamin E supplementation is initiated upon receipt of feeder cattle into feedyards. Secrist et al. summarized 21 studies and concluded that average daily gain was increased and feed conversion efficiency tended to improve with vitamin E supplementation.