Finishing steers with diets based on corn, high-tannin sorghum or a mix of both: Color and lipid oxidation in beef

We tested the hypothesis that feeding high-tannin sorghum (HTS) to steers would produce beef more resistant to oxidative deterioration. We observed lower thiobarbituric acid-reactive substances (TBARS) in Gluteus medius of steers fed HTS before it was displayed (P = 0.028), which could be explained by a reduced response to stress in these animals. While steers finished with corn and corn + HTS had elevated plasma cortisol at the end of the feeding period (P = 0.047 and 0.093, respectively), animals fed HTS and corn + vitamin E did not. However, feeding HTS increased the rate of discoloration and TBARS accumulation after aerobic display of Longissimus lumborum and Gluteus medius. Diet did not affect the activity of oxidation-related enzymes and fatty acid composition of muscle. The accelerated rate of lipid oxidation during display of beef could be partially explained by a numerically lower concentration of tocopherols in the tissue.