Feeding vitamin E may reverse sarcoplasmic reticulum membrane instability caused by feeding wet distillers grains plus solubles to cattle

Research has shown feeding wet distillers grains plus solubles (WDGS) in beef feedlot diets increases PUFA concentration in the sarcoplasmic reticulum (SR) membrane, thereby altering membrane integrity, resulting in more rapid postmortem calcium leakage and improving tenderness through early activation of calcium-dependent proteases. Supplementation with antioxidants may mitigate such effects. A total of 160 steers were finished on a corn-based diet with 0 or 30% WDGS and 4 antioxidant treatments [no supplementation; vitamin E; Agrado; vitamin E plus Agrado]. Ten strip loins from each treatment were collected, aged, cut into steaks, and placed under retail display. Tenderness, free calcium, sarcomere lengths, proteolysis, and SR membrane phospholipid and fatty acid profiles were measured. The 30% WDGS diet increased (P < 0.05) total PUFA in the SR membrane. Steaks from steers fed 30% WDGS without an antioxidant had more (P = 0.05) phosphatidylcholine in the SR membrane but less (P < 0.05) phosphatidylethanolamine compared with steaks from steers fed 0% WDGS only or 30% WDGS supplemented with vitamin E. At 2 d postmortem, steaks from steers fed 30% WDGS had more (P < 0.05) proteolysis compared with steaks from steers fed 0% WDGS. There were no differences in tenderness, sarcomere length, or free calcium among treatments in any of the aging or display periods (P > 0.10). These results suggest that the alteration of SR membrane fatty acid profile in WDGS-fed cattle may affect the ratio of SR membrane phospholipids, creating membrane instability, and thereby increasing proteolysis, whereas feeding vitamin E mitigates such effects.