Date of this Version
Chao, M. D. 2015. Impact of wet distillers grains plus solubles and antioxidants on a basic mechanism of beef tenderization. Dissertation, University of Nebraska-Lincoln, DigitalCommons.
Feeding high levels of wet distillers grains plus solubles (WDGS) increases polyunsaturated fatty acid (PUFA) levels in beef. Perhaps, WDGS in feedlot diets increases PUFA concentration in the SR membrane, thereby altering membrane integrity, resulting in more rapid calcium leakage and improved tenderness. Feeding antioxidants may mitigate such effects. In the first study, effects of feeding 50 % WDGS on SR membrane composition, free calcium concentration and tenderness were studied. The SR membrane from steers fed WDGS were more tender, had higher free calcium concentration, had more PUFA, more phosphatidylcholine (PC), less phosphatidylethanolamine (PE) and less total phospholipids when compared to SR membrane from steers fed corn-only (P < 0.05). In the second study, effects of feeding 30% WDGS and two antioxidants on muscle tissue fatty acid profiles, color and lipid oxidation of beef were studied. Steaks from cattle fed WDGS had increased muscle tissue PUFA, were not different in color, and were less oxidized when compared to steaks from steers fed corn-only (P < 0.05). Supplementing vitamin E (E) was very effective in reducing discoloration and lipid oxidation, and increasing muscle tissue E levels compared to the diets without E supplementation (P < 0.05). Feeding Agrado Plus (AG) had minimal effect of discoloration and lipid oxidation, but significantly increased muscle tissue ethoxyquin level compared to diets without AG supplementation. In the third study, effects of feeding WDGS and the two antioxidants on SR membrane composition and proteolysis were studied. Again, feeding WDGS increased total PUFA and PC, but decreased PE in the SR membrane (P < 0.05). Conversely, E supplementation in WDGS diet prevented such shifts, while supplementing AG in the corn-only diet created similar effects as the WDGS-only diet for SR membrane phospholipid profile. At 2 d postmortem, steaks from steers fed WDGS had more troponin-T degradation compared to steaks from steers fed corn-only or either diet supplemented with E only (P < 0.05). Feeding WDGS induced SR membrane phospholipid shift and clearly contributed to cattle SR membrane instability, while E supplementation may prevent such phenomenon.
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