Our hypothesis was WDGS in feedlot diets increased polyunsaturated fatty acids (PUFA) concentration in the membrane of a calcium-holding organelle inside the cell, making the organelle membrane less stable. An unstable organelle membrane might result in more rapid calcium leakage post-rigor and thus improve tenderness through improved activation of calcium-dependent proteolytic enzymes (the calpain system).
To test our theory, 96 steers were finished on either an all-corn or 50 percent WDGS diet. Fifteen strip loins from each treatment were collected, aged and displayed under retail conditions. We measured tenderness, proteolysis, free calcium concentrations and lipid oxidation. The fatty acid, lipid and phospholipid profiles of the calcium holding organelle were also determined.