Feeding wet distillers grains plus solubles contributes to sarcoplasmic reticulum membrane instability

Abstract

Abstract. Feeding wet distillers grains plus solubles (WDGS) increases polyunsaturated fatty acid (PUFA) levels in beef. It was hypothesised that WDGS in feedlot diets increases PUFA concentration in the sarcoplasmic reticulum (SR) membrane, thereby altering membrane integrity, resulting in more rapid intracellular calcium leakage and improved tenderness. The objective of this study was to evaluate this hypothesis. Ninety-six crossbred steers were fed either a corn-based diet with 0% WDGS or 50% WDGS. Fifteen strip loins per treatment were collected, fabricated into steaks, aged and placed under retail display conditions. Steaks were used to measure tenderness, proteolysis, free calcium concentrations, lipid oxidation, sarcomere length and SR membrane fatty acid, phospholipid lipid, neutral lipid and total lipid profiles. Compared with steaks from steers fed 0% WDGS, steaks from steers fed 50% WDGS were more tender (P < 0.05) and had greater (P < 0.05) free calcium concentrations early post-mortem. Feeding 50% WDGS also tended to increase (P < 0.10) total PUFA concentrations, decrease (P < 0.10) total phospholipid concentration and increase (P < 0.10) total neutral lipid concentration for SR membrane. Steaks from steers fed 0% WDGS had greater (P < 0.05) lipid oxidation (TBARS values) than steaks from steers fed 50% WDGS after extended aging. Although differences in tenderness between the two treatments were detected, there were no corresponding differences (P > 0.10) in sarcomere length or proteolysis. This study showed that feeding WDGS may increase tenderness, possibly by increasing free calcium in muscle early post-mortem. However, the true mechanism that contributes to these differences is still unclear.

Feeding distillers grains to cattle may affect beef tenderness early postmortem1

“…The average sarcomere length of strip loins from cattle fed corn-only, de-oiled MDGS, de-oiled MDGS plus corn oil, and full-fat MDGS were 1.77, 1.76, 1.75, and 1.76 μm, respectively. In agreement with our results, no differences in sarcomere length have been reported in studies on feeding distillers grains (Oltra et al, 2008: Chao et al, 2017a, 2017b.…”

“…No differences in troponin-T degradation were found between dietary treatments 2 d postmortem (P = 0.60; Table 3). In agreement with our results, Chao et al (2017a) showed that the inclusion of 50% WDGS in finishing diets did not affect troponin-T degradation when compared with diets with no addition of WDGS in any of the aging periods studied: 2, 7, 14, or 21. Conversely, Chao et al (2017b) indicated that feeding 40% WDGS increased troponin-T degradation at 2 d of aging compared with no addition of WDGS.…”

“…Several studies have found that beef from cattle fed distillers grains was more tender than beef from steers fed corn (Depenbusch et al, 2009;Segers et al, 2011;Senaratne, 2012;Chao et al, 2017a). Interestingly, opposite results were found when antioxidants were added in the diet.…”

“…Senaratne (2012) observed a trend (P = 0.06) that feeding 30% WDGS increased beef tenderness compared to feeding corn. Furthermore, Chao et al (2017a) reported that steaks from steers finished on WDGS were more tender than steaks from steers finished on corn at 2 d of aging. The tenderness data from these studies are in agreement with our results and support our hypothesis that feeding MDGS at high rates could increase beef tenderness early postmortem.…”

“…times more fat and protein than corn (Klopfenstein et al, 2008). Research has shown that feeding distillers grains to cattle could not only increase the concentration of polyunsaturated fatty acids (PUFA) in meat (Mello et al, 2012b;Domenech-Pérez et al, 2017;de Mello et al, 2018;Ribeiro et al, 2018) but also increase PUFA content of the sarcoplasmic reticulum (SR) membrane (Chao, 2017a). The mechanism of meat tenderization is a well-understood subject.…”