Quality effects on beef strip steaks from cattle fed high-protein corn distillers grains and other ethanol by-products

Nutritional Performance of Grazing Beef Cattle Supplemented with High-Protein Distillers' Dried Grain

The objective was to evaluate the effects of including high-protein distillers dried grains (HP-DDG; 430 g/CP) in supplements for beef cattle in an intensive finishing pasture system. Five Nellore bulls with an average body weight (BW) of 413.5 ± 32 kg were distributed in a 5 × 5 Latin square design. The animals were randomly allocated to Marandu palisade grass paddocks (Urochloa brizantha cv. Marandu), with 0.32 ha each. Protein-energy supplements were evaluated and formulated with different replacement levels (0, 250, 500, 750 and 1000 g/kg) of soybean meal (SBM) by HP-DDG. Supplements were offered once a day in the amount of 6.0 kg/animal. Replacing SBM with HP-DDG had no effect (p > 0.10) on the intake of total and pasture DM, OM, CP, NDFap, digestible organic matter (DOM), metabolizable protein and CP:DOM ratio. Total and pasture DM intake averaged 6.07 and 11.54 kg/day, respectively. Replacing SBM with HP-DDG reduces and increases, respectively, the intake of degradable (RDP) and undegradable (RUP) protein in the rumen (p < 0.10) with a consequent linear reduction in ruminal ammonia concentration (RAN), nitrogen excretion in urine and serum N concentration (SUN) (p < 0.10). In supplements offered in the amount of 6.0 kg animal/day, SBM can be completely replaced by HP-DDG.

Animal performance and meat quality characteristics from feedlot-finished steers fed increasing levels of wet distillers grain

One hundred forty-four steers were group-housed in 24 pens that were randomly assigned to one of four dietary treatments defined by the proportion of wet distiller grain plus solubles (WDGS; 0, 15, 30, or 45%) and fed for 84 d pre-slaughter. Animal performance was evaluated using the pen as the experimental unit. Whereas for carcass and meat quality characteristics, meat oxidative stability, and the consumer sensory quality of longissimus thoracis muscle one animal from each pen was randomly selected and used as the experimental unit. No differences (P > 0.05) were observed for subcutaneous fat thickness, rib eye area, marbling score or pH, color parameters, proximate composition, sarcomere length, Warner Bratzler shear force, and cooking loss. Feeding WDGS linearly increased total PUFA (P = 0.05), C18:2 n-6 (P = 0.004) proportions, and n-6/n-3 ratio (P < 0.01) but reduced C16:1 to C18:0 ratio (P < 0.01). Lipid oxidation was greater in beef from steers fed 30% and 45% WDGS (P = 0.05). Dietary WDGS linearly improved (P < 0.05) flavor and overall linking score in the consumer sensory panel.

Meat Quality and Muscle Tissue Proteome of Crossbred Bulls Finished under Feedlot Using Wet Distiller Grains By-Product

Wet distiller grains (WDG) are a corn by-product rich in protein and fiber that can be used in feedlot diets. This study evaluated F1 Angus-Nellore bulls fed on a control diet vs. WDG (n = 25/treatment). After a period of 129 days on these feeds, the animals were slaughtered and Longissimus thoracis samples were collected for both a meat quality evaluation and gel-based proteomic analyses. A greater ribeye area (99.47 cm²) and higher carcass weight (333.6 kg) (p < 0.05) were observed in the WDG-finished cattle compared to the control (80.7 cm²; 306.3 kg). Furthermore, there were differences (p < 0.05) in the intramuscular fat between the WDG and control animals (IMF = 2.77 vs. 4.19%), which led to a significant decrease (p < 0.05) in saturated fatty acids (FA). However, no differences (p > 0.10) were observed in terms of tenderness, evaluated using Warner–Bratzler shear force (WBSF). The proteomic and bioinformatic analyses revealed substantial changes in the biological processes, molecular functions, and cellular components of the WDG-finished cattle compared to the control. Proteins related to a myriad of interconnected pathways, such as contractile and structural pathways, energy metabolism, oxidative stress and cell redox homeostasis, and transport and signaling. In this experiment, the use of WDG supplementation influenced the protein expression of several proteins, some of which are known biomarkers of beef quality (tenderness and color), as well as the protein–protein interactions that can act as the origins of increases in muscle growth and reductions in IMF deposition. However, despite the effects on the proteome, the tenderness, evaluated by WBSF, and fatty acid profile were not compromised by WDG supplementation.

Oxidative stress and postmortem meat quality in crossbred lambs

The objective of this study was to evaluate effects of different levels of lipopolysaccharide (LPS)-mediated oxidative stress on fresh meat quality. Crossbred lambs (n = 29) were blocked by weight and fed a standard finishing ration for the duration of the study. Lambs were individually housed and treatment groups were administered one of three intravenous injections every 72 h across a three-injection (9-day) cycle: saline control (control), 50 ng LPS/kg body weight (BW) (LPS50), or 100 ng LPS/kg BW (LPS100). Rectal temperatures were measured to indicate inflammatory response. Lambs were harvested at the Loeffel Meat Laboratory and 80 mg of pre-rigor Longissimus lumborum were collected in control and LPS100 treatments within 30 min postmortem for RNA analysis. Wholesale loins were split and randomly assigned 1 or 14 d of wet aging. Chops were fabricated after aging and placed under retail display (RD) for 0 or 7 d. Animal was the experimental unit. LPS-treated lambs had increased (P < 0.05) rectal temperatures at 1, 2, 4, and 24 h post-injection. Transcriptomics revealed significant (Praw < 0.05) upregulation in RNA pathways related to generation of oxidative stress in LPS100 compared with control. A trend was found for tenderness (Warner-Bratzler shear force, WBSF; P = 0.10), chops from LPS50 having lower shear force compared with control at 1 d postmortem. Muscle from LPS50 treatment lambs exhibited greater troponin T degradation (P = 0.02) compared with all treatments at 1 d. Aging decreased WBSF (P < 0.0001), increased sarcoplasmic calcium concentration (P < 0.0001), pH (P < 0.0001), and proteolysis (P < 0.0001) across treatments. Following aging, chops increased discoloration as RD increased (P < 0.0001), with control chops aged 14 d being the most discolored. Chops from lambs given LPS had higher (P < 0.05) a* values compared with control at 14 d of aging. The L* values were greater (P < 0.05) in LPS100 compared with both LPS50 and control. Aging tended (P = 0.0608) to increase lipid oxidation during RD across either aging period. No significant differences (P > 0.05) in sarcomere length, proximate composition, fatty acid composition, or isoprostane content were found. These results suggest that defined upregulation of oxidative stress has no detriment on fresh meat color, but may alter biological pathways responsible for muscle stress response, apoptosis, and enzymatic processes, resulting in changes in tenderness early postmortem.

Characterizing membrane phospholipid hydrolysis of pork loins throughout three aging periods

Three chops from 20 pork carcasses were aged for 1, 8, and 21 days. Electrospray ionization-tandem mass spectrometry was used to comprehensively analyze profiles of phospholipids from each sample (n = 60). Total phospholipid quantity decreased 4-folds (P < .01) from 1 to 21 days of aging in pork loins. Phosphatidylinositol (PI) and phosphatidylserine (PS) increased by 30% and 73%, respectively, from 1 to 21 days of aging in pork loins (P < .01). This increase was mainly due to relative percentage increase from PI 38:4 (18:0-20:4) and PS 36:2 (18:0-18:2; P < .01). The results also showed that the relative percentage of lysophosphatidylcholine increased by 35% after short term aging (8d), and phosphatidic acid increased by 10-folds after extended aging (21d; P < .01). These results documented that phospholipids undergo enzymatic hydrolysis during aging, but also indicated that lipid species containing 18:2 or 20:4 within PI and PS were slightly more resistant to enzymatic hydrolysis compared with the other phospholipids.