Supranutritional supplementation of vitamin E influences mitochondrial proteome profile of post-mortem longissimus lumborum from feedlot heifers

Supplementation of vitamin E improves beef colour stability by minimizing lipid oxidation-induced myoglobin oxidation. Mitochondria affect myoglobin redox stability, and dietary vitamin E influences mitochondrial functionality in skeletal muscles. Nonetheless, the influence of vitamin E on the mitochondrial proteome of beef skeletal muscles has yet to be  investigated. Therefore, the objective of this study was to examine the effect of dietary vitamin E on mitochondrial proteome of post-mortem beef longissimus lumborum (LL) muscle. Beef LL muscle samples (24 hours post-mortem) were obtained from the carcasses of nine (n = 9) vitamin E-fed (VITE) (1000 IU vitamin E for 89 days) and nine (n = 9) control (CONT) (diet without supplemental vitamin E) heifers. The mitochondrial proteome was analysed using two-dimensional gel electrophoresis and mass spectrometry, and nine differentially abundant spots were identified. All the differentially abundant spots were over-abundant in CONT, and the proteins were electron transport chain enzymes (NADH dehydrogenase iron-sulphur protein 8, NADH dehydrogenase flavoprotein 2, and cytochrome c oxidase subunit 5B), metabolic enzymes (succinate-CoA ligase (ADP-forming) subunit beta; dihydrolipoyllysine-residue succinyltransferase component of 2-oxoglutarate dehydrogenase complex; pyruvate dehydrogenase protein X component), and enzymes involved in ATP regeneration (creatine kinase S-type). The low abundance of these proteins in VITE may decrease mitochondrial activity, resulting in low oxidative activity. These findings suggest that the strong antioxidant activity of vitamin E leads to less expression of mitochondrial oxidative enzymes in beef skeletal muscles.Keywords: Beef colour, lipid oxidation, mitochondrial enzyme

Ractopamine-induced changes in the proteome of post-mortem beef longissimus lumborum muscle

Ractopamine is a beta-adrenergic agonist that is approved for use in beef cattle, pigs and turkeys as a repartitioning agent to increase lean muscle deposition and decrease lipogenesis. Although the effects of dietary ractopamine on the proteome profile of post-mortem pork muscles have been examined, its influence on beef muscle proteome has not been studied. Therefore, the objective of this study was to examine the effect of ractopamine on the proteome profile of post-mortem beef longissimus lumborum (LL) muscle. LL muscle samples were obtained from the carcasses of six (n = 6) steers fed ractopamine (RAC; 400 mg ractopamine hydrochloride for 28 days) and six (n = 6) steers fed no ractopamine (CON). The muscle proteome was analysed using two-dimensional gel electrophoresis and tandem mass spectrometry. Five differentially abundant spots were identified, and all the spots were over-abundant in RAC. The identified proteins were involved in muscle structure development (F-actin-capping protein subunit beta-2; PDZ and LIM domain protein-3), chaperone activity (heat shock protein beta-1), oxygen transport (myoglobin), and glycolysis (L-lactate dehydrogenase A chain). These results suggested that dietary ractopamine could influence the abundance of enzymes associated with muscle development and muscle fibre type shift in beef LL muscle.Keywords: growth promotants, meat quality, proteomic

Reorganization of Experiential Learning Activities into a Single Multi-Section Course

Encouraging students to engage in out-of-the-classroom learning experiences is a long-standing priority in the Department of Animal Sciences at the University of Illinois. Recently, experiential learning opportunities fulfilling this curriculum requirement were organized under one multi-section course. Students are required to complete a memorandum-of-agreement with a faculty supervisor outlining their proposed activity, learning objectives, and work product to demonstrate their learning. Considerable flexibility was maintained within this organization so that students can pursue a wide range of experiences. This reorganization provides the opportunity to evaluate the breadth of the students’ experiential learning activities. From the summer 2012 through spring 2013, 185 students (39% of the animal sciences majors) completed 238 experiences supervised by 38 different faculty supervisors. Students engaging in multiple experiences accounted for 17.7% of the total, with 14.3% engaging in 2 experiences and 3.4% engaging in 3 to 5 experiences. Students earned 1 (49.2%), 2 (29.8%), 3 (13.0%), or 4 hours (8.0%) of credit for experiences across an array of activities. The majority of experiences involved undergraduate research (33.2%). A substantial number of experiences reflected a companion or exotic animal interest including internships at a local county humane society (18.9%), companion animal spring break trip (13.4%), working with a veterinarian (8.0%) and interning at zoos, sanctuaries or rescue organizations (3.0%). Other experiences included teaching assistance in the required animal handling course (8.0%), on-campus special projects (4.2%) and internships with agriculture groups (1.7%) or companies (1.7%). Study abroad accounted for 3.8% of the experiences. Organization of diverse experiential learning opportunities under one course number with multiple sections provides important information about the range and nature of opportunities in which students engage. This allows the department to further enhance the value of experiential learning to its students.published or submitted for publicationis peer reviewe

Einfluss der Strahlqualität auf die Schwingfestigkeit laserstrahlgeschweißter Verbindungen

Das Laserstrahlschweißen hat als modernes Fügeverfahren in der industriellen Praxis ein breites Anwendungsfeld gefunden. Laserstrahlschweißverfahren zeichnen sich gegenüber konventionellen thermischen Fügeverfahren im Stahlbau (z.B. MSG-Schweißen) hauptsächlich durch die örtlich eng begrenzte Energieeinbringung sowie durch sehr hohe Leistungsdichten aus. Durch den Einsatz insbesondere moderner Laserstrahlquellen mit höchster Strahlqualität, wie Scheiben- oder Faserlaser, können solche Schweißverbindungen mit immer kleineren Fokusdurchmessern, größeren Schweißgeschwindigkeiten und -tiefen realisiert werden. Allerdings resultieren daraus auch verringerte Nahtbreiten, kleinere Kerbradien sowie reduzierte Abkühlzeiten und erhöhte Nahtaufhärtung (bei härtbaren Stahlgüten). Die Schweißnahtqualität (Nahtgeometrie, Kerbradius) und die lokalen Eigenschaften in der wärmebeeinflussten Fügezone bestimmen allerdings maßgeblich die Schwingfestigkeit der Verbindung, wobei der Einfluss mit sinkender Nahtbreite zunimmt. Die aktuellen Regelwerke und Richtlinien zur schwingfesten Auslegung schmelzgeschweißter Verbindungen enthalten keine gesonderten Ermüdungsfestigkeitswerte für strahlgeschweißte Verbindungen. Es ist daher zwingend erforderlich, die Ermüdungsfestigkeit von Laserstrahlschweißverbindungen unter Berücksichtigung wesentlicher schwingfestigkeitsrelevanter Qualitätsmerkmale (insbesondere Kantenversatz und Winkelverzug) grundlegend zu untersuchen