Myofibrillar Protein Turnover in Feed-Restricted and Realimented Beef Cattle

The objective of this study was to determine the effect of feed restriction and repletion on myofibrillar protein turnover in cattle. Crossbred steer calves (n = 12) about 310 d of age were assigned randomly to a diet of corn and silage that was 1) provided ad libitum for 146 d (ALC) or 2) restricted so steers gained .2 kg/d for 80 d but received ad libitum access to feed thereafter for 66 d (RFC). At 27, 55, 97, 118 and 146 d a 24-h urine sample and a blood sample were obtained. Urine was analyzed for Nτ-methylhistidine Nτ-MH), creatinine (C), urea nitrogen (UN) and total nitrogen (TN). Serum samples were analyzed for hydroxyproliine (HYF\u27), C and albumin (A). Body weights were lower (P \u3c .05) in RFC at 55, 97, 118 and 146 d. Excretion of Nτ-MH was lower (P \u3c .05) in the RFC at 27 and 55 d but higher at 118 d Urinary C excretion was higher in ALC at the last four sample times. Urinary UN and TN excretion were lower (P \u3c .05) in RFC at 55, 97 and 118 d; urinary UN also was lower (P \u3c .05) at d 146. Serum A was higher (P \u3c .05) in ALC at 55 and 118 d, respectively. Serum HYP was higher (P \u3c .05) in RFC at 27 and 55 d. Calculated myofibrillar protein breakdown rates (FBR) and fractional synthesis rates (FSR) were higher (P \u3c .05) in RFC at the last two sampling periods; FSR was lower for the RFC at the first sampling period. Realimentation after a period of feed restriction increased both synthesis and degradation of myofibrillar protein in beef cattle

Effects of Backgrounding and Growing Programs on Beef Carcass Quality and Yield

Clearly, the future of the beef cattle industry in the United States depends on the quality of the product. The majority of calves are born in the spring; therefore, to have a consistent supply of feeders entering feedlots and to take advantage of forages, a variety of stocker programs exist. Cattle enter the feedlot at varying weights and ages and from different nutritional backgrounds, and this variation could produce differences in carcass quality. The economically important measures of carcass quality are yield grade and quality grade. They are directly related: as cattle fatten in the feedlot, both quality grade and yield grade increase. Because cattle are commercially fed to fat-constant end points, it is logical to make comparisons at equal fat end points. Then, marbling (percentage Choice) becomes the primary quality criterion. We analyzed data from 534 cattle serially slaughtered and found that the percentage grading Choice increased 12 ± 1 percentage units for each 1-mm increase in rib fat. Marbling score increased 30 units (200 = slight 00) for each 1-mm increase in fat. To determine the effect of rate of winter gain on carcass quality, 372 calves over 5 yr were wintered at .23 or .61 kg/d gain. When adjusted to equal rib fat after summer grazing and finishing, there was no difference in quality grade. To test the effect of summer gain on carcass quality, 418 calves over 7 yr were followed through the feedlot after gaining .57 or .84 kg/d on grass. When compared at equal rib fat, there was no difference in quality grade. Shear force values and consumer taste panels were used to evaluate steaks from 90 cattle from calf-fed and yearling production systems. Calf-feds were 14 mo of age at slaughter and yearlings were 19 or 21 mo. Each group was serially slaughtered. There was no effect of an additional .39 cm of rib fat on shear force, juiciness, tenderness, flavor, or overall palatability. Calf-feds were significantly more tender than yearlings, but the risk of an undesirable steak from yearlings was \u3c .2% based on shear force and \u3c 2.8% based on the consumer taste panel. If cattle are fed to a common rib fat end point, and within the range of rates of winter and summer gains reported herein, we conclude that the backgrounding program has little or no effect on marbling or carcass quality grade

Brimonidine prevents axonal and somatic degeneration of retinal ganglion cell neurons

<p>Abstract</p> <p>Background</p> <p>Brimonidine is a common drug for lowering ocular pressure and may directly protect retinal ganglion cells in glaucoma. The disease involves early loss of retinal ganglion cell transport to brain targets followed by axonal and somatic degeneration. We examined whether brimonidine preserves ganglion cell axonal transport and abates degeneration in rats with elevated ocular pressure induced by laser cauterization of the episcleral veins.</p> <p>Results</p> <p>Ocular pressure was elevated unilaterally by 90% for a period of 8 weeks post- cauterization. During this time, brimonidine (1mg/kg/day) or vehicle (phosphate-buffered saline) was delivered systemically and continuously via subcutaneous pump. Animals received bilateral intravitreal injections of fluorescent cholera toxin subunit β (CTB) two days before sacrifice to assess anterograde transport. In retinas from the vehicle group, elevated pressure induced a 44% decrease in the fraction of ganglion cells with intact uptake of CTB and a 14-42% reduction in the number of immuno-labelled ganglion cell bodies, with the worst loss occurring nasally. Elevated pressure also caused a 33% loss of ganglion cell axons in vehicle optic nerves and a 70% decrease in CTB transport to the superior colliculus. Each of these components of ganglion cell degeneration was either prevented or significantly reduced in the brimonidine treatment group.</p> <p>Conclusions</p> <p>Continuous and systemic treatment with brimonidine by subcutaneous injection significantly improved retinal ganglion cell survival with exposure to elevated ocular pressure. This effect was most striking in the nasal region of the retina. Brimonidine treatment also preserved ganglion cell axon morphology, sampling density and total number in the optic nerve with elevated pressure. Consistent with improved outcome in the optic projection, brimonidine also significantly reduced the deficits in axonal transport to the superior colliculus associated with elevated ocular pressure. As transport deficits to and from retinal ganglion cell projection targets in the brain are relevant to the progression of glaucoma, the ability of brimonidine to preserve optic nerve axons and active transport suggests its neuroprotective effects are relevant not only at the cell body, but throughout the entire optic projection.</p

Hat-P-28b and Hat-P-29b: Two Sub-Jupiter Mass Transiting Planets

We present the discovery of two transiting exoplanets. HAT-P-28b orbits a V = 13.03 G3 dwarf star with a period P = 3.2572 days and has a mass of 0.63 ± 0.04 M_J and a radius of 1.21^(+0.11)_(–0.08) R_J yielding a mean density of 0.44 ± 0.09 g cm^(–3). HAT-P-29b orbits a V = 11.90 F8 dwarf star with a period P = 5.7232 days and has a mass of 0.78^(+0.08)_(–0.04) M_J and a radius of 1.11^(+0.14)_(–0.08) R_J yielding a mean density of 0.71 ± 0.18 g cm^(–3). We discuss the properties of these planets in the context of other known transiting planets

Consumer Sensory Acceptance and Value of Wet-Aged and Dry-Aged Beef Steaks

To determine sensory preference and value of fresh beef steak differing in aging technique, strip steaks were evaluated by consumers in Denver (n = 132 consumers) and Chicago (n = 141 consumers). Wet-aged Choice strip loins were matched with dry-aged Choice strip loins, whereas wet-aged Prime strip loins were matched with dry-aged Prime strip loins. Dry-aged strip loins were commercially aged in air in a controlled environment for 30 d and vacuum-aged for 7 d during shipping and storage. Wet-aged strip loins were vacuum-packaged and aged for 37 d in a 1°C cooler. Pairs of strip loins were matched to similar Warner- Bratzler shear force values and marbling scores. Twelve sensory evaluation panels (of 12 scheduled panelists each) were conducted over a 3-d period in each city. Individual samples from a pair of steaks were evaluated by the panelists for sensory traits. Bids were placed on the samples after sensory traits were obtained utilizing a variation of the Vickery auction with silent, sealed bids. No significant differences for sensory traits of flavor, juiciness, tenderness, or overall acceptability were detected between wet-aged Choice samples and dry-aged Choice samples. Although wet-aged Choice samples were numerically superior for all sensory traits, consumers placed similar bid values (P = 0.12) on wet- and dry-aged Choice samples ($3.82 per 0.45 kg and$3.57 per 0.45 kg, respectively). Wet-aged Prime samples were rated more desirable (P \u3c 0.001) for flavor, tenderness, and overall acceptability than dry-aged Prime samples. Wet-aged Prime samples were valued at $4.02 per 0.45 kg, whereas dry-aged Prime samples brought$3.58 per 0.45 kg (P = 0.008). Consumers (29.3%) who preferred the dry-aged Choice samples over the wet-aged Choice samples were willing to pay $1.99/0.45 kg more (P \u3c 0.001) for dry-aged samples. The consumers who preferred the wet-aged Choice over the dry-aged Choice samples (39.2$1.77/0.45 kg more (P \u3c 0.0001). Consumers who preferred wet-aged Prime over dry-aged Prime samples (45.8%) paid $1.92/0.45 kg more (P \u3c 0.0001). Consumers who preferred dry-aged Prime samples (27.5$1.92/0.45 kg more than for the wet-aged Prime samples. Although more consumers preferred wet-aged samples, markets do exist for dry-aged beef, and consumers are willing to pay a premium for this product

Consumer Visual Preference and Value for Beef Steaks Differing in Marbling Level and Color

To determine visual preference and value for fresh beef steaks differing in marbling level and color, consumers in Chicago and San Francisco (n = 124 per city) evaluated two pairs of steaks in a retail case. Steaks differing in marbling level (Modest/ Moderate vs. Slight) and color (bright, cherry-red vs. dark red) were purchased at retail stores in each city. Consumers selected their preferred steak in each pair, described their selection criteria, and provided the price they were willing to pay for each of the four steaks. There was a difference in visual preference in each city, with most consumers preferring (P \u3c 0.01) low (Slight) over high (Moderate/Modest) marbling; however, more (P \u3c 0.01) consumers in Chicago (86.7%) preferred low marbling than in San Francisco (67.0%). Selection criteria were categorized into five groups: marbling, fat, color, appearance, and palatability. Marbling was mentioned by 65.4% of consumers who preferred high marbling, whereas 64.9% of consumers who preferred low marbling mentioned fat as a selection criterion. Bright, cherry-red color was preferred by a higher (P \u3c 0.01) percentage of consumers in both Chicago and San Francisco (67.6 and 76.5%, respectively). Color was mentioned both by consumers who preferred bright, cherry-red color (64.8%) and those who preferred dark red color (63.9%). All preference groups were willing to pay more for their preferred steak (P \u3c 0.01), but consumers who preferred low marbling were willing to pay more (P \u3c 0.01) for their preferred steak than consumers who preferred high marbling. Consumers who preferred bright, cherry-red color were willing to pay more (P \u3c 0.01) for their preferred steak than consumers who preferred dark red color. Consumers who preferred low marbling seemed to desire lean products, and consumers who preferred high marbling seemed to desire products with high eating quality. In this study, consumers were willing to pay more to purchase their preferred product; however, most consumers preferred low marbling and bright, cherry-red color

Two 'b's in the Beehive: The Discovery of the First Hot Jupiters in an Open Cluster

We present the discovery of two giant planets orbiting stars in Praesepe (also known as the Beehive Cluster). These are the first known hot Jupiters in an open cluster and the only planets known to orbit Sun-like, main-sequence stars in a cluster. The planets are detected from Doppler shifted radial velocities; line bisector spans and activity indices show no correlation with orbital phase, confirming the variations are caused by planetary companions. Pr0201b orbits a V=10.52 late F dwarf with a period of 4.4264 +/- 0.0070 days and has a minimum mass of 0.540 +/- 0.039 Mjup, and Pr0211b orbits a V=12.06 late G dwarf with a period of 2.1451 +/- 0.0012 days and has a minimum mass of 1.844 +/- 0.064 Mjup. The detection of 2 planets among 53 single members surveyed establishes a lower limit on the hot Jupiter frequency of 3.8 (+5.0)(-2.4) % in this metal-rich open cluster. Given the precisely known age of the cluster, this discovery also demonstrates that, in at least 2 cases, giant planet migration occurred within 600 Myr after formation. As we endeavor to learn more about the frequency and formation history of planets, environments with well-determined properties -- such as open clusters like Praesepe -- may provide essential clues to this end.Comment: 5 pages, 3 tables, 2 figures. Published in ApJ Letter

Parenting and toddler self‐regulation in low‐income families: What does sleep have to do with it?

Toddlerhood is a sensitive period in the development of self‐regulation, a set of adaptive skills that are fundamental to mental health and partly shaped by parenting. Healthy sleep is known to be critical for self‐regulation; yet, the degree to which child sleep alters interactive child–parent processes remains understudied. This study examines associations between observed parenting and toddler self‐regulation, with toddler sleep as a moderator of this association. Toddlers in low‐income families (N = 171) and their mothers were videotaped during free play and a self‐regulation challenge task; videos were coded for mothers’ behavior and affect (free play) and toddlers’ self‐regulation (challenge task). Mothers reported their child’s nighttime sleep duration via questionnaire. Results revealed significant Sleep × Maternal Negative Affect and Sleep × Maternal Negative Control interactions. Children who did not experience negative parenting had good self‐regulation regardless of their nighttime sleep duration. For children who did experience negative parenting, self‐regulation was intact among those who obtained more nighttime sleep, but significantly poorer among children who were getting less nighttime sleep. Thus, among children who were reported to obtain less nighttime sleep, there were more robust associations between negative parenting and poorer self‐regulation than among toddlers who were reported to obtain more sleep.RESUMENLos primeros años de la niñez son un período sensible en el desarrollo de la auto‐regulación, un grupo de habilidades adaptables que son fundamentales para la salud mental y a las que en parte les da forma la crianza. Es sabido que el dormir bien es esencial para la auto‐regulación y, aun así, el nivel al que el sueño del niño altera los procesos interactivos entre progenitor y niño permanece poco estudiado. Este estudio examina las asociaciones entre la crianza observada y la auto‐regulación del niño pequeño, tomando como moderador de tal asociación el proceso de dormir del niño pequeño. Se grabó en video a niños pequeños de familias de bajos ingresos (N=171) y sus madres durante una sesión de juego libre y una tarea de auto‐regulación que suponía un reto; los videos fueron codificados en cuanto al comportamiento y afecto de las madres (juego libre) y la auto‐regulación de los niños pequeños (tarea que suponía reto). Las madres reportaron acerca del sueño nocturno de sus niños por medio de un cuestionario. Los resultados revelaron interacciones significativas en cuanto al dormir y el negativo afecto materno, así como el dormir y el negativo control materno. Los niños que no experimentaron una crianza negativa tenían una buena auto‐regulación independientemente de la duración de su sueño nocturno. En el caso de los niños que experimentaron una crianza negativa, la auto‐regulación quedó intacta en aquellos que lograban más tiempo nocturno de dormir, pero fue significativamente más pobre en los niños que tenían menos tiempo de sueño nocturno. Por tanto, en el caso de los niños indicados en el reporte con menos tiempo de dormir nocturno, se dieron asociaciones más robustas entre la crianza negativa y una más pobre auto‐regulación que entre los niños pequeños indicados en el reporte con más tiempo de dormir.RÉSUMÉLa petite enfance est une période sensible dans le développement de l’auto‐régulation, un ensemble de compétences qui sont fondamentales pour la santé mentale et en partie formées par le parentage. L’on sait qu’un sommeil sain est critique pour l’auto‐régulation et pourtant la mesure dans laquelle le sommeil de l’enfant altère les processus interactifs enfant‐parent demeure peu étudiée. Cette étude examine les liens entre le parentage observé et l’auto‐régulation du petit enfant, le sommeil de l’enfant ayant un effet modérateur dans ce lien. Des jeunes enfants de familles issues de milieux défavorisés (N=171) et leurs mères ont été filmés durant un jeu libre et un exercice de défi d’auto‐régulation. Les vidéos ont été codées pour le comportement des mères et l’affect (jeu libre) et l’auto‐régulation des jeunes enfants (exercice de défi). Les mères ont fait état de la durée de sommeil nocturne de leur enfant au moyen d’un questionnaire. Les résultats ont révélé que : sommeil significatif x l’affect négatif maternel et le sommeil x négatif maternel contrôle les interactions. Les enfants qui n’avaient pas fait l’expérience d’un parentage négatif avaient une bonne auto‐régulation quelle qu’ait été la durée du sommeil nocturne. Pour les enfants ayant fait l’expérience d’une parentage négatif, l’auto‐régulation était intacte chez ceux ayant plus dormi, mais bien moindre chez les enfants qui avaient moins dormi. Donc, chez les enfants ayant moins de sommeil nocturne les liens bien plus robustes ont été découverts entre le parentage négatif et une moindre auto‐régulation que chez les petits enfants dormant plus durant la nuit.ZUSAMMENFASSUNGDas Kleinkindalter ist ein sensibler Zeitraum für die Entwicklung der Selbstregulation – einer Reihe von Anpassungsfähigkeiten, die für die psychische Gesundheit grundlegend sind und teilweise durch Erziehung geprägt werden. Gesunder Schlaf ist bekanntlich entscheidend für die Selbstregulation, aber das Ausmaß, in dem der Kinderschlaf interaktive Prozesse zwischen Kind und Eltern verändert, ist bisher nur unzureichend erforscht wurden. Diese Studie untersucht Zusammenhänge zwischen beobachtetem Erziehungsverhalten und der Selbstregulation von Kleinkindern, wobei der Schlaf der Kleinkinder als Moderator dieser Assoziation fungiert. Kleinkinder aus einkommensschwachen Familien (N=171) und ihre Mütter wurden während des freien Spiels und einer herausfordernden Aufgabe zur Selbstregulation gefilmt; die Videos wurden für das Verhalten und die Affekte der Mütter (freies Spiel) und die Selbstregulation der Kleinkinder (herausfordernde Aufgabe) kodiert. Die Mütter berichteten per Fragebogen über die nächtliche Schlafdauer ihres Kindes. Die Ergebnisse zeigten signifikante Interaktionen für Schlaf und mütterlichen negativen Affekt sowie für Schlaf und mütterliche negative Kontrollinteraktionen. Kinder, die keine negative Erziehung erlebten, hatten eine gute Selbstregulation, unabhängig von ihrer nächtlichen Schlafdauer. Bei Kindern, die eine negative Erziehung erfuhren, war die Selbstregulation bei denen, die mehr Nachtschlaf erhielten, intakt und bei Kindern, die weniger Nachtschlaf erhielten, jedoch deutlich schlechter. So gab es bei Kindern, von denen berichtet wurde, dass sie weniger Nachtschlaf erhielten, robustere Assoziationen zwischen negativer Erziehung und schlechterer Selbstregulation als bei Kleinkindern, von denen berichtet wurde, dass sie mehr Schlaf erhielten.抄録低収入家庭における子育てと幼児の自己調整力:睡眠が関与するものとは何か？幼児期は、自己調整力、つまりメンタルヘルスの基礎であり、ある程度までは子育てによって形成される、一連の適応スキルの発達が影響を受けやすい時期である。健康的な睡眠は自己調整力には不可欠のものとして知られているが、子どもの睡眠が子どもと親の相互作用の過程をどの程度まで改めるかについては、いまもなお研究課題のままである。本研究は、観察によって得られた子育てと幼児の自己調整力の関連性について幼児の睡眠を仲介として検討することである。低所得家庭 (N=171) で生活している幼児と母親が自由遊びと自己調整のチャレンジタスクに取り組む間中ビデオ録画した。ビデオデータは母親の行動と感情(自由遊び)と幼児の自己調整力(チャレンジタスク)としてコード化された。子どもの夜間の睡眠時間は母親からの質問紙を通して報告された。その結果、睡眠と母親の否定的感情の間、そして睡眠と母親の否定的コントロールの間には著しい相互関連性が認められた。否定的育児を経験していない子どもは、夜間の睡眠時間に関わらず、よい自己調整力を持っていた。否定的育児を経験した子どもでは、自己調整力はより長い夜間睡眠をとっている子どもにおいては保たれていたが、より短い睡眠時間しかとっていない子どもにおいては著しく低かった。このようにより短い睡眠時間しかとっていないと報告された子どもにおいては、より長い睡眠をとっている幼児より、否定的育児とより低い自己調整力の間により確かな関連性が示された。摘要低收入家庭的育兒和幼兒自我調節:與睡眠有什麼關係？幼兒期是自我調節發展的一個敏感時期， 這是一套適應性技能， 是心理健康的基礎， 部分由養育方式塑造。眾所周知， 健康睡眠對於自我調節至關重要， 然而， 兒童睡眠如何改變兒童 ‐ 父母互動仍未得到充分研究。本研究探討觀察到的養育方式與幼兒自我調節的關聯， 及幼兒睡眠作為這種關聯的調節變數。低收入家庭的幼兒 （N = 171） 和母親在自由遊戲和自我調節挑戰任務中被錄像; 視頻被編碼為母親的行為和情感 （自由遊戲） 和幼兒的自我調節 （挑戰任務）。母親通過問卷報告孩子的夜間睡眠時間。結果顯示顯著的睡眠x母體負面情感和睡眠 x 母體負面控制相互作用。沒有經歷負面養育的孩子， 無論夜間睡眠時間長短， 都有良好的自我調節能力。對於那些經歷過負面養育的孩子， 在夜間睡眠較多的人中， 自我調節是完整的， 但在夜間睡眠較少的孩子中， 自我調節顯著較差。因此， 在夜間睡眠較少的兒童中， 負面育兒和較差的自我調節的關聯性強於較多睡眠的幼兒。ملخصالرعاية الوالدية والتنظيم الذاتي للطفل في الأسر ذات الدخل المنخفض: ما علاقة النوم بذلك ؟الطفولة هي فتره حساسة في تطوير التنظيم الذاتي ، والذي يمثل مجموعه من المهارات التكيفيه التي هي أساسيه للصحة النفسية وتتشكل جزئيا عن طريق الأبوه والأمومه. ومن المعروف ان النوم الصحي أمر بالغ الاهميه للتنظيم الذاتي ، ومع ذلك ، فان الدرجة التي يغير بها نوم الطفل في العمليات التفاعلية التي يقوم بها الطفل مع الوالدين لا تزال غير خاضعة للدراسة الكافية. تتناول هذه الدراسة العلاقات بين الرعاية الوالدية الملحوظة والتنظيم الذاتي للطفل الصغير ، حيث نوم الطفل يمثل المتغير الوسيط في هذه العلاقة. اشترك في الدراسة مجموعة من الأطفال الصغار في الأسر ذات الدخل المنخفض (العدد = 171) وأمهاتهم وتم تصويرهم بالفيديو اثناء اللعب الحر مع تكليفهم بمهمة تحدي التنظيم الذاتي ؛ تم ترميز تسجيلات الفيديو لسلوك الأمهات وعاطفتهم في (اللعب الحر) والتنظيم الذاتي للأطفال الصغار في (مهمة التحدي). وأبلغت الأمهات عن مده النوم الليلي لأطفالهن عن طريق الاستبيان. أظهرت النتائج تفاعلات ذات دلالة إحصائية بين النوم والعاطفة السلبية عند الأمهات وبين النوم والسيطرة السلبية للأمهات . الأطفال الذين لا يعانون من الابوه والامومه السلبية كان لديهم قدرات جيدة على التنظيم الذاتي بغض النظر عن مده النوم ليلا. بالنسبة للأطفال الذين يعانون من الابوه والامومه السلبية ، كان التنظيم الذاتي سليما بين أولئك الذين حصلوا علي المزيد من النوم ليلا ، ولكن أضعف بكثير بين الأطفال الذين كانوا يحصلون علي اقل النوم ليلا. وبالتالي ، فانه من بين الأطفال الذين ابلغ عن حصولهم علي قسط اقل من النوم الليلي ، كانت هناك رابطات اقوي بين الرعاية الوالدية السلبية والتنظيم الذاتي الأقل منها بين الصغار الذين أفيد بأنهم يحصلون علي المزيد من النوم.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150525/1/imhj21783.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150525/2/imhj21783_am.pd

HAT-P-56b: An inflated massive Hot Jupiter transiting a bright F star followed up with K2 Campaign 0 observations

We report the discovery of HAT-P-56b by the HATNet survey, an inflated hot Jupiter transiting a bright F type star in Field 0 of NASA's K2 mission. We combine ground-based discovery and follow-up light curves with high precision photometry from K2, as well as ground-based radial velocities from TRES on the FLWO 1.5m telescope to determine the physical properties of this system. HAT-P-56b has a mass of $2.18 M_J$, radius of $1.47 R_J$, and transits its host star on a near-grazing orbit with a period of 2.7908 d. The radius of HAT-P-56b is among the largest known for a planet with $M_p > 2 M_J$. The host star has a V-band magnitude of 10.9, mass of 1.30 $M_\odot$, and radius of 1.43 $R_\odot$. The periodogram of the K2 light curve suggests the star is a $\gamma$ Dor variable. HAT-P-56b is an example of a ground-based discovery of a transiting planet, where space-based observations greatly improve the confidence in the confirmation of its planetary nature, and also improve the accuracy of the planetary parameters.Comment: 13 pages, 11 figures, accepted by A

The Influence of Diet and Oxidation on Calcium Retention of the Mitochondria in Fresh Beef

Feeding dried distillers grains (DG) may influence calcium flux postmortem by disrupting the stability of the sarcoplasmic reticulum (SR) membrane, thus leading to a higher post- rigor calcium leakage, resulting in greater activation of calpains and improved tenderness. Mitochondria provide the opportunity to study calcium flux in a controlled, tightly defined environment as a model system for the SR. Cattle were finished on diets containing either 0% DG or 50% DG. Feeding DG increased proportions of PUFA in the SR and mitochondrial membrane. Oxidized mitochondria retained less calcium than non- oxidized mitochondria. Mitochondria from cattle finished on corn tended to retain more Ca than mitochondria from cattle finished on DG. These findings suggest that feeding DG in the finishing diet can possibly increase meat tenderness through altered calcium flux