Oceanic Residual Depth Measurements, the Plate Cooling Model and Global Dynamic Topography

Convective circulation of the mantle causes deflections of the Earth's surface that vary as a function of space and time. Accurate measurements of this dynamic topography are complicated by the need to isolate and remove other sources of elevation, arising from flexure and lithospheric isostasy. The complex architecture of continental lithosphere means that measurement of present-day dynamic topography is more straightforward in the oceanic realm. Here, we present an updated methodology for calculating oceanic residual bathymetry, which is a proxy for dynamic topography. Corrections are applied that account for the effects of sedimentary loading and compaction, for anomalous crustal thickness variations, for subsidence of oceanic lithosphere as a function of age, and for non-hydrostatic geoid height variations. Errors are formally propagated to estimate measurement uncertainties. We apply this methodology to a global database of 1,936 seismic surveys located on oceanic crust and generate 2,297 spot measurements of residual topography, including 1,161 with crustal corrections. The resultant anomalies have amplitudes of ±1 km and wavelengths of ∼1,000 km. Spectral analysis of our database using cross-validation demonstrates that spherical harmonics up to and including degree 30 (i.e. wavelengths down to 1,300 km) are required to accurately represent these observations. Truncation of the expansion at a lower maximum degree erroneously increases the amplitude of inferred long-wavelength dynamic topography. There is a strong correlation between our observations and free-air gravity anomalies, magmatism, ridge seismicity, vertical motions of adjacent rifted margins, and global tomographic models. We infer that shorter wavelength components of the observed pattern of dynamic topography may be attributable to the presence of thermal anomalies within the shallow asthenospheric mantle.This research is supported by a BP-Cambridge collaboration

Prédire à partir des pratiques d'élevage le rendement des carcasses et la tendreté de la noix d'entrecôte

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Prediction of beef carcass and meat traits from rearing factors in young bulls and cull cows

International audienceThe aim of this study was to predict the beef carcass and LM (thoracis part) characteristics and the sensory properties of the LM from rearing factors applied during the fattening period. Individual data from 995 animals (688 young bulls and 307 cull cows) in 15 experiments were used to establish prediction models. The data concerned rearing factors (13 variables), carcass characteristics (5 variables), LM characteristics (2 variables), and LM sensory properties (3 variables). In this study, 8 prediction models were established: dressing percentage and the proportions of fat tissue and muscle in the carcass to characterize the beef carcass; cross-sectional area of fibers (mean fiber area) and isocitrate dehydrogenase activity to characterize the LM; and, finally, overall tenderness, juiciness, and flavor intensity scores to characterize the LM sensory properties. A random effect was considered in each model: the breed for the prediction models for the carcass and LM characteristics and the trained taste panel for the prediction of the meat sensory properties. To evaluate the quality of prediction models, 3 criteria were measured: robustness, accuracy, and precision. The model was robust when the root mean square errors of prediction of calibration and validation sub-data sets were near to one another. Except for the mean fiber area model, the obtained predicted models were robust. The prediction models were considered to have a high accuracy when the mean prediction error (MPE) was ≤0.10 and to have a high precision when the was the closest to 1. The prediction of the characteristics of the carcass from the rearing factors had a high precision ( > 0.70) and a high prediction accuracy (MPE 0.10). Only the flavor intensity of the beef score could be satisfactorily predicted from the rearing factors with high precision ( = 0.72) and accuracy (MPE = 0.10). All the prediction models displayed different effects of the rearing factors according to animal categories (young bulls or cull cows). In consequence, these prediction models display the necessary adaption of rearing factors during the fattening period according to animal categories to optimize the carcass traits according to animal categories

Amélioration de la qualité sensorielle de la viande à l'aide des pratiques d'élevage

National audienceTo identify the benefic effects of breeding practices, for the fattening period, on the Longissimus Thoracis sensory properties, a dataset obtained from 329 young bulls (2 breed types: beef and hardy) was analyzed. Animals were classified in 2 clusters: high and low sensory quality of beef meat. Different breeding practices combinations driven to high sensory quality were highlighted with decision trees, according to breed types. A higher beef quality is possible with a forage intake ≥ 1.95 kg DM/d in the fattening diet and a fattening period duration < 178 d for young beef breed bulls. The slaughter age of young bulls had a positive impact on beef quality of hardy breeds (≥ 17.2 mo) and beef breeds (between 15.4 and 16.8 mo) if it was combined with a longer fattening period duration and a higher average daily gain, for beef breeds and in addition with a heavier weight for hardy breeds

Prediction of beef carcass and meat quality traits from factors characterising the rearing management system applied during the whole life of heifers

International audienceIn this study, four prediction models were developed by logistic regression using individual data from 96 heifers. Carcass and sensory rectos abdominis quality clusters were identified then predicted using the rearing factors data. The obtained models from rearing factors applied during the fattening period were compared to those characterising the heifers' whole life. The highest prediction power of carcass and meat quality clusters were obtained from the models considering the whole life, with success rates of 62.8% and 54.9%, respectively. Rearing factors applied during both pre-weaning and fattening periods influenced carcass and meat quality. According to models, carcass traits were improved when heifer's mother was older for first calving, calves ingested concentrates during pasture preceding weaning and heifers were slaughtered older. Meat traits were improved by the genetic of heifers' parents (i.e., calving ease and early muscularity) and when heifers were slaughtered older. A management of carcass and meat quality traits is possible at different periods of the heifers' life

Est-il possible de piloter conjointement les qualités de la carcasse et de la bavette de flanchet par les pratiques d’élevage, chez la génisse de race Charolaise en finition ?

National audienceThe aims of this study were to identify breeding practices during the fattening period that have the highest influence on carcass and beef meat sensory qualities in order to pilot simultaneously these two qualities, in Charolais heifers. One difficulty is that breeding practice is a combination of different livestock factor combinations. This study was performed on individual data from 111 heifers, during the fattening period. Available data concern livestock data (p=12), carcass characteristics (p=6) and flank steak (Rectus Abdominis) sensory proprieties. Four clusters representing four different breeding practices(J_leg, Fini_long, A_lourde and Conc_leg), were identified from two hierarchical ascendant classifications (HAC) established on quantitative (p=7) and qualitative (p=5) breeding data. These four clusters represent four different breeding practices. J_leg cluster (n=29) was mainly characterized by young slaughtered heifers (27.8 months), lightweight (635 kg) and low quantities of concentrates (CONC), UFL and PDI intake. Diet tended to be mainly based on hay. Fini_long cluster (n=26) was characterized by a long fattening period duration (220 days), heavier slaughtered heifers (700 kg) and low CONC, UFL and PDI intake. This cluster was also characterized by fattening grazing. A_lourde cluster (n=32) was characterized by older (36.3 months) and heavier (726 kg) slaughtered heifers. Fattening housing and diet with silage and/or straw characterized this breeding practice. Finally, the Conc_leg cluster (n=24) was characterized by lightweight slaughtered heifers (661 kg) and high CONC, UFL and PDI intake. The effects of the different breeding practice cluster on carcass characteristics and flank steak sensory properties were estimated by analysis of variance. Higher carcass quality was reached by breeding practice of the A_lourde cluster according to remuneration criteria (weight, conformation and fattening carcass) of the farmer. The breeding practice of the J_leg cluster enabled higher flank steak sensory properties. These two antagonist breeding practices show that it is difficult to simultaneously pilot carcass and beef meat quality, among Charolais heifers. During the fattening period, compromises should be found to avoid favoring one of these two qualities.Les objectifs de cette étude étaient d’identifier, chez la génisse de race Charolaise, les pratiques d’élevage en période de finition influençant le plus la qualité des carcasses et la qualité sensorielle de la viande dans le but de pouvoir piloter conjointement ces deux qualités. Une difficulté rencontrée est qu’une pratique d’élevage correspond à la combinaison de plusieurs facteurs d’élevage. L’étude a porté sur les données individuelles de 111 génisses en phase de finition. Les données à disposition concernent les données d’élevage (p=12), les caractéristiques de la carcasse (p=6) et les propriétés sensorielles (p=3) de la bavette de flanchet (Rectus Abdominis). Quatre classes, représentant quatre pratiques d’élevage différentes : J_leg, Fini_long, A_lourde et Conc_leg, ont été définies à partir de deux classifications ascendantes hiérarchiques (CAH) établies sur des données d’élevage quantitatives (p=7) et qualitatives (p=5). La classe J_leg (n=29) est caractérisée principalement par des génisses abattues jeunes (27,8 mois), légères (635 kg) et ingérant des quantités de concentrés (CONC), d’UFL et de PDI faibles. La ration a tendance à être principalement à base de foin. La classe Fini_long (n=26) se caractérise par une durée de finition longue (220 j), des génisses abattues plus lourdes (700 kg) et des ingestions faibles de CONC, d’UFL et de PDI. Cette classe se caractérise également par une finition au pâturage. La classe A_lourde (n=32) est caractérisée par des génisses abattues plus âgées (36,3 mois) et plus lourdes (726 kg). Une finition en bâtiment et une ration à base d’ensilage et/ou de paille caractérisent également cette pratique. Enfin, la classe Conc_leg (n=24) est caractérisée par des génisses abattues légères (661 kg) et ingérant des quantités élevées de CONC, d’UFL et de PDI. Les effets des différentes classes de pratiques sur les caractéristiques de la carcasse et les propriétés sensorielles de la bavette de flanchet ont été évalués par analyse de la variance. La pratique d’élevage de la classe A_lourde permet d’atteindre une qualité de carcasse plus élevée selon les critères de rémunération de l’éleveur (poids, conformation, état). La pratique de la classe J_leg permet une qualité sensorielle de la bavette plus élevée. Ces deux pratiques d’élevage assez antagonistes montrent qu’un pilotage conjoint de la qualité des carcasses et des viandes, chez la génisse de race Charolaise, s’avère difficile. Des compromis durant la phase de finition doivent donc être trouvés pour ne pas privilégier l’une de ces deux qualités

Prediction of beef carcass quality clusters from muscle biomarkers

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