Extending the Grazing Period for Bulls, Prior to Finishing on a Concentrate Ration: Composition, Collagen Structure and Organoleptic Characteristics of Beef.

peer-reviewedThe biochemical and organoleptic characteristics of the longissimus thoracis muscle from suckler bulls (n = 56) finished on a concentrate-based system (C) or raised in a pasture-based system (P) incorporating 99 (P99), 162 (P162) or 231 days (P231) of grazing prior to indoor finishing on the concentrate-based diet were investigated. Age at slaughter increased with increasing period at pasture. Intramuscular fat concentration was lower (p < 0.001) for P99 than for C, P162 and P231 bulls, which did not differ. Soluble collagen proportion was lower (p < 0.01) for P162 and P231 than for P99 and C bulls. Collagen cross-link content was higher (p < 0.05) for P231 than for P99 and C bulls and for P162 than for C bulls. The proportion of type I muscle fibres was higher (p < 0.01) for P231 and P162 than for P99 and C bulls. Sensory tenderness was higher (p < 0.001) for C and P162 than for P99 and P231 bulls and overall liking was higher (p < 0.01) for C than for P99 and P231 bulls but similar to P162 bulls. Extending the grazing period to 162 days did not negatively influence the sensory qualities of beef compared to the intensive concentrate-based system

What are the drivers of beef sensory quality using metadata of intramuscular connective tissue, fatty acids and muscle fiber characteristics?

peer-reviewedThe aim of this integrative study was to investigate the relationships between biochemical traits (total, insoluble and soluble collagens (TCol, ICol, SCol), cross-links (CLs), proteoglycans (TPGs), proportion of fiber types, total lipids (TLips), main fatty acids (FAs) families, the n-6/n-3 polyunsaturated FA (n-6/n-3PUFA) ratio and the sensory attributes scores (tenderness, juiciness, flavor) of two muscles from beef: Rectus abdominis (RA) and Longissimus thoracis (LT). For robust analysis, a database was prepared using samples from three studies from animals raised under different production systems. The analyses were performed either on each study separately or on pooled data per muscle after removing as many experimental effects as possible in each study. The CLs (across the muscles and studies) and, to a lower extent, type IIA muscle fibers (mainly for RA muscles), saturated FAs (SFAs), monounsaturated FAs (MUFAs) (for the LT muscles) were the components the most frequently associated with tenderness. The CLs, type IIA muscle fibers (mainly for the RA muscles), TLips, SFAs, MUFAs, conjugated linoleic acids (CLAs) and n-6/n-3 PUFA ratio (mainly for the LT muscles) were the components the most associated with juiciness. The TLips and CLAs (across the muscles and studies), SFAs, MUFAs (mainly for the LT muscles), CLs (mainly for the RA muscles) and TPGs (mainly for the LT muscles) were the components the most associated with flavor liking. The CLs, CLAs, TLips, SFAs, MUFAs, n-6/n-3 PUFA ratio, type IIA and I muscle fibers were the components the most frequently associated with the 3 sensory scores taken together. The SCol, TPGs and type IIX+B muscle fibers were little associated with the sensory scores taken together. The TCol, ICol and PUFAs were components the least associated with sensory scores. The data of this integrative study highlighted for the first time that the CLs were negatively involved in the determination of the three sensory traits mainly in the RA muscle. The muscle fibers in this integrative study had a weak impact on the variations in beef sensory traits. The type IIA and IIX+B muscle fibers were respectively negatively and positively associated with tenderness, negatively associated with juiciness and flavor. The type I muscle fibers were overall positively associated with juiciness and flavor and negatively or positively with tenderness and these associations were muscle and study-dependent. Overall, the TLips and FAs were positively associated with the sensory scores and the n-6/n-3 PUFA ratio was negatively associated with them.European Commissio

Propriétés structurales et biochimiques du tissu conjonctif intramusculaire et tendreté de la viande bovine

La perception de la viande bovine par le consommateur est un enjeu crucial pour l industrie de la viande. La tendreté reste l une des qualités organoleptiques essentielle aux yeux du consommateur, avec la jutosité et la flaveur. L objectif de ma thèse a été d étudier les propriétés structurales et biochimiques du tissu conjonctif intramusculaire responsables de la dureté de base et de faire le lien avec la tendreté et plus largement avec les qualités organoleptiques de la viande. Le développement et la mise au point d une méthode d analyse d images a permis d étudier objectivement les caractéristiques des composantes périmysiale et endomysiale du tissu conjonctif intramusculaire et de montrer que la surface occupée par ces deux structures influençait la tendreté de la viande. Préalablement à l étude biochimique et moléculaire du tissu conjonctif intramusculaire le dosage des protéoglycanes totaux a été développé et mis en place au laboratoire. Les résultats de cette deuxième partie ont permis de mettre en avant la complémentarité entre protéoglycanes, collagène total et liaisons de réticulation au sein du muscle et leur rôle sur la jutosité. Par ailleurs, nous avons pu mettre en évidence le rôle positif des protéoglycanes de haut poids moléculaire sur la jutosité, alors que les protéoglycanes de faible poids moléculaire, telle que la décorine,joueraient plutôt un rôle sur la dureté de la viande. L ensemble des résultats obtenus confirme nos hypothèses, à savoir que la composante structurale ainsi que les molécules minoritairement présentes dans le tissu conjonctif peuvent influencer les qualités organoleptiques de la viande bovine.The perception of beef by consumers is a crucial issue for the meat industry. Tenderness remains one of the sensory qualities essential to the consumer, with the juiciness and flavour. The aim of my thesis was to study the structural and biochemical properties of intramuscular connective tissue responsible for the background toughness and study relationships with tenderness and more widely with the sensory qualities of beef. The development of a method of image analysis was used to study objectively the characteristics of the perimysial and endomysial component of the intramuscular connective tissue. The results showed that the area occupied by these two structures influenced the beef tenderness. An assay for total proteoglycan measurement has been developed previously to the study of biochemical and molecular characteristics intramuscular connective tissue. The results obtained in this second part have highlighted the complementarities between proteoglycans, total collagen and cross-links within the muscle and their role on the juiciness. Furthermore, we were able to highlight the positive role of high molecular weight proteoglycans on juiciness, while low molecular weight proteoglycans, such as decorin, rather played a role in beef toughness. The overall results confirm our hypothesis that the structural components of the connective tissue and the small quantity of extracellular matrix molecules could influence the sensory qualities of beef.CLERMONT FD-Bib.électronique (631139902) / SudocSudocFranceF

Study of the Chronology of Expression of Ten Extracellular Matrix Molecules during the Myogenesis in Cattle to Better Understand Sensory Properties of Meat

The sensory properties of beef are known to depend on muscle fiber and intramuscular connective tissue composition (IMCT). IMCT is composed of collagens, proteoglycans and glycoproteins. The differentiation of muscle fibers has been extensively studied but there is scarcity in the data concerning IMCT differentiation. In order to be able to control muscle differentiation to improve beef quality, it is essential to understand the ontogenesis of IMCT molecules. Therefore, in this study, we investigated the chronology of appearance of 10 IMCT molecules in bovine Semitendinosus muscle using immunohistology technique at five key stages of myogenesis. Since 60 days post-conception (dpc), the whole molecules were present, but did not have their final location. It seems that they reach it at around 210 dpc. Then, the findings emphasized that since 210 dpc, the stage at which the differentiation of muscle fibers is almost complete, the differentiation of IMCT is almost completed. These data suggested that for the best controlling of the muscular differentiation to improve beef sensory quality, it would be necessary to intervene very early (before the IMCT constituents have acquired their definitive localization and the muscle fibers have finished differentiating), i.e., at the beginning of the first third of gestation

Classification of raw meat based on their sensory and mechanical features by multispectral images coupled with multi-layer feed-forward neural network trained with back-propagation algorithm

National audienc

Hierarchical mechanics of connective tissues: integrating insights from nano to macroscopic studies

As the key component of the musculoskeletal system, the extracellular matrix of soft connective tissues such as ligaments and tendons is a biological example of fibre-reinforced composite but with a complex hierarchical architecture. To establish a comprehensive structure-function relationship at the respective levels (i.e., from molecule to tissue) of the hierarchical architecture is challenging and requires a multidisciplinary approach, involving the integration of findings from the fields of molecular biology, biochemistry, structural biology, materials science and biophysics. Accordingly, in recent years, some of these fields, namely structural biology, aterials science and biophysics, have made significant progress in the microscale and nanoscale studies of extracellular matrix using new tools, such as icroelectromechanical systems, optical tweezers and atomic force microscopy, complemented by new techniques in simultaneous imaging and mechanical testing and computer modelling. The intent of this paper is to review the key findings on the mechanical response of extracellular matrix at the respective levels of the hierarchical architecture. The main focus is on the structure and function--the findings are compared across the different levels to provide insights that support the goal of establishing a comprehensive structure-function relationship of extracellular matrix. For this purpose, the review is divided into two parts. The first part explores the features of key structural units of extracellular matrix, namely tropocollagen molecule (the lowest level), microfibril, collagen fibril, collagen fibre and fascicle. The second part examines the mechanics of the structural units at the respective levels. Finally a framework for extracellular matrix mechanics is proposed to support the goal to establish a comprehensive structure-function relationship. The framework describes the integration of the mechanisms of reinforcement by the structural units at the respective levels of the hierarchical architecture in a consistent manner, both to allow comparison of these mechanisms and to make prediction of the interconnection of these mechanisms that can also assist in the identification of effective mechanical pathways. From a design perspective, this is a step in the direction towards the development of effective strategies for engineering materials to replace or repair damaged tissues, and for exogenous cross-linking therapy to enhance the mechanical properties of injured tissues

Contrôle hormonal des caractéristiques des fibres musculaires après la naissance

110 ref. 4 tables 4 graph.National audienceDuring postnatal development, the growth of skeletal muscle and the diversification of muscle fibre types are regulated by genetic, nutritional and endocrine factors. Herein, the crucial role played by several hormones will be reviewed with regard to their influence on fibre distribution and on myosin expression. Somatotropic hormones (GH and IGF-I) do not affect fibre composition but appear to regulate myosin isoform expression. Thyroid hormone increases the proportion of fast compared to slow fibres and the expression of fast myosin. Insulin influences fibre properties since a decrease in the fast IIB fibre percentage and a decrease in fast native isomyosins characterise insulinodependent diabete. Beta-adrenergic ago nists increase the proportion of IIB fibres. The extend to which they modify contractile properties has still to be characterised. Sex steroids differentially affect muscle fibres. Anabolic andro gens decrease the proportion of IIB fibres and the expression of IIb myosin heavy chain whereas estrogens do not influence fibre types. On the opposite, glucocorticoids induce muscle fibres atrophy and decrease the proportion of HB fibres. Their impact on myosin expression has received little attention. Increasing knowledge of how these hormones affect muscle fibres properties could have relievant applications in meat-producing farm animals.Après la naissance, la croissance et les propriétés contractiles et métaboliques des fibres musculaires sont soumises à une régulation endocrinienne complexe. A l’exception des glucocorticoïdes, la plupart des hormones présente une action anabolique sur le tissu musculaire. Leur influence sur les caractéristiques des fibres est cependant très différente. Ainsi, les hormones somatotropes affectent peu la composition en fibres des muscles. La GH, comme l’IGF-1, régulerait cependant l’expression des isoformes de myosine. Les hormones thyroïdiennes augmentent la proportion des fibres rapides au détriment des lentes. Elles régulent l’expression des chaînes lourdes de myosine, en augmentant celles des isoformes rapides. L’insuline joue également un rôle important, le diabète s’accompagnant d’une diminution du pourcentage relatif des fibres rapides glycolytiques et de la quantité des myosines natives rapides. Les agonistes béta-adrénergiques des catécholamines augmentent la proportion des fibres rapides IIB au détriment des lentes. Leur influence sur l’expression des myosines reste toutefois peu connue. L’action des stéroïdes sexuels est par contre bien documentée : les androgènes diminuent la proportion des fibres rapides IIB, et l’accumulation des chaînes lourdes de myosine IIb. Les oestrogènes ont peu d’effets reconnus sur ces caractéristiques. Enfin, si les fibres IIB constituent la principale cible des glucocorticoïdes, leur effet sur les caractéristiques des fibres est encore mal connu. L’ensemble de ces données suggère que l’on peut modifier la croissance du muscle et sa composition en fibres en modifiant l’équilibre endocrinien des animaux par les techniques d’élevage

Protéines de la matrice extracellulaire bovine et rôle potentiel dans la qualité de la viande : Premier recueil in silico Bos taurus

International audienceThe extracellular matrix (ECM) is a three-dimensional set of proteins that binds tissues and defines their biomechanical properties. Among the ECM components known to be involved in beef sensory qualities, authors have often studied fibrillar collagens but also, although less often, proteoglycans and some glycoproteins. The ECM contains many other proteins. Our hypothesis is that to deepen the role of ECM proteins in beef qualities and to identify new ones among the vast amount of data generated by high throughput methods, it is necessary to have a list of proteins of this matrix to refer to for the bovine species. We have therefore defined the Bos taurus matrisome known as the set of genes encoding ECM (core matrisome proteins and matrisome-associated proteins). We have used orthology, as a reference method, and a bioinformatic approach based on a computational pipeline previously published for Homo sapiens, Mus musculus and Danio rerio for the definition of their respective matrisome. We have reported here that the Bos taurus matrisome is composed of 1022 genes that we have classified according to the different matrisome categories. This list is the only matrisome of a livestock species to be defined to date. SIGNIFICANCE: In this study, we provide the first definition of matrisome of a livestock species, the Bos taurus. We believe that the Bos taurus matrisome will be of great interest for several reasons. It comes as a complement to the matrisomes of several other species such as Homo sapiens, Mus musculus, Danio rerio, Drosophila melanogaster and Caenorabditis elegans previously defined by other authors. It could be used to identify matrisome molecules among the vast amount of data generated by the high throughput methods. It thus can be used in addition to the other matrisomes as a model by the scientific community to study cell behavior and mechanotransduction and could lead to the identification of novel biomarkers for several diseases and cancers in which ECM is involved. Moreover, in the domain of studies on livestock, the dataset that we have provided here can be used in the context of product quality studies, especially meat quality, but also, for example, for lactation studies

La biologie musculaire et ses conséquences sur la qualité de la viande bovine

La biologie musculaire et ses conséquences sur la qualité de la viande bovin