Relationship among collagen amount, distribution and architecture in the M. longissimus thoracis and M. pectoralis profundus from pigs

Genome-wide association studies demonstrate the genes associated with perimysial thickness in ducks

The thickness of the perimysium has an essential effect on the tenderness of the meat. However, the genetic basis underlying perimysial thickness has not been determined. The objective of this study was to explore the quantitative trait loci (QTL) that influence perimysial thickness in an F₂ segregating population generated by Mallard × Pekin duck using the genome-wide association study (GWAS) method. Two QTL identified in chromosomes 27 and 13 displayed significant associations with perimysial thickness traits at the genome-wide level. The strongest association was the QTL located in chromosome 27, and this region had an effect on perimysial thickness and contained a promising candidate gene MAGI3 (Membrane-associated guanylate kinase, WW and PDZ domain containing 3). Meanwhile, association analysis showed that the top SNP within the MAGI3 gene was also associated with intramuscular fat content traits, which showed that perimysial thickness was positively correlated with intramuscular fat content. The second strongest association was the QTL region of chromosome 13. SUCLG2 (Succinate-CoA ligase GDP-forming subunit beta) is proximal to the top SNP and stood out as another candidate gene. Furthermore, the Transposase-Accessible Chromatin using Sequencing result showed that some key transcription factors (MYF5, MYOD1, KLF11) related to muscle development or energy metabolism might bind to the open regions of MAGI3 and SUCLG2. By analyzing the expression of different genotypes of the candidate gene, we speculate that different genotypes of MAGI3 may have an effect on breast muscle development, and then affect the thickness of the perimysium. This study maps two major genes of the duck breast muscle perimysial thickness trait, which helps to characterize muscle development and contributes to the genetic improvement of meat yield and quality in livestock.

Meta-analysis of the relationship between collagen characteristics and meat tenderness

Meta-analysis methods were used to investigate the effects of collagen content, solubility and pyridinoline cross-link content on Warner-Bratzler shear force (WBSF) and sensory tenderness in major meat species. Data was collected from the literature on pork, beef and lamb and analyzed independently for each species. The beef data was categorized into subgroups according to muscle (loin and other muscle) and age (young, <18 months and old, ≥18 months). The results showed that in beef, collagen content and pyridinoline cross-link content were positively correlated with WBSF and negatively with sensory tenderness, while collagen solubility was negatively correlated with WBSF. The correlation coefficients were greater in other beef muscles than loin. Significant correlations between collagen content and tenderness attributes were observed in old beef animals. However, non-significant relationships and large variations were found in pork and lamb. More studies with various muscles and ages are required for an in-depth understanding of the relationship between collagen characteristics and meat tenderness.

Comparison of Nutritional and Meat Quality Characteristics between Two Primal Cuts from Aceh Cattle in Aceh Province, Indonesia

The Aceh cattle are local Indonesian beef cattle that are farmed in Aceh Province. This type of cattle is one of the sources of meat for the Aceh people. This study aims to analyze the quality of two primal cuts (longissimus lumborum and semitendinosus muscle) from Aceh cattle based on the muscle microstructure characteristics and MSTN gene expression. This study used a sample of longissimus lumborum and semitendinosus muscles from 18 adult male Aceh cattle with the age of 2-2.5 years and a BCS of 3.24. Muscle samples were obtained shortly after the cattle were slaughtered in slaughterhouses in Banda Aceh and Aceh Besar districts. Muscle microstructure analysis was performed using the HE, Masson's trichrome, and immunohistochemistry staining methods, while the MSTN gene expression analysis was performed using the qPCR method. The analysis of the physical quality of meat includes pH, meat color, fat color, cooking loss, water holding capacity, and WBSF value. The results showed that the area of LL muscle fibers was smaller than that of ST with relatively the same diameter. Both muscles were dominated by fast fibers with a percentage of 82.37% (LL muscle) and 91.80% (ST muscle). The area and composition of the type of muscle fibers are the main factors that influence the tenderness of Aceh beef. A higher distribution of collagen was found in ST muscles than in LL muscles. MSTN gene expression in both muscle types was relatively the same. Aceh cattle have large muscle fibers and are dominated by fast fibers with a high percentage, resulting in a low level of the tenderness of Aceh beef. However, the level of tenderness of Aceh beef is still in accordance with the cooking preparation of original and favorite cuisine of Aceh people.

Concentration of collagen fibers in the musculature of broiler chickens fed with cupuacu seed by-product

ABSTRACT In this essay, we quantify the concentration of collagen fibers in broiler chickens exposed to increasing concentrations of cupuacu seed by-product. Collection of material was carried out in five chickens per treatment at 70 days old in the groups: control, 5% and 10% inclusion of cupuacu seed by-product. Fragments of Thoracic Pectoralis (PT) and Iliotibial lateralis (ITL) muscles were prepared for light and electronic microscopy. The amount of collagen fibers in the muscle groups was 1.08±0.61% in the PTC group; 6.24±2.58% in PT5% and 7.30±2.75% in PT10%. In the Iliotibial Lateralis groups, the results were 6.96±3.14% in the ITLC; 7.43±4.22% in the ITL5% and 8.66±2.35% in ITL10%. The amount of collagen fibers in the ITL5% and ITL10% groups showed no significant statistical difference. However, when compared to the ILTC group, there was a significant statistical difference. The PT muscle responds to standard nutritional changes, unlike the ILT muscle, which requires a high-nutrient formulation. The use of 5% cupuacu seed by-product has proven to be a viable alternative source of animal feed, as it promotes an increase in the concentrations of collagen fibers in the musculature of broiler chickens and is possibly the determining factor in meat texture.

Role of myofibers, perimysium and adipocytes in horse meat toughness

Horse meat is a good source of iron with low cholesterol but consumers consider tenderness most important when purchasing meat. Myofibers and intramuscular connective tissue, the main structural components of muscle, play major roles in meat toughness. The effects of myofibers and perimysium characteristics on Warner-Bratzler Shear Force (WBSF) values of horse semimembranosus were investigated on muscles previously assessed as tough (mean WBSF 68.87 ± 3.21 N, n = 8) or tender (mean WBSF 46.21 ± 2.27 N, n = 8). Mean Type IIA myofiber diameter was significantly greater in tender than in tough muscles. Secondary thick perimysium was thicker and collagen fibers more loosely arranged in tender muscles than in tough. A negative correlation was observed between WBSF values and perimysium thickness and a trend between WBSF and intramuscular fat. Adipocytes in perimysium of tender muscles may have contributed to thickening of perimysium and loosened collagen fibers thus contributing to tenderness of the meat.

Isolation and characterisation of collagen from elk antler velvet

Collagen was extracted from the antler velvet of elk (Cervus elaphus). Two types of collagen were prepared namely, acetic acid-soluble collagen and pepsin-soluble collagen. The electrophoretic patterns of both of the collagens showed that they were heterotrimeric, i.e. they consisted of α1α2α3. The total yield of the collagen obtained from the elk antler velvet was 12.1%. Amino acid analysis of the collagen by high-performance liquid chromatography showed that imino acid content such as that of proline and hydroxyproline was high, which might contribute to better visco-elastic properties. The peptide mapping of the collagens showed their similarity with porcine Type I collagen, thereby suggesting that the primary structure of both collagens is identical to that of porcine skin Type I collagen. The thermal denaturation temperature was 37°C, which is comparable to porcine Type I collagen and may also be as a result of high imino acid content.

Effect of myofiber characteristics and thickness of perimysium and endomysium on meat tenderness of chickens

The objective of the present study was to evaluate the role of myofiber characteristics and the thickness of 2 major muscle membranes, perimysium and endomysium, in determining the breast meat tenderness of chickens. Birds from 2 breeds (White Leghorn and a line of broiler) were chosen. Chicks were sexed and wing-banded at hatch and were grown in separate cages in a single house. Sixty broilers and 60 White Leghorns were harvested at 6 wk of age, respectively, whereas another 60 White Leghorns were slaughtered at 18 wk of age. An equal number of males and females was maintained for each group. Body weight, breast muscle weight, pH, drip loss, cooking loss, Warner-Bratzler shear force value (SFV), total energy of shear force, fiber diameter, sarcomere length, myofiber density, and the thickness of endomysium and perimysium of the breast were determined for each bird. At 6 wk of age, histological examination indicated that the size of myofiber and thickness of endomysium and perimysium of broilers were larger than that those of White Leghorns (P < 0.01), whereas the SFV, drip loss, and cooking loss of broilers were smaller (P < 0.01). A comparison between the White Leghorns at 18 wk and the broilers at 6 wk, which were at similar BW but different ages, showed that the breast muscle weight of broilers was larger (P < 0.01) than that of White Leghorns. For breast muscle, the endomysium of broilers at 6 wk was thicker than that of White Leghorns at 18 wk (P < 0.01), whereas the perimysium was thinner (P < 0.01). The SFV, drip loss, and the cooking loss of broilers were smaller than those of White Leghorns at similar BW (P < 0.01). Meat tenderness was negatively correlated with myofiber density (-0.27) and the thickness of endomysium (-0.29) and positively correlated with the thickness of perimysium (0.20). It is suggested that muscle membrane should be considered in evaluating meat tenderness of the chicken.

Histological contribution of collagen architecture to beef toughness

The relationship between shear-force value and collagen architecture of connective tissue of the longissimus thoracis (LT) muscle of Japanese Black (n = 10) and Brown (Kumamoto) (n = 5) steers (body weight: 688.4 +/- 8.6 kg as average and standard error) was investigated. There were negative correlations between the shear-force value and lipid content (n = 15, R(2)= 0.3709, P < 0.01) and protein content and lipid content (n = 15, R(2)= 0.6748, P < 0.01). Shear-force value and collagen content (n = 15, R(2)= 0.4344, P < 0.01) were positively correlated. In scanning electron microscopic photographs of the macerated preparation, the perimysium of the high-lipid LT muscle was broken down compared with the low-lipid LT muscle. The endomysium in all LT muscle fibers showed similar architecture. The fine surface cover of reticular collagen fibers around an adipocyte was observed in the high-lipid LT muscle perimysium. These results suggested that the shear-force value of the LT muscle was related to change in collagen architecture and of the perimysium in particular.

Collagen content and architecture of the Iliotibialis lateralis muscle in male chicks and broilers with different growth rates fed on different nutritional planes

1. Varying growth rates in chickens were induced by different nutritional regimes. The collagen content and architecture of iliotibialis lateralis (ITL) muscle were compared among 21-d-old chick types and broiler types at 80 or 95 d of age. 2. Relative size of ITL muscle was greater in the rapid growing (1.16% of live weight) than the slow growing chicks (1.02% of live weight). The 80-d-old broilers with a compensatory growth phase after an earlier slow growth period produced ITL muscle at 1.65-1.69% of live weight. The ITL muscle in 80- and 95-d-old broilers with restricted later growth after an earlier rapid growth period was 1.29 and 1.49% of live weight, respectively. 3. Collagen content of ITL muscle did not differ between chick types and also among the broiler types. However, collagen concentration decreased from 6.00-6.51 mg/g in the chicks to 3.33-4.00 mg/g in the broilers. 4. Thick and thin perimysia and honeycomb endomysia were viewed by scanning electron microscope (SEM) photography. In the perimysia, a central wide layer of longitudinal collagen fibres and peripheral narrow band of transverse fibres were distinguished. Collagen baskets of adipocytes were observed in the perimysia. 5. Perimysial collagen fibres markedly increased in number and formed a larger fibre cluster during growth from chicks to broilers. Endomysia changed from thin to thicker meshwork with growth. However, the collagen architecture of the muscle in broilers did not change under different nutritional regimes. 6. In conclusion, ITL muscle of chicken develops optimally when body growth is enhanced, but the collagen content and architecture in broilers are not affected by different growth processes.

Meat quality assessment using biophysical methods related to meat structure

This paper overviews the biophysical methods developed to gain access to meat structure information. The meat industry needs reliable meat quality information throughout the production process in order to guarantee high-quality meat products for consumers. Fast and non-invasive sensors will shortly be deployed, based on the development of biophysical methods for assessing meat structure. Reliable meat quality information (tenderness, flavour, juiciness, colour) can be provided by a number of different meat structure assessment either by means of mechanical (i.e., Warner-Bratzler shear force), optical (colour measurements, fluorescence) electrical probing or using ultrasonic measurements, electromagnetic waves, NMR, NIR, and so on. These measurements are often used to construct meat structure images that are fusioned and then processed via multi-image analysis, which needs appropriate processing methods. Quality traits related to mechanical properties are often better assessed by methods that take into account the natural anisotropy of meat due to its relatively linear myofibrillar structure. Biophysical methods of assessment can either measure meat component properties directly, or calculate them indirectly by using obvious correlations between one or several biophysical measurements and meat component properties. Taking these calculations and modelling the main relevant biophysical properties involved can help to improve our understanding of meat properties and thus of eating quality.

Towards developing standard operating procedures for pre-clinical testing in the mdx mouse model of Duchenne muscular dystrophy

This review discusses various issues to consider when developing standard operating procedures for pre-clinical studies in the mdx mouse model of Duchenne muscular dystrophy (DMD). The review describes and evaluates a wide range of techniques used to measure parameters of muscle pathology in mdx mice and identifies some basic techniques that might comprise standardised approaches for evaluation. While the central aim is to provide a basis for the development of standardised procedures to evaluate efficacy of a drug or a therapeutic strategy, a further aim is to gain insight into pathophysiological mechanisms in order to identify other therapeutic targets. The desired outcome is to enable easier and more rigorous comparison of pre-clinical data from different laboratories around the world, in order to accelerate identification of the best pre-clinical therapies in the mdx mouse that will fast-track translation into effective clinical treatments for DMD.