Characterization of muscle fiber type in the pectoralis major muscle of slow-growing local and commercial chicken strains

Integrative metabolomics and transcriptomics analysis revealed specific genes and metabolites affecting meat quality of chickens under different rearing systems

Different rearing systems have varying effect on animal welfare and meat quality of poultry. Currently, there are no established standards for the rearing systems of Chinese indigenous chickens. Our study aimed to investigate the effects of different rearing systems on the meat quality, gene profiles, and metabolites of Chinese indigenous chickens (Nanchuan chicken). 10-wk-old Nanchuan chickens (n=360) were randomly divided into 3 groups (cage, net, and free-range groups), with 6 replicates per group (20 chickens per replicate). The experiment lasted for 12 wk. At 154-days-old, 36 healthy chickens (6 males and 6 females per group) were randomly selected, euthanized, and their breast muscles were collected to assess the meat quality parameters and histomorphological characteristics. Additionally, breast muscles from 18 random hens (3 males and 3 females per group) were used for metabolomics and RNA-seq analysis. The results showed that rearing systems significantly affected the meat quality and myofiber characteristics. The meat quality of breast muscles from free-range chickens was superior to that of caged chickens, characterized by more tender meat and smaller myofiber cross-sectional areas. Integrative metabolomics and transcriptomics analysis revealed that the differentially expressed genes of chicken breast muscles were primarily involved in the myofiber differentiation. Mechanically, the improved meat quality of breast muscle in free-range chickens were mainly associated with enhanced skeletal muscle differentiation facilitated by fibromodulin, increased levels of up-regulated Acetyl-L-carnitine and Propionylcarnitine level, and decreased levels of Nonanoic acid and Elaidic acid abundance (Graphical abstract). This provides a comprehensive understanding of the most effective and sustainable breeding, production, and rearing systems for Chinese indigenous chickens. It also contributes to the current knowledge of the molecular mechanisms underlying the effects of rearing systems on growth performance and meat quality of chickens.

Research progress on regulating factors of muscle fiber heterogeneity in poultry: a review

Control of meat quality traits is an important goal of any farm animal production, including poultry. A better understanding of the biochemical properties of muscle fiber properties that drive muscle development and ultimately meat quality constitutes one of the major challenging topics in animal production and meat science. In this paper, the existing classification methods of skeletal muscle fibers in poultry were reviewed and the relationship between contractile and metabolic characteristics of muscle fibers and poultry meat quality was described. Finally, a comprehensive review of multiple potential factors affecting muscle fiber distribution and conversion is presented, including breed, sex, hormones, growth performance, diet, muscle position, exercise, and ambient temperature. We emphasize that knowledge of muscle fiber typing is essential to better understand how to control muscle characteristics throughout the life cycle of animals to better manage the final quality of poultry meat.

Research Progress on the Regulating Factors of Muscle Fiber Heterogeneity in Livestock: A Review

The type of muscle fiber plays a crucial role in the growth, development, and dynamic plasticity of animals' skeletal muscle. Additionally, it is a primary determinant of the quality of both fresh and processed meat. Therefore, understanding the regulatory factors that contribute to muscle fibers' heterogeneity is of paramount importance. Recent advances in sequencing and omics technologies have enabled comprehensive cross-verification of research on the factors affecting the types of muscle fiber across multiple levels, including the genome, transcriptome, proteome, and metabolome. These advancements have facilitated deeper exploration into the related biological questions. This review focused on the impact of individual characteristics, feeding patterns, and genetic regulation on the proportion and interconversion of different muscle fibers. The findings indicated that individual characteristics and feeding patterns significantly influence the type of muscle fiber, which can effectively enhance the type and distribution of muscle fibers in livestock. Furthermore, non-coding RNA, genes and signaling pathways between complicated regulatory mechanisms and interactions have a certain degree of impact on muscle fibers' heterogeneity. This, in turn, changes muscle fiber profile in living animals through genetic selection or environmental factors, and has the potential to modulate the quality of fresh meat. Collectively, we briefly reviewed the structure of skeletal muscle tissue and then attempted to review the inevitable connection between the quality of fresh meat and the type of muscle fiber, with particular attention to potential events involved in regulating muscle fibers' heterogeneity.

Unraveling the Genetic Foundations of Broiler Meat Quality: Advancements in Research and Their Impact

As societal progress elevates living standards, the focus on meat consumption has shifted from quantity to quality. In broiler production, optimizing meat quality has become paramount, prompting efforts to refine various meat attributes. Recent advancements in sequencing technologies have revealed the genome's complexity, surpassing previous conceptions. Through experimentation, numerous genetic elements have been linked to crucial meat quality traits in broiler chickens. This review synthesizes the current understanding of genetic determinants associated with meat quality attributes in broilers. Researchers have unveiled the pivotal insights detailed herein by employing diverse genomic methodologies such as QTL-based investigations, candidate gene studies, single-nucleotide polymorphism screening, genome-wide association studies, and RNA sequencing. These studies have identified numerous genes involved in broiler meat quality traits, including meat lightness (COL1A2 and ACAA2), meat yellowness (BCMO1 and GDPD5), fiber diameter (myostatin and LncIRS1), meat pH (PRDX4), tenderness (CAPN1), and intramuscular fat content (miR-24-3p and ANXA6). Consequently, a comprehensive exploration of these genetic elements is imperative to devise novel molecular markers and potential targets, promising to revolutionize strategies for enhancing broiler meat quality.

Lipid and Volatile Profiles of Various Goat Primal Cuts: Aspects of Nutritional Value and Flavor/Taste Attributes

The lipid and volatile profiles of goat primal cuts (shoulder, rib, loin, breast, and leg), as well as their potential impact on nutritional and flavor/taste attributes, were investigated. The breast cuts had the lowest protein but the highest fat content. Triacylglycerol was the predominant lipid in all cuts (82.22-88.01%), while the breast cuts had the lowest triacylglycerol and the highest diacylglycerol and free fatty acids. Also, the highest unsaturated fatty acid (UFA), both monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA), was obtained in the breast cuts. These findings correlated well with the highest peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) value. The volatile profiles of the various grilled cuts indicated that the breast and leg cuts had similar volatiles, with higher amounts of alcohol, aldehyde, ketone, and ester than others, which could explain the flavor oxidation by lipid and off-flavors in spoiled meat. While the shoulder, rib, and loin cuts had higher amounts of nitrogen-containing compounds. The highest sulfur-containing and hydrocarbon compounds were also observed in the shoulder cuts, which are mainly formed during the Maillard reaction and responsible for the cooked meat flavor. This investigation revealed that each cut of goat meat has a varied composition, especially in lipids and volatile compounds. Thus, meat quality differs in terms of nutritional aspects and flavor/taste characteristics, enabling consumers to select nutritious or proper cuts for their cooking to achieve the most satisfaction from goat meat consumption.

The hypoxia-inducible factor 1 pathway plays a critical role in the development of breast muscle myopathies in broiler chickens: a comprehensive review

In light of the increased worldwide demand for poultry meat, genetic selection efforts have intensified to produce broiler strains that grow at a higher rate, have greater breast meat yield (BMY), and convert feed to meat more efficiently. The increased selection pressure for these traits, BMY in particular, has produced multiple breast meat quality defects collectively known as breast muscle myopathies (BMM). Hypoxia has been proposed as one of the major mechanisms triggering the onset and occurrence of these myopathies. In this review, the relevant literature on the causes and consequences of hypoxia in broiler breast muscles is reviewed and discussed, with a special focus on the hypoxia-inducible factor 1 (HIF-1) pathway. Muscle fiber hypertrophy induced by selective breeding for greater BMY reduces the space available in the perimysium and endomysium for blood vessels and capillaries. The hypoxic state that results from the lack of circulation in muscle tissue activates the HIF-1 pathway. This pathway alters energy metabolism by promoting anaerobic glycolysis, suppressing the tricarboxylic acid cycle and damaging mitochondrial function. These changes lead to oxidative stress that further exacerbate the progression of BMM. In addition, activating the HIF-1 pathway promotes fatty acid synthesis, lipogenesis, and lipid accumulation in myopathic muscle tissue, and interacts with profibrotic growth factors leading to increased deposition of matrix proteins in muscle tissue. By promoting lipidosis and fibrosis, the HIF-1 pathway contributes to the development of the distinctive phenotypes of BMM, including white striations in white striping-affected muscles and the increased hardness of wooden breast-affected muscles.

Role of Clove and Tulsi on broiler health and meat production

The role of Clove (Cv) and Tulsi (Ts) supplementation on broiler growth performance and gut health as an alternative to antibiotic growth promoters has already been established. Therefore, the objectives of this study were to investigate the role of Cv and Ts on the serum biochemical profile and meat quality traits in broilers. A total of sixty (60) one-day-old commercial broiler chicks were randomly allotted into four homogenous groups (15 birds per group). They were then fed Cv powder and Ts extract from day (d) 8 to d 28 with drinking water i.e. zero level of Cv or Ts (T0), 0.5% Cv + 2% Ts (T1), 1.0% Cv + 3% Ts (T2), 1.5% Cv + 4% Ts (T3). Blood and meat samples were collected on d 14, 21, and 28 to analyze the serum-biochemical profile and meat quality. Supplementation of Cv and Ts improved serum-biochemical profile by reducing total cholesterol and low-density lipoprotein levels in broilers. However, they did not affect the serum protein levels while the 0.5-1% Cv and 2-3% Ts supplemented groups had higher glucose levels on d 21. Production of breast and thigh meat increased with increased size, and density of myofibers while fed 0.5-1% Cv and 2-3% Ts. On the contrary, 1.5% Cv powder and 4% Ts extract supplementation improved thigh meat color, breast and thigh meat pH as well as the water-holding capacity. The current study findings suggest that Cv and Ts can be used in combination to improve broiler health, production, and meat quality.

Higher Protein Digestibility of Chicken Thigh than Breast Muscle in an In Vitro Elderly Digestion Model

This study investigated the protein digestibility of chicken breast and thigh in an in vitro digestion model to determine the better protein sources for the elderly in terms of bioavailability. For this purpose, the biochemical traits of raw muscles and the structural properties of myofibrillar proteins were monitored. The thigh had higher pH, 10% trichloroacetic acid-soluble α-amino groups, and protein carbonyl content than the breast (p<0.05). In the proximate composition, the thigh had higher crude fat and lower crude protein content than the breast (p<0.05). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of myofibrillar proteins showed noticeable differences in the band intensities of tropomyosin α-chain and myosin light chain-3 between the thigh and breast. The intrinsic tryptophan fluorescence intensity of myosin was lower in the thigh than in the breast (p<0.05). Moreover, circular dichroism spectroscopy of myosin revealed that the thigh had higher α-helical and lower β-sheet structures than the breast (p<0.05). The cooked muscles were then chopped and digested in the elderly digestion model. The thigh had more α-amino groups than the breast after both gastric and gastrointestinal digestion (p<0.05). SDS-PAGE analysis of the gastric digesta showed that more bands remained in the digesta of the breast than that of the thigh. The content of proteins less than 3 kDa in the gastrointestinal digesta was also higher in the thigh than in the breast (p<0.05). These results reveal that chicken thigh with higher in vitro protein digestibility is a more appropriate protein source for the elderly than chicken breast.

Evaluation of dietary metabolizable energy concentrations on meat quality and lipid metabolism-related gene expression in yellow-feathered chickens

This study evaluated the effects of different dietary metabolizable energy (ME) concentrations on the meat quality, carcass traits, volatile flavour and lipid metabolism-related gene expression levels in yellow-feathered chickens. In total, 600 Huxu female chickens aged 90 days were randomly assigned to six dietary treatments, each with 10 replicates of 10 birds. During the finisher phase, the birds were fed diets containing 2880 (low), 2940, 3000, 3060, 3120 and 3180 (high) kcal ME/kg. The results showed that the average daily gain of chickens increased as the dietary ME concentration increased, while the feed to gain improved (p < 0.05), and the intramuscular fat content of breast muscle increased (p < 0.05). The energy concentration had no effect on the breast muscle pH (45 min and 24 h), colour parameter (L*) or percentage of drip loss (p > 0.05), but the shear force values decreased significantly (p < 0.05). The diameter and area of the breast muscle fiber decreased and the muscle fibre density increased as the dietary ME concentration increased (p < 0.05). The highest ME concentration (3180 kcal) increased the percentages of aldehydes (hexanal, heptanal, 2,4-nonadienal, octanal, nonanal and 2-decenal), alcohols (2-nonen-1-ol, trans-2-undecen-1-ol, 7-hexadecenal, 2-hexyl-1-decanoal and n-nonadecanol-1,3,7,11-trimethyl-1-dodecanol), alkanes (2,6-dimethyl-heptadecane) and carboxylic acids (9-hexadecenoic acid), but reduced the percentages of octadecanal, octadecane, heneicosane and tetradecanal (p < 0.05). In addition, the mRNA gene expression levels of fatty acid-binding protein 3 and apolipoprotein B were significantly upregulated in the liver, whereas that of cholesteryl ester transfer protein was significantly downregulated. In conclusion, increasing the ME diet to 3180 kcal/kg significantly improved the quality and flavour of the meat from yellow-feathered broilers. our finding may help poultry producers to improve the taste of meat by regulating genes related to lipid metabolism, thereby achieving the flavour and taste characteristics preferred by consumers.

Egg Quality of Italian Local Chicken Breeds: II. Composition and Predictive Ability of VIS-Near-InfraRed Spectroscopy

The aims of the present study were to characterize egg composition and develop VIS-Near-infrared spectroscopy (VIS-NIR) models for its predictions in Italian local chicken breeds, namely Padovana Camosciata, Padovana Dorata, Polverara Bianca, Polverara Nera, Pepoi, Ermellinata di Rovigo, Robusta Maculata and Robusta Lionata. Hens were reared in a single conservation center under the same environmental and management conditions. A total of 200 samples (25 samples per breed, two eggs/sample) were analyzed for the composition of albumen and yolk. Prediction models for these traits were developed on both fresh and freeze-dried samples. Eggs of Polverara Nera and Polverara Bianca differed from eggs of the other breeds (p < 0.05) in terms of the greatest moisture content (90.06 ± 1.23% and 89.57 ± 1.31%, respectively) and the lowest protein content (8.34 ± 1.27% and 8.81 ± 1.27%) in the albumen on wet basis. As regards the yolk, Robusta Maculata and Robusta Lionata differed (p < 0.05) from the other breeds, having lower protein content (15.62 ± 1.13% and 15.21 ± 0.63%, respectively) and greater lipid content (34.11 ± 1.12% and 35.30 ± 0.98%) on wet basis. Eggs of Pepoi had greater cholesterol content (1406.39 ± 82.34 mg/100 g) on wet basis compared with Padovana Camosciata, Polverara Bianca and Robusta Maculata (p < 0.05). Spectral data were collected in reflectance mode in the VIS-NIR range (400 to 2500 nm) using DS2500 (Foss, Hillerød, Denmark) on fresh and freeze-dried samples. Models were developed through partial least-squares regression on untreated and pre-treated spectra independently for yolk and albumen, and using several combinations of scattering corrections and mathematical treatments. The predictive ability of the models developed for each compound was evaluated through the coefficient of determination (R2cv), standard error of prediction (SEcv) and the ratio of performance to deviation (RPDcv) in cross-validation. Prediction models performed better for freeze-dried than fresh albumen and yolk. In particular, for the albumen the performance of models using freeze-dried eggs was excellent (R2cv ≥ 0.91), and for yolk it was suitable for the prediction of protein content and dry matter. Good performances of prediction were observed in yolk for dry matter (R2cv = 0.85), lipids and cholesterol (R2cv = 0.74). Overall, the results support the potential of infrared technology to predict the composition of eggs from local hens. Prediction models for proteins, dry matter and lipids of freeze-dried yolk could be used for labelling purposes to promote local breeds through the valorization of nutritional aspects.

Maternal immunization against myostatin suppresses post-hatch chicken growth

Myostatin (MSTN) is a negative regulator of skeletal muscle growth, thus it was hypothesized that immunization of hens against MSTN would enhance post-hatch growth and muscle mass via suppression of MSTN activity by anti-MSTN IgY in fertilized eggs. This study investigated the effects of immunization of hens against chicken MSTN (chMSTN) or a MSTN fragment (Myo2) on the growth and muscle mass of offspring. In Experiment 1, hens mixed with roosters were divided into two groups and hens in the Control and chMSTN groups were immunized with 0 and 0.5 mg of chMSTN, respectively. In Experiment 2, hens in the chMSTN group were divided into chMSTN and Myo2 groups while the Control group remained the same. The Control and chMSTN groups were immunized in the same way as Experiment 1. The Myo2 group was immunized against MSTN peptide fragment (Myo2) conjugated to KLH. Eggs collected from each group were incubated, and chicks were reared to examine growth and carcass parameters. ELISA showed the production of IgYs against chMSTN and Myo2 and the presence of these antibodies in egg yolk. IgY from the chMSTN and Myo2 groups showed binding affinity to chMSTN, Myo2, and commercial MSTN in Western blot analysis but did not show MSTN-inhibitory capacity in a reporter gene assay. In Experiment 1, no difference was observed in the body weight and carcass parameters of offspring between the Control and chMSTN groups. In Experiment 2, the body weight of chicks from the Myo2 group was significantly lower than that of the Control or chMSTN groups. The dressing percentage and breast muscle mass of the chMSTN and Myo2 groups were significantly lower than those of the Control group, and the breast muscle mass of Myo2 was significantly lower than that of the chMSTN. In summary, in contrast to our hypothesis, maternal immunization of hens did not increase but decreased the body weight and muscle mass of offspring.

Proteolysis and changes in meat quality of chicken pectoralis major and iliotibialis muscles in relation to muscle fiber type distribution

The proteolysis trends and meat quality of the chicken pectoralis major (PM) and iliotibialis (IL) muscles stored at 4°C for 7 d were investigated. After 7 d of storage, the purge loss was higher (P < 0.05) in PM than in IL muscle. The difference in the composition of muscle fibers between PM (100% fast type) and IL (88.85% fast and 11.15% slow types) resulted in differences in proteolysis. Fructose-bisphosphate aldolase, troponin I, myosin heavy chain, and malate dehydrogenase exhibited the same tendencies, but pyruvate kinase, creatine kinase, L-lactate dehydrogenase, and triosephosphate isomerase exhibited different tendencies in the 2 muscles. The activity of cathepsin B was higher in PM than in IL during storage (P < 0.05). These results indicate that the proteolysis trend and changes in meat quality during cold storage are dependent on the different muscle fiber characteristics.

Recurrent erosion of COA1/MITRAC15 exemplifies conditional gene dispensability in oxidative phosphorylation

Skeletal muscle fibers rely upon either oxidative phosphorylation or the glycolytic pathway with much less reliance on oxidative phosphorylation to achieve muscular contractions that power mechanical movements. Species with energy-intensive adaptive traits that require sudden bursts of energy have a greater dependency on glycolytic fibers. Glycolytic fibers have decreased reliance on OXPHOS and lower mitochondrial content compared to oxidative fibers. Hence, we hypothesized that gene loss might have occurred within the OXPHOS pathway in lineages that largely depend on glycolytic fibers. The protein encoded by the COA1/MITRAC15 gene with conserved orthologs found in budding yeast to humans promotes mitochondrial translation. We show that gene disrupting mutations have accumulated within the COA1 gene in the cheetah, several species of galliform birds, and rodents. The genomic region containing COA1 is a well-established evolutionary breakpoint region in mammals. Careful inspection of genome assemblies of closely related species of rodents and marsupials suggests two independent COA1 gene loss events co-occurring with chromosomal rearrangements. Besides recurrent gene loss events, we document changes in COA1 exon structure in primates and felids. The detailed evolutionary history presented in this study reveals the intricate link between skeletal muscle fiber composition and the occasional dispensability of the chaperone-like role of the COA1 gene.

Comparison of muscle fiber characteristics and glycolytic potential between slow- and fast-growing broilers

Muscle fiber characteristics had beneficial effects on meat masses and meat quality in broilers. Its number is determined at birth and directly affects the growth and development of muscle fibers after birth. However, whether the muscle fiber characteristics in different types of chickens are different at birth has not been fully documented. In this study, the 1-day-old Xueshan chicken (slow-growing broiler) and Ross 308 broiler (fast-growing broiler) were selected, respectively, and the fiber type distribution, fiber density, and fiber size in the breast (pectoralis major, PM) and leg (gastrocnemius, GAS) muscles were detected. The results showed that the PM only made up of type IIB fibers regardless of breed, and that few type I fibers (approximately 17.55%) was identified in GAS of Ross 308 broiler. The PM muscles had significantly higher fiber density, lower cross-sectional area and diameter than those of GAS muscles in both 2 breeds (P < 0.05). The highest fiber density was observed in PM of Xueshan chicken. Furthermore, the muscle fiber characteristics were partly controlled by glycolytic potential (GP), and the GP was also invesgated. The GP in PM and GAS of Ross 308 broiler were higher than in Xueshan chicken (P < 0.05). Taken together, 1-day-old Xueshan chicken exhibited higher fiber density and lower GP compared to 1-day-old Ross 308 broiler, especially in PM, which could not only reveal the differences of muscle characteristics among different types of chickens, but also explore a new way to improve the masses and quality of poultry meat.

Fiber characteristics and meat quality of different muscular tissues from slow- and fast-growing broilers

Chicken meat is an important source of high-quality animal protein. Its consumption continues to grow in both developed and developing countries. Muscle fiber characteristics are key determinants of meat quality and quantity. Skeletal muscle is a highly plastic tissue that is affected by breed differences and muscular tissues. However, studies regarding the effects of different breeds and muscular tissues on the fibers and meat quality traits in broilers are lacking. In this study, Ross 308 chickens (fast-growing [FG] broilers) and Xueshan chickens (slow-growing [SG] broilers) were selected, and their fiber and meat quality traits were characterized. The results showed that the breast muscle primarily comprised glycolytic fibers, whereas the leg muscle comprised glycolytic and a few oxidative fibers, regardless of the breed. The highest percentage of oxidative fibers (26.51%) appeared in the soleus muscle (SOL) of SG broilers. In addition, higher shear force, lower pressing loss, and thicker muscle fibers with less extracellular space were observed for SG meat than for FG meat. When comparing the different muscular tissues, a higher oxidative fiber percentage, ultimate pH, redness, and intramuscular fat (IMF) content were detected in the leg muscle than in the breast muscle in the 2 breeds. In summary, these data indicated that SG broilers had thicker muscle fibers than the FG broilers and that the leg muscle had more oxidative fibers than the breast muscle. Thicker fibers may contribute to increased firmness and more oxidative fibers lead to higher redness value and IMF content.

Effects of maternal dietary energy restriction on breast muscle fibre development in the offspring of broiler breeders

Objective

The effects of maternal dietary energy levels on breast muscle fibre development in offspring of broiler breeders were investigated.

Methods

A total of 480 20-week-old Arbor Acres (AA) healthy female broiler breeders, with an average body weight of 2.33±0.01 kg, were randomly divided into 4 treatment groups with 6 replicates and 20 broiler breeders for each replicate and fed a corn and soybean meal diet with 100%, 80%, 70%, and 50% energy levels, respectively. Approximately 300 eggs per treatment were collected for incubation for 6 days. Then, 120 0-day-old female broilers at each energy level were randomly selected and divided into 6 replicates with 20 broilers for each replicate, with this experimental phase with the offspring lasting for 49 days.

Results

Compared with the 100% energy group, the breast muscle fibre diameter at embryonic day 21 in the 80% energy group was significantly reduced (p<0.05). In the 80% energy group, the muscle fibre density of the breast increased significantly (p<0.05) at embryonic days 15 and 21. The breast muscle fibre diameter of the offspring in each group was significantly decreased (p<0.05) on the 1st day. The breast muscle sarcomere length of the embryos in the 80% energy group was significantly higher (p<0.05) than those in the 70% and 50% energy groups. Compared with the 100% energy group, the expression of the myostatin gene in the offspring was significantly decreased (p<0.05).

Conclusion

In conclusion, the effects of a maternal dietary energy level of 80% in this study were found to be optimal for breast muscle fibre development in offspring, which indicated that the metabolic energy level of AA broilers of 9.36 MJ/kg for the mid-term diet for laying eggs has a more practical significance.

Thai Native Chicken as a Potential Functional Meat Source Rich in Anserine, Anserine/Carnosine, and Antioxidant Substances

This study identified anserine and anserine/carnosine in chicken breast of Thai native chicken (TNC; 100% Thai native), Thai synthetic chicken (TSC; 50% Thai native), and Thai native crossbred chicken (TNC crossbred; 25% Thai native) compared with commercial broiler chicken (BR; 0% Thai native) using nuclear magnetic resonance (NMR) spectroscopy and the effect on antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl assay (DPPH). We conducted experiments with a completely randomized design and explored principal components analysis (PCA) and orthogonal projection to latent structure-discriminant analysis (OPLS-DA) to identify the distinguishing metabolites and relative concentrations from 1H NMR spectra among the groups. The relative concentrations and antioxidant properties among the groups were analyzed by analysis of variance (ANOVA) using the general linear model (GLM). This study revealed seven metabolites alanine, inositol monophosphate (IMP), inosine, and anserine/carnosine, lactate, anserine, and creatine. Lactate, anserine, and creatine were major components. In terms of PCA, the plots can distinguish BR from other groups. OPLS-DA revealed that anserine and anserine/carnosine in the chicken breast were significantly higher in TNC, TSC, and TNC crossbred than BR according to their relative concentrations and antioxidant properties (p < 0.01). Therefore, TNCs and their crossbreeds might have the potential to be functional meat sources.

Prospect of early vascular tone and satellite cell modulations on white striping muscle myopathy

Polyphasic myodegeneration potentially causes severe physiological and metabolic disorders in the breast muscle of fast-growing broiler chickens. To date, the etiology of recent muscle myopathies, such as the white striping (WS) phenotype, is still unknown. White striping–affected breast meats compromise the water holding capacity and predispose muscle to poor vascular tone, leading to the deterioration of meat qualities. Herein, this review article provides insight on the complexities around chicken breast myopathies: (i) the etiologies of WS occurrence in chicken; (ii) the metabolic changes that occur in WS defect in pectoralis major; and (iii) the interactions between breast muscle physiology and vascular tone. It also addressed the effects of nutritional supplements on muscle myopathies on chicken breast meats. Moreover, the review explored breast muscle biology focusing on the early preparation of satellite and vascular cells in fast-growth chicken breeds. Transcriptomics and histological analyses revealed poor vascularity in breast muscle of fast growth chickens. Thus, we suggest in ovo feeding of nutrients promoting vascularization and satellite cells replenishment as a potential strategy to enhance endothelium-derived nitric oxide availability to promote vascularization in the pectoralis major muscle region.

Positional Isomers of a Non-Nucleoside Substrate Differentially Affect Myosin Function

Molecular motors have evolved to transduce chemical energy from ATP into mechanical work to drive essential cellular processes, from muscle contraction to vesicular transport. Dysfunction of these motors is a root cause of many pathologies necessitating the need for intrinsic control over molecular motor function. Herein, we demonstrate that positional isomerism can be used as a simple and powerful tool to control the molecular motor of muscle, myosin. Using three isomers of a synthetic non-nucleoside triphosphate, we demonstrate that myosin's force- and motion-generating capacity can be dramatically altered at both the ensemble and single-molecule levels. By correlating our experimental results with computation, we show that each isomer exerts intrinsic control by affecting distinct steps in myosin's mechanochemical cycle. Our studies demonstrate that subtle variations in the structure of an abiotic energy source can be used to control the force and motility of myosin without altering myosin's structure.

Growth Performance Analysis of Two Italian Slow-Growing Chicken Breeds: Bianca di Saluzzo and Bionda Piemontese

Simple Summary

Bianca di Saluzzo and Bionda Piemontese are two Italian slow-growing chicken breeds of the Piemonte region (Northwest Italy) and are reared mainly for meat. They conserve adaptation to free ranging low input rearing systems and are promising for antibiotic-free farming. We aimed to analyze their growth using a mathematical model and to obtain some advice for improving performance. Polymorphism of the PAX7 gene was also studied to increase conservation value. The results confirmed that these breeds are late-maturing. Whereas selection would increase inbreeding, a mating scheme to bring inbreeding under control could be the most proper way to increase growth rate and reach commercial maturity earlier.

Abstract

Bianca di Saluzzo (BS) and Bionda Piemontese (BP) are two Italian chicken breeds, mainly reared for meat production, primarily in antibiotic-free farming. However, technical information on their growth pattern is still missing. At hatching, 150 unsexed chicks of each breed were weighed, labeled, and reared in indoor pens up to 8 w of age. At 8 w of age, the chicks were separated by sex and randomly transferred to growing pens with access to an external paddock (15 birds/pen; 4 pens/sex for each breed). The body weight (BW) was recorded biweekly for each bird, from hatching to 32 w of age. In order to identify an improvement strategy, the objectives of our study were to analyze the growth pattern of these birds using the Gompertz mathematical model and compare results with other chicken breeds. Polymorphism of the PAX7 gene was also analyzed to test its association with growth traits. Both BS and BP are close to unselected native breeds and, among the Italian local poultry, they are confirmed to be slow-growing birds with an intermediate size between heavy and light chicken breeds. Regarding the PAX7 gene, two alleles were found, F and G, and showed an association with the actual BW in the BP females from 14 w of age onwards. The G allele always exhibited a more favorable effect than the F allele. In small size poultry population, a delicate balance between preservation of biodiversity and performance improvement should be considered. Consequently, the most proper way could be an approach based on a mating scheme to keep inbreeding under control, increase growth rate, and improve commercial maturity.

Are Meat Quality Traits and Sensory Attributes in Favor of Slow-Growing Chickens?

The present study compared certain quality features and sensory attributes of the meat obtained from three different chicken genotypes: two endangered slow-growing indigenous breeds (Padovana: PAD, Polverara: POL) and a commercial broiler (Hybrid). Chickens (n = 42/genotype) were slaughtered at their commercial slaughter age: 183 days for PAD and POL chickens, and 35 days for the Hybrid. Breast and leg meat were dissected and used for qualitative evaluations. Results highlighted that genotype significantly affected final breast weight, with Hybrid showing higher values than both indigenous chickens. Conversely, PAD and POL meat was instrumentally tougher and richer in haem iron compared to the Hybrid. The sensory analysis conducted by a trained panel showed that the textural aspects and metallic flavor perception of PAD and POL meat differed from that of the Hybrid. These aspects were probably responsible for the lower overall acceptability of the PAD and POL meat compared to the Hybrid, as expressed by the consumer panel. A key step in making PAD and POL meat acceptable to consumers and stimulating its market seems thus the development of appropriate marketing strategies to transform product peculiarities in strength points.

Suitability of dual-purpose cockerels of 3 different genetic origins for fattening under free-range conditions

The utilization of male chickens for fattening constitutes a potential advantage of the dual-purpose concept. In addition to the use of commercial hybrids, producers could introduce alternative chicken genotypes or further develop local breeds. To gain more information about the genetic effect on growth performance, carcass characteristics, physicochemical meat traits, and sensory attributes, 60 cockerels belonging to Les Bleues (developed from the French breed Bresse Gauloise), Canarian (Spanish local breed), and Dominant Red Barred D459 (DRB D459; commercial dual-purpose hybrid) genotypes were reared under free-range conditions in a warm tropical climate and slaughtered at 15 wk of age. The major findings were as follows: (i) Les Bleues chickens exhibited the best growth rate and the body weight of 2.44 kg reached by this strain at 15 wk would be gained only after 18 to 19 wk with DRB D459 and it would take even 2 wk longer for Canarian breed, according to the growth modeling using the Morgan equation, although the body weights between the latter were statistical similar at 15 wk; (ii) Les Bleues strain had a good capability in terms of meat production performance, presenting carcasses with significantly heavier commercial cuts, and higher fleshiness than the other 2 genotypes; (iii) although significant differences among genotypes appeared in the physical characteristics of the breast meat, especially those concerning the skin and meat color and water-holding capacity, which was significantly reduced for Canarian chickens, no significant differences were detected in the chemical composition and fatty acid profile of the breast meat; (iv) trained panelists (n = 8) pointed out that leg meat of none of the genotypes is better in terms of global appreciation, but untrained consumers (n = 99) perceived that the Les Bleues leg meat was significantly more palatable than the DRB D459 leg meat.

Influence of free-range days on growth performance, carcass traits, meat quality, lymphoid organ indices, and blood biochemistry of Wannan Yellow chickens

This study investigated the effects of free-range days on growth performance, carcass traits, meat quality, lymphoid organ indices, and blood biochemical parameters of Wannan Yellow chickens. A total of 1,000 one-day-old male Wannan Yellow chickens were reared to 56 D. At 56 D of age, 960 birds with similar body weight (BW) were randomly allocated to free-range treatment at 56, 70, 84, and 98 D of age (assigned to free-range treatment for 42, 28, 14, and 0 D, respectively); 6 replicates with 40 chickens per treatment. In the free-range system, chickens were reared in indoor floor pens with an outdoor free-range paddock measuring 4 × 7 m (28 m2, 1.5 birds/m2). Results showed that BW of birds decreased significantly in the first 2 wk after birds were assigned to free-range treatment compared with those in the conventional treatment (P < 0.05). Average daily gain (ADG) and average daily feed intake (ADFI) decreased significantly (P < 0.05) for chickens assigned to free-range treatment from 56 to 70 D of age, while feed conversion ratio increased significantly (P < 0.05). Breast yield increased linearly with increasing free-range days (P < 0.05), whereas leg and foot yields decreased linearly (P < 0.05). Drip loss and L* value of thigh muscle decreased linearly with increasing free-range days (P < 0.05), while shear force improved linearly (P < 0.05). Additionally, the absolute thymus weight and thymus to BW ratio showed significant increasing and then decreasing quadratic responses to increasing free-range days (P < 0.05). Furthermore, serum glucose, total protein, cholesterol, and triglyceride content declined linearly, while high-density lipoprotein cholesterol (HDL-C) content increased linearly with increasing free-range days (P < 0.05). In conclusion, increasing free-range days had positive effects on breast yield, shear force, thymus weight, and HDL-C content, but negatively affected leg yield, foot yield, drip loss, L* value of thigh muscle, glucose, total protein, cholesterol, and triglyceride levels of Wannan Yellow chickens.

Effects of Slaughter Age on Muscle Characteristics and Meat Quality Traits of Da-Heng Meat Type Birds

Simple Summary

The current work evaluated the breast muscle performance, meat quality traits, and myofiber characteristics of Da-Heng meat type birds with 60, 90, 120, 150, 180 days of age. Older chickens often presented a higher pH, lower drip loss, higher shear force, darker, and redder breast meat. The correlation coefficients showed that myofiber characteristics played an important role in breast pH values, drip loss, and meat color.

Abstract

Due to the increasing demand for producing chickens with high meat quality, there is a need to determine its mode of action on chicken meat quality traits across a wider age spectrum. In this study, five groups of 200 male Da-Heng meat type birds were reared until slaughter age of 60, 90, 120, 150, 180 days old and breast muscle performance, meat quality traits, and myofiber characteristics were evaluated. The larger body weight and breast weight of chicken are based on larger myofiber diameter and area, less myofiber density for the older birds than younger birds. There was an age effect on all meat quality traits of chicken breast muscle (p < 0.05). Older chickens often presented a higher pH, lower drip loss, higher shear force, darker, and redder breast meat. The correlation coefficients showed that myofiber characteristics played an important role in breast pH values, drip loss, and meat color (p < 0.05). Besides, significant correlations were also found between meat quality traits (p < 0.05). Further studies are needed to explore the biochemical character and potential molecular mechanism of chicken breast muscle to determine the factors that causes these age-related differences in meat quality in the current study.

Dysregulation of lipid metabolism and appearance of slow myofiber-specific isoforms accompany the development of Wooden Breast myopathy in modern broiler chickens

Previous transcriptomic studies have hypothesized the occurrence of slow myofiber-phenotype, and dysregulation of lipid metabolism as being associated with the development of Wooden Breast (WB), a meat quality defect in commercial broiler chickens. To gain a deep understanding of the manifestation and implication of these two biological processes in health and disease states in chickens, cellular and global expression of specific genes related to the respective processes were examined in pectoralis major muscles of modern fast-growing and unselected slow-growing chickens. Using RNA in situ hybridization, lipoprotein lipase (LPL) was found to be expressed in endothelial cells of capillaries and small-caliber veins in chickens. RNA-seq analysis revealed upregulation of lipid-related genes in WB-affected chickens at week 3 and downregulation at week 7 of age. On the other hand, cellular localization of slow myofiber-type genes revealed their increased expression in mature myofibers of WB-affected chickens. Similarly, global expression of slow myofiber-type genes showed upregulation in affected chickens at both timepoints. To our knowledge, this is the first study to show the expression of LPL from the vascular endothelium in chickens. This study also confirms the existence of slow myofiber-phenotype and provides mechanistic insights into increased lipid uptake and metabolism in WB disease process.

Acidosis decreases the Ca2+ sensitivity of thin filaments by preventing the first actomyosin interaction

Intracellular acidosis is a putative agent of skeletal muscle fatigue, in part, because it depresses the calcium (Ca²⁺) sensitivity of the myofilaments. However, the molecular mechanism behind this depression in Ca²⁺ sensitivity is unknown, providing a significant challenge to a complete understanding of the fatigue process. To elucidate this mechanism, we directly determined the effect of acidosis on the ability of a single myosin molecule to bind to a regulated actin filament in a laser trap assay. Decreasing pH from 7.4 to 6.5 significantly (P < 0.05) reduced the frequency of single actomyosin-binding events at submaximal (pCa 8-pCa 6) but not at maximal Ca²⁺ concentration (pCa 5-pCa 4). To delineate whether this was due to a direct effect on myosin versus an indirect effect on the regulatory proteins troponin (Tn) and tropomyosin (Tm), binding frequency was also quantified in the absence of Tn and Tm. This revealed that acidosis did not significantly alter the frequency of actomyosin binding events in the absence of regulatory proteins (1.4 ± 0.15 vs. 1.4 ± 0.15 events/s for pH 7.4 and 6.5, respectively). Acidosis also did not significantly affect the size of myosin's powerstroke or the duration of binding events in the presence of regulatory proteins, at every [Ca²⁺]. These data suggest acidosis impedes activation of the thin filament by competitively inhibiting Ca²⁺ binding to TnC. This slows the rate at which myosin initially attaches to actin; therefore, less cross bridges will be bound and generating force at any given submaximal [Ca²⁺]. These data provide a molecular explanation for the acidosis-induced decrease in force observed at the submaximal Ca²⁺ concentrations that might contribute to the loss of force during muscle fatigue.

RNA-Seq Analysis Reveals Spatial and Sex Differences in Pectoralis Major Muscle of Broiler Chickens Contributing to Difference in Susceptibility to Wooden Breast Disease

Wooden Breast Disease (WBD) is a novel myopathy affecting the pectoralis major muscle of modern broiler chickens. The etiology of WBD is not currently known, but has been linked to increased feed efficiency, growth rate, and muscle yield in broiler chickens. Differential effect of WBD has been detected between regions of the P. major and between sexes of broilers-male birds and the cranial aspect of the muscle tend to be more severely affected by the disease than females and the caudal aspect. This study aimed to characterize biological differences in the P. major between regions of the muscle and sexes of birds. Samples were taken from the cranial and caudal aspects of P. major muscles of 3-week-old, unaffected male and female birds for RNA sequencing. RNA was extracted and used for preparation of cDNA libraries, which were sequenced by the Delaware Biotechnology Institute (DBI) using HiSeq2500. Sequence reads were aligned to the chicken reference genome with HISAT, and genes were analyzed for differential expression between regions of the breast muscle and sexes of birds using CuffDiff. Functional analysis was performed on differentially expressed genes (DEGs) between sex groups using DAVID and Ingenuity Pathway Analysis (IPA). There were 12 DEGs between cranial and caudal samples, and 260 between male and female birds. Out of the 260 genes differentially expressed between sexes, 189 were upregulated in males. Of this subset, 103 genes (55%) were located on the Z-chromosome. There was increased expression of genes involved in fat metabolism and oxidative stress responses in the cranial region of the P. major muscle, as well as increased expression of fat metabolism, oxidative stress response, antiangiogenesis, and connective tissue proliferation genes in male broilers. These results support the hypothesis that there are biological characteristics in male broilers and the cranial region of the breast muscle that may make them more susceptible to WBD, as well as raising the possibility of a metabolic switch in modern broiler chickens that may be more prominent in males.

Muscle characteristics in chicks challenged with Salmonella Enteritidis and the effect of preventive application of the probiotic Enterococcus faecium

The present study was conducted to assess the effects of the probiotic Enterococcus faecium AL41 (EF) and of the enteric pathogen Salmonella Enteritidis PT4 (SE) on the development of posthatch pectoralis major muscle (PM) of broiler chicks. The four experimental groups were control (CON), EF, SE, and EF+SE (EFSE). EF and SE were given per os from days 1 to 7 and at day 4 posthatch, respectively. Muscle samples from 6 chicks per group were taken at day 8 (D8) and day 11 (D11) to evaluate PM myofiber growth, capillarization, DNA, RNA, and protein content, as well as enzyme activities (isocitrate dehydrogenase, lactate dehydrogenase, creatine kinase). PM growth rate was 7.45 ± 2.7 g/d in non-SE groups (CON, EF) and 5.10 ± 1.82 g/d in SE-infected groups (P < 0.02). Compared with group CON, application of bacteria (groups EF and SE) reduced the fiber cross-sectional area (246 and 262 vs. 347 ± 19 μm2) and the number of myonuclei per fiber (0.66 and 0.64 vs. 0.79 ± 0.03). At D11, hypertrophic myofiber growth normalized in the EF group, but negative effects persisted in SE and EFSE birds contributing to lower daily PM gain. In addition, SE infection strongly disturbed PM capillarization. Negative effects on capillary cross-sectional area and on the area (%) covered by capillaries persisted until D11 in the SE group, whereas pre-feeding of EF restored capillarization in the EFSE group to control levels. We conclude that supplementation of the probiotic bacteria EF AL41 had positive effects on PM capillarization and, thus, on delivery of O2, supply of nutrients, and removal of metabolites. Supplementation of probiotic bacteria might therefore reduce energetic stress and improve muscle health and meat quality during SE infection.

Effects of caponization and age on the histology, lipid localization, and fiber diameter in muscles from Leghorn cockerels

Poultry researchers seek general and native lines of birds for capon production. The primary aim is to find high-quality meat with valuable sensory attributes. Castration decreases androgen levels and changes lipid metabolism, resulting in the accumulation of abdominal, subcutaneous, and intramuscular fat, which changes the flavor, texture, and tenderness of the meat. Histological analysis of selected skeletal muscles from Leghorn capons and cockerels was the main aim of the present study, along with examination of lipid localization in muscle tissue. We also assessed fiber type and diameter in the pectoral muscles (pectoralis major). The experiment was performed on 200 Leghorn cockerels; testes were removed at 8 wk of age. At 12, 16, 20, 24, and 28 wk of age, 6 cockerels and 6 capons were slaughtered, and samples from the pectoral and thigh muscles were evaluated. Differences in the focal necrosis of the fibers with infiltration of lymphoid cells (P < 0.05) were observed in thigh muscles, with higher numbers in cockerels than in capons. All examined locations in the pectoral and thigh muscles of capons (around the blood vessels, in the perimysium, in the endomysium, and in the sarcoplasm) showed higher concentrations of lipids compared to levels in cockerels. The analysis of fiber type in pectoralis major muscles revealed that all fibers were type IIB. The diameters of the fibers of the pectoral muscles were different (P < 0.05) at 28 wk of age, and the diameters of the giant fibers were different (P < 0.05) at 16 wk of age. The high concentration of lipids in the skeletal muscles of Leghorn capons is remarkable. Thus, ethical reasons as well as economic reasons should be considered when one-day-old cockerels are eliminated.

Effects of caponization and age on the histology, lipid localization, and fiber diameter in muscles from Greenleg Partridge cockerels

The preference of modern consumers for high-quality meat has forced breeders to use native breeds to produce capons. Caponization, both chemical and surgical, leads to androgen deficiency and changes in lipid metabolism and results in the accumulation of abdominal, subcutaneous, and intramuscular lipids, which change the sensory values of the meat. The aim of this study was to histologically evaluate selected skeletal muscles from Greenleg Partridge capons and cockerels. We examined lipid localization in the muscular tissue and also assessed both fiber type and fiber diameter in the pectoral muscles. The experiment was performed on 200 Greenleg Partridge cockerels and testes were removed at 8 wk of age. At 12, 16, 20, 24, and 28 wk of age, 6 cockerels and 6 capons were slaughtered, and samples from the pectoral and thigh muscles were evaluated. Our histopathological evaluation revealed only minimal changes, and no significant differences between capons and cockerels were observed. The pectoral and thigh muscles of the capons had higher concentrations of lipids around the blood vessels, in the perimysium, in the endomysium, and in the sarcoplasm. The analysis of fiber type in the Pectoralis major muscles revealed that the fibers were all the IIB type. The diameters of the fibers of the pectoral muscles were significantly different (P < 0.05) at 20, 24, and 28 wk of age, and diameters of the giant fibers were significantly different (P < 0.05) at 24 and 28 wk of age. High concentrations of lipids in the meat of the capons is undesirable due to health-related reasons. However, the ability of adipose tissue to improve the sensory values of meat will always be a major quality of native/traditional products.

Thai native chicken meat: an option to meet the demands for specific meat quality by certain groups of consumers; a review

Native chickens are slowly growing indigenous chicken (Gallus domesticus) breeds; many of them were developed from jungle fowl, which is found in every part of Asia. These breeds are disease resistant, easy adapting to tropical climates, and have a low mortality. In Thailand, a distinct sector of consumers prefers to eat meat from native chickens rather than that from broilers because it is more tasty and chewy. In addition, studies have shown that it has a low content of fat which may be helpful for people susceptible to coronary heart diseases. This review also compiles evidence for further indicators of a special meat quality such as more oxidative (Type I) muscle fibres, a higher collagen content (promoting the preferred chewiness), an elevated content of certain flavor-relevant compounds, as well as high ratio of polyunsaturated to saturated fatty acids.

Genetic parameters of white striping in relation to body weight, carcass composition, and meat quality traits in two broiler lines divergently selected for the ultimate pH of the pectoralis major muscle

BACKGROUND

White striping (WS) is an emerging quality defect with adverse consequences for the sensorial, technological, and nutritional qualities of breast meat in broiler chickens. The genetic determinism of this defect is little understood and thus the aim of the study presented here was to estimate the genetic parameters of WS in relation to other traits of economic importance such as body weight, carcass composition, and technological meat quality in an experimental population consisting of two divergent lines selected for high (pHu + line) or low (pHu- line) ultimate pH (pHu) of the pectoralis major (p. major) muscle.

RESULTS

The incidence of WS in the whole population was 50.7%, with 36.7% of broilers being moderately and 14% being severely affected. A higher incidence of moderate (p < 0.001) and severe (p < 0.0001) WS was observed in the pHu + line, and strong genetic determinism (h(2) = 0.65 ± 0.08) was evidenced for WS in the studied lines. In addition, WS was significantly genetically correlated with body weight (rg = 0.33 ± 0.15), and breast meat yield (0.68 ± 0.06), but not with the percentage of leg or abdominal fat. Increased body weight and breast muscle yield were significantly associated with increased incidence and severity of WS regardless of the line. Significant rg were observed between WS and several meat quality traits, including breast (0.21 ± 0.08) and thigh (0.31 ± 0.10) pHu, and breast cooking loss (0.30 ± 0.15). WS was also strongly genetically correlated with the intramuscular fat content of the pectoralis major muscle (0.64 ± 0.09), but not with the lipid oxidation index of this muscle.

CONCLUSIONS

This study highlighted the role of genetics as a major determinant of WS. The estimated genetic correlations showed that WS was more highly related to muscle development than to the overall growth of the body. The positive genetic association reported in this study between WS and muscle pHu indicated a possible relationship between the ability of muscle to store energy as a carbohydrate and its likelihood of developing WS. Finally, the strong genetic determinism of WS suggested that selection can be an efficient means of reducing the incidence of WS and of limiting its undesirable consequences on meat quality in broiler chickens.