Breast Myopathy Research Articles

Progressive in vivo detection of wooden breast in broilers as affected by dietary energy and protein

Wooden breast (WB) myopathy was investigated in broilers fed varying energy and protein at early ages. Correlation analyses were conducted between echogenicity of ultrasound images (US) of breast muscle from live birds and WB after slaughter. A total of 1,000 Cobb 500 one-day-old male chicks were fed on five dietary programs with eight replicates of 25 birds each, in a completely randomized design. Control feeds (commercially used ME and ideally balanced amino acids) or low-density feeds (low EP, with reductions of 50 kcal/kg ME and 0.20% dig. Lys compared to the control) were formulated. Feeds were provided in different periods: 1 to 7 d, 8 to 14 d, 15 to 21 d or 22 to 28 d. All broilers were fed a common basal diet thereafter until 49 d. Images using US were obtained once a week from all individuals and WB scored from one slaughtered bird per replication (0, normal; 1, mild hardening in the upper breast muscle; 2; moderate hardening in the upper and/or lower breast muscle; 3, severe hardening; 4, severe hardening with hemorrhagic lesions and yellow fluid). Blood was collected for enzyme investigation from the weekly slaughtered bird. Broilers had lower BWG and higher FCR when fed low EP feeds, regardless of the period fed when compared to the control (P < 0.001). Growth compensation, however, occurred afterwards such that all birds presented similar performance at the end. At 14, 21, and 28 d, broilers previously fed low EP feeds had lower WB scores (P < 0.001) compared to birds fed the control; however, both groups presented increased WB scores after 28 d. Wooden breast was positively correlated with breast echogenicity at 21 d (r = 0.31), 28 d (r = 0.43), 35 d (r = 0.21) and 42 d (r = 0.39). In conclusion, dietary energy and protein affected the development of WB scores in broilers and breast US images can be used as an early predictor of WB.

Physical, Chemical and Histological Characterization of Pectoralis major Muscle of Broilers Affected by Wooden Breast Myopathy.

Simple SummaryWooden breast myopathy is a muscle abnormality resulting from the genetic improvement practiced by the poultry industry and which is widespread throughout the planet. Recent research has tried to unravel this myopathy for years and how the quality of the meat is affected, in search of its etiology and the solution to this problem. Unfortunately, the problems related to the myopathies of the affected birds will only be solved when the cause of the abnormality is in fact unveiled and controlled; in the meantime, it is up to us researchers to contribute scientifically to research on this type of meat that is fit for consumption but that, for often presenting non-standard appearance for sale in the form of whole fillets, is discarded.This study aimed to characterize the effects of wooden breast myopathy (WBM) on quality of broiler chicken breast meat. Normal samples (absence of myopathy), moderate-degree samples (hardness only in one area of the breast fillet) and severe-degree samples (hardness throughout the breast fillet) were classified. In macroscopic analysis, the pectoral muscle affected by the WBM showed, in general, pale color with stiff, irregular and reddish regions (suffusions and petechiae), with the presence of white striations. In microscopic analysis, the myopathy was characterized by loss of the polygonal aspect of the muscle fibers. Samples with moderate degree of the myopathy showed greater (p = 0.0266) water retention capacity. There was an increase (p = 0.004) in total collagen concentration in samples from the severe-degree group 0.29% in normal samples to 0.43% and 0.48% in samples from moderate- and severe-degree groups, respectively. Samples of chicken breast affected by the severe-degree WBM showed lower (p < 0.0001) myofibrillar fragmentation index (64.51) and lower (p = 0.0002) fat concentration (2.17%) than normal chicken samples (80.45 and 3.79%, respectively). Samples affected by WBM are larger and heavier and present poorer physical quality when compared to normal chicken meat. Histologically it is possible to observe loss of the polygonal aspect of muscle fibers.

Effects of Storage on Quality Traits of Sausages Made with Chicken Breast Meat Affected by Wooden Breast

Simple SummaryStudies of the meat quality of modern birds and their respective myopathies are important to clarify the influence of these on the meat quality of the animals. The constant genetic evolution that birds have undergone is the most plausible cause for the onset of Wooden Breast Myopathy. The processing of byproducts, such as sausages, represents an alternative to avoid the losses that this myopathy generates to the poultry industry due to discards of chickens affected by different degrees of wooden breast myopathy. The aim of this study was to examine the effects of storage on the quality of sausages made with breast from chickens affected by wooden breast myopathy (WBM). Breast samples from male broilers slaughtered at 48 days old were used. Normal (absence of myopathy), moderate degree (hardness only in one region of the breast) and severe degree samples (hardness over the entire length of the breast) were processed into sausages and evaluated prior to storage and after being vacuum-packed and stored for 7, 14, 21 and 28 days at 4 °C. There was a decrease (p < 0.001) in pH and an increase (p < 0.001) in cooking weight loss in samples of sausages, regardless of the myopathy, after 28 days of storage. Sausages produced with chicken breast samples affected by wooden breast myopathy presented higher (p < 0.0001) moisture concentration (72% for the severe degree) and higher (p = 0.0224) protein concentration (17.27% and 17.36%, respectively, for the moderate and severe degrees) than sausages made of normal samples (70.72% and 14.32%, respectively). The results indicate that sausages produced with meat from birds moderately and severely affected by the myopathy show higher oxidative stability. Fresh sausages produced with breast meat from birds affected by wooden breast syndrome may be stored (4 °C) for up to 28 days without exhibiting the characteristic rancid taste and smell. In sensory analysis, no differences were observed between the formulations, which suggests that the consumers approved the samples regardless of the disease severity in the meat used for the making of the sausages. The current results show that chicken meat affected by wooden breast myopathy can be used for producing fresh sausages in the industry.

Effect of growth selection of broilers on breast muscle satellite cell function: Response of satellite cells to NOV, COMP, MYBP-C1, and CSRP3

The wooden breast (WB) myopathy is characterized by the palpation of a hard pectoralis major muscle that results in the necrosis and fibrosis of muscle fibers in fast-growing heavy weight meat-type broiler chickens. Necrosis of existing muscle fibers requires the repair and replacement of these myofibers. Satellite cells are responsible for the repair and regeneration of myofibers. To address how WB affects satellite cell function, top differentially expressed genes in unaffected and WB-affected pectoralis major muscle determined by RNA-Sequencing were studied by knocking down their expression by small interfering RNA in proliferating and differentiating commercial Ross 708 and Randombred (RBch) satellite cells. RBch satellite cells are from commercial 1995 broilers before WB appeared in broilers. Genes studied were: Nephroblastoma Overexpressed (NOV); Myosin Binding Protein-C (MYBP-C1); Cysteine-Rich Protein 3 (CSRP3); and Cartilage Oligomeric Matrix Protein (COMP). Ross 708 satellite cells had greatly reduced proliferation and differentiation compared to RBch satellite cells. MYBP-C1, CSRP3, and COMP reduced late proliferation and NOV did not affect proliferation in both lines. The timing of the knockdown differentially affected differentiation. If the expression was reduced at the beginning of proliferation, the effect on differentiation was greater than if the knockdown was at the beginning of differentiation. These data suggest, appropriate gene expression levels during proliferation greatly impact multinucleated myotube formation during differentiation. The effect of slow myofiber genes MYBP-C1 and CSRP3 on proliferation and differentiation suggests the presence of aerobic Type I satellite cells in the pectoralis major muscle which contains anaerobic Type IIb cells.

Effects of broiler genetic strain and dietary amino acid reduction on meat yield and quality (part II)

Genetic selection and advances in nutrition have improved broiler growth performance. However, meat quality issues have gained preference over increased growth rate. These meat quality issues may be reduced by lowering dietary amino acid (AA) content. In the present study, 5 common commercial broiler strains were fed either a control or an AA-reduced diet. The control diet was formulated to contain the highest digestible AA (lysine, total sulfur AA, and threonine) levels recommended for the 5 strains. The AA-reduced diet was formulated to contain 20% lower levels of these 3 digestible AA than in the control diet. This resulted in a 5 (strains) × 2 (AA levels) factorial arrangement. A total of 1,280 straight run broilers were randomly allocated to 8 replicate blocks. The AA reduction decreased absolute breast weights of 3 strains on day 42 and 2 strains on day 56, and decreased absolute weights of tender, wing, drumstick, and thigh on both day 42 and 56 for all 5 strains. However, the absolute fat pad weight and relative fat pad and thigh weights to BW were increased in the AA reduction treatments on both day 42 and 56. The AA reduction contributed to the lower breast meat pH on both day 42 and 56, which may have been directly related to decreased severe woody breast myopathy (WBM) incidence on day 42 and moderate WBM incidence on day 56. The severity of WBM was positively related to breast weight in all 10 treatments on both day 42 and 56, with the exception of birds in strain 3 on day 56 that were fed the AA-reduced diet. At the same time, AA reduction was more cost-effective when WBM incidence was considered in a theoretical model. In conclusion, WBM severity was associated with higher breast weight in birds of most strains fed either a control or AA-reduced diet. Dietary AA reduction decreased processing yields but decreased WBM incidence, which may be more economical.

Weighted gene co-expression network analysis identifies molecular pathways and hub genes involved in broiler White Striping and Wooden Breast myopathies

In recent years, the poultry industry has experienced an increased incidence of myopathies affecting breasts of fast-growing broilers, such as White Striping (WS) and Wooden Breast (WB) defects. To explore the molecular mechanisms and genes involved in WS and WB onset, we decided to perform a Weighted Gene Co-expression Network Analysis (WGCNA) using the gene expression profile and meat quality parameters of Pectoralis major muscles analysed in our previous study. Among the 212 modules identified by WGCNA, the red, darkred, midnightblue and paleturquoise4 modules were chosen for subsequent analysis. Functional analysis evidenced pathways involved in extracellular matrix (ECM) organization, collagen metabolism, cellular signaling and unfolded protein response. The hub gene analysis showed several genes coding for ECM components as the most interconnected nodes in the gene network (e.g. COL4A1, COL4A2, LAMA2, LAMA4, FBLN5 and FBN1). In this regard, this study suggests that alterations in ECM composition could somehow activate the cascade of biological reactions that result in the growth-related myopathies onset, and the involvement of Collagen IV alterations in activating the endoplasmic reticulum (ER) stress response may be hypothesized. Therefore, our findings provide further and innovative knowledge concerning the molecular mechanisms related to the breast abnormalities occurrence in modern broilers.

Broiler genetics influences proteome profiles of normal and woody breast muscle

Wooden or woody breast (WB) is a myopathy of the pectoralis major in fast-growing broilers that influences the quality of breast meat and causes an economic loss in the poultry industry. The objective of this study was to evaluate growth and proteome differences between 5 genetic strains of broilers that yield WB and normal breast (NB) meat. Eight-week-old broilers were evaluated for the WB myopathy and divided into NB and WB groups. Differential expression of proteins was analyzed using 2-dimensional gel electrophoresis and LC-MS/MS to elucidate the mechanism behind the breast myopathy because of the genetic backgrounds of the birds. The percentages of birds with WB were 61.3, 68.8, 46.9, 45.2, and 87.5% for strains 1-5, respectively, indicating variability in WB myopathy among broiler strains. Birds from strains 1, 3, and 5 in the WB group were heavier than those in the NB group (P < 0.05). Woody breast meat from all strains were heavier than NB meat (P < 0.05). Within WB, strain 5 had a greater breast yield than strains 1, 3, and 4 (P < 0.0001). Woody breast from strains 2, 3, 4, and 5 had a greater breast yield than NB (P < 0.05). Six proteins were more abundant in NB of strain 5 than those of strains 2, 3, and 4, and these proteins were related to muscle growth, regeneration, contraction, apoptosis, and oxidative stress. Within WB, 14 proteins were differentially expressed between strain 5 and other strains, suggesting high protein synthesis, weak structural integrity, intense contraction, and oxidative stress in strain 5 birds. The differences between WB from strain 3 and strains 1, 2, and 4 were mainly glycolytic. In conclusion, protein profiles of broiler breast differed because of both broiler genetics and the presence of WB myopathy.

Using air deformation of raw fillet surfaces to identify severity of woody breast myopathy in broiler fillets

This study was conducted to determine the effectiveness of air deformation on fillet surfaces to assess hardness and identify woody breast (WB) in raw fillets of broilers. Fillets (n = 120) were categorized in normal (NORM), mild (MILD) and severe (SEV) WB. All fillets were subjected to compression force (CF) analysis and pressurized air (344 kPa) was directed at the ventral surface of each fillet in the cranial region and the deformation area was measured. Fillets were cooked and sheared using Muellenet Owens Razor Shear (MORS) and blunt version of MORS (BMORS). CF increased as severity of WB increased (P < 0.05). Diameter of deformation area decreased (P < 0.05) as WB severity increased. CF was correlated to air deformation (rs = -0.43 to -0.66, P < 0.05). BMORS force and energy was higher (P < 0.05) in SEV fillets compared to those in MILD and NORM. SEV fillets had higher (P < 0.05) peak counts (PC) of shear curves using MORS or BMORS than MILD and NORM fillets (P < 0.05). The results indicate that WB can be identified by CF and that the use of air deformation in raw fillets which may be potentially utilized as a tool for WB assessment. Using BMORS paired with the peak counting method may be a better texture analysis method to access WB condition.

Detection of woody breast condition in commercial broiler carcasses using image analysis

Image analysis could be an objective and rapid method to identify woody breast (WB) myopathy and benefit the global poultry industry. The objective of this study was to determine if there are conformational changes that can be used to detect WB characteristics in commercial broiler carcasses across strains, gender, and ages using image analysis. A total of 900 images of male and female broiler carcasses from commercial standard and high breast-yielding strains and 5 ages (6 through 10 wk) were captured before evisceration. These images were processed and analyzed using ImageJ software. Conformational measurements were M0: breast length; M1: breast width in the cranial region; M2: vertical line from the tip of keel to 1/5th of breast length; M3: breast width at the end of M2; M4: angle formed at the tip of keel and extending to outer points of M3; M5: area of the triangle formed by M3 and lines generated by M4; M6: area of the breast above M3; M7: M6 minus M5. Ratios of these measurements were also considered. Intact breast fillets were scored for WB severity based on tactile evaluation. Regardless of strain, sex, and age, M11 (M1/M0), M9 (M3/M2), and M4 had the highest correlation to WB score (rs ≥ 0.65; P < 0.01). Overall, the best validated model (Gen. R2 = 0.61) to predict WB included M1, M2, and M3. Using this model, 91% of broiler carcasses were properly classified as normal or WB along with a sensitivity of 71% to detect affected carcasses. Although the predictive performance of models for detecting the WB condition using these measurements was associated with the broiler strain, sex, and age or live weight, these data also support the feasibility of using image analysis to predict WB defect in broiler carcasses. The possible integration of these image measurements into commercial noncontact, nondestructive, and fast in-line vision grading systems would allow processors to identify broilers with WB and potentially sort, provide large-scale information downstream to further processing operations and upstream to live production.

Upstream Regulator Analysis of Wooden Breast Myopathy Proteomics in Commercial Broilers and Comparison to Feed Efficiency Proteomics in Pedigree Male Broilers.

In an effort to understand the apparent trade-off between the continual push for growth performance and the recent emergence of muscle pathologies, shotgun proteomics was conducted on breast muscle obtained at ~8 weeks from commercial broilers with wooden breast (WB) myopathy and compared with that in pedigree male (PedM) broilers exhibiting high feed efficiency (FE). Comparison of the two proteomic datasets was facilitated using the overlay function of Ingenuity Pathway Analysis (IPA) (Qiagen, CA, USA). We focused on upstream regulator analysis and disease-function analysis that provides predictions of activation or inhibition of molecules based on (a) expression of downstream target molecules, (b) the IPA scientific citation database. Angiopoeitin 2 (ANGPT2) exhibited the highest predicted activation Z-score of all molecules in the WB dataset, suggesting that the proteomic landscape of WB myopathy would promote vascularization. Overlaying the FE proteomics data on the WB ANGPT2 upstream regulator network presented no commonality of protein expression and no prediction of ANGPT2 activation. Peroxisome proliferator coactivator 1 alpha (PGC1α) was predicted to be inhibited, suggesting that mitochondrial biogenesis was suppressed in WB. PGC1α was predicted to be activated in high FE pedigree male broilers. Whereas RICTOR (rapamycin independent companion of mammalian target of rapamycin) was predicted to be inhibited in both WB and FE datasets, the predictions were based on different downstream molecules. Other transcription factors predicted to be activated in WB muscle included epidermal growth factor (EGFR), X box binding protein (XBP1), transforming growth factor beta 1 (TGFB1) and nuclear factor (erythroid-derived 2)-like 2 (NFE2L2). Inhibitions of aryl hydrocarbon receptor (AHR), AHR nuclear translocator (ARNT) and estrogen related receptor gamma (ESRRG) were also predicted in the WB muscle. These findings indicate that there are considerable differences in upstream regulators based on downstream protein expression observed in WB myopathy and in high FE PedM broilers that may provide additional insight into the etiology of WB myopathy.

Evidence of vascular endothelial dysfunction in Wooden Breast disorder in chickens: Insights through gene expression analysis, ultra-structural evaluation and supervised machine learning methods.

Several gene expression studies have been previously conducted to characterize molecular basis of Wooden Breast myopathy in commercial broiler chickens. These studies have generally used a limited sample size and relied on a binary disease outcome (unaffected or affected by Wooden Breast), which are appropriate for an initial investigation. However, to identify biomarkers of disease severity and development, it is necessary to use a large number of samples with a varying degree of disease severity. Therefore, in this study, we assayed a relatively large number of samples (n = 96) harvested from the pectoralis major muscle of unaffected (U), partially affected (P) and markedly affected (A) chickens. Gene expression analysis was conducted using the nCounter MAX Analysis System and data were analyzed using four different supervised machine-learning methods, including support vector machines (SVM), random forests (RF), elastic net logistic regression (ENET) and Lasso logistic regression (LASSO). The SVM method achieved the highest prediction accuracy for both three-class (U, P and A) and two-class (U and P+A) classifications with 94% prediction accuracy for two-class classification and 85% for three-class classification. The results also identified biomarkers of Wooden Breast severity and development. Additionally, gene expression analysis and ultrastructural evaluations provided evidence of vascular endothelial cell dysfunction in the early pathogenesis of Wooden Breast.

Effect of vitamin E and alpha lipoic acid on intestinal development associated with wooden breast myopathy in broilers

Intestinal development is closely associated with inflammatory wooden breast (WB) myopathy. Vitamin E (VE) and alpha lipoic acid (ALA) with antioxidant and anti-inflammatory effects were used independently and in combination to evaluate their effects on intestinal developmental changes in ileal morphology and expression of genes related with gut nutrient transport, structure, and inflammation in broilers during the first 3 wk posthatch. A total of 160 newly hatched Ross 708 broiler chicks were randomly assigned into a control and 3 dietary treatments with 10 replicates of 4 birds each. Supplementation of VE (160 mg/kg) and ALA (500 mg/kg) independently and in combination were fed during the first 3 wk. At 1, 2, and 3 wk of age, one chick from each pen was harvested. Plasma VE concentration and ileal morphology were determined. Gene expression was measured by real-time quantitative PCR. Broilers in VE and combination of ALA and VE group had higher plasma VE concentration than the control and ALA group at 1, 2, and 3 wk of age (P < 0.01). All dietary treatments increased ileal villus height at 1 wk of age (P < 0.01) and decreased intraepithelial lymphocytes at 3 wk of age compared to the control (P ≤ 0.05). Combination of VE and ALA increased collagen type IV alpha 1 chain expression (P ≤ 0.05) and improved basement membrane structure indicating increased gut basement membrane integrity at 2 and 3 wk of age compared to the control. Expression of lipopolysaccharide-induced tumor necrosis factor-alpha factor associated with inflammation was decreased in all dietary treatments at 3 wk of age compared to the control (P < 0.01). Ileal morphology and gene expression were closely correlated with breast muscle morphology and gene expression. These results suggest that VE and ALA especially when they were combined in the diet had positive effects on mitigating intestinal inflammation and improving nutrient transport beginning at 1 wk of age, which is likely critical in reducing the severity of WB.

Day-old chicken quality and performance of broiler chickens from 3 different hatching systems

In on-farm hatching systems, eggs are transported at d 18 of incubation to the broiler farm, where chickens have immediate access to feed and water after hatching. In hatchery-fed systems, newly hatched chickens have immediate access to feed and water in the hatchery and are transported to the farm thereafter. Conventionally hatched chickens can remain without access to feed and water up to 72 h after hatching until placement on the farm. The current study compared day-old chicken quality, performance, and slaughter yield of broiler chickens that were on-farm hatched (OH), hatchery-fed (HF), or conventionally hatchery-hatched (HH). The experiment was performed in 6 rooms in 1 house. Each room contained 2 duplicate pens with approximately 1,155 chickens per pen; 2 rooms with each 2 duplicate pens were assigned to 1 treatment. The experiment was repeated during 3 consecutive production cycles. Chickens originated from young parent stock flocks. Results showed that HF and OH chickens were heavier and longer than HH chickens at day (D) 1. Relative weight of stomach and intestines were highest for OH chickens. The OH chickens had worse day-old chicken quality in terms of navel condition and red hocks than HH and HF chickens. Treatments did not differ in first wk and total mortality. From D0 until slaughter age, body weight was highest for OH, followed by HF and HH. Furthermore, carcass weight at slaughter age (D40) was highest for OH chickens, followed by HF and HH chickens. Breast fillets showed a higher incidence of white striping and wooden breast in HF and OH chickens compared with HH chickens. In conclusion, the current study showed that both OH and HF chickens of young parent flocks had better growth performance, which could explain the higher prevalence of breast myopathies, compared with HH. The worse day-old chicken quality for OH compared with HH and HF does not seem to affect first wk mortality and later life performance.

Texture and quality of chicken sausage formulated with woody breast meat

Woody breast (WB) myopathy is a quality defect, afflicting a large portion of commercial broilers to some degree. The WB myopathy is commonly attributed to rapid bird growth and characterized by excessive fibrosis within the pectoralis major, which is thought to cause the palpably hardened texture observed in the afflicted breast meat. These phenotypically tough breast fillets are not marketed for traditional intact muscle products owing to poor quality and eating experience. Potential avenues for these afflicted breast fillets include their use in formulation of fresh and cooked sausages. Two degrees of WB fillets (moderate and severe) were used as a replacement for normal (unafflicted) breast fillet meat at levels of 25, 50, and 100%, in a sausage formulation with 1.5% salt and 15% chicken fat. All 6 treatments were compared with a control formulation (100% normal breast meat) and analyzed for texture profile, cook loss, color, and proximate composition. Moisture and fat content for all formulations were similar (P = 0.95 and P = 0.33, respectively), but with increase in the inclusion rate of WB meat, lower protein content (P < 0.01) was observed. Raw sausage color indicated a lighter (P < 0.05) color for the control sausage (100% normal) than with both 100% moderate and 100% severe formulations. Similarly, sausages containing 100% severe WB meat were the darkest (L∗; P < 0.05), but they were similar to sausages containing 100% moderate (P > 0.05) WB meat. Texture profile analysis indicated a decrease in hardness, cohesiveness, and springiness with use of 100% severe WB meat, while inclusion of lower proportions of severe WB meat resulted in similar textural characteristics. These results indicate the possibility of using WB fillet meat in a sausage formulation with minimal impact on sausage texture profiles.

Physicochemical Properties and Consumer Acceptance of Hamburgers Processed with Chicken Meat Affected by Wooden Breast Myopathy.

Simple SummaryThe study of meat quality of modern birds and their respective myopathies is important to understand the influence of myopathy on the meat quality of these birds. The constant genetic evolution that birds have suffered and still suffer in the present is the most plausible cause of the onset of this myopathy. The processing of by-products, such as hamburgers, enters as an alternative to avoid losses that this myopathy generates in the poultry industry, with discards of chickens affected by the different degrees of myopathy in wooden breast.Considering the increased incidence of wooden breast myopathy in broilers, the intake involves no threat to human health, indefinite etiology consumer rejection by appearance in such breasts, and the lack of studies on the industrial use of wooden breast. The objective of this study was evaluating the quality of hamburgers made with chicken meat affected by wooden breast. Breast samples from broilers slaughtered at 48-days-old were used. Normal (absence of myopathy), moderate degree (hardness only in one region of the breast) and severe degree (hardness over the entire length of the breast) samples were processed for the manufacture of hamburgers whose quality analyses (color, pH, cooking weight loss, shrinkage percentage, tenderness, storage weight loss, water activity, lipid oxidation, chemical composition and consumer test) were performed on non-stored samples (Day 0), and after storing at 30, 60, 90 and 120 days at −20 °C. There was a reduction (p < 0.05) in tenderness in samples of moderate-grade hamburgers (from 161.45 N to 289.40 N) after 120 days of storage. Hamburgers produced with chicken breast samples affected by wooden breast myopathy presented higher (p < 0.0001) fat concentration (5.32 g/100 g and 5.26 g/100 g, respectively, for the moderate and severe degree) than hamburgers made of normal samples (4.45 g/100 g). Lipid oxidation values increased, which exceeded the limit of rancidity detection, independent of myopathy. The consumers equally appreciated the aroma, flavor, and texture, and rated their overall acceptance as similar regardless of the quality of chicken meat. Chicken breast hamburgers with wooden breast myopathy is a viable alternative for the poultry industry.

363 Meat Quality Matters: Trends and Mitigation Strategies for Muscle Myopathies in the Broiler Meat Industry

Abstract Broiler breast myopathies, including woody breast (WB), white striping (WS), and spaghetti breast (SB), negatively impact the industry. Broiler breast myopathy trends show that myopathies generally increase as the birds get older and larger, and they also increase as breast yield increases to higher levels. Gender can have some impact on myopathies, as males tend to have a higher frequency of WB and females have a higher frequency of SB. Mitigation strategies in both plant and live production are needed. In the short term, it is possible to sort carcasses/fillets manually in processing plants and technology is being developed to detect these issues automatically. These online methods may include image analysis of carcass/fillet shape or dimension features, or evaluating compression force to determine hardness. Fillets determined to be severe for these defects may be diverted into products such as comminuted ones, that are less impacted by appearance or reduced functionality relative to whole fillets. In live production, evaluating strategies to slow down growth rate overall (e.g. management or nutrition), or at strategic times, may be worth investigating, though this would be a short-term mitigation strategy. In the long term, strategies should focus on genetic programs. Breeder companies have always been committed in producing exceptional products. A multitude of methods for early detection of myopathies have tested over the years. Currently, innovative techniques centered around machine learning and more structured breeding programs have been leading the way in further improving meat quality without sacrificing yield. These and other intriguing approaches centralizing on the live bird will drive a positive trend in the quality and quantity of protein produced in the broiler industry.

367 Role of skeletal muscle satellite cells in the broiler chicken Wooden Breast myopathy

Abstract To meet the huge global demand for chicken meat, the commercial broiler industry has placed tremendous genetic selection pressure on breast meat yield, growth rate, and feed efficiency traits and has made remarkable improvements over the last 30 years. Unfortunately, along with those tremendous improvements has come a severe meat quality defect whose cause has yet to be elucidated. The Wooden (or Woody) Breast (WB) meat quality defect is characterized by visible bulging of the breast fillet with extreme hardness to the touch. The WB phenotype has been characterized by histopathologists as a degenerative myopathy in which excessive fibrotic tissue infiltration occurs. Skeletal muscle stem cells, also called satellite cells (MSC), play a critical role in post-hatch broiler skeletal muscle growth, repair, and maintenance. Yet the relationship between MSC function in high-yielding broilers and the development of the WB myopathy is still not well understood. Recent work using in vivo cell labeling, cryohistology, and immunofluorescence techniques demonstrates that the relative size and mitotic activity of the various MSC and macrophage populations and collagen deposition are altered in WB-affected muscle. Alterations in myogenic regulatory factor, collagen, and pro- and anti-inflammatory cytokine protein expression in WB-affected muscles have also been observed using quantitative fluorescent Western blotting. These data suggest the involvement of aberrant MSC function in the development of WB myopathy. Future work aimed at determining whether the apparent MSC dysfunction in WB-affected broilers is due to an issue with the MSC themselves and/or their environment will be accomplished using a combination of MSC isolation, labeling, transplant, and tracking strategies. Further exploration will also be required to understand how the local cell signaling mechanisms and cell population kinetics are related to the severity and timing of the development of the WB myopathy in today’s fast-growing, high-yielding broilers.

Enhanced transforming growth factor-beta signaling and fibrosis in the pectoralis major muscle of broiler chickens affected by wooden breast myopathy

Fibrosis has also been recorded as a prominent pathological feature within wooden breast (WB) myopathy of broiler chickens. This study was conducted to evaluate the accumulation of fibril collagen, deposition of the extracellular matrix (ECM) components, and the underlying mechanism mediating the pathogenic fibrotic process in the pectoralis major (PM) muscle of WB-affected birds. Broiler chickens were categorized into the control and WB groups based on the evaluation of myopathic lesions. Results indicated that the total content and area of collagen in cross-sections of the PM muscle, as well as the augmented expression of collagen-I and fibronectin in the ECM, were greatly increased in birds with WB. Wooden breast myopathy upregulated expressions of transforming growth factor-beta (TGF-β) and the phosphorylation of Smad 2 and 3, thereby activating TGF-β-mediated Smad signaling pathway, which further enhanced the transcription of profibrotic mediators. In addition, regulators involved in collagen biosynthesis and cross-linking including prolyl 4-hydroxylase, lysyl oxidase, lysyl hydroxylase, and decorin were increased in the WB muscle. Finally, the expressions of both matrix metalloproteinases (MMP) and tissue inhibitor of metalloproteinases (TIMP) were increased in the WB muscle, which might be related with reduced ECM remodeling. Overall, WB myopathy induces severe fibrosis by enhancing ECM deposition and collagen cross-linking in the PM muscle of broiler chickens, possibly via the activation of TGF-β signaling and the dysregulation of the MMP and TIMP system.

Effect of Pre-Blended Phosphates on the Freezing Quality Characteristics of Ground Woody Breast Meat Compared to Normal Meat.

Simple SummaryWoody breast (WB) myopathy is a major meat quality issue facing the global poultry industry. The WB affected meat can be ground, frozen, and utilized for further processed poultry products as needed. Freezing and thawing of WB meat may affect the functional properties of myofibrillar proteins such as lower water holding capacity and gelation. We found that pre-blended phosphate can increase the functionality of freshly ground WB meat and maintain it after freezing. We have demonstrated that the addition of phosphates can help the utilization of ground woody breast meat even after frozen storage.Woody breast (WB) myopathy affected meat has a tough texture, higher cook loss, and decreased water holding capacity (WHC), and thus lower consumer acceptability. The WB meat can be ground and further converted into further processed products or frozen, stored, and shipped to further processors. Freezing and thawing of ground WB meat may further affect the quality of WB meat products. Hence, research is required to determine the effect of pre-blended phosphates on the quality of ground WB meat as well as its cryoprotective effect during frozen storage. The objective of this experiment was to investigate the effect of pre-blended phosphate levels on meat quality in WB and normal breast (NB) fillets before and after freezing. NB fillets and severely affected WB fillets were procured from a local commercial processor. The meat was separated into various treatment groups according to the sodium tripolyphosphate (STPP) inclusion levels (0, 0.25, and 0.5% w/w). The meat was ground with respective phosphate treatments and subdivided into vacuum-sealed bags (n = 240; 1 kg each). Half of the bags (n = 120) from each treatment were taken for meat quality analysis, while the other bags were placed in a freezer (−18 °C) for 6 days. Fresh samples were analyzed within 6–8 h while the frozen samples were thawed for 18 h at 4°C prior to analysis. Samples (n = 10) were analyzed for gel strength, pH, color (L* a* b*), proximate composition, and randomly selected samples (n = 5) were analyzed for aerobic plate count (APC). Experiments were repeated in two separate replications and the data was analyzed using the Proc Glimmix model procedure in SAS (v. 9.4) (Cary, NC, USA) with LSMeans Separation at p ≤ 0.05. The gel strength (g) of the fresh ground NB meat (883.7 g) was higher than the gel strength of woody meat (720.8 g) with 0% phosphate (p ≤ 0.05). Addition of phosphate (0.25 and 0.5%) significantly increased the gel strength of fresh woody meat but it was significantly lower than NB meat added with 0.25 and 0.5% phosphate treatment. After freezing, ground NB meat samples with 0.25 and 0.5% phosphate had higher gel strength compared to fresh and frozen ground WB meat (p ≤ 0.05). Pre-blended STPP raised the pH in all treatments (p < 0.05). Treatments did not have any clear impact on APC of ground WB or NB meat. Addition of pre-blended sodium tripolyphosphate increases the functionality of fresh and frozen ground WB meat, as well as NB meat.

Wooden breast myopathy on broiler breast fillets affects quality and consumer preference.

The emergence of myopathies such as wooden breast in the poultry industry generally associated with the fast development of the breast muscle of broilers has provided changes in the morphological structure of muscle tissues, as well as problems of meat qualitative attributes. The aim of this study was to evaluate physical, chemical, qualitative, and sensorial attributes of broiler fillets associated with severity levels of wooden breast (WB) myopathy in a poultry slaughterhouse. Three hundred fillets in a poultry slaughterhouse were classified into three severity levels: normal (100 samples), moderate (100 samples), and severe (100 samples). After identification, classification, and description of changes, fillets with a severe WB level presented higher levels of red (a*), yellow (b*), and final pH. The lowest shear force and the highest myofibrillar fragmentation index were observed in fillets with a severe level when compared with normal fillets. The collagen content increased according to severity level. Tasters better evidenced the characteristic taste of chicken meat when tasting fillets with a severe WB level when compared with normal and moderate fillets. The succulence and preference of the Brazilian testers increased according to the severity level of the myopathy. In general, fillets with moderate and severe WB myopathy were affected not only in appearance but also in qualitative, physical, chemical, and sensory characteristics.