Differential expression and co-expression gene network analyses reveal molecular mechanisms and candidate biomarkers involved in breast muscle myopathies in chicken

The broiler industry is facing an increasing prevalence of breast myopathies, such as white striping (WS) and wooden breast (WB), and the precise aetiology of these occurrences remains poorly understood. To progress our understanding of the structural changes and molecular pathways involved in these myopathies, a transcriptomic analysis was performed using an 8 × 60 K Agilent chicken microarray and histological study. The study used pectoralis major muscles from three groups: slow-growing animals (n = 8), fast-growing animals visually free from defects (n = 8), or severely affected by both WS and WB (n = 8). In addition, a weighted correlation network analysis was performed to investigate the relationship between modules of co-expressed genes and histological traits. Functional analysis suggested that selection for fast growing and breast meat yield has progressively led to conditions favouring metabolic shifts towards alternative catabolic pathways to produce energy, leading to an adaptive response to oxidative stress and the first signs of inflammatory, regeneration and fibrosis processes. All these processes are intensified in muscles affected by severe myopathies, in which new mechanisms related to cellular defences and remodelling seem also activated. Furthermore, our study opens new perspectives for myopathy diagnosis by highlighting fine histological phenotypes and genes whose expression was strongly correlated with defects.

Quantum Blue Reduces the Severity of Woody Breast Myopathy via Modulation of Oxygen Homeostasis-Related Genes in Broiler Chickens

The incidence of woody breast (WB) is increasing on a global scale representing a significant welfare problem and economic burden to the poultry industry and for which there is no effective treatment due to its unknown etiology. In this study, using diffuse reflectance spectroscopy (DRS) coupled with iSTAT portable clinical analyzer, we provide evidence that the circulatory- and breast muscle-oxygen homeostasis is dysregulated [low oxygen and hemoglobin (HB) levels] in chickens with WB myopathy compared to healthy counterparts. Molecular analysis showed that blood HB subunit Mu (HBM), Zeta (HBZ), and hephaestin (HEPH) expression were significantly down regulated; however, the expression of the subunit rho of HB beta (HBBR) was upregulated in chicken with WB compared to healthy counterparts. The breast muscle HBBR, HBE, HBZ, and hypoxia-inducible factor prolyl hydroxylase 2 (PHD2) mRNA abundances were significantly down regulated in WB-affected compared to normal birds. The expression of HIF-1α at mRNA and protein levels was significantly induced in breasts of WB-affected compared to unaffected birds confirming a local hypoxic status. The phosphorylated levels of the upstream mediators AKT at Ser473 site, mTOR at Ser2481 site, and PI3K P85 at Tyr458 site, as well as their mRNA levels were significantly increased in breasts of WB-affected birds. In attempt to identify a nutritional strategy to reduce WB incidence, male broiler chicks (Cobb 500, n = 576) were randomly distributed into 48 floor pens and subjected to six treatments (12 birds/pen; 8 pens/treatment): a nutrient adequate control group (PC), the PC supplemented with 0.3% myo-inositol (PC + MI), a negative control (NC) deficient in available P and Ca by 0.15 and 0.16%, respectively, the NC fed with quantum blue (QB) at 500 (NC + 500 FTU), 1,000 (NC + 1,000 FTU), or 2,000 FTU/kg of feed (NC + 2,000 FTU). Although QB-enriched diets did not affect growth performances (FCR and FE), it did reduce the severity of WB by 5% compared to the PC diet. This effect is mediated by reversing the expression profile of oxygen homeostasis-related genes; i.e., significant down regulation of HBBR and upregulation of HBM, HBZ, and HEPH in blood, as well as a significant upregulation of HBA1, HBBR, HBE, HBZ, and PHD2 in breast muscle compared to the positive control.

Increased Expression of Lipid Metabolism Genes in Early Stages of Wooden Breast Links Myopathy of Broilers to Metabolic Syndrome in Humans

Wooden breast is a muscle disorder affecting modern commercial broiler chickens that causes a palpably firm pectoralis major muscle and severe reduction in meat quality. Most studies have focused on advanced stages of wooden breast apparent at market age, resulting in limited insights into the etiology and early pathogenesis of the myopathy. Therefore, the objective of this study was to identify early molecular signals in the wooden breast transcriptional cascade by performing gene expression analysis on the pectoralis major muscle of two-week-old birds that may later exhibit the wooden breast phenotype by market age at 7 weeks. Biopsy samples of the left pectoralis major muscle were collected from 101 birds at 14 days of age. Birds were subsequently raised to 7 weeks of age to allow sample selection based on the wooden breast phenotype at market age. RNA-sequencing was performed on 5 unaffected and 8 affected female chicken samples, selected based on wooden breast scores (0 to 4) assigned at necropsy where affected birds had scores of 2 or 3 (mildly or moderately affected) while unaffected birds had scores of 0 (no apparent gross lesions). Differential expression analysis identified 60 genes found to be significant at an FDR-adjusted p-value of 0.05. Of these, 26 were previously demonstrated to exhibit altered expression or genetic polymorphisms related to glucose tolerance or diabetes mellitus in mammals. Additionally, 9 genes have functions directly related to lipid metabolism and 11 genes are associated with adiposity traits such as intramuscular fat and body mass index. This study suggests that wooden breast disease is first and foremost a metabolic disorder characterized primarily by ectopic lipid accumulation in the pectoralis major.

Occurrence of Breast Meat Abnormalities and Foot Pad Dermatitis in Light-Size Broiler Chicken Hybrids

Only limited information regarding the occurrence of breast meat abnormalities and foot pad dermatitis (FPD) in current broiler genotypes is available. Therefore, this study was conducted to estimate the incidence and severity of breast myopathies (white striping, WS; wooden breast, WB; spaghetti meat, SM) and FPD in two fast-growing chicken hybrids, while simultaneously recording their growth performance. A total of 1560 one-day-old female chicks (780 for each hybrid, A and B; 12 replicates/genotype) were raised in the same environmental conditions and fed the same diet. Productive parameters were recorded at the end of each feeding phase. At slaughter (35 d), the occurrence of meat abnormalities and FPD was assessed on 150 breasts/genotype and on all of the processed birds, respectively. Although comparable growth performance was observed at slaughter, genotype B reported a significantly higher percentage of breasts without meat abnormalities (69% vs. 39%, 75% vs. 41%, 61% vs. 37% for WS, WB and SM, respectively) and also birds without FPD, than genotype A (53% vs. 23%, respectively). Overall, these findings highlight the importance of better understanding the effects of the genotype and the artificial selection applied to fast-growing chicken hybrids on the occurrence of emerging meat abnormalities and FPD even in light-size birds.

Effect of wooden breast condition on quality traits of emulsified chicken patties during frozen storage

Wooden breast (WB) is a recent abnormality characterized by tougher consistency in raw broiler breast fillets. This myopathy has been associated with negative alterations in chicken meat quality. The aim of this study was to evaluate the influence of WB condition on quality parameters of emulsified chicken patties (ECP) during frozen storage. Three formulations of ECP were processed, namely, PN (100% normal breast), PW (100% WB) and PNW (50%:50% normal:WB). ECP were frozen stored during 90 days and assessed by physicochemical and sensory analysis. Variations in redness were less pronounced in PW along the storage. TBARS were higher in PW and PNW until 30 days of storage compared to PN samples. Incorporation of WB into ECP formulation resulted in reduced peroxide-value, p-anisidine index and carbonyl content at the end of storage. Despite the different alterations in lipid and protein oxidation markers along storage time, results did not influence sensory acceptability, since no effect of wooden breast condition and storage time in odor and color liking was found in our experiment. This study elucidates for the first time that the use of WB meat for the elaboration of ECP is a feasible strategy to minimize economic losses for the poultry industry.

Effects of dietary Antrodia cinnamomea fermented product supplementation on metabolism pathways of antioxidant, inflammatory, and lipid metabolism pathways-a potential crosstalk

Objective

This study was conducted to fathom the underlying mechanisms of nutrition intervention and redox sensitive transcription factors regulated by Antrodia cinnamomea fermented product (FAC) dietary supplementation in broiler chickens.

Methods

Four hundreds d-old broilers (41±0.5 g/bird) assigned to 5 groups were examined after consuming control diet, or control diet replaced with 5% wheat bran (WB), 10% WB, 5% FAC, and 10% FAC. Liver mRNA expression of antioxidant, inflammatory and lipid metabolism pathways were analyzed. Prostaglandin E2 (PGE₂) concentration in each group were tested in the chicken peripheral blood mononuclear cells (cPBMCs) of 35-d old broilers to represent the stress level of the chickens. Furthermore, these cells were stimulated with 2,2′-Azobis(2-amidinopropane) dihydrochloride (AAPH) and lipopolysaccharide (LPS) to evaluate the cell stress tolerance by measuring cell viability and oxidative species.

Results

Heme oxygenase-1, glutathione S-transferase, glutamate-cysteine ligase, catalytic subunit, and superoxide dismutase, and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) that regulates the above antioxidant genes were all up-regulated significantly in FAC groups. Reactive oxygen species modulator protein 1 and NADPH oxygenase 1 were both rather down-regulated in 10% FAC group as comparison with two WB groups. Despite expressing higher level than control group, birds receiving diet containing FAC had significantly lower expression level in nuclear factor-kappa B (NF-κB) and other genes (inducible nitric oxide synthase, tumor necrosis factor-α, interleukin-1β, nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3, and cyclooxygenase 2) involving in inflammatory pathways. Additionally, except for 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase that showed relatively higher in both groups, the WB, lipoprotein lipase, Acetyl-CoA carboxylase, fatty acid synthase, fatty acid binding protein, fatty acid desaturase 2 and peroxisome proliferator-activated receptor alpha genes were expressed at higher levels in 10% FAC group. In support of above results, promoted Nrf2 and inhibited NF-κB nuclear translocation in chicken liver were found in FAC containing groups. H₂O₂ and NO levels induced by LPS and AAPH in cPBMCs were compromised in FAC containing diet. In 35-d-old birds, PGE₂ production in cPBMCs was also suppressed by the FAC diet.

Conclusion

FAC may promote Nrf2 antioxidant pathway and positively regulate lipid metabolism, both are potential inhibitor of NF-κB inflammatory pathway.

The metabolic characteristics of susceptibility to wooden breast disease in chickens with high feed efficiency

This study was conducted to characterize metabolic differences between high feed efficiency (HFE) and low feed efficiency (LFE) chickens to investigate why feed efficient chickens are more susceptible to muscle abnormalities such as wooden breast disease. Gene expression profiles were generated by RNA sequencing of pectoralis major muscle samples from 10 HFE and 13 LFE broiler chickens selected from a modern broiler population. Metabolism-associated differentially expressed genes were identified and interpreted by Ingenuity Pathway Analysis and literature mining. Our RNA-seq data indicate decreased glycolytic capacity, increased fatty acid uptake, mitochondrial oxidation of fatty acids, and several other metabolic alterations in the pectoralis major muscle of HFE chickens. We also quantified glycogen content of the pectoralis major muscle and found that the HFE chickens had a significantly (P ≤ 0.05) lower glycogen content. Collectively, this study indicates extensive metabolic differences in the pectoralis major muscle between HFE and LFE chickens and helps identify metabolic features of susceptibility to muscle disorders in modern broiler chickens.

Dietary potassium and available phosphorous on broiler growth performance, carcass characteristics, and wooden breast

Broiler dietary potassium (K) and available phosphorous (AvP) have decreased in recent years but both ions are intimately involved in the elimination of hydrogen ions that are produced during rapid growth. It was hypothesized that the decrease of these dietary electrolytes was related to the development of myopathies, and thus increased dietary K and/or AvP would reduce the occurrence of breast myopathies. A total of 320 Ross male broiler chicks were placed into 16 pens and fed 2 diet series containing either decreasing AvP levels of 0.45, 0.40, and 0.35% in the starter, grower, and finisher diets, respectively (Decline), or a fixed AvP of 0.45% in all dietary phases (Fixed). To complete a 2 × 2 design either normal basal dietary K (K-) (0.86, 0.77, 0.68%) or added dietary K (K+) (1.01, 0.93, 0.88%) were also applied to starter, grower, and finisher diets, respectively. Blood physiology was measured at 29 and 42 d. Carcass data, wooden breast and white striping scores were measured at 35 and 43 d. The K+ diets improved feed conversion ratio at 35 d (1.52 vs 1.57 g: g), reduced body weight at 42 d (3524 vs 3584 g), reduced hemoglobin (6.83 vs 7.58 g/dL), and packed cell volume (20.1 vs 22.3%) at 29 d, reduced ionized blood calcium (1.42 vs 1.47 mmol/L) at 42 d, and reduced partial pressure of blood CO2 (49.1 vs 54.7 mm/Hg) at 42 d relative to broilers fed basal K- diets (P < 0.05). Fixed AvP diets improved feed conversion ratio at 28 and 42 d, increased percentage breast meat (28.85 vs 27.58%) and carcass water pickup (2.72 vs 1.42%) at 35 d, and reduced wooden breast (2.88 vs 3.69) at 43 d (P < 0.05).

Effects of chlorogenic acid-enriched extract from Eucommia ulmoides leaf on performance, meat quality, oxidative stability, and fatty acid profile of meat in heat-stressed broilers

To investigate the effects of chlorogenic acid-enriched extract (CGAE) from Eucommia ulmoides leaf on performance, meat quality, oxidative stability, and fatty acid profile of breast meat in heat-stressed broilers, 400 28-day-old male Ross 308 broilers were randomly assigned into 4 groups with 10 replicates per group (10 broilers per replicate). Broilers in the normal group (NOR) were kept at 22 ± 2°C (24 h/D) and fed the basal diet, and the other 3 groups were treated with cyclic heat (34 ± 2°C from 08:00 to 18:00 and 22 ± 2°C from 18:00 to 08:00) and fed the basal diet supplemented with 0 (HT), 500 (CGAE500), and 1,000 mg (CGAE1000) mg of CGAE/kg of diet. The experiment lasted for 14 D. Compared with the HT group, broilers in the NOR and CGAE1000 groups had a higher average daily gain and a lower feed conversion ratio (P < 0.05). CGAE supplementation at 1,000 mg/kg increased pH24 value, a* value and total superoxide dismutase activity and reduced drip loss, cooking loss, L* value and the contents of malondialdehyde and carbonyl in breast meat of heat-stressed broilers (P < 0.05). Broilers in the HT group showed lower mRNA levels of nuclear factor erythroid 2-related factor 2 (P < 0.001), superoxide dismutase (P = 0.004), and catalase (P < 0.001) in breast meat compared with the other groups. CGAE supplementation at 1,000 mg/kg reduced the stearic acid and saturated fatty acids (SFA) contents and increased the dihomo-γ-linolenic acid, linoleic acid, linolenic acid, eicosapentaenoic acid, polyunsaturated fatty acids (PUFA), and n-6 PUFA contents and PUFA:SFA ratio in breast meat of heat-stressed broilers (P < 0.05). In conclusion, CGAE supplementation at 1,000 mg/kg could alleviate the adverse effects of heat stress on growth performance and meat quality and improve oxidative stability and fatty acid profile of breast meat in heat-stressed broilers.

Omega-3 and Omega-6 Fatty Acids in Poultry Nutrition: Effect on Production Performance and Health

Omega-3 (ω-3) and omega-6 (ω-6) fatty acids are important components of cell membranes. They are essential for health and normal physiological functioning of humans. Not all fatty acids can be produced endogenously owing to the absence of certain desaturases; however, they are required in a ratio that is not naturally achieved by the standard diet of industrialized nations. Poultry products have become the primary source of long-chain polyunsaturated fatty acids (LC-PUFA), with one of the most effective solutions being to increase the accretion of PUFAs in chicken products via the adjustment of fatty acids in poultry diets. Several studies have reported the favorable effects of ω-3 PUFA on bone strength, bone mineral content and density, and semen quality. However, other studies concluded negative effects of LC-PUFA on meat quality and palatability, and acceptability by consumers. The present review discussed the practical application of ω-3 and ω-6 fatty acids in poultry diets, and studied the critical effects of these fatty acids on productive performance, blood biochemistry, immunity, carcass traits, bone traits, egg and meat quality, and semen quality in poultry. Future studies are required to determine how poultry products can be produced with higher contents of PUFAs and favorable fatty acid composition, at low cost and without negative effects on palatability and quality.

Absolute expressions of hypoxia-inducible factor-1 alpha (HIF1A) transcript and the associated genes in chicken skeletal muscle with white striping and wooden breast myopathies

Development of white striping (WS) and wooden breast (WB) in broiler breast meat have been linked to hypoxia, but their etiologies are not fully understood. This study aimed at investigating absolute expression of hypoxia-inducible factor-1 alpha subunit (HIF1A) and genes involved in stress responses and muscle repair using a droplet digital polymerase chain reaction. Total RNA was isolated from pectoralis major collected from male 6-week-old medium (carcass weight ≤ 2.5 kg) and heavy (carcass weight > 2.5 kg) broilers. Samples were classified as “non-defective” (n = 4), “medium-WS” (n = 6), “heavy-WS” (n = 7) and “heavy-WS+WB” (n = 3) based on abnormality scores. The HIF1A transcript was up-regulated in all of the abnormal groups. Transcript abundances of genes encoding 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 4 (PFKFB4), lactate dehydrogenase-A (LDHA), and phosphorylase kinase beta subunit (PHKB) were increased in heavy-WS but decreased in heavy-WS+WB. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was up-regulated in non-defective samples. The muscle-specific mu-2 isoform of glutathione S-transferases (GSTM2) was up-regulated in the abnormal samples, particularly in the heavy groups. The genes encoding myogenic differentiation (MYOD1) and myosin light chain kinase (MYLK) exhibited similar expression pattern, of which medium-WS and heavy-WS significantly increased compared to non-defective whereas expression in heavy-WS+WB was not different from either non-defective or WS-affected group. The greatest and the lowest levels of calpain-3 (CAPN3) and delta-sarcoglycan (SCGD) were observed in heavy-WS and heavy-WS+WB, respectively. Based on micrographs, the abnormal muscles primarily comprised fibers with cross-sectional areas ranging from 2,000 to 3,000 μm². Despite induced glycolysis at the transcriptional level, lower stored glycogen in the abnormal muscles corresponded with the reduced lactate and higher pH within their meats. The findings support hypoxia within the abnormal breasts, potentially associated with oversized muscle fibers. Between WS and WB, divergent glucose metabolism, cellular detoxification and myoregeneration at the transcriptional level could be anticipated.

Effects of stale maize on growth performance, immunity, intestinal morphology and antioxidant capacity in broilers

OBJECTIVE

This study was conducted to determine the effects of stale maize on growth performance, immunity, intestinal morphology, and antioxidant capacity in broilers.

METHODS

A total of 800 one-day-old male Arbor Acres broilers (45.4±0.5 g) were blocked based on body weight, and then allocated randomly to 2 treatments with 20 cages per treatment and 20 broilers per cage in this 6-week experiment. Dietary treatments included a basal diet and diets with 100% of control maize replaced by stale maize.

RESULTS

The content of fat acidity value was higher (p<0.05) while the starch, activities of catalase and peroxidase were lower (p<0.05) than the control maize. Feeding stale maize diets reduced (p<0.05) average daily feed intake (ADFI) throughout the experiment, feed conversion ratio (FCR) during d 0 to 21 and the whole experiment as well as relative weight of liver, spleen, bursa of Fabricius and thymus (p<0.05) on d 21. Feeding stale maize diets decreased jejunum villus height (VH) and VH/crypt depth (CD) (p<0.05) on d 21 and 42 as well as ileum VH/CD on d 42. The levels of immunoglobulin G, acid α-naphthylacetate esterase positive ratios and lymphocyte proliferation on d 21 and 42 as well as lysozyme activity and avian influenza antibody H5N1 titer on d 21 decreased (p<0.05) by the stale maize. Feeding stale maize diets reduced (p<0.05) serum interferon-γ, tumor necrosis factor-α, interleukin-2 on d 21 and interleukin-6 on d 21 and 42. Broilers fed stale maize diets had lower levels of (p<0.05) total antioxidative capacity on d 42, superoxide dismutase and glutathione peroxidase on d 21 and 42, but higher (p<0.05) levels of malondialdehyde on d 21 and 42.

CONCLUSION

Feeding 100% stale maize decreased ADFI and FCR, caused adverse effects on immunity and antioxidant function and altered intestinal morphology in broilers.

Incidence of White Striping and Its Effect on the Quality Traits of Raw and Processed Turkey Breast Meat

The aim of this study is to evaluate the incidence of white striping abnormality and its consequences on the quality traits of raw and processed turkey breast (chemical composition, color traits, and water holding capacity). In total, about 2300 breasts from 22 flocks were used to assess the incidence and 60 breasts to evaluate the quality traits. Our study showed that the total incidence of moderate and severe white striping was 61.3% out of them, moderate cases were 49.4%. Severe white striped turkey breast exhibited significantly lower protein content (21.1 vs. 23.2 and 23.16%, p<0.05) and higher fat content (2.3 vs. 0.77 and 1.76%, p<0.05) if compared to normal and moderate white striped breast respectively. Moreover, moderate and severe white striped meat showed significantly higher redness (a*) (2.98 and 3.14 vs. 1.48, p<0.05) and yellowness (b*) indexes (7.27 and 7.95 vs. 4.05, p<0.05) than normal meat, respectively.

Fibrillar Collagen Organization Associated with Broiler Wooden Breast Fibrotic Myopathy

Wooden breast (WB) is a fibrotic myopathy affecting the pectoralis major (p. major) muscle in fast-growing commercial broiler lines. Birds with WB are phenotypically detected by the palpation of a hard p. major muscle. A primary feature of WB is the fibrosis of muscle with the replacement of muscle fibers with extracellular matrix proteins, such as collagen. The ability of a tissue to be pliable and stretch is associated with the organization of collagen fibrils in the connective tissue areas surrounding muscle fiber bundles (perimysium) and around individual muscle fibers (endomysium). The objective of this study was to compare the structure and organization of fibrillar collagen by using transmission electron microscopy in two fast-growing broiler lines (Lines A and B) with incidence of WB to a slower growing broiler Line C with no phenotypically detectable WB. In Line A, the collagen fibrils were tightly packed in a parallel organization, whereas in Line B, the collagen fibrils were randomly aligned. Tightly packed collagen fibrils arranged in parallel are associated with nonpliable collagen that is highly cross-linked. This will lead to a phenotypically hard p. major muscle. In Line C, the fibrillar collagen was sparse in its distribution. Furthermore, the average collagen fibril diameter and banding D-period length were altered in Line A p. major muscles affected with WB. Taken together, these data are suggestive of different fibrotic myopathies beyond just what is classified as WB in fast-growing broiler lines.

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.

Effect of breast myopathies on quality and microbial shelf life of broiler meat

To evaluate the impact of emerging myopathies on meat quality and microbial shelf life, 48 normal, 48 white striped (WS), and 48 wooden breasts (WB) were stored for 11 d at 4°C aerobically and analyzed at 24, 72, 120, 168, 216, and 264 h post-mortem. Normal breasts showed lower (P < 0.001) redness index (-0.88 vs. -0.41 and -0.43) and cooking losses (22.0 vs. 23.8 vs. 26.9%) than those of WS and WB meat. Normal and WS breasts exhibited higher protein content than that in WB meat (23.9 and 23.2 vs. 21.4%; P < 0.001). Normal meat also had a lower ether extract content than that in WB meat (1.09 vs. 1.88%; P < 0.001), with intermediate values for WS meat. Normal breasts exhibited higher saturated fatty acid (FA) rate (31.3 vs. 28.0% of total FA on average) and lower unsaturated FA rate (68.7 vs. 72.0%) than those in WS and WB meat (P < 0.001). Differences were mainly due to polyunsaturated FA (30.5% in normal vs. 35.3 and 35.4% in WS and WB meat; P < 0.001). Normal breasts had higher initial total viable count (TVC) and a shorter TVC lag phase than those of WS and WB meat (46.3 vs. 85.2 and 77.8 h). The microbial shelf life threshold (7 log10 CFU TVC/g) was achieved first in normal (130 h) and then in WS (149 h) and WB (192 h) meat. TVC and Pseudomonas spp. counts were significantly higher in normal than those in the affected breasts between 72 and 216 h of storage. Enterobacteriaceae spp. and lactic acid bacteria counts were significantly higher in normal meat, lower in WB meat, and intermediate in WS meat until 216 h. All differences in microbial targets across meat types disappeared by 264 h of storage. Further studies are necessary to elucidate the factors and the mechanisms that may modulate microbial growth and composition during storage in broiler breast meat affected by myopathies.

The effect of polyphenols and vitamin E on the antioxidant status and meat quality of broiler chickens fed low-quality oil

The aim of this study was to determine the effect of vitamin E and polyphenols on the antioxidant potential and meat quality of broiler chickens fed diets supplemented with low-quality oil. The experimental materials comprised 120 male Ross 308 broilers (six treatments, 10 replications, two birds per replication). Dietary supplementation with vitamin E and/or polyphenols was applied in the following experimental design: group I (negative control) – without supplementation without low-quality oil; group II (positive control) – without supplementation + low-quality oil; group III – supplementation with 100 mg kg-1 of vitamin E+ low-quality oil; group IV – 200 mg kg-1 of vitamin E + low-quality oil; group V – 100 mg kg-1 of vitamin E and 100 mg kg-1 of polyphenols + low-quality oil; group VI – 200 mg kg-1 of polyphenols + low-quality oil. Rapeseed oil oxidised under laboratory conditions was added to the diets of broiler chickens from groups II to VI. The applied antioxidants had no effect on the growth performance of chickens fed oxidised oil. Increased dietary inclusion levels of vitamin E and/or polyphenols improved the antioxidant status in the blood and increased the content of non-enzymatic antioxidants in the liver and breast muscles of broilers fed low-quality oil. The tested antioxidants had no influence on carcass quality parameters in chickens fed oxidised oil. However, birds fed diets with the addition of vitamin E were characterised by a higher gizzard weight and higher pH of gizzard digesta. Dietary supplementation with vitamin E and polyphenols or polyphenols alone contributed to a lighter colour and lower pH of breast muscles and an increase in the content of fat and ash in the breast muscles of broilers fed oxidised oil. The breast muscles of birds given 100 or 200 mg kg-1 of supplemental vitamin E were characterised by higher concentrations of n-6 polyunsaturated fatty acids (PUFAs) and hypocholesterolemic fatty acids (DFAs), a more desirable DFA/OFA ratio, and a lower atherogenicity index (AI). Polyphenols combined with vitamin E can be a valuable component of diets for broiler chickens when the problem of low-quality oil occurs.

Temporal characterization of wooden breast myopathy ("woody breast") severity and correlation with growth rate and lymphocytic phlebitis in three commercial broiler strains and a random-bred broiler strain

Wooden breast myopathy (WBM), or "woody breast" or "wooden breast" affects modern, rapidly growing, high breast-yield broiler chickens. Decreased meat quality due to undesirable organoleptic properties and condemnation of affected breast meat cause economic losses. The pathogenesis of WBM remains unknown. In this study, WBM lesion development was determined in three modern broiler strains and Athens Canadian Random Bred (ACRB) broilers, a 1950s unselected broiler chicken. Correlations between WBM severity and incubation temperature profile, sex, strain, body weight, and lymphocytic phlebitis were also determined. At 2, 4, 6, and 8 weeks of age, samples of breast muscle from 10 male and 10 female birds from each strain, incubated under optimal or low-early, high-late temperatures, were scored histologically for severity of WBM and lymphocytic phlebitis. WBM lesions, identified as early as 2 weeks, became progressively more severe with age and growth in the three commercial broiler strains. WBM severity was significantly correlated with lymphocytic phlebitis and body weight. Lymphocytic phlebitis and minimal WBM were present in the ACRB broilers at all samplings, but did not progress in severity over time. There were no significant differences in severity of WBM among the commercial broiler strains, between sexes, or between incubation temperature profiles. The positive correlation between WBM severity and lymphocytic phlebitis indicates vascular injury is likely an important factor in the pathogenesis. Mild muscle lesions in ACRB birds without overt clinical signs indicate subclinical muscle disease may have been present in broilers prior to the description of WBM.

White striping prevalence and its effect on meat quality of broiler breast fillets under commercial conditions

White striping (WS), characterized by white striations on the Pectoralis major muscle, is an emerging problem for the broiler industry. Thus, the impact of WS on meat quality has become a current research topic. In this context, a 2-year follow-up study, to reveal the prevalence of WS in broiler integrations, was undertaken. Additionally, a laboratory experiment was conducted to determine the oxidative quality during storage and the differences in proximate composition, colour and fatty acid and amino acid profiles of broiler breast fillets scored visually as normal, moderate and severe. In integrations, the WS incidence increased with increasing broiler age and more than 50% of breast fillets obtained from 32- to 35-day-old broilers and 36- to 39-day-old broilers had stripes with different scores. Lower protein and higher fat contents were measured in the moderate and severe scored fillets than the normal fillets (p < 0.001). Severe score stripes induced the formation of less redness on the ventral surface (p < 0.05) and a darker colour on the dorsal surface (p < 0.01). The lowest histidine, arginine and tryptophan amounts were determined in severe fillets (p < 0.05). Moderate and severe scored fillets were rich in polyunsaturated fatty acids implying that they were sensitive to lipid oxidation. That suggestion was further proven by the higher TBARS values. Freeze-thawing induced the formation of carbonyl compounds, but it did not cause differences in sulphydryl groups. Briefly, we suggest that different WS scores may affect the physicochemical and oxidative quality of breast fillets; however, more studies are needed to assert an accurate and explicit judgement.

Comparison of slaughter yields and some meat quality parameters in broilers reared on sepiolite-supplemented wood shavings and rice hulls

Many bedding materials have been tested in broiler industry for their suitability. However, little knowledge is available regarding the usage of different bedding materials supplemented with sepiolite and their effects on animal performance and final product quality. For this purpose, a total of 288 day-old male broiler chicks were randomly allocated into two types of bedding materials (wood shavings and rice hulls). Each bedding material group was divided into 3 sub-groups: control with 0% sepiolite, 25%-sepiolite group, and 50%-sepiolite group. Each sub-group was placed in 6 pens with 8 chicks per pen. The effects of bedding materials and sepiolite additions on slaughter yields and some meat quality parameters in broilers were evaluated. Slaughter parameters including hot carcass yield and relative weights of thigh and breast meat, heart, liver, gizzard and bursa Fabricius in broilers were not affected by bedding materials and sepiolite additions (P > 0.05). Also, no significant differences were observed among experimental groups for cooking loss and nutritional profile of breast and thigh meat of broilers (P > 0.05). The freshly measured pH0 of breast and thigh meats was significantly affected by the bedding material and was higher for wood shavings group (P < 0.01). Breast and thigh meats of broilers reared on rice hulls were lighter (P < 0.01), less red, and less yellow in color than those reared on wood shavings, whereas no effect of sepiolite additions was observed on the color of both meat cuts. No substantial effect of bedding material and sepiolite additions was observed on white stripping; however, their occurrence rate found was very high for meat of broilers reared on rice hulls than those reared on wood shavings (P > 0.05). In conclusion, broilers reared on either wood shavings or rice hulls with or without sepiolite additions did not show any negative effects on slaughter yields and meat quality parameters. Furthermore, sepiolite can be an option as a bedding material for broiler industry, but further research with thorough economic analysis is required.

The impaired quality of chicken affected by the wooden breast myopathy is counteracted in emulsion-type sausages

The aim of this study was to evaluate the suitability of using chicken meat affected by wooden breast (WB) myopathy in the production of chicken sausages. Compare the technological and sensory properties of such sausages were compared with those produced from normal (N) breast meat. Three types of chicken sausages were elaborated: 100% containing N chicken meat, 100% of WB chicken meat and 50% N/50% of WB meat. The WB chicken meat presented higher values for pH, L*, moisture, cooking loss, shear force, hardness, chewiness, adhesiveness and gumminess; while WHC and protein content were higher for N chicken meat. N and WB chicken sausages presented similar values of WHC, a*, b* color values, protein content and TBARS. QDA indicated no sensory differences between the three sausage formulations, so did the acceptability and purchase intention. Therefore, WB chicken meat may be used to produce chicken sausages combined or not with N chicken meat. Further studies, however, may be required to investigate the nutritional value and digestibility of WB meat and derived products.

White striping and wooden breast myopathies of broiler breast muscle is affected by time-limited feeding, genetic background, and egg storage

The effects of time-limited feeding, genetic background, and egg storage on white striping (WS) and wooden breast (WB) in broilers were studied. Male chicks (240) from 2 genetic backgrounds and 2 egg storage periods were fed on either an ad libitum (AL) or time-limited (TL) program from 7 d of age. A rapid growth strain (Growth) and an enhanced yield strain (Yield) of broiler breeder males were mated to a single female line and eggs were stored for periods of either 1 to 7 d or 8 to 14 d. Body weight (BW), feed consumption, and feed conversion ratio (FCR) were determined weekly. Carcass data including WS and WB scores were collected at 42 d of age. Breast muscle scoring was conducted either visually or by hand palpation using a 1 to 4 point ordinal scale (normal to greatest severity). Data were analyzed using the Mixed procedure of SAS. The TL fed broilers presented less WS (1.64 vs. 2.87) and WB (2.14 vs. 2.89), lower BW (2.99 vs. 3.27 kg), and improved FCR (1.55 vs. 1.58 g: g), as well as reduced dressing percentage (79.5 vs. 80.1%), breast muscle yield (33.3 vs. 34.6%), and 24 h muscle pH (5.82 vs. 5.95) relative to AL broilers (P < 0.01). Yield broilers exhibited reduced BW (2.97 vs. 3.28 kg), lower WS (2.04 vs. 2.47), and greater WB (2.65 vs. 2.38) (P < 0.05) but similar dressing percentage (80.0 vs. 79.7%) and breast muscle yield (34.3 vs. 33.6%) when compared to Growth broilers. Longer egg storage generated lower BW (3.07 vs. 3.18 kg) and when fed AL, an increased WS score (2.58 vs. 3.15) compared to the shorter egg storage period (P < 0.05). It was concluded that WS and WB could be reduced by TL feeding and that genetic background and egg storage period may influence the expression of WS and WB.

Near-infrared spectroscopy detects woody breast syndrome in chicken fillets by the markers protein content and degree of water binding

The muscle syndrome woody breast (WB) impairs quality of chicken fillets and is a challenge to the poultry meat industry. There is a need for online detection of affected fillets for automatic quality sorting in process. Near-infrared spectroscopy (NIRS) is a promising method, and in this study we elucidate the spectral properties of WB versus normal fillets. On a training set of 50 chicken fillets (20 normal, 30 WB), we measured NIR, nuclear magnetic resonance (NMR) T2 relaxation distributions, and crude chemical composition. NIRS could estimate protein in the fillets with an accuracy of ±0.64 percentage points. T2 distributions showed that there was a larger share of free water in WB fillets. This difference in water binding generated a shift and narrowing of the water absorption peak in NIR around 980 nm, quantified by a bound water index (BWI). The correlation between BWI and T2 distributions was 0.78, indicating that NIRS contains information about degree of water binding. Discriminant analysis showed that NIRS obtained 100% correct classification of normal versus WB on the training set, and 96% correct classification on a test set of 52 fillets. The main reason for why NIRS can successfully discriminate between WB and normal fillets is the methods sensitivity to both protein content and degree of water binding in the muscle, both established markers for WB. The classification model can be based on NIR spectra only, calibration against protein is not needed. The affected muscle tissue associated with the WB syndrome is unevenly distributed in the fillets, and this heterogeneity was characterized by NIRS and NMR. Clear differences in water binding properties were found between the superficial 1 cm layer and the deeper layer at 1 to 2 cm depth. Significant differences in protein estimates by NIRS at different measurement points along the chicken fillets were obtained for WB fillets. The findings suggest how to obtain optimal sampling with NIRS for best possible discrimination between WB and normal breast fillets.

Recent Developments in Breast Muscle Myopathies Associated with Growth in Poultry

The functional unit in skeletal muscle is the multinucleated myofiber, which is composed of parallel arrays of microfibrils. The myofiber and sarco-mere structure of skeletal muscle are established during embryogenesis, when mononuclear myoblast cells fuse to form multinucleated myotubes and develop into muscle fibers. With the myoblasts permanently unable to enter a proliferative state again after they fuse to form the multinucleated myotube, postnatal myofiber growth, muscle homeostasis, and myofiber regeneration are dependent on a myogenic stem cell, the satellite cell. Because the satellite cell is a partially differentiated stem cell controlling the state of skeletal muscle structure throughout the life of the bird, it can impact muscle development and structure, growth, and regeneration and, subsequently, meat quality. When myofibers are damaged, muscle repair is dependent on the satellite cells. Regenerated myofibers after the repair process should be similar to the original muscle fiber. Despite significant improvements in meat-type birds, degenerative myopathies have arisen. In many of these degenerative breast muscle myopathies, like Wooden Breast, satellite cell–mediated regeneration of muscle is suppressed. Thus, the biological function of avian myogenic satellite cells and their influence on cellular mechanisms affecting breast muscle development and growth, function during degenerative myopathies, and meat quality are discussed.

Wooden-Breast, White Striping, and Spaghetti Meat: Causes, Consequences and Consumer Perception of Emerging Broiler Meat Abnormalities

Ten years ago, the occurrence of macroscopic defects in breasts muscles from fast-growing broilers challenged producers and animal scientists to label and characterize myopathies wholly unknown. The distinctive white striations in breasts affected by white striping disorder, the presence of out-bulging and pale areas of hardened consistency in the so-called wooden breast, and the separation of the fiber bundles in breasts labelled as spaghetti meat, made these myopathies easily identified in chicken carcasses. Yet, the high incidence of these myopathies and the increasing concern by producers and retailers led to an unprecedented flood of questions on the causes and consequences of these abnormal chicken breasts. This review comprehensively collects the most relevant information from studies aimed to understand the pathological mechanisms of these myopathies, their physicochemical and histological characterization and their impact on meat quality and consumer's preferences. Today, it is known that the occurrence is linked to fast-growth rates of the birds and their large breast muscles. The muscle hypertrophy along with an unbalanced growth of supportive connective tissue leads to a compromised blood supply and hypoxia. The occurrence of oxidative stress and mitochondrial dysfunction leads to lipidosis, fibrosis, and overall myodegeneration. Along with the altered appearance, breast muscles affected by the myopathies display poor technological properties, impaired texture properties, and reduced nutritional value. As consumer's awareness on the occurrence of these abnormalities and the concerns on animal welfare arise, efforts are made to inhibit the onset of the myopathies or alleviate the severity of the symptoms. The lack of fully effective dietary strategies leads scientists to propose whether "slow" production systems may alternatively provide with poultry meat free of these myopathies.

Wooden breast myopathy links with poorer gait in broiler chickens

Wooden breast myopathy, a condition where broiler breast muscles show a hardened consistency post-mortem, has been described recently. However, it is not known how wooden breast myopathy affects the bird activity or welfare. Altogether, over 340 birds of five commonly used commercial hybrids were housed in 25 pens, and sample birds killed at ages of 22, 32, 36, 39 and 43 days. Their breast muscle condition was assessed post-mortem by palpation. The birds were gait scored and their latency to lie was measured before killing. For further behavior observations, one affected and healthy bird in 12 pens were followed on 5 days for 20 minutes using video recordings. The connection of myopathy to gait score and activity was analyzed with mixed models. A higher gait score of wooden-breast-affected birds than that of unaffected birds (2.9 ± 0.1 v. 2.6 ± 0.1, P < 0.05) indicated a higher level of locomotor difficulties over all age groups. The wooden-breast-affected birds had fewer crawling or movement bouts while lying down compared with unaffected (P < 0.05). Wooden breast myopathy-affected birds were heavier (2774 ± 91 v. 2620 ± 91 g; P < 0.05) and had higher breast muscle yield (21 ± 1 v. 19 ± 1%; P < 0.05) than unaffected birds overall. Older birds had longer lying bouts, longer total lying time, fewer walking bouts, more difficulties to walk and to stand compared with younger birds (P < 0.05). Birds with poorer gait had longer total lying time and fewer walking bouts (P < 0.05). Birds with greatest breast muscle yield had the largest number of lying bouts (P < 0.05). It was concluded that wooden breast myopathy was associated with an impairment of gait scores, and may thus be partly linked to the common walking abnormalities in broilers.

Gene expression profiling of the early pathogenesis of wooden breast disease in commercial broiler chickens using RNA-sequencing

Wooden Breast Disease (WBD), a myopathy in commercial broiler chickens characterized by abnormally firm consistency of the pectoral muscle, impacts the poultry industry negatively due to severe reduction in meat quality traits. To unravel the molecular profile associated with the onset and early development of WBD in broiler chickens, we compared time-series gene expression profiles of Pectoralis (P.) major muscles between unaffected and affected birds from a high-breast-muscle-yield, purebred broiler line. P. major biopsy samples were collected from the cranial and caudal aspects of the muscle belly in birds that were raised up to 7 weeks of age (i.e. market age). Three subsets of biopsy samples comprising 6 unaffected (U) and 10 affected (A) from week 2 (cranial) and 4 (caudal), and 4U and 11A from week 3 (cranial) were processed for RNA-sequencing analysis. Sequence reads generated were processed using a suite of bioinformatics programs producing differentially expressed (DE) genes for each dataset at fold-change (A/U or U/A) >1.3 and False Discovery Ratio (FDR) <0.05 (week 2: 41 genes; week 3: 618 genes and week 4: 39 genes). Functional analysis of DE genes using literature mining, BioDBnet and IPA revealed several biological processes and pathways associated with onset and progress of WBD. Top among them were dysregulation of energy metabolism, response to inflammation, vascular disease and remodeling of extracellular matrix. This study reveals that presence of molecular perturbations involving the vasculature, extracellular matrix and metabolism are pertinent to the onset and early pathogenesis of WBD in commercial meat-type chickens.

Comparison of quality traits among breast meat affected by current muscle abnormalities

Over the past several decades, as a result of the increasing growth rate and body size of modern hybrid birds, poultry industry has been facing up the occurrence of many breast meat abnormalities, such as White Striping (WS), Wooden Breast (WB) and Spaghetti Meat (SM), whose incidence has recently reached alarming levels. Thus, the present study aimed at simultaneously investigating the implications of WS, WB and SM abnormalities on meat colour, pH, proximate composition, fatty acid profile, collagen, thermal properties as well as texture and water mobility, assessed on both superficial and deep section of Pectoralis major muscle. Overall, the occurrence of breast abnormalities is associated with a higher ultimate pH and a significant increase in moisture and fat level, coupled with a decrease in protein and ash content with WB showing the most detrimental effect. However, fatty acid profile resulted to be mildly modified only by WS. Moreover, WB fillets showed significantly higher (P < .001) collagen content and stromal protein denaturation enthalpy associated with an altered water distribution and mobility within the muscle tissue. On the contrary, SM samples displayed a lower (P < .001) collagen cross-linking and a softer texture after the cooking. Overall, these findings reveal that the occurrence of WB abnormality exerts a more profound and prominent effect on meat quality traits rather than the presence not only of WS, but also of SM.

Effect of dietary arginine to lysine ratios on productive performance, meat quality, plasma and muscle metabolomics profile in fast-growing broiler chickens

Background

Due to the important functions of arginine in poultry, it should be questioned whether the currently adopted dietary Arg:Lys ratios are sufficient to meet the modern broiler requirement in arginine. The present study aimed, therefore, to evaluate the effects of the dietary supplementation of L-arginine in a commercial broiler diet on productive performance, breast meat quality attributes, incidence and severity of breast muscle myopathies and foot pad dermatitis (FPD), and plasma and muscle metabolomics profile in fast-growing broilers.

Results

A total of 1,170 1-day-old Ross 308 male chicks was divided into two experimental groups of 9 replicates each fed either a commercial basal diet (CON, digestible Arg:Lys ratio of 1.05, 1.05, 1.06 and 1.07 in each feeding phase, respectively) or the same basal diet supplemented on-top with crystalline L-arginine (ARG, digestible Arg:Lys ratio of 1.15, 1.15, 1.16 and 1.17, respectively). Productive parameters were determined at the end of each feeding phase (12, 22, 33, 43 d). At slaughter (43 d), incidence and severity of FPD and breast myopathies were assessed, while plasma and breast muscle samples were collected and analyzed by proton nuclear magnetic resonance-spectroscopy. The dietary supplementation of arginine significantly reduced cumulative feed conversion ratio compared to the control diet at 12 d (1.352 vs. 1.401, P < 0.05), 22 d (1.398 vs. 1.420; P < 0.01) and 33 d (1.494 vs. 1.524; P < 0.05), and also tended to improve it in the overall period of trial (1.646 vs. 1.675; P = 0.09). Body weight was significantly increased in ARG compared to CON group at 33 d (1,884 vs. 1,829 g; P < 0.05). No significant effect was observed on meat quality attributes, breast myopathies and FPD occurrence. ARG birds showed significantly higher plasma concentration of arginine and leucine, and lower of acetoacetate, glutamate, adenosine and proline. Arginine and acetate concentrations were higher, whereas acetone and inosine levels were lower in the breast of ARG birds (P < 0.05).

Conclusions

Taken together, these data showed that increased digestible Arg:Lys ratio had positive effects on feed efficiency in broiler chickens probably via modulation of metabolites that play key roles in energy and protein metabolism.

Oxidative stress-induced skeletal muscle injury involves in NF-κB/p53-activated immunosuppression and apoptosis response in copper (II) or/and arsenite-exposed chicken

The adverse effects of environmental toxicants such as copper and arsenic occur due to the generation of reactive oxygen species. Recent study also reported that both copper (Cu) and arsenic (As) may alter muscle regeneration. In order to assess the toxic effects of copper and arsenic on chicken skeletal muscle, chickens were subjected by different toxicologically relevant concentrations of copper or arsenic and their combination in diets for 12 weeks. Upon comparative analysis, a significantly higher malondialdehyde (MDA) and hydroxy radical content were observed in Cu or/and As exposed chicken skeletal muscle, which confirmed the strong lipid peroxidation nature of these two heavy metals. In addition, the depleted activity of catalase and glutathione peroxidase suggested the strong association of copper and arsenic with oxidative stress. Moreover, the higher elevation of pro-inflammatory mediators (NF-κB et al.) and Th1 bias immune system, suggested that exposure to Cu or/and As induces inflammation via NF-κB mediated response pathway. These results further coincided with inflammatory infiltration and nuclear condensation. Further, the execution of apoptosis machinery were characterized by a considerably elevated pro-apoptotic response and apoptotic index. In conclusion, the increased p53 levels detected in Cu or/and As treated chickens suggest the possibility that the NF-kB/p53 axis might lead to the impairment of immune-apoptosis cross talk in the present model.