Poultry Meat Quality in Relation to Muscle Growth and Muscle Fiber Characteristics

Porcine skeletal muscle typing in histochemical and in-situ RT-PCR analysis

Currently, there are plenty of histochemical methods to classify pig muscle fibers, which confused the naming and classification of muscle fibers. This study aims to analyze the difference and correlation of 6 different histochemical methods and select the most suitable method for muscle fiber classification at the molecular and histomological levels by in-situ RT-PCR and enzyme histochemical methods. Muscle fiber samples, including psoas (PM), semitendinosus (SM) and trapezius muscle (TM), were collected from Large Spotted (LS), Lantang (LT) and Landrace (LR) pigs at their market-ages (LS at 150 d, LT at 210 d, and LR at 150 d). 6 kinds of histochemical methods combining actomyosin adenosine triphosphatase (AM-ATPase) with succinate dehydrogenase (SDH) enzyme were conducted to differentiate fiber types. 2 types of fibers (I and II) were differentiated by acid 2-fibre (2-AC) or alkaline 2-fibre classification(2-AL), 3 types of fibers (βR, αR and αW) by 3-AC or 3-AL, and 4 types of fibers (I, IIa, IIx and IIb) by 4-AC, or 4-AL. Results showed that AC and AL muscle-fiber classification were consistent in reflecting the characteristics of muscle fibers(P > 0.05), but the color of each muscle fiber type was just opposite. AC methods may be superior to AL methods because of their clear staining background, the sensitivity to staining condition. But there were breed differences and tissue specificity in the optimal preincubation condition. The optimal acid preincubation condition for classifying muscle fibers was pH4.30 for LT, while pH 4.35 for the LS and LR pigs. Meanwhile the optimal acid preincubation condition was pH4.35 for PM, while pH4.40 for TM or SM. For further selection from 2, 3, 4-AC, in-situ RT-PCR was applied to detect the mRNA distribution of myosin heavy chain I (MyHC-I). By combining in-situ PCR with enzyme histochemistry methods, MyHC-I gene and its product - Type I fibrocytes were directly located in cells at both molecular level and morphological level. Compared with the cross-sectional area (CSA) of different muscle fibers (i.e. I, II, βR, αR, αW, IIa, IIx and IIb) identified by enzyme histochemistry, it was found that the CSAs with stronger mRNA expression signal of MyHC-Ⅰ were closer to those of the Type I muscle fiber measured by 4-AC enzyme histochemistry (P > 0.05). Therefore, 4-AC may be considered as the most proper muscle typing method to study muscle fiber typing as well as meat quality. And the combination of in-situ RT-PCR and histochemistry may help better understand porcine muscle fiber characteristics and meat quality in pigs.

Myostatin gene role in regulating traits of poultry species for potential industrial applications

The myostatin (MSTN) gene is considered a potential genetic marker to improve economically important traits in livestock, since the discovery of its function using the MSTN knockout mice. The anti-myogenic function of the MSTN gene was further demonstrated in farm animal species with natural or induced mutations. In poultry species, myogenesis in cell culture was regulated by modulation of the MSTN gene. Also, different expression levels of the MSTN gene in poultry models with different muscle mass have been reported, indicating the conserved myogenic function of the MSTN gene between mammalian and avian species. Recent advances of CRISPR/Cas9-mediated genome editing techniques have led to development of genome-edited poultry species targeting the MSTN gene to clearly demonstrate its anti-myogenic function and further investigate other potential functions in poultry species. This review summarizes research conducted to understand the function of the MSTN gene in various poultry models from cells to whole organisms. Furthermore, the genome-edited poultry models targeting the MSTN gene are reviewed to integrate diverse effects of the MSTN gene on different traits of poultry species.

Regulation of myo-miR-24-3p on the Myogenesis and Fiber Type Transformation of Skeletal Muscle

Skeletal muscle plays critical roles in providing a protein source and contributing to meat production. It is well known that microRNAs (miRNAs) exert important effects on various biological processes in muscle, including cell fate determination, muscle fiber morphology, and structure development. However, the role of miRNA in skeletal muscle development remains incompletely understood. In this study, we observed a critical miRNA, miR-24-3p, which exhibited higher expression levels in Tongcheng (obese-type) pigs compared to Landrace (lean-type) pigs. Furthermore, we found that miR-24-3p was highly expressed in the dorsal muscle of pigs and the quadriceps muscle of mice. Functionally, miR-24-3p was found to inhibit proliferation and promote differentiation in muscle cells. Additionally, miR-24-3p was shown to facilitate the conversion of slow muscle fibers to fast muscle fibers and influence the expression of GLUT4, a glucose transporter. Moreover, in a mouse model of skeletal muscle injury, we demonstrated that overexpression of miR-24-3p promoted rapid myogenesis and contributed to skeletal muscle regeneration. Furthermore, miR-24-3p was found to regulate the expression of target genes, including Nek4, Pim1, Nlk, Pskh1, and Mapk14. Collectively, our findings provide evidence that miR-24-3p plays a regulatory role in myogenesis and fiber type conversion. These findings contribute to our understanding of human muscle health and have implications for improving meat production traits in livestock.

Comparative analyses of dynamic transcriptome profiles highlight key response genes and dominant isoforms for muscle development and growth in chicken

BACKGROUND

Modern breeding strategies have resulted in significant differences in muscle mass between indigenous chicken and specialized broiler. However, the molecular regulatory mechanisms that underlie these differences remain elusive. The aim of this study was to identify key genes and regulatory mechanisms underlying differences in breast muscle development between indigenous chicken and specialized broiler.

RESULTS

Two time-series RNA-sequencing profiles of breast muscles were generated from commercial Arbor Acres (AA) broiler (fast-growing) and Chinese indigenous Lushi blue-shelled-egg (LS) chicken (slow-growing) at embryonic days 10, 14, and 18, and post-hatching day 1 and weeks 1, 3, and 5. Principal component analysis of the transcriptome profiles showed that the top four principal components accounted for more than 80% of the total variance in each breed. The developmental axes between the AA and LS chicken overlapped at the embryonic stages but gradually separated at the adult stages. Integrative investigation of differentially-expressed transcripts contained in the top four principal components identified 44 genes that formed a molecular network associated with differences in breast muscle mass between the two breeds. In addition, alternative splicing analysis revealed that genes with multiple isoforms always had one dominant transcript that exhibited a significantly higher expression level than the others. Among the 44 genes, the TNFRSF6B gene, a mediator of signal transduction pathways and cell proliferation, harbored two alternative splicing isoforms, TNFRSF6B-X1 and TNFRSF6B-X2. TNFRSF6B-X1 was the dominant isoform in both breeds before the age of one week. A switching event of the dominant isoform occurred at one week of age, resulting in TNFRSF6B-X2 being the dominant isoform in AA broiler, whereas TNFRSF6B-X1 remained the dominant isoform in LS chicken. Gain-of-function assays demonstrated that both isoforms promoted the proliferation of chicken primary myoblasts, but only TNFRSF6B-X2 augmented the differentiation and intracellular protein content of chicken primary myoblasts.

CONCLUSIONS

For the first time, we identified several key genes and dominant isoforms that may be responsible for differences in muscle mass between slow-growing indigenous chicken and fast-growing commercial broiler. These findings provide new insights into the regulatory mechanisms underlying breast muscle development in chicken.

Role of Clove and Tulsi on broiler health and meat production

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

LncRNA-TBP mediates TATA-binding protein recruitment to regulate myogenesis and induce slow-twitch myofibers

BACKGROUND

Skeletal muscle is comprised of heterogeneous myofibers that differ in their physiological and metabolic parameters. Of these, slow-twitch (type I; oxidative) myofibers have more myoglobin, more mitochondria, and higher activity of oxidative metabolic enzymes compared to fast-twitch (type II; glycolytic) myofibers.

METHODS

In our previous study, we found a novel LncRNA-TBP (for "LncRNA directly binds TBP transcription factor") is specifically enriched in the soleus (which has a higher proportion of slow myofibers). The primary myoblast cells and animal model were used to assess the biological function of the LncRNA-TBP in vitro or in vivo. Meanwhile, we performed a RNA immunoprecipitation (RIP) and pull-down analysis to validate this interaction between LncRNA-TBP and TBP.

RESULTS

Functional studies demonstrated that LncRNA-TBP inhibits myoblast proliferation but promotes myogenic differentiation in vitro. In vivo, LncRNA-TBP reduces fat deposition, activating slow-twitch muscle phenotype and inducing muscle hypertrophy. Mechanistically, LncRNA-TBP acts as a regulatory RNA that directly interacts with TBP protein to regulate the transcriptional activity of TBP-target genes (such as KLF4, GPI, TNNI2, and CDKN1A).

CONCLUSION

Our findings present a novel model about the regulation of LncRNA-TBP, which can regulate the transcriptional activity of TBP-target genes by recruiting TBP protein, thus modulating myogenesis progression and inducing slow-twitch fibers. Video Abstract.

Probiotic mixture (Bacillus subtilis and Bacillus licheniformis) a potential in-feed additive to improve broiler production efficiency, nutrient digestibility, caecal microflora, meat quality and to diminish hazardous odour emission

This research aimed to assess the impact of probiotic supplementation in the broiler diet on growth performance, nutrient utilization, noxious gas emissions, excreta micromiota and meat quality. One thousand six hundred and twenty male Ross 380 broilers (one-day-old, body weight, 42 ± 0.5 g and 5-week trial) were arbitrarily chosen and assigned to three nutritive treatments (basal diet and basal diet included with 0.1%, and 0.2% probiotic mixture [Bacillus subtilis 7.0 × 10⁷ cfu/g, Bacillus licheniformis 4.1 × 10⁷ cfu/g]) with 30 duplicates (18 birds each). Probiotic inclusion linearly increased (p < 0.05) broiler body weight gain (BWG) during Phases 1, 2 and the overall period and decreased (p < 0.05) feed conversion ratio (FCR) linearly on Phase 2 and the overall period. However, feed intake (FI) and mortality rate remained unaffected (p > 0.05). Though nutrient digestibility of nitrogen (N) tendency to increase (p < 0.05), dry matter (DM) and energy (E) did not influence (p > 0.05). Inclusion of a probiotic supplement linearly increased (p < 0.05) Lactobacillus and reduced Salmonella (p < 0.05) counts in broilers. Moreover, broilers fed a diet supplement with probiotic addition linearly decreased (p < 0.05) NH₃ , H₂ S, C₂ O and acetic acid emissions. The graded level of probiotic addition linearly reduced (p < 0.05) cooking loss and the tendency to decrease (p < 0.05) weight of bursa of Fabricius, but had no effect (p > 0.05) on other meat quality measures. These findings indicated that increasing the level of probiotics in feed could improve growth efficiency, nutrient absorption, microbial index, meat quality and reduce gas emissions in broilers.

Transcriptome sequencing analysis of the role of miR-499-5p and SOX6 in chicken skeletal myofiber specification

MicroRNAs (miRNAs) might play critical roles in skeletal myofiber specification. In a previous study, we found that chicken miR-499-5p is specifically expressed in slow-twitch muscle and that its potential target gene is SOX6. In this study, we performed RNA sequencing to investigate the effects of SOX6 and miR-499-5p on the modulation and regulation of chicken muscle fiber type and its regulatory mechanism. The expression levels of miR-499-5p and SOX6 demonstrated opposing trends in different skeletal muscles and were associated with muscle fiber type composition. Differential expression analysis revealed that miR-499-5p overexpression led to significant changes in the expression of 297 genes in chicken primary myoblasts (CPMs). Myofiber type-related genes, including MYH7B and CSRP3, showed expression patterns similar to those in slow-twitch muscle. According to functional enrichment analysis, differentially expressed genes were mostly associated with muscle development and muscle fiber-related processes. SOX6 was identified as the target gene of miR-499-5p in CPM using target gene mining and luciferase reporter assays. SOX6 knockdown resulted in upregulation of the slow myosin genes and downregulation of fast myosin genes. Furthermore, protein-protein interaction network analysis revealed that MYH7B and RUNX2 may be the direct targets of SOX6. These results indicated that chicken miR-499-5p may promote slow-twitch muscle fiber formation by repressing SOX6 expression. Our study provides a dataset that can be used as a reference for animal meat quality and human muscle disease studies.

Growth Performance and Meat Quality of Growing Pigs Fed with Black Soldier Fly (Hermetia illucens) Larvae as Alternative Protein Source

Insects have been used as animal feed protein sources in livestock and poultry breeding, and their impact on pork quality needs to be studied. This experiment mainly explores the effect of adding black soldier flies to the feed on the growth performance and meat quality of pigs. All 24 weaned piglets were randomly divided into three groups, one group was given a normal diet as the control group (C), and the other two groups were supplemented with 4% (T1) and 8% (T2) black soldier flies as an alternative protein source, respectively. Pig growth performance and carcass traits were measured at the end of the 113-day experiment. After euthanizing the pigs, we used metabolomics to detect pig dorsal muscle and qPCR to detect gene expression in dorsal muscle and adipose tissue. For the average daily gain and backfat thickness, T2 group was significantly higher than T1 group and C group (p < 0.05). Intramuscular fat content was significantly elevated in the T1 and T2 groups (p < 0.05). The metabolomics results showed that there were significant differences in metabolites among the three groups (p < 0.05). The addition of black soldier flies could increase the content of some free amino acids, and the content of lipid metabolites also changed significantly (p < 0.05). The gene expression of type 1 muscle fibers in the T1 group and the PGC-1α gene expression in the T1 and T2 groups were significantly increased in the dorsal muscle (p < 0.05). The results of the present study showed that adding 4% black soldier fly instead of fish meal in the diet of growing pigs can significantly improve meat quality and supplementation of 8% black soldier flies has beneficial effects on growth performance of pigs.

Regulation of Non-Coding RNA in the Growth and Development of Skeletal Muscle in Domestic Chickens

Chicken is the most widely consumed meat product worldwide and is a high-quality source of protein for humans. The skeletal muscle, which accounts for the majority of chicken products and contains the most valuable components, is tightly correlated to meat product yield and quality. In domestic chickens, skeletal muscle growth is regulated by a complex network of molecules that includes some non-coding RNAs (ncRNAs). As a regulator of muscle growth and development, ncRNAs play a significant function in the development of skeletal muscle in domestic chickens. Recent advances in sequencing technology have contributed to the identification and characterization of more ncRNAs (mainly microRNAs (miRNAs), long non-coding RNAs (LncRNAs), and circular RNAs (CircRNAs)) involved in the development of domestic chicken skeletal muscle, where they are widely involved in proliferation, differentiation, fusion, and apoptosis of myoblasts and satellite cells, and the specification of muscle fiber type. In this review, we summarize the ncRNAs involved in the skeletal muscle growth and development of domestic chickens and discuss the potential limitations and challenges. It will provide a theoretical foundation for future comprehensive studies on ncRNA participation in the regulation of skeletal muscle growth and development in domestic chickens.

Genome-Wide Association Study of Potential Meat Quality Trait Loci in Ducks

With continuously increasing living standards and health requirements of consumers, meat quality is becoming an important consideration while buying meat products. To date, no genome-wide association study (GWAS) for copy number variants (CNVs) and single nucleotide polymorphisms (SNPs) has been conducted to reveal the genetic effects on meat quality in ducks. This study analyzed the phenotypic correlation and heritability of fat, water, collagen, and protein content of duck breast muscle. To identify the candidate variants for meat quality, we performed a GWAS using 273 ducks from an F2 population. The results of the SNP GWAS showed that the BARHL2, COPS7B, and CCDC50 genes were associated with fat content; BLM, WDR76, and EOMES with water content; CAMTA1, FGD5, GRM7, and RAPGEF5 with collagen production; and RIMS2, HNRNPU, and SPTBN1 with protein content. Additionally, 3, 7, 1, and 3 CNVs were associated with fat, water, collagen, and protein content, respectively, in duck breast muscle. The genes identified in this study can serve as markers for meat quality. Furthermore, our findings may help devise effective breeding plans and selection strategies to improve meat quality.

Comparison of Physicochemical Characteristics and Sensory Attributes of Four Different Chicken Breeds from the Genuine and Selected Local Market

Village chicken is known as a high-quality product perception and sold at high prices. However, the authenticity of village chicken is doubted because colored chicken has been claimed as village chicken to fraud the consumers and to gain high profit. No stringent strategy has been implemented by the local authority on the authenticity of the claimed village chickens. Thus, the study aimed to determine the meat quality of different chicken breeds including village chicken, broiler chicken (Cobb), colored chicken (Hubbard), and layer chicken from genuine suppliers and chickens sold at different local markets based on the physicochemical characterization, textural properties, and sensory evaluation. Chicken breeds were obtained from genuine suppliers and slaughtered at the slaughtering house Universiti Putra Malaysia. Proximate composition, color, and textural properties were evaluated. Minitab-19 and SIMCA-13 software were used to analyze the results, applying analysis of variance and partial least squares discriminant analysis, respectively. The study revealed that some of the market-supplied chickens were not authentic based on the features studied. About 20% of market village chickens had possessed similar results as the control village chicken. It can be shown that 80% of the claimed village chicken sold in the market was not authentic village chicken. This study showed the differentiation in texture composition such as chewiness, hardness, gumminess, cohesiveness, resilience, and springiness, followed by protein content, ash content, and a ${}^{\ast }$ and b ${}^{\ast }$ values as an indicator to differentiate the authenticity of different chicken breeds.

Telomere Length, Apoptotic, and Inflammatory Genes: Novel Biomarkers of Gastrointestinal Tract Pathology and Meat Quality Traits in Chickens under Chronic Stress (Gallus gallus domesticus)

Simple Summary

The assessment of poultry’s gastrointestinal (GI) tract and meat quality traits are crucial for sustainable poultry production in the tropics. The search for well-conserved and more reliable biomarkers for the GI tract and meat traits has faced many challenges. In this study, we observed the effect of corticosterone (CORT) and age on body weight, buffy coat telomere length, GI tract, and meat quality traits. The critical evaluation of the GI tract and meat traits in this study revealed that telomere length, mitochondria, and acute phase protein genes were altered by chronic stress and were associated with the traits. This study informed us of the potential of telomere length, mitochondria, and acute phase protein genes in the assessment of GI tract pathological conditions and meat quality in the poultry sector for sustainable production.

Abstract

This study was designed to examine the potentials of telomere length, mitochondria, and acute phase protein genes as novel biomarkers of gastrointestinal (GI) tract pathologies and meat quality traits. Chickens were fed a diet containing corticosterone (CORT) for 4 weeks and records on body weight, telomere length, GI tract and muscle histopathological test, meat quality traits, mitochondria, and acute phase protein genes were obtained at weeks 4 and 6 of age. The body weight of CORT-fed chickens was significantly suppressed (p < 0.05). CORT significantly altered the GI tract and meat quality traits. The interaction effect of CORT and age on body weight, duodenum and ileum crypt depth, pH, and meat color was significant (p < 0.05). CORT significantly (p < 0.05) shortened buffy coat telomere length. UCP3 and COX6A1 were diversely and significantly expressed in the muscle, liver, and heart of the CORT-fed chicken. Significant expression of SAAL1 and CRP in the liver and hypothalamus of the CORT-fed chickens was observed at week 4 and 6. Therefore, telomere lengths, mitochondria, and acute phase protein genes could be used as novel biomarkers for GI tract pathologies and meat quality traits.

RNA Profiles of the Korat Chicken Breast Muscle with Increased Carnosine Content Produced through Dietary Supplementation with β-Alanine or L-Histidine

Simple Summary

Carnosine is a bioactive food component with several potential health benefits for humans due to its physiological functions. Dietary supplementation with β-alanine or L-histidine can increase the carnosine content of skeletal muscles in chickens. Dietary supplementation with β-alanine or L-histidine has produced a slow-growing chicken variety with high carnosine content in the breast meat; however, the supplementation with L-histidine alone softens the meat toughness, which may affect consumers’ willingness to buy the meat. Gene expression is a key factor that influences meat quality. Understanding the molecular mechanisms that affect carnosine content and meat toughness would allow the production of more value-added slow-growing chickens. We compared global gene expression in chicken breast muscles with differing carnosine contents and meat toughness produced through dietary supplementation with β-alanine or L-histidine. We identified differentially expressed genes involved in regulating myosin, collagen, intramuscular fat, and calpain—factors that may affect meat tenderness. Pathway enrichment analysis indicated that the insulin-related and adipocytokine signaling pathways were altered by dietary supplementation with β-alanine or L-histidine. These data will be useful for future studies on carnosine content and meat toughness in slow-growing chickens.

Abstract

Korat chicken (KRC) is a slow-growing chicken bred in Thailand, whose meat exhibits a unique toughness. A previous study produced KRC breast meat containing high carnosine content through dietary supplementation with β-alanine or L-histidine; however, the KRC that were fed an L-histidine-supplemented diet produced meat that was significantly more tender. Herein, we performed RNA-Seq to identify candidate genes involved in the regulation of carnosine content and meat toughness. Total RNA was isolated from five female KRC breast muscles in each treatment group that KRC fed diets without supplementation, supplemented with β-alanine or L-histidine. Compared to the non-supplemented group, we identified 118 and 198 differentially expressed genes (DEGs) in the β-alanine or L-histidine supplementation groups, respectively. Genes potentially related to meat tenderness—i.e., those regulating myosin, collagen, intramuscular fat, and calpain—were upregulated (LOC107051274, ACSBG1, and CAPNS2) and downregulated (MYO7B, MYBPH, SERPINH1, and PGAM1). However, carnosine synthase gene was not identified. Functional enrichment analysis identified pathways affected by dietary supplementation, including the insulin signaling pathway (β-alanine supplementation) and the insulin resistance and adipocytokine signaling pathways (L-histidine supplementation). The FoxO signaling pathway was identified as a regulatory network for both supplementation groups. The identified genes can be used as molecular markers of meat tenderness in slow-growing chickens.

Sensory Quality Evaluation of Superheated Steam-Treated Chicken Leg and Breast Meats with a Combination of Marination and Hot Smoking

As the sensory qualities of meat processed using methods such as superheated steam, marination, and hot smoking have not been examined, this study analyzed the sensory quality of chicken meats (leg, breast) and its chemical correlation by determining optimal processing conditions (superheated steam treatment, marination, and hot smoking). Chicken meats were defrosted using room temperature, running tap water, or high-frequency defroster. Marinated meats with herbal extract solution were treated with superheated steam and then hot smoked with wood sawdust; sensory evaluations were performed at each processing step. The products were analyzed for fatty acids and nutrients, along with storage tests under different conditions. High-frequency defrosting showed the lowest drip loss and thawing time compared to other methods. Bay leaves and oak wood were selected as the best sub-materials for higher sensory scores. Optimal superheated steam conditions showed higher overall acceptance (8.86, 8.71) and were set as follows; leg meat (225 °C; 12 min 20 s), breast meat (223 °C; 8 min 40 s). The final meat products possessed good nutritional composition and no severe sensory spoilages were detected during storage despite microbial and chemical degradations. Thus, regular sensory evaluations at each processing step and storage condition were effective for developing superior chicken meat products.

Carnosine Content and Its Association with Carnosine-Related Gene Expression in Breast Meat of Thai Native and Black-Bone Chicken

This study aimed to investigate the carnosine content and ATP-grasp domain-containing protein 1 (CARNS1) gene expression and their relationship with breast meat of Black Chinese (BC), KU-Phuparn (KP), Pradu Hang Dam (PD), and Black Chinese × Pradu Hang Dam (Sri Mok: SM) to aid in the selection and mating programs for developing functional meat in Thai chicken populations. The results show that the carnosine content in each breed and breed group varied from 428.08 to 553.93 mg/100 g, whereas the relative expression of CARNS1 ranged from 0.84 to 1.56. The BC and KP chicken breeds had a higher carnosine content (p < 0.01) and higher CARNS1 expression level (p < 0.05) than the SM and PD chicken breeds. The carnosine content and relative gene expression for each age ranged from 423.02 to 577.83 mg/100 g and 0.68 to 1.83, respectively. At 4 weeks of age, the carnosine content (p < 0.01) and gene expression (p < 0.05) were the highest. However, they decreased as chicken age increased further. The carnosine content and gene expression linearly decreased as chicken age increased (p < 0.01). The correlation coefficient between the level of gene expression and carnosine content was moderately positive. The results from this study showed that different breeds and ages of chickens have different amounts of carnosine, and CARNS1 could act as a biomarker to study marker-assisted selection to improve functional meat in the chicken population in Thailand.

Influence of yeast hydrolysate supplement on growth performance, nutrient digestibility, microflora, gas emission, blood profile, and meat quality in broilers

A total of 1512 Ross 308 broilers (one - day - old) were assigned (random blocks) to 1of 3 dietary treatments with 28 replicates of 18 chicks/cage. The dietary treatments were Corn-soybean-meal based basal diet supplemented with 0%, 0.1%, and 0.2% of commercial yeast hydrolysate (YH [Saccharomyces cerevisiae]). The graded level of YH supplementation has linearly increased broilers body weight gain on d 21, 35, and overall (p = 0.044, 0.029, and 0.036, respectively) experimental period. In addition, the increased level of YH supplementation has linearly reduced feed conversation ratio of broilers on d 21, 35, and overall trial period (p = 0.041, 0.052, and 0.032, respectively). However, the feed intake and mortality of broilers were not affected by the graded level of YH supplementation. Though nutrient digestibility of dry matter (p = 0.012) and nitrogen (p = 0.021) was linearly increased in broilers fed YH supplementation, at the end of the trial it fails to affect the total track digestible energy. Dietary inclusion of YH supplementation showed a beneficial effect on the microbial population as linearly improved lactobacillus (p = 0.011) and reduced Escherichiacoli counts (p = 0.042). An increasing level of YH supplementation has tended to decrease NH₃ (p = 0.069) and linearly decrease H₂S (p = 0.027) of noxious gas emission in broilers. Moreover, dietary YH supplements trend to increase the glucose (p = 0.066) and reduced cholesterol (p = 0.069) level. At the end of the test, YH supplementation elicited a linear reduction in drip loss on days 5 and 7, respectively (p = 0.045, and 0.021). Furthermore, dietary inclusion of YH supplementation had linearly increased villus height (p = 0.051) but fails to affect crypt depth. Therefore, in terms of positive effects on the broiler’s overall performance, we suggest that dietary supplements containing graded YH levels in the broilers diet could serve as a potential alternative for growth promoters.

LncRNA-FKBP1C regulates muscle fiber type switching by affecting the stability of MYH1B

Long non-coding RNAs (lncRNAs) are well-known to participate in a variety of important regulatory processes in myogenesis. In our previous RNA-seq study (accession number GSE58755), we found that lncRNA-FKBP1C was differentially expressed between White Recessive Rock (WRR) and Xinghua (XH) chicken. Here, we have further demonstrated that lncRNA-FKBP1C interacted directly with MYH1B by biotinylated RNA pull-down assay and RNA immunoprecipitation (RIP). Protein stability and degradation experiments identified that lncRNA-FKBP1C enhanced the protein stability of MYH1B. Overexpression of lncRNA-FKBP1C inhibited myoblasts proliferation, promoted myoblasts differentiation, and participated in the formation of skeletal muscle fibers. LncRNA-FKBP1C could downregulate the fast muscle genes and upregulate slow muscle genes. Conversely, its interference promoted cell proliferation, repressed cell differentiation, and drove the transformation of slow-twitch muscle fibers to fast-twitch muscle fibers. Similar results were observed after knockdown of the MYH1B gene, but the difference was that the MYH1B gene had no effects on fast muscle fibers. In short, these data demonstrate that lncRNA-FKBP1C could bound with MYH1B and enhance its protein stability, thus affecting proliferation, differentiation of myoblasts and conversion of skeletal muscle fiber types.

Study on the transcriptome for breast muscle of chickens and the function of key gene RAC2 on fibroblasts proliferation

BACKGROUND

Growth performance is significant in broiler production. In the growth process of broilers, gene expression varies at different growth stages. However, limited research has been conducted on the molecular mechanisms of muscle growth and development in yellow-feathered male chickens.

RESULTS

In the study, we used RNA-seq to study the transcriptome of the breast muscle of male Jinghai yellow chickens at 4 (M4F), 8 (M8F) and 12 weeks (M12F) of age. The results showed that 4608 differentially expressed genes (DEGs) were obtained by comparison in pairs of the three groups with Fold Change (FC) ≥ 2 and False Discovery Rate (FDR) ≤ 0.05, and 83, 3445 and 3903 DEGs were obtained separately from M4FvsM8F, M4FvsM12F and M8FvsM12F. Six genes were found as co-differentially expressed in the three age groups, namely SNCG, MYH1A, ARHGDIB, ENSGALG00000031598, ENSGALG00000035660 and ENSGALG00000030559. The GO analysis showed that 0, 304 and 408 biological process (BP) were significantly enriched in M4FvsM8F, M4FvsM12F and M8FvsM12F groups, respectively. KEGG pathway enrichment showed that 1, 2, 4 and 4 pathways were significantly enriched in M4FvsM8F, M4FvsM12F, M8FvsM12F and all DEGs, respectively. They were steroid biosynthesis, carbon metabolism, focal adhesion, cytokine-cytokine receptor interaction, biosynthesis of amino acids and salmonella infection. We constructed short hairpin RNA (shRNA) to interfere the differentially expressed gene RAC2 in DF-1 cells and detected mRNA and protein expression of the downstream genes PAK1 and MAPK8. Results of qPCR showed that RAC2, PAK1 and MAPK8 mRNA expression significantly decreased in the shRAC2-2 group compared with the negative control (NC) group. Western Blot (WB) results showed that the proteins of RAC2, PAK1 and MAPK8 also decreased in the shRAC2-2 group. Cell Counting Kit-8 (CCK-8) and 5-Ethynyl-2'-deoxyuridine (EdU) assay both showed that the proliferation of DF-1 cells was significantly inhibited after transfection of shRAC2-2.

CONCLUSIONS

The results of RNA-seq revealed genes, BP terms and KEGG pathways related to growth and development of male Jinghai yellow chickens, and they would have important guiding significance to our production practice. Further research suggested that RAC2 might regulate cell proliferation by regulating PAKs/MAPK8 pathway and affect growth of chickens.

Comparative effect of dietary Morinda lucida leaf and Butylated hydroxyanisole (BHA) on carcass traits, meat quality, and oxidative stability of broiler chickens

This study examined the impact of dietary supplementation of Morinda lucida leaf powder (MLLP) and Butylated hydroxyanisole (BHA) on carcass traits, physicochemical properties, and sensory attributes of different muscles in broiler chickens. Two hundred and forty 1-day old Arbor acre chicks were randomly allotted to either a negative control (NC), basal diet without additive; M-0.1, basal diet + 0.1%MLLP; M-0.2, basal diet + 0.2%MLLP; or Positive Control, (PC), basal diet + 0.02%BHA, fed for 42 d, and euthanized. The physicochemical properties and oxidative stability of thigh and breast muscles were assessed over a 5 d postmortem chill storage. Diet had no effect (p > 0.05) on carcass traits and chemical composition, cook loss, pH and sensory attributes of breast and thigh muscles in broiler chickens. Total phenolic content was higher (p = 0.032) in the supplemented meats than in the NC meat. Carbonyl content, TBARS value and drip loss were higher (p < 0.05), while redness was lower (p = 0.021) in the NC meat compared with the meat of the supplemented birds. Carbonyl content was lower (p < 0.0001) in the PC meat compared with the M-0.1 and M-0.2 meats. The M-0.1 and M-0.2 meats had lower (p < 0.0001) TBARS value than the PC meat. Chill storage and muscle type influenced (p < 0.05) the physicochemical properties and oxidative stability of broiler meat. There were significant interactions between diet, muscle type, and chill storage on the oxidative stability of broiler meat. These results suggest that MLLP exhibited antioxidant potential that was comparable to that of BHA in the diets of broiler chickens.

Effects of marketable ages on meat quality through fiber characteristics in the goose

Goose meat is increasingly popular among consumers because of its good quality. The fiber characteristics have been well demonstrated to be key contributing factors of meat quality, and the marketable ages are also closely related to meat quality. However, little is known about the effect of different marketable ages on the quality of goose meat through its fiber characteristics. Here, fiber characteristics of Yangzhou geese of different marketable ages (70, 90, and 120 d) and their effect on meat quality were investigated. The results showed that only fast-twitch fibers were present in breast muscle, irrespective of age, and that few slow-twitch fibers could be identified in leg muscle, especially in gastrocnemius and extensor digitorum longus. Fiber diameter in breast muscle increased rapidly from age 70 d to 90 d, from 19.88 to 26.27 μm, and remained stable for 90 d thereafter. The diameter and cross-sectional area of muscle fiber continue to grow with day increasing in leg muscle. In addition, we measured the proximate composition and physical properties at different ages. Among the 3 marketable ages investigated, the 120-day-old geese had higher intramuscular fat and protein content, as well as lower moisture content, both in breast and leg meat. Greater lightness and pressing loss, with lower redness and shear force, were observed in the breast and leg meat of 70-day-old geese when compared with 90- or 120-day-old geese. Taken together, although older marketable age hardly affected muscle fiber type in geese, it would contribute to larger muscle fiber area, higher intramuscular fat and protein content, as well as redder and chewier meat. As a result, the reasonable marketable age should be taken into account to improve quality in goose meat production, and the marketable age of 90 or 120 d was recommended and it could potentially improve meat quality in goose meat production.

Physico-chemical attributes, sensory evaluation and oxidative stability of leg meat from broilers supplemented with plant extracts

This feeding trial was conducted to investigate the effects of Mentha arvensis (MA) and Geranium thunbergii (GT) in drinking water on physicochemical attributes, sensory qualities, proximate analysis and oxidative stability of broiler leg meat. One hundred and twenty broiler chicks were assigned to 1 of 4 dietary treatments for 5 weeks. The dietary treatments were 1) control, 2) T1 (0.1% 1 MA:1 GT), 3) T2 (0.1% 1 MA:4 GT), 4) T3 (0.1% 4 MA: 1 GT). The water holding capacity and cooking loss were improved (p < 0.05) in T2 and T3. The flavor, texture and acceptability of leg meat by consumers were significantly increased in T2 relative to the control (p < 0.05). The crude protein content was increased in T3 while the crude fat decreased in T2 (p < 0.05). Moreover, broilers supplemented with plant extracts had the lowest leg meat TBARS (thiobarbituric acid reactive substances) values after 2 weeks of storage as compared with the control. Total phenolic contents and 1-1-diphenyl 2 picrylhydrazyl (DPPH) activity were also better in the T2 group (p < 0.05) compared with the control, whereas 2,2-Azinobis-3 ethytlbenzothiazoline-6-sulfonic acid (ABTS⁺) remained unaffected. Overall, these results demonstrate that broiler drinking water with the inclusion of plant extract combination can be used to enhance the oxidative stability, shelf life and quality characteristics of broiler leg meat without compromising the growth performance.

miRNA-mRNA network regulation in the skeletal muscle fiber phenotype of chickens revealed by integrated analysis of miRNAome and transcriptome

Skeletal muscle fibers are primarily categorized into oxidative and glycolytic fibers, and the ratios of different myofiber types are important factors in determining livestock meat quality. However, the molecular mechanism for determining muscle fiber types in chickens was hardly understood. In this study, we used RNA sequencing to systematically compare mRNA and microRNA transcriptomes of the oxidative muscle sartorius (SART) and glycolytic muscle pectoralis major (PMM) of Chinese Qingyuan partridge chickens. Among the 44,705 identified mRNAs in the two types of muscles, 3,457 exhibited significantly different expression patterns, including 2,364 up-regulated and 1,093 down-regulated mRNAs in the SART. A total of 698 chicken miRNAs were identified, including 189 novel miRNAs, among which 67 differentially expressed miRNAs containing 42 up-regulated and 25 down-regulated miRNAs in the SART were identified. Furthermore, function enrichment showed that the differentially expressed mRNAs and miRNAs were involved in energy metabolism, muscle contraction, and calcium, peroxisome proliferator-activated receptor (PPAR), insulin and adipocytokine signaling. Using miRNA-mRNA integrated analysis, we identified several candidate miRNA-gene pairs that might affect muscle fiber performance, viz, gga-miR-499-5p/SOX6 and gga-miR-196-5p/CALM1, which were supported by target validation using the dual-luciferase reporter system. This study revealed a mass of candidate genes and miRNAs involved in muscle fiber type determination, which might help understand the molecular mechanism underlying meat quality traits in chickens.

Identification of differentially expressed genes and pathways between intramuscular and abdominal fat-derived preadipocyte differentiation of chickens in vitro

BACKGROUND

The distribution and deposition of fat tissue in different parts of the body are the key factors affecting the carcass quality and meat flavour of chickens. Intramuscular fat (IMF) content is an important factor associated with meat quality, while abdominal fat (AbF) is regarded as one of the main factors affecting poultry slaughter efficiency. To investigate the differentially expressed genes (DEGs) and molecular regulatory mechanisms related to adipogenic differentiation between IMF- and AbF-derived preadipocytes, we analysed the mRNA expression profiles in preadipocytes (0d, Pre-) and adipocytes (10d, Ad-) from IMF and AbF of Gushi chickens.

RESULTS

AbF-derived preadipocytes exhibited a higher adipogenic differentiation ability (96.4% + 0.6) than IMF-derived preadipocytes (86.0% + 0.4) (p < 0.01). By Ribo-Zero RNA sequencing, we obtained 4403 (2055 upregulated and 2348 downregulated) and 4693 (2797 upregulated and 1896 downregulated) DEGs between preadipocytes and adipocytes in the IMF and Ad groups, respectively. For IMF-derived preadipocyte differentiation, pathways related to the PPAR signalling pathway, ECM-receptor interaction and focal adhesion pathway were significantly enriched. For AbF-derived preadipocyte differentiation, the steroid biosynthesis pathways, calcium signaling pathway and ECM-receptor interaction pathway were significantly enriched. A large number of DEGs related to lipid metabolism, fatty acid metabolism and preadipocyte differentiation, such as PPARG, ACSBG2, FABP4, FASN, APOA1 and INSIG1, were identified in our study.

CONCLUSION

This study revealed large transcriptomic differences between IMF- and AbF-derived preadipocyte differentiation. A large number of DEGs and transcription factors that were closely related to fatty acid metabolism, lipid metabolism and preadipocyte differentiation were identified in the present study. Additionally, the microenvironment of IMF- and AbF-derived preadipocyte may play a significant role in adipogenic differentiation. This study provides valuable evidence to understand the molecular mechanisms underlying adipogenesis and fat deposition in chickens.

Growth Performance and Characterization of Meat Quality of Broiler Chickens Supplemented with Betaine and Antioxidants under Cyclic Heat Stress

Heat stress (HS) causes oxidative stress, which compromises broiler performance and meat quality. The aim of this study was to determine whether dietary antioxidants could be used as an amelioration strategy. Seventy-two day-old-male Ross-308 chicks were exposed to either thermoneutral or cyclical heat stress conditions. Diets were either control commercial diet (CON), CON plus betaine (BET), or with a combination of betaine, selenized yeast, and vitamin E (BET + AOX). Heat stress increased the rectal temperature (p < 0.001), respiration rate (p < 0.001), decreased blood pCO₂ (p = 0.002), and increased blood pH (p = 0.02), which indicated the HS broilers had respiratory alkalosis. Final body weight was decreased by HS (p < 0.001), whereas it was improved with BET (p = 0.05). Heat stress reduced cooking loss (p = 0.007) and no effect on drip loss, while BET decreased the drip loss (p = 0.01). Heat stress reduced the myofibril fragmentation index (p < 0.001) and increased thiobarbituric acid reactive substances (p < 0.001), while these were improved with the combination of BET + AOX (p = 0.003). In conclusion, BET overall improved growth rates and product quality in this small university study, whereas some additional benefits were provided by AOX on product quality in both TN and HS broilers.

Inactivation of Pseudomonas deceptionensis CM2 on chicken breasts using plasma-activated water

The aim of this study was to examine the effectiveness of plasma-activated water (PAW) for inactivating Pseudomonas deceptionensis CM2 on chicken breasts. Sterile distilled water (SDW) was activated by gliding arc discharge plasma for 60 s, which was defined as PAW60. The chicken breast samples inoculated P. deceptionensis CM2 were dipped in PAW60 or SDW for the indicated time intervals, respectively. After the treatment of PAW60 for 12 min, the population of P. deceptionensis CM2 on chicken breast was significantly reduced by 1.05 log₁₀ CFU/g (p < 0.05), which was higher than that of SDW-treated samples for the same time intervals (p < 0.05). The L* value of chicken breasts were increased whereas a* and b* values were decreased following PAW60 treatment, while there was no significant differences in the values of a* and b* between PAW60- and SDW-treated samples for the same time intervals (p > 0.05). As compared with SDW, PAW60 caused no significant changes in the texture characteristics (e.g. hardness, springiness, cohesiveness and gumminess) and sensory properties (e.g. appearance, color, odor, texture, acceptability). Thus, PAW can be very effective to improve microbiological safety of chicken breasts with resulting slight changes to the sensory qualities. This synergistic treatment of PAW with other non-thermal technologies should be well investigated in order to improve inactivation efficacy of PAW.

Transcriptome profile analysis of leg muscle tissues between slow- and fast-growing chickens

Chicken is widely favored by consumers because of some unique features. The leg muscles occupy an important position in the market. However, the specific mechanism for regulating muscle growth speed is not clear. In this experiment, we used Jinghai yellow chickens with different body weights at 300 days as research subjects. The chickens were divided into fast- and slow-growing groups, and we collected leg muscles after slaughtering for use in RNA-seq. After comparing the two groups, 87 differentially expressed genes (DEGs) were identified (fold change ≥ 2 and FDR < 0.05). The fast-growing group had 42 up-regulated genes and 45 down-regulated genes among these DEGs compared to the slow-growing group. Six items were significantly enriched in the biological process: embryo development ending in birth or egg hatching, chordate embryonic development, embryonic skeletal system development, and embryo development as well as responses to ketones and the sulfur compound biosynthetic process. Two significantly enriched pathways were found in the KEGG pathway analysis (P-value < 0.05): the insulin signaling pathway and the adipocytokine signaling pathway. This study provides a theoretical basis for the molecular mechanism of chicken growth and for improving the production of Jinghai yellow chicken.