MEATabolomics: Muscle and Meat Metabolomics in Domestic Animals

Effect of frozen storage on the untargeted and targeted metabolites of flavored roasted beef using UHPLC-MS/MS and GC-MS

In this study, we investigated the changes in untargeted metabolites using UHPLC-MS/MS and the flavors of nonflavored (BS1) and flavored (BS2) roasted beef using GC-MS throughout a 6-month frozen period. A total of 509, 659, and 496 metabolites met the conditions for differential screening, and 56, 103, and 47 differential metabolites were recognized between BS1 and BS2 at 0, 3, and 6 months of frozen periods, respectively. The total relative abundance of organic nitrogen compounds, phenylpropanoids, polyketides, organic acids and their derivatives, and benzenoids increased during frozen storage at 3 months and then decreased at 6 months. A total of 16 differential metabolites were identified as markers for prolonged freezing, which belong to organic acids and their derivatives (Asp-Val-Lys, Val-Lys, Met-Phe, Tyr-Leu, N(6)-(octanoyl)lysine, and cis-acetylacrylate), lipids and lipid-like molecules (2,3-dimethyl-3-hydroxyglutaric acid, PC(P-16:0/2:0), (S)-17-hydroxy-9,11,13,15-octadecatetraynoic acid, PC(18:1(9Z)/18:1(11Z)), LysoPC (20:4(8Z,11Z,14Z,17Z)/0:0), PC(20:5/0:0), PE(20:3(8Z,11Z,14Z)/18:4(6Z,9Z,12Z,15Z)), and PS(14:1(9Z)/22:0)), and others (putrescine and phenylacetaldehyde). Sixty-three volatile flavor compounds were detected, and their concentrations were decreased along with frozen storage, except for aldehydes. Positive correlations were observed between volatiles and free amino acids. Therefore, frozen storage has a notable effect on the metabolite profiles of roasted beef.

Insights into high-altitude adaptation and meat quality regulation by gastrointestinal metabolites in Tibetan and black pigs

Introduction

Tibetan pigs, native to the Qinghai-Tibet Plateau, have adapted over millennia to extreme conditions such as low oxygen, harsh cold, and high UV radiation, impacting their muscle characteristics and digestive tract microbiota. The quality of pork from Tibetan pigs (TP) and black pigs (BP) is influenced by various factors, including genetics, diet, and environmental adaptation. However, the specific influence of digestive tract microbiota metabolites on muscle traits remains poorly understood. Our goal was to correlate omic variations with meat quality traits and identify potential biomarkers predictive of superior meat quality, elucidate the regulatory effects of digestive tract microbial metabolites on Tibetan pig muscle characteristics, and reveal the genetic and nutritional mechanisms that promote adaptation to extreme environmental conditions.

Methods

This analysis encompassed metabolomic profiling of the entire digestive tract-including the stomach, jejunum, cecum, colon, and rectum-as well as histological, amino acid, fatty acid composition, and transcriptomic assessments of the longissimus dorsi muscle tissues to investigate how digestive tract microbial metabolites influence muscle adaptation to high altitudes.

Results

Analyses revealed that Tibetan pig muscles contain smaller, more oxidative fibers enriched with flavor-enhancing amino acids. This was accompanied by a more favorable n-6/n-3 fatty acid ratio. Distinct patterns of microbial metabolites were observed in the digestive tract, influencing protein digestion and purine metabolism, and correlating with muscle glycine levels. Transcriptomic data showed varied gene expression in metabolic pathways related to salivary and pancreatic secretion, as well as carbohydrate and fatty acid metabolism. Integrated multi-omics approaches linked stomach metabolism, particularly through bile secretion pathways influenced by acetylcholine, to muscle functionality, highlighting the important role played by the ATP1B4 gene in enabling muscle physiology in Tibetan pigs.

Discussion

This study highlights the importance of targeted dietary interventions in improving meat quality for specific pig breeds. It also provides a theoretical foundation for precision agriculture strategies aimed at enhancing the meat quality of both TP and BP pigs.

Creatine monohydrate administration delayed muscle glycolysis of antemortem-stressed broilers by enhancing muscle energy status, increasing antioxidant capacity and regulating muscle metabolite profiles

Preslaughter stress induced a negative energy balance of broilers, resulted in an accelerated glycolysis and finally led to an inferior meat quality. The present study aimed to investigate the effects of creatine monohydrate (CMH) supplementation on muscle energy storage, antioxidant capacity, the glycolysis of postmortem muscle and the metabolite profiles in muscle of broilers subjected to preslaughter transport. Two hundred and forty broilers were chosen and randomly allocated into three treatments (group A, group B and group C), comprising 8 replicates (10 broilers each replicate). Broilers in group A and B as well as group C were fed with the basal diet or diets containing 1200 mg/kg CMH for 14 days, respectively. After 12 h feed deprivation, broilers in group B (T3h group) and group C (T3h +CMH1200 group) were both subjected to a preslaughter transportation (3 h), but those in group A were treated with a 0.5 h-transport (refined as the control group). The results showed that preslaughter stress led to a lower pH24h value, a bigger L* value and a higher drip loss of muscle compared with the control group (P < 0.05). In addition, transport stress accelerated glycolysis in postmortem muscle, decreased energy storage and the antioxidant capacities of muscle (P < 0.05). However, CMH administration ameliorated energy status, delayed muscle glycolysis, elevated mRNA expression involved in Cr metabolism and inhibited AMPK signaling of broilers experienced preslaughter transport stress. Moreover, significant differences in glycine, serine and threonine metabolism, cysteine and methionine metabolism, purine metabolism, arginine and proline metabolism, ABC transporters, carbon metabolism, lysine metabolism and sulfur metabolism were observed using pathway enrichment analysis. Additionally, the contents of Cr and ATP were positively correlated with branched amino acids (L-valine and l-leucine), l-asparagine, inosine, PCr and d-ribose by metabolomics analysis. Taken together, CMH ameliorated energy status, delayed muscle glycolysis and improved meat quality of antemortem-stressed broilers by the regulation of pathways and key metabolites involved in energy metabolism of postmortem muscle.

Multi-omics reveals the molecular mechanism of muscle quality changes in common carp (Cyprinus carpio) under two aquaculture systems

Preliminary experiments in our laboratory have demonstrated that common carp (Cyprinus carpio) cultivated for two months in land-based container recirculating aquaculture systems (C-RAS) exhibit superior muscle quality compared to those raised in traditional pond systems (TP). To elucidate the molecular mechanisms underlying muscle quality variations in common carp cultured under two aquaculture systems, transcriptomic and metabolomic analyses were performed on muscle tissues of specimens aged 11 to 23 months. Comparison of muscle histological sections between the two groups indicated a significantly lower long diameter of muscle fibers in the C-RAS group compared to the TP group (P < 0.01). Conversely, the muscle fiber density was significantly higher in the C-RAS group than in the TP group (P < 0.05). Transcriptomic and metabolomic analyses identified 3390 differentially expressed genes (DEGs)-1558 upregulated and 1832 downregulated-and 181 differentially expressed metabolites (DEMs)-124 upregulated and 57 downregulated-between the groups. Based on integrated transcriptomic and metabolomic analyses, the significant differences focus on metabolic pathways involving glycolysis/gluconeogenesis, arginine and proline metabolism, arginine biosynthesis, and purine metabolism. The study revealed that the muscle quality of common carp in two aquaculture systems is primarily regulated through improvements in energy metabolism, amino acid metabolism, fatty acid metabolism, and purine metabolism. These metabolic processes play significant roles in promoting muscle fiber hyperplasia and hypertrophy, enhancing muscle flavor, and increasing muscle antioxidant capacity. This study provides new insights into the molecular and metabolic pathways that control muscle quality in common carp under different environmental factors.

Evaluating protocols for reproducible targeted metabolomics by NMR

Metabolomics aims to study the downstream effects of variables like diet, environment, or disease on a given biological system. However, inconsistencies in sample preparation, data acquisition/processing protocols lead to reproducibility and accuracy concerns. A systematic study was conducted to assess how sample preparation methods and data analysis platforms affect metabolite susceptibility. A targeted panel of 25 metabolites was evaluated in 69 clinical metabolomics samples prepared following three different protocols: intact, ultrafiltration, and protein precipitation. The resulting metabolic profiles were characterized by 1D 1H nuclear magnetic resonance (NMR) spectroscopy and analyzed with Chenomx v8.3 and SMolESY software packages. Greater than 90% of the metabolites were extracted more efficiently using protein precipitation than filtration, which aligns with previously reported results. Additionally, analysis of data processing software suggests that metabolite concentrations were overestimated by Chenomx batch-fitting, which only appears reliable for determining relative fold changes rather than absolute quantification. However, an assisted-fit method provided sufficient guidance to achieve accurate results while avoiding a time-consuming fully manual-fitting approach. By combining our results with previous studies, we can now provide a list of 5 common metabolites [2-hydroxybutyrate (2-HB), choline, dimethylamine (DMA), glutamate, lactate] with a high degree of variability in reported fold changes and standard deviations that need careful consideration before being annotated as potential biomarkers. Our results show that sample preparation and data processing package critically impact clinical metabolomics study success. There is a clear need for an increased degree of standardization and harmonization of methods across the metabolomics community to ensure reliable outcomes.

Lipidome and metabolome profiling of longissimus lumborum beef with different ultimate pH and postmortem aging

The objective of this exploratory study was to assess the changes on lipidome and metabolome profiling of Longissimus lumborum bull muscle with different ultimate pH (pHu) and aging periods. The bull muscles classified as normal, intermediate, or high pHu were collected from a Brazilian commercial slaughterhouse, cut into steaks, individually vacuum-packaged, and aged for 3 days (3-d) or 21 days (21-d) at 2 °C. Muscle extracts were analyzed for the profiles of both lipids, by mass spectrometry (via direct flow-injection), and metabolites, by nuclear magnetic resonance, with downstream multivariate data analysis. As major results, pairwise comparisons identified C12:0 and C14:0 acylcarnitines as potential biomarkers of the intermediate pHu-muscle, which are related to lipid catabolism for alternative energy metabolism and indicate less protein breakage postmortem. Interestingly, the concentration of arginine at early postmortem aging (3-d) may influence the previously reported improved tenderness in normal and high pHu-muscles. Moreover, upregulation of fumarate, formate, and acetate with increased pHu muscle at 21-d aging indicate more intense tricarboxylic acid cycle, amino acid degradation, and pyruvate oxidation by reactive oxygen species, respectively. These three compounds (fumarate, formate, and acetate) discriminated statistically the muscle with high pHu at 21-d aging. The normal pHu-muscle showed higher concentrations of glycogenolysis and glycolysis metabolites, including glucose, mannose, and pyruvate. Hence, our results enhance knowledge of postmortem biochemical changes of beef within different pHu groups aged up to 21 days, which is essential to understand the mechanisms underpinning bull meat quality changes.

Widely Targeted Metabolomic Analysis Reveals Dynamic Metabolic Changes in Yanbian Cattle during Dry-Aging Process

Dry-aging is a postmortem process that can substantially enhance the texture and flavour of beef. This study entailed suspending Yanbian cattle M. gluteus medius in the aging cabinet, maintained at a temperature of 2-4 °C and a relative humidity of 85 ± 5% for 35 days. Throughout this period, samples were systematically collected every 7 days. The widely targeted metabolomic analysis has been used in this investigation to analyse the dynamic changes in Yanbian cattle metabolites during dry-aging. A total of 883 metabolites were identified, with amino acids and their metabolites representing the largest proportion. Multivariate statistical analysis showed that 373 metabolites were identified as differential metabolites that changed significantly during the dry-aging process, including metabolites of amino acids, glycerophospholipids, and nucleotides and their metabolites. Additionally, 308 metabolites exhibited various increasing trends with time in dry-aging. The analysis of KEGG pathway analysis showed that ABC transporters, glycerophospholipid, and arachidonic acid metabolism are the most important metabolic pathways during dry-aging. These findings can guide technological developments in the meat processing sector and provide valuable insights into the metabolic traits and pathways of Yanbian cattle during the dry-aging process.

Leveraging Functional Genomics for Understanding Beef Quality Complexities and Breeding Beef Cattle for Improved Meat Quality

Consumer perception of beef is heavily influenced by overall meat quality, a critical factor in the cattle industry. Genomics has the potential to improve important beef quality traits and identify genetic markers and causal variants associated with these traits through genomic selection (GS) and genome-wide association studies (GWAS) approaches. Transcriptomics, proteomics, and metabolomics provide insights into underlying genetic mechanisms by identifying differentially expressed genes, proteins, and metabolic pathways linked to quality traits, complementing GWAS data. Leveraging these functional genomics techniques can optimize beef cattle breeding for enhanced quality traits to meet high-quality beef demand. This paper provides a comprehensive overview of the current state of applications of omics technologies in uncovering functional variants underlying beef quality complexities. By highlighting the latest findings from GWAS, GS, transcriptomics, proteomics, and metabolomics studies, this work seeks to serve as a valuable resource for fostering a deeper understanding of the complex relationships between genetics, gene expression, protein dynamics, and metabolic pathways in shaping beef quality.

Metabolomics Reveals Glycerophospholipids, Peptides, and Flavonoids Contributing to Breast Meat Flavor and Benefit Properties of Beijing-You Chicken

Unique metabolites contribute to the performance of meat flavor and potential function. In this study, UHPLC-Q Exactive HF-X-based metabolomics and multivariate analysis were applied to explore the characteristic metabolites in the breast meat of Beijing-You chicken (BYC) aged 150, 300, and 450 days (D150, D300, and D450). Based on the criteria of variable importance in the projection (VIP) > 1 and p < 0.05, a total of 154 and 97 differential metabolites (DMs) were screened out compared with D450 (D450 vs. D150, D450 vs. D300), respectively. In general, the relative content of carnosine, L-L-homoglutathione, demethyloleuropein, neohesperidin dihydrochalcone, 7-chloro-2-(3,4-dimethoxyphenyl)-3,5-dihydroxy-6,8-dimethoxy-4H-chromen-4-one, glycerophospholipids, exhibited the highest abundance at D450, while balenine, anserine, L-beta-aspartyl-L-leucine, glutathione, oxidized glutathione, stearoylcarnitine, ganoderic acid alpha, oleuroside, Lysoglycerophospholipid species (LGP) presented a downward trend with age. These 210 DMs were involved in 10 significantly enriched pathways related to the synthesis and metabolism of amino acids, peptides, and glycerophospholipid, such as glutathione metabolism, histidine metabolism, glycerophospholipid metabolism, arginine biosynthesis, tyrosine metabolism, and lysine degradation. In conclusion, this work could not only facilitate a better understanding of the differences of chicken flavor and benefit properties with age, but also provide potential valuable bioactive compounds for further research.

Dietary supplementation with Neolamarckia cadamba leaf extract improves broiler meat quality by enhancing antioxidant capacity and regulating metabolites

This study was to evaluate the effect of supplementing the diet of broilers with Neolamarckia cadamba leaf extract (NCLE) on meat quality by evaluating antioxidant parameters and the expression of genes in the p38 mitogen-activated protein kinase/nuclear factor-erythroid 2-related factor 2/antioxidant responsive element (p38 MAPK/Nrf2/ARE) signaling pathway, coupled with LC-MS-based metabolomic analysis. A total of 480 one-day-old male broilers were randomly allocated to four treatment groups-a control (CON) group, which was fed a basal diet, and three NCLE treatment groups, which were fed the basal diet supplemented with 100, 200, or 400 mg/kg NCLE (N1, N2, and N3 groups, respectively) for 42 d. Compared with the CON group, meat quality was improved in the N2 and N3 groups, as evidenced by the higher pH45min (P < 0.05) and lower shear force (P < 0.05) in breast muscle (BM) and lower drip loss at 48 h (P < 0.05) in leg muscle (LM). Moreover, BM antioxidant capacity was significantly enhanced in the N3 group, characterized by an increase in the total antioxidant capacity (T-AOC), the concentrations of glutathione peroxidase (GSH-Px) and catalase (CAT), and the relative mRNA expression of p38 MAPK, extracellular-signal regulated kinase (ERK1/2), c-Jun N-terminal kinase (JNK), Nrf2, CAT, and GSH-Px (P < 0.05). Similarly, LM in the N3 group displayed higher T-AOC, increased GSH-Px and CAT concentrations, reduced malonaldehyde contents (P < 0.05), and upregulation of the relative mRNA levels of JNK, Nrf2, heme oxygenase, CAT, and superoxide dismutase (SOD) (P < 0.05). Metabolomics analysis revealed that D-arabinono-1,4-lactone and lyso-PAF C-16-d4 were negatively correlated with shear force and cooking loss (P < 0.05) and displayed increased abundance in BM of the N3 group. L-Serine levels were upregulated while D-fructose 1,6-diphosphate contents were downregulated in the three NCLE groups. Finally, the differential metabolites in both BM and LM were involved in amino acid metabolism pathways. Our results indicated that NCLE supplementation improved meat quality by enhancing antioxidant enzyme activities, promoting the expression of genes in the p38 MAPK/Nrf2/ARE signaling pathway, and regulating amino acid metabolism. The optimal NCLE concentration was found to be 400 mg/kg.

Integrative Metabolomics, Enzymatic Activity, and Gene Expression Analysis Provide Insights into the Metabolic Profile Differences between the Slow-Twitch Muscle and Fast-Twitch Muscle of Pseudocaranx dentex

The skeletal muscles of teleost fish encompass heterogeneous muscle types, termed slow-twitch muscle (SM) and fast-twitch muscle (FM), characterized by distinct morphological, anatomical, histological, biochemical, and physiological attributes, driving different swimming behaviors. Despite the central role of metabolism in regulating skeletal muscle types and functions, comprehensive metabolomics investigations focusing on the metabolic differences between these muscle types are lacking. To reveal the differences in metabolic characteristics between the SM and FM of teleost, we conducted an untargeted metabolomics analysis using Pseudocaranx dentex as a representative model and identified 411 differential metabolites (DFMs), of which 345 exhibited higher contents in SM and 66 in FM. KEGG enrichment analysis showed that these DFMs were enriched in the metabolic processes of lipids, amino acids, carbohydrates, purines, and vitamins, suggesting that there were significant differences between the SM and FM in multiple metabolic pathways, especially in the metabolism of energy substances. Furthermore, an integrative analysis of metabolite contents, enzymatic activity assays, and gene expression levels involved in ATP-PCr phosphate, anaerobic glycolysis, and aerobic oxidative energy systems was performed to explore the potential regulatory mechanisms of energy metabolism differences. The results unveiled a set of differential metabolites, enzymes, and genes between the SM and FM, providing compelling molecular evidence of the FM achieving a higher anaerobic energy supply capacity through the ATP-PCr phosphate and glycolysis energy systems, while the SM obtains greater energy supply capacity via aerobic oxidation. These findings significantly advance our understanding of the metabolic profiles and related regulatory mechanisms of skeletal muscles, thereby expanding the knowledge of metabolic physiology and ecological adaptation in teleost fish.

Genome-wide association analysis explores the genetic loci of amino acid content in duck's breast muscle

BACKGROUND

Amino acids are the basic components of protein and an important index to evaluate meat quality. With the rapid development of genomics, candidate regions and genes affecting amino acid content in livestock and poultry have been gradually revealed. Hence, genome-wide association study (GWAS) can be used to screen candidate loci associated with amino acid content in duck meat.

RESULT

In the current study, the content of 16 amino acids was detected in 358 duck breast muscles. The proportion of Glu to the total amino acid content was relatively high, and the proportion was 0.14. However, the proportion of Met content was relatively low, at just 0.03. By comparative analysis, significant differences were found between males and females in 3 amino acids, including Ser, Met, and Phe. In addition, 12 SNPs were significantly correlated with Pro content by GWAS analysis, and these SNPs were annotated by 7 protein-coding genes; 8 significant SNPs were associated with Tyr content, and these SNPs were annotated by 6 protein-coding genes. At the same time, linkage disequilibrium (LD) analysis was performed on these regions with significant signals. The results showed that three SNPs in the 55-56 Mbp region of chromosome 3 were highly correlated with the leader SNP (chr3:55526954) that affected Pro content (r2 > 0.6). Similarly, LD analysis showed that there were three SNPs in the 21.2-21.6 Mbp region of chromosome 13, which were highly correlated with leader SNP (chr13:21421661) (r2 > 0.6). Moreover, Through functional enrichment analysis of all candidate genes. The results of GO enrichment analysis showed that several significant GO items were associated with amino acid transport function, including amino acid transmembrane transport and glutamine transport. The results further indicate that these candidate genes are closely associated with amino acid transport. Among them, key candidate genes include SLC38A1. For KEGG enrichment analysis, CACNA2D3 and CACNA1D genes were covered by significant pathways.

CONCLUSION

In this study, GWAS analysis found a total of 28 significant SNPs affecting amino acid content. Through gene annotation, a total of 20 candidate genes were screened. In addition, Through LD analysis and enrichment analysis, we considered that SERAC1, CACNA2D3 and SLC38A1 genes are important candidate genes affecting amino acid content in duck breast muscle.

A review of the role of transcription factors in regulating adipogenesis and lipogenesis in beef cattle

In the past few decades, genomic selection and other refined strategies have been used to increase the growth rate and lean meat production of beef cattle. Nevertheless, the fast growth rates of cattle breeds are often accompanied by a reduction in intramuscular fat (IMF) deposition, impairing meat quality. Transcription factors play vital roles in regulating adipogenesis and lipogenesis in beef cattle. Meanwhile, understanding the role of transcription factors in regulating adipogenesis and lipogenesis in beef cattle has gained significant attention to increase IMF deposition and meat quality. Therefore, the aim of this paper was to provide a comprehensive summary and valuable insight into the complex role of transcription factors in adipogenesis and lipogenesis in beef cattle. This review summarizes the contemporary studies in transcription factors in adipogenesis and lipogenesis, genome-wide analysis of transcription factors, epigenetic regulation of transcription factors, nutritional regulation of transcription factors, metabolic signalling pathways, functional genomics methods, transcriptomic profiling of adipose tissues, transcription factors and meat quality and comparative genomics with other livestock species. In conclusion, transcription factors play a crucial role in promoting adipocyte development and fatty acid biosynthesis in beef cattle. They control adipose tissue formation and metabolism, thereby improving meat quality and maintaining metabolic balance. Understanding the processes by which these transcription factors regulate adipose tissue deposition and lipid metabolism will simplify the development of marbling or IMF composition in beef cattle.

Data-independent acquisition-based SWATH-MS proteomics profiling to decipher the impact of farming system and chicken strain and discovery of biomarkers of authenticity in organic versus antibiotic-free chicken meat

In the literature, there is a paucity of methods and tools that allow the identification of biomarkers of authenticity to discriminate organic and non-organic chicken meat products. Shotgun proteomics is a powerful tool that allows the investigation of the entire proteome of a muscle and/or meat sample. In this study, a shotgun proteomics approach using Sequential Window Acquisition of All Theoretical Mass Spectra (SWATH-MS) has been applied for the first time to characterize and identify candidate protein biomarkers of authenticity in post-mortem chicken Pectoralis major muscles produced under organic and non-organic farming systems (antibiotic-free). The proteomics characterization was further performed within two chicken strains, these being Ross 308 and Ranger Classic, which differ in their growth rate. From the candidate protein biomarkers, the bioinformatics enrichment analyses revealed significant differences in the muscle proteome between the two chicken strains, which may be related to their genetic background and rearing conditions. The results further provided novel insights on the potential interconnected pathways at interplay that are associated with the differences as a consequence of farming system of chicken strain, such as muscle contraction and energy metabolism. This study could pave the way to more in-depth investigations in proteomics applications to assess chicken meat authenticity and better understand the impact of farming systems on the chicken muscle and meat quality.

Depth of Interbreed Difference in Postmortem Bovine Muscle Determined by CE-FT/MS and LC-FT/MS Metabolomics

Japanese Brown (JBR) cattle have moderately marbled beef compared to the highly marbled beef of Japanese Black (JBL) cattle; however, their skeletal muscle properties remain poorly characterized. To unveil interbreed metabolic differences over the previous results, we explored the metabolome network changes before and after postmortem 7-day aging in the trapezius muscle of the two cattle breeds by employing a deep and high-coverage metabolomics approach. Using both capillary electrophoresis (CE) and ultra-high-performance liquid chromatography (UHPLC)-Fourier transform mass spectrometry (FT/MS), we detected 522 and 384 annotated peaks, respectively, across all muscle samples. The CE-based results showed that the cattle were clearly separated by breed and postmortem age in multivariate analyses. The metabolism related to glutathione, glycolysis, vitamin K, taurine, and arachidonic acid was enriched with differentially abundant metabolites in aged muscles, in addition to amino acid (AA) metabolisms. The LC-based results showed that the levels of bile-acid-related metabolites, such as tauroursodeoxycholic acid (TUDCA), were high in fresh JBR muscle and that acylcarnitines were enriched in aged JBR muscle, compared to JBL muscle. Postmortem aging resulted in an increase in fatty acids and a decrease in acylcarnitine in the muscles of both cattle breeds. In addition, metabolite set enrichment analysis revealed that JBR muscle was distinctive in metabolisms related to pyruvate, glycerolipid, cardiolipin, and mitochondrial energy production, whereas the metabolisms related to phosphatidylethanolamine, nucleotide triphosphate, and AAs were characteristic of JBL. This suggests that the interbreed differences in postmortem trapezius muscle are associated with carnitine/acylcarnitine transport, β-oxidation, tricarboxylic acid cycle, and mitochondrial membrane stability, in addition to energy substrate and AA metabolisms. These interbreed differences may characterize beef quality traits such as the flavor intensity and oxidative stability.

Ruminal microbiota and muscle metabolome characteristics of Tibetan plateau yaks fed different dietary protein levels

Introduction

The dietary protein level plays a crucial role in maintaining the equilibrium of rumen microbiota in yaks. To explore the association between dietary protein levels, rumen microbiota, and muscle metabolites, we examined the rumen microbiome and muscle metabolome characteristics in yaks subjected to varying dietary protein levels.

Methods

In this study, 36 yaks were randomly assigned to three groups (n = 12 per group): low dietary protein group (LP, 12% protein concentration), medium dietary protein group (MP, 14% protein concentration), and high dietary protein group (HP, 16% protein concentration).

Results

16S rDNA sequencing revealed that the HP group exhibited the highest Chao1 and Observed_species indices, while the LP group demonstrated the lowest. Shannon and Simpson indices were significantly elevated in the MP group relative to the LP group (P < 0.05). At the genus level, the relative abundance of Christensenellaceae_R-7_group in the HP group was notably greater than that in the LP and MP groups (P < 0.05). Conversely, the relative abundance of Rikenellaceae_RC9_gut_group displayed an increasing tendency with escalating feed protein levels. Muscle metabolism analysis revealed that the content of the metabolite Uric acid was significantly higher in the LP group compared to the MP group (P < 0.05). The content of the metabolite L-(+)-Arabinose was significantly increased in the MP group compared to the HP group (P < 0.05), while the content of D-(-)-Glutamine and L-arginine was significantly reduced in the LP group (P < 0.05). The levels of metabolites 13-HPODE, Decanoylcarnitine, Lauric acid, L-(+)-Arabinose, and Uric acid were significantly elevated in the LP group relative to the HP group (P < 0.05). Furthermore, our observations disclosed correlations between rumen microbes and muscle metabolites. The relative abundance of NK4A214_group was negatively correlated with Orlistat concentration; the relative abundance of Christensenellaceae_R-7_group was positively correlated with D-(-)-Glutamine and L-arginine concentrations.

Discussion

Our findings offer a foundation for comprehending the rumen microbiome of yaks subjected to different dietary protein levels and the intimately associated metabolic pathways of the yak muscle metabolome. Elucidating the rumen microbiome and muscle metabolome of yaks may facilitate the determination of dietary protein levels.

Metabolomics Changes in Meat and Subcutaneous Fat of Male Cattle Submitted to Fetal Programming

This study investigated changes in meat and subcutaneous fat metabolomes and possible metabolic pathways related to prenatal nutrition in beef cattle. For this purpose, 18 Nellore bulls were used for meat sampling and 15 for fat sampling. The nutritional treatments during the gestation were: NP-not programmed or control, without protein-energy supplementation; PP-partially programmed, with protein-energy supplementation (0.3% of body weight (BW)) only in the final third of pregnancy; and FP-full programming, with protein-energy supplementation (0.3% of BW) during the entire pregnancy. The meat and fat samples were collected individually 24 h after slaughter, and the metabolites were extracted using a combination of chemical reagents and mechanical processes and subsequently quantified using liquid chromatography or flow injection coupled to mass spectrometry. The data obtained were submitted to principal component analysis (PCA), analysis of variance (ANOVA), and functional enrichment analysis, with a significance level of 5%. The PCA showed an overlap between the treatments for both meat and fat. In meat, 25 metabolites were statistically different between treatments (p ≤ 0.05), belonging to four classes (glycerophospholipids, amino acids, sphingolipids, and biogenic amine). In fat, 10 significant metabolites (p ≤ 0.05) were obtained in two classes (phosphatidylcholine and lysophosphatidylcholine). The functional enrichment analysis showed alterations in the aminoacyl-tRNA pathway in meat (p = 0.030); however, there was no pathway enriched for fat. Fetal programming influenced the meat and fat metabolomes and the aminoacyl-tRNA metabolic pathway, which is an important candidate for the biological process linked to meat quality and related to fetal programming in beef cattle.

Effects of maternal calcium propionate supplementation on offspring productivity and meat metabolomic profile in sheep

This study determined the effect of dietary calcium propionate (CaPr) as a source of energy supplementation during the First Half of Gestation (FMG), the Second Half of Gestation (SMG), and during All Gestation (AG), on offspring post-weaning growth performance, meat quality, and meat metabolomic profile. Thirty-one pregnant ewes were assigned to one of four treatments: a) supplementation of 30 gd-1 of CaPr during the first half of gestation (day 1 to day 75, n = 8) (FMG); b) supplementation of 30 gd-1 of CaPr during the second half of gestation (day 76 to day 150, n = 8) (SMG); c) supplementation of 30 gd-1 of CaPr during all gestation (AG, n = 8); d) no CaPr supplementation (control; CS, n = 7). The ewes were ad libitum fed a basal diet based on oat hay and corn silage. Ewes were distributed in a completely randomized unbalanced design to four treatments. The FMG group had lower (P ≤ 0.05) birth weight and weaning weight than the CS group. However, the average daily gain was similar across all treatments. Empty body weight and FMG had lower values (P ≤ 0.05) than the other groups. Both FMG and AG had lower hot carcass weight (P ≤ 0.05) compared to CS, while CaPr treatments resulted in reduced hot carcass yield (P ≤ 0.05). Meat color and texture were similar among treatments. A principal component analysis between gestation stages showed a trend for separating CS and FMG from SMG and AG, and that was explained by 93.7% of the data variability (PC1 = 87.9% and PC2 = 5.8%). Regarding meat metabolomic profile, 23 compounds were positively correlated between all treatments. Only 2 were negatively correlated (eicosane and naphthalene 1,2,3); but tetradecanoic acid, hexadecane, undecane 5-methyl, (-)-alpha, hexadecenoic acid, octadecanoic acid, and octadecane had a highly significant correlation (P ≤ 0.05). Overall, dam supplementation with CaPr during different periods of gestation provoked changes in meat metabolites related to the biosynthesis of fatty acids in lambs without negative changes in lamb's growth performance and carcass quality.

Changes in physical architecture and lipids compounds in skeletal muscle from Pekin duck and Liancheng white duck

As a complex food, meat displays various biochemical properties that are determined to a great extent by physical architecture and lipid metabolites. Pekin duck and Liancheng white duck are elite breeds with distinct characteristics. Here, we explored the development of the muscle fibers from embryonic stage to 10-wk after birth, and muscle fibers grow slowly after 8-wk. We investigated the meat quality, ultrastructure, lipidomics profiling, and lipids spatial distribution of skeletal muscle at 8 wk. Pekin duck has lower Warner-Bratzler shear force (WBSF) (P < 0.05), high intramuscular fat (IMF) (P < 0.01), longer and wider sarcomere, and higher mitochondrial density (P < 0.001). Liancheng white duck with tighter collagen architecture. A total of 950 lipids from 6 lipid classes identified with lipidomics were analyzed, the levels of GP, GL, and PR were significantly higher in Pekin duck (P < 0.05), SL and ST were significantly higher in Liancheng white duck (P < 0.05). There were 333 significantly different lipids (|log2(Fold Change)| ≥ 1 and FDR < 0.05) screened, most lipids distributed in the muscle tissue were uniform, but some specifically distributed in connective tissue. To some extent, the results demonstrate the high lipid deposition capacity of Pekin duck and the high medicinal function of Liancheng white duck. Our study provides new insights into the relationship between skeletal muscle architecture and meat toughness, which increased the knowledge of lipidomic characteristics and provide a basis for duck meat authentication.

Checkmeat: A Review on the Applicability of Conventional Meat Authentication Techniques to Cultured Meat

The cultured meat industry is continuously evolving due to the collective efforts of cultured meat companies and academics worldwide. Though still technologically limited, recent reports of regulatory approvals for cultured meat companies have initiated the standards-based approach towards cultured meat production. Incidents of deception in the meat industry call for fool-proof authentication methods to ensure consumer safety, product quality, and traceability. The cultured meat industry is not exempt from the threats of food fraud. Meat authentication techniques based on DNA, protein, and metabolite fingerprints of animal meat species needs to be evaluated for their applicability to cultured meat. Technique-based categorization of cultured meat products could ease the identification of appropriate authentication methods. The combination of methods with high sensitivity and specificity is key to increasing the accuracy and precision of meat authentication. The identification of markers (both physical and biochemical) to differentiate conventional meat from cultured meat needs to be established to ensure overall product traceability. The current review briefly discusses some areas in the cultured meat industry that are vulnerable to food fraud. Specifically, it targets the current meat and meat product authentication tests to emphasize the need for ensuring the traceability of cultured meat.

Metabolic and microbial analyses of the surface and inner part of wet-aged and dry-aged beef

The effects of aging and microbial growth on the metabolome of aged beef were investigated in this study. The metabolome of beef is influenced by the aging method applied. This includes the aging-related changes in metabolism and the presence of microorganisms on the beef during aging that may affect the beef and its quality. The inner part and the trimmed surface of dry-aged (the surface of dry-aged beef is also called the "crust" due to its drying during aging) and wet-aged beef were analyzed by 1 H nuclear magnetic resonance (NMR) spectroscopy over aging periods up to 28 days at intervals of 7 days, and the former also by microbiological analysis. The metabolome detected by 1 H NMR spectroscopy demonstrated changes over the aging time of beef and differed depending on the sampling location (surface or inner part of beef). The influence of the microbiota on changes in the metabolome can be negligible due to the low microbial growth on the surface of dry-aged beef (<3 log CFU/g). Therefore, the aging-related metabolism postmortem of the analyzed dry-aged beef might be the main factor for metabolic changes. The significantly (p < 0.05) higher amino acids and inosine concentrations and lower inosine 5'-monophosphate concentrations suggested enhanced protein degradation and energy metabolism in the wet-aged beef compared to the dry-aged beef, probably due to the combined influence of the aging and the microbiota on the wet-aged beef and, thus, its metabolic changes.

Trained sensory descriptors and volatile aroma compounds of USDA Select steaks using five grill temperatures

Thirty-three USDA Select boneless top loins were selected from carcasses at a commercial major packing plant, vacuum-packaged, and aged for 14 d (4 °C). The loins were then divided into 10 portions (5 grill temperatures for each of trained sensory panel and Warner-Bratzler shear force). Flat-top electric grills were pre-heated to 1 of 5 different temperatures: 149 °C (149), 177 °C (177), 204 °C (204), 232 °C (232), or 260 °C (260). Steaks were placed on the grill, turned when the internal temperature reached 35 °C and removed when the internal temperature reached 71 °C. A trained sensory panel evaluated ten basic flavors and five texture attributes. Extra cubes from each sample were frozen in liquid nitrogen and stored at -80 °C for GC/MS volatile aroma compound analysis. Beef identity, brown, and roasted flavor descriptors increased linearly (P < 0.001) while bloody/serumy tended to decrease (P = 0.016) and sour flavor decreased (P = 0.006) linearly as grill temperature increased. Furthermore, burnt (deviation P = 0.008) and bitter (deviation P = 0.012) flavor descriptors were affected by effects other than linear or quadratic, while umami (P = 0.002) and overall sweet (P = 0.016) flavors increased quadratically from 149 to 232 then declined at 260 grill temperatures. Two alcohols, eight aldehydes, four alkanes, three furans, eight ketones, and twelve pyrazines were impacted by differences the grill temperature. Increasing grill temperature increases volatile compounds, primarily from the Maillard reaction, that improve positive beef flavor descriptors.

Using untargeted metabolomics and volatile aroma compounds to predict expert sensory descriptors and consumer liking of beef loin steaks varying in quality grade, aging time, and degree of doneness

Precursors to flavor are important to its development, yet little is known about the intrinsic products of metabolism that influence flavor. Our objective was to use untargeted metabolomics and volatile aroma compounds to predict expert and consumer sensory traits. USDA Select and upper 2/3 Choice beef strip loins were wet aged for 10 or 20 d and then cut into steaks, vacuum-packaged, and frozen. Steaks were cooked to 63 °C, 71 °C, or 80 °C end-point internal steak temperature. USDA Choice steaks had more intense beef flavor identity, brown, roasted, fat-like, salty, sweet, sour, umami, buttery, and overall sweet flavors compared to USDA Select steaks (P < 0.05). Steaks cooked to 80 °C had more intense beef identity, brown, roasted, and umami flavors than steaks cooked to a lower degree of doneness. Steaks cooked to either 63 °C or 71 °C had more intense bloody, metallic, and sour flavors and were juicier, more tender, and had less connective tissue than steaks cooked to a higher degree of doneness. Volatile aroma compounds increased (P < 0.05) in Choice steaks aged for 20 d, while cooking steaks to 80 increased aldehydes, ketones, and pyrazines. Raw steaks had 69 small-molecule metabolomic compounds shared across all four quality grade x aging combinations, and discriminant analysis correctly categorized (P < 0.05) these metabolites. Metabolites and volatiles can be used to predict (r2 > 0.85) expert and consumer sensory panel descriptors and liking.

Molecular mechanisms contributing to the development of beef sensory texture and flavour traits and related biomarkers: Insights from early post-mortem muscle using label-free proteomics

Beef sensory quality comprises a suite of traits, each of which manifests its ultimate phenotype through interaction of muscle physiology with environment, both in vivo and post-mortem. Understanding variability in meat quality remains a persistent challenge, but omics studies to uncover biological connections between natural variability in proteome and phenotype could provide validation for exploratory studies and offer new insights. Multivariate analysis of proteome and meat quality data from Longissimus thoracis et lumborum muscle samples taken early post-mortem from 34 Limousin-sired bulls was conducted. Using for the first-time label-free shotgun proteomics combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS), 85 proteins were found to be related with tenderness, chewiness, stringiness and flavour sensory traits. The putative biomarkers were classified in five interconnected biological pathways; i) muscle contraction, ii) energy metabolism, iii) heat shock proteins, iv) oxidative stress, v) regulation of cellular processes and binding. Among the proteins, PHKA1 and STBD1 correlated with all four traits, as did the GO biological process 'generation of precursor metabolites and energy'. Optimal regression models explained a high level (58-71%) of phenotypic variability with proteomic data for each quality trait. The results of this study propose several regression equations and biomarkers to explain the variability of multiple beef eating quality traits. Thanks to annotation and network analyses, they further suggest protein interactions and mechanisms underpinning the physiological processes regulating these key quality traits. SIGNIFICANCE: The proteomic profiles of animals with divergent quality profiles have been compared in numerous studies; however, a wide range of phenotypic variation is required to better understand the mechanisms underpinning the complex biological pathways correlated with beef quality and protein interactions. We used multivariate regression analyses and bioinformatics to analyse shotgun proteomics data to decipher the molecular signatures involved in beef texture and flavour variations with a focus on multiple quality traits. We developed multiple regression equations to explain beef texture and flavour. Additionally, potential candidate biomarkers correlated with multiple beef quality traits are suggested, which could have utility as indicators of beef overall sensory quality. This study explained the biological process responsible for determining key quality traits such as tenderness, chewiness, stringiness, and flavour in beef, which will provide support for future beef proteomics studies.

Identification of SNPs Associated with Goose Meat Quality Traits Using a Genome-Wide Association Study Approach

(1) Background: Goose meat is highly valued for its economic significance and vast market potential due to its desirable qualities, including a rich nutritional profile, tender texture, relatively low-fat content, and high levels of beneficial unsaturated fatty acids. However, there is an urgent need to improve goose breeding by identifying molecular markers associated with meat quality. (2) Methods: We evaluated meat quality traits, such as meat color, shear force (SF), cooking loss rate (CLR), and crude fat content (CFC), in a population of 215 male Sichuan white geese at 70 days of age. A GWAS was performed to identify potential molecular markers associated with goose meat quality. Furthermore, the selected SNPs linked to meat quality traits were genotyped using the MALDI-TOP MS method. (3) Results: A dataset of 2601.19 Gb of WGS data was obtained from 215 individuals, with an average sequencing depth of 10.89×. The GWAS revealed the identification of 43 potentially significant SNP markers associated with meat quality traits in the Sichuan white goose population. Additionally, 28 genes were identified as important candidate genes for meat quality. The gene enrichment analysis indicated a substantial enrichment of genes within a 1Mb vicinity of SNPs in both the protein digestion and absorption pathway and the Glycerolipid metabolism pathway. (4) Conclusion: This study provides valuable insights into the genetic and molecular mechanisms underlying goose meat quality traits, offering crucial references for molecular breeding in this field.

Effects of dietary oat supplementation on carcass traits, muscle metabolites, amino acid profiles, and its association with meat quality of Small-tail Han sheep

Oat supplementation of the ruminant diet can improve growth performance and meat quality traits, but the role of muscle metabolites has not been evaluated. This study aimed to establish whether oat grass supplementation (OS) of Small-tail Han sheep improved growth performance and muscle tissue metabolites that are associated with better meat quality and flavor. After 90-day, OS fed sheep had higher live-weight and carcass-weight, and lower carcass fat. Muscle metabolomics analysis showed that OS fed sheep had higher levels of taurine, l-carnitine, inosine-5'-monophospgate, cholic acid, and taurocholic acid, which are primarily involved in taurine and hypotaurine metabolism, purine metabolism, and bile acid biosynthesis and secretion, decreased fat accumulation and they promote functional or flavor metabolites. OS also increased muscle levels of amino acids that are attributed to better quality and flavorsome mutton. These findings provided further evidence for supplementing sheep with oat grass to improve growth performance and meat quality.

Metabolome-Based Genome-Wide Association Study of Duck Meat Leads to Novel Genetic and Biochemical Insights

Meat is among the most consumed foods worldwide and has a unique flavor and high nutrient density in the human diet. However, the genetic and biochemical bases of meat nutrition and flavor are poorly understood. Here, 3431 metabolites and 702 volatiles in 423 skeletal muscle samples are profiled from a gradient consanguinity segregating population generated by Pekin duck × Liancheng duck crosses using metabolomic approaches. The authors identified 2862 metabolome-based genome-wide association studies (mGWAS) signals and 48 candidate genes potentially modulating metabolite and volatile levels, 79.2% of which are regulated by cis-regulatory elements. The level of plasmalogen is significantly associated with TMEM189 encoding plasmanylethanolamine desaturase 1. The levels of 2-pyrrolidone and glycerophospholipids are regulated by the gene expression of AOX1 and ACBD5, which further affects the levels of volatiles, 2-pyrrolidone and decanal, respectively. Genetic variations in GADL1 and CARNMT2 determine the levels of 49 metabolites including L-carnosine and anserine. This study provides novel insights into the genetic and biochemical basis of skeletal muscle metabolism and constitutes a valuable resource for the precise improvement of meat nutrition and flavor.

Mass spectrometry-based techniques for identification of compounds in milk and meat matrix

Food including milk and meat is often viewed as the mixture of different components such as fat, protein, carbohydrates, moisture and ash, which are estimated using well-established protocols and techniques. However, with the advent of metabolomics, low-molecular weight substances, also known as metabolites, have been recognized as one of the major factors influencing the production, quality and processing. Therefore, different separation and detection techniques have been developed for the rapid, robust and reproducible separation and identification of compounds for efficient control in milk and meat production and supply chain. Mass-spectrometry based techniques such as GC-MS and LC-MS and nuclear magnetic resonance spectroscopy techniques have been proven successful in the detailed food component analysis owing to their associated benefits. Different metabolites extraction protocols, derivatization, spectra generated, data processing followed by data interpretation are the major sequential steps for these analytical techniques. This chapter deals with not only the detailed discussion of these analytical techniques but also sheds light on various applications of these analytical techniques in milk and meat products.

New insights into the search of meat quality biomarkers assisted by Orbitrap Tribrid untargeted metabolite analysis and chemometrics

Metabolite profiles of normal and defective dry, firm and dark (DFD) meat extracts with known ultimate pH (pHu) values were determined by Orbitrap Tribrid ID-X untargeted analysis coupled to chemometrics. An intelligent MS³ AcquireX^TM workflow firstly approached the unambiguous characterization of detected features that were subsequently quantified by a complementary MS¹ study of biological replicates. Chemometric research revealed how threonylphenylalanine (overexpressed in normal meats) together to tetradecadienoyl- and hydroxydodecanoyl-carnitines (both overexpressed in DFD meats) appropriately grouped meat groups assayed. Robustness of such biomarkers was confirmed through a time-delayed study of a blind set of samples (unknown pHu) and evidenced limitations of pHu as an isolated parameter for accurate meat quality differentiation. Other acyl-carnitines also characterized DFD samples, suggesting interferences induced by pre-slaughter stress (PSS) on lipid catabolism that would explain accumulation of such intermediate metabolites. Results achieved can ease understanding of biochemical mechanisms underlying meat quality defects.

Molecular insights into quality and authentication of sheep meat from proteomics and metabolomics

Sheep meat (encompassing lamb, hogget and mutton) is an important source of animal protein in many countries, with a unique flavour and sensory profile compared to other red meats. Flavour, colour and texture are the key quality attributes contributing to consumer liking of sheep meat. Over the last decades, various factors from 'farm to fork', including production system (e.g., age, breed, feeding regimes, sex, pre-slaughter stress, and carcass suspension), post-mortem manipulation and processing (e.g., electrical stimulation, ageing, packaging types, and chilled and frozen storage) have been identified as influencing different aspects of sheep meat quality. However conventional meat-quality assessment tools are not able to elucidate the underlying mechanisms and pathways for quality variations. Advances in broad-based analytical techniques have offered opportunities to obtain deeper insights into the molecular changes of sheep meat which may become biomarkers for specific variations in quality traits and meat authenticity. This review provides an overview on how omics techniques, especially proteomics (including peptidomics) and metabolomics (including lipidomics and volatilomics) are applied to elucidate the variations in sheep meat quality, mainly in loin muscles, focusing on colour, texture and flavour, and as tools for authentication. SIGNIFICANCE: From this review, we observed that attempts have been made to utilise proteomics and metabolomics techniques on sheep meat products for elucidating pathways of quality variations due to various factors. For instance, the improvement of colour stability and tenderness could be associated with the changes to glycolysis, energy metabolism and endogenous antioxidant capacity. Several studies identify proteolysis as being important, but potentially conflicting for quality as the enhanced proteolysis improves tenderness and flavour, while reducing colour stability. The use of multiple analytical methods e.g., lipidomics, metabolomics, and volatilomics, detects a wider range of flavour precursors (including both water and lipid soluble compounds) that underlie the possible pathways for sheep meat flavour evolution. The technological advancement in omics (e.g., direct analysis-mass spectrometry) could make analysis of the proteins, lipids and metabolites in sheep meat routine, as well as enhance the confidence in quality determination and molecular-based assurance of meat authenticity.

Drivers of Palatability for Cats and Dogs-What It Means for Pet Food Development

The pet food industry is an important sector of the pet care market that is growing rapidly. Whilst the number of new and innovative products continues to rise, research and development to assess product performance follows traditional palatability methodology. Pet food palatability research focuses on the amount of food consumed through use of one-bowl and two-bowl testing, but little understanding is given to why differences are observed, particularly at a fundamental ingredient level. This review will highlight the key differences in feeding behaviour and nutritional requirements between dogs and cats. The dominant pet food formats currently available and the ingredients commonly included in pet foods are also described. The current methods used for assessing pet food palatability and their limitations are outlined. The opportunities to utilise modern analytical methods to identify complete foods that are more palatable and understand the nutritional factors responsible for driving intake are discussed.

Metabolomic profiling of postmortem aged muscle in Japanese Brown beef cattle revealed an interbreed difference from Japanese Black beef

OBJECTIVE

Japanese Brown (JBR) cattle, especially the Kochi (Tosa) pedigree (JBRT), is a local breed of moderately marbled beef. Despite the increasing demand, the interbreed differences in muscle metabolites from the highly marbled Japanese Black (JBL) beef remain poorly understood. We aimed to determine flavor-related metabolites and postmortem metabolisms characteristic to JBRT beef in comparison with JBL beef.

METHODS

Lean portions of the longissimus thoracis (loin) muscle from four JBRT cattle were collected at 0, 1, and 14 d postmortem. The muscle metabolomic profiles were analyzed using capillary electrophoresis time-of-flight mass spectrometry. The difference in postmortem metabolisms and aged muscle metabolites were analyzed by statistical and bioinformatic analyses between JBRT (n = 12) and JBL cattle (n = 6).

RESULTS

A total of 240 metabolite annotations were obtained from the detected signals of the JBRT muscle samples. Principal component analysis separated the beef samples into three different aging point groups. According to metabolite set enrichment analysis, postmortem metabolic changes were associated with the metabolism of pyrimidine, nicotinate and nicotinamide, purine, pyruvate, thiamine, amino sugar, and fatty acid; citric acid cycle; and pentose phosphate pathway as well as various amino acids and mitochondrial fatty acid metabolism. The aged JBRT beef showed higher ultimate pH and lower lactate content than aged JBL beef, suggesting the lower glycolytic activity in postmortem JBRT muscle. JBRT beef was distinguished from JBL beef by significantly different compounds, including choline, amino acids, uridine monophosphate, inosine 5'-monophosphate, fructose 1,6-diphosphate, and betaine, suggesting interbreed differences in the accumulation of nucleotide monophosphate, glutathione metabolism, and phospholipid metabolism.

CONCLUSION

Glycolysis, purine metabolism, fatty acid catabolism, and protein degradation were the most common pathways in beef during postmortem aging. The differentially expressed metabolites and the relevant metabolisms in JBRT beef may contribute to the development of a characteristic flavor.

Microbial spoilage mechanisms of vacuum-packed lamb meat: A review

Lamb meat is an important export commodity, however chilled vacuum-packed (VP) lamb has approximately half the shelf-life of beef under the same storage conditions. This makes the industry more vulnerable to financial losses due to long shipping times and unexpected spoilage. Understanding the spoilage mechanisms of chilled VP lamb in relation to VP beef is important for developing effective strategies to extend the shelf-life of lamb. This review has discussed various key factors (i.e., pH, fat, and presence of bone) that have effects on microbial spoilage of VP lamb contributing to its shorter shelf-life relative to VP beef. A range of bacterial organisms and their metabolisms in relevance to lamb spoilage are also discussed. The data gap in the literature regarding the potential mechanisms of spoilage in VP red meat is highlighted. This review has provided the current understanding of key factors affecting the shelf-life of VP lamb relative to VP beef. It has also identified key areas of research to further understand the spoilage mechanisms of VP lamb. These include investigating the potential influence of fat and bone (including bone marrow) on the shelf-life, as well as assessing changes in the meat metabolome as the spoilage microbial community is developing using an integrated approach. Such new knowledge would aid the development of effective approaches to extend the shelf-life of VP lamb.

- Invited Review - Postmortem skeletal muscle metabolism of farm animals approached with metabolomics

Skeletal muscle metabolism regulates homeostatic balance in animals. The metabolic impact persists even after farm animal skeletal muscle is converted to edible meat through postmortem rigor mortis and aging. Muscle metabolites resulting from animal growth and postmortem storage have a significant impact on meat quality, including flavor and color. Metabolomics studies of postmortem muscle aging have identified metabolisms that contain signatures inherent to muscle properties and the altered metabolites by physiological adaptation, with glycolysis as the pivotal metabolism in postmortem aging. Metabolomics has also played a role in mining relevant postmortem metabolisms and pathways, such as the citrate cycle and mitochondrial metabolism. This leads to a deeper understanding of the mechanisms underlying the generation of key compounds that are associated with meat quality. Genetic background, feeding strategy, and muscle type primarily determine skeletal muscle properties in live animals and affect post-mortem muscle metabolism. With comprehensive metabolite detection, metabolomics is also beneficial for exploring biomarker candidates that could be useful to monitor meat production and predict the quality traits. The present review focuses on advances in farm animal muscle metabolomics, especially postmortem muscle metabolism associated with genetic factors and muscle type.

Integrated Serum Metabolome and Gut Microbiome to Decipher Chicken Amino Acid Improvements Induced by Medium-Chain Monoglycerides

Chicken muscle yield and amino acid composition improvements with medium-chain monoglyceride (MG) supplementation were reported by previous studies, but the underlying mechanism was uncertain. This study aimed to decipher chicken amino acid improvements induced by medium-chain monoglycerides in the views of metabolomics, gene expression, and the gut microbiome. Newly hatched chicks (12,000 chicks) were weighed and randomly divided into two flocks, each with six replicates (1000 chicks per replicate), and fed a basal diet (the control group, CON) or a basal diet enriched with 300 mg/kg MG (the treated group, MG). Results demonstrated that MGs significantly increased the chicken flavor and essential and total amino acids. The serum amino acids and derivatives (betaine, l-leucine, l-glutamine, 1-methylhistide), as well as amino acid metabolism pathways in chickens, were enhanced by MG supplementation. Gene expression analysis exhibited that dietary MGs could improve muscle protein synthesis and cell growth via the mTOR/S6K1 pathway. Dietary MGs enhanced the cecal amino acid metabolism by selectively increasing the proportion of genera Lachnospiraceae_NK4A136_group and Bacteroides. Conclusively, the present study demonstrated that dietary MGs improved chicken amino acid composition via increasing both gut amino acid utilization and muscle amino acid deposition.

Metabolome and microbiome analysis revealed the effect mechanism of different feeding modes on the meat quality of Black Tibetan sheep

Introduction

Black Tibetan sheep is one of the primitive sheep breeds in China that is famous for its great eating quality and nutrient value but with little attention to the relationship between feeding regimes and rumen metabolome along with its impact on the muscle metabolism and meat quality.

Methods

This study applies metabolomics-based analyses of muscles and 16S rDNA-based sequencing of rumen fluid to examine how feeding regimes influence the composition of rumen microbiota, muscle metabolism and ultimately the quality of meat from Black Tibetan sheep. Twenty-seven rams were randomly assigned to either indoor feeding conditions (SG, n = 9), pasture grazing with indoor feeding conditions (BG, n = 9) or pasture grazing conditions (CG, n = 9) for 120 days.

Results

The results showed that, compared with BG and CG, SG improved the quality of Black Tibetan sheep mutton by preventing a decline in pH and increasing fat deposition to enhance the color, tenderness and water holding capacity (WHC) of the Longissimus lumborum (LL). Metabolomics and correlation analyses further indicated that the feeding regimes primarily altered amino acid, lipid and carbohydrate metabolism in muscles, thereby influencing the amino acid (AA) and fatty acid (FA) levels as well as the color, tenderness and WHC of the LL. Furthermore, SG increased the abundance of Christensenellaceae R-7 group, [Eubacterium] coprostanoligenes group, Methanobrevibacter, Ruminococcus 2 and Quinella, decreased the abundance of Lactobacillus, Prevotella 1 and Rikenellaceae RC9 gut group, and showed a tendency to decrease the abundance of Succinivibrio and Selenomonas 1. Interestingly, all of these microorganisms participated in the deposition of AAs and FAs and modified the levels of different metabolites involved in the regulation of meat quality (maltotriose, pyruvate, L-ascorbic acid, chenodeoxycholate, D-glucose 6-phosphate, glutathione, etc.).

Discussion

Overall, the results suggest that feeding Black Tibetan sheep indoors with composite forage diet was beneficial to improve the mouthfeel of meat, its color and its nutritional value by altering the abundance of rumen bacteria which influenced muscle metabolism.

Novel Insights into Total Flavonoids of Rhizoma Drynariae against Meat Quality Deterioration Caused by Dietary Aflatoxin B1 Exposure in Chickens

Aflatoxin B1 (AFB1) is a group of highly toxic mycotoxins that are commonly found in human and animal foods and threaten animal and human food safety. Total flavonoids of Rhizoma Drynaria (TFRD), a traditional Chinese medicinal herb, exert multiple biological activities such as immunomodulatory, anti-inflammatory, and anti-oxidation effects. Here, a total of 160 healthy 21-day-old male broilers were randomly divided into four groups: the CON group, the TFRD group, the AFB1 group, and the AFB1 + TFRD group. The study found that AFB1 exposure altered the breast meat quality-related indicators, including meat sensory and physical indicators. Metabolomics analysis further showed that the change in meat quality was closely associated with significantly differential metabolites of breast muscle. Furthermore, spotlighted amino acid content contributes to changes in the secondary structure of the myofibrillar protein by Raman spectroscopy analysis, which was associated with the oxidative stress and inflammatory response in AFB1-exposed breast meat. Meanwhile, dietary 125 mg/kg TFRD supplementation could effectively restore the changes in breast meat quality. Taken together, these results by multi-technical analysis revealed that AFB1 exposure causes deterioration of chicken meat quality and that TFRD may be a potential herbal extract to antagonize mycotoxicity.

Profiles of muscular amino acids, fatty acids, and metabolites in Shaziling pigs of different ages and relation to meat quality

Pork meat is closely related to physicochemical alterations during growth and development, resulting in differences in nutritional value and meat flavor. This study aimed to evaluate the composition of amino acids, fatty acids, and metabolic profiles in the longissimus thoracis muscle (LM) of Shaziling pigs aged 30, 90, 150, 210, and 300 days. The results showed that the predominant fatty acids identified in the LM of Shaziling pigs were C16:0, C16:1, C18:0, C18:1n9c, and C18:2n6c. An opposite correlation was observed for C18:2n6c and n6/n3 polyunsaturated fatty acids (P<0.05). Alanine, aspartate, glutamate, D-glutamine, and D-glutamate metabolism were the main metabolic pathways for the Shaziling pig meat flavor (P<0.05). Moreover, the correlation coefficients revealed that the contents of anserine, C16:0, C16:1, and C18:1n9c were positively correlated with intramuscular fat and/or pH_24h and were negatively correlated with the values of L* (lightness) and b* (yellowness) (P<0.05). In conclusion, age greatly affected the meat quality of Shaziling pigs, and the contents of muscular anserine, C16:0, C16:1, and C18:1n9c might be promising indicators for better meat quality.

Metabolomic Analysis of Wooden Breast Myopathy Shows a Disturbed Lipid Metabolism

Myopathies have risen strongly in recent years, likely linked to selection for appetite. For white striping (WS), causes have been identified; but for wooden breast (WB), the cause remains speculative. We used metabolomics to study the breast muscle of 51 birds that were scored for both at 35 days of age to better understand potential causes. A partial least square discriminant analysis revealed that WS and WB had distinct metabolic profiles, implying different etiologies. Arginine and proline metabolism were affected in both, although differently: WB increased arginine in breast muscle implying that the birds did not use this pathway to increase tissue blood flow. Antioxidant defenses were impeded as shown by low anserine and beta-alanine. In contrast, GSH and selenium concentrations were increased. Serine, linked to anti-inflammatory properties, was increased. Taurine, which can stabilize the cell's sarcolemma as well as modulate potassium channels and cellular calcium homeostasis, was also increased. Mineral data and depressed phosphatidylethanolamine, cAMP, and creatine-phosphate suggested compromised energy metabolism. WB also had drastically lower diet-derived lipids, suggesting compromised lipid digestion. In conclusion, WB may be caused by impaired lipid digestion triggered by a very high appetite: the ensuing deficiencies may well impair blood flow into muscle resulting in irreparable damage.

Comparative Characterization of Key Volatile Compounds in Slow- and Fast-Growing Duck Raw Meat Based on Widely Targeted Metabolomics

The volatile aroma compounds in raw duck meat strongly affect consumers' purchase decisions and they vary among breeds with different growth rates. In this study, slow-growing (SG) Liancheng White and fast-growing (FG) Cherry Valley ducks were selected, and their volatile compounds were characterized using electric nose and gas chromatography-mass spectrometry. Furthermore, a widely targeted metabolomics approach was used to investigate the metabolites associated with volatile compounds. The results showed that hexanal, nonanal, octanal, heptanal, and 2-pentylfuran were abundantly present in duck meat, regardless of the breed. The higher nonanal and octanal rates contributed to the fatty and fruity aroma in SG meat than FG meat, while FG meat had a mushroom note resulting from higher octenol. Furthermore, widely targeted metabolomics showed a lower carnitine content in SG meat, which might promote lipid deposition to produce more octanal and nonanal. Higher sugar and amino acid contents led to a meaty aroma, whereas more trimethylamine N-oxide may generate a fishy note in SG meat. Taken together, this study characterized the raw duck meat aroma and provided the basic mechanism of the formation of the key volatile compound.

Comparative Analysis of the Composition of Fatty Acids and Metabolites between Black Tibetan and Chaka Sheep on the Qinghai-Tibet Plateau

The objective of this study was to investigate and compare fatty acids and metabolites in the longissimus dorsi muscle between Black Tibetan and Chaka sheep grazing in a highly saline environment. A total of eight castrated sheep (14 months old) with similar body weights (25 ± 2.2 kg) were selected. The experimental treatments included Black Tibetan (BT) and Chaka sheep (CK) groups, and each group had four replications. The experiment lasted for 20 months. All sheep grazed in a highly saline environment for the whole experimental period and had free access to water. The results showed that the diameter (42.23 vs. 51.46 μm), perimeter (131.78 vs. 166.14 μm), and area of muscle fibers (1328.74 vs. 1998.64 μm2) were smaller in Chaka sheep than in Black Tibetan sheep. The ash content in the longissimus dorsi was lower in Chaka sheep than in Black Tibetan sheep (p = 0.010), and the contents of dry matter (DM), ether extract (EE), and crude protein (CP) in the longissimus dorsi showed no differences (p > 0.05). For fatty acids, the proportions of C10:0, C15:0, and tC18:1 in the longissimus dorsi were higher in Chaka sheep than in Black Tibetan sheep (p < 0.05). However, all other individual fatty acids were similar among treatments, including saturated fatty acids (SFAs), unsaturated fatty acids (UFAs), monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs), and the ratios of n-6 PUFAs to n-3 PUFAs and PUFAs to SFAs (p > 0.05). A total of 65 biomarkers were identified between the two breeds of sheep. Among these metabolites, 40 metabolic biomarkers were upregulated in the CK group compared to the BT group, and 25 metabolites were downregulated. The main metabolites include 30 organic acids, 9 amino acids, 5 peptides, 4 amides, 3 adenosines, 2 amines, and other compounds. Based on KEGG analysis, eight pathways, namely, fatty acid biosynthesis, purine metabolism, the biosynthesis of unsaturated fatty acids, renin secretion, the regulation of lipolysis in adipocytes, neuroactive ligand−receptor interaction, the cGMP-PKG signaling pathway, and the cAMP signaling pathway, were identified as significantly different pathways. According to the results on fatty acids and metabolites, upregulated organic acid and fatty acid biosynthesis increased the meat quality of Chaka sheep.

Untargeted metabolomics and proteomics approach using liquid chromatography-Orbitrap high resolution mass spectrometry to detect pork adulteration in Pangasius hypopthalmus meat

Pangasius hypopthalmus is well known as a good source of protein. However, Pangasius hypopthalmus meat (PHM) can be adulterated with pork for economic concern, thus, analytical methods for authentication are required. Untargeted metabolomics and proteomics using liquid chromatography-high resolution mass spectrometry (LC-HRMS) and chemometrics of principal component analysis (PCA) and partial least square-discriminant analysis (PLS-DA) was successfully used to differentiate authentic and adulterated PHM with the good of fitness (R > 0.95) and good of predictivity (Q > 0.5). Metabolites of PC(o-18:0/18:2(9Z,12Z)) was found to be a potential marker for pork whereas DMPC (dimyristoylphosphatidylcholine) was a potential marker for PHM. Meanwhile, pork peptide marker of myoglobin (HPGDFGADAQGAMSK) and β-hemoglobin (FFESFGDLSNADAVMGNPK) could be identified. Both metabolomics and proteomics using LC-HRMS could detect pork at the lowest concentration level (0.5% w/w). In conclusion, untargeted metabolomics and proteomics using LC-HRMS in combination with chemometrics could be used as powerful methods to detect pork adulteration in fish meat.

Application of Mass Spectrometry for Determining the Geographic Production Area of Wagyu Beef

Japanese Black cattle (Japanese Wagyu) beef is attracting attention for its aroma and marbling, and its handling is increasing worldwide. Here, we focused on the origin discrimination of Wagyu beef and analyzed the nutritional components of Japanese Wagyu (produced in multiple prefectures of Japan), Hybrid Wagyu (a cross between Angus and Wagyu cattle born in Australia and transported to Japan), and Australian Wagyu beef using mass spectrometry (MS). Triple-quadrupole liquid chromatography-MS was used to clarify the molecular species of lipids in Wagyu beef. Fourteen classes of lipids were separated, and 128 different triacylglycerides (TGs) were detected. A simple comparative analysis of these TGs using high-performance liquid chromatography revealed significantly higher levels of triolein (C18:1/C18:1/C18:1; abbreviated OOO) and C18:1/C18:1/C16:1 (OOPo) in Japanese Wagyu. Wagyu elements beef were comprehensively analyzed using inductively coupled plasma (ICP)-MS and ICP-optical emission spectrometry. We found significant differences in the rubidium, cesium, and lithium levels of Japanese and Australian Wagyu beef. On comparing metabolites using gas chromatography-MS, we identified significant differences in the levels of amino acids and other components of the Japanese and Australian Wagyu beef. These results suggest the possibility of determining the origin of Wagyu cattle breeds using MS and genetic discrimination.

The successful use of -omic technologies to achieve the 'One Health' concept in meat producing animals

Human health and wellbeing are closely linked to healthy domestic animals, a vital wildlife, and an intact ecosystem. This holistic concept is referred to as 'One Health'. In this review, we provide an overview of the potential and the challenges for the use of modern -omics technologies, especially transcriptomics and proteomics, to implement the 'One Health' idea for food-producing animals. These high-throughput studies offer opportunities to find new potential molecular biomarkers to monitor animal health, detect pharmacological interventions and evaluate the wellbeing of farm animals in modern intensive livestock systems.