Background: The Qingyuan partridge chicken is a high-quality local chicken breed in China. Its weight gain directly affects breeding efficiency. This study used RNA sequencing to analyze gene expression dynamics in the breast muscle tissue of Qingyuan partridge chickens at 1, 35, 70, and 105 days of age. Methods: This study employed RNA-sequencing, integrated with differential expression analysis, weighted gene co-expression network analysis (WGCNA), and short time-series expression miner (STEM) analysis, to systematically investigate the transcriptomic dynamics in breast muscle tissue across four developmental stages. Results: Phenotypic analysis revealed a significant increase in both body weight (BW) and breast muscle weight with age (p < 0.05). Transcriptomic analysis identified 3521 genes specifically expressed at the age of one day compared with the other 3 ages. These were significantly enriched in pathways related to ribosomal biosynthesis, cytoskeletal regulation, and cell proliferation (p < 0.05). Turquoise and black modules were identified by WGCNA, containing 1563 hub genes, which significantly correlated with BW. Integration of differentially expressed genes and STEM analysis selected 26 BW-related key genes closely associated with muscle growth, including calmodulin 2 (CALM2), heat shock protein 90 alpha family class A member 1 (HSP90AA1), and cholinergic receptor nicotinic delta subunit (CHRND). Protein-protein interaction analysis revealed two functional networks centered around these genes. Enrichment analysis of the STEM profiles indicated that upregulated genes were significantly enriched in autophagy and the ErbB, FoxO, mTOR, and insulin signaling pathways, while genes related to the ribosome, cell cycle, and PPAR signaling pathways were downregulated. Conclusions: This study identified BW-related key genes and pathways, enriching our knowledge of the functional maintenance of chicken BW.

Inosine monophosphate (IMP) is a key umami-related nucleotide that contributes substantially to chicken meat flavor. This study aimed to elucidate the molecular regulatory mechanisms underlying individual variation in breast muscle IMP content in Beijing-You chicken through integrative transcriptomic and metabolomic analysis. A total of 73 male Beijing-You chickens at 135 days of age were phenotyped for IMP content in breast muscle. For extreme phenotype comparisons, 10 individuals with the highest IMP contents and 10 individuals with the lowest IMP contents were defined as the high-IMP and low-IMP groups, respectively. Transcriptomic and metabolomic datasets were generated from all 73 samples, and integrated using correlation analysis, Weighted Gene Co-expression Network Analysis (WGCNA), and machine learning models. Whereas extreme-group comparisons were used for PCA, differential analysis. IMP content showed moderate phenotypic variability within the population. Transcriptome analysis integrating elastic net regression, support vector machine (SVM) modeling, and differential expression analysis identified 22 high-confidence genes associated with IMP content, which were significantly enriched in various pathways, including purine metabolism, pyrimidine metabolism, and nicotinate and nicotinamide metabolism. Metabolomic integration combining WGCNA, differential analysis, and correlation analysis identified 14 key metabolites negatively correlated with IMP content, primarily enriched in purine metabolism, nucleotide metabolism, and the ABC transporter pathway. Integrated multi-omics analysis highlighted cytosolic 5 '-nucleotidase 1A-like (C5NT1AL), which was co-enriched with inosine, hypoxanthine, and guanosine within the purine metabolism pathway. These results suggest that C5NT1AL potentially regulates IMP deposition in chicken breast muscle through regulation of IMP dephosphorylation and downstream purine metabolic flux. This study identified C5NT1AL as a promising candidate gene influencing umami-related nucleotide metabolism and provides molecular insight into the genetic improvement of chicken meat flavor quality.

Meat color is an important economic trait of chicken that influences the willingness of consumers to buy it. Elucidating the genetic mechanisms regulating chicken color is essential to optimize poultry breeding strategies and improve meat quality. However, the genes and genetic variants involved remain unknown. In this study, the regulatory mechanism of the Jingxing yellow chicken color was revealed by a multi-omics approach, including transcriptomics/RNA sequencing (RNA-seq) analysis, comprehensive metabolomics analysis and carotenoid measurement. Our results showed that a significant region on chromosome 11 (15.36-15.47 Mb) was associated with the breast muscle meat color yellowness (b*), and BCO1 was mapped to this region as a candidate gene. In addition, the detection of the higher expression level of BCO1 mRNA in the group with the high-b* by RNA-seq analysis further supports that BCO1 is a key candidate gene associated with the breast muscle meat color b*. Also, the relevant single-nucleotide polymorphism (SNP) rs315311588 identified among the SNPs present in the 10 introns of BCO1, was found to reduce the expression level of BCO1 and increase the breast muscle meat color b*. Moreover, the multi-omics results reveal that decreased expression level of BCO1 leads to reduced conversion of lycopene to retinol, but significantly increases the content of lutein, which gives the yellow color to the breast muscle meat. Additionally, we also found that increase in yellow pigment production may promote fat deposition in breast muscle meat.

There are hundreds of local chicken breeds in China, which have a large consumer market due to their excellent flavor. In this study, Beijing You chicken and Wenchang chicken, were used to analyze the relationship between lipid and meat aroma through volatolomics and full-spectrum metabonomics. Multivariate statistical analysis identified 15 key meat aroma volatile organic compounds (VOCs) and their closely related metabolites, mainly including triglycerides (TGs), glycerophospholipids (GPs) and small peptides. Correlation network analysis of lipid metabolites revealed that GPs and TGs were highly positively correlated with unsaturated fatty acids, such as C20:5 and C16:1, which were involved in the formation of aldehydes. In chicken, phospholipid markers, mainly lysophosphatidylethanolamines and lysophosphatidylcholines, contributed significantly to the formation of meat flavor VOCs. Overall, this study revealed the relationship between different lipids and characteristic VOCs in chicken, providing a new understanding of the formation of VOCs and a theoretical basis for flavor regulation.

Growth traits are crucial for the economic viability in broiler production, as they significantly contribute to the cost of rearing. Maximizing body weight (BW) while minimizing feed intake is key to enhancing the efficiency of broiler breeding. Identifying the genetic architecture associated with BW trait is therefore a critical step in enhancing breeding strategies. We conducted a genome-wide association study (GWAS) using two statistical approaches: single-trait GWAS and longitudinal GWAS. The study was performed on the BW trait at five developmental stages (72, 81, 89, 113, and 120 days) and mid-test metabolic weight (MWT) across four growth cycles. Transcriptome sequencing analysis was also included to investigate the differential expression of candidate genes identified through the GWAS models, particularly linked to BW and MWT traits. Utilizing the chicken 55K single nucleotide polymorphism (SNP) array, we identified 52,060 SNPs in the genomic data of 4,493 Wenchang chickens. The single-trait GWAS model revealed 42 BW-associated SNPs, corresponding to 18 potential genes. For MWT, 47 SNPs were associated, mapping to 31 candidate genes. The longitudinal GWAS model identified 34 BW-linked SNPs, annotated with 22 candidate genes, and 21 MWT-linked SNPs, annotated with 10 candidate genes. Notably, 16 SNPs on chromosome 4 were associated with both BW and MWT, located within the 73.08Mb-76.82Mb region. Nine genes were annotated from this region, including STIM2, SEL1L3, SEPSECS, LGI2, SOD3, KCNIP4, NCAPG, FAM184B, LDB2. Notably, there are 32 overlapping SNPs identified in both the single-trait and longitudinal GWAS models, suggesting consistent associations for both BW and MWT. These overlapping SNPs represent robust loci that may influence both traits across different statistical approaches. Transcriptome sequencing indicated differential expression of LDB2 and SEL1L3 between high and low BW groups. Our study has uncovered novel candidate genes that are potentially involved in growth traits, providing valuable insights for broiler breeding. The identified SNPs and genes could serve as genetic markers for selecting broilers with improved growth efficiency, which may lead to more cost-effective and productive broiler farming.

AbstractAge has an important effect on the aroma of chicken meat. In this study, we systematically analyzed the patterns of aroma changes with increasing age and the key aroma‐contributing compounds and metabolites that lead to aroma differences with age. Electronic nose (e‐nose) and gas chromatography‐mass spectrometry analyses showed that the overall aroma intensity and the types and levels of volatile aroma compounds increased with age. Eight key aroma‐contributing compounds were identified by GC‐olfactometry (GC‐O) and odor activity value analyses, and their content increased with age. The e‐nose and GC‐O results revealed that 315‐day‐old chickens had the strongest aroma. Thus, taking 315‐day‐old chickens as reference, we found that the contents of key aroma‐contributing compounds and metabolites at 140 days of age were most similar to those at 315 days of age. Due to low feed cost, yellow chickens around 140 days of age were more suitable for marketing in terms of volatile aroma substances. It was found that hexanal, 1‐octen‐3‐ol, and (E,E)‐2,4‐decadienal contributed the most to chicken aroma. Additionally, small peptides were found to be the main types of metabolites responsible for the aroma difference in chickens due to age. Weighted gene co‐expression network analysis identified Ile‐Ser, Ile‐Thr, and Phe‐Ile as metabolic markers of hexanal and 1‐octen‐3‐ol, respectively. Further analysis revealed that Ile‐Ser, Ile‐Thr, and Phe‐Ile may promote the Maillard reaction by acting as substrates on the one hand, and facilitating the uptake of amino acids on the other hand, which in turn increases the contents of hexanal and 1‐octen‐3‐ol.

Hexanal contributes significantly to meat flavor. The aim of this study was to identify the metabolic pathways of hexanal formation in chicken meat. We found 32 metabolites associated with hexanal content in chicken meat, mainly including fatty acids (linoleic acid, etc., positive correlation) and some amino acids (L-proline, etc., negative correlation). A comparative analysis of the expression of these 32 metabolites between two groups of chickens with high- and low hexanal content revealed that L-proline and phenylacetaldehyde were downregulated, while ADP-ribose and 4-methylphenol were upregulated in the high-hexanal content chickens. It was also found that the increase of ADP-ribose induced the conversion of L-proline to other amino acids, such as arginine, through a process likely involving the pyrimidine metabolism pathway, leading to a reduction in proline content, which in turn abolished the inhibitory effect of proline on hexanal and enhanced the formation of hexanal. These findings confirm the effect of linoleic acid on hexanal content, and also reveal a negative regulatory effect of proline on the production of hexanal and its elimination mechanism in chicken meat.

Fatty acids (FAs) are one of the most important bioactive compounds affecting the quality of meat. In this study, we compared the expression profiles of genes involved in FA production in the breast muscle of Jingxing Yellow chickens at different days of age determined by transcriptomic analysis to identify key genes and pathways regulating the FA composition of the breast muscle. Through clustering analysis of gene expression data, the growth process of broiler chickens can be divided into two stages, namely the growth and development stage at the 35th and 63rd days of age (D35, D63), and the mature stage at the 119th day of age (D119). The content of some important unsaturated fatty acids (UFAs), such as C18:2n6c, C20:4n6, and C22:6n3, in the pectoral muscles, differed significantly between these two stages (p < 0.05). Therefore, we compared the gene expression profiles at D35 and D63 with those at D119, and identified differentially expressed genes (DEGs). The gene modules related to the five UFAs with significant changes were identified by weighted gene co-expression network analysis (WGCNA), and then 150 crossover genes were identified by crossover analysis of the detected DEGs and WGCNA. The results of the pathway enrichment analysis revealed the glycerolipid metabolism pathway related to lipid metabolism, in which the MGLL and LPIN1 genes were particularly enriched. In this study, the expression levels of MGLL and LPIN1 showed an increasing trend during the growth process of broilers, with a negative regulatory effect on the significantly reduced content of C18:2n6c in the pectoral muscle, and a positive regulatory effect on the significantly increased content of C20:4n6. These findings indicated that MGLL and LPIN1 synergistically promote the deposition of FAs, which may further promote the conversion of linoleic acid (C18:2n6c) to arachidonic acid (C20:4n6). Therefore, screening and identifying FA production-related functional genes are key to elucidate the regulatory molecular mechanism of production of FAs in chicken muscle, aiming to provide a theoretical basis for improving chicken meat quality.

Excessive abdominal fat deposition reduces the feed efficiency and increase the cost of production in broilers.Therefore,it is an important task for poultry breeders to breed broilers with low abdominal fat.Abdominal fat deposition is a highly complex biological process,and its molecular basis remains elusive.In this study,we performed transcriptome analysis to compare gene expression profiles at different stages of abdominal fat deposition to identify the key genes and pathways involved in abdominal fat accumulation.We found that abdominal fat weight(AFW)increased gradually from day 35(D35)to 91(D91),and then decreased at day 119(D119).Accordingly,after detecting differentially expressed genes(DEGs)by comparing gene expression profiles at D35 vs.D63 and D35 vs.D91,and identifying gene modules associated with fat deposition by weighted gene co-expression network analysis(WGCNA),we performed intersection analysis of the detected DEGs and WGCNA gene modules and identified 394 and 435 intersecting genes,respectively.The results of the Gene Ontology(GO)functional enrichment analysis and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway enrichment analyses showed that the steroid hormone biosynthesis and insulin signaling pathways were co-enriched in all intersecting genes,steroid hormones have been shown that regulated insulin signaling pathway,indicating the importance of the steroid hormone biosynthesis pathway in the development of broiler abdominal fat.We then identified 6 hub genes(ACTB,SOX9,RHOBTB2,PDLIM3,NEDD9,and DOCK4)related to abdominal fat deposition.Further analysis also revealed that there were direct interactions between 6 hub genes.SOX9 has been shown to bind to proteins required for steroid hormone receptor binding,and RHOBTB2 indirectly regulates the steroid hormones biosynthesis through cyclin factor,and ultimately affect fat deposition.Our results suggest that the genes RHOBTB2 and SOX9 play an important role in fat deposition in broilers,by regulating steroid hormone synthesis.These findings provide new targets and directions for further studies on the mechanisms of fat deposition in chicken.

Abstract Background Wenchang chickens are one of the most popular local chicken breeds in the Chinese chicken industry. However, the low feed conversion efficiency is the main shortcoming of this breed. Therefore, we urgently need to find a more precise breeding method to improve the feed efficiency of Wenchang chickens. In this study, we explored important candidate genes and variants for feed efficiency and growth traits by genome-wide association study (GWAS) analysis. Results Estimates of genomic heritability for growth and feed efficiency traits, including residual feed intake (RFI), average daily food intake (ADFI), average daily weight gain (ADG), body weight at 87, 95, 104, 113 days of age (BW87, BW95, BW104 and BW113), ranged from 0.05 to 0.44. Important candidate genes were screened related to feed efficiency and growth traits were screened, including PLCE1, LAP3, MED28, QDPR, LDB2 and SEL1L3 genes. Conclusion The results identified important candidate genes for feed efficiency and growth traits in Wenchang chickens and provide a theoretical basis for development of new molecular breeding technology.

Intramuscular fat (IMF) content is an important indicator of livestock and poultry meat quality. Enhancing IMF deposition can significantly improve meat quality. Focusing on the core process of IMF deposition, this study used the Jingxing Yellow (JXY) chickens as a model organism and employed multi-omics approaches, including RNA-sequencing (RNA-seq), Whole-genome bisulfite sequencing (WGBS), and metabolomics, to identify the key genes influencing IMF deposition in chickens during development. The results indicated that the contents of triglycerides (TG) and phospholipids (PLIP) exhibited an upward trend. The TG content did not differ significantly between day 1 (D1) and day 7 (D7), but increased significantly after 35 days (D35) of age. The WGBS results revealed that CpG methylation was the predominant methylation type in the breast muscle tissue of JXY chickens. Integrative analysis of RNA-seq and WGBS identified 50 genes, including PLA2G4F, PALMD, PLSCR5, ARHGEF26, LUM, DCN, TNRC6B, CACNA1C, ROBO1, and MBTPS2, whose methylation levels were significantly negatively correlated with their expression levels. In addition, the combined Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of differentially-expressed metabolites (DEM) and differentially-expressed genes (DEG) converged on the glycerophospholipid metabolism pathway, which was significantly enriched in DEGs such as PLA2G4F, PLA2G15, LPIN1, MBOAT2, DGKH, AGPAT2, and CHKA, as well as DEM like glycerophosphocholine and phosphocholine. Notably, PLA2G4F was identified as a DEG by DNA methylation, suggesting that PLA2G4F could be a key candidate gene influencing IMF deposition during chicken development. These findings are expected to provide a solid theoretical foundation for improving meat quality through targeted genetic and epigenetic interventions.

Fatty acids (FAs) can serve as energy for poultry, maintain normal cell structure and function, and support a healthy immune system. Although the addition of polyunsaturated fatty acids (PUFAs) to the diet has been extensively studied and reported, the mechanism of action of saturated fatty acids (SFAs) remains to be elucidated. We investigated the effect of 0.04% dietary myristic acid (MA) on slaughter performance, lipid components, tissue FAs, and the transcriptome profile in chickens. The results showed that dietary MA had no effect on slaughter performance (body weight, carcass weight, eviscerated weight, and pectoral muscle weight) (P P > 0.05). Dietary MA enrichment increased MA (P P < 0.001) and triglycerides (TGs) (P P < 0.01) levels in the pectoral muscle. The levels of palmitic acid, linoleic acid (LA), arachidonic acid (AA), SFAs, monounsaturated fatty acids (MUFAs), and PUFAs were significantly higher (P P < 0.01) in the MA supplementation group compared to the control group. However, there were no significant differences in the ratios of PUFA/ SFA and n6/omega-3 (n3) between the two groups. The MA content was positively correlated with the contents of palmitic acid, LA, linolenic acid (ALA), n3, n6, SFAs, and unsaturated fatty acids (UFA). DHCR24, , which is known to be involved in steroid metabolism and cholesterol biosynthesis pathways, was found to be a significantly lower in the MA supplementation group compared to the control group (P P < 0.05, log2(fold change) =-0.85). Five overlapping co-expressed genes were identified at the intersection between the differential expressed genes and Weighted Gene Co-expression Network Analysis- derived hub genes associated with MA phenotype, namely BHLHE40, MSL1, PLAGL1, SRSF4, , and ENSGALG00000026875. For the TG phenotype, a total of 28 genes were identified, including CHKA, KLF5, TGIF1, , etc. Both sets included the gene PLAGL1, , which has a negative correlation with the levels of MA and TG. This study provides valuable information to further understand the regulation of gene expression patterns by dietary supplementation with MA and examines at the molecular level the phenotypic changes induced by supplementation with MA.

Abdominal fat, which in the past was often regarded as waste and discarded, has in recent years been used as a fat source to produce meat by-products. Yellow abdominal fat has higher economic value. Therefore, improving the color of abdominal fat plays an important role in improving the appearance of meat products. This study aimed to identify the contributors and the regulatory network involved in the formation of yellow and white color in abdominal fat. We found that four xanthophyll compounds were significantly different in yellow and white abdominal fat chicken, including zeaxanthin, lutein, canthaxanthin, and β-cryptoxanthin. There were 551 different and 8 common metabolites significantly correlated with these 4 xanthophyll compounds. Similarly, a total of 54 common genes were identified in 4 common related pathways (Complement and coagulation cascades, Metabolic pathways, PPAR signaling pathway, Carbon metabolism) of the 8 common metabolites. The high expression of HAAO in the yellow abdominal fat group leads to the degradation of tryptophan and its intermediate 5-hydroxyindole, and subsequently to the formation of the four xanthophyll compounds. This process is also regulated by tyrosine, kynurenine 3-monooxygenase (KMO), homogentisate 1, 2-dioxygenase (HGD), etc. Together, these findings show the effect of tryptophan on abdominal fat color, as well as a negative regulatory effect of HAAO and 5-hydroxyindole on the production of xanthophyll compounds involved in abdominal fat coloration.

BACKGROUND:Wenchang chickens are one of the most popular local chicken breeds in the Chinese chicken industry. However, the low feed efficiency is the main shortcoming of this breed. Therefore, there is a need to find a more precise breeding method to improve the feed efficiency of Wenchang chickens. In this study, we explored important candidate genes and variants for feed efficiency and growth traits through genome-wide association study (GWAS) analysis. RESULTS:Estimates of genomic heritability for growth and feed efficiency traits, including residual feed intake (RFI) of 0.05, average daily food intake (ADFI) of 0.21, average daily weight gain (ADG) of 0.24, body weight (BW) at 87, 95, 104, 113 days of age (BW87, BW95, BW104 and BW113) ranged from 0.30 to 0.44. Important candidate genes related to feed efficiency and growth traits were identified, such as PLCE1, LAP3, MED28, QDPR, LDB2 and SEL1L3 genes. CONCLUSION:The results identified important candidate genes for feed efficiency and growth traits in Wenchang chickens and provide a theoretical basis for the development of new molecular breeding technology.

Background Intramuscular fat (IMF) is an important factor in meat quality, and triglyceride (TG) and Phospholipids (PLIP), as the main components of IMF, are of great significance to the improvement of meat quality. Results In this study, we used 30 RNA sequences generated from the transcriptome of chicken breast muscle tissues at different developmental stages to construct a gene expression matrix to map RNA sequence reads to the chicken genome and identify the transcript of origin. We used weighted gene co-expression network analysis (WGCNA) and identified 27 co-expression modules, 10 of which were related to TG and PLIP. We identified 150 highly-connected hub genes related to TG and PLIP, respectively, which were found to be mainly enriched in the adipocytokine signaling pathway, MAPK signaling pathway, mTOR signaling pathway, FoxO signaling pathway, and TGF-beta signaling pathway. Additionally, using the BioMart database, we identified 134 and 145 candidate genes related to fat development in the TG-related module and PLIP-related module, respectively. Among them, RPS6KB1, BRCA1, CDK1, RPS3, PPARGC1A, ACSL1, NDUFAB1, NDUFA9, ATP5B and PRKAG2 were identified as candidate genes related to fat development and highly-connected hub genes in the module, suggesting that these ten genes may be important candidate genes affecting IMF deposition. Conclusions RPS6KB1, BRCA1, CDK1, RPS3, PPARGC1A, ACSL1, NDUFAB1, NDUFA9, ATP5B and PRKAG2 may be important candidate genes affecting IMF deposition. The purpose of this study was to identify the co-expressed gene modules related to chicken IMF deposition using WGCNA and determine key genes related to IMF deposition, so as to lay a foundation for further research on the molecular regulation mechanism underlying chicken fat deposition.

Eggs are nutritious and highly valued by consumers. However, egg flavor varies greatly among different hen breeds. The present study used gas chromatography-olfactometry-mass spectrometry-based volatilomics to identify and compare volatile compounds in Taihe black-boned silky fowl (TS) and Hy-line Brown (HL) egg yolks. In addition, the relationships between the levels of different metabolites and lipids and flavor-associated differences were investigated using multiomics. Twenty-eight odorants in total were identified; among them, the levels of 3-methyl-butanal, 1-octen-3-ol, 2-pentylfuran, and (E, E)-2,4-decadienal differed significantly (P < 0.05) between TS and HL egg yolks. The difference in flavor compounds results in TS egg yolks having a stronger overall odor and flavor and a higher acceptance level than HL egg yolks. Metabolomic analysis revealed that 112 metabolites in the egg yolks were significantly different between the two breeds. Furthermore, these different metabolites in the egg yolks of both breeds were significantly enriched in phenylalanine, tyrosine, and tryptophan biosynthesis pathways and phenylalanine metabolism, alanine, aspartate, and glutamate metabolism pathways (P < 0.05), as identified by both metabolite set enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses. Lipidomic analysis revealed significant differences in the lipid subclasses, lipid molecules, and fatty acid profiles between the egg yolks from the two breeds. As a result, 48 lipid molecules had variable influence in projection values > 1 based on the partial least squares regression model, which may play a role in the differences in aroma characteristics between the two breeds through oxidative degradation of fatty acids. Our study revealed the metabolite, lipid, and volatility profiles of TS and HL egg yolks and may provide an important basis for improving egg flavor to satisfy various consumer preferences.

Aroma has an important influence on the aroma quality of chicken meat. This study aimed to identify the characteristic aroma substances in chicken meat and elucidate their metabolic mechanisms. Using gas chromatography-olfactometry and odor activity values, we identified nonanal, octanal, and dimethyl tetrasulfide as the basic characteristic aroma compounds in chicken meat, present in several breeds. Hexanal, 1-octen-3-ol, (E)-2-nonenal, heptanal, and (E,E)-2,4-decadienal were breed-specific aroma compounds found in native Chinese chickens but not in the meat of white-feathered broilers. Metabolomics analysis showed that L-glutamine was an important metabolic marker of nonanal, hexanal, heptanal, octanal, and 1-octen-3-ol. Exogenous supplementation experiments found that L-glutamine increased the content of D-glucosamine-6-P and induced the degradation of L-proline, L-arginine, and L-lysine to enhance the Maillard reaction and promote the formation of nonanal, hexanal, heptanal, octanal, and 1-octen-3-ol, thus improving the aroma profile of chicken meat.

Meat from different species has a unique odor; however, there is a lack of systematic research on the basic and characteristic components responsible for the formation of meat aroma. This study aimed to identify the con-tributors to meat odor by a multispecies comparison between chicken, duck, pork, and beef. The combined analysis identified 13 contributing substances. Eight substances [(E)-2-nonenal, (E,E)-2,4-decadienal, hexanal, heptanal, octanal, nonanal, 1-octen-3-ol, and dimethyl, tetrasulfide] were considered universal contributors to meat odor, and five [(E,E)-2,4-decadienal, (E,Z)-2,4-decadienal, (E,E)-2,4-nonadienal, (E)-2-nonenal, and (E)-2 -decenal] had a characteristic contribution to the aroma of meat from different species. Further, we revealed the positive relationship between 11 of these 13 substances. Also, arachidonic acid and diacylglycerol (16:0/16:0/ 0:0) were the metabolic markers of olefine aldehydes through five common pathways (biosynthesis of unsatu-rated fatty acids, and so on). These findings revealed the contributors and metabolic pathways to meat smell and might help understand the regulatory mechanism of the aroma quality of meat.

Alpha-linolenic acid (ALA, ω-3) is an antioxidant that reduces triglyceride (TG) levels in blood, a component of cell membranes and a precursor compound of eicosapentaenoic acid (EPA, ω-3) and eicosatrienoic acid (DHA, ω-3). Fatty acid content is a quantitative trait regulated by multiple genes, and the key genes regulating fatty acid metabolism have not been systematically identified. This study aims at investigating the protein-encoding genes regulating ω-3 polyunsaturated fatty acid (PUFA) content in chicken meat. We integrated genomics, transcriptomics and lipidomics data of Jingxing yellow chicken (JXY) to explore the interactions and associations among multiple genes involved in the regulation of fatty acid metabolism. Several key genes and pathways regulating ω-3 fatty acid metabolism in chickens were identified. The upregulation of GRB10 inhibited the mTOR signaling pathway, thereby improving the content of EPA and DHA. The downregulation of FGFR3 facilitated the conversion of ALA to EPA. Additionally, we analyzed the effects of ALA supplementation dose on glycerol esters (GLs), phospholipid (PL) and fatty acyl (FA) contents, as well as the regulatory mechanisms of nutritional responses in FFA metabolism. This study provides a basis for identifying genes and pathways that regulate the content of FFAs, and offers a reference for nutritional regulation systems in production.