Meat quality is a complex trait that exhibits significant variation across pig breeds, and the regulatory mechanisms governing pork meat quality are not fully elucidated. We compared the transcriptomics and metabolomics of the longissimus dorsi (LD) muscle between the Songliao Black Pig (SBP) and Large White × Landrace Pig (LWLDP) to investigate breed-specific differences in meat quality and underlying regulatory pathways. The results showed that SBP meat had a higher marbling score and backfat thickness, a richer color, a lower shear force, and reduced drip loss. Fatty acid (FA) analysis identified 15 significant FAs in the LWLDP, with docosahexaenoic acid (DHA) in the SBP, while amino acid (AA) analysis revealed no breed-based differences. Transcriptome analysis identified 134 upregulated and 362 downregulated genes in the SBP. Protein–protein interaction (PPI) network analysis found 25 key genes, which are associated with muscle development, fat deposition, and overall meat quality, while genes in the insulin signaling pathway, such as PPP1R3B, PPARGC1A, SOCS1, EIF4E, PRKAR2A, PRKAG2, and FASN, play a crucial role in balancing fat metabolism and catabolism. Metabolomic analysis identified 89 upregulated and 10 downregulated metabolites in the SBP, primarily involved in fructose and mannose metabolism, amino acid biosynthesis, nucleotide sugar metabolism, and glucagon signaling pathways. Gene–metabolite association analysis found that the PPP1R3B gene had a strong association with Thr-Leu, Maltol, D-myo-Inositol-4-phosphate, and Fructose-6-phosphate, while MYOG correlated with Mannose-6-phosphate, Fructose-1-phosphate, Mannose-1-phosphate, and Glucose-6-phosphate. In contrast, NR4A3 and PPARGC1A showed a strong negative correlation with most upregulated metabolites. In conclusion, this study identified functional genes, elucidated the mechanisms associated with meat quality traits, and identified gene–metabolite associations involved in energy metabolism, muscle development, and fat deposition, providing valuable insights into the molecular mechanisms that regulate meat quality between pig breeds.

Pork is one of the most widely consumed meats worldwide, with tenderness and intramuscular fat (IMF) content serving as key determinants of consumer acceptance. The rising demand for high-quality pork underscores the need to better understand the molecular mechanisms regulating IMF deposition and meat tenderness. In this study, we systematically examined the tenderness and IMF in the Longissimus dorsi (LD) muscle of 104 eight-month-old Songliao black pigs and Leixiang pigs raised under identical conditions. In addition, three pigs from each breed were randomly selected for multi-omics analyses, including Assay for Transposase-Accessible Chromatin sequencing (ATAC-seq), transcriptomics, and proteomics to elucidate the molecular networks underlying IMF deposition and tenderness. We identified a total of 2635 differentially accessible chromatin (DARs) regions associated with 2006 functional genes and 351 regulatory transcription factors, predominantly enriched in adipocyte differentiation and muscle metabolism pathways. Transcriptome analysis revealed 624 differentially expressed genes (DEGs) involved in lipid metabolism and tissue structure maintenance. While proteomic profiling detected 153 differentially expressed proteins (DEPs) enriched in fatty acid degradation/metabolism, PPAR signaling, energy metabolism, and thermogenesis pathways. Further, combined integrated multi-omics analysis identified nine candidate genes (MBP, DCLK1, COL3A1, ART3, COL14A1, PDK4, VCAN, LIPE, and GPX1) and transcription factor–target interaction networks predicted key regulatory factors including MEF2A/C/D, PR, GR, AR-HALLSITE, NF1-HALLSITE, AP4, TCF21, MYOG, ATOH1, TCF12, BHLHA15, MYF5, ASCL1, and SIX2, which were potentially involved in the regulation of meat tenderness and IMF deposition. These findings provide novel insights into the molecular determinants of IMF and tenderness, offering valuable targets for improving meat quality through genetic breeding strategies.

Histone deacetylase 9 (HDAC9) is a histone deacetylase (HDAC) subtype IIa protein that deacetylates histone 3 (H3), histone 4 (H4), and nonhistone proteins in vivo to alter chromosomal shape and regulate gene transcription. There have been few studies on the regulatory influence of the HDAC9 gene on the differentiation of chicken embryonic stem cells (cESCs) into male germ cells, and the significance of HDAC9 is still unknown. Therefore, we explored the specific role of HDAC9 during differentiation of the cESCs of Jilin Luhua chickens through inhibition or overexpression. In medium supplemented with 10^-5 mol/L retinoic acid (RA), cESCs were stimulated to develop into germ cells. HDAC9 and germline marker gene mRNA and protein levels were measured using qRT‒PCR and western blotting. During the differentiation of cESCs into male germ cells, overexpression of the HDAC9 gene greatly increased the mRNA and protein expression levels of the germline marker genes Stra8, Dazl, c-kit, and integrin ɑ6. The HDAC9 inhibitor TMP195 significantly decreased the mRNA and protein expression levels of the above markers. In summary, HDAC9 positively regulates the differentiation of cESCs.

Early testicular development is vital for adult male fertility but remains highly vulnerable to stress during the suckling stage. Fermented Chinese chive (Allium tuberosum) is known for its antioxidant and immunomodulatory properties, yet its role in testicular development remains unclear. In this study, Songliao Black piglets received 3‰ fermented Chinese chive (LK group) mixed with starter feed and compared to a control (OD group). Testicular samples at weaning (28 days) underwent transcriptomic and metabolomic analyses. Although no significant differences were observed in gross testicular morphology, the LK group significantly increased individual (13.85%) and litter (15.11%) weaning weights (p < 0.05), with elevated serum triglycerides, total cholesterol, and a 32.2% rise in IgG levels (p < 0.05). Integrated analysis identified 76 shared pathways, including ferroptosis, insulin resistance, PI3K-Akt, MAPK, and cAMP signaling. Upregulated genes in the LK group were mainly related to energy metabolism, antioxidant defense, immune regulation, steroidogenesis, and neuroendocrine signaling, suggesting improved metabolic activity, reduced oxidative stress, and accelerated reproductive maturation. Molecular docking indicated that kaempferol and isorhamnetin from Chinese chive bind strongly to proteins involved in testicular development. Overall, fermented Chinese chive supplementation enhances early testicular development in suckling piglets via integrated modulation of metabolic, immune, and signaling pathways, providing a nutritional strategy to optimize reproductive potential in breeding boars.

In this comparative study of 12 pigs (six Songlei black [SL] and six Duroc × Landrace × Yorkshire [DLY]), small RNA sequencing was performed on longissimus dorsi muscle samples to identify miRNAs associated with meat quality traits. A total of 343 known and 191 novel miRNAs were identified, including 21 differentially expressed miRNAs (DE-miRNAs) between breeds. Enrichment analysis showed that their target genes were enriched in the PI3K-Akt, MAPK, and calcium signaling pathways. Integration of miRNA and transcriptome datasets identified a regulatory network comprising five key miRNAs (ssc-miR-10383, ssc-miR-127, ssc-miR-370, ssc-miR-874, and a novel miRNA, novel_494) and 32 target genes annotated to autophagy, AMPK, mTOR, and FoxO signaling pathways. All five miRNAs were negatively correlated with IMF content (r = −0.77 to −0.95) and positively correlated with shear force (r = 0.62 to 0.76). This study provides the first miRNA expression profile of the longissimus dorsi muscle in SL and DLY pigs. These findings suggest that coordinated miRNA regulation may contribute to breed-specific differences in fat deposition and meat tenderness, providing candidate biomarkers for improving pork quality.

The study analyzed ten reproductive traits in three major commercial breeds—Yorkshire, Landrace, and Duroc—raised under uniform management. Genetic parameters were estimated using a repeatability animal model in ASReml, genome-wide association studies (GWAS) were performed with 46,358 post-QC SNPs using GCTA, and genomic prediction was evaluated with GBLUP. Heritability estimates were low to moderate, with gestation length (GL) highest (0.33–0.41). GWAS identified significant loci across breeds: in Yorkshire, 37 genome-wide significant SNPs across 17 SSCs for seven traits; in Landrace, 16 SNPs for TNB and one for NBW; and in Duroc, 31 SNPs across 12 SSCs (predominantly for TNB). Among these SNPs, CNC10042060, CNC10160995, and CNCB10003799 were consistently associated with TNB in both Yorkshire and Duroc pigs. Additionally, five SNPs, CNC10012965, CNC10042060, CNC10120451, CNCB10003799, and CNCB10007759, showed significant associations with NBW in Yorkshire and Landrace pigs. Candidate genes mapped within ±1 Mb of significant SNPs were enriched for biologically plausible pathways. Genomic prediction accuracies ranged from low to high depending on trait and breed, such as reaching 0.68 for GL in 39 Yorkshire and 0.59 in Landrace. These results delineate shared and breed-specific genetic architectures, provide actionable markers and candidate genes, and can accelerate genetic gains in commercial breeding programs.