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.

Oxidative stress has been suggested to negatively affect oocyte and embryo quality and developmental competence, resulting in failure to reach full term. In this study, we investigated the effect of N-acetyl-L-cysteine (NAC), a cell-permeating antioxidant, on developmental competence and the quality of oocytes and embryos upon supplementation (0.1–10 mM) in maturation and culture medium in vitro using slaughterhouse-derived oocytes and embryos. The results show that treating oocytes with 1.0 mM NAC for 8 h during in vitro maturation attenuated the intracellular reactive oxygen species (ROS) (p < 0.05) and upregulated intracellular glutathione levels (p < 0.01) in oocytes. Interestingly, we found that NAC affects early embryonic development, not only in a dose-dependent, but also in a stage-specific, manner. Significantly (p < 0.05) decreased cleavage rates (90.25% vs. 81.46%) were observed during the early stage (days 0–2), while significantly (p < 0.05) increased developmental rates (38.20% vs. 44.46%) were observed during the later stage (from day 3) of embryonic development. In particular, NAC supplementation decreased the proportion of apoptotic blastomeres significantly (p < 0.05), resulting in enhanced hatching capability and developmental rates during the in vitro culture of embryos. Taken together, our results suggest that NAC supplementation has beneficial effects on bovine oocytes and embryos through the prevention of apoptosis and the elimination of oxygen free radicals during maturation and culture in vitro.

Gut microbiota ferment non-digestible substances to produce metabolites that accumulate in muscle and influence host metabolism. However, the regulatory mechanisms connecting gut microbiota, metabolites, and fat deposition across pig breeds remain unclear. This study explores the gut–muscle axis regulating fat deposition and meat quality in Chinese Songliao Black Pig (SBP) and Large White × Landrace Pigs (LWLDP). Digesta samples from the ileum, cecum, and rectum of both breeds were analyzed using 16 S rRNA sequencing for microbiome profiling and ultra-high-performance liquid chromatography (UHPLC) for metabolomics. Multi-omics data, including microbiota and metabolite profiles were integrated with our previously published data of transcriptomics and metabolomics insights into fat deposition in the longissimus dorsi (LD) muscle using the MixOmics DIABLO method. Microbiome analysis revealed that Fibrobacter, Unidentified_Peptostreptococcaceae, Sutterella, and Unidentifed_Rickettsiales were enriched in SBP, while Ruminococcus, Corynebacterium, and Streptococcaceae in LWLDP. Metabolomic analysis indicated that SBP was enriched in fatty acid biosynthesis pathways, including linoleic acid, α-linolenic acid, and arachidonic acid, whereas LWLDP was associated with insulin signaling, starch and sucrose metabolism. Integrated analysis identified Peptostreptococcaceae and Rickettsiales in SBP, along with metabolites phosphatidylcholine (PC(22:4)), N-acylethanolamine (NAE(20:4)), and lysophosphatidylcholine (LysoPC(24:1)) were correlated with key genes (EIF4E, MSTN, PPARGC1A, NR4A3, and SOCS1) regulating fat deposition. In LWLDP, Corynebacterium and Streptococcaceae were linked to the PPP1R3B gene, which is involved in glycogen metabolism, as well as metabolites 2-methyl-3-hydroxybutyric acid and 5-keto-gluconic acid, suggesting a shift toward glycolysis over lipolysis. This study concluded that cecum-associated microbes in LWLDP may enhance carbohydrate metabolism, leading to reduced fat deposition, whereas rectum-associated microbes in SBP contribute to docosahexaenoic acid (DHA) biosynthesis, thereby improving meat quality. These findings highlight gut microbiota-derived metabolites as potential biomarkers for optimizing meat production and livestock breeding strategies.

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.

The vascular endothelium of xenografted pig organs represents the initial site of rejection after exposure to recipient immune cells. In this study, we aimed to develop a promoter specific to porcine vascular endothelial cells as a step toward overcoming xenograft rejection. Transcriptome analysis was performed on porcine aortic endothelial cells (PAECs), ear skin fibroblasts isolated from GGTA knockout (GTKO) pigs, and the porcine renal epithelial cell line pk-15. RNA sequencing confirmed 243 differentially expressed genes with expression changes of more than 10-fold among the three cell types. Employing the Human Protein Atlas database as a reference, we identified 34 genes exclusive to GTKO PAECs. The endothelial cell-specific adhesion molecule (ESAM) was selected via qPCR validation and showed high endothelial cell specificity and stable expression across tissues. We selected 1.0 kb upstream sequences of the translation start site of the gene as the promoter ESAM1.0. A luciferase assay revealed that ESAM1.0 promoter transcriptional activity was significant in PAECs, leading to a 2.8-fold higher level of expression than that of the porcine intercellular adhesion molecule 2 (ICAM2) promoter, which is frequently used to target endothelial cells in transgenic pigs. Consequently, ESAM1.0 will enable the generation of genetically modified pigs with endothelium-specific target genes to reduce xenograft rejection.

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.