The intuitive impression of pork is extremely important in terms of whether consumers are enthusiastic about purchasing it. Flesh color and intramuscular fat (IMF) are indispensable indicators in meat quality assessment. In this study, we determined the flesh color and intramuscular fat at 45 min and 12 h after slaughter (45 mFC, 45 mIMF, 12 hFC, and 12 hIMF) of 1518 commercial Duroc × Landrace × Large White (DLY) pigs. We performed a single nucleotide polymorphism (SNP) genome-wide association study (GWAS) analysis with 28,066 SNPs. This experiment found that the correlation between 45 mFC and 12 hFC was 0.343. The correlation between 45 mIMF and 12 hIMF was 0.238. The heritability of the traits 45 mFC, 12 hFC, 45 mIMF, and 12 hIMF was 0.112, 0.217, 0.139, and 0.178, respectively, and we identified seven SNPs for flesh color and three SNPs for IMF. Finally, several candidate genes regulating these four traits were identified. Three candidate genes related to flesh color were provided: SNCAIP and PRR16 on SSC2, ST3GAL4 on SSC5, and GALR1 on SSC1. A total of three candidate genes related to intramuscular fat were found, including ABLIM3 on SSC2, DPH5 on SSC4, and DOCK10 on SSC15. Furthermore, GO and KEGG analysis revealed that these genes are involved in the regulation of apoptosis and are implicated in functions such as pigmentation and skeletal muscle metabolism. This study applied GWAS to analyze the scoring results of flesh color and IMF in different time periods, and it further revealed the genetic structure of flesh color and IMF traits, which may provide important genetic loci for the subsequent improvement of pig meat quality traits.

Good skin quality not only improved carcass quality but also increased consumer demand for fresh poultry meat. This study aimed to investigate the developmental changes in skin growth and quality of Pekin ducks during 1-6 weeks of age. The skin samples were collected from the breast, back, and thigh tissues of six male ducks at the end of each week. The skin strength, skin thickness, and collagen content as well as the related gene expressions were determined for the evaluation of skin quality. The results showed that the body weight, absolute skin weight, areas, and density, epidermal and dermal thickness (breast and thigh), shearing force, piercing force (back and thigh), and collagen content in Pekin ducks increased linearly and quadratically with age, reaching a plateau at 5-6 weeks of age (P < 0.05). The mRNA expressions of IGF-1 and FGFR1 related to cell proliferation were highest in breast, back, and thigh of ducks at 3 weeks of age, while the mRNA expression of FGF14 and EGF associated with collagen synthesis reached maximum values at 5 weeks of age. Additionally, the mRNA expressions of IGF1R and FGFR2 were upregulated in breast and thigh skins of ducks at 1 week old and in back skin of ducks at 3 weeks old compared with birds at other weeks old (P < 0.05). In conclusion, the developmental pattern of skin growth and structure of Pekin ducks in a linear manner with increased age. The skin quality was increased in a quadratic manner, which was associated with the changes in mRNA expression of target genes related to cell proliferation and collagen synthesis.

The mechanistic underlying the favorable meat quality of Tibetan pigs has not been fully elucidated. This study integrated flavor chemistry, histomorphology, and proteomics to explore the structural and molecular features of their meat. Longissimus dorsi samples from Tibetan and Duroc pigs (n = 6 each biological replicates) were quantitatively analyzed for amino acid profiling, histological assessment, and proteomic characteristic. Statistical approaches included weighted correlation network analysis, t-tests, and functional enrichment. Tibetan pork contained 34 mg/100g more total free amino acids, notably sweet-tasting Ala (+49.2%) and Thr (+32.2%). Muscle fiber density was >250% higher and diameter > 30% smaller, indicating finer texture. Proteomics revealed 149 upregulated proteins, including 57 mitochondrial differentially expressed proteins (DEPs)—11 of which belonged to electron transport chain complexes (e.g., NDUFAB1, COX2). The significant enrichment of oxidative phosphorylation pathways may be associated with mitochondrial efficient energy metabolism under hypoxic in Tibetan pigs, potentially linking to the breed’s unique meat characteristics. Ala levels showed strong correlations with metabolic and structural protein modules. The finer fibers and mitochondrial protein profile of Tibetan pigs contribute to higher amino acid content and meat quality. This structural–metabolic–flavor axis supports both hypoxia adaptation and high meat quality. Given the central role of mitochondrial electron transport chain (ETC) proteins in energy metabolism and Ala in flavor presentation, their synergistic action provides a molecular bridge between hypoxia adaptation and meat quality. Therefore, this study suggests that ETC and Ala may serve as key biomarkers for meat quality differences, offering new perspectives for meat quality research.

Zinc, as a cofactor for various metalloenzymes in poultry, is essential for skin integrity, immune function, and wound healing. This study optimized the synthesis conditions of organic collagen peptide-chelated zinc (oZn) and evaluated their efficacy in improving skin quality using meat duck models. Firstly, the optimal synthesis conditions of oZn (collagen peptide was mixed with Zn sulfate) were then identified using an L16 (4^4) orthogonal design, with a peptide-to-Zn ratio of 4:1, pH 5, 60°C, and 10-minute. Then, either inorganic Zn (iZn) or oZn supplementation (60 mg/kg) increased growth performance, skin Zn content, quality (piercing force and shear force), dermal thickness, collagen content, and upregulated skin proliferation-related genes (ELN, MAP3K7, and P63) mRNA expression compared with without Zn addition (Con) using meat duck models (P < 0.05). Proteomic profiling revealed 134 (Con-iZn) and 174 (Con-oZn) differentially expressed proteins (DEP) in skin involved in chromatin remodeling (P = 0.01) and ribosomal biogenesis (P = 0.02). Notably, oZn displayed superior efficacy in dermal properties through elevated collagen biosynthesis than iZn. In conclusion, optimized collagen peptide-zinc chelate (pH 5, 60°C, 10 min, 4:1 ratio) improved growth performance and skin quality in meat ducks. Organic zinc demonstrating greater efficacy through enhanced collagen biosynthesis and dermal thickness. These findings establish a theoretical basis for developing novel Zn sources as nutritional strategies to optimize skin health in meat duck.