Background: Antibiotic resistance has intensified the search for alternatives in poultry production. Essential oils (EOs), particularly blends of carvacrol and thymol, have shown potential as natural growth promoters and antimicrobials. This study evaluated a composite carvacrol-thymol EO as an antibiotic substitute in broiler production, focusing on growth performance, serum biochemistry, intestinal morphology, and gut microbiota. Materials and methods: A total of 672 Aibayi-Yijia broilers were randomly assigned to seven treatment groups: control (CK), EO1 (200 g/t feed), EO2 (600 g/t feed), EO3 (1200 g/t feed), EO1+AG (EO 200 g/t + FON 0.15 g/kg feed), EO3+AG (EO 1200 g/t + FON 0.15 g/kg feed), and AG (FON 0.15 g/kg feed). Growth performance, serum biochemistry (TP, ALB, GLB, GLU, AST, GGT, CHOL, TG, IL), jejunal histology (villus height, crypt depth, V:C ratio), and cecal microbiota (16S rRNA sequencing) were assessed. Results: Supplementation with EO (600 g/t) or florfenicol followed by 1200 g/t EO significantly increased ABW and ADFI ( p < 0.05). EO (200 g/t or 1200 g/t) supplementation after antibiotics reduced serum TP, ALB, GLB, and CHOL ( p < 0.05). Histological analysis showed increased villus height and V:C ratios with 1200 g/t EO. Cecal microbiota shifted, with increased Bacteroidetes and decreased Firmicutes. Discussion: The composite carvacrol-thymol EO blend showed promise as an antibiotic alternative, improving growth performance, supporting intestinal health, and modulating the gut microbiota. Further research is needed to optimize dosing, assess long-term safety, and explore EO interactions for scalable use.

For the protection of Protected Geographical Indication (PGI) Sunite lamb, PGI Sunite lamb samples and lamb samples from two other banners in the Inner Mongolia autonomous region were distinguished by stable isotopes (δ¹³C, δ¹⁵N, δ²H, and δ¹⁸O) and two local modeling approaches. In terms of the main characteristics and predictive performance, local modeling was better than global modeling. The accuracies of five local models (LDA, RF, SVM, BPNN, and KNN) obtained by the Adaptive Kennard–Stone algorithm were 91.30%, 95.65%, 91.30%, 100%, and 91.30%, respectively. The accuracies of the five local models obtained by an approach of PCA–Full distance based on DD–SIMCA were 91.30%, 91.30%, 91.30%, 100%, and 95.65%, respectively. The accuracies of the five global models were 91.30%, 91.30%, 91.30%, 100%, and 91.30%, respectively. Stable isotope ratio analysis combined with local modeling can be used as an effective indicator for protecting PGI Sunite lamb.

Background: Fermented meat products rely on complex microbial interactions to develop desirable safety, nutritional and sensory attributes. Lactic acid bacteria and yeasts are among the most frequently used starter cultures, yet their individual and interactive contributions to physicochemical changes and metabolite formation remain incompletely understood. In particular, how different inoculation ratios of bacteria and yeast regulate acidification, nitrogen metabolism and lipid remodeling in fermented meat has received limited attention. Therefore, this study investigated the effects of single and co-fermentation by Lactobacillus plantarum and Debaryomyces hansenii at different inoculation ratios on physicochemical properties and the non-volatile metabolome of fermented meat. Methods: Six fermentation treatments were designed, including an uninoculated control (A), L. plantarum alone (B), D. hansenii alone (C), and co-inoculated systems with lactic acid bacteria to yeast ratios of 1:1 (D), 1:2 yeast-dominant (E), and 2:1 lactic acid bacteria-dominant (F). After fermentation, pH, protein content and total volatile basic nitrogen (TVB-N) were determined to evaluate acidification, protein accumulation and nitrogen degradation. Untargeted non-volatile metabolomics was performed, and differential metabolites among treatments were screened using orthogonal partial least squares discriminant analysis (OPLS-DA). Results: Compared with the control (pH 6.01, protein 17.6 g per 100 g, TVB-N 8.4 mg per 100 g), L. plantarum fermentation markedly lowered pH to 4.72 and reduced TVB-N to 7.3 mg per 100 g. D. hansenii alone caused moderate acidification (pH 5.77), increased protein content to 21.9 g per 100 g, and resulted in a TVB-N level of 7.6 mg per 100 g. Co-fermentation showed clear ratio-dependent effects. Treatments D and F achieved lower pH values (4.55 and 4.45) with TVB-N levels of 6.2 and 5.6 mg per 100 g, respectively. The yeast-dominant treatment E exhibited the highest protein content (24.7 g per 100 g) and the lowest TVB-N (4.3 mg per 100 g). Metabolomics analysis identified 72 differential non-volatile metabolites, mainly lipids and nitrogen-containing compounds. Treatment E was characterized by increased free amino acids, phospholipids (e.g., LPC 18:2 and LPE 18:2), unsaturated fatty acids (linoleic and oleic acids), and nicotinic acid, whereas treatment F showed intensified phospholipid signals (e.g., PC 34:1) accompanied by depletion of multiple amino acids and nicotinamide. Discussion: The results demonstrate that the inoculation ratio of L. plantarum and D. hansenii plays a decisive role in regulating acidification, proteolysis and lipid remodeling during meat fermentation. Yeast-dominant co-fermentation promoted protein accumulation and enrichment of unsaturated fatty acids, likely through enhanced proteolytic activity and lipid metabolism, while effectively limiting TVB-N formation. In contrast, lactic acid bacteria-dominant fermentation intensified acidification and further suppressed nitrogenous spoilage indicators, albeit with reduced amino acid availability. These findings highlight the importance of microbial balance in starter culture design and provide a mechanistic basis for tailoring fermentation strategies to simultaneously improve safety and sensory quality of fermented meat products.

Pingliang Red Cattle, a renowned geographical indication product in China, is distinguished by its superior meat quality, yet the scientific basis for its unique attributes remains underexplored. This study integrated metabolomic and transcriptomic analyses to elucidate the biochemical and physiological factors underlying the enhanced flavor, color stability, and tenderness of Pingliang Red Cattle beef compared to Qinchuan and Simmental cattle. Metabolomic profiling revealed significantly elevated levels of inosine monophosphate (IMP, 2.86–3.96× higher) and glutathione (GSH, 2.42–5.43× higher) in Pingliang Red Cattle, contributing to intense umami flavor and prolonged meat color retention. Notably, ergothioneine (EGT), a potent antioxidant, was identified for the first time in Pingliang Red Cattle beef, with concentrations 2.55× and 4.25× higher than in Qinchuan and Simmental, respectively. Transcriptomic analysis highlighted the upregulation of 21 tenderness-related genes (e.g., FABP3, PRDX6, CAST) and key enzymes in purine and glutathione metabolism pathways (e.g., PDE4D, ADSL, GGT1), correlating with meat tenderness and the improved meat quality. Additionally, Pingliang Red Cattle’s natural forage-rich diet and low-density rearing practices were critical in enhancing these traits. These findings provide a scientific foundation for Pingliang Red Cattle’s premium quality, offering actionable insights for GI product branding, quality optimization, and market competitiveness. The multi-omics approach established here serves as a paradigm for quality assessment and improvement of other GI agricultural products, bridging traditional reputation with molecular evidence.