In this study, we used young broilers to investigate the relationship between their gut microbiota and bursal B cell development. We characterized the important variables, microbes, B cells, and immunoglobulins during the posthatch development of birds.

Salmonella enterica is a food-borne pathogen that poses a severe threat to both poultry production and human health. Antibiotics are critical for the initial treatment of bacterial infections. However, the overuse and misuse of antibiotics results in the rapid evolution of antibiotic-resistant bacteria, and the discovery and development of new antibiotics are declining. Therefore, understanding antibiotic resistance mechanisms and developing novel control measures are essential. In the present study, GC-MS-based metabolomics analysis was performed to determine the metabolic profile of gentamicin sensitive (SE-S) and resistant (SE-R) S. enterica. Fructose was identified as a crucial biomarker. Further analysis demonstrated a global depressed central carbon metabolism and energy metabolism in SE-R. The decrease in the pyruvate cycle reduces the production of NADH and ATP, causing a decrease in membrane potential, which contributes to gentamicin resistance. Exogenous fructose potentiated the effectiveness of gentamicin in killing SE-R by promoting the pyruvate cycle, NADH, ATP and membrane potential, thereby increasing gentamicin intake. Further, fructose plus gentamicin improved the survival rate of chicken infected with gentamicin-resistant Salmonella in vivo. Given that metabolite structures are conserved across species, fructose identified from bacteria could be used as a biomarker for breeding disease-resistant phenotypes in chicken. Therefore, a novel strategy is proposed for fighting against antibiotic-resistant S. enterica, including exploring molecules suppressed by antibiotics and providing a new approach to find pathogen targets for disease resistance in chicken breeding.

This study explores the role of IgA‐coated bacteria in improving feed efficiency in chickens, offering a novel perspective for probiotic screening. Chickens with high feed efficiency were found to have a greater abundance of Gram‐positive bacteria, while low feed efficiency chickens exhibited higher levels of Gram‐negative bacteria and potential pathogens. Through fecal microbiota transplantation (FMT) and integrating analysis of cecal and IgA‐coated microbiota, we precisely identified Blautia as a key genus linked to improved feed efficiency. Further validation demonstrated that Blautia coccoides, a representative species of this genus, enhances feed efficiency and activates B cells to produce Immunoglobulin A (IgA), both in vivo and in vitro. Our findings provide new insights into the potential of IgA‐coated bacteria as functional probiotics, offering a promising strategy for enhancing feed efficiency in animal production.

The use of antibiotics leads to antibiotic residues in livestock and poultry products, adversely affecting human health. Ciprofloxacin (CFX) is a broad-spectrum antibiotic shared between animals and humans that is useful in treatments besides infections. However, changes in the gut microbiota caused by CFX and the possible link with the elimination of CFX residues have not been investigated. Herein, we used the Silkie chicken model to study the changes in the gut microbiota during the entire CFX-metabolic repertoire. We detected CFX residues in different tissues and showed that the elimination time of CFX from different tissues was dissimilar (liver > kidney > chest muscle > skin). Analysis of liver and kidney injury biomarkers and plasma antioxidant indices indicated slight hepatotoxicity and nephrotoxicity in the Silkie chickens. Importantly, the changes in the gut microbial community predominantly occurred early in the metabolic process. Correlation analysis revealed that the particular bacterial microbiota were associated with the pharmacokinetics of CFX in different Silkie chicken tissues (e.g., aerobic bacteria, including Escherichia and Coprococcus, and anaerobic bacteria, including Fusobacterium, Ruminococcus, Bifidobacterium, and Eubacterium). Collectively, certain microbiota may boost antibiotic metabolism and participate in restoring the microbial consortia after CFX is metabolized. Therefore, regulating the core intestinal microbiota may reduce foodborne antibiotics and accelerate the development of drug resistance.

Increasing studies show that gut microbiota play a central role in immunity, although the impact of the microbiota on mediation of thymic T cells throughout life is not well understood. Chickens have been shown to be a valuable model for studying basic immunology. Here, we show that changes in the gut microbiota are associated with the development of thymic T cells in young chickens. Our results showed that T-cell numbers in newborn chicks sharply increased from day 0 and peaked at day 49. Interestingly, the α-diversity score pattern of change in gut microbiota also increased after day 0 and continued to increase until day 49. We found that early antibiotic treatment resulted in a dramatic reduction in gut alpha diversity: principal component analysis (PCA) showed that antibiotic treatment resulted in a different cluster from the controls on days 9 and 49. In the antibiotic-treated chickens, we identified eight significantly different (p < 0.05) microbes at the phylum level and 14 significantly different (p < 0.05) microbes at the genus level, compared with the controls. Importantly, we found that antibiotic treatment led to a decreased percentage and number of T cells in the thymus when measured at days 9 and 49, as evaluated by flow cytometry. Collectively, our data suggest that intestinal microbiota may be involved in the regulation of T cells in birds, presenting the possibility that interventions that actively modify the gut microbiota in early life may accelerate the maturation of humoral immunity, with resulting anti-inflammatory effects against different pathogens.

The successful application of primordial germ cells (PGCs) is an ideal method for generating gene-edited birds. However, barriers to efficient DNA transfection in PGCs lead to low transfection efficiency, limiting the generation of genetically modified chickens. The current study utilized chemical transfection and electroporation methods to determine the optimal transfection conditions for the PGC line under feeder- and serum-free medium. Among the tested methods, the Lonza electroporation system exhibited the highest transduction efficiency, with a previously unreported rate of 71.13 ± 1.26%. Optimal transfection conditions were achieved using 4 µg of DNA and 100 µL of Entranster^TM-E in 1 × 10⁶ PGCs. Furthermore, the optimal electroporation conditions resulted in low cell death and normal expression of pluripotency-related genes, highlighting the low cytotoxicity. The resulting electroporation models were then used to deliver the enhanced green fluorescent protein (EGFP) gene to the Z chromosome with a Cas9-gRNA plasmid, achieving a 7-day insertion efficiency of 14.63 ± 1.07%. Our study highlights the vast potential of electroporation technology for the transfection of PGCs.