The microbiota of the female reproductive tract is increasingly recognized as playing fundamental roles in animal reproduction. To explore the relative contribution of reproductive tract microbiomes to egg production in chickens, we investigated the microbiota in multiple reproductive and digestive tract sites from 128 female layer (egg-producing) chickens in comparable environments. We identified substantial differences between the diversity, composition, and predicted function of site-associated microbiota. Differences in reproductive tract microbiota were more strongly associated with egg production than those in the digestive tract. We identified 4 reproductive tract microbial species, Bacteroides fragilis, Bacteroides salanitronis, Bacteroides barnesiae, and Clostridium leptum, that were related to immune function and potentially contribute to enhanced egg production. These findings provide insights into the diverse microbiota characteristics of reproductive and digestive tracts and may help in designing strategies for controlling and manipulating chicken reproductive tract microbiota to improve egg production.

The prelaying period is critical for laying hens, marked by significant physiological changes such as increased egg production, hormone secretion, and higher nutritional demands. These changes stress the intestine, which is vital for nutrient digestion, absorption, immune defense, and maintaining antioxidant and microbial balance. During this period, maintaining the intestinal health is essential for efficient nutrient absorption. Curcumin, a plant-derived extract, offers antioxidant, anti-inflammatory, antimicrobial, and immunomodulatory benefits, that can improve gut function. This study evaluated the effects of curcumin on the intestinal structure, immune barrier function, and cecal microbiota composition in laying hens during their early laying period. A total of 180 Snowy White chickens (154 days old) were divided into 5 experimental groups, receiving curcumin at 0 mg/kg, 100 mg/kg, 200 mg/kg, 300 mg/kg, and 400 mg/kg for 12 wk. The results showed that curcumin significantly improved the intestinal morphology (P < 0.05), increased mRNA expression of digestive enzymes (such as MGAM, SI, and ANPEP), and enhanced the digestive and absorptive functions. Further, curcumin improved the levels of antioxidant parameters (such as CAT, GSH-PX, T-AOC, and T-SOD) in the ileum, jejunum, and duodenum, and increased the expression of immunoglobulins (IgA, IgM, IgG) in the intestinal segments and serum (P < 0.05). Curcumin also improved the intestinal immune barrier function by increasing ZO-1 and Occludin expression. Furthermore, it altered the gut microbiota composition by increasing the relative abundance of beneficial bacterial phyla such as Bacteroidetes, Actinobacteria, Proteobacteria, and Fusobacteria (P < 0.05). At the genus level, curcumin supplementation enhanced the beneficial genera like Phocaeicola, Alistipes, Prevotella, Barnesiella, and Bifidobacterium (P < 0.05), thereby promoting the gut health and microbial diversity. In conclusion, curcumin supplementation during the early laying period of hens offers significant benefits by improving the intestinal health, immune function, and gut microbiota composition. Hence, curcumin serves as a promising dietary additive to support nutrient absorption and immune defense in laying hens during the early laying period of hens.

Maternal milk, a main source of nutrition for neonates in early life, has attracted attention. An increasing number of studies have found that maternal milk has a high microbial diversity, as well as factors that might influence this diversity. However, there is a lack of knowledge regarding the effects of host diet and phylogeny on maternal milk microbes and the contribution of the maternal milk microbiota to the neonatal gut microbiota. Here, we analyzed the maternal milk and fecal microbiota of nine species (lion, dog, panda, human, mouse, rhesus macaque, cow, goat, and rabbit) of mammals of three type groups (herbivore, omnivore, and carnivore) using 16S rRNA amplicon sequencing. Our study provided evidence of host diet and phylogeny on the maternal milk microbiota. Moreover, functional prediction revealed that the carnivores had a significantly higher percentage of base excision repair, glycerolipid metabolism, taurine and hypotaurine metabolism, inorganic ion transport and metabolism, and nucleotide metabolism; while arginine and proline metabolism showed enrichment in the herbivore group. Source-tracking analysis showed that the contributions of bacteria from maternal milk to the microbiota of neonates of different mammals were different at day 3 after neonatal birth. Overall, our findings provided a theoretical basis for the maternal milk microbiota to affect neonatal fecal microbiota at day 3 after neonatal birth.

Liver development is a complex process that is regulated by a series of signaling pathways. Three-dimensional (3D) chromatin architecture plays an important role in transcriptional regulation; nonetheless, its dynamics and role in the rapid transition of core liver functions during development and obesity-induced metabolic stress remain largely unexplored. To investigate the dynamic chromatin architecture during liver development and under metabolic stress, we generated high-resolution maps of chromatin architecture for porcine livers across six major developmental stages (from embryonic day 38 to the adult stage) and under a high-fat diet-induced obesity. The characteristically loose chromatin architecture supports a highly plastic genome organization during early liver development, which fundamentally contributes to the rapid functional transitions in the liver after birth. We reveal the multi-scale reorganization of chromatin architecture and its influence on transcriptional regulation of critical signaling processes during liver development, and show its close association with transition in hepatic functions (i.e., from hematopoiesis in the fetus to metabolism and immunity after birth). The limited changes in chromatin structure help explain the observed metabolic adaptation to excessive energy intake in pigs. These results provide a global overview of chromatin architecture dynamics associated with the transition of physiological liver functions between prenatal development and postnatal maturation, and a foundational resource that allows for future in-depth functional characterization.

The reproductive tract of chickens is an important organ for egg formation. The vagina is in close contact with the external environment, which may lead to the invasion of a variety of pathogenic bacteria, affect the internal and external quality of eggs, and even increase mortality and cause economic loss. In recent years, probiotics as a substitute for antibiotics have brought economic benefits in livestock and poultry production. In the present study, we investigated the effects of vaginal administration of Bacteroides fragilis on the cloacal microbiota, vaginal transcriptome and metabolomics of chickens and evaluated the beneficial potential of B. fragilis. The results showed that B. fragilis treatment could affect the microbial composition of the cloaca. Transcriptome analysis found that the immune-related genes CCN3, HAS2, and RICTOR were upregulated, that the inflammatory genes EDNRB, TOX, and NKX2-3 were downregulated, and that DEGs were also enriched in the regulation of the inflammatory response, cellular metabolism, and synaptic response pathways. In addition, the differential metabolites were mainly related to steroid hormone biosynthesis, unsaturated fatty acid biosynthesis, and arachidonic acid metabolism, and we identified associations between specific differential metabolites and genes. Overall, this study provides a theoretical basis for the application of B. fragilis as a potential probiotic in livestock and poultry production.

Background: The Tibetan chicken has adapted well to high altitudes genetically after its long-term habitation in the plateau. In this study, we analyzed the selection signal of Tibetan black chickens (TBCs) and discovered genes associated with the characteristics of germplasm. Methods: Whole-genome sequencing (WGS) was used to identify the single-nucleotide polymorphism (SNP) markers and genetic structures in the genome of Tibetan black chickens. Further, we performed a comparative population genomics analysis between the genomic data obtained in this present study and the genomic data for five wild red jungle fowls (RJFs) accessed from the NCBI database (GenBank accession number PRJNA241474). Thereafter, the Fst and Pi selections were used to identify genes under positive selection in the Tibetan black chicken genome. Results: A total of 9,490,690 SNPs were identified in the Tibetan black chickens. In addition, the results from the gene ontology (GO) analysis showed that 732 genes of TBCs were enriched in a total of 210 GO terms with specific molecular functions such as regulation of cellular catabolic process, the MAPK signaling pathway, regulation of ion transport, growth, morphogenesis and lung alveolus development which may provide a better mechanism to facilitate oxygen transport and utilization in TBCs. Moreover, the results from the KEGG analysis showed that 732 genes of the TBCs were significantly enriched in the calcium signaling pathway, circadian entrainment (ADCY1, GNG7 and PER3), oxytocin signaling pathway and pathways of multiple neurodegeneration diseases. In addition, the CD86 antigen (CD86) was identified as a gene associated with the immune response in chickens. It was also revealed that genes such as TRIT1, HPCAL4, NT5C1A and HEYL were discovered under selection in Tibetan black chickens on chromosome 23. These genes may be related to the local adaptive characteristics of Tibetan black chickens, for instance, NT5C1A and HEYL may be involved in the high-altitude adaption of oxygen delivery in Tibetan black chickens. Conclusions: In summary, we found that selection mainly affects the disease resistance and cold acclimatization of Tibetan black chickens. Hence, these results may provide important genetic information for the evolution and breeding of Tibetan black chickens.