理学最新文献

Background: The crop is a unique anterior digestive organ in poultry that functions in temporary feed storage and lactic acid bacteria-dominated fermentation, thereby interacting with the gastrointestinal tract to influence gut health and feed efficiency. However, its developmental characteristics and functional establishment across the entire growth cycle remain poorly understood.

Results: A slow-growing chicken breed (Lueyang Black-boned chicken) was used to characterize dynamic changes in crop histomorphology, mucosal immune status, and microbiota from hatch to adulthood (d 1, 14, 28, 42, 56, 70, 98, and 140; n = 10 per time point). Crop development was divided into two stages. From d 1 to d 42, the crop underwent structural and microbial establishment. This stage was characterized by a slow increase in crop weight, progressive thickening and stabilization of the muscular and mucosal layers, and a gradual increase in secretory immunoglobulin A (sIgA) levels. Genes involved in mucin synthesis and modification were markedly upregulated during early development (d 1 to d 14). Meanwhile, the microbiota shifted from environmentally associated facultative anaerobes to lactic acid bacteria-dominated communities (Lactobacillus, Ligilactobacillus, and unclassified Bacilli). Correspondingly, predicted microbial functions shifted from colonization-related pathways to carbohydrate, fatty acid, and butyrate metabolism. From d 42 to d 140, the crop entered a stage of structural expansion and microbial restructuring. Crop weight increased rapidly, and the mucosal layer exhibited fluctuations, while sIgA levels continued to increase and stabilized. During d 42 to d 56, fluctuations in mucosal thickness were accompanied by reduced mucin sialylation. At the same time, lactic acid bacteria populations shifted, with a decrease in Ligilactobacillus and an increase in unclassified Bacilli, followed by stabilization of the microbial community. Functional prediction indicated enrichment of membrane transport systems and diverse nutrient metabolism pathways.

Conclusion: This study demonstrates that the early post-hatch period establishes the crop's basic functions, whereas the growing period is characterized by crop expansion and further maturation of the microbial community. These findings provide a theoretical basis for targeted interventions in the crop to improve poultry production performance.

Amino acids available for bacteria within the small intestine of pigs are originating mainly from the dietary and endogenous proteins. These amino acids, in addition to those synthesized by the intestinal bacteria, are used in different metabolic pathways. The amino acids that cannot be synthesized by the intestinal bacteria can be considered as indispensable for them and must thus be obtained from the surrounding luminal fluid. In the pig large intestine, the amino acids used by bacteria originate presumably mainly from proteins not fully digested in the small intestine. In this narrative review, we present the current knowledge concerning the metabolism of amino acids by bacteria found in the pig gut and the effects of the different amino acid-derived bacterial metabolites on the metabolism and physiology of the intestinal microbes. The effects of some among these compounds, either beneficial or deleterious, on the intestinal epithelial cells are then recapitulated. Next, the adverse impact of the emission of two bacterial metabolites derived from amino acids, namely ammonia and hydrogen sulfide, on the environment is described. Future directions in the field of the control of the metabolism of amino acids by the intestinal bacteria for the maintenance of pig intestinal health, as well as for the reduction of the emission of polluting substances are proposed.

Background: Deoxynivalenol (DON), a mycotoxin commonly found in grains and feed, poses a serious threat to animal and public health. This study aimed to investigate the underlying mechanisms of DON-induced liver damage in piglets and to elucidate the potential of alginate-encapsulated enzyme in mitigating hepatotoxicity in vivo.

Results: The results indicated that DON exposure induced growth retardation and hepatic mitochondrial damage in piglets, which were effectively rescued by DON-degrading enzymes (DDE) supplementation. Hepatic transcriptomic profiling revealed that DON induced downregulation of oxidative phosphorylation‑related genes and ATP-binding cassette subfamily B member 4 (ABCB4), accompanied by the upregulation of the chemokine CCL21 and the adhesion molecule VCAM1. In contrast, no downregulation of oxidative phosphorylation‑related genes or aberrant expression of the aforementioned factors was observed in the DDE treatment group. Meanwhile, DON promotes T cell recruitment and their differentiation into the pro-inflammatory Th17 subset by inducing NF-κB-mediated expression of IL-1β and CCL21, thereby amplifying the inflammatory response. Further analysis revealed that DON exposure induced metabolic dysfunction of lysophospholipids and glycolithocholic acid (GLCA) in the liver and suppressed farnesoid X receptor (FXR) expression. Mechanistically, the downregulation of ABCB4 by DON was associated with reduced expression of PPARγ coactivator-1α (PGC-1α) and FXR, suggesting a potential link involving the PGC-1α/FXR axis. This downregulation results in the accumulation of GLCA, thereby exacerbating hepatic damage. Notably, alginate-encapsulated DDE effectively reversed the DON-induced GLCA metabolic dysfunction and the Th17 immune response.

Conclusions: Alginate-encapsulated DDE effectively mitigated DON-induced hepatic mitochondrial damage, T cell enrichment, and impaired bile acid metabolism in piglets. This study suggests a potential ABCB4‑dependent mechanism underlying DON-induced hepatotoxicity and provides a promising enzymatic strategy for mitigating DON contamination in vivo. However, further studies are required to clarify the potential mechanism of DON-induced hepatotoxicity.

Background: Diarrhea in suckling lambs is associated with gut microbiota dysbiosis, impaired intestinal barrier function, and enhanced inflammatory responses. However, the specific intestinal microbes and microbial metabolites linked to intestinal homeostasis in suckling lambs remain unclear.

Results: In this study, diarrheic lambs showed significantly higher serum diamine oxidase (DAO) activity, D-lactate (D-LA), and pro-inflammatory cytokine levels than healthy lambs. We then compared gut microbial composition and metabolite profiles between healthy and diarrheic suckling lambs. Diarrheal lambs exhibited gut microbiota dysbiosis, characterized by an elevated Bacillota (syn. Firmicutes)/Bacteroidota (syn. Bacteroidetes) ratio, reduced abundance of beneficial commensals including Phocaeicola vulgatus and Bacteroides fragilis, and proliferation of the opportunistic pathogen Clostridium perfringens. Metabolomic analysis showed that, in diarrheic lambs, the tryptophan metabolism pathway was reduced with lower levels of indole-3-carboxaldehyde (IAld) and 5-hydroxyindole-3-acetic acid (5-HIAA) than in healthy lambs. Fecal microbiota transplantation experiments showed that transplantation of microbiota from diarrheic lambs partially recapitulated the donor-associated microbial, metabolic, and inflammatory phenotypes in recipient mice. Finally, functional validation using a dextran sulfate sodium (DSS)-induced colitis model revealed that supplementation with IAld and 5-HIAA significantly alleviated DSS-induced intestinal inflammation and barrier damage, accompanied by downregulated expression of genes related to the Tlr4-Myd88-Nfκb signaling pathway.

Conclusions: Our findings indicate that the gut microbiota-derived tryptophan metabolites IAld and 5-HIAA alleviated inflammation and improved intestinal epithelial barrier function by enhancing tight junction integrity, while also reducing the expression of Tlr4/Myd88/Nfκb pathway-related inflammatory signaling molecules.

Background: Heat stress compromises dairy cow productivity and metabolic health through impaired nutrient partitioning and oxidative stress. Cobalamin is an essential cofactor for methylmalonyl-CoA mutase, the key enzyme regulating ruminal propionate production and hepatic gluconeogenic metabolism. However, the underlying molecular mechanisms, particularly the hepatic transcriptional responses to cobalamin under heat stress conditions, remain unclear. This study evaluated the effects of coated cobalamin (CCA) supplementation on lactation performance, nutrient digestibility, rumen fermentation, blood metabolites, and hepatic transcriptome in heat-stressed Holstein cows.

Results: Forty Holstein cows (2.25 ± 0.07 parity; 105 ± 10.4 DIM; 41.5 ± 6.83 kg/d milk yield) were assigned to two groups (n = 20) in a randomized block design: (1) control (CON; without CCA) or (2) CCA (addition of CCA at 6 g/d). The experimental period was 64 days, during which the mean temperature-humidity index was 77.1 ± 2.49 (mean ± SD). Respiratory rate was lower in CCA-fed cows than in CON cows. Nutrient intake did not differ, whereas fat-corrected milk, milk protein yields, and feed efficiency were greater for cows receiving CCA. Supplementation with CCA increased ruminal total volatile fatty acid concentration and propionate proportion, but decreased acetate-to-propionate ratio. Apparent digestibilities of organic matter and neutral detergent fiber were greater in the CCA group compared with the CON. Plasma glutathione peroxidase, total antioxidant capacity, and cobalamin were greater, but tumor necrosis factor-α and interleukin-1β were lower for cows in the CCA group. Liver transcriptome analysis revealed that mitogen-activated protein kinase (MAPK), phagosome, and peroxisome proliferator-activated receptor (PPAR) signaling pathways, along with the JUN, FOS, and GADD45G gene family, were key pathways and genes through which CCA regulated hepatic metabolism in heat-stressed cows.

Conclusion: Coated cobalamin addition alleviates heat stress, and increases lactation performance, rumen propionate production, and antioxidant status in dairy cows. Hepatic MAPK signaling pathway mediated the metabolic benefits of CCA in heat-stressed dairy cows. These findings support CCA supplementation as a practical nutritional strategy for mitigating heat stress and provide a mechanistic basis for understanding how targeted nutrient delivery modulates systemic metabolism through hepatic transcriptional regulation.

Background: Green tea residue (GTR) is an abundant by-product rich in polyphenols. This study aimed to investigate the effects of GTR on growth performance, rumen microbiota, and systemic metabolism in finishing beef cattle.

Results: Forty-five 18‑month‑old finishing Angus steers with an average initial body weight of 474.44 ± 14.03 kg (mean ± SD) were individually housed and randomly assigned to three dietary treatments (n = 15 per group) using stratified randomization by initial body weight: control group (CG group, 150 g rice straw), low-dose GTR group (LG group, 75 g rice straw +75 g GTR), and high-dose GTR group (HG group, 150 g GTR). The feeding trial lasted 70 d with a 10-day adaptation period. To elucidate the regulatory mechanisms of GTR on beef cattle growth, we thoroughly assessed growth performance, nutrient digestibility, ruminal fermentation parameters, conducted bacterial 16S rRNA sequencing, analysed plasma biochemical and antioxidant markers, and executed an untargeted plasma metabolomic analysis. The LG group tended to increase average daily gain (ADG). Meanwhile, the LG group exhibited elevated plasma concentrations of β-hydroxybutyrate and glucose, increased activities of superoxide dismutase and glutathione S-transferase, an increased glutathione (GSH)/glutathione disulfide (GSSG) ratio, and reduced GSSG content. GTR treatment decreased reactive oxygen species and oxidative stress index. Furthermore, dietary GTR significantly modified the rumen microbial community structure, enriching Xylanibacter and Prevotellaceae_UCG-003, while reducing the abundance of Rikenellaceae_RC9_gut_group. Plasma metabolomics revealed that GTR treatment enriched GSH Metabolism and the Pentose Phosphate Pathway. Notably, gamma-glutamylcysteine was identified as a key mediator of the association between Xylanibacter and ADG in fattening beef cattle supplemented with GTR.

Conclusions: Dietary supplementation with 75 g/steer/d GTR improved growth performance and systemic antioxidant capacity in finishing beef cattle by modulating the rumen microbiota and activating the glutathione system. GTR represents a promising functional feed additive that simultaneously valorizes tea by‑products and enhances livestock productivity.

Background: As a diverse and abundant component of the rumen ecosystem, viruses interact with other microorganisms and are thought to influence microbial metabolism and host productivity. However, how the rumen virome responds to seasonal fluctuations in extreme environments remains poorly understood. Here, metagenomic analyses were used to investigate temporal dynamics of viral diversity, functional potential, and virus-host associations in the rumen virome of yak and cattle on the Qinghai-Tibet Plateau across warm and cold seasons.

Results: Rumen viral communities exhibited pronounced seasonal variation in both yaks and cattle, with higher alpha diversity observed during the cold season than in the warm season. Across seasons, the yak rumen virome showed greater alpha diversity and community stability than that of cattle. In total, 27,353 temperate and 31,976 virulent viral operational taxonomic units (vOTUs) were identified, predominantly belonging to the class Caudoviricetes. These viruses were linked to microbial hosts spanning 24 bacterial and 8 archaeal phyla, with Bacteroidota and Bacillota representing the dominant lineages. Virus-host associations were more numerous in the cold season and showed distinct host-specific patterns between yaks and cattle. Cold-season virome exhibited reduced diversity of anti-defense genes and enrichment of auxiliary metabolic genes (AMGs) associated with fatty acid metabolism and hemicellulose degradation. Notably, greater divergence between yaks and cattle was observed during the cold season: the yak rumen virome was enriched in pathways related to amino acid, lipid, and energy metabolism, as well as cellulose-degrading CAZyme families, whereas the cattle rumen virome showed enrichment in general carbohydrate metabolism and replication and repair processes.

Conclusion: Seasonal plasticity of rumen DNA virome and pronounced interspecific divergence between yaks and cattle provide insight into their distinct microbial processes in the harsh environment of the Qinghai-Tibet Plateau. These findings suggest that the rumen DNA virome exhibits complex ecological and functional responses to seasonal variation and may be associated with host-microbiome interactions and nutrient utilization under environmental stress. This study highlights the ecological relevance of rumen viral genomes in understanding virus-microbiome interactions, microbial adaptation, and nutrient utilization in high-altitude ruminants.

This review summarizes the regulatory roles of polyphenolic compounds in animal skeletal health through the gut-bone axis and explores their benefits for animal nutrition. First, this review focuses on their key roles in maintaining skeletal homeostasis through gut microbiota, intestinal barrier integrity, immune regulation, microbial metabolites, and endocrine signaling. Then, from a biological mechanism perspective, we summarize how polyphenolic compounds regulate animal bone metabolism by reshaping gut microbiota composition, promoting short-chain fatty acid production, enhancing intestinal barrier function, reducing oxidative stress and systemic inflammation, and modulating osteogenic and osteoclastic signaling pathways. Furthermore, this review comprehensively discusses representative subclasses of polyphenolic compounds (including flavonoids, phenolic acids, lignans, stilbenes, and other bioactive compounds) and elucidates their mechanisms in animal skeletal protection and nutritional regulation. In conclusion, this review provides a theoretical foundation for understanding the polyphenol-mediated gut-bone axis regulatory mechanisms and offers new insights into nutritional strategies for promoting bone health in animals.