Salmonella Typhimurium infection disrupts but continuous feeding of Bacillus based probiotic restores gut microbiota in infected hens

Vaccine protection of broilers against various doses of wild-type Salmonella Typhimurium and changes in gut microbiota

This study evaluated the impact of vaccine diluents (peptone or water) on the protective effects of Salmonella Typhimurium (S. Typhimurium) vaccine. Vaccinated broilers were challenged with different doses of wild-type S. Typhimurium through dust. At the time of cull, vaccine load was highest in caeca and lowest in spleen. Wild-type S. Typhimurium was detectable after 24 hrs only in the vaccinated birds challenged with 108 CFU and positive control. S. Typhimurium load was lower in the organs of the groups challenged with 104 and 106 compared to the 108 CFU group. The caecal microbiota alpha diversity of the vaccinated or vaccinated and challenged chickens differed from the positive and negative control groups. Beta diversity of the positive control clustered separately from all other treatment groups, showing that vaccine caused minimal changes in gut microbiota structure. The vaccinated and/or wild-type challenged chickens showed significantly higher abundance of Anaerostignum, Lachnoclostridium, Intestinimonas, Colidextribacter, Monoglobus, Acetanaerobacterium and Subdoligranulum. Outcomes from this study demonstrate that the vaccine effectively protected broiler chickens from S. Typhimurium infection and helped maintain a more stable gut microbiota structure, reducing the impact of S. Typhimurium on gut health. Vaccine diluent did not affect gut microbiota composition.

The host susceptibility/resistance-related genes and gut microbial characteristics in Salmonella pullorum-infected chickens

Pullorum disease is a bacterial disease caused by Salmonella pullorum in chickens, which is characterized by gastrointestinal infection and diarrhea. In traditional perspectives, research on pullorum disease primarily focused on clinical symptoms, epidemiological characteristics, and the pathogenic sites. This study, however, approaches the subject from the standpoint of host genetic basis and gut microbiota. For the positive and negative offspring chicks, which are the offspring of positive roosters and hens and negative roosters and hens, respectively, we conducted whole-genome association analysis and identified 195 SNPs and 79 significant InDels on the host genome that were associated with susceptibility/resistance to pullorum disease. A total of 77 genes were annotated, among which MYH7, ATP2A3, and CACNA1S exhibited variations in the exons. After infection with S. pullorum, the diversity and community structure of the gut microbiota in the chicken also underwent significant changes. Lactobacillus, Escherichia_Shigella, and Klebsiella were dominant bacteria in the dead negative offspring chicks with significantly higher abundance compared to the survival negative offspring chicks. These significant changes in host genome and bacterial abundance suggest that they may be associated with the susceptibility/resistance of pullorum disease.IMPORTANCEPullorum disease can be transmitted vertically and horizontally. Population purification and antibiotic treatment are the main methods for preventing and treating this disease, but they are associated with issues, such as high cost, poor accuracy, bacterial resistance, and overused antibiotics. In traditional perspectives, research on pullorum disease primarily focused on clinical symptoms, epidemiological characteristics, and the pathogenic sites. This study, however, approaches the subject from the standpoint of host genetic basis and gut microbiota. Using the genome-wide association analysis and microbiome comparison analysis, with chicken death and survival following Salmonella pullorum infection as phenotypes, we identified significant genetic variations (e.g., MYH7, ATP2A3, and CACNA1S) and gut microbiota (e.g., Lactobacillus, Escherichia_Shigella, Bacillus, and Enterococcus_cecorum) that may relate to susceptibility/resistance of pullorum disease. These results indicate that the infection of chickens with S. pullorum and the achievement of vertical transmission may be related to the host genome and gut microbiota.

Comparative effects of selenium-enriched lactobacilli and selenium-enriched yeast on performance, egg selenium enrichment, antioxidant capacity, and ileal microbiota in laying hens

BACKGROUND

Organic selenium (Se) has gained recognition in poultry nutrition as a feed additive to boost production and Se deposition in eggs and tissues, owing to its high bioavailability, efficient tissue accumulation and minimal toxicity. Selenium-enriched yeast (SeY) is a well-established source, while selenium-enriched lactobacilli (SeL), a newer alternative, offers the added benefits of probiotics. This study examined the effects of SeY and SeL on egg quality, antioxidant capacity, Se deposition, and gut health in laying hens. After a two-week pre-treatment with a Se-deficient diet (SeD), 450 Hy-Line Brown laying hens (30-week-old) were assigned into five dietary groups with six replicates of 15 hens each. The groups included a SeD, SeD supplemented with 1.5 mg Se/kg from SeY (SeY15), or 1.5, 3.0, and 6.0 mg Se/kg from SeL (SeL15, SeL30, SeL60). The feeding trial lasted for 12 weeks.

RESULTS

SeY15 and SeL15 improved the feed-to-egg ratio (P < 0.05) in the latter stages. Haugh units were significantly increased (P < 0.05) in the SeY15 and SeL30 groups, while darker yolk color (P < 0.05) was observed in the SeY15, SeL15, and SeL60 groups. All Se-supplemented diets increased Se content in whole eggs, albumen, and yolk (P < 0.05), while SeL groups showed a dose-dependent effect. Antioxidant enzyme activities increased, and MDA content decreased in the serum (P < 0.05), with SeY15 showing the highest GSH-Px levels (P < 0.05). SeL60 increased serum alkaline phosphatase and aspartate transaminase, and distorted the liver architecture (P < 0.05). Se-diets reduced concentrations of reactive oxygen species (ROS) in the ileum and liver (P < 0.05). SeL15 improved the ileal villus height-to-crypt depth ratio (P < 0.05). SeY15 and/or SeL15 up-regulated TXNRD1 and SEPHS1 mRNA while down-regulating SCLY expression in the liver. SeY15 altered ileal microbiota by increasing both beneficial and pathogenic bacteria, whereas SeL15 predominantly boosted beneficial bacteria.

CONCLUSION

SeL integrates the antioxidant properties of organic Se with the probiotic benefits on gut health, resulting in a performance-enhancing effect comparable to that of SeY. However, high SeL level (6.0 mg Se/kg) compromised productivity and metabolic functions while enhancing Se deposition.

Correlation analysis of the impact of Clonorchis sinensis juvenile on gut microbiota and transcriptome in mice

Clonorchiasis remains a non-negligible global zoonosis, imposing serious socio-economic burdens in endemic regions. The interplay between gut microbiota and the host transcriptome is crucial for maintaining health; however, the impact of Clonorchiasis sinensis juvenile infection on these factors is still poorly understood. This study aimed to investigate their relationship and potential pathogenic mechanisms. The BALB/c mouse model of early infection with C. sinensis juvenile was constructed. Pathological analyses revealed that C. sinensis juvenile triggered liver inflammation, promoted intestinal villi growth, and augmented goblet cell numbers in the ileum. Additionally, the infection altered the diversity and structure of gut microbiota, particularly affecting beneficial bacteria that produce short-chain fatty acids, such as Lactobacillus and Muribaculaceae, and disrupted the Firmicutes/Bacteroidetes ratio. Gut transcriptome analysis demonstrated an increase in the number of differentially expressed genes (DEGs) as infection progressed. Enriched Gene Ontology items highlighted immune and detoxification-related processes, including immunoglobulin production and xenobiotic metabolic processes. Kyoto Encyclopedia of Genes and Genomes pathway analysis further indicated involvement in circadian rhythm, as well as various detoxification and metabolic-related pathways (e.g., glutathione metabolism and glycolysis/gluconeogenesis). Prominent DEGs associated with these pathways included Igkv12-41, Mcpt2, Arntl, Npas2, Cry1, and Gsta1. Correlation analysis additionally identified Bacteroides_sartorii as a potential key regulator in the interaction between gut microbiota and transcriptome. This study sheds light on the alterations in gut microbiota and transcriptome in mice following C. sinensis juvenile infection, as well as their correlation, laying a foundation for a better understanding of their interaction during infection.

IMPORTANCE

This study highlighted the impact of C. sinensis juvenile infection on the gut microbiota and transcriptome of BALB/c mice. It induced liver inflammation, promoted intestinal villi growth, and altered goblet cell numbers. The infection also disrupted the diversity and structure of gut microbiota, particularly affecting beneficial bacteria. Transcriptome analysis revealed increased expression of genes related to immune response and detoxification processes. Important pathways affected included circadian rhythm, glutathione metabolism, and glycolysis/gluconeogenesis. Notable genes implicated included Igkv12-41, Mcpt2, Arntl, Npas2, Cry1, and Gsta1. Bacteroides_sartorii emerged as a potential key regulator in this interaction.

Probiotics in Poultry: Unlocking Productivity Through Microbiome Modulation and Gut Health

This review explores the role of probiotics in improving productivity and gut health in poultry through microbiome modulation, particularly during early life. Gut health is pivotal to poultry performance, influencing nutrient absorption, immune function, and disease resistance. Early-life interventions target the microbiome to shape long-term health and productivity. Probiotics, live microorganisms providing health benefits, improve gut health through the competitive exclusion of pathogens, immune modulation, antimicrobial compound production, and enhancing gut barrier integrity. Applying probiotics improves growth performance, feed conversion efficiency, body weight gain, and carcass quality by promoting lean muscle growth and reducing fat deposition. For laying hens, probiotics enhance egg production and quality. These benefits are linked to better nutrient utilization, a well-balanced microbiome, and reduced gastrointestinal disorders. However, the efficacy of probiotics depends on strain specificity, dosage, and administration methods. Factors like environmental conditions, storage stability, and interactions with other feed additives also influence their effectiveness. Despite these challenges, advancements in microbiome research and probiotic technologies, such as precision probiotics and synbiotics, provide promising solutions. Future research should focus on optimizing formulations, understanding host-microbiome interactions, and leveraging new technologies for targeted microbiome management.

Progress on the prevention of poultry Salmonella with natural medicines

Salmonella infection is an acute and systemic disease of poultry, primarily affecting young birds. The mortality rate of chicken within one week of age can reach up to 40 %. Surviving individuals may become carriers of the bacteria, leading to latent infections that can result in bacterial residues in meat and egg products, posing serious threats to human food safety and health. Antibiotic therapy is one of the most conventional treatments for Salmonella infections in birds. However, the current abuse of antibiotics has accelerated the mutation of pathogenic bacteria to generate antibiotic-resistant strains. Thus, the effectiveness of treatment with antibiotics alone is gradually diminishing. To address this threat, researchers have explored the use of natural products to enhance the immune system of poultry for preventing Salmonella infections. This study aims to provide a comprehensive review, systematically summarizing recent research progress of the application of natural medicines on poultry Salmonella infection.

Dietary supplementation of compound probiotics to improve performance, egg quality, biochemical parameters and intestinal morphology of laying hens

The purpose of this study was to investigate the effects of dietary supplementation of compound probiotics on the performance, egg quality, biochemical parameters and intestinal morphology of laying hens. A total of 180 healthy 200-day-old Hyline Brown laying hens with similar initial laying rate (87.5% ± 0.2%) were randomly divided into the control group and the treatment group. Each group included 6 replicates and each replicate included 15 laying hens. The control group was provided a basal diet, while the treatment group received the basal diet supplemented with compound probiotics. The experiment lasted for 52 days. The study indicated the following outcomes: (1) The laying rate (LR) and average egg weight (AEW) of laying hens in the treatment group were significantly higher than those of the control group (p < 0.05), whereas the feed-to-egg ratio (F/E) was significantly lower (p < 0.05); (2) The yolk weight (YW), egg shape index (ESI) and albumen height (AH) were significantly higher (p < 0.05), whereas the eggshell percentage (EP) was significantly lower (p < 0.05) after the dietary supplementation of compound probiotics; (3) The treatment group significantly decreased in total cholesterol (TC), triglyceride (TG), alanine aminotransferase (ALT), aspartate aminotransferase (AST), malondialdehyde (MDA), immunoglobulin A (IgA), and immunoglobulin G (IgG) levels in serum compared to the CON group (p < 0.05). Additionally, serum levels of total protein (TP), globulin (GLB), albumin (ALB), high-density lipoprotein (HDL), alkaline phosphatase (ALP), and total antioxidant capacity (T-AOC) were significantly higher in the treatment group (p < 0.05); (4) The supplementation of compound probiotics to laying hen diets led to a significant reduction in crypt depth (CD) and the ratio of villus height to crypt depth (V/C) in the jejunum compared to the CON group (p < 0.05). In conclusion, the supplementation of compound probiotics can regulate the body metabolism and improve the intestinal morphology, thus enhancing the antioxidant capacity and immune function of the body, which in turn improves the performance and egg quality of laying hens.

Pre-Harvest Non-Typhoidal Salmonella Control Strategies in Commercial Layer Chickens

Non-typhoidal Salmonella (NTS) infections in poultry, particularly in commercial-layer chickens, pose a critical risk to food safety and public health worldwide. NTS bacteria can remain undetected in poultry flocks, contaminating products and potentially leading to gastroenteritis in humans. This review examines pre-harvest control strategies for NTS in layer chickens, including biosecurity protocols, vaccinations, feed additives, genetic selection, and environmental management. These strategies have substantially reduced Salmonella colonization and product contamination rates in the commercial layer industry. By evaluating these strategies, this review highlights the importance of integrated control measures to limit NTS colonization, reduce antimicrobial resistance, and improve poultry health. This review aims to provide producers, researchers, and policymakers with insights into effective practices to minimize Salmonella contamination and enhance both animal and human health outcomes.

The Interactive Effects of Nutrient Density and Breed on Growth Performance and Gut Microbiota in Broilers

This study investigated whether variations in growth response to low nutrient density across breeds are linked to microbiota regulation. Arbor Acres (AA) and Beijing-You (BY) were fed high- (HN) and low-nutrient (LN) diets from day (d) 0 to d42. Body weight, feed intake, and intestinal measurements were recorded, and microbiota from the ileum and cecum were analyzed on d7, d21, and d42. Results showed that AA broilers had greater growth performance with a lower feed conversion ratio (FCR) and greater average daily gain (ADG) than BY chickens. The LN diet negatively affected AA broiler growth due to impaired intestinal development, while BY chickens compensated by increasing feed intake. Microbiota composition was primarily affected by breed than by nutrient density, with AA broilers having more beneficial bacteria and BY chickens having more short-chain fatty acid (SCFA)-producing bacteria. The LN diets reduced anti-inflammatory bacteria such as Shuttleworthia and Eisenbergiella in the cecum on d7. By d21, LN diets decreased Lactobacillus and increased proinflammatory Marvinbryantia, potentially impairing growth. However, LN diets enriched SCFA-producing bacteria like Ruminococcaceae_UCG.013, Eisenbergiella, and Tyzzerella in BY chickens and Faecalitalea in AA broilers by d21, which may benefit gut health. By d42, LN diets reduced genera linked to intestinal permeability and fat deposition, including Ruminococcus_torques_group, Romboutsia, Erysipelatoclostridium, and Oscillibacter. Additionally, LN diets enriched Christensenellaceae_R-7_group in AA broilers, associated with intestinal barrier integrity, and increased anti-inflammatory bacteria Alistipes and Barnesiella in AA broilers and BY chickens, respectively, by d42. Overall, AA broilers were more susceptible to reduced nutrient density due to impaired intestinal development, while BY chickens adapted better by increasing feed intake. The microbiota responses to low nutrient density varied over time, potentially negatively affecting gut health in the early stage and growth in the middle stage but possibly improving lipid deposition and gut health in the middle and late stages.

Compound Bacillus improves eggshell quality and egg metabolites of hens by promoting the metabolism balance of calcium and phosphorus and uterine cell proliferation

Probiotics have beneficial effects on improving egg quality, but there is little research about the effect of probiotics on metabolite composition, and the mechanisms are not yet fully understood. The aim of this study was to investigate the potential mechanisms by which compound Bacillus improves egg quality and metabolite composition. A total of 20,000 Jingfen No. 6 laying hens at 381 d old were randomly divided into two treatments: control group with a basal diet, and the basal diet with 5 × 108 CFU/kg compound Bacillus supplementation (Ba) group. The trial lasted eight weeks. The results showed that compound Bacillus improved the gloss and strength of eggshells and reduced the ratio of sand-shell eggs by 23.8%. Specifically, the effective layer of eggshell was thicker and its calcite column was closely connected. Compound Bacillus increased the contents of beneficial fatty acids in the egg yolk, and lipids and lipid-like molecules in the albumen (P < 0.01), while decreased the contents of total cholesterol, triglycerides, and benzene ring compounds in the egg yolk and organic oxygen compounds in the albumen (P < 0.01). In addition, the compound Bacillus increased the calcium absorption in the duodenum by up-regulating the expression of transporters and serum hormone synergism (P < 0.05), and promoted metabolic balance of calcium and phosphorus. Simultaneously, uterine transcriptome showed that the expression of ChaC glutathione specific gamma-glutamylcyclotransferase 1 (CHAC1), glycoprotein-N-acetylgalactosamine 3-beta-galactosyltransferase 1 (C1GALT1), phosphatidylinositol-4-phosphate 5-kinase type 1 beta (PIP5K1B), methylenetetrahydrofolate dehydrogenase 2 (MTHFD2), brain enriched myelin associated protein 1 (BCAS1), and squalene epoxidase (SQLE) genes were increased (P < 0.01), indicating that nutrient metabolism activity was enhanced. The expression of the BCAS1, C1GALT1, KLF transcription factor 13 (KLF13), and leucine rich repeat neuronal 1 (LRRN1) was increased (P < 0.01), indicating that the cell proliferation was enhanced, which slowed uterus aging. In conclusion, compound Bacillus improved the eggshell strength and metabolite composition in the egg by promoting metabolic balance of calcium and phosphorus, cell proliferation, and nutrient metabolism in the uterus.

Protective effects of potential probiotics Lacticaseibacillus rhamnosus SN21-1 and Lactiplantibacillus plantarum SN21-2 against Salmonella typhimurium infection in broilers

This study aimed to explore the probiotic characteristics of Lacticaseibacillus rhamnosus SN21-1 and Lactiplantibacillus plantarum SN21-2 by genotype and phenotype analysis, assess their safety in vitro and in vivo, and investigate the effects of L. rhamnosus SN21-1 and L. plantarum SN21-2 on Salmonella typhimurium-infected broilers in an in vivo experiment. L. rhamnosus SN21-1 and L. plantarum SN21-2 showed antimicrobial activity against pathogens, including S. Typhimurium, resistance to simulated gastrointestinal digestive fluid, and adhesion to HT-29 cells. In addition, L. rhamnosus SN21-1 and L. plantarum SN21-2 showed no resistance to most common antimicrobial agents and no haemolysis in vitro. Whole-genome sequence analyses of L. rhamnosus SN21-1 and L. plantarum SN21-2 provided basic genomic information, functional genes underlying the probiotic characteristics, and evidence of safety. Furthermore, feeding with L. rhamnosus SN21-1 or L. plantarum SN21-2 for 28 d had no significant effect on the growth or blood biochemical parameters of the broilers, and hematoxylin-eosin staining revealed no liver, spleen, heart, or kidney damage. Additionally, L. rhamnosus SN21-1 or L. plantarum SN21-2 did not translocate to the blood, liver, spleen, heart, or kidney of the broilers. Moreover, L. rhamnosus SN21-1 and L. plantarum SN21-2 significantly reduced S. Typhimurium counts in the faeces and caecal contents of S. Typhimurium-infected broilers and reduced small intestinal bleeding in S. Typhimurium-infected broilers. Consequently, L. rhamnosus SN21-1 and L. plantarum SN21-2 have excellent probiotic characteristics and are safe for use as anti-S. typhimurium probiotics in broilers.

Research advancements on the diversity and host interaction of gut microbiota in chickens

The maintenance of host health and immune function is heavily dependent on the gut microbiota. However, the precise contribution of individual microbial taxa to regulating the overall functionality of the gut microbiome remains inadequately investigated. Chickens are commonly used as models for studying poultry gut microbiota, with high-throughput 16S rRNA sequencing has emerged as a valuable tool for assessing both its composition and functionality. The interactions between the gut's microbial community and its host significantly influence health outcomes, disease susceptibility, and various mechanisms affecting gastrointestinal function. Despite substantial research efforts, the dynamic nature of this microbial ecosystem has led to inconsistencies in findings related to chicken gut microbiota, which is largely attributed to variations in rearing conditions. Consequently, the interaction between the chickens' gut microflora and its host remains inadequately explored. This review highlights recent advances in understanding these relationships, with a specific focus on microbial composition, diversity, functional mechanisms, and their potential implications for improving poultry production.

Dietary bile acids supplementation protects against Salmonella Typhimurium infection via improving intestinal mucosal barrier and gut microbiota composition in broilers

BACKGROUND

Salmonella Typhimurium (S. Typhimurium) is a common pathogenic microorganism and poses a threat to the efficiency of poultry farms. As signaling molecules regulating the interaction between the host and gut microbiota, bile acids (BAs) play a protective role in maintaining gut homeostasis. However, the antibacterial effect of BAs on Salmonella infection in broilers has remained unexplored. Therefore, the aim of this study was to investigate the potential role of feeding BAs in protecting against S. Typhimurium infection in broilers.

METHODS

A total of 144 1-day-old Arbor Acres male broilers were randomly assigned to 4 groups, including non-challenged birds fed a basal diet (CON), S. Typhimurium-challenged birds (ST), S. Typhimurium-challenged birds treated with 0.15 g/kg antibiotic after infection (ST-ANT), and S. Typhimurium-challenged birds fed a basal diet supplemented with 350 mg/kg of BAs (ST-BA).

RESULTS

BAs supplementation ameliorated weight loss induced by S. Typhimurium infection and reduced the colonization of Salmonella in the liver and small intestine in broilers (P < 0.05). Compared to the ST group, broilers in ST-BA group had a higher ileal mucosal thickness and villus height, and BAs also ameliorated the increase of diamine oxidase (DAO) level in serum (P < 0.05). It was observed that the mucus layer thickness and the number of villous and cryptic goblet cells (GCs) were increased in the ST-BA group, consistent with the upregulation of MUC2 gene expression in the ileal mucosa (P < 0.05). Moreover, the mRNA expressions of Toll-like receptor 5 (TLR5), Toll-like receptor 4 (TLR4), and interleukin 1 beta (IL1b) were downregulated in the ileum by BAs treatment (P < 0.05). 16S rDNA sequencing analysis revealed that, compared to ST group, BAs ameliorated the decreases in Bacteroidota, Bacteroidaceae and Bacteroides abundances, which were negatively correlated with serum DAO activity, and the increases in Campylobacterota, Campylobacteraceae and Campylobacter abundances, which were negatively correlated with body weight but positively correlated with serum D-lactic acid (D-LA) levels (P < 0.05).

CONCLUSIONS

Dietary BAs supplementation strengthens the intestinal mucosal barrier and reverses dysbiosis of gut microbiota, which eventually relieves the damage to the intestinal barrier and weight loss induced by S. Typhimurium infection in broilers.

Live black soldier fly larvae as environmental enrichment for native chickens: implications for bird performance, welfare, and excreta microbiota

Dietary live insect larvae were recently proposed for use in laying hens and broiler-intensive chicken farming as an innovative form of environmental enrichment, but their use in native dual-purpose chickens has never been investigated. This study aims to evaluate the effects of live black soldier fly (BSF) larvae as environmental enrichment in two autochthonous dual-purpose chicken breeds, namely Bionda Piemontese (BP) and Bianca di Saluzzo (BS), in terms of bird performance, behaviour, integument status, excreta corticosterone metabolites (ECMs), and microbiota analyses. A total of 90 BP and 90 BS hens aged 308 days old were randomly distributed between two treatment groups (three replicates/group/breed, 15 hens/replicate). For the following 90 days, the control group (C) was fed a commercial feed only, whereas the BSF group was fed the commercial diet plus BSF live larvae calculated at 6% of the expected daily feed intake (DFI). Larva ingestion time, bird performance, integument scores, and behavioural observations were assessed at regular intervals, and excreta samples were collected to evaluate ECM and microbiota. The larva ingestion time became faster over the course of the experimental trial (P < 0.001). The DFI of BSF-fed hens was lower than that of C hens independently of breed (P < 0.001), whereas only in the BS hens, the live weight of the BSF-fed group was greater than that of the C group (P < 0.01). The BSF-fed BP hens showed a higher laying rate and feed conversion ratio compared with BSF-BS (P < 0.05). Better total integument scores were observed in BSF-fed BP hens compared with C-birds (P < 0.05). The BSF-fed hens displayed higher frequencies of preening, trotting, and wing flapping than C, as well as a lower incidence of severe feather pecking (P < 0.05). An increase in allopreening was only identified in BSF-fed BS hens with respect to the C hens (P < 0.001). No differences in ECM and faecal microbiota were observed between treatment groups. In conclusion, the administration of BSF live larvae as environmental enrichment has the potential to positively influence the welfare of both BP and BS chickens, by enhancing the frequency of positive behaviours whilst reducing severe feather pecking, without affecting their excreta microbiota. BSF larva administration also has the potential to improve the productive performance and the plumage status of the BP breed.

Co-exposure to polyethylene fiber and Salmonella enterica serovar Typhimurium alters microbiome and metabolome of in vitro chicken cecal mesocosms

Humans and animals encounter a summation of exposures during their lifetime (the exposome). In recent years, the scope of the exposome has begun to include microplastics. Microplastics (MPs) have increasingly been found in locations, including in animal gastrointestinal tracts, where there could be an interaction with Salmonella enterica serovar Typhimurium, one of the commonly isolated serovars from processed chicken. However, there is limited knowledge on how gut microbiomes are affected by microplastics and if an effect would be exacerbated by the presence of a pathogen. In this study, we aimed to determine if acute exposure to microplastics in vitro altered the gut microbiome membership and activity. The microbiota response to a 24 h co-exposure to Salmonella enterica serovar Typhimurium and/or low-density polyethylene (PE) microplastics in an in vitro broiler cecal model was determined using 16S rRNA amplicon sequencing (Illumina) and untargeted metabolomics. Community sequencing results indicated that PE fiber with and without S. Typhimurium yielded a lower Firmicutes/Bacteroides ratio compared with other treatment groups, which is associated with poor gut health, and overall had greater changes to the cecal microbial community composition. However, changes in the total metabolome were primarily driven by the presence of S. Typhimurium. Additionally, the co-exposure to PE fiber and S. Typhimurium caused greater cecal microbial community and metabolome changes than either exposure alone. Our results indicate that polymer shape is an important factor in effects resulting from exposure. It also demonstrates that microplastic-pathogen interactions cause metabolic alterations to the chicken cecal microbiome in an in vitro chicken cecal mesocosm.

IMPORTANCE

Researching the exposome, a summation of exposure to one's lifespan, will aid in determining the environmental factors that contribute to disease states. There is an emerging concern that microplastic-pathogen interactions in the gastrointestinal tract of broiler chickens may lead to an increase in Salmonella infection across flocks and eventually increased incidence of human salmonellosis cases. In this research article, we elucidated the effects of acute co-exposure to polyethylene microplastics and Salmonella enterica serovar Typhimurium on the ceca microbial community in vitro. Salmonella presence caused strong shifts in the cecal metabolome but not the microbiome. The inverse was true for polyethylene fiber. Polyethylene powder had almost no effect. The co-exposure had worse effects than either alone. This demonstrates that exposure effects to the gut microbial community are contaminant-specific. When combined, the interactions between exposures exacerbate changes to the gut environment, necessitating future experiments studying low-dose chronic exposure effects with in vivo model systems.

Prebiotic galactooligosaccharide feed modifies the chicken gut microbiota to efficiently clear Salmonella

Chicken meat is contaminated with Salmonella from the gut of infected chickens during slaughter. Eradication of Salmonella from broiler chickens through hygiene measures and/or vaccination is not cost-effective; complementary approaches are required. A mature gut microbiota obstructs Salmonella infection in chickens, and deliberate fortification of colonization resistance through prebiotic feed formulations would benefit public health and poultry production. Prebiotic galactooligosaccharides hastens Salmonella clearance from the gut of infected chickens. To better understand the role of galactooligosaccharides in colonization resistance, broiler chickens were raised on a wheat-soybean meal-based feed, with or without galactooligosaccharides for the first 24 days of life. Chickens were orally challenged with Salmonella enterica serovar Enteritidis at 20 days and the effect of supplementary galactooligosaccharides characterized by profiling Salmonella colonization, gut microbiota, innate immune response, and cecal short-chain fatty acid concentrations. Exposure to dietary galactooligosaccharides shortened the time to clear S. Enteritidis from the ceca. Differential abundance analysis of the cecal microbiota associated Salmonella challenge with a bacterial taxon belonging to the Acidaminococcaceae family (P < 0.005). Increased cecal concentrations of the short-chain fatty acids propionate and valerate were measured in Salmonella-challenged chickens sustained on either control or galactooligosaccharide-supplemented feed relative to mock-challenged controls; but far greater concentrations were detected in chickens fed a galactooligosaccharide-supplemented diet in early life. The abundance of the Acidaminococcaceae taxon exhibited a positive correlation with the cecal concentrations of propionate (ρ = 0.724, P = 0.008) and valerate (ρ = 0.71, P = 0.013). The absence of cecal pro-inflammatory transcriptional responses suggest that the rapid Salmonella clearance observed for the galactooligosaccharide-supplemented diet was not linked to innate immune function.

IMPORTANCE

Work presented here identifies bacterial taxa responsible for colonization resistance to Salmonella in broiler chickens. Deliberate cultivation of these taxa with prebiotic galactooligosaccharide has potential as a straight-forward, safe, and cost-effective intervention against Salmonella. We hypothesize that catabolism of galactooligosaccharide and its breakdown products by indigenous microorganisms colonizing the chicken gut produce excess levels of propionate. In the absence of gross inflammation, propionate is inimical to Salmonella and hastens intestinal clearance.

Impacts of Dietary Standardized Ileal Digestible Lysine to Net Energy Ratio on Lipid Metabolism in Finishing Pigs Fed High-Wheat Diets

The present study aimed to investigate the impacts of dietary standardized ileal digestible lysine to net energy (SID Lys:NE) ratio on lipid metabolism in pigs fed high-wheat diets. Thirty-six crossbred growing barrows (65.20 ± 0.38 kg) were blocked into two treatment groups, fed high-wheat diets with either a high SID Lys:NE ratio (HR) or a low SID Lys:NE ratio (LR). Each treatment group consisted of three replicates, with six pigs per pen in each replicate. The diminishing dietary SID Lys:NE ratio exhibited no adverse impacts on the carcass trait (p > 0.05) but increased the marbling score of the longissimus dorsi muscle (p < 0.05). Meanwhile, LR diets tended to increase the serum triglyceride concentration (p < 0.1). LR diets upregulated fatty acid transport protein 4 and acetyl-coA carboxylase α expression levels and downregulated the expression level of adipose triglyceride lipase (p < 0.05). LR diets improved energy metabolism via decreasing the expression levels of AMP-activated protein kinase (AMPK) α1, sirtuin 1 (SIRT1), and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) (p < 0.05). Additionally, LR diets stimulated hepatic bile acid synthesis via upregulating the expression levels of cytochrome P450 family 7 subfamily A member 1 and cytochrome P450 family 27 subfamily A member 1, and downregulating farnesol X receptor (FXR) and small heterodimer partner (SHP) expression levels (p < 0.05). A lowered SID Lys:NE ratio affected the colonic microbial composition, characterized by increased relative abundances of YRC22, Parabacteroides, Sphaerochaeta, and Bacteroides, alongside a decreased in the proportion of Roseburia, f_Lachnospiraceae_g_Clostridium, Enterococcus, Shuttleworthia, Exiguobacterium, Corynebacterium, Subdoligranulum, Sulfurospirillum, and Marinobacter (p < 0.05). The alterations in microbial composition were accompanied by a decrease in colonic butyrate concentration (p < 0.1). The metabolomic analysis revealed that LR diets affected primary bile acid synthesis and AMPK signaling pathway (p < 0.05). And the mantel analysis indicated that Parabacteroides, Sphaerochaeta, f_Lachnospiraceae_g_Clostridium, Shuttleworthia, and Marinobacter contributed to the alterations in body metabolism. A reduced dietary SID Lys:NE ratio improves energy metabolism, stimulates lipogenesis, and inhibits lipolysis in finishing pigs by regulating the AMPKα/SIRT1/PGC-1α pathway and the FXR/SHP pathway. Parabacteroides and Sphaerochaeta benefited bile acids synthesis, whereas f_Lachnospiraceae_g_Clostridium, Shuttleworthia, and Marinobacter may contribute to the activation of the AMPK signaling pathway. Overall, body metabolism and colonic microbiota collectively controlled the lipid metabolism in finishing pigs.

Short communication: Effects of a commercial triple-strain Bacillus-based probiotic on cecal colonization with Salmonella Enteritidis in commercial layer pullets

A commercial triple-strain Bacillus-based probiotic was tested to determine its effect on the colonization of the ceca by Salmonella Enteritidis (SE) in commercial layer pullets. Two treatments were tested, each with containing 128 day-of-hatch LSL layer chicks. On top of a standard diet: 1) no supplement (Control, CON), and 2) Probiotic (GalliPro® Fit, 500 g/MT, 1.6 × 106 CFU/g of finished feed, PRO). Environmental swabs were collected from each treatment group and tested to ensure freedom from SE prior to challenge. At 21 days of age, the SE challenge strain was administered orally at a dose of 3.3 × 108 CFU/bird. Pullets from each treatment group (n=32) were euthanized at 6-, 10-, 14-, and 18-days post infection (dpi). Contents from the ceca were aseptically collected and assessed for presence and abundance of SE. No differences in the prevalence of SE positive ceca following oral inoculation (P>0.05) were observed between treatment groups at 6-, 10-, 14-, or 18-dpi. Counts of SE in the ceca of the PRO group were not significantly different (P>0.05) from those of CON at 6- or 10-dpi. However, significantly lower counts of SE in the ceca of the PRO group were observed at 14-dpi (P<0.05) and 18-dpi (P<0.05) compared with CON. SE counts were 1.24 and 1.34 logs lower than CON at 14- and 18-dpi, respectively. In conclusion, supplementation of the triple-strain Bacillus-based probiotic resulted in lower cecal counts of SE compared to those that did not receive an effective probiotic, thereby reducing the risk of foodborne pathogens prior to harvest through sustainable, natural methods.

Dust sprinkling as an effective method for infecting layer chickens with wild-type Salmonella Typhimurium and changes in host gut microbiota

Role of dust in Salmonella transmission on chicken farms is not well characterised. Salmonella Typhimurium (ST) infection of commercial layer chickens was investigated using a novel sprinkling method of chicken dust spiked with ST and the uptake compared to a conventional oral infection. While both inoculation methods resulted in colonisation of the intestines, the Salmonella load in liver samples was significantly higher at 7 dpi after exposing chicks to sprinkled dust compared to the oral infection group. Infection of chickens using the sprinkling method at a range of doses showed a threshold for colonisation of the gut and organs as low as 1000 CFU/g of dust. Caecal content microbiota analysis post-challenge showed that the profiles of chickens infected by the sprinkling and oral routes were not significantly different; however, both challenges induced differences when compared to the uninfected negative controls. Overall, the study showed that dust sprinkling was an effective way to experimentally colonise chickens with Salmonella and alter the gut microbiota than oral gavage at levels as low as 1000 CFU/g dust. This infection model mimics the field scenario of Salmonella infection in poultry sheds. The model can be used for future challenge studies for effective Salmonella control.

Battling Salmonella enteritidis infections: integrating proteomics and in vivo assessment of Galla Chinensis tannic acid

Salmonella infections pose a significant threat to animal and human health. Phytochemicals present a potential alternative treatment. Galla chinensis tannic acid (GCTA), a hydrolyzable polyphenolic compound, inhibits bacterial growth and demonstrates potential as an alternative or supplement to antibiotics to prevent Salmonella infections. However, little is known about the antimicrobial mechanism of GCTA against Salmonella. Here, we revealed 456 differentially expressed proteins upon GCTA treatment, impacting pathways related to DNA replication, repair, genomic stability, cell wall biogenesis, and lipid metabolism using TMT-labeled proteomic analysis. TEM analysis suggested altered bacterial morphology and structure post-treatment. A Salmonella-infected-mouse model indicated that GCTA administration improved inflammatory markers, alleviated intestinal histopathological alterations, and reduced Salmonella enterica serovar Enteritidis (S. Enteritidis) colonization in the liver and spleen of Salmonella-infected mice. The LD50 of GCTA was 4100 mg/kg with an oral single dose, vastly exceeding the therapeutic dose. Thus, GCTA exhibited antibacterial and anti-infective activity against S. Enteritidis. Our results provided insight into the molecular mechanisms of these antibacterial effects, and highlights the potential of GCTA as an alternative to antibiotics.

Effect of replacing soybean meal with Hermetia illucens meal on cecal microbiota, liver transcriptome, and plasma metabolome of broilers

Despite the existence of a number of studies investigating the effect of insect meal on the growth performance of broilers, knowledge about the metabolic effects of insect meal in broilers is still scarce. Thus, the present study investigated the effect of partial replacement of soybean meal with Hermetia illucens (HI) larvae meal on the liver transcriptome, the plasma metabolome, and the cecal microbiota in broilers. For the study, 72 male one-day-old Cobb 500 broilers were divided into three groups and fed 3 different diets with either 0% (HI0), 7.5% (HI7.5), or 15% (HI15) defatted HI meal for 35 d. Each group consisted of 6 cages (replicates) with 4 broilers/cage. While body weight (BW) gain, feed intake, and feed:gain ratio did not differ between groups, breast muscle weight, carcass yield, and apparent ileal digestibility (AID) of 5 amino acids were higher in group HI15 than in group HI0 (P < 0.05). Indicators of α-diversity (Chao1 and Observed) in the cecal digesta were higher in groups HI15 and HI7.5 than in group HI0 (P < 0.05). The abundance of 5 families and 18 genera, all of which belonged to the Firmicutes phylum, in the cecal digesta differed among groups (P < 0.05). Concentrations of butyric acid, valeric acid, and isobutyric acid in the cecal digesta were lower in group HI15 than in the other 2 groups (P < 0.05), whereas those of total and other short-chain fatty acids were not different between groups. Liver transcriptomics revealed a total of 70 and 61 differentially expressed transcripts between groups HI15 vs. HI0 and between groups HI7.5 vs. HI0, respectively, (P < 0.05). Targeted metabolomics identified 138 metabolites, most of which were triglyceride species, being different between the 3 groups (FDR < 0.05). According to this study, dietary inclusion of HI larvae meal has no detrimental impact but increases breast muscle weight and carcass weight in broilers suggesting that HI larvae meal can be recommended as a sustainable alternative protein source for broilers.

A live attenuated Salmonella Typhimurium vaccine dose and diluent have minimal effects on the caecal microbiota of layer chickens

Among the Salmonella reduction strategies in poultry production, one option is to use a Salmonella vaccine. The aim of vaccinating layer flocks is to reduce the shedding of wild-type Salmonella in the poultry environment, thereby reducing the contamination of poultry products (eggs and meat). Nutritive diluent and a higher dose of vaccine may enhance its colonization potential in the gut of chickens. In this study, a commercially available live attenuated vaccine (Vaxsafe® ST) was reconstituted in different media and delivered orally to day-old chicks at three different doses (107, 108, and 109 CFU/chick). Gut colonization of the vaccine strain and the effects of vaccination on gut microbiota were assessed in commercial-layer chickens. The vaccine diluent and dosage minimally affected microbiota alpha diversity. Microbiota beta diversity was significantly different (P < 0.05) based on the vaccine diluent and dose, which indicated that the vaccinated and unvaccinated chickens had different gut microbial communities. Differences were noted in the abundance of several genera, including Blautia, Colidextribacter, Dickeya, Enterococcus, Lactobacillus, Pediococcus, and Sellimonas. The abundance of Colidextribacter was significantly lower in chickens that received vaccine reconstituted in Marek's and water diluents, while Lactobacillus abundance was significantly lower in the water group. The highest vaccine dose (109 CFU/chick) did not significantly alter (P > 0.05) the abundance of microbial genera. Chicken age affected the microbiota composition more significantly than the vaccine dose and diluent. The abundance of Lactobacillus, Blautia, Caproiciproducens, Pediococcus, and Colidextribacter was significantly higher on day 14 compared with day 7 post-vaccination. The Salmonella Typhimurium vaccine load in the caeca was not significantly affected by diluent and vaccine dose; however, it was significantly lower (P < 0.0001) on day 14 compared with day 7 post-vaccination. Overall, the S. Typhimurium vaccine minimally affected the gut microbiota structure of layer chicks, whereas changes in microbiota were more significant with chicken age.

Live black soldier fly (Hermetia illucens) larvae in feed for laying hens: effects on hen gut microbiota and behavior

This study examined the effects of including live black soldier fly (BSF, Hermetia illucens) larvae in the diet of laying hens on gut microbiota, and the association between microbiota and fearfulness. A total of 40 Bovans White laying hens were individually housed and fed 1 of 4 dietary treatments that provided 0, 10, 20%, or ad libitum daily dietary portions of live BSF larvae for 12 wk. Cecum microbiota was collected at the end of the experiment and sequenced. Behavioral fear responses to novel objects and open field tests on the same hens were compared against results from gut microbiota analyses. The results showed that the bacteria genera Enterococcus, Parabacteroides, and Ruminococcus torques group were positively associated with increased dietary portion of live larvae, while Lactobacillus, Faecalibacterium, Bifidobacterium, Subdoligranulum, and Butyricicoccus were negatively associated with larvae in the diet. Inclusion of larvae did not affect fear behavior, but the relative abundance of Lachnospiraceae CHKCI001 and Erysipelatoclostridium was associated with fear-related behaviors. Further studies are needed to determine whether the change in gut microbiota affects fearfulness in the long-term.

Salmonella in eggs and egg-laying chickens: pathways to effective control

Eggs contaminated with Salmonella have been internationally significant sources of human illness for several decades. Most egg-associated illness has been attributed to Salmonella serovar Enteritidis, but a few other serovars (notably S. Heidelberg and S. Typhimurium) are also sometimes implicated. The edible interior contents of eggs typically become contaminated with S. Enteritidis because the pathogen's unique virulence attributes enable it to colonize reproductive tissues in systemically infected laying hens. Other serovars are more commonly associated with surface contamination of eggshells. Both research and field experience have demonstrated that the most effective overall Salmonella control strategy in commercial laying flocks is the application of multiple interventions throughout the egg production cycle. At the preharvest (egg production) level, intervention options of demonstrated efficacy include vaccination and gastrointestinal colonization control via treatments such as prebiotics, probiotics, and bacteriophages, Effective environmental management of housing systems used for commercial laying flocks is also essential for minimizing opportunities for the introduction, transmission, and persistence of Salmonella in laying flocks. At the postharvest (egg processing and handling) level, careful regulation of egg storage temperatures is critical for limiting Salmonella multiplication inside the interior contents.

Differential cytokine profiling and microbial species involved in cecal microbiota modulations in SPF chicks immunized with a dual vaccine against Salmonella Typhimurium infection

Salmonella Typhimurium (ST) infection in laying hens is a significant threat to public health and food safety. Host resistance against enteric pathogen invasion primarily relies on immunity and gut barrier integrity. This study applied the ST infection model and a dual live vaccine containing Salmonella Enteritidis (SE) strain Sm24/Rif12/Ssq and ST strain Nal2/Rif9/Rtt to investigate the cellular cytokine expression profiles and the differential community structure in the cecal microbiota of specific-pathogen-free (SPF) chicks and field-raised layers. The results showed that ST challenge significantly upregulated expressions of IL-1β in SPF chicks. Vaccination, on the other hand, led to an elevation in IFNγ expression and restrained IL-1β levels. In the group where vaccination preceded the ST challenge (S.STvc), heightened expressions of IL-1β, IL-6, IL-10, and IL-12β were observed, indicating active involvement of both humoral and cell-mediated immunity in the defense against ST. Regarding the cecal microbiota, the vaccine did not affect alpha diversity nor induce a significant shift in the microbial community. Conversely, ST infection significantly affected the alpha and beta diversity in the cecal microbiota, reducing beneficial commensal genera, such as Blautia and Subdoligranulum. MetagenomeSeq analysis reveals a significant increase in the relative abundance of Faecalibacterium prausnitzii in the groups (S.STvc and STvc) exhibiting protection against ST infection. LEfSe further demonstrated Faecalibacterium prausnitzii as the prominent biomarker within the cecal microbiota of SPF chicks and field layers demonstrating protection. Another biomarker identified in the S.STvc group, Eubacterium coprostanoligenes, displayed an antagonistic relationship with Faecalibacterium prausnitzii, suggesting the limited biological significance of the former in reducing cloacal shedding and tissue invasion. In conclusion, the application of AviPro Salmonella DUO vaccine stimulates host immunity and modulates cecal microbiota to defend against ST infection. Among the microbial modulations observed in SPF chicks and field layers with protection, Faecalibacterium prausnitzii emerges as a significant species in the ceca. Further research is warranted to elucidate its role in protecting layers against ST infection.

The improvement of immunity and activation of TLR2/NF-κB signaling pathway by Romboutsia ilealis in broilers

This study was conducted to investigate the effects of Romboutsia ilealis on the immune function of broilers and the underlying mechanisms. A total of 48 one-day-old Arbor Acres broilers were allocated to 4 groups as follows: broilers treated daily with 1 mL live R. ilealis in general anaerobic medium broth media (0, 1 × 104, 1 × 106, and 1 × 108 CFU/mL) from days 1 to 7. Samples were collected on days 8 and 14. The results showed that R. ilealis had no negative effect on the body weight of broilers (P > 0.05). R. ilealis significantly increased the levels of lysozyme, IFN-γ, IFN-γ/IL-4, and IgG in the serum (P < 0.05). R. ilealis significantly increased the levels of IL-4, IFN-γ, sIgA, lysozyme, and iNOS in the ileal mucosa (P < 0.05). R. ilealis significantly increased the mRNA levels of TLR2, TLR4, NF-κB, IL-1β, TNF-α, IFN-γ, IgA, pIgR, iNOS, and MHC-II in the ileum (P < 0.05). R. ilealis significantly increased the relative abundance of Enterococcus and Paracoccus in the jejunum and ileum, ileal Candidatus Arthromitus, and cecal Romboutsia and Intestinimonas (P < 0.05). Correlation analysis showed that Enterococcus, Paracoccus, Romboutsia, and Intestinimonas were significantly positively correlated with humoral immune function (P < 0.05). In conclusion, R. ilealis boosted the immune system, activated the intestinal TLR2/NF-κB signaling pathway, and improved the gut microbiota in broilers.

Selection and evaluation of lactic acid bacteria from chicken feces in Thailand as potential probiotics

Background

Lactic acid bacteria (LAB) are widely used as probiotics in poultry production due to their resilience to low pH and high bile salt concentrations, as well as their beneficial effects on growth performance and antagonistic activity against enteric pathogens. However, the efficacy of probiotics depends on strain selection and their ability to colonize the host's intestine. This study aimed to select, identify, and evaluate LAB strains isolated from chicken feces in Thailand for potential use as probiotics in the chicken industry.

Methods

LAB strains were isolated from 58 pooled fresh fecal samples collected from chicken farms in various regions of Thailand, including commercial and backyard farms. Gram-positive rods or cocci with catalase-negative characteristics from colonies showing a clear zone on MRS agar supplemented with 0.5% CaCO3 were identified using MALDI-TOF mass spectrometry. The LAB isolates were evaluated for acid (pH 2.5 and pH 4.5) and bile salt (0.3% and 0.7%) tolerance. Additionally, their cell surface properties, resistance to phenol, antimicrobial activity, hemolytic activity, and presence of antimicrobial resistance genes were determined.

Results

A total of 91 LAB isolates belonging to the Pediococcus, Ligilactobacillus, Limosilactobacillus, and Lactobacillus genera were obtained from chicken feces samples. Backyard farm feces exhibited a greater LAB diversity compared to commercial chickens. Five strains, including Ligilactobacillus salivarius BF12 and Pediococcus acidilactici BF9, BF14, BYF20, and BYF26, were selected based on their high tolerance to acid, bile salts, and phenol. L. salivarius BF12 and P. acidilactici BF14 demonstrated strong adhesion ability. The five LAB isolates exhibited significant cell-cell interactions (auto-aggregation) and co-aggregation with Salmonella. All five LAB isolates showed varying degrees of antimicrobial activity against Salmonella strains, with P. acidilactici BYF20 displaying the highest activity. None of the LAB isolates exhibited beta-hemolytic activity. Whole genome analysis showed that L. salivarius BF12 contained ermC, tetL, and tetM, whereas P. acidilactici strains BF9 and BF14 carried ermB, lnuA, and tetM.

Conclusion

The selected LAB isolates exhibited basic probiotic characteristics, although some limitations were observed in terms of adhesion ability and the presence of antibiotic resistance genes, requiring further investigation into their genetic location. Future studies will focus on developing a probiotic prototype encapsulation for application in the chicken industry, followed by in vivo evaluations of probiotic efficacy.

Salmonella Infection in Poultry: A Review on the Pathogen and Control Strategies

Salmonella is the leading cause of food-borne zoonotic disease worldwide. Non-typhoidal Salmonella serotypes are the primary etiological agents associated with salmonellosis in poultry. Contaminated poultry eggs and meat products are the major sources of human Salmonella infection. Horizontal and vertical transmission are the primary routes of infection in chickens. The principal virulence genes linked to Salmonella pathogenesis in poultry are located in Salmonella pathogenicity islands 1 and 2 (SPI-1 and SPI-2). Cell-mediated and humoral immune responses are involved in the defense against Salmonella invasion in poultry. Vaccination of chickens and supplementation of feed additives like prebiotics, probiotics, postbiotics, synbiotics, and bacteriophages are currently being used to mitigate the Salmonella load in poultry. Despite the existence of various control measures, there is still a need for a broad, safe, and well-defined strategy that can confer long-term protection from Salmonella in poultry flocks. This review examines the current knowledge on the etiology, transmission, cell wall structure, nomenclature, pathogenesis, immune response, and efficacy of preventative approaches to Salmonella.

The protective effects of Bacillus licheniformis against inflammatory responses and intestinal barrier damage in broilers with necrotic enteritis induced by Clostridium perfringens

BACKGROUND

Bacillus licheniformis is a gram-positive bacterium that has strong environmental adaptability and can improve the growth performance, immunity, and antioxidant function of broilers. The current study aimed to elucidate the protective capability of B. licheniformis against inflammatory responses and intestinal barrier damage in broilers with necrotic enteritis (NE) induced by Clostridium perfringens (CP).

RESULTS

The results showed that B. licheniformis enhanced the final body weight in broilers compared with that of broilers in the CP group after the stress of infection (P < 0.05). Bacillus licheniformis reversed the decreased levels of serum and jejunum mucosa immunoglobulins and anti-inflammatory cytokines, reduced the values of villus height and the ratio of villus height to crypt depth, and mitigated the increased levels of serum d-lactic acid and diamine oxidase in CP-challenged broilers (P < 0.05). Moreover, B. licheniformis modulated the expression levels of genes involved in the TLR4/NF-κB signalling pathway, the NLRP3 inflammasome activation pathway, and the sirt 1/Parkin signalling pathway in CP-challenged broilers. Compared with the CP challenge group, the B. licheniformis-treated group exhibited reduced abundance values of Shuttleworthia and Alistipes and enhanced abundance values of Parabacteroides in the caecal contents (P < 0.05).

CONCLUSION

Bacillus licheniformis improved the final body weight and alleviated the inflammatory response and intestinal barrier function damage in birds with NE induced by CP by maintaining intestinal physiological function, enhancing immunity, regulating inflammatory cytokine secretion, modulating the mitophagy response, and increasing the abundance of beneficial intestinal flora. © 2023 Society of Chemical Industry.

Modulation of Caecal Microbiota and Metabolome Profile in Salmonella-Infected Broilers by Phage Therapy

Bacteriophage therapy is considered one of the most promising tools to control zoonotic bacteria, such as Salmonella, in broiler production. Phages exhibit high specificity for their targeted bacterial hosts, causing minimal disruption to the niche microbiota. However, data on the gut environment's response to phage therapy in poultry are limited. This study investigated the influence of Salmonella phage on host physiology through caecal microbiota and metabolome modulation using high-throughput 16S rRNA gene sequencing and an untargeted metabolomics approach. We employed 24 caecum content samples and 24 blood serum samples from 4-, 5- and 6-week-old broilers from a previous study where Salmonella phages were administered via feed in Salmonella-infected broilers, which were individually weighed weekly. Phage therapy did not affect the alpha or beta diversity of the microbiota. Specifically, we observed changes in the relative abundance of 14 out of the 110 genera using the PLS-DA and Bayes approaches. On the other hand, we noted changes in the caecal metabolites (63 up-accumulated and 37 down-accumulated out of the 1113 caecal metabolites). Nevertheless, the minimal changes in blood serum suggest a non-significant physiological response. The application of Salmonella phages under production conditions modulates the caecal microbiome and metabolome profiles in broilers without impacting the host physiology in terms of growth performance.

Phenotype Alterations in the Cecal Ecosystem Involved in the Asymptomatic Intestinal Persistence of Paratyphoid Salmonella in Chickens

The gastrointestinal ecosystem involves interactions between the host, gut microbiota, and external environment. To colonize the gut of poultry, Salmonella must surmount barriers levied by the intestine including mucosal innate immune responses and microbiota-mediated niche restrictions. Accordingly, comprehending Salmonella intestinal colonization in poultry requires an understanding of how the pathogen interacts with the intestinal ecosystem. In chickens, the paratyphoid Salmonella have evolved the capacity to survive the initial immune response and persist in the avian ceca for months without triggering clinical signs. The persistence of a Salmonella infection in the avian host involves both host defenses and tolerogenic defense strategies. The initial phase of the Salmonella-gut ecosystem interaction is characteristically an innate pro-inflammatory response that controls bacterial invasion. The second phase is initiated by an expansion of the T regulatory cell population in the cecum of Salmonella-infected chickens accompanied by well-defined shifts in the enteric neuro-immunometabolic pathways that changes the local phenotype from pro-inflammatory to an anti-inflammatory environment. Thus, paratyphoid Salmonella in chickens have evolved a unique survival strategy that minimizes the inflammatory response (disease resistance) during the initial infection and then induces an immunometabolic reprogramming in the cecum that alters the host defense to disease tolerance that provides an environment conducive to drive asymptomatic carriage of the bacterial pathogen.

Influence of Live Attenuated Salmonella Vaccines on Cecal Microbiome Composition and Microbiota Abundances in Young Broiler Chickens

Salmonellosis is a global food safety challenge caused by Salmonella, a gram-negative bacterium of zoonotic importance. Poultry is considered a major reservoir for the pathogen, and humans are exposed through consumption of raw or undercooked products derived from them. Prophylaxis of Salmonella in poultry farms generally mainly involves biosecurity measures, flock testing and culling, use of antibiotics, and vaccination programs. For decades, the use of antibiotics has been a common practice to limit poultry contamination with important pathogenic bacteria such as Salmonella at the farm level. However, due to an increasing prevalence of resistance, non-therapeutic use of antibiotics in animal production has been banned in many parts of the world. This has prompted the search for non-antimicrobial alternatives. Live vaccines are among the developed and currently used methods for Salmonella control. However, their mechanism of action, particularly the effect they might have on commensal gut microbiota, is not well understood. In this study, three different commercial live attenuated Salmonella vaccines (AviPro^® Salmonella Vac T, AviPro^® Salmonella DUO, and AviPro^® Salmonella Vac E) were used to orally vaccinate broiler chickens, and cecal contents were collected for microbiomes analysis by 16S rRNA next generation sequencing. Quantitative real-time PCR (qPCR) was used to study the cecal immune-related genes expression in the treatment groups, while Salmonella-specific antibodies were analyzed from sera and cecal extracts by enzyme-linked immunosorbent assay (ELISA). We show that vaccination with live attenuated Salmonella vaccines had a significant influence on the variability of the broiler cecal microbiota (p = 0.016). Furthermore, the vaccines AviPro^® Salmonella Vac T and AviPro^® Salmonella DUO, but not AviPro^® Salmonella Vac E, had a significant effect (p = 0.024) on microbiota composition. This suggests that the live vaccine type used can differently alter the microbiota profiles, driving the gut colonization resistance and immune responses to pathogenic bacteria, and might impact the overall chicken health and productivity. Further investigation is, however, required to confirm this.

Restorative effects of Lactobacillus rhamnosus LR-32 on the gut microbiota, barrier integrity, and 5-HT metabolism in reducing feather-pecking behavior in laying hens with antibiotic-induced dysbiosis

The development of abnormal feather-pecking (FP) behavior, where laying hens display harmful pecks in conspecifics, is multifactorial and has been linked to the microbiota-gut-brain axis. Antibiotics affect the gut microbial composition, leading to gut-brain axis imbalance and behavior and physiology changes in many species. However, it is not clear whether intestinal dysbacteriosis can induce the development of damaging behavior, such as FP. The restorative effects of Lactobacillus rhamnosus LR-32 against intestinal dysbacteriosis-induced alternations need to be determined either. The current investigation aimed to induce intestinal dysbacteriosis in laying hens by supplementing their diet with the antibiotic lincomycin hydrochloride. The study revealed that antibiotic exposure resulted in decreased egg production performance and an increased tendency toward severe feather-pecking (SFP) behavior in laying hens. Moreover, intestinal and blood-brain barrier functions were impaired, and 5-HT metabolism was inhibited. However, treatment with Lactobacillus rhamnosus LR-32 following antibiotic exposure significantly alleviated the decline in egg production performance and reduced SFP behavior. Lactobacillus rhamnosus LR-32 supplementation restored the profile of the gut microbial community, and showed a strong positive effect by increasing the expression of tight junction proteins in the ileum and hypothalamus and promoting the expression of genes related to central 5-HT metabolism. The correlation analysis revealed that probiotic-enhanced bacteria were positively correlated, and probiotic-reduced bacteria were negatively correlated with tight junction-related gene expression, and 5-HT metabolism, and butyric acid levels. Overall, our findings indicate that dietary supplementation with Lactobacillus rhamnosus LR-32 can reduce antibiotic-induced FP in laying hens and is a promising treatment to improve the welfare of domestic birds.

Antimicrobial Drug Resistance in Poultry Production: Current Status and Innovative Strategies for Bacterial Control

The world population’s significant increase has promoted a higher consumption of poultry products, which must meet the specified demand while maintaining their quality and safety. It is well known that conventional antimicrobials (antibiotics) have been used in livestock production, including poultry, as a preventive measure against or for the treatment of infectious bacterial diseases. Unfortunately, the use and misuse of these compounds has led to the development and dissemination of antimicrobial drug resistance, which is currently a serious public health concern. Multidrug-resistant bacteria are on the rise, being responsible for serious infections in humans and animals; hence, the goal of this review is to discuss the consequences of antimicrobial drug resistance in poultry production, focusing on the current status of this agroeconomic sector. Novel bacterial control strategies under investigation for application in this industry are also described. These innovative approaches include antimicrobial peptides, bacteriophages, probiotics and nanoparticles. Challenges related to the application of these methods are also discussed.

Application of Eugenol in Poultry to Control Salmonella Colonization and Spread

The poultry sector is an essential component of agriculture that has experienced unprecedented growth during the last few decades. It is especially true for the United States, where the average intake of chicken meat increased from 10 pounds (4.5 kg) per person in 1940 to 65.2 pounds (29.6 kg) per person in 2018, while the country produced 113 billion eggs in 2019 alone. Besides providing nutrition and contributing significantly to the economy, chicken is also a natural reservoir of Salmonella, which is responsible for salmonellosis in humans, one of the significant foodborne illnesses around the globe. The increasing use of chicken manure and antibiotics increases the spread of Salmonella and selects for multi-drug resistant strains. Various plant extracts, primarily essential oils, have been investigated for their antimicrobial activities. The multiple ways through which these plant-derived compounds exert their antimicrobial effects make the development of resistance against them unlikely. Eugenol, an aromatic oil primarily found in clove and cinnamon, has shown antimicrobial activities against various pathogenic bacteria. A few reports have also highlighted the anti-Salmonella effects of eugenol in chicken, especially in reducing the colonization by Salmonella Enteritidis and Salmonella Typhimurium, the primary Salmonella species responsible for human salmonellosis. Besides limiting Salmonella infection in chicken, the supplementation of eugenol also significantly improves intestinal health, improving overall well-being. In this review, we highlight the rising incidences of salmonellosis worldwide and the factors increasing its prevalence. We then propose the usage of eugenol as a natural feed supplement for containing Salmonella in chicken.

Low Ca diet leads to increased Ca retention by changing the gut flora and ileal pH value in laying hens

Osteoporosis is a common degenerative metabolic bone disease in caged laying hens. Intensive egg production mobilizing large amounts of Ca from bone for eggshell formation, consequently leading to Ca deficiency, has been recognized as a critical factor causing osteoporosis in commercial laying hens. The aim of this study was to examine the effect of Ca deficiency on the function of the gut microbiota-bone axis and related egg production traits and bone health in laying hens. Twenty-four 48-week-old laying hens were fed a control diet (Control, 3.72%) or a low Ca diet (LC, 2.04%) for 60 d (n = 12). Compared to the Control hens, the LC hens had higher levels of alkaline phosphatase and tartrate resistant acid phosphatase (P < 0.05) with lower bone strength, eggshell thickness, and eggshell strength (P < 0.05). In addition, the LC hens had higher plasma estradiol concentrations, while having lower concentrations of interleukin-1 (IL-1) and IL-6. The LC hens also had a lower pH value in the ileum with an increased Ca retention. The principal co-ordinates analysis showed significantly separate cecal microbiota populations between the Control and LC hens. The Prevotellaceae_UCG-001, Subdoligranulum, Peptococcus, and Eubacterium_hallii_group (P < 0.05) were higher, while the CHKC1001 and Sutterella (P < 0.05) were lower at the genus level in the LC hens. In addition, Prevotellaceae_UCG-001, Subdoligranulum and Eubacterium_hallii_group had a negative correlation, while Sutterella was positively correlated with ileal pH values. The transcriptome analysis revealed that the low Ca diet caused 20 and 31 genes to be significantly up- and down-regulated, respectively. The gene expressions of cystic fibrosis transmembrane conductance regulator, solute carrier family 26 member 3 of the anion exchangers, and mitogen-activated protein kinase 12 of pro-inflammatory factors were lower in the LC birds, which was correlated with the lower ileal pH values. These results suggest that the hens with low Ca diet-induced osteoporosis have an increased intestinal Ca retention with a decreased ileal pH value, correlated with the changes in Prevotellaceae_UCG-001, Subdoligranulum, and Eubacterium_hallii_group of beneficial genera. The results provide insights for further understanding and preventing osteoporosis in laying hens.

Effects of lysophospholipids and multi-enzymes on growth performance, antioxidant capacity, intestinal health, and cecal microflora of male cherry valley ducks

Improvement of nutrient utilization to promote growth performance is always pursued in poultry. In this study, a total of 360 1-d-old male ducklings was randomly assigned to 3 treatments in terms of diet treatment groups. Three treatments were as follows: basal diet (Con group) or basal diet supplemented with 300 mg/kg multi-enzymes (ENZ group) or 500 mg/kg lysophospholipids (LPL group). On day 42, ducks were slaughtered for samplings. The results revealed that supplementary LPL improved the body weight (BW) at day 14 and average daily gain (ADG) during days 1 to 14 and improved the feed conversion rate (FCR) for the overall period (P < 0.05) by improving nutrient utilization of dry matter and ether extract (P < 0.05) compared with the Con group. Dietary ENZ improved the FCR from days 15-42 and 1-42, and nitrogen utilization (P < 0.05) compared with the Con group. Jejunal villus height and villus height/crypt depth ratio were higher (P < 0.05) in the LPL group and tended to be higher (P < 0.1) in the ENZ group compared to the Con group. Supplementation with either LPL or ENZ reduced interleukin-1β concentration in jejunal mucus (P < 0.05). Both LPL and ENZ enhanced serum total superoxide dismutase activity (P < 0.05), whereas only supplementation with LPL elevated total antioxidant capacity (P < 0.05). In terms of cecal microbiota, microbial richness tended to be reduced by LPL, with low observed-OTUs and Chao1 (0.05 < P < 0.1). Supplementation with ENZ led to higher abundances of cellulolytic bacteria such as Fibrobacterota, [Eubacterium]_xylanophilum_group, and Bifidobacterium. Overall, both LPL and ENZ improved FCR, which may be relevant to ameliorative intestinal health, overall antioxidant ability, and cecal microbiome.

In Vitro and In Vivo Evaluation of Lacticaseibacillus rhamnosus GG and Bifidobacterium lactis Bb12 Against Avian Pathogenic Escherichia coli and Identification of Novel Probiotic-Derived Bioactive Peptides

Avian pathogenic E. coli (APEC), an extra-intestinal pathogenic E. coli (ExPEC), causes colibacillosis in poultry and is also a potential foodborne zoonotic pathogen. Currently, APEC infections in poultry are controlled by antibiotic medication; however, the emergence of multi-drug-resistant APEC strains and increased restrictions on the use of antibiotics in food-producing animals necessitate the development of new antibiotic alternative therapies. Here, we tested the anti-APEC activity of multiple commensal and probiotic bacteria in an agar-well diffusion assay and identified Lacticaseibacillus rhamnosus GG and Bifidobacterium lactis Bb12 producing strong zone of inhibition against APEC. In co-culture assay, L. rhamnosus GG and B. lactis Bb12 completely inhibited the APEC growth by 24 h. Further investigation revealed that antibacterial product(s) in the culture supernatants of L. rhamnosus GG and B. lactis Bb12 were responsible for the anti-APEC activity. The analysis of culture supernatants using LC-MS/MS identified multiple novel bioactive peptides (VQAAQAGDTKPIEV, AFDNTDTSLDSTFKSA, VTDTSGKAGTTKISNV, and AESSDTNLVNAKAA) in addition to the production of lactic acid. The oral administration (10⁸ CFU/chicken) of L. rhamnosus GG significantly (P < 0.001) reduced the colonization (~ 1.6 logs) of APEC in the cecum of chickens. Cecal microbiota analysis revealed that L. rhamnosus GG moderated the APEC-induced alterations of the microbial community in the cecum of chickens. Further, L. rhamnosus GG decreased (P < 0.05) the abundance of phylum Proteobacteria, particularly those belonging to Enterobacteriaceae (Escherichia-Shigella) family. These studies indicate that L. rhamnosus GG is a promising probiotic to control APEC infections in chickens. Further studies are needed to optimize the delivery of L. rhamnosus GG in feed or water and in conditions simulating the field to facilitate its development for commercial applications.

Age matters: Microbiome depletion prior to repeat mild traumatic brain injury differentially alters microbial composition and function in adolescent and adult rats

Dysregulation of the gut microbiome has been shown to perpetuate neuroinflammation, alter intestinal permeability, and modify repetitive mild traumatic brain injury (RmTBI)-induced deficits. However, there have been no investigations regarding the comparative effects that the microbiome may have on RmTBI in adolescents and adults. Therefore, we examined the influence of microbiome depletion prior to RmTBI on microbial composition and metabolome, in adolescent and adult Sprague Dawley rats. Rats were randomly assigned to standard or antibiotic drinking water for 14 days, and to subsequent sham or RmTBIs. The gut microbiome composition and metabolome were analysed at baseline, 1 day after the first mTBI, and at euthanasia (11 days following the third mTBI). At euthanasia, intestinal samples were also collected to quantify tight junction protein (TJP1 and occludin) expression. Adolescents were significantly more susceptible to microbiome depletion via antibiotic administration which increased pro-inflammatory composition and metabolites. Furthermore, RmTBI induced a transient increase in 'beneficial bacteria' (Lachnospiraceae and Faecalibaculum) in only adolescents that may indicate compensatory action in response to the injury. Finally, microbiome depletion prior to RmTBI generated a microbiome composition and metabolome that exemplified a potentially chronic pathogenic and inflammatory state as demonstrated by increased Clostridium innocuum and Erysipelatoclostridium and reductions in Bacteroides and Clostridium Sensu Stricto. Results highlight that adolescents are more vulnerable to RmTBI compared to adults and dysbiosis prior to injury may exacerbate secondary inflammatory cascades.

Bacteroides fragilis derived metabolites, identified by molecular networking, decrease Salmonella virulence in mice model

In the gut microbiota, resident bacteria prevent pathogens infection by producing specific metabolites. Among bacteria belonging to phylum Bacteroidota, we have previously shown that Bacteroides fragilis or its cell-free supernatant inhibited in vitro Salmonella Heidelberg translocation. In the present study, we have analyzed this supernatant to identify bioactive molecules after extraction and subsequent fractionation using a semi-preparative reversed-phase Liquid Chromatography High-Resolution Tandem Mass Spectrometry (LC-HRMS/MS). The results indicated that only two fractions (F3 and F4) strongly inhibited S. Heidelberg translocation in a model mimicking the intestinal epithelium. The efficiency of the bioactive fractions was evaluated in BALB/c mice, and the results showed a decrease of S. Heidelberg in Peyer’s patches and spleen, associated with a decrease in inflammatory cytokines and neutrophils infiltration. The reduction of the genus Alistipes in mice receiving the fractions could be related to the anti-inflammatory effects of bioactive fractions. Furthermore, these bioactive fractions did not alter the gut microbiota diversity in mice. To further characterize the compounds present in these bioactive fractions, Liquid Chromatography High-Resolution Tandem Mass Spectrometry (LC-HRMS/MS) data were analyzed through molecular networking, highlighting cholic acid (CA) and deoxycholic acid. In vitro, CA had inhibitory activity against the translocation of S. Heidelberg by significantly decreasing the expression of Salmonella virulence genes such as sipA. The bioactive fractions also significantly downregulated the flagellar gene fliC, suggesting the involvement of other active molecules. This study showed the interest to characterize better the metabolites produced by B. fragilis to make them means of fighting pathogenic bacteria by targeting their virulence factor without modifying the gut microbiota.

Intracellular autolytic whole cell Salmonella vaccine prevents colonization of pathogenic Salmonella Typhimurium in chicken

Salmonella enterica (SE) is a major foodborne bacterial pathogen in the United States, commonly found as the normal flora of various animals that is attributed to causing at least 1.2 million infections annually. Poultry plays a major role in disseminating SE through direct contact with live animals and consumption of contaminated products. Vaccinating poultry against SE is a sustainable approach that can reduce SE in the host, preventing future infections in humans. An intracellular autolytic SE serovar Typhimurium vaccine (STLT2^+P13+19) was developed by integrating genes 13 (holin) and 19 (lysozyme) of bacteriophage P22 into the bacterial chromosome. These were inserted downstream of sseA, an SPI-2 chaperone in SE that expresses during the intracellular phase of SE. Intracellular viability of STLT2^+P13+19 reduced by 94.42% at 24 hr compared to the wild type in chicken macrophage cells (HD-11), whereas growth rate and adhesion ability remained unchanged. Inoculating STLT2^+P13+19 in HD-11 significantly enhanced the relative log fold expression of genes associated to production of pro-inflammatory cytokines (IL-1β, IL-6, IL-8, IL-10, IL-12 p40, IL-18, and GM-CSF) and Toll-like-receptors (TRL-3 and 7). Vaccination of an in vivo chicken model demonstrated significant changes in secretion of iNOS, IL-6, IL-8, IL-12, and TNF-α, as well as a reduction in the intestinal colonization of SE serovar Typhimurium. Microbiome analysis of cecal fluid using 16S rRNA gene sequencing also showed modulation of intestinal microbial composition, specifically a decrease in relative abundance of Proteobacteria and increasing Firmicutes. This study provides insight into a novel vaccine design that could make food products safer without the use of synthetic compounds.

The intervention effect of Amygdalus mongolica oil on the metabolomics and intestinal flora in pulmonary fibrosis

Amygdalus mongolica oil is rich in unsaturated fatty acids such as inoleic acid (47.11%) and oleic acid (23.81%). Our research demonstrates that it exerts a protective effect on rat models of pulmonary fibrosis, however, little is known regarding the underlying mechanism of action. This study aimed to characterize the therapeutic mechanism of action of A. mongolica oil on bleomycin-induced pulmonary fibrosis in rats. A. mongolica oil appears to regulate the levels of potential key serum biomarkers which include tetrahydrobiopterin, L-serine, citrulline and estradiol to participate in folate biosynthesis, glycine, serine and threonine metabolism, arginine biosynthesis and steroid hormone biosynthesis. And it also enriched intestinal microbial abundance, homogeneity and modulated the abundance of Duncaniell, Desulfovibrio, Peptococcaceae_unclassified, Dubosiella, Tyzzerella, Lachnospiraceae_NK4A136_group, Lactobacillus, Clostridiales_unclassified to exert a protective effect against pulmonary fibrosis. A. mongolica oil appears to confer protective effects against pulmonary fibrosis by affecting the level of pulmonary fibrosis metabolites and the abundance of related intestinal flora through multiple targets, as evidenced by our untargeted LC-MS/MS metabonomics evaluation and 16S rDNA sequencing technology.

Spotty liver disease adversely affect the gut microbiota of layers hen

Spotty Liver Disease (SLD) is a serious infectious disease which occurs mainly in laying chickens in free range production systems. SLD outbreaks can increase mortality and decrease egg production of chickens, adversely impact welfare and cause economic hardship for poultry producers. The bacterium Campylobacter hepaticus is the primary cause of the disease. This study aimed to identify the effects of C. hepaticus on chicken gut microbiota and gut structure. Three C. hepaticus strains (HV10^T, NSW44L and QLD19L), isolated from different states of Australia, were used in the study. Chickens at 26-weeks post-hatch were orally dosed with one of the C. hepaticus strains (challenged groups) or Brucella broth (unchallenged or control group). Six days after the challenge, birds were necropsied to assess liver damage, and caecal content and tissue samples were collected for histology, microbiology, and 16S rRNA gene amplicon sequencing to characterize the composition of the bacterial microbiota. Strain C. hepaticus NSW44L produced significantly more disease compared to the other C. hepaticus strains and this coincided with more adverse changes observed in the caecal microbiota of the birds challenged with this strain compared to the control group. Microbial diversity determined by Shannon and Simpson alpha diversity indices was lower in the NSW44L challenged groups compared to the control group (p = 0.009 and 0.0233 respectively, at genus level). Short-chain fatty acids (SCFAs) producing bacteria Faecalibacterium, Bifidobacterium and Megamonas were significantly reduced in the challenged groups compared to the unchallenged control group. Although SLD-induction affected the gut microbiota of chickens, their small intestine morphology was not noticeably affected as there were no significant differences in the villus height or ratio of villus height and crypt depth. As gut health plays a pivotal role in the overall health and productivity of chickens, approaches to improve the gut health of the birds during SLD outbreaks such as through diet and keeping the causes of stress to a minimum, may represent significant ways to alleviate the impact of SLD.

Long-term chemically protected sodium butyrate supplementation in broilers as an antibiotic alternative to dynamically modulate gut microbiota

Chemically protected sodium butyrate (CSB) is a new kind of sodium butyrate. Our previous study found that 1,000 mg/kg of CSB had the potential capacity of improving growth performance and promoting early development of small intestine in broilers. This study aimed to investigate the effect of long-term antibiotics or CSB supplementation for intestinal microflora dynamical regulation in broilers. One hundred ninety-two 1-day-old Arbor Acres male broilers were randomly allocated into 3 dietary treatment (8 replicates per treatment) and fed with a basal diet (CON), a diet supplemented with the antibiotics (enramycin, 8 mg/kg and aureomycin, 100 mg/kg) (ANT), or a diet supplemented with 1,000 mg/kg of CSB, respectively. Results showed that dietary supplementation of CSB or ANT treatment elevated the weight gain and feed conversion ratio (FCR; P < 0.05), as compared with control (CON) group. Additionally, CON, CSB, or ANT administration dynamically altered the gut microbiota composition as time goes on. The increased presence of potential pathogens, such as Romboutsia and Shuttleworthia, and decreased beneficial bacteria such as Alistipes, Akkermansia, and Bacteroides were verified in new gut homeostasis reshaped by long-term antibiotics treatment, which has adverse effects on intestinal development and health of broilers. Conversely, CSB supplementation could dynamically enhance the relative abundance of Bacteroides, and decrease Romboutsia and Shuttleworthia in new microflora, which has positive effects on intestinal bacteria of broilers compared with CON group. Meanwhile, CSB supplementation was significantly increased the concentration of propionic acid and total short chain fatty acids (total SCFA; P < 0.05) in comparison with CON and ANT groups. Moreover, CSB treatment significantly increased anti-inflammatory and antioxidative capacities (P < 0.05) of broilers compared with ANT group. Taken together, we revealed characteristic structural changes of gut microbiota throughout long-term CSB or ANT supplementation in broilers, which provided a basic data for evaluating the mechanism of action affecting intestinal health by CSB or ANT administration and CSB as an alternative to antibiotics in the broilers industry.

Physicochemical characteristics of Ganoderma lucidum oligosaccharide and its regulatory effect on intestinal flora in vitro fermentation

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G. lucidum oligosaccharide was obtained by ultrasonic enzymatic hydrolysis and Sephadex G25.

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GLO was a chain-like homogeneous oligosaccharide with a molecular weight of 1280 Da.

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GLO could not be easily degraded by digestion in the mouth, gastric and small intestine.

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GLO could be utilized and had good regulatory effects on intestinal flora.

This study explored the structure characteristics of an oligosaccharide from Ganoderma lucidum (GLO) and its regulatory functions on intestinal flora fermentation in vitro. GLO was extracted by ultrasonic-assisted enzymatic hydrolysis, and purified with a dextran gel column. Digestion properties and intestinal flora regulation effects of GLO were investigated by both simulation models. Results showed that GLO was a chain-like homogeneous oligosaccharide, composed of → 6)-β-d-Glcp-(1→, →4)-α-d-Glcp-(1→, β-d-Glcp-(1→, α-d-Manp-(1 →. Its structure could not be easily degraded by digestion in the mouth, gastric and small intestine. Accordingly, they can be utilized by the intestinal flora in large intestine. By evaluating the gas, short chain fatty acids, pH and flora abundance in vitro fermentation, it indicated that GLO had good regulatory effects on intestinal flora. Accordingly, GLO might be a potential prebiotic applied in functional foods.

Effect of Probiotic E. coli Nissle 1917 Supplementation on the Growth Performance, Immune Responses, Intestinal Morphology, and Gut Microbes of Campylobacter jejuni Infected Chickens

Campylobacter jejuni is the most common cause of bacterial foodborne gastroenteritis and holds significant public health importance. The continuing increase of antibiotic-resistant Campylobacter necessitates the development of antibiotic-alternative approaches to control infections in poultry and in humans. Here, we assessed the ability of E. coli Nissle 1917 (EcN; free and chitosan-alginate microencapsulated) to reduce C. jejuni colonization in chickens and measured the effect of EcN on the immune responses, intestinal morphology, and gut microbes of chickens. Our results showed that the supplementation of 3-week-old chickens daily with free EcN in drinking water resulted in a 2.0 log reduction of C. jejuni colonization in the cecum, whereas supplementing EcN orally three times a week, either free or microencapsulated, resulted in 2.0 and 2.5 log reductions of C. jejuni colonization, respectively. Gavaged free and microencapsulated EcN did not have an impact on the evenness or the richness of the cecal microbiota, but it did increase the villous height (VH), crypt depth (CD), and VH:CD ratio in the jejunum and ileum of chickens. Further, the supplementation of EcN (all types) increased C. jejuni-specific and total IgA and IgY antibodies in chicken’s serum. Microencapsulated EcN induced the expression of several cytokines and chemokines (1.6 to 4.3-fold), which activate the Th1, Th2, and Th17 pathways. Overall, microencapsulated EcN displayed promising effects as a potential nonantibiotic strategy to control C. jejuni colonization in chickens. Future studies on testing microencapsulated EcN in the feed and water of chickens raised on built-up floor litter would facilitate the development of EcN for industrial applications to control Campylobacter infections in poultry.

Lacticaseibacillus rhamnosus alleviates intestinal inflammation and promotes microbiota-mediated protection against Salmonella fatal infections

The fatal impairment of the intestinal mucosal barrier of chicks caused by Salmonella significantly resulting economic losses in the modern poultry industry. Probiotics are recognized for beneficially influencing host immune responses, promoting maintenance of intestinal epithelial integrity, antagonistic activity against pathogenic microorganisms and health-promoting properties. Some basic studies attest to probiotic capabilities and show that Lacticaseibacillus rhamnosus could protect intestinal mucosa from injury in animals infected with Salmonella Typhimurium. However, the mechanisms underlying its protective effects in chicks are still not fully understood. Here, we used the chick infection model combined with histological, immunological, and molecular approaches to address this question. The results indicated that L. rhamnosus significantly reduced the diarrhea rate and increased the daily weight gain and survival rate of chicks infected with S. Typhimurium. Furthermore, we found that L. rhamnosus markedly improved the immunity of gut mucosa by reducing apoptotic cells, hence effectively inhibiting intestinal inflammation. Notably, pre-treatment chicks with L. rhamnosus balanced the expression of interleukin-1β and interleukin-18, moderated endotoxin and D-lactic acid levels, and expanded tight junction protein levels (Zonula occluden-1 and Claudin-1), enhanced the function of the intestinal mucosal epithelial cells. Additionally, investigations using full-length 16S rRNA sequencing also demonstrated that L. rhamnosus greatly weakened the adhesion of Salmonella, the mainly manifestation is the improvement of the diversity of intestinal microbiota in infected chicks. Collectively, these results showed the application of L. rhamnosus against Salmonella fatal infection by enhancing barrier integrity and the stability of the gut microbiota and reducing inflammation in new hatch chicks, offering new antibiotic alternatives for farming animals.

Emergence, Dissemination and Antimicrobial Resistance of the Main Poultry-Associated Salmonella Serovars in Brazil

Salmonella infects poultry, and it is also a human foodborne pathogen. This bacterial genus is classified into several serovars/lineages, some of them showing high antimicrobial resistance (AMR). The ease of Salmonella transmission in farms, slaughterhouses, and eggs industries has made controlling it a real challenge in the poultry-production chains. This review describes the emergence, dissemination, and AMR of the main Salmonella serovars and lineages detected in Brazilian poultry. It is reported that few serovars emerged and have been more widely disseminated in breeders, broilers, and layers in the last 70 years. Salmonella Gallinarum was the first to spread on the farms, remaining as a concerning poultry pathogen. Salmonella Typhimurium and Enteritidis were also largely detected in poultry and foods (eggs, chicken, turkey), being associated with several human foodborne outbreaks. Salmonella Heidelberg and Minnesota have been more widely spread in recent years, resulting in frequent chicken/turkey meat contamination. A few more serovars (Infantis, Newport, Hadar, Senftenberg, Schwarzengrund, and Mbandaka, among others) were also detected, but less frequently and usually in specific poultry-production regions. AMR has been identified in most isolates, highlighting multi-drug resistance in specific poultry lineages from the serovars Typhimurium, Heidelberg, and Minnesota. Epidemiological studies are necessary to trace and control this pathogen in Brazilian commercial poultry production chains.

Dose-dependent effects of chronic lead toxicity in vivo: Focusing on trace elements and gut microbiota

Dose-dependent effects of chronic Pb exposure-induced injuries, especially on the trace elements and gut microbiota in mice, have not been explored. In the present study, we investigated these aspects using C57BL/6 mouse models that were exposed to Pb via drinking water with Pb concentrations of 0.1, 0.5, and 1.0 g/L for 8 weeks. The results showed that with the increase in chronic Pb exposure dose, the Pb levels in the blood and tissues, Zn levels in the kidney and brain were elevated, and the levels of bone Zn, kidney Fe, brain Mg, Ca, and Fe, renal catalase activity, and glutathione levels, as well as the expression of colonic zonula occludens-1 and occludin, decreased with a strong linear correlation. Moreover, the relative abundance of Marvinbryantia and Ruminococcus 1 increased, while that of Lactobacillus and Roseburia decreased linearly with the Pb exposure dose. PICRUSt analysis revealed that chronic Pb exposure had a greater impact on the metabolism of macronutrients, trace elements, and neurodegenerative injury. These findings suggest that chronic Pb exposure disrupts trace element levels in tissues, especially in the brain, and induces gut dysbiosis in a dose-dependent manner, which is different from the dose-effect of acute Pb toxicity.