Short-chain fatty acids andl-lactate as feed additives to controlCampylobacter jejuniinfections in broilers

Analyzing the morphology and avian β-defensins genes (AvβD) expression in the small intestine of Cobb500 broiler chicks fed with sodium butyrate

BACKGROUND

Sodium butyrate is a potential antibiotic growth promoter and has had advantageous effects on the poultry industry.

METHODS

Evaluating the effect of sodium butyrate on the intestinal villi and the humoral part of innate immunity of the male Cobb 500 broiler using scanning electron microscopy and quantitative real-time PCR analysis, the control group and treated group of Cobb 500 with SB supplemented received water containing 0.98 mg sodium butyrate.

RESULTS

The administration of sodium butyrate changed the villi characters, as the shape changed from tongue to long tongue. They were mainly parallel to each other and long finger-like at the duodenum. The tips of the villi in the control group appeared thin-slight curved with a prominent center in the duodenum, thin rectangular in the jejunum, and ileum in the control group. In contrast, in the treatment group, they changed to thick rectangular in the duodenum and ileum zigzag shape in the jejunum. The epithelium lining of the duodenal villi showed a dome shape, the jejunal villi showed a polygonal shape, and the ileal villi appeared scales-like. The epithelium lining showed irregular microfolds and many different-sized pores, and the treatment group showed islands of long microvilli in the duodenum and solitary long microvilli in the ileum. Real-time PCR of AvBD 1, 2, 10, and 12 significantly (P < 0.01). The better expression of AvBD 1, 2, and 12 was determined in the duodenum, while AvBD 10 was in the jejunum.

CONCLUSION

Sodium butyrate enhanced the chicks' growth and small intestine parameters, modified the morphology of the intestinal villi, and improved the humoral part of innate immunity.

Dual bacteriocin and extracellular vesicle-mediated inhibition of Campylobacter jejuni by the potential probiotic candidate Ligilactobacillus salivarius UO.C249

Campylobacter jejuni (C. jejuni) is one of the most common causes of foodborne infections worldwide and a major contributor to diarrheal diseases. This study aimed to explore the ability of commensal gut bacteria to control C. jejuni infection. Bacterial strains from the intestinal mucosa of broilers were screened in vitro against C. jejuni ATCC BAA1153. The cell-free supernatant (CFS) of Ligilactobacillus salivarius UO.C249 showed potent dose-dependent antimicrobial activity against the pathogen, likely due to the presence of bacteriocin-like moieties, as confirmed by protease treatment. Genome and exoproteome analyses revealed the presence of known bacteriocins, including Abp118. The genome of Lg. salivarius UO.C249 harbors a 1.8-Mb chromosome and a 203-kb megaplasmid. The strain was susceptible to several antibiotics and had a high survival rate in the simulated chicken gastrointestinal tract (GIT). Post-protease treatment revealed residual inhibitory activity, suggesting alternative antimicrobial mechanisms. Short-chain fatty acid (SCFA) quantification confirmed non-inhibitory levels of acetic (24.4 ± 1.2 mM), isovaleric (34 ± 1.0 µM), and butyric (32 ± 2.5 µM) acids. Interestingly, extracellular vesicles (EVs) isolated from the CFS of Lg. salivarius UO.C249 were found to inhibit C. jejuni ATCC BAA-1153. Proteome profiling of these EVs revealed the presence of unique proteins distinct from bacteriocins identified in CFS. The majority of the identified proteins in EVs are located in the membrane and play roles in transmembrane transport and peptidoglycan degradation, peptidase, proteolysis, and hydrolysis. These findings suggest that although bacteriocins are a primary antimicrobial mechanism, EV production also contributes to the inhibitory activity of Lg. salivarius UO.C249 against C. jejuni.

IMPORTANCE

Campylobacter jejuni (C. jejuni) is a major cause of gastroenteritis and a global public health concern. The increasing antibiotic resistance and lack of effective alternatives in livestock production pose serious challenges for controlling C. jejuni infections. Therefore, alternative strategies are needed to control this pathogen, especially in the poultry industry where it is prevalent and can be transmitted to humans through contaminated food products. In this study, Ligilactobacillus salivarius UO.C249 isolated from broiler intestinal mucosa inhibited C. jejuni and exhibited important probiotic features. Beyond bacteriocins, Lg. salivarius UO.C249 secretes antimicrobial extracellular vesicles (EVs) with a unique protein set distinct from bacteriocins that are involved in transmembrane transport and peptidoglycan degradation. Our findings suggest that beyond bacteriocins, EV production is also a distinct inhibitory signaling mechanism used by Lg. salivarius UO.C249 to control C. jejuni. These findings hold promise for the application of probiotic EVs for pathogen control.

Campylobacteriosis and Control Strategies against Campylobacters in Poultry Farms

Campylobacteriosis is a significant foodborne illness caused by Campylobacter bacteria. It is one of the most common bacterial causes of gastroenteritis worldwide, with poultry being a major reservoir and source of infection in humans. In poultry farms, Campylobacters colonize the intestinal tract of chickens and contaminate meat during processing. Vaccines under development against Campylobacters in poultry showed partial or no protection against their cecal colonization. Therefore, this review will elaborate on campylobacteriosis and emphasize the control strategies and recent vaccine trials against Campylobacters in poultry farms. The epidemiology, diagnosis, and treatment of Campylobacter infection, along with specific mention of poultry Campylobacter contamination events in Malaysia, will also be discussed.

Investigating bacteriophages as a novel multiple-hurdle measure against Campylobacter: field trials in commercial broiler plants

Campylobacter mitigation along the food production chain is considered effective for minimizing the public health burden of human campylobacteriosis. This study is the first combining different measures in a multiple-hurdle approach, using drinking water additives and feed additives in single and combined application schemes in commercial broiler plants. Broiler chickens in the study groups were naturally contaminated with Campylobacter. Application of an organic acid blend via drinking water, consisting of sodium propionate, potassium sorbate, and sodium diacetate, resulted in significant reductions of up to 4.9 log10 CFU/mL in fecal samples and in cecal samples at slaughter. The application of a phage mixture, consisting of Fletchervirus phage NCTC 12673 and Firehammervirus phage vB_CcM-LmqsCPL1/1, resulted in reductions of up to 1.1 log10 CFU/mL in fecal samples 1 day after dosing. The sole administration of curcumin via feed resulted in small and inconsistent reductions. In the group receiving a combination of all tested measures, reductions of up to 1.1 log10 CFU/mL were observed. Based on the results of our field trials, it was shown that both the sole application and the combined application of mitigation measures in primary production can reduce the Campylobacter load in broiler chickens, while no synergism could be observed.

Metabolomic signatures of intestinal colonization resistance against Campylobacter jejuni in mice

Introduction

Campylobacter jejuni stands out as one of the leading causes of bacterial enteritis. In contrast to humans, specific pathogen-free (SPF) laboratory mice display strict intestinal colonization resistance (CR) against C. jejuni, orchestrated by the specific murine intestinal microbiota, as shown by fecal microbiota transplantation (FMT) earlier.

Methods

Murine infection models, comprising SPF, SAB, hma, and mma mice were employed. FMT and microbiota depletion were confirmed by culture and culture-independent analyses. Targeted metabolome analyses of fecal samples provided insights into the associated metabolomic signatures.

Results

In comparison to hma mice, the murine intestinal microbiota of mma and SPF mice (with CR against C. jejuni) contained significantly elevated numbers of lactobacilli, and Mouse Intestinal Bacteroides, whereas numbers of enterobacteria, enterococci, and Clostridium coccoides group were reduced. Targeted metabolome analysis revealed that fecal samples from mice with CR contained increased levels of secondary bile acids and fatty acids with known antimicrobial activities, but reduced concentrations of amino acids essential for C. jejuni growth as compared to control animals without CR.

Discussion

The findings highlight the role of microbiota-mediated nutrient competition and antibacterial activities of intestinal metabolites in driving murine CR against C. jejuni. The study underscores the complex dynamics of host-microbiota-pathogen interactions and sets the stage for further investigations into the mechanisms driving CR against enteric infections.

Butyrate decreases Campylobacter jejuni motility and biofilm partially through influence on LysR expression

The food pathogen Campylobacter jejuni both colonizes the lower intestines of poultry and infects the lower intestines of humans. The lower intestines of both poultry and humans are also home to a wide range of commensal organisms which compete with an organism like C. jejuni for space and resources. The commensal organisms are believed to protect humans against infection by pathogens of the digestive tract like C. jejuni. The short chain fatty acid (SCFA) butyrate is a metabolite commonly produced by commensal organisms within both the poultry and human digestive tract. We investigated the effect that physiologically relevant concentrations of butyrate have on C. jejuni under in vitro conditions. Butyrate at concentrations of 5 and 20 mM negatively impacted C. jejuni motility and biofilm formation. These two traits are believed important for C. jejuni's ability to infect the lower intestines of humans. Additionally, 20 mM butyrate concentrations were observed to influence the expression of a range of different Campylobacter proteins. Constitutive expression of one of these proteins, LysR, within a C. jejuni strain partially lessened the negative influence butyrate had on the bacteria's motility.

The Modulatory Effect of Sodium Propionate Treatment in the Expression of Inflammatory Cytokines and Intracellular Growth of Brucella abortus 544 in Raw 264.7 Cells

In this study, we investigated the effects of sodium propionate (SP) treatment on intracellular mechanism of murine macrophages and its contribution to host immunity during Brucella abortus 544 infection. The intracellular growth assay revealed that SP inhibited Brucella replication inside the macrophages. To determine intracellular signaling involved during SP treatment after Brucella infection, we analyzed the change of five different cytokines production relevant to SP such as TNF-α, IL-10, IFN-γ, IL-1β, and IL-6, and the results indicated that the boost with IL-10 was apparent throughout the culture period for 48 h as well as IL-1β which was apparent at 24 h post-infection and IFN-γ which was apparent at 24 h and 48 h in comparison to SP untreated groups. On the other way, SP-treated cells displayed suppressed production of TNF-α and IL-6 at all time points tested and 48 h post-infection, respectively. Furthermore, we conducted western blot to establish a cellular mechanism, and the result suggested that SP treatment attenuated p50 phosphorylation, part of the NF-κB pathway. These findings indicated that the inhibitory effect of SP against Brucella infection could be attributed through induction of cytokine production and interference on intracellular pathway, suggesting SP as a potential candidate for treating brucellosis.

Effects of Short- and Medium-Chain Fatty Acids on Production, Meat Quality, and Microbial Attributes-A Review

The non-therapeutic use of antimicrobials in poultry production contributes to the spread of drug-resistant pathogens in both birds and humans. Antibiotics are known to enhance feed efficiency and promote the growth and weight gain of poultry. New regulatory requirements and consumer preferences have led to a reduced use of antibiotics in poultry production and to the discovery of natural alternatives to antibiotic growth promoters. This interest is not only focused on the direct removal or inhibition of causative microorganisms but also on the prevention of diseases caused by enteric pathogens using a range of feed additives. A group of promising feed additives is composed of short- and medium-chain fatty acids (SCFAs and MCFAs) and their derivatives. MCFAs possess antibacterial, anticoccidial, and antiviral effects. In addition, it has been proven that these acids act in synergy if they are used together with organic acids, essential oils, or probiotics. These fatty acids also benefit intestinal health integrity and homeostasis in broilers. Other effects have been documented as well, such as an increase in intestinal angiogenesis and the gene expression of tight junctions. The aim of this review is to provide an overview of SCFAs and MCFAs as alternatives to antibiotic growth promoters and to summarize the current findings in the literature to show their possible benefits on production, meat quality, and gut health in poultry.

Butyrate as a Potential Driver of a Dysbiotic Shift of the Tongue Microbiota

The tongue dorsum is colonized by a stable microbiota, mostly comprising common commensal taxa. However, the predominance of each taxon varies among individuals. We hypothesized that equilibrium in the tongue microbiota is affected by exposure to butyrate in the oral fluid, which is reported to affect the growth of specific microorganisms. In this study, the bacterial composition of the tongue microbiotas of 69 male adults was determined via 16S rRNA gene sequencing to investigate its relationship to n-butyric acid concentration in oral rinse samples. The tongue microbiotas of individuals with a higher n-butyric acid level had higher relative abundances of Prevotella histicola, Veillonella atypica, and Streptococcus parasanguinis and lower relative abundances of Neisseria subflava and Porphyromonas pasteri. Subsequently, tongue microbiota samples collected from 12 adults were cultivated for 13 h in basal medium containing mucin and different concentrations of sodium butyrate (0, 0.8, 1.6, and 3.2 mM) to assess its effect on the growth of tongue microbiota organisms. The bacterial composition of the cultivated tongue microbiotas also demonstrated a significant gradual shift with an increase in sodium butyrate levels in beta-diversity analysis. N. subflava was significantly less predominant in the microbiota after cultivation with an increased addition of sodium butyrate, although no statistical difference was observed in the other aforementioned taxa. These results suggest that butyrate in the oral fluid is partially involved in the dysbiotic shift of the tongue microbiota. IMPORTANCE Oral microbial populations that are always ingested with saliva have attracted increasing attention because more oral microorganisms than previously known reach distal organs, such as the lungs and intestinal tract, thereby affecting our health. However, although such organisms are predominately derived from the tongue dorsum, the dynamics and determinants of the tongue microbiota composition remain unclear. This study demonstrated that exposure to butyrate could lead to a dysbiotic shift in the tongue microbiota using an observational epidemiological and microbiota cultivation approach. This result adds a new dimension to tongue microbiota ecology.

Recombinant production of a diffusible signal factor inhibits Salmonella invasion and animal carriage

The complex chemical environment of the intestine is defined largely by the metabolic products of the resident microbiota. Enteric pathogens, elegantly evolved to thrive in the gut, use these chemical products as signals to recognize specific niches and to promote their survival and virulence. Our previous work has shown that a specific class of quorum-sensing molecules found within the gut, termed diffusible signal factors (DSF), signals the repression of Salmonella tissue invasion, thus defining a means by which this pathogen recognizes its location and modulates virulence to optimize its survival. Here, we determined whether the recombinant production of a DSF could reduce Salmonella virulence in vitro and in vivo. We found that the most potent repressor of Salmonella invasion, cis-2-hexadecenoic acid (c2-HDA), could be recombinantly produced in E. coli by the addition of a single exogenous gene encoding a fatty acid enoyl-CoA dehydratase/thioesterase and that co-culture of the recombinant strain with Salmonella potently inhibited tissue invasion by repressing Salmonella genes required for this essential virulence function. Using the well characterized E. coli Nissle 1917 strain and a chicken infection model, we found that the recombinant DSF-producing strain could be stably maintained in the large intestine. Further, challenge studies demonstrated that this recombinant organism could significantly reduce Salmonella colonization of the cecum, the site of carriage in this animal species. These findings thus describe a plausible means by which Salmonella virulence may be affected in animals by in situ chemical manipulation of functions essential for colonization and virulence.

Antimicrobial effect of a drinking water additive comprising four organic acids on Campylobacter load in broilers and monitoring of bacterial susceptibility

Application of organic acids via feed or drinking water is under discussion as a possible intervention strategy to reduce Campylobacter (C.) load in primary poultry production. A previous in vitro study showed that reduced concentrations of sorbic acid, benzoic acid, propionic acid, and acetic acid were required for antibacterial activity against Campylobacter when using a mixture of these 4 acids compared to when using the single acids. The present study aimed at determining the antibacterial efficiency of this combination in vivo as a drinking water additive for reducing shedding and intestinal C. jejuni colonization in broilers. Furthermore, we assessed whether the inoculated C. jejuni strain BfR-CA-14430 adapted in vivo to the applied organic acids. Results of this study showed that adding the organic acids consistently reduced Campylobacter loads in cloacal swabs. While significant reductions were observed within the entire study period, a maximum 2 log reduction occurred at an age of 18 d. However, after dissection at the end of the trial, no significant differences were detected in Campylobacter loads of cecal and colon contents compared to the control group. Susceptibility testing of re-isolates from cloacal swabs and cecal content revealed equal minimum inhibitory concentration (MIC) values compared to the inoculated test strain, suggesting that C. jejuni remained susceptible throughout the trial.

Campylobacter jejuni in Poultry: Pathogenesis and Control Strategies

C. jejuni is the leading cause of human foodborne illness associated with poultry, beef, and pork consumption. C. jejuni is highly prevalent in commercial poultry farms, where horizontal transmission from the environment is considered to be the primary source of C. jejuni. As an enteric pathogen, C. jejuni expresses virulence factors regulated by a two-component system that mediates C. jejuni's ability to survive in the host. C. jejuni survives and reproduces in the avian intestinal mucus. The avian intestinal mucus is highly sulfated and sialylated compared with the human mucus modulating C. jejuni pathogenicity into a near commensal bacteria in poultry. Birds are usually infected from two to four weeks of age and remain colonized until they reach market age. A small dose of C. jejuni (around 35 CFU/mL) is sufficient for successful bird colonization. In the U.S., where chickens are raised under antibiotic-free environments, additional strategies are required to reduce C. jejuni prevalence on broilers farms. Strict biosecurity measures can decrease C. jejuni prevalence by more than 50% in broilers at market age. Vaccination and probiotics, prebiotics, synbiotics, organic acids, bacteriophages, bacteriocins, and quorum sensing inhibitors supplementation can improve gut health and competitively exclude C. jejuni load in broilers. Most of the mentioned strategies showed promising results; however, they are not fully implemented in poultry production. Current knowledge on C. jejuni's morphology, source of transmission, pathogenesis in poultry, and available preharvest strategies to decrease C. jejuni colonization in broilers are addressed in this review.

Systematic review of products with potential application for use in the control of Campylobacter spp. in organic and free-range broilers

Campylobacter spp. are some of the most important food-borne zoonoses in Europe and broiler meat is considered the main source of Campylobacter infections. Organic and free-range broilers have access to outdoor reservoirs of Campylobacter and are more frequently infected at slaughter than the conventional broiler flocks. Limitations to biosecurity and treatment options in these production types calls for additional solutions. This review examines intervention methods with sufficient strength and quality, which are able to reduce the load of Campylobacter safely and efficiently and discuss their applicability in organic and free-range broiler production. Four different products passed the inclusion criteria and their quality examined: ferric tyrosine chelate, a prebiotic fermentation product of Saccharomyces cerevisiae, short-chain fatty acid butyrate coated on microbeads added to feed, and a mix of organic acids added to the drinking water. Though potential candidates for reducing Campylobacter in broilers were identified, there is a lack of large scale intervention studies that demonstrate an effect under field conditions of a free-range broiler production.

The Use of Disinfectant in Barn Cleaning Alters Microbial Composition and Increases Carriage of Campylobacter jejuni in Broiler Chickens

To maintain food safety and flock health in broiler chicken production, biosecurity approaches to keep chicken barns free of pathogens are important. Canadian broiler chicken producers must deep clean their barns with chemical disinfectants at least once annually (full disinfection [FD]) and may wash with water (water wash [WW]) throughout the year. However, many producers use FD after each flock, assuming a greater efficacy of more stringent cleaning protocols, although little information is known regarding how these two cleaning practices affect pathogen population and gut microbiota. In the present study, a crossover experiment over four production cycles was conducted in seven commercial chicken barns to compare WW and FD. We evaluated the effects of barn cleaning methods on commercial broiler performance, cecal microbiota composition, Campylobacter and Salmonella occurrence, and Campylobacter jejuni and Clostridium perfringens abundance, as well as on short-chain fatty acid (SCFA) concentrations in the month-old broiler gut. The 30-day body weight and mortality rate were not affected by the barn cleaning methods. The WW resulted in a modest but significant effect on the structure of broiler cecal microbiota (weighted-UniFrac; adonis P = 0.05, and unweighted-UniFrac; adonis P = 0.01), with notable reductions in C. jejuni occurrence and abundance. In addition, the WW group had increased cecal acetate, butyrate, and total SCFA concentrations, which were negatively correlated with C. jejuni abundance. Our results suggest that WW may result in enhanced activity of the gut microbiota and reduced zoonotic transmission of C. jejuni in broiler production relative to FD in the absence of a disease challenge. IMPORTANCE We compared the effects of barn FD and WW methods on gut microbial community structures and pathogen prevalence of broiler chickens in a nonchallenging commercial production setting. The results revealed that barn cleaning methods had little impact on the 30-day body weight and mortality rate of broiler chickens. In addition, the FD treatment had a subtle but significant effect on the broiler cecal microbiota with increased abundances of Campylobacter and decreased SCFA concentrations, which would support the adoption of WW as a standard practice. Thus, compared to FD, WW can be beneficial to broiler chicken production by inhibiting zoonotic pathogen colonization in the chicken gut with reduced cost and labor of cleaning.

Effects of Common Litter Management Practices on the Prevalence of Campylobacter jejuni in Broilers

Simple Summary

The bacterium Campylobacter is a significant cause of foodborne illness, causing over one million cases per year in the United States. Campylobacter is naturally found in chickens and can contaminate chicken products; therefore, strategies to lower Campylobacter presence in chickens are important to public health. Commercial chickens are raised in houses with bedding material, or litter, covering the floor. Litter can become contaminated with Campylobacter, which in turn will then colonize the birds. In some countries, after a flock of chickens is harvested, the litter is treated and reused for the next flock, which could spread Campylobacter. The goal of this study was to observe if reusing contaminated litter could indeed spread Campylobacter and to determine if common litter treatments were able to prevent contamination of the next flock. To determine this, previously used litter contaminated with Campylobacter was composted and treated with sodium bisulfate. A flock was raised on this litter and tested for Campylobacter for 42 days. No Campylobacter was detected in any of these samples, indicating that re-used litter is not a probable source for Campylobacter contamination of chickens.

Abstract

Campylobacter is an important foodborne pathogen and is naturally found in chickens. During broiler production, litter can become contaminated with Campylobacter when birds defecate, and this litter, in some countries, is typically reused for the next flock, potentially causing cross-contamination. The goal of this experiment was to observe if reusing contaminated litter could spread Campylobacter between flocks and to observe if common litter treatments could prevent this cross-contamination. To determine this, a flock of birds was inoculated with Campylobacter jejuni and allowed to naturally contaminate the litter for 42 days. After grow-out, birds were terminated, and litter was given five treatments: uninoculated fresh litter, untreated re-used litter, composted re-used litter, re-used litter treated with sodium bisulfate (45 kg/305 m²), and re-used litter composted and treated with sodium bisulfate (45 kg/305 m²). A second flock was placed on the litter, grown for 42 days, and tested for C. jejuni prevalence. Following inoculation of the first flock, high prevalence of C. jejuni was observed; however, after a 19-day down-time between flocks, no C. jejuni was detected in any samples from the second flock. These results indicate that re-used litter was not a significant reservoir for cross-contamination of broilers when provided a significant down-time between flocks.

Dual role of microbiota-derived short-chain fatty acids on host and pathogen

A growing body of documents shows microbiota produce metabolites such as short-chain fatty acids (SCFAs) as crucial executors of diet-based microbial influence the host and bacterial pathogens. The production of SCFAs depends on the metabolic activity of intestinal microflora and is also affected by dietary changes. SCFAs play important roles in maintaining colonic health as an energy source, as a regulator of gene expression and cell differentiation, and as an anti-inflammatory agent. Additionally, the regulated expression of virulence genes is critical for successful infection by an intestinal pathogen. Bacteria rely on sensing environmental signals to find preferable niches and reach the infectious state. This review will present data supporting the diverse functional roles of microbiota-derived butyrate, propionate, and acetate on host cellular activities such as immune modulation, energy metabolism, nervous system, inflammation, cellular differentiation, and anti-tumor effects, among others. On the other hand, we will discuss and summarize data about the role of these SCFAs on the virulence factor of bacterial pathogens. In this regard, receptors and signaling routes for SCFAs metabolites in host and pathogens will be introduced.

Effects of a mixture of mono-glycerides of butyric-, capric-, and caprylic acid with chlortetracycline on the growth performance, intestine morphology, and cecal microflora of broiler birds

This study aimed to investigate the effects of a mixture of mono-glycerides of butyric-, capric-, and caprylic acid (MMG) on the growth performance, intestinal morphology, and cecal microflora of broilers. A total of 960 male Arbor Acre broilers were offered basal diets with or without Chlortetracycline additive (CA) at 500 g/t, and MMG at 3,000, 1,000, or 650 g/t, with 8 replicates of 20 birds per treatment. The results confirmed 500 g/t CA with/without 1,000 g/t MMG increased the average daily weight gain (ADG) of birds compared to the control group 1 during the 42-d experimental period (P < 0.05). Comparing to the control group 1, 500 g/t CA with either 650 g or 1,000 g/t MMG or 1,000 g MMG alone increased the ADG of birds during the late growth stage (22–42 d) (P < 0.05). On d 42, the serum triglyceride levels were higher (P < 0.05) in groups supplemented with CA and CA + 1,000 g/t MMG comparing to the control group; while urea nitrogen level was higher in the control group comparing to the rest of treatment groups Compared to the control group 1, 1,000 g/t MMG alone without CA decreased the abundance of Faecalibacterium and Bacteroides but increased the abundance of Escherichia/Shiegella. About 500 g/t CA alone treatment group had higher abundance of Lactobacillus comparing to the rest of groups. In conclusion, dietary supplement with MMG showed beneficial efficacy on the growth and intestinal function of broilers, demonstrating the potential value of MMG to poultry industry. In terms of dosage, the current trial shows that 3,000 g/t (1–21 d) and 1,000 g/t (22–42 d) MMG without CA was the appropriate dietary supplemented rate for broilers. And the mixed use of 500 g/t CA and 1,000 g/t MMG was benefit for broilers at 22 to 42 d.

Effects of Clostridium butyricum, Sodium Butyrate, and Butyric Acid Glycerides on the Reproductive Performance, Egg Quality, Intestinal Health, and Offspring Performance of Yellow-Feathered Breeder Hens

Butyrate has been reported to promote the performance and growth of chickens. The specific roles and efficacy of different sources of butyrate remained unclear. Thus, the present study aimed to investigate and compare the effects of Clostridium butyricum (CB), sodium butyrate (SB), and butyric acid glycerides (tributyrin, BAG) on the reproductive performance, egg quality, intestinal health, and offspring performance of yellow-feathered breeder hens. A total of 300 Lingnan yellow-feathered breeder hens were assigned to five treatment groups: control (CL), 1×10⁸CFU/kg CB (CBL), 1×10⁹CFU/kg CB (CBH), 500mg/kg SB, and 300mg/kg BAG. Results showed that the laying performance and egg quality were increased by CBL, CBH, and BAG. Both CB treatments increased the hatchability of fertilized eggs. Maternal supplementation with both levels of CB significantly elevated the growth performance of offspring. Treatment with CBL, CBH, SB, and BAG all improved the oviduct-related variables and reduced the plasmal antioxidant variables. The CBH, CBL, and BAG treatments also improved the intestinal morphology to different degrees. Jejunal contents of IL-6 were decreased by CBH and BAG, while those of IL-4, IL-6, IL-1β, and IgY were decreased by SB. Transcripts of nutrient transporters in jejunal mucosa were also upregulated by CBH, CBL, and SB treatments and expression of Bcl-2-associated X protein was decreased by CBL, CBH, and BAG. In cecal contents, CBL increased the abundance of Firmicutes and Bacillus, while CBH decreased the abundance of Proteobacteria. Also, the co-occurrence networks of intestinal microbes were regulated by CBH and BAG. In conclusion, dietary inclusion of CB and BAG improved the reproductive parameters, egg quality, and intestinal morphology of breeders. CB also influenced the hatching performance of breeders and growth performance of the offspring, while SB improved the oviduct-related variables. These beneficial effects may result from the regulation of cytokines, nutrient transporters, apoptosis, and gut microbiota; high-level CB had more obvious impact. Further study is needed to explore and understand the correlation between the altered gut microbiota induced by butyrate and the performance, egg quality, intestinal health, and also offspring performance.

Short-Chain Fatty Acids as a Potential Treatment for Infections: a Closer Look at the Lungs

Short-chain fatty acids (SCFAs) are the main metabolites produced by the gut microbiota via the fermentation of complex carbohydrates and fibers. Evidence suggests that SCFAs play a role in the control of infections through direct action both on microorganisms and on host signaling. This review summarizes the main microbicidal effects of SCFAs and discusses studies highlighting the effect of SCFAs in the virulence and viability of microorganisms. We also describe the diverse and complex modes of action of the SCFAs on the immune system in the face of infections with a specific focus on bacterial and viral respiratory infections. A growing body of evidence suggests that SCFAs protect against lung infections. Finally, we present potential strategies that may be leveraged to exploit the biological properties of SCFAs for increasing effectiveness and optimizing patient benefits.

The efficacy of organic acid, medium chain fatty acid and essential oil based broiler treatments; in vitro anti-Campylobacter jejuni activity and the effect of these chemical-based treatments on broiler performance

AIMS

This research tested the anti-Campylobacter properties of organic acids (OA), medium chain fatty acids (MCFA) and essential oils (EO) in vitro and commenced in vivo suitability testing focused on broiler performance.

METHODS AND RESULTS

Nine active compounds were tested at different concentrations and times against Campylobacter jejuni in sterile distilled water, Mueller Hinton broth and grower feed digestate (GFD). Sodium caprate (1.5%, v/v), thymol (0.25% and 2.5%, v/v), carvacrol (1.25%, v/v) and potassium sorbate (1.5%, v/v) each achieved C. jejuni reductions of ≥4.5 log₁₀  CFU per ml in GFD, the matrix most representative of the broiler gut, after 60 s. Similar reductions were achieved after 60 min with lactic acid (1.25%, v/v), formic acid (3.1%, v/v), sodium caprylate (1.5%, v/v) and carvacrol (1.25%, v/v). However, in vivo these compounds adversely affected broiler performance, resulting in dimished water intake and reduced weight.

CONCLUSIONS

OA, MFCA and EO based compounds are effective anti-Campylobacter treatments in laboratory model studies but cannot be applied in vivo.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study illustrates that OAs, MCFAs and EOs can achieve significant reductions in Campylobacter in vitro but identifies a major issue, inhibition of broiler performance, preventing their use in practice.

Long-Term Grow-Out Affects Campylobacter jejuni Colonization Fitness in Coincidence With Altered Microbiota and Lipid Composition in the Cecum of Laying Hens

Campylobacter jejuni is one of the leading causes of gastrointestinal illness worldwide and is mainly transmitted from chicken through the food chain. Previous studies have provided increasing evidence that this pathogen can colonize and replicate in broiler chicken during its breeding; however, its temporal kinetics in laying hen are poorly understood. Considering the possible interaction between C. jejuni and gut microbiota, the current study was conducted to address the temporal dynamics of C. jejuni in the cecum of laying hen over 40 weeks, with possible alteration of the gut microbiota and fatty acid (FA) components. Following oral infection with C. jejuni 81-176, inocula were stably recovered from ceca for up to 8 weeks post-infection (p.i.). From 16 weeks p.i., most birds became negative for C. jejuni and remained negative up to 40 weeks p.i. 16S rRNA gene sequencing analyses revealed that most of the altered relative rRNA gene abundances occurred in the order Clostridiales, in which increased relative rRNA gene abundances were observed at >16 weeks p.i. in the families Clostridiaceae, Ruminococcaceae, Lachnospiraceae, and Peptococcaceae. Lipidome analyses revealed increased levels of sterols associated with bile acid metabolisms in the cecum at 16 and/or 24 weeks p.i. compared with those detected at 8 weeks p.i., suggesting that altered microbiota and bile acid metabolism might underlie the decreased colonization fitness of C. jejuni in the gut of laying hens.

On farm interventions to minimise Campylobacter spp. contamination in chicken

1. This review explores current and proposed on-farm interventions and assess the potential of these interventions against Campylobacter spp. 2. Interventions such as vaccination, feed/water-additives and, most importantly, consistent biosecurity, exhibit potential for the effective control of this pathogen and its dissemination within the food chain. 3. Due to the extensive diversity in the Campylobacter spp. genome and surface-expressed proteins, vaccination of poultry is not yet regarded as a completely effective strategy. 4. The acidification of drinking water through the addition of organic acids has been reported to decrease the risk of Campylobacter spp. colonisation in broiler flocks. Whilst this treatment alone will not completely protect birds, use of water acidification in combination with in-feed measures to further reduce the level of Campylobacter spp. colonisation in poultry may be an option meriting further exploration. 5. The use of varied types of feed supplements to reduce the intestinal population and shedding rate of Campylobacter spp. in poultry is an area of growing interest in the poultry industry. Such supplements include pro - and pre-biotics, organic acids, bacteriocins and bacteriophage, which may be added to feed and water. 6. From the literature, it is clear that a distinct, albeit not unexpected, difference between the performance of in-feed interventions exists when examined in vitro compared to those determined in in vivo studies. It is much more likely that pooling some of the discussed approaches in the in-feed tool kit will provide an answer. 7. Whilst on-farm biosecurity is essential to maintain a healthy flock and reduce disease transmission, even the most stringent biosecurity measures may not have sufficient, consistent and predictable effects in controlling Campylobacter spp. Furthermore, the combination of varied dietary approaches and improved biosecurity measures may synergistically improve control.

New and alternative strategies for the prevention, control, and treatment of antibiotic-resistant Campylobacter

Campylobacter is an enteric pathogen and a leading bacterial cause of diarrhea worldwide. It is widely distributed in food animal species and is transmitted to humans primarily through the foodborne route. While generally causing self-limited diarrhea in humans, Campylobacter may induce severe or systemic infections in immunocompromised or young/elderly patients, which often requires antibiotic therapy with the first-line antibiotics including fluoroquinolones and macrolides. Over the past decades, Campylobacter has acquired resistance to these clinically significant antibiotics, compromising the effectiveness of antibiotic treatments. To address this concern, many studies have been conducted to advance novel and alternative measures to control antibiotic-resistant Campylobacter in animal reservoirs and in the human host. Although some of these undertakings have yielded promising results, efficacious and reliable alternative approaches are yet to be developed. In this review article, we will describe Campylobacter-associated disease spectrums and current treatment options, discuss the state of antibiotic resistance and alternative therapies, and provide an evaluation of various approaches that are being developed to control Campylobacter infections in animal reservoirs and the human host.

In vivo efficacy of carvacrol on Campylobacter jejuni prevalence in broiler chickens during an entire fattening period

Carvacrol, a primary constituent of plant essential oils (EOs), and its antimicrobial activity have been the subject of many in vitro studies. Due to an increasing demand for alternative antimicrobials and an emerging number of antibiotic resistant bacteria, the use of essential oils has played a major role in many recent approaches to reduce Campylobacter colonization in poultry before slaughter age. For that purpose, the reducing effect of carvacrol on Campylobacter jejuni prevalence in broilers was determined in vivo in an experimental broiler chicken model during an entire fattening period. Carvacrol was added to the feed in a concentration of 120 mg/kg feed four days post hatch until the end of the trial. In this study, we demonstrated a statistically significant decrease of C. jejuni counts by 1.17 decadic logarithm (log10) most probable number (MPN)/g in cloacal swabs during starter and grower periods (corresponding to a broilers age between 1 and 28 days). Similar results were observed for colon enumeration at the end of the trial where C. jejuni counts were significantly reduced by 1.25 log10 MPN/g. However, carvacrol did not successfully reduce Campylobacter cecal colonization in 33-day-old broilers.

A three-dimensional intestinal tissue model reveals factors and small regulatory RNAs important for colonization with Campylobacter jejuni

The Gram-negative Epsilonproteobacterium Campylobacter jejuni is currently the most prevalent bacterial foodborne pathogen. Like for many other human pathogens, infection studies with C. jejuni mainly employ artificial animal or cell culture models that can be limited in their ability to reflect the in-vivo environment within the human host. Here, we report the development and application of a human three-dimensional (3D) infection model based on tissue engineering to study host-pathogen interactions. Our intestinal 3D tissue model is built on a decellularized extracellular matrix scaffold, which is reseeded with human Caco-2 cells. Dynamic culture conditions enable the formation of a polarized mucosal epithelial barrier reminiscent of the 3D microarchitecture of the human small intestine. Infection with C. jejuni demonstrates that the 3D tissue model can reveal isolate-dependent colonization and barrier disruption phenotypes accompanied by perturbed localization of cell-cell junctions. Pathogenesis-related phenotypes of C. jejuni mutant strains in the 3D model deviated from those obtained with 2D-monolayers, but recapitulated phenotypes previously observed in animal models. Moreover, we demonstrate the involvement of a small regulatory RNA pair, CJnc180/190, during infections and observe different phenotypes of CJnc180/190 mutant strains in 2D vs. 3D infection models. Hereby, the CJnc190 sRNA exerts its pathogenic influence, at least in part, via repression of PtmG, which is involved in flagellin modification. Our results suggest that the Caco-2 cell-based 3D tissue model is a valuable and biologically relevant tool between in-vitro and in-vivo infection models to study virulence of C. jejuni and other gastrointestinal pathogens.

Enteric pathogens have evolved numerous strategies to successfully colonize and persist in the human gastrointestinal tract. However, especially for the research of virulence mechanisms of human pathogens, often only limited infection models are available. Here, we have applied and further advanced a tissue-engineered human intestinal tissue model based on an extracellular matrix scaffold reseeded with human cells that can faithfully mimic pathogenesis-determining processes of the zoonotic pathogen Campylobacter jejuni. Our three-dimensional (3D) intestinal infection model allows for the assessment of epithelial barrier function during infection as well as for the quantification of bacterial adherence, internalization, and transmigration. Investigation of C. jejuni mutant strains in our 3D tissue model revealed isolate-specific infection phenotypes, in-vivo relevant infection outcomes, and uncovered the involvement of a small RNA pair during C. jejuni pathogenesis. Overall, our results demonstrate the power of tissue-engineered models for studying host-pathogen interactions, and our model will also be helpful to investigate other gastrointestinal pathogens.

Caecal Microbiota of Experimentally Campylobacter jejuni-Infected Chickens at Different Ages

Campylobacter jejuni is the most common bacterial cause of foodborne zoonosis in the European Union. Infections are often linked to the consumption and handling of poultry meat. The aim of the present study was to investigate the caecal microbiota of birds infected with C. jejuni at different ages. Therefore, a total of 180 birds of the laying hybrid Lohmann Brown-Classic were housed in 12 subgroups of 15 animals each in three performed repetitions. Three birds per subgroup were experimentally infected with C. jejuni at an age of about 21 days and about 78 days (4.46 ± 0.35 log10 CFU/bird). Twenty-one days after experimental infection, microbiome studies were performed on 72 caecal samples of dissected birds (three primary infected and three further birds/subgroup). Amplification within the hypervariable region V 4 of the 16S rRNA gene was performed and sequenced with the Illumina MiSeq platform. Statistical analyses were performed using SAS® Enterprise Guide® (version 7.1) and R (version 3.5.2). Both factors, the experimental replication (p < 0.001) and the chickens' age at infection (p < 0.001) contributed significantly to the differences in microbial composition of the caecal samples. The factor experimental replication explained 24% of the sample's variability, whereas the factor age at infection explained 14% thereof. Twelve of 32 families showed a significantly different count profile between the two age groups, whereby strongest differences were seen for seven families, among them the family Campylobacteraceae (adjusted p = 0.003). The strongest difference between age groups was seen for a bacterial species that is assigned to the genus Turicibacter which in turn belongs to the family Erysipelotrichaceae (adjusted p < 0.0001). Correlation analyses revealed a common relationship in both chicken ages at infection between the absolute abundance of Campylobacteraceae and Alcaligenaceae, which consists of the genus Parasutterella. In general, concentrations of particular volatile fatty acids (VFA) demonstrated a negative correlation to absolute abundance of Campylobacteraceae, whereby the strongest link was seen for n-butyrate (-0.51141; p < 0.0001). Despite performing consecutive repetitions, the factor experimental replication contributed more to the differences of microbial composition in comparison to the factor age at infection.

Inhibition and Interactions of Campylobacter jejuni from Broiler Chicken Houses with Organic Acids

Campylobacter jejuni is a bacterium that causes major diarrheal disease worldwide and is also one of the top five foodborne pathogens encountered in the United States. Poultry is a major source of C. jejuni, and a high-risk factor for contracting campylobacteriosis. Organic acids are used in the United States during food animal processing for removal of bacterial contamination from animal carcasses. Six organic acids were evaluated in inhibition studies of 96 C. jejuni strains obtained from shoe covers used in broiler chicken houses at different poultry farms in several states by determining the susceptibilities of the C. jejuni strains, along with the pH values at the molar minimum inhibitory concentrations (MICMs). The undissociated and dissociated organic acid concentrations were calculated at the MICMs with the Henderson-Hasselbalch equation. The results for the 96 C. jejuni strains were treated similarly for each different organic acid. Campylobacter jejuni inhibition did correlate with the dissociated organic acids, but did not correlate with pH or with the undissociated organic acids. When the concentrations of dissociated organic acids decreased, the C. jejuni strains were not disinfected. A carcass wash using organic acids should have the concentration of dissociated acid species carefully controlled. It is suggested to maintain a dissociated acid concentration for propionic, l-lactic, formic, citric, butyric, and acetic acids at 24, 40, 36, 21, 23, and 25 mM, respectively, and at these dissociated organic acid levels an acid wash would be expected to remove or inhibit 97% or more of the C. jejuni bacteria studied here. However, studies must be undertaken to confirm that the suggested concentrations of dissociated organic acids are adequate to remove C. jejuni bacteria in the field vs. the laboratory. Due to propionate, l-lactate, formate, butyrate, and acetate being utilized by C. jejuni, these organic acids may not be appropriate for use as a carcass wash to remove C. jejuni surface contamination. Of all tested organic acids, dissociated citric acid was the most efficient at inhibiting C. jejuni.

Essential Oils as an Intervention Strategy to Reduce Campylobacter in Poultry Production: A Review

Campylobacter is a major foodborne pathogen and can be acquired through consumption of poultry products. With 1.3 million United States cases a year, the high prevalence of Campylobacter within the poultry gastrointestinal tract is a public health concern and thus a target for the development of intervention strategies. Increasing demand for antibiotic-free products has led to the promotion of various alternative pathogen control measures both at the farm and processing level. One such measure includes utilizing essential oils in both pre- and post-harvest settings. Essential oils are derived from plant-based extracts, and there are currently over 300 commercially available compounds. They have been proposed to control Campylobacter in the gastrointestinal tract of broilers. When used in concentrations low enough to not influence sensory characteristics, essential oils have also been proposed to decrease bacterial contamination of the poultry product during processing. This review explores the use of essential oils, particularly thymol, carvacrol, and cinnamaldehyde, and their role in reducing Campylobacter concentrations both pre- and post-harvest. This review also details the suggested mechanisms of action of essential oils on Campylobacter.

The role of whey on the performance and campylobacteriosis in broiler chicks

The objective of the present study was to investigate the effect of the whey on broiler chicks' performance, welfare, and caecal Campylobacter counts under experimental and field conditions. In the experimental study, 120-d-old broiler chicks were randomly allocated to four treatment groups, as described below: group A, which served as negative control; group B, fed with a diet supplemented with 1% whey; group C, challenged with Campylobacter jejuni; and group D, supplemented with 1% whey and challenged with C. jejuni, respectively. Performance indexes and caecal C. jejuni counts were calculated. In addition to the performance indexes, the hock burn and the foot pad dermatitis lesions score were measured to assess the welfare status of broiler chicks. In order to evaluate the use of whey under field conditions, a second study was performed in a broiler farm with two identical houses. The evaluation of the experimental data revealed that the use of whey did not affect significantly the performance (P ≤ 0.05) and the caecal C. jejuni counts (P ≤ 0.05). There were neither footpad dermatitis lesions nor hock burn lesions in any of the experimental groups. In the field study, the use of whey had no effect on the performance indexes (P ≤ 0.05). It can be concluded that the addition of whey has no negative effect on poultry and may provide an alternative natural feed additive for the broiler feed industry.

Impact of Eimeria tenella Coinfection on Campylobacter jejuni Colonization of the Chicken

Eimeria tenella can cause the disease coccidiosis in chickens. The direct and often detrimental impact of this parasite on chicken health, welfare, and productivity is well recognized; however, less is known about the secondary effects that infection may have on other gut pathogens. Campylobacter jejuni is the leading cause of human bacterial foodborne disease in many countries and has been demonstrated to exert negative effects on poultry welfare and production in some broiler lines. Previous studies have shown that concurrent Eimeria infection can influence the colonization and replication of bacteria, such as Clostridium perfringens and Salmonella enterica serovar Typhimurium. Through a series of in vivo coinfection experiments, this study evaluated the impact that E. tenella infection had on C. jejuni colonization of chickens, including the influence of variations in parasite dose and sampling time after bacterial challenge. Coinfection with E. tenella resulted in a significant increase in C. jejuni colonization in the cecum in a parasite dose-dependent manner but a significant decrease in C. jejuni colonization in the spleen and liver of chickens. The results were reproducible at 3 and 10 days after bacterial infection. This work highlights that E. tenella not only has a direct impact on the health and well-being of chickens but can have secondary effects on important zoonotic pathogens.

Influence of lauric acid on the susceptibility of chickens to an experimental Campylobacter jejuni colonisation

Among the organic acids, lauric acid has shown a high level of in vitro activity against Campylobacter jejuni. The prevalence and intensity of C. jejuni excretion at slaughter often becomes lower with increasing age. In higher-aged broilers on organic farms which often use other breeds, in turn, the prevalence of C. jejuni is sometimes higher at slaughter. The question then arises as to whether a diet with higher lauric acid concentrations, the age alone or the genetic breed might have an effect in the spread and intensity of an experimental C. jejuni infection in vivo. Therefore, two complete diets with or without 2% lauric acid from palm kernel fatty acids were offered to 450 chickens (ten subgroups à 15 birds, repetitions: n = 3) of two broiler and two layer breeds (Ross 308, Hubbard JA 757, Lohmann Dual and Lohmann Brown-Classic). All breeds were reared for 42 days, Lohmann Brown-Classic also for about 98 days. Twenty-one days before dissection, three seeder birds per subgroup were orally infected with a 1 mL inoculum of C. jejuni (4.46±0.35 log10 CFU/mL). Qualitative detection of C. jejuni in cloacal swabs was performed at days 2, 4, 7, 14 after inoculation and at dissection in all birds. Quantitative detection was performed on excreta samples of seeder birds at days 2, 11 and 17 after experimental challenge and on caecal samples of all birds at dissection. Two days after experimental inoculation, C. jejuni prevalence was higher in control birds without lauric acid supplementation (48.9% vs. 39.6%; P = 0.0462). Depending on age, two days after inoculation the C. jejuni prevalence in young Lohmann Brown-Classic chickens was significantly lower (37.8% vs. 61.1%) whereas at dissection it was higher (99% vs. 67%). At day 2 after inoculation C. jejuni counts in the excreta of young Lohmann Brown-Classic were lower in comparison to those in old ones (log10 CFU/g: 3.30±2.68 vs. 5.24±1.56). Eleven (log10 CFU/g: 5.14±1.13 vs. 4.16±0.82) and 17 days after inoculatioin (log10 CFU/g: 3.77±2.02 vs. 1.72±1.87) it was the reverse situation. At dissection, the carriage of C. jejuni in caecal content was higher in younger than in older birds (log10 CFU/g: 8.57±0.46 vs. 6.66±1.43). An effect of genetic breed on C. jejuni prevalence was seen at dissection, this being lowest in Lohmann Dual chickens (91% vs. 98.9% in other breeds). At d 17 after challenge, C. jejuni counts in the excreta of young Lohmann Brown-Classic were lower in comparison to Ross 308 and Hubbard JA 757 (log10 CFU/g: 3.77±2.02 vs. 5.21±0.85 and 5.62±0.90). Lohmann Dual chickens showed an intermediary excretion, this being only significant lower compared to Hubbard JA 757 (log10 CFU/g: 4.31±0.89). In summary, the effect of lauric acid is limited to the initial phase after experimental inoculation. A higher age at infection seems to lead to a more rapid limitation of the infection. The excretion of C. jejuni appears to decrease more rapidly in layer breeds than in broiler lines after experimental inoculation.

Soluble nondigestible carbohydrates improve intestinal function and increase caecal coliform load in broiler chickens

Diets rich in various soluble nondigestible carbohydrates (sNDCs) were evaluated on different intestinal characteristics (histological, physico-chemical and microbiological) of chickens and compared with a maize-based diet as a control. A total of 160 Ross 308 male chickens were kept in deep litter pens (n = 40) and fed their appropriate diets from Day 1 to Day 35 of life. Four isocaloric and isonitrogenous diets, differing in their sNDC content, were composed; control (containing maize as the only cereal), maize-wheat-based (M + W) and maize-based supplemented with either 20 g/kg inulin (M + I) or 30 g/kg lactose (M + L). All of the diets tested decreased ileal crypt depth, ileal muscle layer thickness and increased caecal coliform counts relative to the control group. Villus-crypt ratio increased only in the M + L group. Ileal digesta of chickens fed the M + W diet had the highest ileal viscosity and the highest caecal butyrate, valerate and total short-chain fatty acid concentrations while the lowest pH was observed in caecal contents of chickens fed the M + I diet. The diet had no effect on ileal or caecal goblet cell and intraepithelial lymphocyte numbers. Lactobacillus counts in the caecal content remained unchanged. According to the present study, various sNDC sources may have beneficial gut health effects, however, some of the intestinal variables are dependent on the type of sNDCs.

Dietary sodium butyrate improves intestinal development and function by modulating the microbial community in broilers

This study investigated the effects of dietary sodium butyrate (SB) supplementation, provided as a specially coated product, on growth performance, intestinal development, morphological structure and function in broilers. In total, 720 one-day-old Arbor Acres male broilers were randomly allocated into six treatment groups with six replicates each and then fed basal diets (control) supplemented with 0, 200, 400, 800 or 1000 mg/kg of SB or with antibiotics (100 mg/kg aureomycin and 20 mg/kg colistin sulfate). The growth trial lasted for 42 days. No differences (P>0.05) in growth performance were detected between groups during the grower period (1–21 d) or over the total (1–42 d) trial period, whereas the addition of SB improved the intestinal structure by stimulating (P<0.05) goblet cells on jejunal and ileal villi accompanied by a trend towards increased (P_diets<0.10) ileal villus height. In addition, more inerratic leaf-shaped villi and mucus secretion and significantly fewer erosions were demonstrated by scanning electron microscopy. Apart from decreased (P<0.05) malondialdehyde (MDA) in the ileal mucosa at 21 d of age, supplemental SB at higher doses (800 mg/kg) led to greater (P<0.05) total antioxidant capacity and depressed (P<0.05) MDA concentrations in the jejunal mucosa. Birds fed with 400 mg/kg and 800 mg/kg SB had higher (P<0.05) acetic acid concentrations at 42 d and higher butyric acid at 21 d in the jejunum chyme. Morever, chicks fed SB diet were found to have higher concentrations of butyric acid (P<0.05) in the ileal chyme. SB additions at 400 mg/kg displayed higher Firmicutes and Proteobacteria levels, while a higher (P<0.05) relative abundance of Bacteroidetes was observed at 800 mg/kg. Furthermore, we found a striking decrease in Enterobacteriaceae and increases in Lachnospiraceae and Rikenellaceae in the cecal lumen of birds fed 800 mg/kg SB as well as a higher proportion of Ruminococcaceae and a noticeable reduction (P<0.05) of Lactobacillaceae in birds treated with 400 mg/kg SB. Taken together, our results support the importance of SB in improving the intestinal development, morphological structure and biological functions of broilers through modulation of the microbial community, which seems to be optimized for gut health at higher doses (800 mg/kg) of SB.

Current Perspectives of the Chicken Gastrointestinal Tract and Its Microbiome

The microbial communities inhabiting the gastrointestinal tract (GIT) of chickens are essential for the gut homeostasis, the host metabolism and affect the animals' physiology and health. They play an important role in nutrient digestion, pathogen inhibition and interact with the gut-associated immune system. Throughout the last years high-throughput sequencing technologies have been used to analyze the bacterial communities that colonize the different sections of chickens' gut. The most common methodologies are targeted amplicon sequencing followed by metagenome shotgun sequencing as well as metaproteomics aiming at a broad range of topics such as dietary effects, animal diseases, bird performance and host genetics. However, the respective analyses are still at the beginning and currently there is a lack of information in regard to the activity and functional characterization of the gut microbial communities. In the future, the use of multi-omics approaches may enhance research related to chicken production, animal and also public health. Furthermore, combinations with other disciplines such as genomics, immunology and physiology may have the potential to elucidate the definition of a "healthy" gut microbiota.

Coadministration of the Campylobacter jejuni N-Glycan-Based Vaccine with Probiotics Improves Vaccine Performance in Broiler Chickens

Source attribution studies report that the consumption of contaminated poultry is the primary source for acquiring human campylobacteriosis. Oral administration of an engineered Escherichia coli strain expressing the Campylobacter jejuni N-glycan reduces bacterial colonization in specific-pathogen-free leghorn chickens, but only a fraction of birds respond to vaccination. Optimization of the vaccine for commercial broiler chickens has great potential to prevent the entry of the pathogen into the food chain. Here, we tested the same vaccination approach in broiler chickens and observed similar efficacies in pathogen load reduction, stimulation of the host IgY response, the lack of C. jejuni resistance development, uniformity in microbial gut composition, and the bimodal response to treatment. Gut microbiota analysis of leghorn and broiler vaccine responders identified one member of Clostridiales cluster XIVa, Anaerosporobacter mobilis, that was significantly more abundant in responder birds. In broiler chickens, coadministration of the live vaccine with A. mobilis or Lactobacillus reuteri, a commonly used probiotic, resulted in increased vaccine efficacy, antibody responses, and weight gain. To investigate whether the responder-nonresponder effect was due to the selection of a C. jejuni "supercolonizer mutant" with altered phase-variable genes, we analyzed all poly(G)-containing loci of the input strain compared to nonresponder colony isolates and found no evidence of phase state selection. However, untargeted nuclear magnetic resonance (NMR)-based metabolomics identified a potential biomarker negatively correlated with C. jejuni colonization levels that is possibly linked to increased microbial diversity in this subgroup. The comprehensive methods used to examine the bimodality of the vaccine response provide several opportunities to improve the C. jejuni vaccine and the efficacy of any vaccination strategy.IMPORTANCE Campylobacter jejuni is a common cause of human diarrheal disease worldwide and is listed by the World Health Organization as a high-priority pathogen. C. jejuni infection typically occurs through the ingestion of contaminated chicken meat, so many efforts are targeted at reducing C. jejuni levels at the source. We previously developed a vaccine that reduces C. jejuni levels in egg-laying chickens. In this study, we improved vaccine performance in meat birds by supplementing the vaccine with probiotics. In addition, we demonstrated that C. jejuni colonization levels in chickens are negatively correlated with the abundance of clostridia, another group of common gut microbes. We describe new methods for vaccine optimization that will assist in improving the C. jejuni vaccine and other vaccines under development.

Effects of dry whey powder and calcium butyrate supplementation of corn/soybean-based diets on productive performance, duodenal histological integrity, and Campylobacter colonization in broilers

BACKGROUND

Campylobacter is the main cause of gastroenteritis in humans in industrialized countries, and poultry is its principal reservoir and source of human infections. Dietary supplementation of broiler feed with additives could improve productive performance and elicit health benefits that might reduce Campylobacter contamination during primary production. The aim of this study was to assess the effect of dietary supplementation with whey (a prebiotic) and calcium butyrate (a salt of a short-chain fatty acid) on productive traits, duodenal histological integrity, and Campylobacter colonization and dissemination in broiler chickens during the 42-day rearing period.

RESULTS

Six hundred one-day-old Ross-308 chickens were placed into 20 ground pens and assigned to one of 4 corn/soybean-based dietary treatments (5 replicates of 30 chicks per treatment) following a randomized complete block design: 1) basal diet with no supplementation as the control, 2) diet supplemented with 6% dry whey powder, 3) diet containing 0.1% coated calcium butyrate, and 4) diet containing 6% whey and 0.1% calcium butyrate. At age 15 days, 6 chickens per pen were experimentally inoculated with Campylobacter jejuni. The results showed that supplementation of the corn/soybean-based diet with 6% whey alone or, preferably, in combination with 0.1% coated calcium butyrate improved growth and feed efficiency, had a beneficial effect on duodenal villus integrity, and decreased mortality. These favourable effects were particularly significant during the starter period. Six days after oral challenge, Campylobacter was widespread in the flock, and the birds remained positive until the end of the rearing period. Although Campylobacter was not isolated from environmental samples, it was detected by real-time polymerase chain reaction (PCR) in dust, air filters, and drinkers while birds shed culturable C. jejuni cells. No differences (p > 0.050) in colonization or shedding levels that could be attributed to the diet were observed during the assay.

CONCLUSIONS

Beneficial effects on performance and intestinal health were observed, particularly during the starter period, when chickens were fed a diet supplemented with both whey and coated calcium butyrate. However, none of the tested diets provided the chicks any differential degree of protection against Campylobacter infection.

Differences in host breed and diet influence colonization by Campylobacter jejuni and induction of local immune responses in chicken

BACKGROUND

Chickens are regarded as the main reservoir for human campylobacteriosis. Little is known about the interaction between Campylobacter jejuni (C. jejuni) and chickens. This interaction may be influenced by the stage of maturation of the immune system, developing gut microbiota composition and other factors including breed and diet. Our aim was to investigate the impact of breed, and diet on C. jejuni colonization and host immune responses in chickens. Birds were inoculated with 10⁴ colony forming units (CFU) of C. jejuni or diluent at one (Exp. 1) or 22 (Exp. 2) days post hatch. We compared local immune cell subpopulations, cytokine expression levels, and gut microbiota composition between broiler-type (BT) and layer-type (LT) birds fed with either commercial broiler feed (bf) or layer feed (lf).

RESULTS

Lower colonization rates were observed in the older age group independent of breed and diet. Independent of breed, birds fed with bf showed higher CFU of C. jejuni compared to lf-fed groups. Campylobacter jejuni-inoculation had a significant effect on lymphocyte numbers and cytokine expression levels in BT birds independent of feeding strategy (p < 0.05). These effects were not detected in LT birds, only LT birds fed with bf showed a significant increase in IL-8-expression at 7 days post C. jejuni inoculation compared to LT-control birds (p < 0.05). Diet influenced gut microbiota composition in a comparable manner between BT and LT birds, but changes in microbiota composition associated with C. jejuni inoculation varied between breeds.

CONCLUSIONS

Diet and breed influenced C. jejuni colonization, immune responses and microbiota composition to a different extent comparing between LT and BT birds. The mechanisms behind these differences have to be elucidated further. Our results suggest that selection for more resistant breeds in combination with adapted feeding strategies may help to reduce Campylobacter colonization levels in commercial poultry in the future.

Differential modulation of flagella expression in enterohaemorrhagic Escherichia coli O157: H7 by intestinal short-chain fatty acid mixes

During passage through the gastrointestinal tract, enterohaemorrhagic Escherichia coli (EHEC) encounters numerous stresses, each producing unique antimicrobial conditions. Beyond surviving these stresses, EHEC may also use them as cues about the local microenvironment to modulate its virulence. Of particular interest is how exposure to changing concentrations of short-chain fatty acids (SCFAs) associated with passage through the small and large intestines affects EHEC virulence, as well as flagella expression and motility specifically. In this study, we investigate the impact of exposure to SCFA mixes simulating concentrations and compositions within the small and large intestines on EHEC flagella expression and function. Using a combination of DNA microarray, quantitative real-time PCR, immunoblot analysis, flow cytometry and motility assays, we show that there is a marked, significant upregulation of flagellar genes, the flagellar protein, FliC, and motility when EHEC is exposed to SCFA mixes representative of the small intestine. By contrast, when EHEC is exposed to SCFA mixes representative of the large intestine, there is a significant downregulation of flagellar genes, FliC and motility. Our results demonstrate that EHEC modulates flagella expression and motility in response to SCFAs, with differential responses associated with SCFA mixes typical of the small and large intestines. This research contributes to our understanding of how EHEC senses and responds to host environmental signals and the mechanisms it uses to successfully infect the human host. Significantly, it also suggests that EHEC is using this key gastrointestinal chemical signpost to cue changes in flagella expression and motility in different locations within the host intestinal tract.

Thermotolerant Campylobacter during Broiler Rearing: Risk Factors and Intervention

Thermotolerant Campylobacters are one of the most important bacterial causative agents of human gastrointestinal illness worldwide. In most European Union (EU) member states human campylobacteriosis is mainly caused by infection with Campylobacter jejuni or Campylobacter coli following consumption or inadequate handling of Campylobacter-contaminated poultry meat. To date, no effective strategy to control Campylobacter colonization of broilers during rearing is available. In this review, we describe the public health problem posed by Campylobacter presence in broilers and list and critically review all currently known measures that have been researched to lower the numbers of Campylobacter bacteria in broilers during rearing. We also discuss the most promising measures and which measures should be investigated further. We end this review by elaborating on readily usable measures to lower Campylobacter introduction and Campylobacter numbers in a broiler flock.

Composition of diet modifies colonization dynamics of Campylobacter jejuni in broiler chickens

AIMS

To evaluate the impact of diet composition on colonization dynamics of Camp. jejuni and on related physiological parameters in the chicken intestine.

METHODS AND RESULTS

A total of 54 1-day-old Ross 308 broiler chicks were randomly divided into three isocaloric and isonitrogenous dietary groups: maize-based (MB), wheat-based (WB) diet and wheat-based diet with NSP-degrading enzyme supplementation (WBES). Chickens were orally infected with 10(8)  CFU Camp. jejuni on day 14, and samples (n = 6) were collected on 7, 14 and 21 days postinfection (DPI), respectively. Colony forming units of Camp. jejuni of caecum and jejunum, short-chain fatty acid (SCFA) concentrations, pH values of the caecum, jejunal histomorphology and viscosity of jejunal chymus were measured. In case of WBES diet, lower Camp. jejuni colonization 14 DPI, higher jejunal viscosity, higher total SCFA concentrations in the caecum and enhanced jejunal histomorphology were observed compared to those measured in chickens fed MB diet.

CONCLUSIONS

The WBES diet altered Camp. jejuni colonization dynamics in the chicken intestine which resulted by higher SCFA concentrations in the caecum and by the change of gut morphology.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our study proves that diet composition can modify Camp. jejuni colonization depending on sampling time point postinfection.

Dietary fatty acids and immune response to food-borne bacterial infections

Functional innate and acquired immune responses are required to protect the host from pathogenic bacterial infections. Modulation of host immune functions may have beneficial or deleterious effects on disease outcome. Different types of dietary fatty acids have been shown to have variable effects on bacterial clearance and disease outcome through suppression or activation of immune responses. Therefore, we have chosen to review research across experimental models and food sources on the effects of commonly consumed fatty acids on the most common food-borne pathogens, including Salmonella sp., Campylobacter sp., Shiga toxin-producing Escherichia coli, Shigella sp., Listeria monocytogenes, and Staphylococcus aureus. Altogether, the compilation of literature suggests that no single fatty acid is an answer for protection from all food-borne pathogens, and further research is necessary to determine the best approach to improve disease outcomes.