Effect of an Enterococcus faecium probiotic on specific IgA following live Salmonella Enteritidis vaccination of layer chickens

Host genetics drives differences in cecal microbiota composition and immune traits of laying hens raised in the same environment

Vaccination is one of the most effective strategies for preventing infectious diseases but individual vaccine responses are highly heterogeneous. Host genetics and gut microbiota composition are 2 likely drivers of this heterogeneity. We studied 94 animals belonging to 4 lines of laying hens: a White Leghorn experimental line genetically selected for a high antibody response against the Newcastle Disease Virus (NDV) vaccine (ND3) and its unselected control line (CTR), and 2 commercial lines (White Leghorn [LEG] and Rhode Island Red [RIR]). Animals were reared in the same conditions from hatching to 42 d of age, and animals from different genetic lines were mixed. Animals were vaccinated at 22 d of age and their humoral vaccine response against NDV was assessed by hemagglutination inhibition assay and ELISA from blood samples collected at 15, 19, and 21 d after vaccination. The immune parameters studied were the 3 immunoglobulins subtypes A, M, and Y and the blood cell composition was assessed by flow cytometry. The composition of the cecal microbiota was assessed at the end of the experiment by analyzing amplified 16S rRNA gene sequences to obtain amplicon sequence variants (ASV). The 4 lines showed significantly different levels of NDV vaccine response at the 3 measured points, with, logically, a higher response of the genetically selected ND3 line, and intermediate and low responses for the unselected CTR control line and for the 2 commercial lines, respectively. The ND3 line displayed also a higher proportion of immunoglobulins (IgA, IgM, and IgY). The RIR line showed the most different blood cell composition. The 4 lines showed significantly different microbiota characteristics: composition, abundances at all taxonomic levels, and correlations between genera and vaccine response. The tested genetic lines differ for immune parameters and gut microbiota composition and functions. These phenotypic differences can be attributed to genetic differences between lines. Causal relationships between both types of parameters are discussed and will be investigated in further studies.

Unveiling nanotubes-mediated communication: Enterococcus faecalis countering Salmonella ser. Typhi - In vitro and In vivo insights

Bacteria communicate with each other through contact-dependent and contact-independent mechanisms. While certain contact-dependent mechanisms, such as Type IV and Type VI, have received considerable attention, nanotubes-mediated communication among gut bacteria remains largely unknown. The purpose of this study is to demonstrate the presence of nanotube production in both gut commensal and gut pathogenic bacteria. And also aims to show how Enterococcus faecalis utilizes nanotubes to combat Salmonella ser. Typhi (S. Typhi), a pathogen in the gut. The research findings suggest that the formation of nanotubes is an inherent trait observed in both Gram-positive and Gram-negative bacteria. Interestingly, bacteria generate nanotubes in dynamic environments, biofilms, and even within the gut of zebrafish. These nanotubes develops over time in accordance with the duration of incubation. Furthermore, E. faecalis effectively combats S. Typhi through mechanisms that depend on physical contact rather than indirect methods. Notably, E. faecalis protects zebrafish larvae from S. Typhi infections by reducing reactive oxygen species and cell death, and concurrently boosting the production of antioxidant enzymes. It is hypothesized that E. faecalis might eliminate S. Typhi by transferring toxic metabolites into the pathogen via nanotubes. Gene expression analysis highlights that proinflammatory markers such as TNF-α, IL-1β, and IL-6 are elevated in Salmonella-infected larvae. However, co-treatment with E. faecalis counters this effect. Findings of this study underscores the significance of nanotubes as a vital machinery for bacterial communication and distribution of virulence factors. Exploring nanotubes-mediated communication at a molecular level could pave the way for innovative therapeutic interventions.

Effects of a Specific Pre- and Probiotic Combination and Parent Stock Vaccination on Performance and Bacterial Communities in Broilers Challenged with a Multidrug-Resistant Escherichia coli

Antibiotic resistance poses a risk for human and animal health, leading to a growing demand for effective alternatives. Combining nutritional tools and parent stock vaccination could be an approach to achieve sufficient protection against bacterial infections in poultry. In an Escherichia coli O1/O18 challenge trial, we investigated the protective effects of feeding diets containing Enterococcus faecium DSM 7134 and fructooligosaccharides (FOS) combined with specific parent stock vaccination in 225 ROSS 308 broilers. Data on performance parameters, intestinal microbial composition and metabolites, and antibiotic resistance genes (sul1-3, dhfr1a, SHV-12) were obtained. E. faecium and FOS combined with parent stock vaccination led to the highest body weights, which were significantly higher than those of controls throughout the experiment and decreased the relative abundance of Proteobacteria in the crop digesta compared to that in the positive control. However, cumulative feed conversation remained unaffected by the strategies. Birds receiving the pre-/probiotic combination showed lower cecal pH levels and higher crop L-lactate concentrations than the controls, whereas copy numbers of dhfr1a (trimethoprim resistance) and SHV-12 (extended-spectrum beta-lactamase) genes were only decreased in broilers from vaccinated hens compared to those in the challenged control. In conclusion, prophylactic administration of E. faecium and FOS in combination with parent stock vaccination can have complementary effects by improving broiler weight gain and stimulating intestinal bacterial metabolism, which may be beneficial for maintaining gut health in terms of Escherichia coli infection.

Pretreatment with probiotics Enterococcus faecium NCIMB 11181 attenuated Salmonella Typhimurium-induced gut injury through modulating intestinal microbiome and immune responses with barrier function in broiler chickens

Background

Preventing Salmonella infection and colonization in young birds is key to improving poultry gut health and reducing Salmonella contamination of poultry products and decreasing salmonellosis for human consumption (poultry meat and eggs). Probiotics can improve poultry health. The present study was conducted to investigate the impact of a probiotics, Enterococcus faecium NCIMB 11181 (E. faecium NCIMB 11181) on the intestinal mucosal immune responses, microbiome and barrier function in the presence or absence of Salmonella Typhimurium (S. Typhimurium, ST) infection.

Methods

Two hundred and forty 1-day-old Salmonella-free male broiler chickens (Arbor Acres AA⁺) were randomly allocated to four groups with 6 replicate cages of 10 birds each. The four experimental groups were follows: (1) negative control (NC), (2) S. Typhimurium, challenged positive control (PC), (3) the E. faecium NCIMB 11181-treated group (EF), (4) the E. faecium NCIMB 11181-treated and S. Typhimurium-challenged group (PEF).

Results

Results indicated that, although continuous feeding E. faecium NCIMB 11181 did not obviously alleviate growth depression caused by S. Typhimurium challenge (P > 0.05), E. faecium NCIMB 11181 addition significantly blocked Salmonella intestinal colonization and translocation (P < 0.05). Moreover, supplemental E. faecium NCIMB 11181 to the infected chickens remarkably attenuated gut morphological structure damage and intestinal cell apoptosis induced by S. Typhimurium infection, as evidenced by increasing gut villous height and reducing intestinal TUNEL-positive cell numbers (P < 0.05). Also, E. faecium NCIMB 11181 administration notably promoting the production of anti-Salmonella antibodies in intestinal mucosa and serum of the infected birds (P < 0.05). Additionally, 16S rRNA sequencing analysis revealed that E. faecium NCIMB 11181 supplementation ameliorated S. Typhimurium infection-induced gut microbial dysbiosis by enriching Lachnospiracease and Alistipes levels, and suppressing Barnesiella abundance. Predicted function analysis indicated that the functional genes of cecal microbiome involved in C5-branched dibasic acid metabolism; valine, leucine and isoleucine biosynthesis; glycerolipid metabolism and lysine biosynthesis were enriched in the infected chickens given E. faecium NCIMB 11181. While alanine, asparate and glutamate metabolism; MAPK signal pathway-yeast; ubiquine and other terpenoid-quinore biosynthesis, protein processing in endoplasmic reticulum; as well as glutathione metabolism were suppressed by E. faecium NCIMB 11181 addition.

Conclusion

Collectively, our data suggested that dietary E. faecium NCIBM 11181 supplementation could ameliorate S. Typhimurium infection-induced gut injury in broiler chickens. Our findings also suggest that E. faecium NCIMB 11181 may serve as an effective non-antibiotic feed additive for improving gut health and controlling Salmonella infection in broiler chickens.

An updated review on probiotics as an alternative of antibiotics in poultry - A review

Antibiotics used to be supplemented to animal feeds as growth promoter and as an effective strategy to reduce the burden of pathogenic bacteria present in the gastro-intestinal tract. However, in-feed antibiotics also kill bacteria that may be beneficial to the animal. Secondly, unrestricted use of antibiotics enhanced the antibiotic resistance in pathogenic bacteria. To overcome above problems, scientists are taking a great deal of measures to develop alternatives of antibiotics. There is convincing evidence that probiotics could replace in-feed antibiotics in poultry production. Because they have beneficial effects on growth performance, meat quality, bone health and eggshell quality in poultry. Better immune responses, healthier intestinal microflora and morphology which help the birds to resist against disease attack were also identified with the supplementation of probiotics. Probiotics establish cross-feeding between different bacterial strains of gut ecosystem and reduce the blood cholesterol level via bile salt hydrolase activity. The action mode of probiotics was also updated according to recently published literatures, i.e antimicrobial substances generation or toxin reduction. This comprehensive review of probiotics is aimed to highlight the beneficial effects of probiotics as a potential alternative strategy to replace the antibiotics in poultry.

Comparison of Therapeutic Antibiotics, Probiotics, and Synthetic CpG-ODNs for Protective Efficacy Against Escherichia coli Lethal Infection and Impact on the Immune System in Neonatal Broiler Chickens

The poultry industry needs alternatives to antibiotics, as there are growing public concerns about the emergence of antimicrobial resistance owing to antimicrobial use in animal production. We have reported that the administration of neonatal chicks with synthetic DNA oligodeoxynucleotides containing unmethylated cytosine guanine dinucleotide (CpG) motifs (CpG-ODN) can protect against bacterial pathogens in chickens. The objective of this study was to compare the immunoprotective effects of CpG-ODN and probiotics against Escherichia coli infection vs. commonly used therapeutic antibiotics. Day-old broiler chicks were divided into five groups (n = 35/group; 30 for the challenge experiment and 5 for the flow cytometry analysis). The chicks in Group 1 received a single dose of CpG-ODN by the intramuscular route on day 4 (D4) posthatch (PH), and Group 2 received drinking water (DW) with a probiotic product (D1-D15 PH, DW). The Group 3 chicks received tetracycline antibiotics during D9-D13 in DW; the Group 4 chicks got sodium sulfamethazine on D9, D10, and D15 PH in DW; and the Group 5 chicks were administered intramuscular (IM) saline D4 PH, DW. We challenged all the groups (n = 30/group) with E. coli (1 × 10⁵ or 1 × 10⁶ colony-forming units/bird) on D8 PH through the subcutaneous route. Our data demonstrated that the CpG-ODNs, but not the probiotics, could protect neonatal broiler chickens against lethal E. coli septicemia, as would the tetracycline or sodium sulfamethazine. The flow cytometry analysis (n = 5/group) revealed enrichment of immune cells in the CpG-ODN group and a marked decrease in macrophages and T-cell numbers in antibiotics-treated groups, indicating immunosuppressive effects. Our data showed that, like therapeutic antibiotics, CpG-ODNs reduced clinical signs, decreased bacterial loads, and induced protection in chicks against E. coli septicemia. Unlike therapeutic antibiotics-induced immunosuppressive effects, CpG-ODN caused immune enrichment by increasing chicken immune cells recruitment. Furthermore, this study highlights that, although therapeutic antibiotics can treat bacterial infections, the ensuing immunosuppressive effects may negatively impact the overall chicken health.

The control of poultry salmonellosis using organic agents: an updated overview

Salmonellosis is a severe problem that threatens the poultry sector worldwide right now. Salmonella gallinarium and Salmonella pullorum (Fowl typhoid) are the most pathogenic serovars in avian species leading to systemic infection resulting in severe economic losses in the poultry industry. Nontyphoidal serotypes of Salmonella (Paratyphoid disease) constitute a public health hazard for their involvement in food poisoning problems in addition to their zoonotic importance. Also, Salmonella species distribution is particularly extensive. They resisted environmental conditions that made it difficult to control their spread for a long time. Therefore, the current review aimed to through light on Salmonellosis in poultry with particular references to its pathogenesis, economic importance, immune response to Salmonella, Salmonella antibiotics resistance, possible methods for prevention and control of such problems using promising antibiotics alternatives including probiotics, prebiotics, symbiotics, organic acids, essential oils, cinnamaldehyde, chitosan, nanoparticles, and vaccines.

Influence of Immune Parameters after Enterococcus faecium AL41 Administration and Salmonella Infection in Chickens

Immune response of day-old chicks infected with Salmonella Enteritidis PT4 and preventive administration of Enterococcus faecium AL41 were studied using hematology and flow cytometry of immunocompetent cells in blood, cecum, bursa and spleen for 11 days, and included 220 animals divided into four groups (n = 55). E. faecium AL41 was administered for 7 days to EF and EFSE groups and on day 4 SE and EFSE groups were infected with Salmonella Enteritidis. Values of monocytes at 4 dpi significantly increased in EFSE and lymphocytes at 7 dpi in EF groups. Blood CD3, CD4, CD8 and IgM lymphocytes improved in EF and EFSE groups and IgA in EF group at 4 dpi. Phagocytic activity of probiotic groups was improved in both samples. Cecal IEL and LPL lymphocytes showed at 7 dpi stimulation of CD3, CD4 and CD8 subpopulations in probiotic groups, especially in EFSE group, IgA IEL and IgA with IgM LPL in EF groups. Bursa Fabricii at 7 dpi presented overstimulation of IgG subpopulation in SE group, spleen CD3 and CD8 in EF and EFSE groups. E. faecium AL41 revealed the protective effect and positive influence on the local and systemic immune response in Salmonella Enteritidis PT4 infected chickens.

Non-Antibiotics Strategies to Control Salmonella Infection in Poultry

Salmonella spp. is a facultative intracellular pathogen causing localized or systemic infections, involving economic and public health significance, and remains the leading pathogen of food safety concern worldwide, with poultry being the primary transmission vector. Antibiotics have been the main strategy for Salmonella control for many years, which has allowed producers to improve the growth and health of food-producing animals. However, the utilization of antibiotics has been reconsidered since bacterial pathogens have established and shared a variety of antibiotic resistance mechanisms that can quickly increase within microbial communities. The use of alternatives to antibiotics has been recommended and successfully applied in many countries, leading to the core aim of this review, focused on (1) describing the importance of Salmonella infection in poultry and the effects associated with the use of antibiotics for disease control; (2) discussing the use of feeding-based (prebiotics, probiotics, bacterial subproducts, phytobiotics) and non-feeding-based (bacteriophages, in ovo injection, vaccines) strategies in poultry production for Salmonella control; and (3) exploring the use of complementary strategies, highlighting those based on -omics tools, to assess the effects of using the available antibiotic-free alternatives and their role in lowering dependency on the existing antimicrobial substances to manage bacterial infections in poultry effectively.

Immunosecurity: immunomodulants enhance immune responses in chickens

The global population has increased with swift urbanization in developing countries, and it is likely to result in a high demand for animal-derived protein-rich foods. Animal farming has been constantly affected by various stressful conditions, which can be categorized into physical, environmental, nutritional, and biological factors. Such conditions could be exacerbated by banning on the use of antibiotics as a growth promoter together with a pandemic situation including, but not limited to, African swine fever, avian influenza, and foot-and-mouth disease. To alleviate these pervasive tension, various immunomodulants have been suggested as alternatives for antibiotics. Various studies have investigated how stressors (i.e., imbalanced nutrition, dysbiosis, and disease) could negatively affect nutritional physiology in chickens. Importantly, the immune system is critical for host protective activity against pathogens, but at the same time excessive immune responses negatively affect its productivity. Yet, comprehensive review articles addressing the impact of such stress factors on the immune system of chickens are scarce. In this review, we categorize these stressors and their effects on the immune system of chickens and attempt to provide immunomodulants which can be a solution to the aforementioned problems facing the chicken industry.

Live Bacterial Prophylactics in Modern Poultry

Commercial poultry farms frequently use live bacterial prophylactics like vaccines and probiotics to prevent bacterial infections. Due to the emergence of antibiotic-resistant bacteria in poultry animals, a closer examination into the health benefits and limitations of commercial, live prophylactics as an alternative to antibiotics is urgently needed. In this review, we summarize the peer-reviewed literature of several commercial live bacterial vaccines and probiotics. Per our estimation, there is a paucity of peer-reviewed published research regarding these products, making repeatability, product-comparison, and understanding biological mechanisms difficult. Furthermore, we briefly-outline significant issues such as probiotic-label accuracy, lack of commercially available live bacterial vaccines for major poultry-related bacteria such as Campylobacter and Clostridium perfringens, as well research gaps (i.e., probiotic-mediated vaccine adjuvancy, gut-brain-microbiota axis). Increased emphasis on these areas would open several avenues for research, ranging from improving protection against bacterial pathogens to using these prophylactics to modulate animal behavior.

Yeast cell wall product enhanced intestinal IgA response and changed cecum microflora species after oral vaccination in chickens

The study was designed to explore the effect of a commercial yeast cell wall product (YP) on chicken intestinal IgA response and cecum microbiome after oral vaccination. Chickens were fed with YP during the experiments and orally immunized with live Newcastle disease virus (NDV) vaccine at 2 wk of age. Then, the animals were sacrificed, and samples were collected to measure the indicators of hemagglutination inhibition (HI), IgA response, IgA + cells, and cecum microbiome populations. The results showed that supplement of YP significantly enhanced serum NDV HI titer, intestinal NDV-specific secretory IgA, and intestinal IgA + cells. The sequencing results revealed that obviously increased relative abundance of Ruminococcaceae and decreased population of Bacteroidaceae in cecum were found in YP group. In summary, YP supplementation in diet enhanced intestinal IgA response to NDV vaccination by oral route and modulated the cecum microbiota to the advantage of the host in chickens.

Efficacy of probiotic Enterococcus faecium in combination with diclazuril against coccidiosis in experimentally infected broilers

AIMS

The study was conducted to investigate the combination of a probiotic strain of Enterococcus faecium and diclazuril to control coccidiosis in broilers.

METHODS AND RESULTS

A total of 240 one-day-old female broiler chicks were divided into eight groups (30 chicks per group): prophylactic groups (G1, G2 and G3) and therapeutic groups (G4, G5 and G6) and two control groups (untreated infected, G7 and untreated uninfected, G8 controls). In the prophylactic approach, diclazuril alone (G1), probiotic alone (G2) or a mixture of both probiotic and diclazuril (G3) was orally administered to the chicks via drinking water 10 days prior to the infection. However, in the therapeutic approach, G4, G5 and G6 birds were administered diclazuril alone, probiotic alone and diclazuril+probiotic mix, respectively, in drinking water for five consecutive days after the appearance of clinical signs of coccidiosis. Birds of both approaches and G7 were experimentally infected with 25 × 10³ Eimeria-sporulated oocysts. Chicks in G3 showed the highest weight gain, the lowest lesion score, a low oocyst count and mortality rate among the challenged groups. Moderate lesion scores and oocyst counts were observed in chickens administered probiotics prophylactically. In the therapeutic approach, broilers in G6 but not G5 displayed a decreased mortality rate and lesion score in comparison to those in G7 and G8. However, the result of the probiotic-treated group was not significantly different from that in the untreated infected control group.

CONCLUSION

The probiotic supplementation as a prophylactic approach can decrease the adverse effects of eimerian infection. In addition, the probiotic and diclazuril mix achieved a considerable improvement in the growth performance. Therefore, probiotic plus diclazuril combination achieved a synergistic effect.

SIGNIFICANCE AND IMPACT OF THE STUDY

Investigation into the synergism/antagonism between a probiotic and diclazuril as anticoccidial agent and the difference in the timing of administration.

Effects of GABA Supplementation on Intestinal SIgA Secretion and Gut Microbiota in the Healthy and ETEC-Infected Weanling Piglets

Pathogenic enterotoxigenic Escherichia coli (ETEC) has been considered a major cause of diarrhea which is a serious public health problem in humans and animals. This study was aimed at examining the effect of γ-aminobutyric acid (GABA) supplementation on intestinal secretory immunoglobulin A (SIgA) secretion and gut microbiota profile in healthy and ETEC-infected weaning piglets. A total of thirty-seven weaning piglets were randomly distributed into two groups fed with the basal diet or supplemented with 40 mg·kg-1 of GABA for three weeks, and some piglets were infected with ETEC at the last week. According to whether ETEC was inoculated or not, the experiment was divided into two stages (referred as CON1 and CON2 and GABA1 and GABA2). The growth performance, organ indices, amino acid levels, and biochemical parameters of serum, intestinal SIgA concentration, gut microbiota composition, and intestinal metabolites were analyzed at the end of each stage. We found that, in both the normal and ETEC-infected piglets, jejunal SIgA secretion and expression of some cytokines, such as IL-4, IL-13, and IL-17, were increased by GABA supplementation. Meanwhile, we observed that some low-abundance microbes, like Enterococcus and Bacteroidetes, were markedly increased in GABA-supplemented groups. KEGG enrichment analysis revealed that the nitrogen metabolism, sphingolipid signaling pathway, sphingolipid metabolism, and microbial metabolism in diverse environments were enriched in the GABA1 group. Further analysis revealed that alterations in microbial metabolism were closely correlated to changes in the abundances of Enterococcus and Bacteroidetes. In conclusion, GABA supplementation can enhance intestinal mucosal immunity by promoting jejunal SIgA secretion, which might be related with the T-cell-dependent pathway and altered gut microbiota structure and metabolism.

A probiotic treatment increases the immune response induced by the nasal delivery of spore-adsorbed TTFC

Background

Spore-forming bacteria of the Bacillus genus are widely used probiotics known to exert their beneficial effects also through the stimulation of the host immune response. The oral delivery of B. toyonensis spores has been shown to improve the immune response to a parenterally administered viral antigen in mice, suggesting that probiotics may increase the efficiency of systemic vaccines. We used the C fragment of the tetanus toxin (TTFC) as a model antigen to evaluate whether a treatment with B. toyonensis spores affected the immune response to a mucosal antigen.

Results

Purified TTFC was given to mice by the nasal route either as a free protein or adsorbed to B. subtilis spores, a mucosal vaccine delivery system proved effective with several antigens, including TTFC. Spore adsorption was extremely efficient and TTFC was shown to be exposed on the spore surface. Spore-adsorbed TTFC was more efficient than the free antigen in inducing an immune response and the probiotic treatment improved the response, increasing the production of TTFC-specific secretory immunoglobin A (sIgA) and causing a faster production of serum IgG. The analysis of the induced cytokines indicated that also the cellular immune response was increased by the probiotic treatment. A 16S RNA-based analysis of the gut microbial composition did not show dramatic differences due to the probiotic treatment. However, the abundance of members of the Ruminiclostridium 6 genus was found to correlate with the increased immune response of animals immunized with the spore-adsorbed antigen and treated with the probiotic.

Conclusion

Our results indicate that B. toyonensis spores significantly contribute to the humoral and cellular responses elicited by a mucosal immunization with spore-adsorbed TTFC, pointing to the probiotic treatment as an alternative to the use of adjuvants for mucosal vaccinations.

Composition and Function of Chicken Gut Microbiota

Simple Summary

Chickens evolved for millions of years to be hatched in a nest in contact with an adult hen. However, current commercial production of chickens is based on hatching chicks in a clean hatchery environment in the absence of adult hens. The ancestors of domestic chickens inhabited a living environment different from that used for current commercial production. Currently, the lifespan of broilers is around 5 weeks, the lifespan of egg layers is around one year while chickens can live for 15–20 years. This means that studies on chicken–microbiota interactions are of specific importance. The intestinal tract of commercially hatched chicks is gradually colonised from environmental sources only, however, if the chicks are provided experimentally with microbiota from a hen they can be colonised by adult-type microbiota from the very first days of life and become resistant to infections with pathogenic Escherichia coli, Clostridium perfringens, or Salmonella. Because of such specificities in the interactions of chickens with their gut microbiota, current knowledge in this area is critically presented in this review.

Abstract

Studies analyzing the composition of gut microbiota are quite common at present, mainly due to the rapid development of DNA sequencing technologies within the last decade. This is valid also for chickens and their gut microbiota. However, chickens represent a specific model for host–microbiota interactions since contact between parents and offspring has been completely interrupted in domesticated chickens. Nearly all studies describe microbiota of chicks from hatcheries and these chickens are considered as references and controls. In reality, such chickens represent an extreme experimental group since control chicks should be, by nature, hatched in nests in contact with the parent hen. Not properly realising this fact and utilising only 16S rRNA sequencing results means that many conclusions are of questionable biological relevance. The specifics of chicken-related gut microbiota are therefore stressed in this review together with current knowledge of the biological role of selected microbiota members. These microbiota members are then evaluated for their intended use as a form of next-generation probiotics.

The Simultaneous Administration of a Probiotic or Prebiotic with Live Salmonella Vaccine Improves Growth Performance and Reduces Fecal Shedding of the Bacterium in Salmonella-Challenged Broilers

Salmonellosis is one of the most important bacterial diseases in poultry, causing heavy economic losses, increased mortality and reduced production. The aim of this study was the comparative efficacy of a commercial probiotic and/or prebiotic with a live attenuated Salmonella Enteritidis (SE) vaccine on the protection of broiler chickens from SE challenge. The efficacy of probiotic or prebiotic products, as well as a live Salmonella Enteritidis (SE) vaccine at the 7th day of age, administered via drinking water, were evaluated for clinical protection and effects on growth performance of broiler chickens experimentally challenged with SE at the 28th day of age. The use of probiotic or prebiotic simultaneously with the live Salmonella vaccine can diminish the negative effect of live vaccine growth performance, reducing mortality rate, fecal shedding, and re-isolation of SE from liver, spleen, heart and cecum. The use of probiotic or prebiotic simultaneously with the application of the live Salmonella vaccine is a good practice to diminish the negative effect of the harmful bacteria and improve the growth performance of broilers. Thus, further studies may be carried out with layers and breeders.

Gut Anaerobes Capable of Chicken Caecum Colonisation

Chicks in commercial production are highly sensitive to enteric infections and their resistance can be increased by administration of complex adult microbiota. However, it is not known which adult microbiota members are capable of colonising the caecum of newly hatched chicks. In this study, we therefore orally inoculated chicks with pure cultures of 76 different bacterial isolates originating from chicken caecum on day 1 of life and determined their ability to colonise seven days later. The caecum of newly hatched chickens could be colonised by bacteria belonging to phyla Bacteroidetes, Proteobacteria, Synergistetes, or Verrucomicrobia, and isolates from class Negativicutes (phylum Firmicutes). On the other hand, we did not record colonisation with isolates from phyla Actinobacteria and Firmicutes (except for Negativicutes), including isolates from families Lachnospiraceae, Ruminococcaceae, Erysipelotrichaceae, and Lactobacillaceae. Representatives of genera commonly used in probiotics such as Lactobacillus, Enterococcus, or Bacillus therefore did not colonise the chicken intestinal tract after a single dose administration. Following challenge with Salmonella enterica serovar Enteritidis, the best protecting isolates increased the chicken’s resistance to S. Enteritidis only tenfold, which, however, means that none of the tested individual bacterial isolates on their own efficiently protected chicks against S. Enteritidis.

Could probiotics be the panacea alternative to the use of antimicrobials in livestock diets?

Probiotics are most frequently derived from the natural microbiota of healthy animals. These bacteria and their metabolic products are viewed as nutritional tools for promoting animal health and productivity, disease prevention and therapy, and food safety in an era defined by increasingly widespread antimicrobial resistance in bacterial pathogens. In contemporary livestock production, antimicrobial usage is indispensable for animal welfare, and employed to enhance growth and feed efficiency. Given the importance of antimicrobials in both human and veterinary medicine, their effective replacement with direct-fed microbials or probiotics could help reduce antimicrobial use, perhaps restoring or extending the usefulness of these precious drugs against serious infections. Thus, probiotic research in livestock is rapidly evolving, aspiring to produce local and systemic health benefits on par with antimicrobials. Although many studies have clearly demonstrated the potential of probiotics to positively affect animal health and inhibit pathogens, experimental evidence suggests that probiotics' successes are modest, conditional, strain-dependent, and transient. Here, we explore current understanding, trends, and emerging applications of probiotic research and usage in major livestock species, and highlight successes in animal health and performance.

Pretreatment with probiotic Enterococcus faecium NCIMB 11181 ameliorates necrotic enteritis-induced intestinal barrier injury in broiler chickens

The dysfunction of tight-junction integrity caused by necrotic enteritis (NE) is associated with decreased nutrient absorption and gut injury in broiler chickens. Although probiotic Enterococcus faecium (E. faecium) has been reported to possess immune-regulatory characteristics and can prevent diarrhea in pigs, very little information exists in relation to the specific regulatory impact of E. faecium NCIMB 11181 on NE-induced intestinal barrier injury of broiler chickens. This study was conducted to investigate the protective effects of probiotic E. faecium NCIMB 11181 on NE-induced intestinal barrier injury in broiler chickens. The study also aimed to elucidate the mechanisms that underpin these protective effects. One hundred and eighty Arbor Acres (AA) broiler chicks (one day old) were randomly assigned using a 2 × 2 factorial arrangement into two groups fed different levels of dietary E. faecium NCIMB 11181 (0 or 2 × 10⁸ CFU/kg of diet) and two disease-challenge groups (control or NE challenged). The results showed that NE induced body weight loss, intestinal lesions, and histopathological inflammation, as well as intestinal-cell apoptosis. These symptoms were alleviated following the administration of probiotic E. faecium NCIMB 11181. Pretreatment with probiotic E. faecium NCIMB 11181 significantly upregulated the expression of the Claudin-1 gene encoding a tight-junction protein. Claudin-1 and HSP70 protein expression were also increased in the jejunum regardless of NE infection. Furthermore, NE-infected birds fed with E. faecium displayed notable increases in MyD88, NF-κB, iNOS, PI3K, GLP-2, IL-1β, IL-4, and HSP70 mRNA expression. E. faecium NCIMB 11181 administration also significantly improved the animals’ intestinal microbial composition regardless of NE treatment. These findings indicated that addition of E. faecium NCIMB 11181 to poultry feed is effective in mitigating NE-induced gut injury, possibly by strengthening intestinal mucosal barrier function, as well as modulating gut microflora and intestinal mucosal immune responses.

Egg Production in Poultry Farming Is Improved by Probiotic Bacteria

Antimicrobial resistance (AMR) is one of the most serious threats for human health in the near future. Livestock has played an important role in the appearance of antibiotic-resistant bacteria, intestinal dysbiosis in farming animals, or the spread of AMR among pathogenic bacteria of human concern. The development of alternatives like probiotics is focused on maintaining or improving production levels while diminishing these negative effects of antibiotics. To this end, we supplied the potential probiotic Enterococcus faecalis UGRA10 in the diet of laying hens at a final concentration of 10⁸ Colony Forming Units per gram (CFU/g) of fodder. Its effects have been analyzed by: (i) investigating the response of the ileum and caecum microbiome; and (ii) analyzing the outcome on eggs production. During the second half of the experimental period (40 to 76 days), hens fed E. faecalis UGRA10 maintained egg production, while control animals dropped egg production. Supplementation diet with E. faecalis UGRA10 significantly increased ileum and caecum bacterial diversity (higher bacterial operational taxonomic unit richness and Faith’s diversity index) of laying hens, with animals fed the same diet showing a higher similarity in microbial composition. These results point out to the beneficial effects of E. faecalis UGRA10 in egg production. Future experiments are necessary to unveil the underlying mechanisms that mediate the positive response of animals to this treatment.

Dissect the mode of action of probiotics in affecting host-microbial interactions and immunity in food producing animals

Prophylactic antimicrobials have been widely used in food animal production with the aim to prevent infectious diseases, enhance feed efficiency, and promote growth. However, the extensive use of antimicrobials in food animal production systems has led to the emergence of antimicrobial resistant pathogens, which are potential threats to human and animal health. Probiotics have been proposed to be a promising alternative of prophylactic antimicrobials, with potential beneficial effects on the host animal by improving the balance of intestinal microbiota and host immunity. Although an increasing body of evidence shows that probiotics could directly or indirectly affect gut microbiota and host immune functions, the lack of the understanding of how probiotics influence host-microbial interaction and immunity is one of the reasons for controversial findings from many animal trials, especially in food production animals. Therefore, in this review we focused on the most recent (last ten years) studies on how gut microbiota and host immune function changes in response to probiotics in food production animals (swine, poultry, and ruminant). In addition, the relationship between microbial changes and host immune function was illustrated, and how such relationship differs among animal species was further compared. Moreover, the future directions concerning the mechanisms of how probiotics modulate host-microbial interactions and host immunity were highlighted, which may assist in the optimal supplementation strategy to maximize the efficacy of probiotics to improve animal gut health and productivity.

The role of the gut microbiome in shaping the immune system of chickens

Most animals are colonised by at least as many microbial cells as somatic cells, potentially comprising at least 100 times more genes within just the gut microbiota than the host itself. It is, therefore, evident that such a conglomeration can have a profound effect on various bodily systems, particularly the (gut) immune system. Chickens are major providers of efficiently produced protein for humans but also harbour common foodborne pathogens and are susceptible to significant and costly diseases, making a thorough understanding of the influence of the gut microbiome on the immune system very pertinent. Major colonisation of the chicken intestine occurs after hatch and this, along with subsequent microbiota composition and activity, are influenced by numerous host and environmental factors, such that each individual has a unique microbiome signature. However, both extreme (e.g. germ free) and more subtle (e.g. diet changes) microbiome modifications can profoundly impact the development of the gut immune system, particularly adaptive immune apparatus and function. This review will consider the influence of the chicken gut microbiome on immune system development, the implications of this relationship in terms of disease susceptibility, vaccine response, optimal health and productivity, and thus exogenous approaches to positively shape microbiome-immune system interactions.