Preventing subclinical necrotic enteritis through Lactobacillus johnsonii BS15 by ameliorating lipid metabolism and intestinal microflora in broiler chickens

Treatment of chickens with lactobacilli prior to challenge with Clostridium perfringens modifies innate responses and gut morphology

Necrotic enteritis caused by Clostridium perfringens (CP), is a common enteric disease of poultry that has been previously controlled by in-feed antibiotics. However, due to the rapid emergence of antimicrobial resistance, alternatives to antibiotics such as probiotics have received considerable attention because of their immunomodulatory and intestinal health benefits. The present study investigated the effects of probiotic lactobacilli on gut histomorphology and intestinal innate responses in chickens. Day-old male broiler chickens were treated with 1 × 107 or 1 × 108 colony-forming units (CFU) of a lactobacilli cocktail on days 1, 7, 14, and 20 post-hatch, while control groups were not treated with lactobacilli. On day 21, birds in all groups (except the negative control) were challenged with 3 × 108 CFU of CP for 3 days. Intestinal tissue samples were collected before and after the CP challenge to assess gene expression and for histomorphological analysis. Lactobacilli treatment at a dose of 1 × 108 CFU conferred partial protection against NE by lowering lesion scores, increasing villus height in the ileum and reducing crypt depth in the jejunum. In addition, 1 × 108 CFU of lactobacilli enhanced the expression of Toll-like receptor (TLR) 2, interferon-gamma (IFN-γ), interleukin (IL)-10, IL-12, and IL-13 in both the jejunum and ileum at different timepoints and subsequently decreased the expression of transforming growth factor beta (TGF-β) and IL-1β post-CP challenge. In conclusion, the results indicate that treatment with lactobacilli mitigated NE in a dose-dependent manner via improvement of intestinal morphology and modulation of innate immune response in chickens.

Bacillus subtilis HW2 enhances growth performance and alleviates gut injury via attenuation of endoplasmic reticulum stress and regulation of gut microbiota in broilers under necrotic enteritis challenge

This study investigated the effects of Bacillus subtilis HW2 on the growth performance, immune response, endoplasmic reticulum (ER) stress, and intestinal health in broilers with necrotic enteritis. Three hundred 1-day-old male Cobb 500 broilers (33.88 ± 2.34 g) were randomly allocated to 5 groups including non-infected control (NC group), basal diet + necrotic enteritis challenge (NE group), basal diet + 1 × 106 CFU/g B. subtilis HW2 + necrotic enteritis challenge (L-Pro group), basal diet + 5 × 106 CFU/g B. subtilis HW2 + necrotic enteritis challenge (M-Pro group), and basal diet + 1 × 107 CFU/g B. subtilis HW2 + necrotic enteritis challenge (H-Pro group), with 6 replicates per group. All broilers except NC group were orally given with sporulated coccidian oocysts at day 14 and Clostridium perfringens from days 19 to 21. Results showed that L-Pro and M-Pro groups improved growth performance and intestinal morphology in necrotic enteritis-challenged broilers, and L-Pro, M-Pro, and H-Pro groups improved intestinal barrier function and immune response and decreased ER stress in necrotic enteritis-challenged broilers. Analysis of the gut microbiota revealed that L-Pro group increased the abundances of Alistipes, Coprobacter, Barnesiella, and Limosilactobacillus, decreased Erysipelatoclostridium abundance on day 42 in necrotic enteritis-challenged broilers. M-Pro group increased Turicibacter abundance on day 28 and the abundances of Alistipes, Barnesiella, and Limosilactobacillus on day 42 in necrotic enteritis-challenged broilers. H-Pro group decreased Romboutsia abundance on day 28 and unidentified_Clostridia abundance on day 42 in necrotic enteritis-challenged broilers. Analysis of short-chain fatty acids (SCFAs) revealed higher isobutyric acid and isovaleric acid levels in L-Pro and M-Pro groups than NE group. Correlation analysis revealed the correlations between the biochemical parameters and gut microbiota as well as SCFAs, especially Romboutsia, Barnesiella, Coprobacter, isobutyric acid, and isovaleric acid. Overall, our results indicated that B. subtilis HW2 supplementation could ameliorate necrotic enteritis infection-induced gut injury. The optimal dietary supplementation dosage of Bacillus subtilis HW2 was 5 × 106 CFU/g.

Baicalin ameliorates the gut barrier function and intestinal microbiota of broiler chickens

The deoxynivalenol (DON)-contaminated feeds can impair chicken gut barrier function, disturb the balance of the intestinal microbiota, decrease chicken growth performance and cause major economic loss. With the aim of investigating the ameliorating effects of baicalin on broiler intestinal barrier damage and gut microbiota dysbiosis induced by DON, a total of 150 Arbor Acres broilers are used in the present study. The morphological damage to the duodenum, jejunum, and ileum caused by DON is reversed by treatment with different doses of baicalin, and the expression of tight junction proteins (ZO-1, claudin-1, and occludin) is also significantly increased in the baicalin-treated groups. Moreover, the disturbance of the intestinal microbiota caused by DON-contaminated feed is altered by baicalin treatment. In particular, compared with those in the DON group, the relative abundances of Lactobacillus, Lachnoclostridium, Ruminiclostridium and other beneficial microbes in the baicalin-treated groups are significantly greater. However, the percentage of unclassified_f__Lachnospiraceae in the baicalin-treated groups is significantly decreased in the DON group. Overall, the current results demonstrate that different doses of baicalin can improve broiler intestinal barrier function and the ameliorating effects on broiler intestinal barrier damage may be related to modulations of the intestinal microbiota.

Chlorogenic acid protects against intestinal inflammation and injury by inactivating the mtDNA-cGAS-STING signaling pathway in broilers under necrotic enteritis challenge

This study aimed to determine the effects of chlorogenic acid (CGA) on the growth performance, intestinal health, immune response, and mitochondrial DNA (mtDNA)-cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway in broilers under necrotic enteritis (NE) challenge. The 180 one-day-old male Cobb 500 broilers with similar body weight of 44.59 ± 1.39 g were randomly allocated into 3 groups. The groups were control diet (Control group), control diet + NE challenge (NE group), and control diet + 500 mg/kg CGA + NE challenge (NE + CGA group), with 6 replicates per treatment. All broilers except the Control group were given sporulated coccidian oocysts (d 14) and Clostridium perfringens (d 19-21) by oral gavage. Our findings showed that CGA improved the growth performance and intestinal morphology in broilers under NE challenge. CGA supplementation elevated the barrier function in broilers under NE challenge, which reflected in the decreased serum concentrations of D-lactate and diamine oxidase, and upregulated jejunal protein expression of occludin. CGA supplementation also improved the immune function, which reflected in the increased concentrations and gene expressions of anti-inflammatory factors, and decreased concentrations and gene expressions of proinflammatory factors. CGA supplementation further enhanced intestinal cell proliferation and differentiation, which manifested in the increased number of goblet cells and positive cells of proliferating cell nuclear antigen on d 28 and 42. Furthermore, CGA supplementation decreased the mtDNA (d 42) and mitochondrial reactive oxygen species levels (d 28 and 42), and increased the mitochondrial membrane potential (d 42) and mitochondrial complex I (d 28 and 42) or III (d 28) activity. Broilers challenged with NE had upregulated jejunal protein expressions of cGAS, phospho-TANK-binding kinase 1, and phospho-interferon regulatory factor 7 compared with the Control group, which were downregulated after CGA supplementation. In conclusion, dietary supplementation CGA could protect against intestinal inflammation and injury by reducing the leakage of mtDNA and inactivating the cGAS-STING signaling pathway in broilers under NE challenge.

Modulation of Broiler Intestinal Changes Induced by Clostridium perfringens and Deoxynivalenol through Probiotic, Paraprobiotic, and Postbiotic Supplementation

Deoxynivalenol (DON) is a predisposing factor for necrotic enteritis. This study aimed to investigate the effects of a DON and Clostridium perfringens (CP) challenge on the intestinal morphology, morphometry, oxidative stress, and immune response of broilers. Additionally, we evaluated the potential of a Lactobacillus spp. mixture as an approach to mitigate the damage induced by the challenge. One-day-old broiler chickens (n = 252) were divided into seven treatment groups: Control, DON, CP, CP + DON, VL (DON + CP + viable Lactobacillus spp. mixture), HIL (DON + CP + heat-inactivated Lactobacillus spp. mixture), and LCS (DON + CP + Lactobacillus spp. mixture culture supernatant). Macroscopic evaluation of the intestines revealed that the CP + DON group exhibited the highest lesion score, while the VL and HIL groups showed the lowest scores. Microscopically, all Lactobacillus spp. treatments mitigated the morphological changes induced by the challenge. DON increased levels of reactive oxygen species (ROS) in the jejunum, and CP increased ROS levels in the jejunum and ileum. Notably, the Lactobacillus spp. treatments did not improve the antioxidant defense against CP-induced oxidative stress. In summary, a Lactobacillus spp. mixture, whether used as a probiotic, paraprobiotic, or postbiotic, exerted a partially protective effect in mitigating most of the intestinal damage induced by DON and CP challenges.

The Effects of Lactobacillus johnsonii on Diseases and Its Potential Applications

Lactobacillus johnsonii has been used as a probiotic for decades to treat a wide range of illnesses, and has been found to have specific advantages in the treatment of a number of ailments. We reviewed the potential therapeutic effects and mechanisms of L. johnsonii in various diseases based on PubMed and the Web of Science databases. We obtained the information of 149 L. johnsonii from NCBI (as of 14 February 2023), and reviewed their comprehensive metadata, including information about the plasmids they contain. This review provides a basic characterization of different L. johnsonii and some of their potential therapeutic properties for various ailments. Although the mechanisms are not fully understood yet, it is hoped that they may provide some evidence for future studies. Furthermore, the antibiotic resistance of the various strains of L. johnsonii is not clear, and more complete and in-depth studies are needed. In summary, L. johnsonii presents significant research potential for the treatment or prevention of disease; however, more proof is required to justify its therapeutic application. An additional study on the antibiotic resistance genes it contains is also needed to reduce the antimicrobial resistance dissemination.

Recent Trends on Mitigative Effect of Probiotics on Oxidative-Stress-Induced Gut Dysfunction in Broilers under Necrotic Enteritis Challenge: A Review

Gut health includes normal intestinal physiology, complete intestinal epithelial barrier, efficient immune response, sustained inflammatory balance, healthy microbiota, high nutrient absorption efficiency, nutrient metabolism, and energy balance. One of the diseases that causes severe economic losses to farmers is necrotic enteritis, which occurs primarily in the gut and is associated with high mortality rate. Necrotic enteritis (NE) primarily damages the intestinal mucosa, thereby inducing intestinal inflammation and high immune response which diverts nutrients and energy needed for growth to response mediated effects. In the era of antibiotic ban, dietary interventions like microbial therapy (probiotics) to reduce inflammation, paracellular permeability, and promote gut homeostasis may be the best way to reduce broiler production losses. The current review highlights the severity effects of NE; intestinal inflammation, gut lesions, alteration of gut microbiota balance, cell apoptosis, reduced growth performance, and death. These negative effects are consequences of; disrupted intestinal barrier function and villi development, altered expression of tight junction proteins and protein structure, increased translocation of endotoxins and excessive stimulation of proinflammatory cytokines. We further explored the mechanisms by which probiotics mitigate NE challenge and restore the gut integrity of birds under disease stress; synthesis of metabolites and bacteriocins, competitive exclusion of pathogens, upregulation of tight junction proteins and adhesion molecules, increased secretion of intestinal secretory immunoglobulins and enzymes, reduction in pro-inflammatory cytokines and immune response and the increased production of anti-inflammatory cytokines and immune boost via the modulation of the TLR/NF-ĸ pathway. Furthermore, increased beneficial microbes in the gut microbiome improve nutrient utilization, host immunity, and energy metabolism. Probiotics along with biosecurity measures could mitigate the adverse effects of NE in broiler production.

Changyanning regulates gut microbiota and metabolism to ameliorate intestinal injury induced by ETEC K88

Enterotoxigenic Escherichia coli (ETEC) is a common pathogen of swine colibacillosis, which can causing a variety of diseases initiate serious economic losses to the animal husbandry industry. The traditional Chinese medicine Changyanning (CYN) often used for diarrhea caused by the accumulation of damp heat in the gastrointestinal tract, has anti-bacterial, anti-inflammatory and anti-oxidation effects. This study investigated the effect of CYN on gut microbiota and metabolism in mice infected with ETEC K88. A total of 60 Kunming mices were divided into Control group, ETEC K88 group, CYN.L group (2.5 g/kg), CYN.M group (5 g/kg), CYN.H group (10 g/kg) and BTW group (10 g/kg), determined clinical symptoms, intestinal morphology, inflammatory responses, gut microbiota as well as serum metabolites. CYN administration elevated ETEC K88-induced body weight loss, ameliorated duodenum, ilem, colon pathological injury, and reduced the increase of spleen index caused by ETEC. CYN also reduced the levels of pro-inflammatory cytokines (IL-6, TNE-α) in the serum. 16s rRNA gene sequencing results showed that CYN increased the abundance of beneficial bacteria Lactobacillus but decreased the abundance of pathogenic bacteria Escherichia in the feces of mice. Moreover, CYN participates in amino acid biosynthesis and metabolism in the process of serum metabolism to regulates ameliorate intestinal injury induced by ETEC K88. In conclusion, CYN regulates gut microbiota and metabolism to ameliorate intestinal injury induced by ETEC K88.

Lactobacillus (L. plantarum & L. rhamnosus) and Saccharomyces (S. cerevisiae): effects on performance, biochemical parameters, ammonium ion in manure, and digestibility of broiler chickens

Two strains of Lactobacillus combined with Baker's yeast (Saccharomyces cerevisiae) used as probiotics were evaluated to replace antibiotics in poultry flocks by reducing ammonia emissions in manure of broilers without comprising performance or health. One-day-old Cobb 500 broilers (600) were fed starter, grower, and finisher diets as control (CON); probiotic S. cerevisiae, inclusion rate at 4.26 × 10⁶ CFU/kg of feed (SCY); probiotic L. plantarum and L. rhamnosus, inclusion rate at 4.35 × 10⁸ CFU/kg of feed (LPR) for each; and a combination of Lactobacillus plantarum and L. rhamnosus at 4.35 × 10⁸ CFU/kg of feed for each plus Saccharomyces cerevisiae and 4.26 × 10⁶ CFU/kg of feed (SWL). The 4 treatments had 5 replicates (pens), each with 30 broilers. Performance was measured weekly as feed consumption, weight gain, BW, and feed conversion ratio (FCR) over a 6-wk grow-out period. Accompanying biochemical analyses included lipase activity of the pancreas, liver weight, and uric acid (UA) concentration in liver. Albumin, total protein, UA, ammonia, and blood urea nitrogen (BUN) were measured in serum. Ammonium (NH₄⁺) in manure and apparent ileal digestibility from digesta were also measured. Significance was determined at P ≤ 0.05. Results showed that biochemical analyses had no significant treatment effect; however, there were significant temporal changes in performance measures for individual treatments. Feed consumption increased over time for all treatments (P = 2.00 × 10^-16). CON had lower weight gain in wk 2 (P = 0.013) compared to all treatment and the lowest BW in wk 5 (P = 0.0008) and wk 6 (P = 0.0124) compared to SWL. Specific probiotic strains, with well-defined inclusion rates, and surrounding environmental analyses of present microbes are needed to ascertain effects of probiotics. Other important areas for investigation include 1) confirmation of probiotics present in the digesta/ceca and how they alter the microbiota within the gastrointestinal (GI) tract and 2) the serum heterophil:lymphocyte ratio to further examine potential immune responses to the probiotics.

Effects of Treatment with Lactobacilli on Necrotic Enteritis in Broiler Chickens

Growth promoter antibiotics have been commonly used for the control of necrotic enteritis (NE) in broilers for decades. However, due to a ban on the use of these antibiotics, alternatives such as probiotics have been tested widely for NE control. The present study tested the efficacy of four different species of lactobacilli (two isolates of Lactobacillus johnsonii and one of Ligilactobacillus (L.) salivarius, Limosilactobacillus (L.) reuteri, and L. crispatus) against NE. Day-old male broiler chickens were divided into six groups and orally inoculated with 1 × 10⁷ or 1 × 10⁸ colony-forming units (CFU) of lactobacilli on 1, 7, 14, and 20 days of age. While negative and positive control groups did not receive lactobacilli, the latter was challenged with Clostridium perfringens (CP). Chickens, at 21 days old, were challenged for 3 days with 3 × 10⁸ CFU of a virulent strain of CP. Tissues were collected for immune system gene expression, immunophenotyping, intestinal histomorphometry, and microbiota analysis. Lactobacilli inoculation conferred partial protection in chickens against NE, marked by lowered lesion scores and improved villus:crypt ratio. Immunomodulatory effects were demonstrated by the significant alteration of interferon (IFN)-γ, interleukin (IL)-1β, IL-2, IL-12p35, IL-17, and transforming growth factor beta (TGF-β) gene transcription in the duodenum and jejunum as well as subtle changes in the frequency of CD8 + T cells and B cells in the cecal tonsil of the treated chickens. Microbiota analysis showed increased levels of some bacterial phyla including Actinobacteria, Lactobacillaceae, and Firmicutes. In conclusion, these findings suggest that the use of certain lactobacilli can reduce NE severity and modulate immune responses and intestinal microbiota composition in chickens.

Microbiota Transplantation in Day-Old Broiler Chickens Ameliorates Necrotic Enteritis via Modulation of the Intestinal Microbiota and Host Immune Responses

A microbiota transplant (MT) originating from mature adult chicken ceca and propagated in bioreactors was administered to day-old broiler chicks to ascertain the degree to which, and how, the MT affects Clostridium perfringens (Cp)-incited necrotic enteritis (NE). Using a stress predisposition model of NE, birds administered the MT and challenged with Cp showed fewer necrotic lesions, and exhibited a substantially higher α- and β-diversity of bacteria in their jejunum and ceca. Birds challenged with Cp and not administered the MT showed decreased Lactobacillus and increased Clostridium sensu strico 1 in the jejunum. In ceca, Megamonas, a genus containing butyrate-producing bacteria, was only present in birds administered the MT, and densities of this genus were increased in birds challenged with Cp. Metabolite profiles in cecal digesta were altered in birds administered the MT and challenged with the pathogen; 59 metabolites were differentially abundant following MT treatment, and the relative levels of short chain fatty acids, butyrate, valerate, and propionate, were decreased in birds with NE. Birds administered the MT and challenged with Cp showed evidence of enhanced restoration of intestinal barrier functions, including elevated mRNA of MUC2B, MUC13, and TJP1. Likewise, birds administered the MT exhibited higher mRNA of IL2, IL17A, and IL22 at 2-days post-inoculation with Cp, indicating that these birds were better immunologically equipped to respond to pathogen challenge. Collectively, study findings demonstrated that administering a MT containing a diverse mixture of microorganisms to day-old birds ameliorated NE in broilers by increasing bacterial diversity and promoting positive immune responses.

Probiotics as Alternatives to Antibiotics for the Prevention and Control of Necrotic Enteritis in Chickens

Necrotic enteritis (NE) in poultry is an economically important disease caused by Clostridium perfringens type A bacteria. A global trend on restricting the use of antibiotics as feed supplements in food animal production has caused a spike in the NE incidences in chickens, particularly in broiler populations. Amongst several non-antibiotic strategies for NE control tried so far, probiotics seem to offer promising avenues. The current review focuses on studies that have evaluated probiotic effects on C. perfringens growth and NE development. Several probiotic species, including Lactobacillus, Enterococcus, Bacillus, and Bacteroides bacteria as well as some yeast species have been tested in chickens against C. perfringens and NE development. These findings have shown to improve bird performance, reduce C. perfringens colonization and NE-associated pathology. The underlying probiotic mechanisms of NE control suggest that probiotics can help maintain a healthy gut microbial balance by modifying its composition, improve mucosal integrity by upregulating expression of tight-junction proteins, and modulate immune responses by downregulating expression of inflammatory cytokines. Collectively, these studies indicate that probiotics can offer a promising platform for NE control and that more investigations are needed to study whether these experimental probiotics can effectively prevent NE in commercial poultry operational settings.

Whole genome sequencing for the risk assessment of probiotic lactic acid bacteria

Probiotic bacteria exhibit beneficial effects on human and/or animal health, and have been widely used in foods and fermented products for decades. Most probiotics consist of lactic acid bacteria (LAB), which are used in the production of various food products but have also been shown to have the ability to prevent certain diseases. With the expansion of applications for probiotic LAB, there is an increasing concern with regard to safety, as cases with adverse effects, i.e., severe infections, transfer of antimicrobial resistance genes, etc., can occur. Currently, in vitro assays remain the primary way to assess the properties of LAB. However, such methodologies are not meeting the needs of strain risk assessment on a high-throughput scale, in the context of the evolving concept of food safety. Analyzing the complete genetic information, including potential virulence genes and other determinants with a negative impact on health, allows for assessing the safe use of the product, for which whole-genome sequencing (WGS) of individual LAB strains can be employed. Genomic data can also be used to understand subtle differences in the strain level important for beneficial effects, or protect patents. Here, we propose that WGS-based bioinformatics analyses are an ideal and cost-effective approach for the initial in silico microbial risk evaluation, while the technique may also increase our understanding of LAB strains for food safety and probiotic property evaluation.

Intestinal Mucosal Immunity-Mediated Modulation of the Gut Microbiome by Oral Delivery of Enterococcus faecium Against Salmonella Enteritidis Pathogenesis in a Laying Hen Model

Enterococcus faecium (E. faecium) is a protective role that has crucial beneficial functions on intestinal homeostasis. This study aimed to investigate the effects of E. faecium on the laying performance, egg quality, host metabolism, intestinal mucosal immunity, and gut microbiota of laying hens under the Salmonella Enteritidis (S. Enteritidis) challenge. A total of 400 45-week-old laying hens were randomly divided into four treatments (CON, EF, SCON, and SEF groups) with five replicates for each group and 20 hens per replicate and fed with a basal diet or a basal diet supplemented with E. faecium (2.5 × 10⁸ cfu/g feed). The experiment comprised two phases, consisting of the pre-salmonella challenged phase (from day 14 to day 21) and the post-salmonella challenged phase (from day 21 to day 42). At day 21 and day 22, the hens in SCON and SEF groups were orally challenged with 1.0 ml suspension of 10⁹ cfu/ml S. Enteritidis (CVCC3377) daily, whereas the hens in CON and EF groups received the same volume of sterile PBS. Herein, our results showed that E. faecium administration significantly improved egg production and shell thickness during salmonella infection. Also, E. faecium affected host lipid metabolism parameters via downregulating the concentration of serum triglycerides, inhibited oxidative stress, and enhanced immune functions by downregulating the level of serum malondialdehyde and upregulating the level of serum immunoglobulin G. Of note, E. faecium supplementation dramatically alleviated intestinal villi structure injury and crypt atrophy, and improved intestinal mucosal barrier injuries caused by S. Enteritidis challenge. Moreover, our data revealed that E. faecium supplementation ameliorated S. Enteritidis infection-induced gut microbial dysbiosis by altering the gut microbial composition (reducing Bacteroides, Desulfovibrio, Synergistes, and Sutterella, and increasing Barnesiella, Butyricimonas, Bilophila, and Candidatus_Soleaferrea), and modulating the gut microbial function, such as cysteine and methionine metabolism, pyruvate metabolism, fatty acid metabolism, tryptophan metabolism, salmonella infection, and the PI3K-Akt signaling pathway. Taken together, E. faecium has a strong capacity to inhibit the S. Enteritidis colonization of hens. The results highlight the potential of E. faecium supplementation as a dietary supplement to combat S. Enteritidis infection in animal production and to promote food safety.

The Role of Nutraceuticals and Phytonutrients in Chickens’ Gastrointestinal Diseases

Simple Summary

The use of nutraceuticals and phytonutrients in poultry nutrition has been extensively explored over the past decade. The interest in these substances is linked to the search for natural compounds that can be effectively used to prevent and treat some of the main diseases of the chicken. The serious problem of antibiotic resistance and the consequent legislative constraints on their use required the search for alternatives. The purpose of this review is to describe the current status of the effects of some substances, such as probiotics and prebiotics, organic acids, vitamins and phytogenic feed additives, focusing specifically on studies concerning the prevention and treatment of four main gastrointestinal diseases in chicken: salmonellosis, necrotic enteritis (caused by Clostridium perfringens), campylobacteriosis, and coccidiosis. A brief description of these diseases and the effects of the main bioactive principles of the nutraceutical or phytonutrient groups will be provided. Although there are conflicting results, some works show very promising effects, with a reduction in the bacterial or protozoan load following treatment. Further studies are needed to verify the real effectiveness of these compounds and make them applicable in the field.

Abstract

In poultry, severe gastrointestinal diseases are caused by bacteria and coccidia, with important economic losses in the poultry industry and requirement of treatments which, for years, were based on the use of antibiotics and chemotherapies. Furthermore, Salmonella spp., Clostridium perfringens, and Campylobacter jejuni can cause serious foodborne diseases in people, resulting from consumption of poultry meat, eggs, and derived products. With the spread of antibiotic resistance, which affects both animals and humans, the restriction of antibiotic use in livestock production and the identification of a list of “critically important antimicrobials” became necessary. For this reason, researchers focused on natural compounds and effective alternatives to prevent gastrointestinal disease in poultry. This review summarizes the results of several studies published in the last decade, describing the use of different nutraceutical or phytonutrients in poultry industry. The results of the use of these products are not always encouraging. While some of the alternatives have proven to be very promising, further studies will be needed to verify the efficacy and practical applicability of other compounds.

Necrotic enteritis in chickens: a review of pathogenesis, immune responses and prevention, focusing on probiotics and vaccination

Necrotic enteritis (NE), caused by Clostridium perfringens (CP), is one of the most common of poultry diseases, causing huge economic losses to the poultry industry. This review provides an overview of the pathogenesis of NE in chickens and of the interaction of CP with the host immune system. The roles of management, nutrition, probiotics, and vaccination in reducing the incidence and severity of NE in poultry flocks are also discussed.

Compound Probiotics Improve Body Growth Performance by Enhancing Intestinal Development of Broilers with Subclinical Necrotic Enteritis

The aim of this study is to explore whether or not the combined application of BS15 and H2 is capable to have a more effective control effect on SNE in broilers. A total of 240 1-day-old female chickens were randomly divided into 5 groups: (a) basal diet in negative control group (NC group); (b) basal diet + SNE infection (coccidiosis vaccine + CP) (PC group); (c) basal diet + SNE infection + H2 pre-treatment (BT group); (d) basal diet + SNE infection + BS15 pre-treatment (LT group); and (e) basal diet + SNE infection + H2 pre-treatment + BS15 pre-treatment (MT group). The results showed the MT group had the most positive effect on inhibiting the negative effect of growth performance at 42 days of age. In the detection of the NC, PC, and MT group indicators at 28 days of age, we found that MT group significantly promoted ileum tissue development of broilers, and the ileum of broilers in the MT group formed a flora structure different from NC and PC, although it was found that the MT group had no effect on the butyrate level in the cecum, but it could affect the serum immune level, such as significantly reducing the level of pro-inflammatory cytokine IL-8 and increasing the content of immunoglobulin IgM and IgG. In conclusion, the composite preparation of Lactobacillus johnsonii BS15 and Bacillus licheniformis H2 could effectively improve the growth performance against SNE broilers, which is possibly caused by the improvement of the immune levels, the reduction of inflammation levels, and the promotion of the intestinal development.

Probiotic Lactobacillus johnsonii BS15 Prevents Memory Dysfunction Induced by Chronic High-Fluorine Intake through Modulating Intestinal Environment and Improving Gut Development

In recent years, the influence of chronic fluorosis on the brain has been widely reported. Our study aimed to demonstrate the potential mechanism underlying the impairment of memory function by excessive fluorine intake. We also evaluated whether improvement of intestinal microflora could be a potential therapy to prevent the negative influences from the perspective of gut-brain axis. Male ICR mice were randomly divided into three groups and administered with either phosphate buffered saline (PBS) (Control and F groups) or Lactobacillus johnsonii BS15 (FP group; daily amounts of 1 × 10⁹ CFU/mL), a probiotic strain, by oral gavage throughout a 98-day experimental period. Sodium fluoride (100 mg/L) was added to the drinking water of the F and FP groups. Animals were sacrificed for sampling with or without water avoidance stress (WAS) at two phases of the experiment and behavioral tests including T-maze test and passive avoidance test were also performed. Based on the results of behavioral tests, probiotic reversed the fluorine-induced memory dysfunction. In addition, L. johnsonii BS15 also increased the antioxidant capacities (serum and hippocampal tissue) and hippocampal synaptic plasticity-related mRNA expression after excessive fluoride ingestion. Moreover, the increased colonization of L. johnsonii BS15 also protected the small intestines from the damages of growth performance, visceral indexes, intestinal development, digestive, and secretory functions by changing the structure of the microflora and then improving intestinal permeability and integrity. L. johnsonii BS15 also improved the ability of flourosis mice against psychological stress indicated by the changes in behavioral tasks, hippocampal antioxidant levels, and synaptic plasticity-related mRNA expressions. Lactobacillus johnsonii BS15 intake appears as a promising way to ameliorate fluorine-induced memory dysfunction, especially under psychological stress.

Probiotic Lactobacillus johnsonii BS15 Promotes Growth Performance, Intestinal Immunity, and Gut Microbiota in Piglets

Numerous studies have investigated the beneficial effects of Lactobacillus johnsonii strain BS15 on mice and broilers. This study aimed to understand the growth-promoting effects of BS15 on piglets. We determined the effects of L. johnsonii BS15 and a commercial probiotic strain, Bacillus subtilis JS01. Seventy-two suckling piglets (1 ± 2-day-old) were divided into three groups and fed with diets supplemented with 1 × 10⁶ colony-forming units (cfu) BS15 per gram of feed (BS15 group); 1 × 10⁶ cfu JS01 per gram of feed (JS01 group); or de Man, Rogosa, and Sharpe liquid medium (control group) 35 days. Compared with JS01, BS15 significantly improved the daily weight gain and diarrhea index of the piglets. The BS15 group had higher fecal sIgA levels, whereas the JS01 group had high fecal sIgA levels only after 35 days of treatment. Additionally, BS15 altered T cell subsets in peripheral blood by significantly increasing the CD3⁺CD4⁺ T cell percentage and CD3⁺CD4⁺/CD3⁺CD8⁺ ratio and decreasing the CD3⁺CD8⁺ T cell percentage. Moreover, BS15 exerted better beneficial effects on fecal microbiota than JS01. Specifically, the BS15 group had markedly increased Clostridium, Peptococcus, and Lactobacillus populations on days 7 and 21 of treatment and reduced Escherichia coli populations on day 35 of treatment. These findings indicated that BS15 can be applied as a probiotic that promotes growth performance and controls diarrhea in piglets.

Protective Effects of Lactobacillus plantarum 16 and Paenibacillus polymyxa 10 Against Clostridium perfringens Infection in Broilers

This study aimed to investigate the protective effects of Lactobacillus plantarum 16 (Lac16) and Paenibacillus polymyxa 10 (BSC10) against Clostridium perfringens (Cp) infection in broilers. A total of 720 one-day-old chicks were randomly divided into four groups. The control and Cp group were only fed a basal diet, while the two treatment groups received basal diets supplemented with Lac16 (1 × 10⁸ cfu·kg^-1) and BSC10 (1 × 10⁸ cfu·kg^-1) for 21 days, respectively. On day 1 and days 14 to 20, birds except those in the control group were challenged with 1 × 10⁸ cfu C. perfringens type A strain once a day. The results showed that both Lac16 and BSC10 could ameliorate intestinal structure damage caused by C. perfringens infection. C. perfringens infection induced apoptosis by increasing the expression of Bax and p53 and decreasing Bcl-2 expression and inflammation evidence by higher levels of IFN-γ, IL-6, IL-1β, iNOS, and IL-10 in the ileum mucosa, and NO production in jejunal mucosa, which was reversed by Lac16 and BSC10 treatment except for IL-1β (P < 0.05). Besides, the two probiotics restored the intestinal microbiota imbalance induced by C. perfringens infection, characterized by the reduced Firmicutes and Proteobacteria and the increased Bacteroidetes at the phyla level and decreased Bacteroides fragilis and Gallibacterium anatis at the genus level. The two probiotics also reversed metabolic pathways of the microbiota in C. perfringens-infected broilers, including B-vitamin biosynthesis, peptidoglycan biosynthesis, and pyruvate fermentation to acetate and lactate II pathway. In conclusion, Lac16 and BSC10 can effectively protect broilers against C. perfringens infection through improved composition and metabolic pathways of the intestinal microbiota, intestinal structure, inflammation, and anti-apoptosis.

Necrotic enteritis challenge regulates peroxisome proliferator-1 activated receptors signaling and β-oxidation pathways in broiler chickens

Necrotic enteritis (NE) is an important enteric disease in poultry and has become a major concern in poultry production in the post-antibiotic era. The infection with NE can damage the intestinal mucosa of the birds leading to impaired health and, thus, productivity. To gain a better understanding of how NE impacts the gut function of infected broilers, global mRNA sequencing (RNA-seq) was performed in the jejunum tissue of NE challenged and non-challenged broilers to identify the pathways and genes affected by this disease. Briefly, to induce NE, birds in the challenge group were inoculated with 1 mL of Eimeria species on day 9 followed by 1 mL of approximately 10⁸ CFU/mL of a NetB producing Clostridium perfringens on days 14 and 15. On day 16, 2 birds in each treatment were randomly selected and euthanized and the whole intestinal tract was evaluated for lesion scores. Duodenum tissue samples from one of the euthanized birds of each replicate (n = 4) was used for histology, and the jejunum tissue for RNA extraction. RNA-seq analysis was performed with an Illumina RNA HiSeq 2000 sequencer. The differentially expressed genes (DEG) were identified and functional analysis was performed in DAVID to find protein–protein interactions (PPI). At a false discovery rate threshold <0.05, a total of 377 DEG (207 upregulated and 170 downregulated) DEG were identified. Pathway enrichment analysis revealed that DEG were considerably enriched in peroxisome proliferator-activated receptors (PPAR) signaling (P < 0.01) and β-oxidation pathways (P < 0.05). The DEG were mostly related to fatty acid metabolism and degradation (cluster of differentiation 36 [CD36], acyl-CoA synthetase bubblegum family member-1 [ACSBG1], fatty acid-binding protein-1 and -2 [FABP1] and [FABP2]; and acyl-coenzyme A synthetase-1 [ACSL1]), bile acid production and transportation (acyl-CoA oxidase-2 [ACOX2], apical sodium–bile acid transporter [ASBT]) and essential genes in the immune system (interferon-, [IFN-γ], LCK proto-oncogene, Src family tyrosine kinase [LCK], zeta chain of T cell receptor associated protein kinase 70 kDa [ZAP70], and aconitate decarboxylase 1 [ACOD1]). Our data revealed that pathways related to fatty acid digestion were significantly compromised which thereby could have affected metabolic and immune responses in NE infected birds.

Lactobacillus plantarum BSGP201683 Improves the Intestinal Barrier of Giant Panda Microbiota-Associated Mouse Infected by Enterotoxigenic Escherichia coli K88

Giant pandas often suffered from gastrointestinal disease, especially the captive sub-adult one. Our study aims to investigate whether L. plantarum G83, a good panda-derived probiotic, can improve the intestinal barrier against the enterotoxigenic Escherichia coli K88 (E. coli K88) infection in giant panda microbiota-associated mice (GPAM). We treated SPF mice with antibiotics cocktail and transplanted the giant panda intestinal microbiota to set up a GPAM. Our results demonstrated that the microbiota of GPAM changed over time and was relatively stable in the short-term experiment (2-4 weeks). Whereafter, the GPAM pretreated with L. plantarum G83 for 15 days and infected with enterotoxigenic E. coli K88. The result indicated that the number of Bifidobacteria spp. increased in GPAM-G and GPAM-GE groups; the Lactobacillus spp. only increased in the GPAM-G group. Although the abundance of Enterobacteriaceae spp. only decreased in the GPAM-G group, the copy number of Escherichia coli in the GPAM-E group was significantly lower than that in the other groups. Meanwhile, the L. plantarum G83-induced alteration of microbiota could increase the mRNA expression of Claudin-1, Zo-1, and Occludin-1 in the GPAM-G group in the ileum; only Occludin-1 was increased in the GPAM-GE group. The sIgA in the ileum showed a positive response, also the result of body weight and histology in both the GPAM-G and GPAM-GE group. These results indicated that the L. plantarum G83 could improve the intestinal barrier to defense the enterotoxigenic E. coli K88 invasion.

Modulation of the intestinal microbiota of broilers supplemented with monensin or functional oils in response to challenge by Eimeria spp

The objective of this study was to evaluate the effect of supplementation with 100ppm sodium monensin or 0.15% of a blend of functional oils (cashew nut oil + castor oil) on the intestinal microbiota of broilers challenged with three different Eimeria spp. The challenge was accomplished by inoculating broiler chicks with sporulated oocysts of Eimeria tenella, Eimeria acervulina, and Eimeria maxima via oral gavage. A total of 864, day-old male broiler chicks (Cobb) were randomly assigned to six treatments (eight pens/treatment; 18 broilers/pen) in a 3 × 2 factorial arrangement, composed of three additives (control, monensin or blend), with or without Eimeria challenge. Intestinal contents was collected at 28 days of age for microbiota analysis by sequencing 16s rRNA in V3 and V4 regions using the Illumina MiSeq platform. Taxonomy was assigned through the SILVA database version 132, using the QIIME 2 software version 2019.1. No treatment effects (p > 0.05) were observed in the microbial richness at the family level estimated by Chao1 and the biodiversity assessed by Simpson’s index, except for Shannon's index (p < 0.05). The intestinal microbiota was dominated by members of the order Clostridiales and Lactobacillales, followed by the families Ruminococcaceae, Bacteroidaceae, and Lactobacillaceae, regardless of treatment. When the controls were compared, in the challenged control group there was an increase in Erysipelotrichaceae, Lactobacillaceae, Bacteroidaceae, Streptococcaceae, and Peptostreptococcaceae, and a decrease in Ruminococcaceae. Similar results were found for a challenged group that received monensin, while the blend partially mitigated this variation. Therefore, the blend alleviated the impact of coccidiosis challenge on the microbiome of broilers compared to monensin.

Quantifying Human Health Risks from Virginiamycin Use in Food Animals in China

Virginiamycin (VM), a streptogramin antibiotic, has been used to promote healthy growth and treat illnesses in farm animals in the United States and other countries. The combination streptogramin Quinupristin-Dalfopristin (QD) was approved in the United States in 1999 for treating patients with vancomycin-resistant Enterococcus faecium (VREF) infections. Many chickens and swine test positive for QD-resistant E. faecium, raising concerns that using VM in food animals might select for streptogramin-resistant strains of E. faecium that could compromise QD effectiveness in treating human VREF infections. Such concerns have prompted bans and phase-outs of VM as growth promoters in the United States and Europe. This study quantitatively estimates potential human health risks from QD-resistant VREF infections due to VM use in food animals in China. Plausible conservative (risk-maximizing) quantitative risk estimates are derived for future uses, assuming 100% resistance to linezolid and daptomycin and 100% prescription rate of QD to high-level (VanA) VREF-infected patients. Up to one shortened life every few decades to every few thousand years might occur in China from VM use in animals, although the most likely risk is zero (e.g., if resistance is not transferred from bacteria in food animals to bacteria infecting human patients). Sensitivity and probabilistic uncertainty analyses suggest that this conclusion is robust to several data gaps and uncertainties. Potential future human health risks from VM use in animals in China appear to be small or zero, even if QD is eventually approved for use in human patients.

Effects of dietary inulin supplementation on the composition and dynamics of cecal microbiota and growth-related parameters in broiler chickens

Inulin, a prebiotic, is an attractive alternative to antibiotic growth promoters in chickens. Dietary supplementation with inulin can improve growth performance, carcass yield, immune system activity, and serum biochemical parameters in chickens. A few studies investigated the impact of dietary inulin supplementation on chicken intestinal microbiota. In this study, we investigated how and why dietary supplementation with 1, 2, and 4% inulin can affect body weight gain, feed intake, food conversion rate, immunological parameters, serum biochemical parameters, and composition and dynamics of the cecal microbiota of Tegel broiler chickens using quantitative fluorescence in situ hybridization (qFISH). We showed that inulin inclusion has a negative effect on growth performance parameters before day 21 and a positive effect subsequently up to day 42. Quantitative FISH data revealed an age-dependent change in the cecal microbiota in the control broilers fed no inulin. Thus, relative abundances of Firmicutes and Actinobacteria decreased from 52.8 to 48.3% of total cells and from 8.7 to 1.4% at days 7 and 42, respectively. However, relative abundances of Bacteroidetes and Proteobacteria gradually increased from 9.3 to 26.9% of the total cells and from 10.7 to 21.1%, respectively, over the same periods. Inulin inclusion appeared to lower the relative abundances of Lactobacillus johnsonii and Bifidobacterium species at an early bird age, but it subsequently significantly (P < 0.05) increased their relative abundances. Such increases positively correlated with body weight gain of the birds, determined after day 21. Thus, dietary supplementation with inulin together with the addition of L. johnsonii and Bifidobacterium (B. gallinarum and B. pullorum) cultures at an early age may help overcome its early negative influence on growth performance. We believe that these findings can improve our knowledge on how inulin can change the intestinal microbiota of broiler chickens and help in developing an inulin feeding regime to optimize its beneficial role in chicken development.

Two different Clostridium perfringens strains produce different levels of necrotic enteritis in broiler chickens

Subclinical necrotic enteritis (NE) is primarily caused by the gram-positive bacterium, Clostridium perfringens (Cp). The trend towards removal of in-feed antimicrobials and subsequent increased emergence of infection in poultry has resulted in a wide interest in better understanding of the mechanism behind this disease. The virulence of NE, to a large extent, depends on the virulence of Cp strains. Thus, this study was to assess how 2 different strains of Cp affect performance and gut characteristics of broiler chickens. Ross 308 male broilers (n = 468) were assigned to a 2 × 3 factorial arrangement of treatments with antibiotics (Salinomycin at 72 ppm and zinc bacitracin at 50 ppm -, or +) and challenge (non-challenge, Cp EHE-NE18, or Cp WER-NE36). Oral administration of Eimeria oocysts (day 9) followed by inoculation with 1 mL 108 CFU Cp strains (day 14 and 15) were used to induce NE. Broiler performance was analyzed at day 10, 24, and 35. On day 16, intestinal lesion score and intestinal pH were evaluated and samples of cecal content were analyzed for bacterial counts and short-chain fatty acid concentrations (SCFA). Birds in both challenged groups showed higher feed conversion ratio (FCR), lower weight gain (P < 0.001), increased lesion scores in the jejunum (P < 0.01), and reduced pH in the ileum and cecum (P < 0.01), compared to the non-challenged birds. They also showed decreased numbers of Bacillus spp. (P < 0.001), and Ruminococcus spp. (P < 0.01) in the cecal content. On day 35, the NE36 challenged birds had a lower weight gain (P < 0.001) and higher FCR (P < 0.001) compared to the NE18 challenged birds. Interestingly, cecal Lactobacillus and lactate were increased by the NE challenge (P < 0.001), and to a greater extent in birds challenged with NE36 compared to the NE18 strain (P < 0.001). This study suggests that Cp strains varying in virulence produce different levels of disease in broiler chickens through modulating the gut environment, intestinal microbiota, and SCFA profile to different extents.

Probiotics mitigating subclinical necrotic enteritis (SNE) as potential alternatives to antibiotics in poultry

Subclinical necrotic enteritis (SNE) caused by Clostridium perfringens (CP), is an important disease in chickens, which causes huge economic losses by damaging the intestinal mucosa, decreasing digestion and absorption of nutrients. Use of antibiotics at a sub-therapeutic level as antimicrobial growth promoters in poultry feed prevents the birds from SNE and improves growth. Due to the ban on the use of antibiotics in 2006 as antimicrobial growth promoters have led to the reemergence of the disease. Worldwide numerous studies have been carried out to investigate the alternatives to antibiotics for the prevention of SNE. Possible alternatives to control SNE include probiotics, prebiotics, bacteriophages, essential oils, organic acids, secondary metabolites and other microbial products. Currently, probiotics are most extensively used in poultry production as an alternative to antibiotics. This review summarizes recent insights and experimental evidence on the use of different microorganisms like Bacillus, Lactic acid bacteria, Bifidobacteria, Enterococcus, yeast, etc. as valuable probiotics for prevention of SNE and potential molecular mechanisms responsible for ameliorating effects of probiotics against SNE.

Isolation and Preliminary Screening of a Weissella confusa Strain from Giant Panda (Ailuropoda melanoleuca)

Weissella confusa has recently received attention for its probiotic potential. Some W. confusa and Weissella cibaria strains isolated from fermented foods show favorable probiotic effects. However, the probiotic properties of W. confusa isolated from giant panda remain unreported to date. Thus, this study isolated a W. confusa strain from giant panda feces and then investigated its characteristics and probiotic properties. A lactic acid bacteria strain was isolated from giant panda fecal samples. The isolated strain was screened by in vitro probiotic property tests, including in vitro antimicrobial test, antioxidant test, surface hydrophobicity, and stress resistance. On the basis of biochemical identification and 16S rDNA sequencing, the W. confusa strain was identified as BSP201703. This Weissella confusa strain can survive at pH 2 and 0.3% (w/v) concentration of bile salt environment and inhibit common intestinal pathogens. It also possesses an in vitro antioxidant capacity, a high auto-aggregation ability, and a high surface hydrophobicity. BSP201703 might serve as a probiotic to giant pandas.

Galacto-Oligosaccharides Modulate the Juvenile Gut Microbiome and Innate Immunity To Improve Broiler Chicken Performance

Improvements in growth performance and health are key goals in broiler chicken production. Inclusion of prebiotic galacto-oligosaccharides (GOS) in broiler feed enhanced the growth rate and feed conversion of chickens relative to those obtained with a calorie-matched control diet. Comparison of the cecal microbiota identified key differences in abundances of Lactobacillus spp. Increased levels of Lactobacillus johnsonii in GOS-fed juvenile birds at the expense of Lactobacillus crispatus were linked to improved performance (growth rate and market weight). Investigation of the innate immune responses highlighted increases of ileal and cecal interleukin-17A (IL-17A) gene expression counterposed to a decrease in IL-10. Quantification of the autochthonous Lactobacillus spp. revealed a correlation between bird performance and L. johnsonii abundance. Shifts in the cecal populations of key Lactobacillus spp. of juvenile birds primed intestinal innate immunity without harmful pathogen challenge.IMPORTANCE Improvements in the growth rate of broiler chickens can be achieved through dietary manipulation of the naturally occurring bacterial populations while mitigating the withdrawal of antibiotic growth promoters. Prebiotic galacto-oligosaccharides (GOS) are manufactured as a by-product of dairy cheese production and can be incorporated into the diets of juvenile chickens to improve their health and performance. This study investigated the key mechanisms behind this progression and pinpointed L. johnsonii as a key species that facilitates the enhancements in growth rate and gut health. The study identified the relationships between the GOS diet, L. johnsonii intestinal populations, and cytokine immune effectors to improve growth.

Bacillus amyloliquefaciens CECT 5940 alone or in combination with antibiotic growth promoters improves performance in broilers under enteric pathogen challenge

A study was conducted to investigate the effects of Bacillus amyloliquefaciens CECT 5940 as a direct-fed microbial (DFM) alone or in association with bacitracin methylene disalicylate (BMD) in broilers under enteric pathogen challenge. A total of 1,530-day-old male Cobb500 chicks were randomly assigned to 5 treatments, with 9 replicate pens with 34 birds each. Treatments included positive control (PC, basal diet without additives or challenge); negative control (NC, basal diet without additive and challenged birds); NC + 0.05 g/kg BMD; NC + 1 g/kg DFM (10⁶ CFU B. amyloliquefaciens CECT 5940/g of feed); and NC + 0.05 g/kg BMD + 1 g/kg DFM. The challenge consisted of oral gavage with Eimeria maxima and Clostridium perfringens inoculum. Body weight gain (BWG), feed intake (FI), and feed conversion ratio (FCR) were evaluated on days 21, 35, and 42. Ileal and cecal content were collected on days 21 and 28 for C. perfringens enumeration by real-time PCR assay and the intestinal health was evaluated by scores. Uniformity (UN), carcass (CY), and breast meat yields (BMY) were evaluated on day 42. After 14 and 21 d post-inoculation, birds in the challenged groups had significant lower FI and BWG compared to the PC group (P < 0.05). However, the groups receiving DFM, BMD, or its combination presented better FCR, CY, BMY, UN, and lower incidence of footpad lesion and litter quality visual scores, compared to the NC group without feed additives (P < 0.05). Mortality was not affected by treatments (P > 0.05). Broilers fed DFM, BMD, or its combination presented lower C. perfringens in ileal content at 21 and 28 d compared to NC group without additives (P < 0.05) and also maintained gut health by keeping the frequency of ballooning, abnormal content, and swollen mucosa comparable to the PC group (P > 0.05). The study indicates that Bacillus amyloliquefaciens CECT 5940 is effective as BMD to provide similar performance and gut health in challenged broilers.

The impact of Bacillus subtilis DSM 32315 on the pathology, performance, and intestinal microbiome of broiler chickens in a necrotic enteritis challenge

It was hypothesized that dietary inclusion of Bacillus subtilis DSM 32315 could inhibit Clostridium perfringens induced necrotic enteritis (NE), thereby improving broiler performance. Male, d 0 chicks were randomly assigned 14 birds/pen, 11 pens/treatment in 3 treatments: a basal diet (control), a coccidiostat fed control (Narasin), and a direct fed microbial (DFM) B. subtilis DSM 32315 treatment. Necrotic enteritis was induced in all birds by oral inoculation of Eimeria maxima oocysts on d 12 and a virulent C. perfringens on d 16. Mortality was reduced (P < 0.001) in DFM and Narasin compared to control. DFM reduced (P < 0.001) feed conversion ratio (FCR) compared to control. Furthermore, DFM and Narasin reduced (P < 0.001) footpad lesions. The DFM was shown to increase (P < 0.05) Bacillus spp. and decrease (P < 0.05) C. perfringens in the ileum and cecum at several time points. To investigate microbiome changes in the cecum, digesta samples were analyzed with % guanine and cytosine (%G+C) microbial profiling which fractionates bacterial chromosomes based on the %G+C in DNA. The method revealed treatment profile peaks in low (27.0 to 34.5%), mid (40.5 to 54.0%), and high (59.0 to 68.0%) G+C fractions. 16S rRNA gene amplification and high throughput sequencing was conducted on each of these fractions in order to elucidate specific bacterial population differences. In the low and mid %G+C fractions, DFM had greater abundance of Lactobacillaceae family members (P = 0.03 and P = 0.01, respectively) and Lactobacillus salivarius (P = 0.04 and P = 0.01, respectively) than control or Narasin. Lactobacillus johnsonii was also greater in the low %G+C fraction compared to control and Narasin (P = 0.01). Lachnospiraceae (P = 0.04) and Ruminococcaceae (P < 0.01) in the mid %G+C fraction were reduced in the DFM compared to control. Positive alterations to the microbial populations in the gut of broilers may at least be a partial mechanism by which B. subtilis DSM 32315 reduced pathology and improved performance of broilers in the NE challenge.

Effect of a Synbiotic Mix on Intestinal Structural Changes, and Salmonella Typhimurium and Clostridium Perfringens Colonization in Broiler Chickens

Synbiotics can prevent gastrointestinal infections in broilers. This work studies the effect of a Synbiotic on broilers. One-day-old male broilers were divided into groups: Control; Synbiotic; Synbiotic + S. Typhimurium; Synbiotic + C. perfringens; Synbiotic + S. Typhimurium + C. perfringens; S. Typhimurium; C. perfringens; and S. Typhimurium + C. perfringens. Histopathological analysis revealed that the Synbiotic promoted longer villi, less deep crypts, and better villi-crypt ratio. Broilers treated with the Synbiotic, infected with pathogens or not, had healthier mucosa. In groups infected with pathogens, the frequency and intensity of histopathologic lesions were lessened often in groups treated with the Synbiotic. The Synbiotic group had higher lactic acid bacteria counts than the Control group on day 39, and the isolation frequency of S. Typhimurium was lower (p < 0.05) in the Synbiotic-treated groups. On day 18, mucosa, villi, villi-crypt ratio, crypt, and feed intake were influenced by Enterobacteriaceae. However, on day 39 (end of the trial), those parameters were influenced by lactic acid bacteria. The Synbiotic influenced morphological modifications in the duodenal mucosa, which in turn gave the broilers the ability to resist infections caused by S. Typhimurium and C. perfringens, by inhibiting their growth and decreasing the intensity and frequency of histopathological injuries.

Transcriptome analysis revealed ameliorative effect of probiotic Lactobacillus johnsonii BS15 against subclinical necrotic enteritis induced hepatic inflammation in broilers

Subclinical necrotic enteritis (SNE) broadly occurs in boilers, which reduces the growth performance by causing serious economic and social problems. The following study was conducted to better understand the molecular mechanism of the SNE on liver inflammation and to examine the innovative prevention of Lactobacillus johnsonii BS15 upon SNE. The research was based on the regulatory molecular mechanism of Lactobacillus johnsonii BS15, and its effect on liver inflammatory pathways in the broiler with SNE infection. Day old one hundred and eighty (Cobb 500) broiler chickens were distributed into 3 groups (control, SNE and BS15 group) and reared for 28 days. RNA sequencing was used for the analysis of gene expression extracted from liver samples. Gene expression was detected with the help of quantitative real-time PCR (qRT-PCR). RNA-Seq analysis revealed altered expressions of genes involved in liver inflammatory pathway. A total number of 385 genes were found as differentially expressed (DEGs) in the liver samples that belonged to SNE group as compared with the control liver samples (p < 0.05). Out of those 385 genes, 117 were down-regulated and 268 were up-regulated. The DEGs related to liver inflammation between control group and SNE group or SNE and BS15 groups, included cluster of differentiation 80 (CD80), Interleukin 1 beta (IL1B), Phosphoinositide 3- Kinase regulatory subunit 5 (PIK3R5), Toll-like receptor 4 (TLR4), Toll-like receptor 2 A (TLR2A), and proto-oncogene protein (FOS). The RNA-Seq analysis provided DEGs expression and this result was validated by qRT-PCR. Results confirmed that these genes are essential in the regulation of liver inflammation in the SNE infected chickens. Findings of current research indicated that the hepatic inflammation could be induced by SNE in broilers. Simultaneously, effects of SNE infection on liver could be subsided by improved TLRs signaling pathway with the naturally present prophylactic strategy as BS15.

Analysis of hepatic transcriptome demonstrates altered lipid metabolism following Lactobacillus johnsonii BS15 prevention in chickens with subclinical necrotic enteritis

Background

Subclinical necrotic enteritis (SNE) widely outbreaks in chickens which inflicted growth-slowing, causing enormous social and economic burdens. To better understand the molecular underpinnings of SNE on lipid metabolism and explore novel preventative strategies against SNE, we studied the regulatory mechanism of a potential probiotic, Lactobacillus johnsonii BS15 on the lipid metabolism pathways involved in chickens with SNE.

Methods

One hundred eighty one-day-old chickens were randomly divided into three groups and arranged with basal diet (control and SNE group). Added with BS15 (1 × 10⁶ cfu/g) or Man Rogosa Sharpe (MRS) liquid medium for 28 days. The hepatic gene expression of each group was then measured using high-throughput analysis methods (RNA-Seq). Quantitative real-time PCR (qRT-PCR) was used to detect the expression changes of the related genes.

Results

The results showed that there are eleven lipid metabolic pathways were found during the prevention of BS15 treatment in SNE chickens by RNA-Seq, including the peroxisome proliferator-activated receptor (PPAR) signaling pathway and arachidonic acid metabolism. BS15 notably facilitated the expressions of fatty acid binding protein 2 (FABP2), acyl-CoA synthetase bubblegum family member 1 (ACSBG1), perilipin 1 (PLIN1) and perilipin 2 (PLIN2), which were involved in PPAR signaling pathway of SNE chickens. Besides, suppression of phospholipase A2 group IVA (PLA2G4A) in arachidonic acid metabolism was observed in SNE chickens after BS15 prevention. The expression patterns of FABP2, ACSBG1, PLIN1, PLIN2 and PLA24G in qRT-PCR validation were consistent with RNA-Seq results.

Conclusions

These findings indicate that SNE may affect the hepatic lipid metabolism of chickens. Meanwhile, BS15 pretreatment may provide a prospective natural prophylaxis strategy against SNE through improving the PPAR signaling pathway and arachidonic acid metabolism.

Electronic supplementary material

The online version of this article (10.1186/s12944-018-0741-5) contains supplementary material, which is available to authorized users.

Probiotic Lactobacillus johnsonii BS15 Improves Blood Parameters Related to Immunity in Broilers Experimentally Infected with Subclinical Necrotic Enteritis

The probiotic strain Lactobacillus johnsonii BS15 could exert beneficial effects on growth performance, lipid metabolism, and intestinal microflora in healthy broilers and those afflicted with subclinical necrotic enteritis (SNE). In particular, BS15 prevents SNE by enhancing intestinal immunity. To further understand the immune regulatory mechanism of BS15, we evaluated its effects on the overall immunity of broilers by determining blood parameters in healthy and SNE broilers. In this study, two experiments were conducted. Experiment 1 involved a 42-day experimental period and used 450 1-day-old male chicks. The chicks were randomly divided into three groups and fed with a basal diet with or without 1 × 10⁵ or 10⁶ colony-forming units (cfu) BS15/g as feed. Experiment 2 involved a 28-day experimental period and used 180 1-day-old male chicks. The chicks were randomly allotted into three groups and given with or without 1 × 10⁶ cfu BS15/g BS15 as feed. SNE infection was treated in all broilers, except in those in the normal diet group. Antioxidant abilities, immunoglobulins, and cytokines in the serum were assessed. T-lymphocyte subsets in peripheral blood were also determined. The first experiment demonstrated that BS15 enhanced the antioxidant abilities; the serum levels of immunoglobulins, interleukin-2, and interferon-gamma; and CD3⁺CD4⁺ T-lymphocyte percentage in peripheral blood on day 21. However, limited significant changes were observed on day 42. The second experiment revealed that BS15 supplementation positively influenced the antioxidant abilities and increased the serum levels of immunoglobulins and cytokines that were affected by SNE. BS15 also positively affected T-lymphocyte subsets in peripheral blood during SNE infection. These findings suggest that BS15 supplementation may prevent SNE in broilers by improving blood parameters related to immunity and enhancing intestinal immunity. Furthermore, BS15 supplementation can improve blood parameters in healthy broilers, especially at the starter phase.

Bacillus licheniformis normalize the ileum microbiota of chickens infected with necrotic enteritis

Necrotic enteritis (NE) is a severe intestinal disease, which can change gut microbiota and result in a high cost for the poultry industry worldwide. However, little is known regarding how the gut microbiota of NE chicken ileum are changed by Bacillus licheniformis. This study was conducted to investigate how ileum microbiota structure was changed by B. licheniformis in broiler chickens challenged with Clostridium perfringens-induced NE through Illumina MiSeq sequencing. The broilers were randomly separated into four groups: the negative control group (NC), the positive control group (PC), the fishmeal and coccidia group (FC), and the PC group supplied with feed containing B. licheniformis (BL). Compared to the PC and FC, alpha diversity, beta diversity, and the bacterial taxa of the ileum microbiota were more similar in BL and NC. Some genera, which were related to the NE control, became insignificant in BL with NC, such as Lactobacillus, Lactococcus, Bacteroides, Ruminococcus and Helicobacter. The PICRUSt analysis revealed that a tumour suppressor gene, p53, which was negatively correlated with Helicobacter, was enriched in the BL group. Our findings showed that the ileum microbiota disorder caused by NE in chickens was normalized by dietary B. licheniformis supplementation.

Probiotic Enhanced Intestinal Immunity in Broilers against Subclinical Necrotic Enteritis

Along with banning of antibiotics, necrotic enteritis (NE), especially subclinical NE (SNE) whereby no clinical signs are present in chicks, has become one of the most threatening problems in poultry industry. Therefore, increasing attention has been focused on research and application of effective probiotic strains, as an alternative to antibiotics, to prevent SNE in broilers. In the present study, we evaluated the effects of Lactobacillus johnsonii BS15 on the prevention of SNE in broilers. Specifically, assessment determined the growth performance and indexes related to intestinal mucosal immunity in the ileum and cecal tonsil of broilers. A total of 300 1-day-old Cobb 500 chicks were randomly distributed into the following 5 groups: control group (fed with basal diet + de Man, Rogosa, and Sharpe liquid medium [normal diet]), SNE group (normal diet), BS15 group (basal diet + 1 × 10⁶ colony-forming units BS15/g as fed [BS15 diet]), treatment group (normal diet [days 1-28] + BS15 diet [days 29-42]), and prevention group (BS15 diet [days 1-28] + normal diet [days 29-42]) throughout a 42-day experimental period. SNE infection was treated for all chicks in the SNE, BS15, treatment, and prevention groups. The present results demonstrated that BS15 supplementation of feeds in BS15 and prevention groups exerted a positive effect on preventing negative influences on growth performance; these negative influences included low body weight gain and increased feed conversion ratio caused by SNE. Although no changes were detected in all determined indexes in cecal tonsils, BS15-treated broilers were free from SNE-caused damage in villi in the ileum. BS15 inhibited SNE-caused decrease in immunoglobulins in the ileum. In the lamina propria of ileum, T cell subsets of lymphocytes influenced by SNE were also controlled by BS15. BS15 affected antioxidant abilities of the ileum and controlled SNE-induced mitochondrion-mediated apoptosis by positively changing contents and/or mRNA expression levels of apoptosis-related proteins. These findings indicate that BS15 supplementation may prevent SNE-affected growth decline mainly through enhancing intestinal immunity in broilers.