Mucin dynamics and microbial populations in chicken small intestine are changed by dietary probiotic and antibiotic growth promoter supplementation

Effects of necrotic enteritis challenge on intestinal micro-architecture and mucin profile

1. This study investigated the effect of Eimeria spp./Clostridium perfringens induced necrotic enteritis and traditional antibiotic preventatives on intestinal micro-architecture and mucin profile. 2. A total of 600 Cobb 500 broiler chickens were randomly assigned to the following three groups: (i) unchallenged, (ii) challenged, and (iii) zinc bacitracin/monensin (ZnB/monensin) (n = 25 chickens/pen, 8 pens/group). The challenged and ZnB/monensin chickens were individually inoculated with Eimeria acervulina, E. maxima and E. tenella and C. perfringens type A (EHE-NE18) at 9 and 15 d post-hatch respectively, to induce necrotic enteritis. 3. The challenge procedure significantly decreased villus height, increased villus width and increased crypt depth in the challenged compared to the unchallenged chickens. Zinc bacitracin and monensin maintained villus-crypt structure similar to that of the unchallenged chickens. 4. Mucin profile was not affected by Eimeria spp./C. perfringens challenge as demonstrated by periodic acid-Schiff and high iron diamine-alcian blue pH 2 x 5 staining. Zinc bacitracin and monensin decreased the number of intestinal mucin-containing goblet cells. 5. Lectin histochemistry showed a trend towards greater Arachis hypogea (PNA) reactivity in unchallenged chickens. 6. In summary, Eimeria spp./C. perfringens challenge disrupted intestinal micro-architecture; however, challenge did not appear to affect intestinal mucin profile. Traditional antibiotics, zinc bacitracin and monensin maintained micro-architecture.

Resistant starch, large bowel fermentation and a broader perspective of prebiotics and probiotics

The metabolic end products of the large bowel microbiota contribute significantly to human health. After weaning to solid foods, some of the most important of these are the short chain fatty acids (SCFA) produced by the fermentation of undigested dietary components and endogenous secretions. The main SCFA are acetate, propionate and butyrate which have numerous documented effects promoting large bowel function. Of the major acids, butyrate seems especially important. It is a major metabolic fuel for colonocytes and promotes a normal phenotype in these cells, potentially lowering the risk of diseases such as colo-rectal cancer. Imbalances in the microbiota are thought to predispose to large bowel dysfunction and probiotics are being developed to correct this. However, most commercial products contain bacteria (lactobacilli and bifidobacteria) which are dominant species in milk-fed infants but have limited roles in adults. Prebiosis is defined usually by the specific stimulation of these bacteria. However, the end products of most probiotics do not include butyrate or propionate which raises questions about their effectiveness in promoting bowel health in adults. Resistant starch (RS) is a dietary fibre component and its fermentation generally favours butyrate production. Dietary RS intakes and faecal butyrate levels are high in populations at low risk of diet-related large bowel diseases. Conversely, RS intakes and faecal butyrate levels are very low in high risk groups. This raises the possibility that greater RS consumption could be of health benefit. RS is not regarded widely as a prebiotic but (according to the accepted definition) most forms show the requisite features in stimulating specific bacteria, giving raised total SCFA and butyrate levels and a consequent benefit to the host. Current efforts to improve public health through increasing RS consumption could be facilitated by greater recognition of its prebiotic role.

Modulations of the chicken cecal microbiome and metagenome in response to anticoccidial and growth promoter treatment

With increasing pressures to reduce or eliminate the use of antimicrobials for growth promotion purposes in production animals, there is a growing need to better understand the effects elicited by these agents in order to identify alternative approaches that might be used to maintain animal health. Antibiotic usage at subtherapeutic levels is postulated to confer a number of modulations in the microbes within the gut that ultimately result in growth promotion and reduced occurrence of disease. This study examined the effects of the coccidiostat monensin and the growth promoters virginiamycin and tylosin on the broiler chicken cecal microbiome and metagenome. Using a longitudinal design, cecal contents of commercial chickens were extracted and examined using 16S rRNA and total DNA shotgun metagenomic pyrosequencing. A number of genus-level enrichments and depletions were observed in response to monensin alone, or monensin in combination with virginiamycin or tylosin. Of note, monensin effects included depletions of Roseburia, Lactobacillus and Enterococcus, and enrichments in Coprococcus and Anaerofilum. The most notable effect observed in the monensin/virginiamycin and monensin/tylosin treatments, but not in the monensin-alone treatments, was enrichments in Escherichia coli. Analysis of the metagenomic dataset identified enrichments in transport system genes, type I fimbrial genes, and type IV conjugative secretion system genes. No significant differences were observed with regard to antimicrobial resistance gene counts. Overall, this study provides a more comprehensive glimpse of the chicken cecum microbial community, the modulations of this community in response to growth promoters, and targets for future efforts to mimic these effects using alternative approaches.

Intestinal mucin dynamic and leukocytic responses of chickens infected with Eimeria acervulina and fed oregano supplemented diet

We studied the effect of oregano supplemented diet on mucin dynamics in small intestine, peripheral blood leukocytes, and jejunal immunocompetent cells in ROSS 308 hybrid broilers infected withEimeria acervulinachickens’ oocyst. From the day of hatching chicks of groups 1 and 2 were fed a commercial diet without anticoccidial drug, the diet of group 3 was supplemented with oregano (0.707g·kg-1), and that of group 4 with anticoccidial drug (Robenidin hydrochloride – 33 mg·kg-1). Chickens of groups 2, 3, and 4 were inoculated withE. acervulinaoocysts (25.103) on day 12. The samples were collected on 3, 10, 17 days post infection (dpi). In blood on 3 dpi significant increase of leukocytes was found in group 3 compared to groups 1, 2, and 4, higher density of IgM+ cells in group 3 than group 2, and on 10 dpi phagocytic activity of group 3 was higher than group 1. Number of jejunal CD4+ and CD8+ cells in group 3 was consistent with values in group 4, despite higher density ofE. acervulinameronts on 10 dpi. The quantity of jejunal mucin adherent layer of group 3 was similar to that in group 4. Counts of oocysts in faeces were lower in group 3 than group 2. Results suggest that dietary supplementation of oregano to chickens infected withE. acervulinahas a modulating effect on some blood indicators and functions of phagocytes. The beneficial effect of oregano components on jejunal mucin quantity and its turnover is the first finding published in relation to oregano and coccidia.

Leukocytic responses and intestinal mucin dynamics of broilers protected with Enterococcus faecium EF55 and challenged with Salmonella Enteritidis

The protective effect of Enterococcus faecium EF55 in chickens challenged with Salmonella enterica serovar Enteritidis phage type 4 (SE PT4) was assessed. The antibacterial effect on the bacterial microflora in the small intestine in relation to white blood cell count, phenotyping of peripheral blood and intestinal lymphocytes, functional activity of lymphocytes and phagocytes and mucin quantitation were investigated. Day-old chicks (85) were randomly divided into four groups. The probiotic group (EF) and Salmonella+probiotic group (EFSE) received E. faecium EF55 (10(9) CFU - 3 g/group/day) for 21 days. The Salmonella group (SE) and EFSE group were infected with Salmonella Enteritidis (10(8) CFU in 0.2 ml PBS) in a single dose per os on day four of the experiment. The control group chicks (C) were fed a commercial diet without added bacteria. Supplementation of EF55 in the diet of the chickens in the EFSE group, challenged with S. Enteritidis, caused the density of the intestinal mucin layer to increase significantly in non-specific regions (duodenum and jejunum), but decrease significantly in target regions (caeca) for S. Enteritidis. Probiotic treatment also appeared to result in a significantly higher number of lymphocytes in peripheral blood and a tendency to increase CD3, CD4, CD8, and IgM positive cells 3 days post-infection with S. Enteritidis. The results demonstrated an antibacterial effect and suggested that EF55 had a moderating effect on intestinal mucin production and leukocytic response in the early phase of S. Enteritidis infection.

Identification and characterization of potential performance-related gut microbiotas in broiler chickens across various feeding trials

Three broiler feeding trials were investigated in order to identify gut bacteria consistently linked with improvements in bird performance as measured by feed efficiency. Trials were done in various geographic locations and varied in diet composition, broiler breed, and bird age. Gut microbial communities were investigated using microbial profiling. Eight common performance-linked operational taxonomic units (OTUs) were identified within both the ilea (180, 492, and 564-566) and ceca (140-142, 218-220, 284-286, 312, and 482) across trials. OTU 564-566 was associated with lower performance, while OTUs 140-142, 482, and 492 were associated with improved performance. Targeted cloning and sequencing of these eight OTUs revealed that they represented 26 bacterial species or phylotypes which clustered phylogenetically into seven groups related to Lactobacillus spp., Ruminococcaceae, Clostridiales, Gammaproteobacteria, Bacteroidales, Clostridiales/Lachnospiraceae, and unclassified bacteria/clostridia. Where bacteria were identifiable to the phylum level, they belonged predominantly to the Firmicutes, with Bacteroidetes and Proteobacteria also identified. Some of the potential performance-related phylotypes showed high sequence identity with classified bacteria (Lactobacillus salivarius, Lactobacillus aviarius, Lactobacillus crispatus, Faecalibacterium prausnitzii, Escherichia coli, Gallibacterium anatis, Clostridium lactatifermentans, Ruminococcus torques, Bacteroides vulgatus, and Alistipes finegoldii). The 16S rRNA gene sequence information generated will allow quantitative assays to be developed which will enable elucidations of which of these phylotypes are truly performance related. This information could be used to monitor strategies to improve feed efficiency and feed formulation for optimal gut health.

Histochemical features of the Muscovy duck small intestine during development

We demonstrated for the first time the distribution and morphology of argyrophil and of goblet cells in the mucosa of the small intestine of the Muscovy duck during development using the Grimelius silver staining and alcian blue/periodic acid-Schiff (AB/PAS) staining technique. The argyrophil cells distribution was variable over the length of the small intestine from embryonic day 24 (24E) to post-hatching day 13 (13d). In the villi most argyrophil cells belonged to the open-type, while in the crypts they belonged to the closed-type. In the duodenum the density of argyrophil cells was highest at hatching, while in the jejunum and in the ileum the highest density value was at hatching and 13d. AB/PAS-positive goblet cells appeared on the villi and crypts of the duodenum and jejunum at 30E, and in the ileum at hatching. The density of AB/PAS-positive cells was the highest in the three segments at hatching. The AB-positive cells, compared with the PAS-positive cells, predominated in villi and crypts of the three segments, moreover the rate of AB-positive cells to PAS-positive cells significantly decreased from 30E to 9d. An increase in argyrophil and goblet cells number during the later incubation and at hatching, could indicate the small intestine in that period is being prepared to face a new diet.

Effect of diets containing potato protein or soya bean meal on the incidence of spontaneously-occurring subclinical necrotic enteritis and the physiological response in broiler chickens

1. An experiment was conducted to compare and explain the incidence of spontaneously occurring subclinical necrotic enteritis in broiler chickens that were fed on two practical broiler diets that differed in the major protein concentrates (soya bean meal or potato protein concentrates) and examine the relationships between the severity of the disease and the growth performance and physiological responses of the chickens. 2. A total of 840, 20-d-old birds were randomly allocated to 12 pens. Two maize-based nutritionally complete diets that either contained some potato protein or soya bean meal as the major protein supplement were fed for 16 d. Twelve birds were randomly sampled from each pen at the end of the feeding period and their blood sampled and intestinal tracts and livers dissected. 3. The birds fed on the potato protein diet had a significantly 7·7% lower feed intake and a significantly 7·8% lower growth rate compared with the birds fed on the soya-based diet. There were no significant differences in feed conversion efficiency or mortality. There were no differences in the determined apparent metabolisable energy concentrations, however, the apparent dry matter digestibility of the potato protein diet was significantly higher than that of the soya based diet and the apparent crude protein digestibility of the potato protein diet was significantly lower. 4. A significantly higher alpha toxin antibody titre was found in the birds fed on the potato protein diet compared with those fed on the soya protein diet. There was a significantly increased incidence of hepatic lesions in the birds fed on the potato protein diet compared with the birds fed on the soya diet. The mean incidence of intestinal necroses tended to be greater in the birds fed on the potato protein diet (23·6%) compared with the birds fed on the soya-based diet (15·3%). 5. There was a significant linear relationship between ileal digesta sialic acid concentration and serum alpha toxin antibodies, although there were a considerable number of outliers to this relationship. Measurement of sialic acid concentration may be a useful variable to indicate the severity of necrotic enteritis in broiler flocks.

Inulin and probiotics in newly weaned piglets: effects on intestinal morphology, mRNA expression levels of inflammatory marker genes and haematology

The study aimed at determining the effect of inulin and/or a multispecies probiotic formulation on gastrointestinal tract (GIT) morphology, immunological and haematological parameters. Forty-eight newly weaned piglets were assigned to four feeding groups, receiving a standard basal diet (control), supplemented with 0.4% inulin, probiotics (1 x 10(9) CFU/kg as fed, enterococci, lactobacilli, bifidobacteria) or a combination of both (synbiotic). After four weeks of ad libitum feeding piglets were slaughtered and intestinal tissue samples were obtained for histometry. Additional tissue samples of the GIT, mesenteric lymph nodes, blood, liver and spleen were taken for mRNA expression analysis of cell turnover (CDK4, caspase3, IGF I), transcription factor NFkappaB and inflammatory marker genes (TNFalpha, TGFbeta). Changes in histometry occurred predominantly in the small intestine, showing higher jejunal villi when probiotics were administered alone (p < 0.10). Inulin decreased the number of acidic goblet cells in jejunal villi (p < 0.05), whereas probiotics increased neutral goblet cells in ileal villi (p < 0.05). Though inflammatory marker genes were uninfluenced by treatment in the proximal GIT, the colon showed downregulations induced by inulin (TNFalpha: p < 0.10, TGFbeta: p < 0.05). Gene expression of CDK4 was upregulated in the jejunum and of TGFbeta in the mesenteric lymph nodes in the probiotic groups. Interestingly, the probiotic group alone exhibited upregulations in cell turnover marker genes in the colon and blood. Furthermore, for numerous parameters, inulin and probiotics led to no synergistic but antagonistic interactions.

Metronidazole effects on microbiota and mucus layer thickness in the rat gut

Both mucus and mucosa-associated bacteria form a specific environment in the gut; their disruption may play a crucial role in the development of intestinal bowel disease (IBD). Metronidazole, an antibiotic used in the treatment of IBD, alters gut microbiota and reduces basal oxidative stress to proteins in colonic tissue of healthy rats. The aim of this study was to evaluate the impact of the altered microbiota due to the metronidazole on the thickness of the mucus layer. This study was performed in healthy untreated rats (control group) or rats treated by metronidazole (metronidazole-treated rats, 1 mg mL(-1) in drinking water for 7 days). Both PCR-temporal temperature gradient gel electrophoresis and quantitative PCR (qPCR) revealed an altered microbiota with an increase in bifidobacteria and enterobacteria in metronidazole-treated rats compared with control rats. Moreover, a dominant bifidobacterial species, Bifidobacterium pseudolongum, was detected. Using qPCR and FISH, we showed that bifidobacteria were also increased in the microbiota-associated mucosa. At the same time, the mucus layer thickness was increased approximately twofold. These results could explain the benefits of metronidazole treatment and warrant further investigations to define the role of bifidobacteria in the colonic mucosa.

The thickness of the intestinal mucous layer in the colon of rats fed various sources of non-digestible carbohydrates is positively correlated with the pool of SCFA but negatively correlated with the proportion of butyric acid in digesta

The present experiment aimed to study the influence of six sources of non-digestible carbohydrates (NDC) on the mucous layer in the colon of rats. The NDC sources used were as follows: cellulose (C); pectin (P); inulin; resistant starch (RS); barley hulls. The diets contained 108-140 g NDC/kg DM. A fibre-free (FF) diet served as a control. The diets were fed to forty-eight rats for 34-41 d. The thickness of the total mucous layer in the colon was increased (P < 0.05) in rats fed C, P and RS when compared with rats fed a FF diet. In the colon, positive correlations were observed between the total thickness of the mucous layer and the area of neutral mucins, the pool of SCFA and the pool of acetic acid, while it was negatively correlated with the proportion of butyrate. The total thickness of the mucous layer was not correlated with the MUC gene transcription. The transcription of the gene MUC2 was negatively correlated (P = 0.04), whereas the transcription of MUC3 was positively correlated (P = 0.05) with the butyrate pool in the caecum. No correlations between the MUC2 or MUC3 transcription and SCFA were found in the colon. Hence, the regulation of the MUC genes differs between the compartments of the hindgut and, within compartments, the MUC genes may be regulated differently. In conclusion, a diet providing a large pool of SCFA with a low proportion of butyrate in the colon stimulates the formation of a thick mucous layer, which probably benefits intestinal health.

Effects of a multi-strain probiotic (PrimaLac) on performance and antibody responses to Newcastle disease virus and infectious bursal disease virus vaccination in broiler chickens

The effects of the probiotic PrimaLac (Lactobacillus acidophilus, Lactobacillus casei, Enterococcus faecium and Bifidobacterium bifidium) was investigated on performance and immune responses to vaccination against Newcastle disease and infectious bursal disease in broiler chickens. Use of PrimaLac significantly (P<0.05) enhanced broiler performance by improving body weight and decreasing the feed conversion ratio. Although administration of the probiotic appeared to improve the antibody responses to Newcastle disease virus and infectious bursal disease vaccination, the antibody titres of the probiotic-treated group were not significantly different from those not receiving probiotics.

Interactions between commensal bacteria and the gut-associated immune system of the chicken

The chicken gut-associated lymphoid tissue is made up of a number of tissues and cells that are responsible for generating mucosal immune responses and maintaining intestinal homeostasis. The normal chicken microbiota also contributes to this via the ability to activate both innate defense mechanisms and adaptive immune responses. If left uncontrolled, immune activation in response to the normal microbiota would pose a risk of excessive inflammation and intestinal damage. Therefore, it is important that immune responses to the normal microbiota be under strict regulatory control. Through studies of mammals, it has been established that the mucosal immune system has specialized regulatory and anti-inflammatory mechanisms for eliminating or tolerating the normal microbiota. The mechanisms that exist in the chicken to control host responses to the normal microbiota, although assumed to be similar to that of mammals, have not yet been fully described. This review summarizes what is currently known about the host response to the intestinal microbiota, particularly in the chicken.

Comparative metagenomics reveals host specific metavirulomes and horizontal gene transfer elements in the chicken cecum microbiome

BACKGROUND

The complex microbiome of the ceca of chickens plays an important role in nutrient utilization, growth and well-being of these animals. Since we have a very limited understanding of the capabilities of most species present in the cecum, we investigated the role of the microbiome by comparative analyses of both the microbial community structure and functional gene content using random sample pyrosequencing. The overall goal of this study was to characterize the chicken cecal microbiome using a pathogen-free chicken and one that had been challenged with Campylobacter jejuni.

METHODOLOGY/PRINCIPAL FINDINGS

Comparative metagenomic pyrosequencing was used to generate 55,364,266 bases of random sampled pyrosequence data from two chicken cecal samples. SSU rDNA gene tags and environmental gene tags (EGTs) were identified using SEED subsystems-based annotations. The distribution of phylotypes and EGTs detected within each cecal sample were primarily from the Firmicutes, Bacteroidetes and Proteobacteria, consistent with previous SSU rDNA libraries of the chicken cecum. Carbohydrate metabolism and virulence genes are major components of the EGT content of both of these microbiomes. A comparison of the twelve major pathways in the SEED Virulence Subsystem (metavirulome) represented in the chicken cecum, mouse cecum and human fecal microbiomes showed that the metavirulomes differed between these microbiomes and the metavirulomes clustered by host environment. The chicken cecum microbiomes had the broadest range of EGTs within the SEED Conjugative Transposon Subsystem, however the mouse cecum microbiomes showed a greater abundance of EGTs in this subsystem. Gene assemblies (32 contigs) from one microbiome sample were predominately from the Bacteroidetes, and seven of these showed sequence similarity to transposases, whereas the remaining sequences were most similar to those from catabolic gene families.

CONCLUSION/SIGNIFICANCE

This analysis has demonstrated that mobile DNA elements are a major functional component of cecal microbiomes, thus contributing to horizontal gene transfer and functional microbiome evolution. Moreover, the metavirulomes of these microbiomes appear to associate by host environment. These data have implications for defining core and variable microbiome content in a host species. Furthermore, this suggests that the evolution of host specific metavirulomes is a contributing factor in disease resistance to zoonotic pathogens.

The short-term effects of different doses of dexamethasone on the numbers of some bacteria in the ileum

Glucocorticoids are known to affect intestinal biota both directly or indirectly. The aim of the study reported here was to determine the short-term effects of different doses of dexamethasone on the numbers of various ileal bacteria populations. Rats were randomly put into groups, and each group was administered a single-dose injection of dexamethasone at either 0.1, 0.5, 1, 2.5, 5, or 10 mg/kg body weight. At 48-h post-injection, the numbers of total aerobe, anaerobe, lactobacilli and coliform bacteria in the ileum were determined. The numbers of total aerobes and lactobacilli were higher in the groups receiving 5 and 10 mg/kg dexamethasone than in the control and other dose groups (P < 0.01 and P < 0.001, respectively). The number of ileal anaerobic bacteria was higher in group receiving 5 mg/kg than in the other groups (P < 0.01). There were more coliform bacteria in the group receiving 0.1 mg/kg than in the groups receiving 0.5, 1 and 10 mg/kg (P < 0.05). In light of these results, the effects of dose-dependent increases in the number of different bacterial groups affecting gut functions have still to be determined in future studies.

Dietary inulin affects the expression of intestinal enterocyte iron transporters, receptors and storage protein and alters the microbiota in the pig intestine

Inulin, a linear β fructan, is present in a variety of plants including chicory root and wheat. It exhibits prebiotic properties and has been shown to enhance mineral absorption and increase beneficial bacteria in the colon. The aim of the present study was to assess the effect of dietary inulin on the gene expression of selected intestinal Fe transporters and binding proteins. Anaemic piglets at age 5 weeks were allocated to a standard maize–soya diet (control) or the same diet supplemented with inulin at a level of 4 %. After 6 weeks, the animals were killed and caecum contents and sections of the duodenum and colon were removed. Segments of the genes encoding for the pig divalent metal transporter 1 (DMT1) and duodenal cytochrome-b reductase (Dcytb) were isolated and sequenced. Semi-quantitative RT-PCR analyses were performed to evaluate the expression of DMT1, Dcytb, ferroportin, ferritin, transferrin receptor (TfR) and mucin genes. DMT1, Dcytb, ferroportin, ferritin and TfR mRNA levels in duodenal samples were significantly higher in the inulin group (P ≤ 0·05) compared with the control. In colon, DMT1, TfR and ferritin mRNA levels significantly increased in the inulin group. Additionally, the caecal content microflora was examined using 16S rDNA targeted probes from bacterial DNA. TheLactobacillusandBifidobacteriumpopulations were significantly increased in the inulin group (P ≤ 0·05) compared with the control group. These results indicate that dietary inulin might trigger an up regulation of genes encoding for Fe transporters in the enterocyte. The specific mechanism for this effect remains to be elucidated.

Multifaceted transcriptional regulation of the murine intestinal mucus layer by endogenous microbiota

The intestinal mucus layer and endogenous microbiota are strongly intertwined and this contributes to the maintenance of the epithelial barrier and ultimately of gut homeostasis. To understand the molecular foundations of such relationship, we investigated if the nature of the microbiota transcriptionally regulates mucus layer composition in vivo. We found that the expression of mucins 1 to 4 and trefoil factor 3 was down-regulated in the ileum and colon of conventional and reconventionalized mice compared with germ-free animals. Conversely, very limited colon-restricted changes in transmembrane mucins were detected in mice colonized with human adult or baby microbiota. Moreover, by microarray analysis, the murine endogenous microbiota was found to modulate genes putatively involved in mucin secretion. These findings show that a well-established microbial community participates in the regulation of the gut mucus layer and that its composition and adequacy to the host are key factors in this process.

Effects of purified lignin and mannan oligosaccharides on intestinal integrity and microbial populations in the ceca and litter of broiler chickens

A study was conducted to evaluate lignin and mannan oligosaccharides as potential alternatives to antibiotic growth promoters in broilers. Dietary treatments included an antibiotic-free diet (CTL-), a positive control (CTL+, 11 mg/kg of virginiamycin), and an antibiotic-free diet containing BioMos (MOS, 0.2% to 21 d and 0.1% thereafter) or Alcell lignin at 1.25% (LL) or 2.5% (HL) of the diet. Each treatment was randomly assigned to 4 floor pen replicates (40 birds each). Body weight and feed conversion were recorded weekly throughout 42 d. Jejunum histology was analyzed at d 14, 28, and 42. At d 28 and 42, cecal contents were assayed for Escherichia coli, Salmonella, lactobacilli, and bifidobacteria, and the litter was analyzed for E. coli and Salmonella. Birds fed the CTL- diet were heavier (P<0.05) than those fed the other dietary treatments, but feed conversion was not affected by dietary treatments. Birds fed MOS and LL had increased jejunum villi height and a higher number of goblet cells per villus (P<0.05) when compared with those fed the CTL+ diet. At d 42, birds fed MOS, LL, or HL had greater lactobacilli numbers than those fed the CTL+ diet. Compared with the CTL+ diet, the MOS diet increased the populations of bifidobacteria (P<0.05) in the ceca. Litter E. coli load was lower in birds fed MOS (P<0.05) than in birds fed the CTL+ diet but comparable to that of birds fed the LL or HL diet. Broiler performance was similar in birds fed antibiotics or antibiotic-free diets containing either MOS or lignin. However, birds fed MOS and LL had a comparative advantage over birds fed antibiotics as evidenced by an increased population of beneficial bacteria in the ceca, increased villi height and number of goblet cells in the jejunum, and lower population of E. coli in the litter.

A deficiency or excess of dietary threonine reduces protein synthesis in jejunum and skeletal muscle of young pigs

Dietary threonine imbalance is known to reduce the growth of the small intestine, liver, and skeletal muscle in young animals, but the underlying mechanism is largely unknown. Using the pig model, this study was conducted to test the hypothesis that either a deficiency or an excess of dietary threonine impairs protein synthesis in these tissues. Young pigs (25 d of age) were fed diets containing 0.37, 0.74 (current NRC requirement) or 1.11% true ileal digestible threonine (TIDT) (n = 6/diet). Pigs receiving the 0.74 and 1.11% TIDT diets were pair-fed with the same amount of feed as pigs receiving the 0.37% TIDT diet. After a 14-d dietary treatment, the fractional synthesis rate (FSR) of protein in tissues was measured using a flooding dose of l-phenylalanine plus L-[ring-(2)H(5)]phenylalanine. The results indicated that the FSR of protein in liver was reduced (P < 0.05) in pigs fed the 0.37% TIDT diet compared with pigs fed the 0.74 or 1.11% TIDT diet, and did not differ between pigs fed the 0.74 and 1.11% TIDT diets. The FSR of protein in longissimus muscle, jejunal mucosa, and mucins was reduced (P < 0.05) in pigs fed the 0.37 or 1.11% TIDT diet compared with pigs fed the 0.74% TIDT diet. The absolute synthesis rate of protein in the jejunal mucosa and muscle was also reduced (P < 0.01) in pigs fed the 0.37 and 1.11% TIDT diets compared with the controls. The absolute synthesis rate of hepatic protein was lower (P < 0.01) in pigs fed the 0.37% TIDT diets when compared with pigs fed the 0.74% TIDT diet. Protein synthesis in skeletal muscle as well as jejunal mucosa and mucins was reduced to a greater extent than that in liver in response to an imbalance of dietary threonine. Collectively, these results indicate that either an excess or a deficiency of dietary threonine decreases protein synthesis in rapidly growing tissues of young pigs. The findings provide a mechanism for the low growth performance of animals fed a threonine-imbalanced diet.

Gastrointestinal Maturation is Accelerated in Turkey Poults Supplemented with a Mannan-Oligosaccharide Yeast Extract (Alphamune)

Alphamune, a yeast extract antibiotic alternative, has been shown to stimulate the immune system, increase BW in pigs, and reduce Salmonella colonization in chickens. The influence of Alphamune on gastrointestinal tract development has not been reported. Two trials were conducted to evaluate the effects of Alphamune on gut maturation of 7- and 21-d-old turkey poults. Poults were fed a standard control unmedicated turkey starter diet or the same diet supplemented with either 1 or 2 lb/ton of Alphamune (n = 18/group). Poults were weighed on d 7 and 21, euthanized, and a 2-cm section was collected from the midpoint of the duodenum, jejunum, and ileum of each bird (9 poults/d per treatment) and fixed in a 10% formalin solution for 72 h and then stained. Twenty measurements of villus height, villus surface area, lamina propria thickness, crypt depth, and density of neutral, sialomucin, and sulfomucin goblet cells were taken per section per poult. On d 7, BW were higher for the poults given the Alphamune treatments compared with control poults; however, no differences were observed on d 21. Alphamune supplementation influenced intestinal morphology differently based on gut location. Ileum villus height, surface area, lamina propria thickness, crypt depth, and neutral, sialomucin, and sulfomucin goblet cell density were enhanced with Alphamune treatments on d 7 and 21 (P < 0.05) and in a dose-dependent manner for many of the parameters evaluated. Jejunum results were mixed. Surface area, crypt depth, and sialomucin and sulfomucin goblet cells were consistently higher for the 2 lb/ton of Alphamune groups compared with the control group on d 7 and 21. Duodenum villus height, surface area, and goblet cell density were higher for the 2 lb/ton of Alphamune groups on d 7; however, intestinal morphology of the duodenum was not different between the control and treated birds on d 21. These results suggest that feed supplemented with Alphamune can accelerate gastrointestinal maturation in turkey poults and is more pronounced in the ileum than in other portions of the small intestine.

16S rRNA gene-based analysis of mucosa-associated bacterial community and phylogeny in the chicken gastrointestinal tracts: from crops to ceca

Mucosa-associated microbiota from different regions of the gastrointestinal (GI) tract of adult broilers was studied by analysis of 16S rRNA gene sequences. The microbiota mainly comprised Gram-positive bacteria along the GI tract. Fifty-one operational taxonomic units (OTUs) (from 98 clones) were detected in the ceca, as compared with 13 OTUs (from 49 clones) in the crops, 11 OTUs (from 51 clones) in the gizzard, 14 OTUs (from 52 clones) in the duodenum, 12 OTUs (from 50 clones) in the jejunum and nine OTUs (from 50 clones) in the ileum. Ceca were dominantly occupied by clostridia-related sequences (40%) with other abundant sequences being related to Faecalibacterium prausnitzii (14%), Escherichia coli (11%), lactobacilli (7%) and Ruminococcus (6%). Lactobacilli were predominant in the upper GI tract and had the highest diversity in the crop. Both Lactobacillus aviarius and Lactobacillus salivarius were the predominant species among lactobacilli. Candidatus division Arthromitus was also abundant in the jejunum and ileum.

Genetics of the innate immune response in inflammatory bowel disease

The discovery of nucleotide-binding oligomerization domain 2/caspase recruitment domain-containing protein 15 (NOD2/CARD15) as the first susceptibility gene in Crohn's disease (CD) has shifted the focus of research into the pathogenesis of inflammatory bowel disease (IBD) firmly to the innate immune response and the integrity of the epithelial barrier. The subsequent implication in IBD of variant alleles of OCTN, DLG5, MDR1, and TLRs has provided further support for a new, more complex model of innate immunity function in the gastrointestinal tract. In this review, we examine the recent advances in our understanding of the influence of genetics of the innate immune response on IBD. We will focus on germline variation of genes encoding pathogen-recognition receptors, proteins involved in epithelial homeostasis and secreted antimicrobial proteins.

Influence of dietary zinc and copper on digestive enzyme activity and intestinal morphology in weaned pigs1

The current study was conducted to investigate the effects of high dietary concentrations of Zn as zinc oxide and Cu as copper sulfate on the activity of digestive enzymes in the pancreas and the intestinal mucosa, intestinal morphology, and mucin histochemistry in pigs after weaning. Thirty-two pigs were weaned at 4 wk of age. The pigs were fed standard weaning diets supplemented with Zn (100 or 2,500 ppm) and Cu (0 or 175 ppm) in a 2 x 2 factorial arrangement of treatments for a 14-d period. In pancreatic tissue, the activity of amylase, carboxypeptidase A, chymotrypsin, trypsin, and lipase increased (P < 0.01) in pigs fed 2,500 ppm of Zn, whereas the activity of carboxypeptidase B and carboxylester hydrolase was unaffected. Copper had no effect on the activity of pancreatic enzymes. In small intestinal contents, the total activity of amylase and carboxypeptidase A was greater in pigs fed 100 ppm of Zn (P < 0.05), whereas feeding 2,500 ppm of Zn increased the chymotrypsin activity (P < 0.001). The remaining enzymes were unaffected by dietary Zn concentration. The villi were longer in the cranial small intestine (P < 0.001) in pigs fed 100 ppm of Zn than in pigs fed 2,500 ppm of Zn, but otherwise there were no clear effects of Zn and Cu supplementation on intestinal morphology. In the cranial small intestine, the activity of maltase (P < 0.001), sucrase (P < 0.001), and lactase was greater in pigs fed 100 ppm of Zn, even though there was a Zn x Cu interaction (P < 0.05) in lactase activity. In the middle and caudal small intestine, no clear differences between dietary treatments were observed. The activity of gamma-glutamyl transpeptidase in the intestinal mucosa was not affected by dietary Zn or Cu. In pigs fed 100 ppm of Zn, the activity of aminopeptidase N was greater in the caudal small intestine, but dietary Zn or Cu had no effect on aminopeptidase N in the cranial and middle small intestine. No effect of dietary Zn or Cu supplementation was found on carbohydrate histochemistry in the caudal small intestine, whereas high dietary Zn increased the area of neutral, acidic, and sulfomucins in the cecum (P < 0.01) and in the colon (P < 0.001). In summary, high dietary Zn increased the activity of several enzymes in the pancreatic tissue and increased the mucin staining area in the large intestine, whereas Cu had no clear effect on these variables. However, no definite answers were found as to how the growth promoting and diarrhea reducing effects of excess dietary Zn are exerted.

Effect of addition of a probiotic microorganism to broiler diets contaminated with deoxynivalenol on performance and histological alterations of intestinal villi of broiler chickens

An experiment was conducted to study the effects of deoxynivalenol (DON) on the performance of broilers, organ weights, and intestinal histology and to evaluate the efficacy of a probiotic feed additive (PB, Eubacterium sp.) with the ability to deepoxidize DON. Two hundred seventy-seven 1-d-old broiler chicks were randomly assigned to 1 of the 3 dietary treatments for 6 wk. The dietary treatments were 1) control; 2) artificially contaminated diets with 10 mg of DON/kg of diet; 3) DON-contaminated diets plus probiotic feed additive (DON-PB). The BW and the efficiency of feed utilization were not adversely affected (P > 0.05) by the inclusion of DON in the diets. A slight improvement in feed intake and BW gain over the course of the experiment was observed in broilers fed DON-PB with no change in feed efficiency. The absolute or relative organ weights were not altered (P > 0.05) in broilers fed the diet containing DON compared with controls and the DON-PB group. The absolute liver weights were numerically increased (P < 0.1) for broilers receiving the diet containing DON-PB. There were no significant differences in the absolute and relative weights of the gizzard, duodenum, pancreas, heart, and spleen. However, the absolute and relative weights of the jejunum and cecum were increased for DON-PB-fed broilers compared with the controls and DON group. No pathological lesions were found in the gut of birds fed DON-contaminated diets during the feeding trial, but mild intestinal changes were observed. The DON altered small intestinal morphology, especially in the duodenum and jejunum, where villi were shorter and thinner (P < 0.05). The addition of the eubacteria to the DON-contaminated feed of the broilers effectively alleviated the histological alterations caused by DON and led to comparable villus length as in the control group. In conclusion, diets with DON contamination below levels that induce a negative impact on health and performance could affect small intestinal morphology in broilers. The histological alterations caused by DON were reduced by supplementing the DON-containing diets with PB. This indicates that in case of DON contamination of feedstuffs, the addition of PB would be a proper way to counteract the possible effects caused by this mycotoxin.