Expression of genes related to ileal barrier function in heritage and modern broiler chickens

1. An experiment was conducted to determine differences in the expression of genes encoding intestinal barrier proteins between fast, medium and slow-growing chickens. Chicken breeds Athens Canadian Random Bred (ACRB), Longenecker's Heritage (LHR), RedBro, Hubbard H1 (HH1), Cobb500 and Ross708 were raised from hatch for 35 d.2. Ileal samples were collected at embryonic day E19 (-2 days post-hatch), hatch and d 7, 14, 21, 28 and 35 post-hatch to assess the expression of genes encoding tight junction proteins (claudins, CLDN; occludin, OCLN; zonula occludens, ZO; and junctional adhesion molecules, JAM), mucin (Muc2), immunoglobulin A (IgA), polymeric immunoglobulin receptor (pIgR) and fatty acid binding protein (FABP2).3. Expression of CLDN-1 was increased (p < 0.0001) in LHR compared to Cobb500 while CLDN-5 was increased (p < 0.0001) in ACRB, HH1, RedBro and Ross708 compared to LHR as well as in ACRB compared to Cob500. Occludin was upregulated (p = 0.01) in ACRB and LHR compared to Ross708 at d 14 post-hatch. Expression of ZO-1 was upregulated (p = 0.001) in LHR compared to Ross708, HH1 and Cobb500. Tight junction genes, except CLDN-4, JAM-2 and JAM-3 were downregulated (p < 0.0001) at hatch and d 7 post-hatch. Expression of Muc2 was increased (p < 0.0001) in LHR compared to RedBro and from -2 d to d 7 post-hatch.4. Immunoglobulin A was increased (p = 0.001) in LHR compared to Ross708 and HH1 at -2 d post-hatch and in LHR compared to ACRB, Cobb500 and Ross708 at hatch. In addition, IgA expression was increased in all breeds at d 14 post-hatch while pIgR was upregulated (p = 0.02) in Cobb500 and Ross708 compared to ACRB, HH1, LHR and RedBro at hatch.5. The gene expression patterns suggest that selection for growth may have not induced changes in junctional complexes and immune defence genes. However, the results confirmed that the expression of these genes is age dependent.

Effect of lipopolysaccharides from pathogenic bacteria on broiler chickens' productivity: a meta-analysis

1. This meta-analysis investigated the impact of LPS and covariates (serotype, rearing period and administration route) on the productivity parameters of broiler chickens (average daily feed intake (ADFI), average daily gain (ADG) and feed conversion ratio (FCR)).2. Thirty-two eligible studies were included. Hedges' g effect size was determined using a random-effects model at 95% confidence interval.3. Results showed that LPS significantly decreased average daily feed intake (ADFI; p < 0.0001) and average daily gain (ADG; p < 0.0001) and increased FCR (p < 0.0001). The serotypes Escherichia coli 055: B5 (EC055: B5) and Escherichia coli 0127: B8 (EC 0127: B8) significantly reduced ADFI and ADG, and the serotype EC 055: B5 significantly increased the FCR (p < 0.05).4. The intraperitoneal administration of the LPS significantly reduced the productivity of broiler chickens (p < 0.05), but other administration routes did not show such effects. The reduction in ADFI and ADG was found in all rearing periods (p < 0.05), and the increase in FCR was observed in the starter (p = 0.0302) and grower periods (p = 0.0031).5. Exposure to LPS significantly reduced the productivity of broiler chickens (p < 0.05). However, no relationship was observed between LPS dosage and productivity as indicated by the meta-regression study.6. The findings indicated that LPS has detrimental effects on broiler chickens' ADFI, ADG and FCR across various LPS serotypes and rearing periods. These detrimental impacts of LPS remain consistent regardless of the administered dosage.

Modulation of chicken gut microbiota for enhanced productivity and health: A review

Microbiota in the digestive tract has become an interesting topic for researchers in recent years. The profile of chicken digestive tract microbiota and its relationship with health and production efficiency have become basic data for modulating the diversity and abundance of the digestive tract microbiota. This article reviews the techniques used to analyze the diversity, role, and function of the gastrointestinal microbiota and the mechanisms by which they are modulated. The gut microbiota plays an important role in animal production, especially during feed digestion and animal health, because it interacts with the host against pathogens. Feed modulation can be a strategy to modulate gut composition and diversity to increase production efficiency by improving growth conditions.

Metagenome-assembled genome reveals species and functional composition of Jianghan chicken gut microbiota and isolation of Pediococcus acidilactic with probiotic properties

BACKGROUND

Chickens are one of the most widely farmed animals worldwide and play a crucial role in meat and egg production. Gut microbiota is essential for chickens' health, disease, growth, and egg production. However, native chickens such as Jianghan chickens have better meat and egg production quality than centralized chickens, their intestinal microbial diversity is richer, and the potential gut microbial resources may bring health benefits to the host.

RESULTS

The bacterial species composition in the gut microbiota of Jianghan chickens is similar to that of other chicken breeds, with Phocaeicola and Bacteroides being the most abundant bacterial genera. The LEfSe analysis revealed significant differences in species composition and functional profiles between samples from Jingzhou and the other three groups. Functional annotation indicated that the gut microbiota of Jianghan chickens were dominated by metabolic genes, with the highest number of genes related to carbohydrate metabolism. Several antibiotic resistance genes (ARGs) were found, and the composition of ARGs was similar to that of factory-farmed chickens, suggesting that antibiotics were widely present in the gut microbiota of Jianghan chickens. The resistance genes of Jianghan chickens are mainly carried by microorganisms of the Bacteroidota and Bacillota phylum. In addition, more than 829 isolates were selected from the microbiota of Jianghan chickens. Following three rounds of acid and bile tolerance experiments performed on all the isolated strains, it was determined that six strains of Pediococcus acidilactici exhibited consistent tolerance. Further experiments confirmed that three of these strains (A4, B9, and C2) held substantial probiotic potential, with P. acidilactici B9 displaying the highest probiotic potential.

CONCLUSIONS

This study elucidates the composition of the intestinal microbiota and functional gene repertoire in Jianghan chickens. Despite the absence of antibiotic supplementation, the intestinal microbial community of Jianghan chickens still demonstrates a profile of antibiotic resistance genes similar to that of intensively reared chickens, suggesting resistance genes are prevalent in free-ranging poultry. Moreover, Jianghan and intensively reared chickens host major resistance genes differently, an aspect seldom explored between free-range and pastured chickens. Furthermore, among the 829 isolates, three strains of P. acidilatici exhibited strong probiotic potential. These findings provide insights into the unique gut microbiota of Jianghan chickens and highlight potential probiotic strains offering benefits to the host. Video Abstract.

Osteoimmunology: A Link between Gastrointestinal Diseases and Skeletal Health in Chickens

Bone serves as a multifunctional organ in avian species, giving structural integrity to the body, aiding locomotion and flight, regulating mineral homeostasis, and supplementing calcium for eggshell formation. Furthermore, immune cells originate and reside in the bone marrow, sharing a milieu with bone cells, indicating a potential interaction in functions. In avian species, the prevalence of gastrointestinal diseases can alter the growth and the immune response, which costs a great fortune to the poultry industry. Previous studies have shown that coccidiosis and necrotic enteritis can dramatically reduce bone quality as well. However, possible mechanisms on how bone quality is influenced by these disease conditions have not yet been completely understood, other than the reduced feed intake. On the other hand, several mediators of the immune response, such as chemokines and cytokines, play a vital role in the differentiation and activation of osteoclasts responsible for bone resorption and osteoblasts for bone formation. In the case of Eimeria spp./Clostridium perfringens coinfection, these mediators are upregulated. One possible mechanism for accelerated bone loss after gastrointestinal illnesses might be immune-mediated osteoclastogenesis via cytokines-RANKL-mediated pathways. This review article thus focuses on osteoimmunological pathways and the interaction between host immune responses and bone biology in gastrointestinal diseases like coccidiosis and necrotic enteritis affecting skeletal health.

State of the art in research on the gut-liver and gut-brain axis in poultry

The relationship between the intestines and their microbiota, the liver, and the neuronal system is called the gut-liver-brain axis. This relationship has been studied and observed for a relatively short time but is considered in the development of research focused on, e.g., liver diseases and intestinal dysbiosis. The role of the gut microbiota in this relationship is crucial, as it acts on poultry's performance and feed utilization, affecting meat and egg quality. The correct composition of the intestinal microbiota makes it possible to determine the essential metabolic pathways and biological processes of the individual components of the microbiota, allowing further speculation of the role of microbial populations on internal organs such as the liver and brain in the organism. The gut microbiota forms a complex, dense axis with the autonomic and enteric nervous systems. The symbiotic relationship between the liver and gut microbiota is based on immune, metabolic and neuroendocrine regulation, and stabilization. On the other hand, the gut-brain axis is a bidirectional interaction and information transfer system between the gastrointestinal tract and the central nervous system. The following paper will discuss the current state of knowledge of the gut-liver-brain axis of poultry, including factors that may affect this complex relationship.

Pioneer colonizers: Bacteria that alter the chicken intestinal morphology and development of the microbiota

Microbes commonly administered to chickens facilitate development of a beneficial microbiome that improves gut function, feed conversion and reduces pathogen colonization. Competitive exclusion products, derived from the cecal contents of hens and shown to reduce Salmonella colonization in chicks, possess important pioneer-colonizing bacteria needed for proper intestinal development and animal growth. We hypothesized that inoculation of these pioneer-colonizing bacteria to day of hatch chicks would enhance the development of their intestinal anatomy and microbiome. A competitive exclusion product was administered to broiler chickens, in their drinking water, at day of hatch, and its impact on intestinal morphometrics, intestinal microbiome, and production parameters, was assessed relative to a control, no treatment group. 16S rRNA gene, terminal restriction fragment length polymorphism (T-RFLP) was used to assess ileal community composition. The competitive exclusion product, administered on day of hatch, increased villus height, villus height/width ratio and goblet cell production ∼1.25-fold and expression of enterocyte sugar transporters 1.25 to 1.5-fold in chickens at 3 days of age, compared to the control group. As a next step, chicks were inoculated with a defined formulation, containing Bacteroidia and Clostridia representing pioneer-colonizing bacteria of the two major bacterial phyla present in the competitive exclusion product. The defined formulation, containing both groups of bacteria, were shown, dependent on age, to improve villus height (jejunum: 1.14 to 1.46-fold; ileum: 1.17-fold), goblet cell numbers (ileum 1.32 to 2.51-fold), and feed efficiency (1.18-fold, day 1) while decreasing Lactobacillus ileal abundance by one-third to half in birds at 16 and 42 days of age, respectively; compared to the phosphate buffered saline treatment group. Therefore, specific probiotic formulations containing pioneer colonizing species can provide benefits in intestinal development, feed efficiency and body weight gain.

Differences in gut bacterial community composition between modern and slower-growing broiler breeder lines: Implications of growth selection on microbiome composition

In the last century broiler chicken lines have undergone an extensive breeding regime aimed primarily at growth and high meat yield. It is not known if breeding has also resulted in a change to the broiler breeder's associated gut microbiota. Here we compared the gut microbiota of 37-week-old commercial Cobb breeding dams with dams from a broiler Legacy line which has not undergone selection since 1986. The dams from both lines were kept together in the same shed under the same management protocol from day of hatch to avoid additional confounders. We chose this age to allow significant bacterial exchange, thus avoiding exposure dependent artifacts and so that we could compare dams at the same developmental state of adulthood and peak laying performance. Significant differences in the composition of the cecum bacterial communities were found. Bacteria of the genus Akkermansia, implicated in mucin degradation and associated with host metabolic health, accounted for 4.98% ± 5.04% of the Cobb cecum community, but were mostly absent from the ceca of the Legacy line dams. Inversely, Legacy dams had higher levels of Clostridiales, Lactobacillales and Aeromonadales. These results show that breeding has resulted in a change in the gut microbiota composition, likely by changing the physiological conditions in the mucosa. It remains unclear if changes in gut microbiota composition are a part of the mechanism affecting growth or are a secondary result of other physiological changes accelerating growth. Therefore, the identification of these changes opens the door to further targeted research.

Pathogenesis from the microbial-gut-brain axis in white matter injury in preterm infants: A review

White matter injury (WMI) in premature infants is a unique form of brain injury and a common cause of chronic nervous system conditions such as cerebral palsy and neurobehavioral disorders. Very preterm infants who survive are at high risk of WMI. With developing research regarding the pathogenesis of premature WMI, the role of gut microbiota has attracted increasing attention in this field. As premature infants are a special group, early microbial colonization of the microbiome can affect brain development, and microbiome optimization can improve outcomes regarding nervous system development. As an important communication medium between the gut and the nervous system, intestinal microbes form a microbial-gut-brain axis. This axis affects the occurrence of WMI in premature infants via the metabolites produced by intestinal microorganisms, while also regulating cytokines and mediating oxidative stress. At the same time, deficiencies in the microbiota and their metabolites may exacerbate WMI in premature infants. This confers promise for probiotics and prebiotics as treatments for improving neurodevelopmental outcomes. Therefore, this review attempted to elucidate the potential mechanisms behind the communication of gut bacteria and the immature brain through the gut-brain axis, so as to provide a reference for further prevention and treatment of premature WMI.

The Development of Gut Microbiota and Its Changes Following C. jejuni Infection in Broilers

The gut is home to more than millions of bacterial species. The gut bacteria coexist with the host in a symbiotic relationship that can influence the host's metabolism, nutrition, and physiology and even module various immune functions. The commensal gut microbiota plays a crucial role in shaping the immune response and provides a continuous stimulus to maintain an activated immune system. The recent advancements in high throughput omics technologies have improved our understanding of the role of commensal bacteria in developing the immune system in chickens. Chicken meat continues to be one of the most consumed sources of protein worldwide, with the demand expected to increase significantly by the year 2050. Yet, chickens are a significant reservoir for human foodborne pathogens such as Campylobacter jejuni. Understanding the interaction between the commensal bacteria and C. jejuni is essential in developing novel technologies to decrease C. jejuni load in broilers. This review aims to provide current knowledge of gut microbiota development and its interaction with the immune system in broilers. Additionally, the effect of C. jejuni infection on the gut microbiota is addressed.

Bacterial lipopolysaccharide with different administration routes affects intestinal mucosal morphological, immunological, and microbial barrier functions in goslings

The current study was conducted to evaluate the effects of different administration routes of bacterial lipopolysaccharide (LPS) on intestinal mucosal morphological, immunological, and microbial barrier functions in goslings. First, we compared intestinal villi morphology of goslings under intraperitoneal or oral LPS treatment through hematoxylin and eosin staining. Then, we determined the signatures of the microbiome in the ileum mucosa of goslings subjected to oral LPS treatment at 0, 2, 4, and 8 mg/kg BW by 16S sequencing, and analyzed the changes in intestinal barrier functions and permeability, levels of LPS in the ileum mucosa, plasma, and liver tissue, and the induced inflammatory response of Toll-like receptor 4 (TLR4). As a result, intraperitoneal LPS injection resulted in a thicker intestinal wall in the ileum within a short time, whereas villus height was less affected; in contrast, oral LPS treatment exerted a stronger influence on villus height but not on intestinal wall thickness. We also found that oral LPS treatment affected the structure of the intestinal microbiome, reflected by changes in the clustering of intestinal microbiota. The average abundance of Muribaculaceae showed an increasing trend with increasing LPS levels, and that of the genus Bacteroides decreased, compared with the control group. In addition, oral LPS treatment with 8 mg/kg BW affected the intestinal epithelial morphology, damage the mucosal immune barrier, downregulated the expression of tight junction proteins, increased circulating D-lactate levels, and stimulated the secretion of various inflammatory mediators and activation of the TLR4/MyD88/NFκB pathway. This study presented the injuries of intestinal mucosal barrier function induced by LPS challenges in goslings and provided a scientific model for searching the novel strategies to attenuate the immunological stress and gut injury caused by LPS.

Effect of the Addition of Humic Substances on Morphometric Analysis and Number of Goblet Cells in the Intestinal Mucosa of Broiler Chickens

The mechanisms of action of humic substances (HS) as growth promoters in poultry are unknown. In this study, the productive performance, histology, and number of goblet cells (GC) in the intestinal villi of broilers under steady-state digestive conditions and under abrupt changes in diet with the addition of HS was evaluated. Broilers housed individually were offered three treatments from 14−28 days: 1 = diet with white corn/soybean meal, without growth promoter antibiotics (nonGPA); 2 = with GPA (GPA); and 3 = with 0.3% HS. At day 28, two diets were suddenly introduced: (A) white corn/soybean meal plus dried distillers’ grains with solubles (DDGS); and (B) white/blue corn/soybean meal/DDGS, keeping the three original treatments. Diets A and B were also exchanged on day 37. FCR was lower with GPA and HS compared to nonGPA from 14−38 days (p < 0.05); at day 28, under steady-state digestive conditions, HS had a similar effect to GPA on the histology and GC number in the jejunum villi. The number of GC in the jejunum of HS-fed broilers on days 29 and 38, after diet changes, behaves similarly to that of AGP-fed broilers (p > 0.05). HS appears to strengthen the mucosal protection of the epithelium of the intestine.

Comparative biology of germ-free and conventional poultry

Interaction between the host and the enteric microbiome is highly complex. Microbial involvement in certain pathologies is moderately well established, but the contribution of the microbiome to animal welfare, behavior, sustainability, immune development, nutritional status, physiology, and maturation is less clear. A valuable experimental model to enable scientists to explore the role of the microbiome in various domains is to compare various phenotypes of a conventionally reared (CV) cohort with those in a germ-free (GF) state. A GF animal is one that is devoid of any detectable microbial life including bacteria, viruses, protozoa and parasites. The GF state is different from gnotobiotic animals where the microbiome is fully described, or ‘specific pathogen free’ (SPF) animals where a moderately normal microbiome is present but devoid of pathogenic microorganisms. Pioneering GF research in poultry in the late 1940s and 1950s has its origin in a need understand the mode of action of antibiotics. Early researchers quickly established that GF chicks responded differently to antibiotics than CV counterparts. The GF experimental model has since been exploited in many divergent fields including pathology, immunology, metabolism, anatomy, physiology, and others. The absence of a microbiome presents the host with a range of advantages and disadvantages. For example, GF chicks often grow more quickly and have lower feed conversion ratio (FCR) than their CV counterparts but may be less resilient to external stress and have a compromised immunological maturation rate. This review will summarize the literature on GF animal research with a special emphasis on poultry. The objective of the review is to establish a frame of reference to understand the extent of the role of the microbiome in animal health, welfare, nutrition, and growth, to provide opportunities for targeted modulation of the microbiome to achieve desired phenotypic responses whilst simultaneously minimizing unintended collateral effects.

Informal nutrition symposium: leveraging the microbiome (and the metabolome) for poultry production

Knowledge of gut microbiology of poultry has advanced from a limited ability to culture relatively few microbial species, to attempting to understand the complex interactions between the bird and its microbiome. The Informal Nutrition Symposium 2021 was intended to help poultry scientists to make sense of the implications of the vast amounts of information being generated by researchers. This paper represents a compilation of the talks given at the symposium by leading international researchers in this field. The symposium began with an overview of the historical developments in the field of intestinal microbiology and microbiome research in poultry. Next, the systemic effects of the microbiome on health in the context of the interplay between the intestinal microbiota and the immune system were presented. Because the microbiome and the host communicate and influence each other, the novel field of kinomics (the study of protein phosphorylation) as used in the study of the poultry microbiome was discussed. Protein phosphorylation is a rapid response to the complex of signals among the microbiome, intestinal lumen metabolites, and the host. Then, a description of why an understanding of the role of microbial endocrinology in poultry production can lead to new understanding of the mechanisms by which the gut microbiota and the host can interact in defined mechanisms that ultimately determine health, pathogenesis of infectious disease, and behavior was given. Finally, a view forward was presented underscoring the importance of understanding mechanisms in microbiomes in other organ systems and other species. Additionally, the importance of the development of new -omics platforms and data management tools to more completely understand host microbiomes was stressed.

Gut Microbiota Implications for Health and Welfare in Farm Animals: A Review

Simple Summary

Farm animal health and welfare have been paid increasing concern in the world, which is generally assessed by the measurements of physical health, immune response, behavior, and physiological indicators, such as stress-related hormone, cortisone, and norepinephrine. Gut microbiota as a “forgotten organ” has been reported for its great influence on the host phenotypes through the immune, neural, and endocrine pathways to affect the host health and behavior. In addition, fecal microbiota transplantation as a novel approach is applied to regulating the composition and function of the recipient farm animals. In this review, we summarized recent studies that gut microbiota influenced health, immunity, behavior, and stress response, as well as the progress of fecal microbiota transplantation in farm animals. The review will provide new insights into the measurement of farm animal health and welfare concerning gut microbiota, and the implication of fecal microbiota transplantation to improve productivity, health, and welfare. Above all, this review suggests that gut microbiota is a promising field to evaluate and improve animal welfare.

Abstract

In the past few decades, farm animal health and welfare have been paid increasing concern worldwide. Farm animal health and welfare are generally assessed by the measurements of physical health, immune response, behavior, and physiological indicators. The gut microbiota has been reported to have a great influence on host phenotypes, possibly via the immune processes, neural functions, and endocrine pathways, thereby influencing host phenotypes. However, there are few reviews regarding farm animals’ health and welfare status concerning the gut microbiota. In this point of view, (1) we reviewed recent studies showing that gut microbiota (higher alpha diversity, beneficial composition, and positive functions) effectively influenced health characteristics, immunity, behaviors, and stress response in farm animals (such as pigs, chickens, and cows), which would provide a novel approach to measure and evaluate the health status and welfare of farm animals. In addition, fecal microbiota transplantation (FMT) as one of the methods can modulate the recipient individual’s gut microbiota to realize the expected phenotype. Further, (2) we highlighted the application of FMT on the improvement of the production performance, the reduction in disease and abnormal behavior, as well as the attenuation of stress in farm animals. It is concluded that the gut microbiota can be scientifically used to assess and improve the welfare of farm animals. Moreover, FMT may be a helpful strategy to reduce abnormal behavior and improve stress adaption, as well as the treatment of disease for farm animals. This review suggests that gut microbiota is a promising field to evaluate and improve animal welfare.

Managing Gut Microbiota through In Ovo Nutrition Influences Early-Life Programming in Broiler Chickens

The chicken gut is the habitat to trillions of microorganisms that affect physiological functions and immune status through metabolic activities and host interaction. Gut microbiota research previously focused on inflammation; however, it is now clear that these microbial communities play an essential role in maintaining normal homeostatic conditions by regulating the immune system. In addition, the microbiota helps reduce and prevent pathogen colonization of the gut via the mechanism of competitive exclusion and the synthesis of bactericidal molecules. Under commercial conditions, newly hatched chicks have access to feed after 36-72 h of hatching due to the hatch window and routine hatchery practices. This delay adversely affects the potential inoculation of the healthy microbiota and impairs the development and maturation of muscle, the immune system, and the gastrointestinal tract (GIT). Modulating the gut microbiota has been proposed as a potential strategy for improving host health and productivity and avoiding undesirable effects on gut health and the immune system. Using early-life programming via in ovo stimulation with probiotics and prebiotics, it may be possible to avoid selected metabolic disorders, poor immunity, and pathogen resistance, which the broiler industry now faces due to commercial hatching and selection pressures imposed by an increasingly demanding market.

Metagenome-assembled genomes and gene catalog from the chicken gut microbiome aid in deciphering antibiotic resistomes

Gut microbial reference genomes and gene catalogs are necessary for understanding the chicken gut microbiome. Here, we assembled 12,339 microbial genomes and constructed a gene catalog consisting of ~16.6 million genes by integrating 799 public chicken gut microbiome samples from ten countries. We found that 893 and 38 metagenome-assembled genomes (MAGs) in our dataset were putative novel species and genera, respectively. In the chicken gut, Lactobacillus aviarius and Lactobacillus crispatus were the most common lactic acid bacteria, and glycoside hydrolases were the most abundant carbohydrate-active enzymes (CAZymes). Antibiotic resistome profiling results indicated that Chinese chicken samples harbored a higher relative abundance but less diversity of antimicrobial resistance genes (ARGs) than European samples. We also proposed the effects of geography and host species on the gut resistome. Our study provides the largest integrated metagenomic dataset from the chicken gut to date and demonstrates its value in exploring chicken gut microbial genes.

Feng et al. include genome recovery and data analysis of large number of chicken gut metagenomic datasets which significantly expands the reference genomes available from the chicken gut microbial communities, and catalog the genes prevalent in the gut systems. They further depict the countryspecific chicken gut antibiotic resistomes and the effects of geography and host species on the gut resistome.

Development and Functional Properties of Intestinal Mucus Layer in Poultry

Intestinal mucus plays important roles in protecting the epithelial surfaces against pathogens, supporting the colonization with commensal bacteria, maintaining an appropriate environment for digestion, as well as facilitating nutrient transport from the lumen to the underlying epithelium. The mucus layer in the poultry gut is produced and preserved by mucin-secreting goblet cells that rapidly develop and mature after hatch as a response to external stimuli including environmental factors, intestinal microbiota as well as dietary factors. The ontogenetic development of goblet cells affects the mucin composition and secretion, causing an alteration in the physicochemical properties of the mucus layer. The intestinal mucus prevents the invasion of pathogens to the epithelium by its antibacterial properties (e.g. β-defensin, lysozyme, avidin and IgA) and creates a physical barrier with the ability to protect the epithelium from pathogens. Mucosal barrier is the first line of innate defense in the gastrointestinal tract. This barrier has a selective permeability that allows small particles and nutrients passing through. The structural components and functional properties of mucins have been reviewed extensively in humans and rodents, but it seems to be neglected in poultry. This review discusses the impact of age on development of goblet cells and their mucus production with relevance for the functional characteristics of mucus layer and its protective mechanism in the chicken’s intestine. Dietary factors directly and indirectly (through modification of the gut bacteria and their metabolic activities) affect goblet cell proliferation and differentiation and can be used to manipulate mucosal integrity and dynamic. However, the mode of action and mechanisms behind these effects need to be studied further. As mucins resist to digestion processes, the sloughed mucins can be utilized by bacteria in the lower part of the gut and are considered as endogenous loss of protein and energy to animal. Hydrothermal processing of poultry feed may reduce this loss by reduction in mucus shedding into the lumen. Given the significance of this loss and the lack of precise data, this matter needs to be carefully investigated in the future and the nutritional strategies reducing this loss have to be defined better.

Research Note: Immunocompetent cells in blood and intestine after administration of Lacto-Immuno-Vital in drinking water of broiler chickens

The understanding of the synbiotics´ impact on the host is incomplete. To improve the knowledge, we study the effect of Lacto-Immuno-Vital synbiotic preparation in chickens on local and systemic immune response by evaluation of immunocompetent cells in the peripheral blood and jejunal mucosa. Hematological method was used for determination of white blood cell count, and flow cytometry for measurement the functions of phagocytes and subpopulation of lymphocytes (CD3, CD4, CD8, IgM, and IgA). Cell Qest programme (Germany) was used for analysing of data obtained from flow cytometer and GraphPad Prism version 4.0 for comparison by paired t test between control and experimental groups. The experiment was conducted in a commercial broiler chicken fattening farm, the birds were handled and sacrificed in a humane manner. A flock of 64,400 one-day-old Hybrid ROSS 308 chickens were included in the 42-d experiment. The chickens were randomly divided into 2 equal groups, experimental and control, and each group of chickens was housed in a different hall while maintaining the same conditions. The chickens in the experimental group (Lactovital) received 500 g of Lacto-Immuno-Vital (Hajduvet Kft., Hungary) in 1,000 L of drinking water. Lacto-Immuno-Vital was administered daily from the first day (D1) to D7 of the experiment. From D 7 to D 22 it was given in a pulsed manner (every third day) at a dose of 300 g in 1,000 L of drinking water. Control group received only the standard diet. For immune analyses 6 randomly chosen chickens from experimental and control group were taken from the halls. The sampling days were set at D 8 and D 22 of the experiment. Samples of peripheral blood were collected from vena subclavia. The chickens were euthanized and whole jejunum was taken during necropsy into Hanks ice solution (pH 7.2–7.3). Administration of Lacto-Immuno-Vital in drinking water of nonstressed broilers during fattening period in commercial production increased phagocytic activity and phagocytic index. The number of IgA+ and CD8+ cells in lamina propria of intestine was decreased in chickens fed diet supplemented with Lacto-Immuno-Vital in drinking water. We suggest that increased phagocytic activity and decreased number of immunocompetent cells in mucosa of intestine was caused by improved systemic and local immune system function.

Macro- and microstructures of the digestive tract in the Eurasian collared dove, Streptopelia decaocto (Frivaldszky 1838): Adaptive interplay between structure and dietary niche

We describe the functional morphology of the digestive tract of the Eurasian collared dove, Streptopelia decaocto using anatomical, morphometric, histological, histochemical, and ultrastructure techniques, and relate our findings to the species' dietary niche. Our results revealed that the esophagus is displaced on both sides of the neck and has highly folded tunica mucosa, which confer greater elasticity for efficient swallowing and passage of food to the crop. The proventriculus is delicate and its mucosal layer contains polymorphic glands with dense profound and superficial secretory units that open to the luminal surface by gastric pores. The ventriculus is biconvex and lined with a keratinized koilin membrane. The tubular glands within the mucosal lining include the isthmus, the neck, and the basal segment that comprise chief and basal cells with prominent nuclei. At the cuticle-mucosal interface, pyramidal vertical rodlets of the cuticle are secreted and superficially covered by a thin film of a horizontal matrix. The mucosa of the ileum form pyramidal villi that are oriented perpendicularly to the central lumen. Enterocytes infiltrated with goblet cells make up the epithelial lining of the villi. There are subtle differences in the thicknesses of corresponding tunics together with histochemical reactions of alcian blue (AB) and Masson-Goldner trichrome (MT) for their microstructures. Overall, our findings reveal remarkable convergence of both macro-and microstructures in S. decaocto to other granivorous species, and offer further evidence of the close association between functional morphology and feeding style relative to food swallowing, digestion, and absorption.

The Absence of Gut Microbiota Alters the Development of the Apicomplexan Parasite Eimeria tenella

Coccidiosis is a widespread intestinal disease of poultry caused by a parasite of the genus Eimeria. Eimeria tenella, is one of the most virulent species that specifically colonizes the caeca, an organ which harbors a rich and complex microbiota. Our objective was to study the impact of the intestinal microbiota on parasite infection and development using an original model of germ-free broilers. We observed that germ-free chickens presented significantly much lower load of oocysts in caecal contents than conventional chickens. This decrease in parasite load was measurable in caecal tissue by RT-qPCR at early time points. Histological analysis revealed the presence of much less first (day 2pi) and second generation schizonts (day 3.5pi) in germ-free chickens than conventional chickens. Indeed, at day 3.5pi, second generation schizonts were respectively immature only in germ-free chickens suggesting a lengthening of the asexual phase of the parasite in the absence of microbiota. Accordingly to the consequence of this lengthening, a delay in specific gamete gene expressions, and a reduction of gamete detection by histological analysis in caeca of germ-free chickens were observed. These differences in parasite load might result from an initial reduction of the excystation efficiency of the parasite in the gut of germ-free chickens. However, as bile salts involved in the excystation step led to an even higher excystation efficiency in germ-free compared to conventional chickens, this result could not explain the difference in parasite load. Interestingly, when we shunted the excystation step in vivo by infecting chickens with sporozoites using the cloacal route of inoculation, parasite invasion was similar in germ-free and in conventional chickens but still resulted in significantly lower parasite load in germ-free chickens at day 7pi. Overall, these data highlighted that the absence of intestinal microbiota alters E. tenella replication. Strategies to modulate the microbiota and/or its metabolites could therefore be an alternative approach to limit the negative impact of coccidiosis in poultry.

Sending signals - The microbiota's contribution to intestinal epithelial homeostasis

The intestine is inhabited by a diverse range of microorganisms, which requires the host to employ numerous barrier measures to prevent bacterial invasion. However, the intestinal microbiota additionally acts symbiotically with host cells to maintain epithelial barrier function, and perturbation to this interaction plays a pivotal role in intestinal pathogenesis. In this review, we highlight current findings of how the intestinal microbiota influences host intestinal epithelial cells. In particular, we review the roles of numerous microbial-derived products as well as mechanisms by which these microbial products influence the regulation of intestinal epithelial population dynamics and barrier function.

Effect of delayed feeding post-hatch on expression of tight junction- and gut barrier-related genes in the small intestine of broiler chickens during neonatal development

The gut not only plays a key role in digestion and absorption of nutrients but also forms a physical barrier and first line of defense between the host and the luminal environment. A functional gut barrier (mucus and epithelial cells with tight junctions [TJ]) is essential for optimal health and efficient production in poultry. In current broiler system, chicks are deprived of food and water up to 72 h due to uneven hatching, hatchery procedures, and transportation. Post-hatch feed delay results in lower BW, higher FCR and mortality, and delayed post-hatch gut development. Little is known about the effects of early neonatal development and delayed feeding immediately post-hatch on gut barrier function in chickens. Therefore, the aim of the present study was to characterize the expression pattern of gut barrier-related and TJ-related genes in the small intestine of broiler chickens during early development and delay in access to feed. Newly hatched chicks received feed and water immediately after hatch or were subjected to 48 h delayed access to feed to mimic commercial hatchery setting and operations. Birds were sampled (n = 6) at -48, 0, 4, 24, 48, 72, 96, 144, 192, 240, 288, and 336 h post-hatch. Jejunum and ileum were collected, cleaned of digesta, and snap-frozen in liquid nitrogen or fixed in paraformaldehyde. The relative mRNA levels of gut barrier- and TJ-related protein genes were measured by quantitative PCR and analyzed by 2-way ANOVA. In both tissues, changes (P < 0.05) in gene expression pattern of gut barrier-related and TJ-related genes were detected due to delayed access to feed post-hatch and/or development. In general, expression of TJ-related genes was downregulated while mRNA levels of gut barrier-related genes were upregulated during development. Histological differences and changes in mucin staining due to age and treatment were observed. These results suggest that delayed access to feed post-hatch may affect TJ structure and/or function and therefore gut barrier function and overall health of the chicken small intestine.

Galactomannan Pentasaccharide Produced from Copra Meal Enhances Tight Junction Integration of Epithelial Tissue through Activation of AMPK

Mannan oligosaccharide (MOS) is well-known as an effective fed supplement for livestock to increase their nutrients absorption and health status. Pentasaccharide of mannan (MOS5) was reported as a molecule that possesses the ability to increase tight junction of epithelial tissue, but the structure and mechanism of action remains undetermined. In this study, the mechanism of action and structure of MOS5 were investigated. T84 cells were cultured and treated with MOS5 compared with vehicle and compound C, a 5′-adenosine monophosphate-activated protein kinase (AMPK) inhibitor. The results demonstrated that the ability of MOS5 to increase tight junction integration was inhibited in the presence of dorsomorphine (compound C). Phosphorylation level of AMPK was elevated in MOS5 treated group as determined by Western blot analysis. Determination of MOS5 structure was performed using enzymatic mapping together with ¹H, ¹³C NMR, and 2D-NMR analysis. The results demonstrated that the structure of MOS5 is a β-(1,4)-mannotetraose with α-(1,6)-galactose attached at the second mannose unit from non-reducing end.

Microbiota, Gut Health and Chicken Productivity: What Is the Connection?

Gut microbiota and its relationship to animal health and productivity in commercial broiler chickens has been difficult to establish due to high variability between flocks, which derives from plenty of environmental, nutritional, and host factors that influence the load of commensal and pathogenic microbes surrounding birds during their growth cycle in the farms. Chicken gut microbiota plays a key role in the maintenance of intestinal health through its ability to modulate host physiological functions required to maintain intestinal homeostasis, mainly through competitive exclusion of detrimental microorganisms and pathogens, preventing colonization and therefore decreasing the expense of energy that birds normally invest in keeping the immune system active against these pathogens. Therefore, a “healthy” intestinal microbiota implies energy saving for the host which translates into an improvement in productive performance of the birds. This review compiles information about the main factors that shape the process of gut microbiota acquisition and maturation, their interactions with chicken immune homeostasis, and the outcome of these interactions on intestinal health and productivity.

Production and purification of mannan oligosaccharide with epithelial tight junction enhancing activity

Background

Mannanan oligosaccharide (MOS) is well-known as effective supplement food for livestock to increase their nutrients absorption and health status, but the structure and identification of bioactive MOS remain unclear. In this study, MOS production was accomplished, using enzymatic hydrolysis of pretreated coconut meal substrate with recombinant mannanase.

Methods

The mannanase gene was cloned from Bacillus subtilis cAE24, then expressed in BL21. Purified Mannanase exhibit stability over a wide range of pH and temperature from pH 6-8 and 4 °C to 70 °C, respectively. SEM analysis revealed that sonication could change the surface characteristic of copra meal, which gave better MOS yield, compared to untreated substrates. The separation and purification of each MOS were achieved using Biogel-P2 column chromatography. Determination of biological active MOS species was also investigated. T84 cells were cultured and treated with each of the purified MOS species to determine their tight junction enhancing activity.

Results

Scanning electron microscope imaging showed that pretreatment using sonication could disrupt the surface of copra meal better than grinding alone, which can improve the production of MOS. Pentamer of MOS (M5) significantly increased tight junction integration of T84 cells measured with TEER (p < 0.0001).

Alterations in gut microflora populations and brush border functionality following intra-amniotic administration (Gallus gallus) of wheat bran prebiotic extracts

Wheat bran is the by-product of milling wheat flour which is one of the richest sources of dietary fiber, and cellulase that can be used for increasing the soluble dietary fiber.

Ingestion of paddy rice increases intestinal mucin secretion and goblet cell number and prevents dextran sodium sulfate-induced intestinal barrier defect in chickens

Paddy rice is a potential feed grain for chickens, whose strong gizzards can crush the hull. Here, we investigated whether paddy rice rich in hull-derived water-insoluble dietary fiber stimulates intestinal mucin secretion and production, as well as the possible involvement of paddy rice in intestinal barrier function. Layer male chicks at 7 d of age were divided into four groups according to the diet: corn, polished rice, brown rice, or paddy rice (650 g/kg diet), which they ate for 14 consecutive days. At 21 d of age, the birds were refed their experimental diets, and small intestinal mucin fractions were collected to determine intestinal mucin content. Small intestinal mucin secretion was induced most strongly in the paddy rice group (Experiment 1). The rank order of diet-induced mucin secretion was paddy rice > corn = brown rice > polished rice. Ileal MUC2 gene expression and ileal number of goblet cells were highest in the paddy rice group (Experiment 1). A study of bromodeoxy-U uptake into ileal epithelial cells indicated the increase in goblet cells in the paddy rice group was related to accelerate epithelial cell migration (Experiment 2). A single supplementation of isolated rice hulls without kernels increased MUC2 gene expression and goblet cell numbers (Experiment 3), suggesting the importance of the hull's bulk-forming capacity on mucin production. Finally, chicks fed corn or paddy rice were orally administered dextran sodium sulfate (DSS) to disrupt intestinal barrier function. In the DSS-treated birds, the intestinal permeability of fluorescein isothiocyanate dextran in the everted gut sacs was much lower in the paddy rice group than in the corn group (Experiment 4), showing that paddy rice protects against mucosal disruption. In conclusion, ingestion of paddy rice increases intestinal mucin secretion and production through enhanced MUC2 gene expression and epithelial turnover and prevents DSS-induced intestinal barrier defects in chickens.

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

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

Host-microbe interaction in the gastrointestinal tract

The gastrointestinal tract is a highly complex organ in which multiple dynamic physiological processes are tightly coordinated while interacting with a dense and extremely diverse microbial population. From establishment in early life, through to host-microbe symbiosis in adulthood, the gut microbiota plays a vital role in our development and health. The effect of the microbiota on gut development and physiology is highlighted by anatomical and functional changes in germ-free mice, affecting the gut epithelium, immune system and enteric nervous system. Microbial colonisation promotes competent innate and acquired mucosal immune systems, epithelial renewal, barrier integrity, and mucosal vascularisation and innervation. Interacting or shared signalling pathways across different physiological systems of the gut could explain how all these changes are coordinated during postnatal colonisation, or after the introduction of microbiota into germ-free models. The application of cell-based in-vitro experimental systems and mathematical modelling can shed light on the molecular and signalling pathways which regulate the development and maintenance of homeostasis in the gut and beyond.

Influence of the Gut Microbiota Composition on Campylobacter jejuni Colonization in Chickens

The Campylobacter jejuni-host interaction may be affected by the host's gut microbiota through competitive exclusion, metabolites, or modification of the immune response. To understand this interaction, C. jejuni colonization and local immune responses were compared in chickens with different gut microbiota compositions. Birds were treated with an antibiotic cocktail (AT) (experiments 1 and 2) or raised under germfree (GF) conditions (experiment 3). At 18 days posthatch (dph), they were orally inoculated either with 10⁴ CFU of C. jejuni or with diluent. Cecal as well as systemic C. jejuni colonization, T- and B-cell numbers in the gut, and gut-associated tissue were compared between the different groups. Significantly higher numbers of CFU of C. jejuni were detected in the cecal contents of AT and GF birds, with higher colonization rates in spleen, liver, and ileum, than in birds with a conventional gut microbiota (P < 0.05). Significant upregulation of T and B lymphocyte numbers was detected in cecum, cecal tonsils, and bursa of Fabricius of AT or GF birds after C. jejuni inoculation compared to the respective controls (P < 0.05). This difference was less clear in birds with a conventional gut microbiota. Histopathological gut lesions were observed only in C. jejuni-inoculated AT and GF birds but not in microbiota-colonized C. jejuni-inoculated hatchmates. These results demonstrate that the gut microbiota may contribute to the control of C. jejuni colonization and prevent lesion development. Further studies are needed to identify key players of the gut microbiota and the mechanisms behind their protective role.

Supplementing the feeds of layer pullets, at different ages with two different fiber sources improves immune function

Two experiments were conducted to study the effects of lignocellulose supplementation on immune function in layer pullets at different stages of growth. Four-wk-old pullets (Experiment 1) were fed a control, diet (Diet C); Diet C plus 1% mixed soluble/insoluble fiber (Diet MF), or plus 1% insoluble fiber (Diet IF). At 7.5 wk-of-age, heterophil phagocytosis, and oxidative burst in Groups MF (328.5 beads/100 cells; 4,330.0 ΔRFU; relative fluorescent units) and IF (350.3; 5,264.4) were greater (P < 0.05) than Controls (303.4; 3,509.0). At 8 wk-of-age, Group MF and IF relative weights of bursa of Fabricius (0.57 g/100 g BW; 0.58 g /100 g BW), thymus glands (0.77; 0.78), and areas of Peyer's patches (PP) (2.7 cm2; 2.9 cm2) were higher (P < 0.05) than Controls (bursa, 0.50 g; thymus, 0.70 g; PP area, 1.8 cm2). In Experiment 2, 10-wk-old pullets were fed a control diet or diets containing 1.5% MF or IF for 8 wk. At 14 wk-of-age IF pullets had higher (P < 0.05) heterophil phagocytosis efficiency (447.9 beads/100 cells) than Controls (376.4) and MF and IF had greater (P < 0.05) oxidative burst (1,302.9 and 1,857.7 ΔRFU) than Controls (744.1). At 17 wk-of-age MF and IF had increased (P < 0.05) proliferation of T-lymphocytes (ConcanavalinA-stimulated) (100.4 and 103.1% of unstimulated cells) and B-lymphocytes (lipopolysaccharide-stimulated) (122.4 and 129.0) than Controls (ConA, 79.4; lipopolysaccharide, 106.6). At 18 wk-of-age, IF pullets were heavier (1,607.5 g, P < 0.05) than Controls (1,506.5 g), had heavier (P < 0.05) bursa of Fabricius (1.12 g) than MF and Control groups (0.98 g; 0.92 g) and cecal tonsils of MF (0.38 g) and IF (0.39 g) weighted more (P < 0.05) than Controls (0.33 g). Number of jejunal and ileal PP (10.0) in IF pullets was higher (P < 0.05) than Controls (7.1). These results indicate that both MF and IF can improve development of the immune system of young and grower pullets during periods of maturation and involution of lymphoid organs.

Oral imazalil exposure induces gut microbiota dysbiosis and colonic inflammation in mice

The fungicide imazalil (IMZ) is used extensively in vegetable and fruit plantations and as a post-harvest treatment to avoid rot. Here, we revealed that ingestion of 25, 50 and 100 mg IMZ kg(-1) body weight for 28 d induced gut microbiota dysbiosis and colonic inflammation in mice. The relative abundance of Bacteroidetes, Firmicutes and Actinobacteria in the cecal contents decreased significantly after exposure to 100 mg kg(-1) IMZ for 28 d. In feces, the relative abundance in Bacteroidetes, Firmicutes and Actinobacteria decreased significantly after being exposed to 100 mg kg(-1) IMZ for 1, 14 and 7 d, respectively. High throughput sequencing of the V3-V4 region of the bacterial 16S rRNA gene revealed a significant reduction in the richness and diversity of microbiota in cecal contents and feces of IMZ-treated mice. Operational taxonomic units (OTUs) analysis identified 49.3% of OTUs changed in cecal contents, while 55.6% of OTUs changed in the feces after IMZ exposure. Overall, at the phylum level, the relative abundance of Firmicutes, Proteobacteria and Actinobacteria increased and that of Bacteroidetes decreased in IMZ-treated groups. At the genus level, the abundance of Lactobacillus and Bifidobacterium decreased while those of Deltaproteobacteria and Desulfovibrio increased in response to IMZ exposure. In addition, it was observed that IMZ exposure could induce colonic inflammation characterized by infiltration of inflammatory cells, elevated levels of lipocalin-2 (lcn-2) in the feces, and increased mRNA levels of Tnf-α, IL-1β, IL-22 and IFN-γ in the colon. Our findings strongly suggest that ingestion of IMZ has some risks to human health.

Degenerative primer design and gene sequencing validation for select turkey genes

We successfully designed and validated degenerative primers for turkey genes MUC2, RPS13, TBP and TFF2 based on chicken sequences in order to use gene transcription analysis to evaluate (quantify) the mucin transcription to probiotic supplementation in turkeys. Primers were designed for the genes MUC2, TFF2, RPS13 and TBP using a degenerative primer design method based on the available Gallus gallus sequences. All primer sets, which produced a single PCR amplicon of the expected sizes, were cloned into the TOPO(®) vector and then transformed into TOP 10(®) competent cells. Plasmid DNA isolation was performed on the TOP10(®) cell culture and sent for sequencing. Sequences were analyzed using NCBI BLAST. All genes sequenced had over 90% homology with both the chicken and predicted turkey sequences. The sequences were used to design new 100% homologous primer sets for the genes of interest.

Early intestinal development and mucin transcription in the young poult with probiotic and mannan oligosaccharide prebiotic supplementation

Alternative and adjunctive approaches to decreasing the use of dietary antibiotics are becoming popular areas of study. Supplemental probiotics (commensal microbes) and prebiotics (indigestible complex carbohydrates) are 2 dietary approaches to facilitating the intestinal colonization of beneficial bacteria to compete with potential pathogens, thus creating a healthy mucosal environment. The intestinal mucosa is composed of mucin glycoproteins, which play a key role in preventing the attachment of pathogenic bacteria. At hatch, the neonatal turkey intestine is relatively aseptic and vulnderable to bacterial colonization by both commensal and pathogenic microbes. In the current study, we determined the transcription of MUC2, the primary mucin protein produced by goblet cells within the small intestine, and we also measured intestinal morphology immediately post-hatch through d 11. Poults were fed a conventional starter diet, the starter diet supplemented with one of 2 commercial probiotics (A, B), or a commercial mannan oligosaccharide. MUC2 transcription increased from d zero to d 4 post-hatch (P< 0.05), but there was no effect of probiotic or prebiotic supplementation. Villus height and villus area both increased with Probiotic B and mannan oligosaccharide supplementation (P<0.05) and there was a significant d X treatment interaction effect for crypt depth (P=0.007). These results suggest that probiotic and prebiotic supplementation can positively alter the intestinal microenvironment.

Evaluation of yeast dietary supplementation in broilers challenged or not with Salmonella on growth performance, cecal microbiota composition and Salmonella in ceca, cloacae and carcass skin

The dietary supplementation of Saccharomyces cerevisiae var. boulardii was evaluated in broilers challenged or not challenged with Salmonella Enteritidis (SE) using a 2 × 2 factorial arrangement. Depending on yeast inclusion at 0 (C) or 1 × 10⁹ cfu/kg diet (Y) and SE challenge (0 or log 6.3 cfu/bird) on d 15, the experiment had four treatments C, Y, C-SE, and Y-SE, respectively. Each treatment had seven replicate floor pens with 15 broilers. Growth performance responses were determined weekly and overall for the 5 week experimental period. Salmonella levels and prevalence in ceca, cloacae, and carcass skin were determined by culture procedures, while cecal microbiota was determined by real time PCR. Yeast supplementation had no effect (PY > 0.05) on growth performance. For the overall post SE-challenge period (i.e., wk 3 to wk 5), Salmonella reduced body weight gain (BWG) (PSE < 0.001), feed intake (FI) (PSE = 0.032), and the European production efficiency (EPEF) factor (PSE = 0.005). Broilers Y-SE had higher (P < 0.001) overall BW gain compared to C-SE ones. Overall mortality was 2.14% and did not differ (P > 0.05) between treatments. Reduced Salmonella levels in the cloacae (P = 0.014) and on the breast skin (P = 0.006) and lower prevalence on the neck skin (P = 0.007) were noted for treatment Y-SE compared to C-SE. Yeast supplementation did not have an effect (P > 0.05) on cecal microbiota composition at d 1 and d 21 post SE-challenge. On the contrary, SE-challenge reduced cecal levels of total bacteria (PSE = 0.002), E. coli (PSE = 0.006), Bifidobacterium spp. (PSE = 0.006), Bacteroides spp. (PSE = 0.010), and Clostridial populations belonging to cluster I and cluster XIVa, (PSE = 0.047 and PSE = 0.001, respectively) on d 1 post SE-challenge. At 21 d post SE-challenge, only the levels of cecal Lactobacillus spp. (PSE = 0.001) and Bifidobacterium spp. (PSE = 0.049) were reduced compared to the non SE-challenged groups. In conclusion, yeast supplementation in SE challenged broilers (Y-SE) was beneficial for growth performance and reduced Salmonella presence compared to C-SE ones. The disturbance of cecal microbiota balance by SE merits further investigation for potential implications in gut and overall bird health.

Effect of lactulose supplementation on growth performance, intestinal histomorphology, cecal microbial population, and short-chain fatty acid composition of broiler chickens

This study investigated the effects of dietary lactulose supplementation on broiler growth performance, intestinal histomorphology, cecal microflora, and cecal short-chain fatty acid (SCFA) concentrations. A total of 245 one-day-old male broiler chickens were randomly assigned to 5 different treatments, with 7 replicates including 7 birds each. The birds received the same basal diet based on corn--soybean meal, and lactulose was included in the diet at 0, 0.2, 0.4, 0.6, or 0.8% at the expense of corn and/or soybean meal. The body weight gain (linear, P=0.027) and feed conversion (linear, P=0.003) from 0 to 21 d showed significant improvement as dietary lactulose was increased from 0.2 to 0.8%. However, dietary lactulose did not affect broiler performance at the end of the experiment (42 d). Furthermore, intestinal measurements and the goblet cell count of broilers fed a lactulose-containing diet differed from those of birds fed a diet that did not contain lactulose. In addition, a significant quadratic response in the Lactobacillus count (P≤0.001) was observed at 42 d on increasing the level of lactulose. The cecal coliform bacterial population was not affected by the dietary treatments. Supplementation with lactulose significantly increased the concentrations of acetate, propionate, butyrate, and total SCFA measured on d 7 and d 42. In conclusion, inclusion of lactulose in the diet can enhance broiler performance and intestinal morphology by selectively stimulating intestinal microflora and increasing cecal SCFA concentrations.

Early intestinal growth and development in poultry

While there are many accepted "facts" within the field of poultry science that are in truth still open for discussion, there is little debate with respect to the tremendous genetic progress that has been made with commercial broilers and turkeys (Havenstein et al., 2003, 2007). When one considers the changes in carcass development in poultry meat strains, these genetic "improvements" have not always been accompanied by correlated changes in other physiological systems and this can predispose some birds to developmental anomalies (i.e. ascites; Pavlidis et al., 2007; Wideman et al., 2013). Over the last decade, there has been increased interest in intestinal growth/health as poultry nutritionists have attempted to adopt new approaches to deal with the broader changes in the overall nutrition landscape. This landscape includes not only the aforementioned genetic changes but also a raft of governmental policies that have focused attention on the environment (phosphorus and nitrogen excretion), consumer pressure on the use of antibiotics, and renewable biofuels with its consequent effects on ingredient costs. Intestinal morphology has become a common research tool for assessing nutritional effects on the intestine but it is only one metric among many that can be used and histological results can often be interpreted in a variety of ways. This study will address the broader body of research on intestinal growth and development in commercial poultry and will attempt to integrate the topics of the intestinal: microbial interface and the role of the intestine as an immune tissue under the broad umbrella of intestinal physiology.