Week-Old Chicks with High Bacteroides Abundance Have Increased Short-Chain Fatty Acids and Reduced Markers of Gut Inflammation

Multiple Enzymes Expressed by the Gut Microbiota Can Transform Typhaneoside and Are Associated with Improving Hyperlipidemia

The mechanism of multiple enzymes mediated drug metabolism in gut microbiota is still unclear. This study explores multiple enzyme interaction process of typhactyloside (TYP) with gut microbiota and its lipid-lowering pharmacological activity. TYP, with bioavailability of only 2.78%, is an active component of Typha angustifolia L. and Pushen capsules which is clinically treated for hyperlipidemia. The metabolic process of TYP is identified, and key enzymes involved in TYP metabolism are validated through gene knockout and overexpression techniques. Through overexpressing α-rhamnosidase (Rha) in Escherichia coli, TYP is verified to metabolize into isorhamnetin-3-O-neohesperidin (M1) and isorhamnetin-3-O-glucoside (M2) after removing rhamnose through Rha. Besides, knockout of β-glucosidase (Glu) confirms that TYP generates M3 through Glu after removing glucose. Combined with molecular docking, M3 is transformed to generate 3,4-dihydroxyphenylacetic acid (M4), protocatechuic acid (M5), and 3-hydroxyphenylacetic acid (M6) through flavonoid reductase (Flr) and chalcone isomerase (Chi). In conclusion, multiple enzymes involved in TYP metabolism (Rha/Glu→Flr→Chi) are identified. Through in vivo experiments, combined use of M3 and M5 also shows excellent anti-hyperlipidemia efficacy. This is the first study on complex metabolism mechanism and pharmacological activity of natural flavonoids mediated by multiple enzymes, which provide insight to investigate analogous natural products.

Exploring the Mechanism of Clostridium autoethanogenum Protein for Broiler Growth Based on Gut Microbiota and Serum Metabolomics

Intestinal health is vital for poultry production, and protein plays a key role in intestinal nutrition. The present study used 16S rRNA gene sequencing and serum metabolomics to investigate the effect of CAP on the cecal microflora structure and serum metabolites in 42-day-old broiler chickens. A total of 480 one-day-old Arbor Acres broiler chickens were randomly divided into four treatments with twelve replicates comprising 10 chickens each, evenly divided by sex. The four groups were basal diet group (CAP0), treatment group 1 (CAP2), treatment group 2 (CAP3), and treatment group 3 (CAP4). The broilers in the CAP0 group were fed a basal diet (without CAP), while those in the CAP2, CAP3, and CAP4 groups received diets containing 2%, 3%, and 4% CAP, respectively. Growth performance results showed that dietary CAP supplementation significantly ameliorated the feed conversion rate (FCR) of broilers at 42 days in the CAP3 and CAP4 groups (p < 0.05). Microbial results revealed that CAP did not alter the dominant microorganisms in the cecum at the phylum, family, and genus levels. LEfSe analysis showed significantly higher relative abundances of p_Desulfobacterota, f_Desulfovibrionaceae, and g_Ruminococcus in the CAP3 group compared to the CAP0 and CAP4 groups. Metabolomic analyses indicated that the effect of incorporating CAP into the diet on serum metabolites primarily focused on organic acids and their derivatives, small peptides, amino acid derivatives, and oxidized lipids. The addition of 3% or 4% CAP to the diet can enhance metabolic pathways such as the citrate cycle (TCA cycle) and arginine and proline metabolism. In summary, incorporating CAP into the diet can increase the relative abundance of beneficial bacteria in the cecum and improve the feed conversion efficiency of broilers by enhancing amino acid and energy metabolism.

Metabolic modelling uncovers the complex interplay between fungal probiotics, poultry microbiomes, and diet

BACKGROUND

The search for alternatives to antibiotic growth promoters in poultry production has increased interest in probiotics. However, the complexity of the interactions between probiotics, gut microbiome, and the host hinders the development of effective probiotic interventions. This study explores metabolic modelling to examine the possibility of designing informed probiotic interventions within poultry production.

RESULTS

Genomic metabolic models of fungi were generated and simulated in the context of poultry gut microbial communities. The modelling approach correlated with short-chain fatty acid production, particularly in the caecum. Introducing fungi to poultry microbiomes resulted in strain-specific and diet-dependent effects on the gut microbiome. The impact of fungal probiotics on microbiome diversity and pathogen inhibition varied depending on the specific strain, resident microbiome composition, and host diet. This context-dependency highlights the need for tailored probiotic interventions that consider the unique characteristics of each poultry production environment.

CONCLUSIONS

This study demonstrates the potential of metabolic modelling to elucidate the complex interactions between probiotics, the gut microbiome, and diet in poultry. While the effects of specific fungal strains were found to be context-dependent, the approach itself provides a valuable tool for designing targeted probiotic interventions. By considering the specific characteristics of the host microbiome and dietary factors, this methodology could guide the deployment of effective probiotics in poultry production. However, the current work relies on computational predictions, and further in vivo validation studies are needed to confirm the efficacy of the identified probiotic candidates. Nonetheless, this study represents a significant step in using metabolic models to inform probiotic interventions in the poultry industry. Video Abstract.

In ovo sodium butyrate administration differentially impacts growth performance, intestinal barrier function, immune response, and gut microbiota characteristics in low and high hatch-weight broilers

BACKGROUND

Hatch weight (HW) affects broiler growth and low HW (LHW) often leads to suboptimal performance. Sodium butyrate (SB) has been shown to promote growth through enhanced intestinal health. This study investigated how broilers with different HW responded to in ovo SB injection and whether SB could enhance gut health and performance in LHW chicks. Ross 308 broiler eggs were injected on incubation d 12 with physiological saline (control) or SB at 0.1% (SB1), 0.3% (SB3), or 0.5% (SB5). Post-hatch, male chicks from each treatment were categorized as high HW (HHW) or LHW and assigned to 8 groups in a 4 × 2 factorial design. Production parameters were recorded periodically. Intestinal weight, length, and gene expression related to gut barrier function and immune response were examined on d 14 and 42. Cecal microbiota dynamics and predicted functionality were analyzed using 16S rRNA gene sequencing.

RESULTS

SB treatments did not affect hatchability. HHW-control group exhibited consistently better weight gain and FCR than LHW-control group. SB dose-dependently influenced performance and gut health in both HW categories, with greater effects in LHW broilers at 0.3%. LHW-SB3 group attained highest body weight on d 42, exceeding controls but not significantly differing from HHW-SB3 group. LHW-SB3 group showed upregulation of gut-barrier genes CLDN1 in ileum, TJP1 in jejunum and anti-inflammatory cytokine IL-10 in both jejunum and ileum on d 14. Additionally, LHW-SB3 group upregulated mucin-producing MUC6 gene in ileum, while HHW-SB5 group increased pro-inflammatory IL-12p40 cytokine in caecum on d 42. LHW-SB3 group demonstrated shorter relative intestinal lengths, while HHW-SB5 had longer lengths. HHW-control group had higher bacterial diversity and growth-promoting bacteria while LHW-control group harbored the potential pathogen Helicobacter. SB reshaped gut microbiota biodiversity, composition, and predicted metabolic pathways in both HW categories. The LHW-SB3 group exhibited highest alpha diversity on d 14 and most beneficial bacteria at all timepoints. HHW-SB5 group presented increased pathogenic Escherichia-Shigella and Campylobacter on d 42.

CONCLUSIONS

HW significantly affects subsequent performance and SB has differential effects based on HW. LHW chicks benefited more from 0.3% SB, showing improvements in growth, intestinal development, health, and gut microbiota characteristics.

Dynamic Shifts in Antibiotic Residues and Gut Microbiome Following Tilmicosin Administration to Silkie Chickens

Tilmicosin, an antibiotic widely used in animal husbandry to prevent and treat bacterial infections, raises concerns due to its residual accumulation, which impacts both animal health and food safety. In this study, we conducted a comprehensive analysis of tilmicosin clearance patterns in different tissues, assessed physiological impacts through blood biochemistry, and investigated changes in gut microbial composition with 16S rRNA sequencing of the tilmicosin-treated Silkie chickens. Initially, we observed rapid peaks in tilmicosin residues in all tissues within 1 day after treatment, but complete metabolism took longer, extending beyond 9 days. Moreover, tilmicosin treatment significantly decreased serum levels of total bile acid, blood urea nitrogen, and uric acid, while increasing the levels of direct bilirubin, total bilirubin, and glutathione peroxidase at day 3, followed by a decrease from day 5 onwards. The effects of tilmicosin use on microbial composition and diversity lasted for an extended period, with the relative abundance of Proteobacteria remaining significantly different between the control and tilmicosin-treated groups at 120 days. Additionally, correlation analysis revealed a strong positive correlation between Mucispirillum_schaedleri and tilmicosin residue in all tissues, while Parabbacteroide_distasonis, Faecalibacterium_prausnitzii, and others exhibited negative correlations with tilmicosin residue. Overall, our study indicates a significant correlation between intestinal microbes and antibiotic residues, providing a theoretical basis for guiding the withdrawal period after antibiotic use.

Dose-Dependent Effects of Turmeric (Curcuma aromatica S.) Starch on Colonic Fermentation in Rats

Background; Turmeric starch (TS) has gained significant attention due to its potential health benefits. Rich in resistant starch (RS) and higher in phosphorus, TS is anticipated to possess properties of high-phosphorus-type RS. Objectives; To understand the host physiology of TS, this study investigated the dose-dependent effects of TS on colonic fermentation in rats. Methods; Four experimental diets containing different levels of TS (5%, 10%, and 20% w/w) were formulated and fed to male Fischer 344 rats for two weeks and compared with rats fed a 0% TS diet (TS0). Results; Results showed that increasing the dose of TS resulted in reduced body weight gain, lower visceral tissue weight, and increased cecal mucin and IgA levels compared with the TS0 group. Further, fecal dry weight increased dose-dependently parallel to the starch excretion rate. Higher doses of TS resulted in increased short chain fatty acid (SCFA) production, specifically cecal acetate content, as well as in a dose-dependent decrease in the cecal pH level. However, this study did not observe a positive effect of TS on colonic alkaline phosphatase (ALP) activity, and the impact on small intestinal ALP activity remains unclear. Notably, beneficial bacteria such as the family Oscillospiraceae, genus Lachnospiraceae NK4A136 group, and Ruminococcus spp. were found to have been enriched in the TS-fed groups, further supporting the beneficial effects of TS on gut microbiota and SCFA production. Additionally, the genus Mucispirillum, which is known to possess beneficial and opportunistic pathogenic traits under immunocompromised states, was found in the TS-fed groups. Conclusions; According to these results, it is clear that TS served as a prebiotic substrate in rats, with a notable modulation of the microbial composition.

Effects of adding antibiotics to an inactivated oil-adjuvant avian influenza vaccine on vaccine characteristics and chick health

During poultry immunization, antibiotics are typically added to inactivated oil-adjuvant avian influenza (AI) vaccines. Here, we evaluated the effects of adding ceftiofur, a third-generation cephalosporin, to an AI vaccine on vaccine stability and structure and on chick growth, immune efficacy, blood concentrations, biochemical and immunological indices, and gut microbiota. The results demonstrated that neither aqueous ceftiofur sodium nor ceftiofur hydrochloride oil emulsion formed a stable mixture with the vaccine. Adding ceftiofur formulations, particularly ceftiofur hydrochloride, at >4% significantly destabilized the vaccine's water-in-oil structures. Adding ceftiofur also increased vaccine malabsorption at the injection site; specifically, adding ceftiofur hydrochloride reduced H5N8 and H7N9 antibody titers after the first immunization (P < 0.05) and H7N9 antibody titers after the second immunization (P < 0.01). Serum drug concentrations did not differ significantly between the groups with ceftiofur sodium and hydrochloride addition. Ceftiofur addition increased postvaccination chick weight loss; compared with the vaccine alone, ceftiofur sodium-vaccine mixture increased chick weight significantly (P < 0.05). Ceftiofur addition also increased stress indices and reduced antioxidant capacity significantly (P < 0.05 or P < 0.01). Vaccination-related immune stress reduced gut microbiota diversity in chicks; ceftiofur addition reversed this change. AI vaccine immunization significantly reduced the relative abundance of Lactobacillus and Muribaculaceae but significantly increased that of Bacteroides and Eubacterium coprostanoligenes group. Ceftiofur addition restored the gut microbiota structure; in particular, ceftiofur hydrochloride addition significantly increased the abundance of the harmful gut microbes Escherichia-Shigella and Enterococcus, whereas ceftiofur sodium addition significantly reduced it. The changes in gut microbiota led to alterations in metabolic pathways related to membrane transport, amino acids, and carbohydrates. In conclusion, adding ceftiofur to the AI vaccine had positive effects on chick growth and gut microbiota modulation; however, different antibiotic concentrations and formulations may disrupt vaccine structure, possibly affecting vaccine safety and immunization efficacy. Thus, the addition of antibiotics to oil-adjuvant vaccines is associated with a risk of immunization failure and should be applied to poultry with caution.

Eucalyptus essential oil exerted a sedative-hypnotic effect by influencing brain neurotransmitters and gut microbes via the gut microbiota-brain axis

Sleep disorders are becoming more and more common, leading to many health problems. However, most of current available medications to treat sleep disorders are addictive and even impair cognitive abilities. Therefore, it is important to find a natural and safe alternative to treat sleep disorders. In this study, twenty-four 8-week-old male ICR mice (25 ± 2 g) were equally divided into three groups: the control group (gavage of 0.9% saline), the eucalyptus essential oil (EEO) group (10 mg/kg B.W.), and the diazepam group (1 mg/kg B.W.). Firstly, open field test and sleep induction test were used to determine the sedative-hypnotic effect of EEO. Secondly, the effect of EEO on neurotransmitters in the mice brain was determined. Finally, based on the gut microbiota-brain axis (GMBA), the effect of EEO on the intestinal flora of mice was explored. It was found that EEO significantly reduce the activity and prolong the sleep duration of mice, exhibiting a good sedative-hypnotic effect. In the brain, EEO could increase the levels of sleep-promoting neurotransmitters, such as glutamine, Gamma-aminobutyric acid (GABA), glycine, tryptophan, N-acetylserotonin, and 5-hydroxyindoleacetic acid (5-HIAA). In the intestine, EEO was found to increase the diversity of gut microbes, the abundance of short chain fatty acid (SCFA) producing flora, and the abundance of functional flora synthesizing GABA and glycine neurotransmitters. These studies suggested that EEO exerted a sedative-hypnotic effect by acting on gut microbes and neurotransmitters in the brain. EEO has the potential to become a natural and safe alternative to traditional hypnotic sedative drugs.

Unravelling the role of gut microbiota in acute pancreatitis: integrating Mendelian randomization with a nested case-control study

Background

Gut microbiota may influence the development of acute pancreatitis (AP), a serious gastrointestinal disease with high morbidity and mortality. This study aimed to identify a causal link by investigating the relationship between gut microbiota and AP.

Methods

Mendelian randomization (MR) and a nested case-control study were used to explore associations between gut microbiota composition and AP. 16S rRNA sequencing, random forest modelling (RF), support vector machine (SVM), and Kaplan-Meier survival analysis was applied to identify significant gut microbiota and their correlation with hospitalization duration in AP patients.

Results

Bidirectional MR results confirmed a causal link between specific gut microbiota and AP (15 and 8 microbial taxa identified via forward and reverse MR, respectively). The 16S rRNA sequencing analysis demonstrated a pronounced difference in gut microbiota composition between cases and controls. Notably, after a comprehensive evaluation of the results of RF and SVM, Bacteroides plebeius (B. plebeius) was found to play a significant role in influencing the hospital status. Using a receiver operating characteristic (ROC) curve, the predictive power (0.757) of B. plebeius. Kaplan-Meier survival analysis offered further insight that patients with an elevated abundance of B. plebeius experienced prolonged hospital stays.

Conclusion

Combining MR with nested case-control studies provided a detailed characterization of interactions between gut microbiota and AP. B. plebeius was identified as a significant contributor, suggesting its role as both a precursor and consequence of AP dynamics. The findings highlight the multifactorial nature of AP and its complex relationship with the gut microbiota. This study lays the groundwork for future therapeutic interventions targeting microbial dynamics in AP treatment.

Comparative analysis of reproductive tract microbiomes in modern and slower-growing broiler breeder lines

Introduction

The reproductive tract microbiome in hens is of interest because bacteria in the reproductive tract could potentially affect fertilization and egg production, as well as integrate into the forming egg and vertically transmit to progeny.

Methods

The reproductive tract microbiome of 37-week-old modern commercial Cobb breeding dams was compared with that of dams from a broiler Legacy line which has not undergone selection since 1986. All animals were kept together under the same management protocol from day of hatch to avoid confounders.

Results

In regards to reproductive abilities, Cobb dams' eggs weighed more and the magnum section of their reproductive tract was longer. In regards to microbiome composition, it was found that the reproductive tract microbiomes of the two lines had a lot in common but also that the two breeds have unique reproductive tract microbiomes. Specifically, the order Pseudomonadales was higher in the magnum of Legacy dams, while Verrucomicrobiales was lower. In the infundibulum, Lactobacillales were higher in the Legacy dams while Verrucomicrobiales, Bacteroidales, RF32 and YS2 were lower.

Discussion

our results show that breeding programs have modified not only the physiology of the reproductive tract but also the reproductive tract microbiome. Additional research is required to understand the implications of these changes in the reproductive tract microbiome on the chicken host.

Broiler Chicken Cecal Microbiome and Poultry Farming Productivity: A Meta-Analysis

The cecal microbial community plays an important role in chicken growth and development via effective feed conversion and essential metabolite production. The aim of this study was to define the microbial community's variants in chickens' ceca and to explore the most significant association between the microbiome compositions and poultry farming productivity. The meta-analysis included original data from 8 control broiler chicken groups fed with a standard basic diet and 32 experimental groups supplemented with various feed additives. Standard Illumina 16S-RNA gene sequencing technology was used to characterize the chicken cecal microbiome. Zootechnical data sets integrated with the European Production Effectiveness Factor (EPEF) were collected. Analysis of the bacterial taxa abundance and co-occurrence in chicken cecal microbiomes revealed two alternative patterns: Bacteroidota-dominated with decreased alpha biodiversity; and Bacillota-enriched, which included the Actinomycetota, Cyanobacteriota and Thermodesulfobacteriota phyla members, with increased biodiversity indices. Bacillota-enriched microbiome groups showed elevated total feed intake (especially due to the starter feed intake) and final body weight, and high EPEF values, while Bacteroidota-dominated microbiomes were negatively associated with poultry farming productivity. The meta-analysis results lay the basis for the development of chicken growth-promoting feed supplementations, aimed at the stimulation of beneficial and inhibition of harmful bacterial patterns, where relevant metagenomic data can be a tool for their control and selection.

Deciphering the nutritional strategies for polysaccharides effects on intestinal barrier in broilers: Selectively promote microbial ecosystems

The gut microbiota, a complex and dynamic microbial ecosystem, plays a crucial role in regulating the intestinal barrier. Polysaccharide foraging is specifically dedicated to establishing and maintaining microbial communities, contributing to the shaping of the intestinal ecosystem and ultimately enhancing the integrity of the intestinal barrier. The utilization and regulation of individual polysaccharides often rely on distinct gut-colonizing bacteria. The products of their metabolism not only benefit the formation of the ecosystem but also facilitate cross-feeding partnerships. In this review, we elucidate the mechanisms by which specific bacteria degrade polysaccharides, and how polysaccharide metabolism shapes the microbial ecosystem through cross-feeding. Furthermore, we explore how selectively promoting microbial ecosystems and their metabolites contributes to improvements in the integrity of the intestinal barrier.

In vitro digestion and fecal fermentation of selenocompounds: impact on gut microbiota, antioxidant activity, and short-chain fatty acids

Selenium bioavailability is critically influenced by gut microbiota, yet the interaction dynamics with selenocompounds remain unexplored. Our study found that L-Selenomethionine (SeMet) and Se-(Methyl)seleno-L-cysteine (MeSeCys) maintained stability during in vitro gastrointestinal digestion. In contrast, Selenite and L-Selenocystine (SeCys2) were degraded by approximately 13% and 35%. Intriguingly, gut microflora transformed MeSeCys, SeCys2, and Selenite into SeMet. Moreover, when SeCys2 and Selenite incubated with gut microbiota, they produced red selenium nanoparticles with diameters ranging between 100 and 400 nm and boosted glutathione peroxidase activity. These changes were positively associated with an increased relative abundance of unclassified_g__Blautia (Family Lachnospiraceae), Erysipelotrichaceae_UCG-003 (Family Erysipelatoclostridiaceae), and uncultured_bacterium_g__Subdoligranulum (Family Ruminococcaceae). Our findings implied that differential microbial sensitivities to selenocompounds, potentially attributable to their distinct mechanisms governing selenium uptake, storage, utilization, and excretion.

Live black soldier fly (Hermetia illucens) larvae in feed for laying hens: effects on hen gut microbiota and behavior

This study examined the effects of including live black soldier fly (BSF, Hermetia illucens) larvae in the diet of laying hens on gut microbiota, and the association between microbiota and fearfulness. A total of 40 Bovans White laying hens were individually housed and fed 1 of 4 dietary treatments that provided 0, 10, 20%, or ad libitum daily dietary portions of live BSF larvae for 12 wk. Cecum microbiota was collected at the end of the experiment and sequenced. Behavioral fear responses to novel objects and open field tests on the same hens were compared against results from gut microbiota analyses. The results showed that the bacteria genera Enterococcus, Parabacteroides, and Ruminococcus torques group were positively associated with increased dietary portion of live larvae, while Lactobacillus, Faecalibacterium, Bifidobacterium, Subdoligranulum, and Butyricicoccus were negatively associated with larvae in the diet. Inclusion of larvae did not affect fear behavior, but the relative abundance of Lachnospiraceae CHKCI001 and Erysipelatoclostridium was associated with fear-related behaviors. Further studies are needed to determine whether the change in gut microbiota affects fearfulness in the long-term.

Investigating the cecal microbiota of broilers raised in extensive and intensive production systems

Intensive broiler production practices are structured to prevent the introduction and spread of pathogens; however, they can potentially minimize the exposure of broilers to beneficial commensal bacteria. In this study, we used 16S rRNA amplicon sequencing to characterize the cecal microbiota of 35-day-old broilers from 22 independent commercial farms rearing broilers under intensive (IPS) or extensive production systems (EPS). We aimed to determine which bacteria are normal inhabitants of the broiler ceca and which bacteria might be missing from broilers in IPS. In addition, we generated a collection of 410 bacterial isolates, including 87 different species, to be used as a resource to further explore the effects of selected isolates on bird physiology and to elucidate the role of individual species within the cecal microbial community. Our results indicated significant differences in the microbiota of broilers between systems: the microbiota of broilers from EPS was dominated by Bacteroidetes {55.2% ± 8.9 [mean ± standard deviation (SD)]}, whereas Firmicutes dominated the microbiota of broilers from IPS (61.7% ± 14.4, mean ± SD). Bacterial taxa found to be core in the EPS microbiota, including Olsenella, Alistipes, Bacteroides, Barnesiella, Parabacteroides, Megamonas, and Parasutterella, were shown to be infrequent or absent from the IPS microbiota, and the EPS microbiota presented higher phylogenetic diversity and greater predicted functional potential than that of broilers in IPS. The bacteria shown to be depleted in broilers from IPS should be further investigated for their effects on bird physiology and potential application as next-generation probiotics. IMPORTANCE Production practices in intensive farming systems significantly reduce the introduction and spread of pathogens; however, they may potentially minimize the exposure of animals to beneficial commensal microorganisms. In this study, we identified core bacteria from the cecal microbiota of broilers raised in extensive production systems that are missing or reduced in birds from intensive systems, including Olsenella, Alistipes, Bacteroides, Barnesiella, Parabacteroides, Megamonas, and Parasutterella. Furthermore, the cecal microbiota of broilers from extensive systems showed higher diversity and greater functional potential than that of broilers from intensive systems. In addition, a collection of bacterial isolates containing 87 different species was generated from the current study, and this important resource can be used to further explore the role of selected commensal bacteria on the microbial community and bird physiology.

Prophylactic influences of prebiotics on gut microbiome and immune response of heat-stressed broiler chickens

Climatic changes and elevated ambient temperature are significant environmental stressors with a negative impact on birds' physiological, immunological, and behavioral status, increasing their susceptibility to stressors and immunosuppression and consequently increasing intestinal permeability (leaky gut). Prebiotics have been utilized to stop or diminish the harmful effects of stress in chickens. We aimed to evaluate the role of mannan-oligosaccharides, and beta-D-glucan prebiotics supplements in drinking water against experimentally induced heat stress (HS) on broiler chickens and study their impact on birds' performance, gut microbiome, and immune response. A total of 120 1-day-old Ross broiler chicks were allocated into four groups (30 birds/group), and each group was subdivided into triplicates (10 birds each). The experimental groups were classified as follows; the 1st (G1) control birds, the 2nd (G2) birds exposed experimentally to HS, the 3rd (G3) birds administered prebiotics in drinking water without exposure to HS, and the 4th (G4) birds exposed to HS and administered prebiotics in drinking water. After each vaccination, blood samples and serum samples were collected to evaluate the birds' immune status. Fecal samples were also collected for the molecular evaluation of the gut microbiome based on the genetic analyses and sequencing of 16S rRNA gene. The results showed that HS has reduced the birds' performance and badly affected the birds' immune response and gut microbiome. However, the addition of prebiotics to drinking water, with or without stress, enhanced the growth rate, maintained a normal gut microbiome, and improved immune parameters. Moreover, the usage of prebiotics improved the chicken gut microbiome and alleviated the negative effect of heat stress. Administering prebiotics significantly (p < 0.05) increased the relative abundance of beneficial bacteria and eradicated pathogenic ones in the birds' gut microbiome. Prebiotics showed a positive effect on the gut microbiome and the immune status of chickens under HS in addition to their efficacy as a growth promoter.

Cecal Microbiota Development and Physiological Responses of Broilers Following Early Life Microbial Inoculation Using Different Delivery Methods and Microbial Sources

Broilers in intensive systems may lack commensal microbes that have coevolved with chickens in nature. This study evaluated the effects of microbial inocula and delivery methods applied to day-old chicks on the development of the cecal microbiota. Specifically, chicks were inoculated with cecal contents or microbial cultures, and the efficacies of three delivery methods (oral gavage, spraying inoculum into the bedding, and cohousing) were evaluated. Also, a competitive study evaluated the colonization ability of bacteria sourced from extensive or intensive poultry production systems. The microbiota of inoculated birds presented higher phylogenetic diversity values (PD) and higher relative abundance values of Bacteroidetes, compared with a control. Additionally, a reduction in the ileal villus height/crypt depth ratio and increased cecal IL-6, IL-10, propionate, and valerate concentrations were observed in birds that were inoculated with cecal contents. Across the experiments, the chicks in the control groups presented higher relative abundance values of Escherichia/Shigella than did the inoculated birds. Specific microbes from intensively or extensively raised chickens were able to colonize the ceca, and inocula from intensive production systems promoted higher relative abundance values of Escherichia/Shigella. We concluded that Alistipes, Bacteroides, Barnesiella, Mediterranea, Parabacteroides, Megamonas, and Phascolarctobacterium are effective colonizers of the broiler ceca. In addition, oral gavage, spray, and cohousing can be used as delivery methods for microbial transplantation, as indicated by their effects on the cecal microbiota, intestinal morphology, short-chain fatty acids concentration, and cytokine/chemokine levels. These findings will guide future research on the development of next-generation probiotics that are able to colonize and persist in the chicken intestinal tract after a single exposure. IMPORTANCE The strict biosecurity procedures employed in the poultry industry may inadvertently hinder the transmission of beneficial commensal bacteria that chickens would encounter in natural environments. This research aims at identifying bacteria that can colonize and persist in the chicken gut after a single exposure. We evaluated different microbial inocula that were obtained from healthy adult chicken donors as well as three delivery methods for their effects on microbiota composition and bird physiology. In addition, we conducted a competitive assay to test the colonization abilities of bacteria sourced from intensively versus extensively raised chickens. Our results indicated that some bacteria are consistently increased in birds that are exposed to microbial inoculations. These bacteria can be isolated and employed in future research on the development of next-generation probiotics that contain species that are highly adapted to the chicken gut.