Interplay of poultry-microbiome interactions - influencing factors and microbes in poultry infections and metabolic disorders

1. The poultry microbiome and its stability at every point in time, either free range or reared under different farming systems, is affected by several environmental and innate factors. The interaction of the poultry birds with their microbiome, as well as several inherent and extraneous factors contribute to the microbiome dynamics. A poor understanding of this could worsen poultry heath and result in disease/metabolic disorders.2. Many diseased states associated with poultry have been linked to dysbiosis state, where the microbiome experiences some perturbation. Dysbiosis itself is too often downplayed; however, it is considered a disease which could lead to more serious conditions in poultry. The management of interconnected factors by conventional and emerging technologies (sequencing, nanotechnology, robotics, 3D mini-guts) could prove to be indispensable in ensuring poultry health and welfare.3. Findings showed that high-throughput technological advancements enhanced scientific insights into emerging trends surrounding the poultry gut microbiome and ecosystem, the dysbiotic condition, and the dynamic roles of intrinsic and exogenous factors in determining poultry health. Yet, a combination of conventional, -omics based and other techniques further enhance characterisation of key poultry microbiome actors, their mechanisms of action, and roles in maintaining gut homoeostasis and health, in a bid to avert metabolic disorders and infections.4. In conclusion, there is an important interplay of innate, environmental, abiotic and biotic factors impacting on poultry gut microbiome homoeostasis, dysbiosis, and overall health. Associated infections and metabolic disorders can result from the interconnected nature of these factors. Emerging concepts (interkingdom or network signalling and neurotransmitter), and future technologies (mini-gut models, cobots) need to include these interactions to ensure accurate control and outcomes.

Site-Directed Mutagenesis: Improving the Acid Resistance and Thermostability of Bacillus velezensis α-Amylase and Its Preliminary Feed Application

The current study aimed to improve the acid resistance and thermostability of Bacillus velezensis α-amylase through site-directed mutagenesis, with a specific focus on its applicability to the feed industry. Four mutation sites, P546E, H572D, A614E, and K622E, were designed in the C domain of α-amylase, and three mutants, Mut1 (E), Mut2 (ED), and Mut3 (EDEE), were produced. The results showed that the specific activity of Mut3 was 50 U/mg higher than the original α-amylase (Ori) after incubation at 40 °C for 4 h. Compared to Ori, the acid resistance of Mut3 showed a twofold increase in specific activity at pH 2.0. Moreover, the results of preliminary feed hydrolysis were compared between Ori and Mut3 by designing three factors, three levels of orthogonal experiment for enzymatic hydrolysis time, feed quantity, and amount of amylase. It was observed that the enzymatic hydrolysis time and feed quantity showed an extremely significant difference (p < 0.01) in Mut3 compared to Ori. However, the amount of enzyme showed significant (p < 0.05) improvement in the enzymatic hydrolysis in Mut3 as compared to Ori. The study identified Mut3 as a promising candidate for the application of α-amylase in the feed industry.

Effect of emulsifier on growth performance, nutrient digestibility, intestinal morphology, faecal microbiology and blood biochemistry of broiler chickens fed low-energy diets

BACKGROUND

This study hypothesizes that a natural multicomponent emulsifier (Lipidol) could improve production performance in broiler chickens by aiding lipid digestion and addressing digestive system limitations.

OBJECTIVES

The study aimed to investigate the effects of dietary emulsifier inclusion on the growth performance, nutrient digestibility, intestinal morphology, faecal microbiology, blood biochemistry and liver enzyme activities of broiler chickens fed low-energy diets.

METHODS

The experiment involved 144 one-day-old male broiler chickens split into 4 treatments. Four diets were used: standard metabolizable energy (ME) as a control diet and three low-ME diets, reducing by 100 kcal/kg by adding 0.5, 1 and 1.5 g/kg of exogenous emulsifier (Em).

RESULTS

No significant differences were observed in body weight gain and feed intake. However, during the finisher period (25-42 days), supplementation emulsifier to low-ME diets notably improved feed efficiency. Although crude protein, organic matter and ash digestibility remained unaffected, dry matter (DM) digestibility significantly increased in broilers fed low-ME diets with emulsifier. Broilers receiving 0.5 g/kg of emulsifier showed the highest villus width and surface area values. Moreover, including 1.5 g/kg of emulsifier led to the highest villus height to crypt depth ratio. Faecal microbiota, blood biochemistry and liver enzyme activities showed no significant differences.

CONCLUSIONS

Emulsifier supplementation compensated for the energy reduction and enhanced performance, DM digestibility and some intestinal morphology parameters in broiler chickens fed low-ME diet. Using 0.5 g/kg of emulsifier per 100 kcal of ME reduction in broiler diets is suggested.

Growth and response to Escherichia coli lipopolysaccharide challenge in Lohmann LSL-Lite pullets when fed a source of omega-3 fatty acids and yeast bioactives from hatch through to 16 wk of age

Growth and response to Escherichia coli lipopolysaccharide (LPS) challenge in Lohmann LSL-Lite pullets when fed a source of omega-3 fatty acids (n-3 FA) and yeast bioactives (YB) from hatch through to 16 wk of age (woa) were investigated. Co-extruded full fat flaxseed and pulse mixture (FFF; 1:1 wt/wt) supplied n-3 FA and YB were yeast cell walls processed with β-1,3-glucan hydrolase. A total of 1,064-day-old pullets were placed in cages (19 birds/cage) and allocated to 7 diets (n = 8). The iso-caloric and iso-nitrogenous diets were control, control + 1, 3, or 5% FFF and + 0.025, 0.05, or 0.1% YB. The birds had ad libitum access to feed and water. Body weight (BW), feed intake, and lymphoid organs weight were recorded. At 15 woa, 2 pairs of pullets/cage received intravenous injection of either 1 mL of sterile saline without or with 8 mg LPS/kg BW. Injected pullets were bled, monitored for BW and cloaca temperature at time points within 168 h. Birds fed 1% FFF were heavier (P < 0.04) than birds fed other diets at 16 woa with FFF and YB exhibiting non-linear responses. Control birds had heavier (P = 0.02) thymus at 4 woa. Spleen weight increased quadratically (P < 0.05) in response to FFF at 8 and YB at 16 woa. The LPS increased cloaca temperature and altered concentration of several plasma metabolites (P < 0.05). The interaction (P < 0.05) between LPS and diet was such that control birds exhibited lower creatine kinase (CK) upon challenge with LPS relative to birds fed other diets. The LPS birds fed 1% FFF and 0.05% YB showed higher plasma albumin than non-LPS cohorts. Non-LPS birds fed control, 1 and 3% FFF had higher plasma K than LPS cohorts. In general, FFF and YB exhibited linear and quadratic effects (P < 0.05) on select plasma metabolites. In conclusion, dietary provision of n-3 FA and YB influenced pullet BW at sexual maturity, development of lymphoid organs and modulated some plasma metabolites in response to LPS.

Genetic engineering of complex feed enzymes into barley seed for direct utilization in animal feedstuff

Currently, feed enzymes are primarily obtained through fermentation of fungi, bacteria, and other microorganisms. Although the manufacturing technology for feed enzymes has evolved rapidly, the activities of these enzymes decline during the granulating process and the cost of application has increased over time. An alternative approach is the use of genetically modified plants containing complex feed enzymes for direct utilization in animal feedstuff. We co-expressed three commonly used feed enzymes (phytase, β-glucanase, and xylanase) in barley seeds using the Agrobacterium-mediated transformation method and generated a new barley germplasm. The results showed that these enzymes were stable and had no effect on the development of the seeds. Supplementation of the basal diet of laying hens with only 8% of enzyme-containing seeds decreased the quantities of indigestible carbohydrates, improved the availability of phosphorus, and reduced the impact of animal production on the environment to an extent similar to directly adding exogenous enzymes to the feed. Feeding enzyme-containing seeds to layers significantly increased the strength of the eggshell and the weight of the eggs by 10.0%-11.3% and 5.6%-7.7% respectively. The intestinal microbiota obtained from layers fed with enzyme-containing seeds was altered compared to controls and was dominated by Alispes and Rikenella. Therefore, the transgenic barley seeds produced in this study can be used as an ideal feedstuff for use in animal feed.

Supplementation with paraformic acid in the diet improved intestinal development through modulating intestinal inflammation and microbiota in broiler chickens

The aim of this study was to explore the effects of supplementing paraformic acid (PFA) to the diet of broiler chickens on intestinal development, inflammation, and microbiota. A total of 378 healthy 1-day-old Arbor Acres broilers with similar birth weight were used in this study, and randomly assigned into two treatment groups. The broiler chickens were received a basal diet or a basal diet supplemented with 1,000 mg/kg PFA. Results showed that PFA supplementation increased (P &lt; 0.05) small intestinal villus height and villus height/crypt depth ratio, elevated intestinal mucosal factors (mucin 2, trefoil factor family, and zonula occludens-1) concentrations, and upregulated mNRA expression of y + L amino acid transporter 1. Moreover, PFA supplementation decreased (P &lt; 0.05) the concentrations of inflammatory cytokines (tumor necrosis factor-alpha, interleukin-1beta, interleukin-6, and interleukin-10), activities of caspase-3 and caspase-8, and mNRA expressions of Toll-like Receptor 4, nuclear factor-kappa B, Bax, and Bax/Bcl-2 ratio in small intestinal mucosa. Dietary PFA supplementation also increased (P &lt; 0.05) alpha diversity of cecal microbiota and relative abundance of Alistipes. The present study demonstrated that supplementation of 1,000 mg/kg PFA showed beneficial effects in improving intestinal development, which might be attributed to the suppression of intestinal inflammation and change of gut microbiota composition in broiler chickens. These findings will aid in our knowledge of the mechanisms through which dietary PFA modulates gut development, as well as support the use of PFA in poultry industry.

Tannic Acid Extracted from Galla chinensis Supplementation in the Diet Improves Intestinal Development through Suppressing Inflammatory Responses via Blockage of NF-κB in Broiler Chickens

The objective of this study was to investigate the effects of adding tannic acid (TA) extracted from Galla chinensis to the diet of broiler chickens on intestinal development. A total of 324 healthy 1-day-old broilers were used in a 42 d study, and divided into two treatment groups at random (six replicates per group). Broilers were either received a basal diet or a basal diet supplemented with 300 mg/kg microencapsulated TA extracted from Galla chinensis. The results showed that dietary supplemented with 300 mg/kg TA from Galla chinensis improved intestinal morphology, promoted intestinal mucosal barrier integrity, and elevated mucosal expressions of nutrients transporters and tight junction protein CLDN3 in broilers. Besides, 300 mg/kg TA from Galla chinensis supplementation decreased the concentrations of inflammatory cytokines in serum and intestinal mucosa and reduced the mRNA expression of NF-κB in intestinal mucosa. Above all, supplementation of 300 mg/kg microencapsulated TA extracted from Galla chinensis showed beneficial effects in improving intestinal development, which might be attributed to the suppression of inflammatory responses via blockage of NF-κB in broiler chickens. These findings will support the use of TA sourced from Galla chinensis in poultry industry.

Effects of dietary palygorskite supplementation on the growth performance, oxidative status, immune function, intestinal barrier and cecal microbial community of broilers

The present study aimed to investigate the effects of palygorskite (PAL) as an alternative to antibiotic on the growth performance, oxidative status, immune function, intestinal barrier and cecal microbial community of broilers. A total of 360 1-day-old male Ross-308 broilers were randomly allotted to three treatments with eight replicates. Broilers in the three groups were designated as follows: basal diet (CON group), basal diet+50 mg/kg chlorotetracycline (ANT group), and basal diet+ 10 g/kg PAL (PAL group). Supplementing PAL reduced feed to gain ratio in broilers during 22 to 42 days of age (P &lt; 0.05), with its value being similar to that of the ANT group (P &gt; 0.05). Broilers fed a PAL-supplemented diet exerted decreased contents of interferon-γ (IFN-γ) and interleukin-1β in serum, and the same reduction was found in jejunal IFN-γ level, when compared to the CON group (P &lt; 0.05). Moreover, compared with the CON group, broilers after PAL treatment had a lower malondialdehyde content in jejunal mucosa (P &lt; 0.05). Supplementing PAL elevated jejunal villus height (VH) and ratio of VH to crypt depth compared with the ANT group (P &lt; 0.05). Cecal microbiota communities among the three groups were significant different, as demonstrated by distinct clusters from partial least squares discriminant analysis, although dietary treatments had no significant effects on the bacterial richness and diversity indices (P &gt; 0.05). At genus level, the addition of PAL increased the relative abundance of norank_f__Barnesiellaceae and decreased that of unclassified_f__Oscillospiraceae in cecal digesta compared with those in the CON group (P &lt; 0.05); the proportion of genus norank_f__Barnesiellaceae was increased by PAL treatment when compared with the ANT group (P &lt; 0.05). Moreover, spearman's correlations showed that the modulation of cecal microflora composition by PAL supplementation was closely correlated with the promotion of growth performance (feed to gain ratio) and intestinal health-related (contents of malondialdehyde and IFN-γ, and VH value in jejunum) variables of broilers (P &lt; 0.05). Taken together, dietary PAL could improve the growth performance, antioxidant capacity, and immune status, as well as intestinal barrier function in broilers, which might be partially associated with the alteration of cecal microbiota. Moreover, dietary PAL may be a promising alternative to antibiotic growth promoter for broilers.

Impact of Feeding Postbiotics and Paraprobiotics Produced From Lactiplantibacillus plantarum on Colon Mucosa Microbiota in Broiler Chickens

This study was conducted to evaluate the impact of feeding postbiotics and paraprobiotics produced from Lactiplantibacillus plantarum on colon mucosa microbiota in broiler chickens. In this study, 336 one-day-old COBB 500 chicks were randomly allotted to eight treatment groups and replicated six times with seven birds per replicate. The treatment included T1 (Negative control) = Basal diet, T2 (Positive control) = Basal diet + 0.01% oxytetracycline, T3 = Basal diet + 0.2% postbiotic TL1, T4 = Basal diet + 0.2% postbiotic RS5, T5 = Basal diet + 0.2% paraprobiotic RG11, T6 = Basal diet + 0.2% postbiotic RI11, T7 = Basal diet + 0.2% paraprobiotic RG14, and T8 = Basal diet + 0.2% paraprobiotic RI11. There were reported changes in the bacterial community using 16S rRNA sequencing of the colon mucosa. The results of the sequencing of 16S rRNA genes in the colon mucosa samples indicated that compared to birds fed the negative control diet, birds fed paraprobiotic RI11 diets were recorded to have a lower relative abundance of Proteobacteria, while those fed the positive control were recorded to have a higher proportion of Firmicutes. Also, lower Enterococcus was reported in paraprobiotic RI11, while the most abundant genus was Bacteroides in postbiotic TL1. This study revealed that supplementation of postbiotics and paraprobiotics in the diets of broilers demonstrated positive effects on the microbiota by supporting the increase of beneficial microbes like the Firmicutes while decreasing harmful microbes like the Proteobacteria. Therefore, this study has provided knowledge on the modification of chicken mucosa microbiota through the feeding of postbiotics and paraprobiotics.

Potential Replacements for Antibiotic Growth Promoters in Poultry: Interactions at the Gut Level and Their Impact on Host Immunity

The chicken gastrointestinal tract (GIT) has a complex, biodiverse microbial community of ~ 9 million bacterial genes plus archaea and fungi that links the host diet to its health. This microbial population contributes to host physiology through metabolite signaling while also providing local and systemic nutrients to multiple organ systems. In a homeostatic state, the host-microbial interaction is symbiotic; however, physiological issues are associated with dysregulated microbiota. Manipulating the microbiota is a therapeutic option, and the concept of adding beneficial bacteria to the intestine has led to probiotic and prebiotic development. The gut microbiome is readily changeable by diet, antibiotics, pathogenic infections, and host- and environmental-dependent events. The intestine performs key roles of nutrient absorption, tolerance of beneficial microbiota, yet responding to undesirable microbes or microbial products and preventing translocation to sterile body compartments. During homeostasis, the immune system is actively preventing or modulating the response to known or innocuous antigens. Manipulating the microbiota through nutrition, modulating host immunity, preventing pathogen colonization, or improving intestinal barrier function has led to novel methods to prevent disease, but also resulted in improved body weight, feed conversion, and carcass yield in poultry. This review highlights the importance of adding different feed additives to the diets of poultry in order to manipulate and enhance health and productivity of flocks.

Glucose Oligosaccharide and Long-Chain Glucomannan Feed Additives Induce Enhanced Activation of Intraepithelial NK Cells and Relative Abundance of Commensal Lactic Acid Bacteria in Broiler Chickens

Restrictions on the use of antibiotics in the poultry industry stimulate the development of alternative nutritional solutions to maintain or improve poultry health. This requires more insight in the modulatory effects of feed additives on the immune system and microbiota composition. Compounds known to influence the innate immune system and microbiota composition were selected and screened in vitro, in ovo, and in vivo. Among all compounds, 57 enhanced NK cell activation, 56 increased phagocytosis, and 22 increased NO production of the macrophage cell line HD11 in vitro. Based on these results, availability and regulatory status, six compounds were selected for further analysis. None of these compounds showed negative effects on growth, hatchability, and feed conversion in in ovo and in vivo studies. Based on the most interesting numerical results and highest future potential feasibility, two compounds were analyzed further. Administration of glucose oligosaccharide and long-chain glucomannan in vivo both enhanced activation of intraepithelial NK cells and led to increased relative abundance of lactic acid bacteria (LAB) amongst ileum and ceca microbiota after seven days of supplementation. Positive correlations between NK cell subsets and activation, and relative abundance of LAB suggest the involvement of microbiota in the modulation of the function of intraepithelial NK cells. This study identifies glucose oligosaccharide and long-chain glucomannan supplementation as effective nutritional strategies to modulate the intestinal microbiota composition and strengthen the intraepithelial innate immune system.

Bacillus subtilis PB6 based probiotic supplementation plays a role in the recovery after the necrotic enteritis challenge

In poultry production, birds are raised under intensive conditions, which can enable rapid spread of infections, with Clostridium perfringens-caused necrotic enteritis (NE) being one of the most devastating for the industry. The current investigation was conducted to evaluate the effectiveness of Bacillus subtilis PB6 probiotic supplementation on bird’s post NE recovery, based on chicken performance, cecal microbiota composition, ileum histomorphometric measurements, and short-chain fatty acid production in the cecum of the birds that were challenged with NE mid-production. Birds were split into four groups, including a negative control, positive control challenged with C. perfringens, group supplemented with B. subtilis probiotic, and NE challenged birds supplemented with B. subtilis probiotic. Following NE challenge birds were allowed to reach the end of production time at 40 days, and samples were collected to estimate if probiotic supplementation resulted in better post-NE recovery. Intestinal lesion score across the duodenum, jejunum, and ileum indicated that at the end of production timeline NE challenged birds supplemented with B. subtilis probiotic had lower intestinal lesion scores compared to NE challenged birds without probiotic supplementation implying improved recovery. Probiotic supplementation improved performance of NE challenged birds only in the post-NE recovery stage. NE challenged birds had a significant increase in cecal propionic acid, which was not observed in NE challenged birds supplemented with B.subtilus. Both B. subtilis supplemented groups (challenged and unchanged) were characterized by a significant rise in cecal acetic and butyric acid. Our results demonstrate that B. subtilis supplementation can assist the birds in dealing with NE outbreak and long term recovery.

The use of random forests modelling to detect yeast-mannan sensitive bacterial changes in the broiler cecum

In this study, sequencing of the 16S rRNA gene targeting the V4-V6 regions was conducted to assess the cecal microbial alterations in response to dietary supplementation with a yeast derived mannan rich fraction (MRF) in standard commercial broiler production settings across four separate broiler trials. The resulting data was analysed to identify consistent changes in the bacterial community structure of the broiler cecum in response to MRF supplementation. Subsequently, the datasets from each individual trial were pooled and analysed for differences between control and MRF supplemented diets at day 35 posthatch. The results from this analysis showed that Phylum Firmicutes was decreased and Phylum Bacteroidetes was increased across all four trials at day 35 posthatch when compared to the control. An extension of the random forest bioinformatics approach to discover a highly relevant set of microbial operational taxonomic units (OTUs) which are indicative of MRF supplementation in the broiler cecum was then used. This approach has enabled the identification of a novel set of yeast-mannan sensitive bacterial OTUs in the cecal microbiome. This information will be helpful in developing potential future nutritional strategies and will be favourable to the poultry industry.

A Review of Prebiotics Against Salmonella in Poultry: Current and Future Potential for Microbiome Research Applications

Prebiotics are typically fermentable feed additives that can directly or indirectly support a healthy intestinal microbiota. Prebiotics have gained increasing attention in the poultry industry as wariness toward antibiotic use has grown in the face of foodborne pathogen drug resistance. Their potential as feed additives to improve growth, promote beneficial gastrointestinal microbiota, and reduce human-associated pathogens, has been well documented. However, their mechanisms remain relatively unknown. Prebiotics increasing short chain fatty acid (SCFA) production in the cecum have long since been considered a potential source for pathogen reduction. It has been previously concluded that prebiotics can improve the safety of poultry products by promoting the overall health and well-being of the bird as well as provide for an intestinal environment that is unfavorable for foodborne pathogens such as Salmonella. To better understand the precise benefit conferred by several prebiotics, "omic" technologies have been suggested and utilized. The data acquired from emerging technologies of microbiomics and metabolomics may be able to generate a more comprehensive detailed understanding of the microbiota and metabolome in the poultry gastrointestinal tract. This understanding, in turn, may allow for improved administration and optimization of prebiotics to prevent foodborne illness as well as elucidate unknown mechanisms of prebiotic actions. This review explores the use of prebiotics in poultry, their impact on gut Salmonella populations, and how utilization of next-generation technologies can elucidate the underlying mechanisms of prebiotics as feed additives.