Host pathways for recognition: Establishing gastrointestinal microbiota as relevant in animal health and nutrition

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.

Lactic acid bacteria in Asian fermented foods and their beneficial roles in human health

Fermented foods have been a staple in human diets for thousands of years, garnering attention for their health and medicinal benefits. Rich in lactic acid bacteria (LAB) with probiotic properties, these foods play a crucial role in positively impacting the host's gut microbiome composition and overall health. With a long history of safe consumption, fermented foods effectively deliver LAB to humans. Intake of LAB from fermented foods offers three main benefits: (1) enhancing digestive function and managing chronic gastrointestinal conditions, (2) modulating the immune system and offering anti-inflammatory effects to prevent immune-related diseases, and (3) synthesizing vitamins and various bioactive compounds to improve human health. In this review, we highlighted the diverse LAB present in Asian fermented foods and emphasized LAB-rich fermented foods as a natural and effective solution for health enhancement and disease prevention.

Microbiome composition as a potential predictor of longevity in rabbits

BACKGROUND

Longevity and resilience are two fundamental traits for more sustainable livestock production. These traits are closely related, as resilient animals tend to have longer lifespans. An interesting criterion for increasing longevity in rabbit could be based on the information provided by its gut microbiome. The gut microbiome is essential for regulating health and plays crucial roles in the development of the immune system. The aim of this research was to investigate if animals with different longevities have different microbial profiles. We sequenced the 16S rRNA gene from soft faeces from 95 does. First, we compared two maternal rabbit lines with different longevities; a standard longevity maternal line (A) and a maternal line (LP) that was founded based on longevity criteria: females with a minimum of 25 parities with an average prolificacy per parity of 9 or more. Second, we compared the gut microbiota of two groups of animals from line LP with different longevities: females that died/were culled with two parities or less (LLP) and females with more than 15 parities (HLP).

RESULTS

Differences in alpha and beta diversity were observed between lines A and LP, and a partial least square discriminant analysis (PLS-DA) showed a high prediction accuracy (> 91%) of classification of animals to line A versus LP (146 amplicon sequence variants (ASV)). The PLS-DA also showed a high prediction accuracy (> 94%) to classify animals to the LLP and HLP groups (53 ASV). Interestingly, some of the most important taxa identified in the PLS-DA were common to both comparisons (Akkermansia, Christensenellaceae R-7, Uncultured Eubacteriaceae, among others) and have been reported to be related to resilience and longevity.

CONCLUSIONS

Our results indicate that the first parity gut microbiome profile differs between the two rabbit maternal lines (A and LP) and, to a lesser extent, between animals of line LP with different longevities (LLP and HLP). Several genera were able to discriminate animals from the two lines and animals with different longevities, which shows that the gut microbiome could be used as a predictive factor for longevity, or as a selection criterion for these traits.

Dietary supplementation with Lactiplantibacillus plantarum P-8 improves the growth performance and gut microbiota of weaned piglets

Weaning is a stressful event in the pig life cycle. We hypothesized that probiotics could be potential alternatives to antibiotics for promoting growth and ameliorating stress in weaning piglets via gut microbiota modulation and, thus, investigated the beneficial effects of dietary probiotic supplementation in weaning pigs. Ninety weaning piglets (Landrace × large white, 45 males and 45 females, 25 days of age) were randomized into three dietary treatments (30 piglets/treatment, divided into five replicates/treatment, i.e., six piglets/replicate) in this 28-day trial: control (C group, basal diet); probiotic [lactic acid bacteria (LAB) group, basal diet plus Lactiplantibacillus plantarum P-8]; and antibiotic (A group; basal diet plus chlortetracycline). The piglets' growth performance [average daily gain, average daily feed intake (ADFI), and feed conversion ratio (FCR)], immune and antioxidant markers, ileal mucosal morphology, and ileal and colonic microbiomes were compared among treatment groups. Compared to the C and A groups, probiotic supplementation significantly decreased the ADFI, FCR, and ileal mucosal crypt depth while increasing the villus height-to-crypt depth ratio, hepatic glutathione peroxidase and catalase activities, and serum levels of interleukin-2. Both probiotic and antibiotic treatments modulated the piglets' gut microbiomes, with more L. plantarum in the LAB group and more Eubacterium rectale and Limosilactobacillus reuteri in the A group. Probiotic supplementation significantly increased the relative abundance of genes encoding the acetylene, galactose, and stachyose degradation pathways, potentially enhancing nutrient absorption, energy acquisition, and growth performance. Probiotics are effective alternatives to antibiotics for promoting the health of piglets, possibly via gut microbiome modulation.IMPORTANCEWeaning impacts piglet health, performance, and mortality. Antibiotic treatment during weaning can mitigate the negative effects on growth. However, antibiotic use in livestock production contributes to the emergence of antibiotic resistance, which is a threat to global public health. This comprehensive study describes the gut microbial composition and growth performance of weaned piglets after dietary supplementation with Lactiplantibacillus plantarum P-8 or antibiotics. L. plantarum P-8 ameliorated stress and improved antioxidant capacity and growth performance in weaned piglets, accompanied by gut microbiota improvement. L. plantarum P-8 is an effective substitute for antibiotics to promote the health of weaned piglets while avoiding the global concern of drug resistance.

Gut microbiota-derived ursodeoxycholic acid alleviates low birth weight-induced colonic inflammation by enhancing M2 macrophage polarization

BACKGROUND

Low birth weight (LBW) is associated with intestinal inflammation and dysbiosis after birth. However, the underlying mechanism remains largely unknown.

OBJECTIVE

In the present study, we aimed to investigate the metabolism, therapeutic potential, and mechanisms of action of bile acids (BAs) in LBW-induced intestinal inflammation in a piglet model.

METHODS

The fecal microbiome and BA profile between LBW and normal birth weight (NBW) neonatal piglets were compared. Fecal microbiota transplantation (FMT) was employed to further confirm the linkage between microbial BA metabolism and intestinal inflammation. The therapeutic potential of ursodeoxycholic acid (UDCA), a highly differentially abundant BA between LBW and NBW piglets, in alleviating colonic inflammation was evaluated in both LBW piglets, an LBW-FMT mice model, and a DSS-induced colitis mouse model. The underlying cellular and molecular mechanisms by which UDCA suppresses intestinal inflammation were also investigated in both DSS-treated mice and a macrophage cell line. Microbiomes were analyzed by using 16S ribosomal RNA sequencing. Fecal and intestinal BA profiles were measured by using targeted BA metabolomics. Levels of farnesoid X receptor (FXR) were knocked down in J774A.1 cells with small interfering RNAs.

RESULTS

We show a significant difference in both the fecal microbiome and BA profiles between LBW and normal birth weight animals in a piglet model. Transplantation of the microbiota of LBW piglets to antibiotic-treated mice leads to intestinal inflammation. Importantly, oral administration of UDCA, a major BA diminished in the intestinal tract of LBW piglets, markedly alleviates intestinal inflammation in LBW piglets, an LBW-FMT mice model, and a mouse model of colitis by inducing M2 macrophage polarization. Mechanistically, UDCA reduces inflammatory cytokine production by engaging BA receptor FXR while suppressing NF-κB activation in macrophages.

CONCLUSIONS

These findings establish a causal relationship between LBW-associated intestinal abnormalities and dysbiosis, suggesting that restoring intestinal health and postnatal maldevelopment of LBW infants may be achieved by targeting intestinal microbiota and BA metabolism. Video Abstract.

Electrochemical (Bio)Sensing Devices for Human-Microbiome-Related Biomarkers

The study of the human microbiome is a multidisciplinary area ranging from the field of technology to that of personalized medicine. The possibility of using microbiota biomarkers to improve the diagnosis and monitoring of diseases (e.g., cancer), health conditions (e.g., obesity) or relevant processes (e.g., aging) has raised great expectations, also in the field of bioelectroanalytical chemistry. The well-known advantages of electrochemical biosensors-high sensitivity, fast response, and the possibility of miniaturization, together with the potential for new nanomaterials to improve their design and performance-position them as unique tools to provide a better understanding of the entities of the human microbiome and raise the prospect of huge and important developments in the coming years. This review article compiles recent applications of electrochemical (bio)sensors for monitoring microbial metabolites and disease biomarkers related to different types of human microbiome, with a special focus on the gastrointestinal microbiome. Examples of electrochemical devices applied to real samples are critically discussed, as well as challenges to be faced and where future developments are expected to go.

Effects of Dietary Protein Restriction on Colonic Microbiota of Finishing Pigs

This study is aimed at the effects of low-protein diets with four amino acids balanced on serum biochemical parameters and colonic microflora of finishing pigs. Fifty-four healthy (Duroc × Landrace × Yorkshire) hybrid barrows with an average body weight of 70.12 ± 4.03 kg were randomly assigned to one of three dietary treatments with three barrows per pen and six pens per treatment. The barrows were fed a normal protein diet (NP), a low-protein diet (LP), and a very low-protein diet (VLP). Compared with the NP diet, reduced dietary protein did not influence serum biochemical parameters (p > 0.05). The valeric acid was significantly increased with the VLP diet (p < 0.05). Compared with the NP diets, the abundance of Terrisporobacter (13.37%) Clostridium_sensu_stricto_1 (23.37%) and Turicibacter (2.57%) increased to 21.04, 33.42 and 13.68% in LP diets and 16.72, 43.71 and 14.61% in VLP diets, while the abundance of Lactobacillus (9.30%) and Streptococcus (25.26%) decreased to 3.57 and 14.50% in LP diets and 1.86 and 4.07% in VLP diets. Turicibacter and Clostridium_sensu_stricto_6 had a powerful negative correlation with the content of valeric acid (p < 0.01), while Peptococcus and Clostridia_UCG-014 had a very solid positive correlation (p < 0.01). In conclusion, reducing dietary protein level can improve colon microbiota composition, especially reducing the abundance of bacteria related to nitrogen metabolism, but has no significant effect on SCFA except valeric acid. In addition, reduction in the dietary protein level by 5.48% had more different flora than that of 2.74% reduction in dietary CP level.

Probiotic Supplementation and Micronutrient Status in Healthy Subjects: A Systematic Review of Clinical Trials

Micronutrient deficiencies are a worldwide public health concern. Emerging evidence supports the ability of probiotics to enhance micronutrient status, which could aid in the prevention of non-communicable disease-associated malnutrition. This systematic review evaluated evidence of the efficacy of probiotic supplementation to improve micronutrient status in healthy subjects. The authors searched for published English language peer-reviewed journal articles in PubMed, Scopus, Embase, and Google Scholar databases from inception to July 2020 using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The quality of eligible studies was assessed using the Revised Cochrane Risk-of-Bias tool (RoB)2 and Risk of Bias in Non-Randomized Studies of Interventions tool (ROBINS-I tool). Fourteen original studies out of 2790 met the inclusion criteria. The results indicated that, despite varying degrees of efficacy, the intake of certain probiotics in healthy subjects was associated with a positive impact on the status of certain micronutrients (vitamin B12, calcium, folate, iron and zinc). A limitation was that studies were widely heterogeneous in terms of participant age, probiotic strain, species, dosage, intervention duration, and form of administration. Additional clinical trials are warranted to determine the most effective strains of probiotics, doses and durations of interventions.

Carbohydrates effects on nutrition and health functions in pigs

The greatest improvement in carbohydrates studies on pig nutrition and health is that carbohydrates are classified more clearly, which is based not only on their chemical structure but also on their physiological characteristics. Besides its primary energy source, different types and structures of carbohydrates are a benefit for nutrition and health functions in pigs, which are involved in promoting growth performance and intestinal functions, regulating the community of gut microbiota, and modulating the lipids and glucose metabolism. The underlying mechanism of carbohydrates regulates the lipids and glucose metabolism through their metabolites (short-chain fatty acids [SCFAs]) and mainly via the SCFAs-GPR43/41-PYY/GLP1, SCFAs-AMP/ATP-AMPK, and SCFAs-AMPK-G6Pase/PEPCK pathways. Emerging research had evaluated an optimal combination in different types and structures of carbohydrates, which could enhance growth performance and nutrient digestibility, promote intestinal functions, and increase the abundances of butyrate-producing bacteria in pigs. Overall, compelling evidence supports the notion that carbohydrates play important roles in both nutrition and health functions in pigs. Moreover, identifying the carbohydrates combinations will be of both theoretical and practical values for developing the technology of carbohydrates balance in pigs.

Identification of the relationship between the gut microbiome and feed efficiency in a commercial pig cohort

Feed efficiency (FE) is an economically important trait in pig production. Gut microbiota plays an important role in energy harvest, nutrient metabolism, and fermentation of dietary indigestible components. Whether and which gut microbes affect FE in pigs are largely unknown. Here, a total of 208 healthy Duroc pigs were used as experimental materials. Feces and serum samples were collected at the age of 140 d. We first performed 16S rRNA gene and metagenomic sequencing analysis to investigate the relationship between the gut microbiome and porcine residual feed intake (RFI). 16S rRNA gene sequencing analysis detected 21 operational taxonomic units showing the tendency to correlation with the RFI (P < 0.01). Metagenomic sequencing further identified that the members of Clostridiales, e.g., Ruminococcus flavefaoiens, Lachnospiraceae bacterium 28-4, and Lachnospiraceae phytofermentans, were enriched in pigs with low RFI (high-FE), while 11 bacterial species including 5 Prevotella spp., especially, the Prevotella copri, had higher abundance in pigs with high RFI. Functional capacity analysis suggested that the gut microbiome of low RFI pigs had a high abundance of the pathways related to amino acid metabolism and biosynthesis, but a low abundance of the pathways associated with monosaccharide metabolism and lipopolysaccharide biosynthesis. Serum metabolome and fecal short-chain fatty acids were determined by UPLC-QTOF/MS and gas chromatography, respectively. Propionic acid in feces and the serum metabolites related to amino acid metabolism were negatively correlated with the RFI. The results from this study may provide potential gut microbial biomarkers that could be used for improving FE in pig production industry.

Intestinal Health and Threonine Requirement of Growing Pigs Fed Diets Containing High Dietary Fibre and Fermentable Protein

Simple Summary

Dietary components, such as fibre and protein, have significant impacts on nutrient requirements and intestinal health in pigs. The objectives of this study were to investigate the interactive effects of dietary fibre and fermentable protein on threonine requirement for protein deposition in growing pigs and to determine how these factors affect markers of intestinal health. In this study we used the nitrogen-balance approach to study the influence of high protein diets combined with high fibre on threonine requirement for protein deposition. We further used gene expression, fermentation metabolites (short and branched chain fatty acid concentration), and serum antioxidant status in these pigs as markers of intestinal health and function. We demonstrate that high fibre will indeed increase threonine requirement for protein deposition but can mitigate the negative effects of fermentable protein metabolites on intestinal health. These results will have implications for the development of dietary strategies to improve growth and overall health in pigs, including adjustments to dietary fibre, protein, and amino acid content that maximize pig growth, nutrient utilization, and intestinal health.

Abstract

Dietary fibre (DF) and fermentable crude protein (fCP) are dietary factors which affect nutrient utilization and intestinal health in pigs. A nitrogen (N)-balance study was conducted to determine the impact of DF and fCP on threonine (Thr) requirement for protein deposition (PD) and indicators of intestinal health. A total of 160 growing pigs (25 kg) were randomly assigned to 1 of 20 dietary treatments in a 2 × 2 × 5 factorial arrangement in a randomized complete block design with dietary fibre (low (LF) or high fibre (HF)], fCP [low (LfCP) or high fCP (HfCP)) and Thr (0.52, 0.60, 0.68, 0.76, or 0.82% standardized ileal digestible) as factors. Then, 4-day total urine and fecal collection was conducted, and pigs were euthanized for intestinal tissue and digesta sampling. Feeding high DF, regardless of fCP content, increased Thr requirement for PD (p < 0.05). High fCP, regardless of DF content, reduced Thr requirement for PD. Serum antioxidant capacity increased as dietary Thr level increased (p < 0.05). Cecal digesta short-chain fatty acids (SCFA) increased (p < 0.05) with HF and branched-chain fatty acids (BCFA) increased with HfCP and reduced with HF (p < 0.05). HfCP reduced (p < 0.05) mucin-2 (MUC2) expression in the colon of the HF but not the LF fed pigs and HF increased MUC2 in the LfCP but not the HfCP fed pigs. Feeding HF diet increased (p < 0.05) expression of zonula occludens-1 in the LfCP with no effect on HfCP fed pigs. Ammonia concentration in both cecum and colon increased (p < 0.05) in the HfCP fed pigs. Overall, high DF reduced the negative impact of HfCP on intestinal health, as indicated by alterations in SCFA and BCFA production and gut barrier gene expression. While increased dietary Thr content is required for PD in pigs fed high DF, feeding high fCP reduced Thr requirements.

Long-Term Intake of Pork Meat Proteins Altered the Composition of Gut Microbiota and Host-Derived Proteins in the Gut Contents of Mice

SCOPE

This study is to investigate the effects of long-term intake of pork protein on the composition of gut microbiota and proteins in mice.

METHODS AND RESULTS

C57BL/6J mice are fed pork meat protein diets for 240 days, and the composition of gut microbiota and proteins in luminal contents from the duodenum to the colon are analyzed by 16S rRNA gene sequencing and LC-MS/MS. The stewed pork protein diet group has a highly similar microbiota composition to that of the cooked pork protein diet group, but different from the pork emulsion sausage or dry-cured pork protein diet groups. Lachnospiraceae NK4A136, Odoribacter, Defluviitaleaceae UCG-011, Ruminiclostridium 9, Blautia, Lachnoclostridium, and Ruminococcaceae UCG-010 play an important role in response to changes in gut luminal proteins. Specific microbes are significantly correlated with the Cela3b and Cpa1 that are derived from the host and involve protein digestion and absorption.

CONCLUSIONS

Pork meat protein diets alter the gut microbiota composition and specific gut microbes may have a great impact on protein digestion and absorption by regulating the secretion of digestive proteins from the host. These findings provide a new insight into the associations of long-term intake of meat protein diet with gut microbiota and host.

Dietary protein levels and amino acid supplementation patterns alter the composition and functions of colonic microbiota in pigs

Different dietary nitrogen (N) patterns may have different effects on gut microbiota. To investigate the effects of different crude protein (CP) levels or essential amino acids (EAA) supplementation patterns on the structure and functions of colonic microbiota, 42 barrows (25 ± 0.39 kg) were randomly assigned to 7 dietary treatments including: diet 1, a high CP diet with balanced 10 EAA; diet 2, a medium CP diet with approximately 2% decreased CP level from diet 1 and balanced 10 EAA; diets 3, 4, 5, 6 and 7, low CP diets with 4% decreased CP level from diet 1. Specifically, diet 3 was only balanced for Lys, Met, Thr and Trp; diets 4, 5 and 6 were further supplemented with Ile, Val and Ile + Val on the basis of diet 3, respectively; and diet 7 was balanced for 10 EAA. Results over a 110-d trial showed that reducing the CP level by 2% or 4% dramatically decreased N intake and excretion (P < 0.05) in the presence of balanced 10 EAA, which was not observed when altering the EAA supplementation patterns in low CP diet (−4%). With balanced 10 EAA, 2% reduction in dietary CP significantly reduced Firmicutes-to-Bacteroidetes (F:B) ratio and significantly elevated the abundance of Prevotellaceae NK3B31 (P < 0.05); whereas 4% reduction evidently increased the abundances of Proteobacteria, Succinivibrio and Lachnospiraceae XPB1014 (P < 0.05). Among the 5 low CP diets (−4%), supplementation with Ile, or Val + Ile, or balanced 10 EAA increased F:B ratio and the abundance of Proteobacteria. In addition, the predicted functions revealed that different CP levels and EAA balanced patterns dramatically altered the mRNA expression profiles of N-metabolizing genes, the “N and energy metabolism” pathways or the metabolism of some small substances, such as amino acids (AA) and vitamins. Our findings suggested that reducing the dietary CP levels by 2% to 4% with balancing 10 EAA, or only further supplementation with Ile or Val + Ile to a low protein diet (−4%) reduced the N contents entering the hindgut to various degrees, altered the abundances of N-metabolizing bacteria, and improved the abilities of N utilization.

Potential relevance of pig gut content transplantation for production and research

It is becoming increasingly evident that the gastrointestinal microbiota has a significant impact on the overall health and production of the pig. This has led to intensified research on the composition of the gastrointestinal microbiota, factors affecting it, and the impact of the microbiota on health, growth performance, and more recently, behavior of the host. Swine production research has been heavily focused on assessing the effects of feed additives and dietary modifications to alter or take advantage of select characteristics of gastrointestinal microbes to improve health and feed conversion efficiency. Research on faecal microbiota transplantation (FMT) as a possible tool to improve outcomes in pigs through manipulation of the gastrointestinal microbiome is very recent and limited data is available. Results on FMT in humans demonstrating the transfer of phenotypic traits from donors to recipients and the high efficacy of FMT to treat Clostridium difficile infections in humans, together with data from pigs relating GI-tract microbiota composition with growth performance has likely played an important role in the interest towards this strategy in pig production. However, several factors can influence the impact of FMT on the recipient, and these need to be identified and optimized before this tool can be applied to pig production. There are obvious inherent biosecurity and regulatory issues in this strategy, since the donor's microbiome can never be completely screened for all possible non-desirable microorganisms. However, considering the success observed in humans, it seems worth investigating this strategy for certain applications in pig production. Further, FMT research may lead to the identification of specific bacterial group(s) essential for a particular outcome, resulting in the development of banks of clones which can be used as targeted therapeutics, rather than the broader approach applied in FMT. This review examines the factors associated with the use of FMT, and its potential application to swine production, and includes research on using the pig as model for human medical purposes.

In vitro evaluation of the effects of Yucca schidigera and inulin on the fermentation potential of the faecal microbiota of dogs fed diets with low or high protein concentrations

This in vitro study aimed to evaluate the effects of Yucca schidigera powder (YSP) and inulin (IN) on protein fermentation metabolites (short-chain fatty acids [SCFA] and branched-chain fatty acids, phenolic and indolic compounds, biogenic amines, ammonia and pH) by using faecal inocula from dogs fed either a low (L) or a high (H) protein diet (crude protein 201 or 377 g/kg as fed). Four treatments for each diet were evaluated in an in vitro batch culture system over 24 h: (1) control with no addition of substrates; (2) 4 g YSP/l; (3) 5 g IN/l; (4) 4 g YSP/l in combination with 5 g IN/l of faecal culture of dogs fed Diet L or H. Several changes in fermentation metabolites were analysed. Samples incubated with the faecal inocula of dogs fed Diet L produced higher concentrations of total SCFA, propionate (p = 0.001), acetate (p ≤ 0.001), d-lactate (p = 0.041) and indole (p = 0.003), whereas pH (p = 0.004) was decreased. Supplementation of IN increased the content of putrescine, d- and l-lactate, total SCFA, acetate, propionate, n-butyrate (p ≤ 0.001) and n-valerate (p = 0.003), while i-valerate, indole and pH (p ≤ 0.001) were reduced. Ammonia was lower (p = 0.013) in samples with faecal inocula from dogs fed Diet H and further reduced by the addition of IN (p ≤ 0.001). Samples with faecal inocula from dogs fed Diet L had a fewer quotient of ammonia and total SCFA (p = 0.040). Supplementation of YSP (p = 0.021), IN (p ≤ 0.001) and YSP in combination with IN (p = 0.047) led to a higher reduction of the quotient of ammonia and total SCFA. In conclusion, dietary protein concentration and the supplementation of IN resulted in a stimulation of fermentation while YSP appeared to have only minor effects.

Effects of fermented soybean meal on carbon and nitrogen metabolisms in large intestine of piglets

Fermented soybean meal (FSM), which has lower anti-nutritional factors and higher active enzyme, probiotic and oligosaccharide contents than its unfermented form, has been reported to improve the feeding value of soybean meal, and hence, the growth performance of piglets. However, whether FSM can affect the bacterial and metabolites in the large intestine of piglets remains unknown. This study supplemented wet-FSM (WFSM) or dry-FSM (DFSM) (5% dry matter basis) in the diet of piglets and investigated its effects on carbon and nitrogen metabolism in the piglets' large intestines. A total of 75 41-day-old Duroc×Landrace×Yorkshire piglets with an initial BW of 13.14±0.22 kg were used in a 4-week feeding trial. Our results showed that the average daily gain of piglets in the WFSM and DFSM groups increased by 27.08% and 14.58% and that the feed conversion ratio improved by 18.18% and 7.27%, respectively, compared with the control group. Data from the prediction gene function of Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) based on 16S ribosomal RNA (rRNA) sequencing showed that carbohydrate metabolism function families in the WFSM and DFSM groups increased by 3.46% and 2.68% and that the amino acid metabolism function families decreased by 1.74% and 0.82%, respectively, compared with the control group. These results were consistent with those of other metabolism studies, which showed that dietary supplementation with WFSM and DFSM increased the level of carbohydrate-related metabolites (e.g. 4-aminobutanoate, 5-aminopentanoate, lactic acid, mannitol, threitol and β-alanine) and decreased the levels of those related to protein catabolism (e.g. 1,3-diaminopropane, creatine, glycine and inosine). In conclusion, supplementation with the two forms of FSM improved growth performance, increased metabolites of carbohydrate and reduced metabolites of protein in the large intestine of piglets, and WFSM exhibited a stronger effect than DFSM.

Dietary changes in nutritional studies shape the structural and functional composition of the pigs' fecal microbiome-from days to weeks

BACKGROUND

The possible impact of changes in diet composition on the intestinal microbiome is mostly studied after some days of adaptation to the diet of interest. The question arises if a few days are enough to reflect the microbial response to the diet by changing the community composition and function. The present study investigated the fecal microbiome of pigs during a time span of 4 weeks after a dietary change to obtain insights regarding the time required for adaptation. Four different diets were used differing in either protein source (field peas meal vs. soybean meal) or the concentration of calcium and phosphorus (CaP).

RESULTS

Twelve pigs were sampled at seven time points within 4 weeks after the dietary change. Fecal samples were used to sequence the 16S rRNA gene amplicons to analyse microbial proteins via LC-MS/MS and to determine the SCFA production. The analysis of OTU abundances and quantification values of proteins showed a significant separation of three periods of time (p = 0.001). Samples from the first day are used to define the 'zero period'; samples of weeks 1 and 2 are combined as 'metabolic period' and an 'equilibrium period was defined based on samples from weeks 3 and 4. Only in this last period, a separation according to the supplementation of CaP was significantly detectable (p = 0.001). No changes were found based on the corn-soybean meal or corn-field peas administration. The analysis of possible factors causing this significant separation showed only an overall change of bacterial members and functional properties. The metaproteomic approach yielded a total of about 9700 proteins, which were used to deduce possible metabolic functions of the bacterial community.

CONCLUSIONS

A gradual taxonomic and functional rearrangement of the bacterial community has been depicted after a change of diet composition. The adaptation lasts several weeks despite the usually assumed time span of several days. The obtained knowledge is of a great importance for the design of future nutritional studies. Moreover, considering the high similarities between the porcine and human gastrointestinal tract anatomy and physiology, the findings of the current study might imply in the design of human-related nutritional studies.

Exploring a Possible Link between the Intestinal Microbiota and Feed Efficiency in Pigs

Feed efficiency (FE) is critical in pig production for both economic and environmental reasons. As the intestinal microbiota plays an important role in energy harvest, it is likely to influence FE. Therefore, our aim was to characterize the intestinal microbiota of pigs ranked as low, medium, and high residual feed intake ([RFI] a metric for FE), where genetic, nutritional, and management effects were minimized, to explore a possible link between the intestinal microbiota and FE. Eighty-one pigs were ranked according to RFI between weaning and day 126 postweaning, and 32 were selected as the extremes in RFI (12 low, 10 medium, and 10 high). Intestinal microbiota diversity, composition, and predicted functionality were assessed by 16S rRNA gene sequencing. Although no differences in microbial diversity were found, some RFI-associated compositional differences were revealed, principally among members of Firmicutes, predominantly in feces at slaughter (albeit mainly for low-abundance taxa). In particular, microbes associated with a leaner and healthier host (e.g., Christensenellaceae, Oscillibacter, and Cellulosilyticum) were enriched in low RFI (more feed-efficient) pigs. Differences were also observed in the ileum of low RFI pigs; most notably, Nocardiaceae (Rhodococcus) were less abundant. Predictive functional analysis suggested improved metabolic capabilities in these animals, especially within the ileal microbiota. Higher ileal isobutyric acid concentrations were also found in low RFI pigs. Overall, the differences observed within the intestinal microbiota of low RFI pigs compared with that of their high RFI counterparts, albeit relatively subtle, suggest a possible link between the intestinal microbiota and FE in pigs.IMPORTANCE This study is one of the first to show that differences in intestinal microbiota composition, albeit subtle, may partly explain improved feed efficiency (FE) in low residual feed intake (RFI) pigs. One of the main findings is that, although microbial diversity did not differ among animals of varying FE, specific intestinal microbes could potentially be linked with porcine FE. However, as the factors impacting FE are still not fully understood, intestinal microbiota composition may not be a major factor determining differences in FE. Nonetheless, this work has provided a potential set of microbial biomarkers for FE in pigs. Although culturability could be a limiting factor and intervention studies are required, these taxa could potentially be targeted in the future to manipulate the intestinal microbiome so as to improve FE in pigs. If successful, this has the potential to reduce both production costs and the environmental impact of pig production.

Health relevance of intestinal protein fermentation in young pigs

The physiological role of the gastrointestinal microbiota has become an important subject of nutrition research in pigs in the past years, and the importance of intestinal microbial activity in the etiology of disease is doubtless. This review summarizes the recent knowledge related to the microbial ecology of protein fermentation and the appearance of protein-derived metabolites along the pig intestine. The amount of fermentable protein depends on factors such as dietary protein concentration, protein digestibility due to secondary or tertiary structure, the interaction with dietary compounds or anti-nutritional factors, and the secretion of endogenous proteins into the gut lumen. High protein diets increase the luminal concentrations and epithelial exposure to putatively toxic metabolites and increase the risk for post-weaning diarrhea, but the mechanisms are not yet clarified. Although the use of fermentable carbohydrates to reduce harmful protein-derived metabolites in pigs is well-established, recent studies suggest that the inclusion of fermentable carbohydrates into diets with low protein digestibility or high dietary protein level may not ameliorate all negative effects with regard to epithelial response. Based on the current knowledge, the use of diets with low levels of high-quality protein may help to reduce the risk for intestinal disease in young pigs.

Inhibitory effects of laminaran and alginate on production of putrefactive compounds from soy protein by intestinal microbiota in vitro and in rats

Soybean is one of the major components of the Japanese diet. In traditional Japanese cuisine, soybean-based food items are often consumed with brown algae. In this study, we examined the effect of water-soluble and fermentable polysaccharides, laminaran and sodium alginate, from brown algae, on putrefactive compound production, by human faecal microbiota in broth containing 3% (w/v) soy protein. We also investigated the effect of 2% laminaran or alginate diet on caecal putrefactive compounds in rats maintained on diets containing 20% (w/w) soy protein. The caecal microbiota was also analysed using denaturing gradient gel electrophoresis and pyrosequencing with primers targeting the bacterial 16S rRNA gene. The polysaccharides, particularly laminaran, inhibited ammonia, phenol, and indole production by human faecal microbiota. Both the algal polysaccharides lowered the caecal indole content. Laminaran was found to increase the number of Coprobacter, whereas Helicobacter was found to decrease in the presence of both laminaran and sodium alginate.

High Amylose Starch with Low In Vitro Digestibility Stimulates Hindgut Fermentation and Has a Bifidogenic Effect in Weaned Pigs

BACKGROUND

Dietary amylose resists enzymatic digestion, thereby providing a substrate for microbial fermentation that stimulates proliferation of beneficial microbiota and production of short-chain fatty acids (SCFAs) in the large intestine of pigs and humans. However, the effect of increasing dietary amylose in pigs immediately postweaning on growth, nutrient digestibility and flow, and intestinal microbial and SCFA profiles has not been studied and can be used as a model for newly weaned human infants.

OBJECTIVE

We studied the effects of increasing dietary amylose on growth, nutrient digestibility, and intestinal microbial and metabolite profiles in weaned pigs.

METHODS

Weaned pigs (n = 32) were randomly allocated to 1 of 4 diets containing 67% starch with 0%, 20%, 28%, or 63% amylose for 21 d. Subsequently, pigs were killed to collect feces and digesta for measuring starch digestion and microbial and metabolite profiles.

RESULTS

Feeding weaned pigs 63% compared with 0%, 20%, and 28% amylose decreased (P < 0.05) feed intake by 5% and growth by ≥ 12%. Ileal digestibility of dry matter decreased (P < 0.05) by 10% and starch by 9%, thereby increasing (P < 0.05) hindgut fermentation, cecal and colonic total SCFAs, and colonic Bacteroides, and lowering (P < 0.01) ileal, cecal, and colonic pH in pigs consuming 63% compared with 0%, 20%, and 28% amylose. Cecal and colonic Bifidobacteria spp. increased by 14-30% (P < 0.05) and Clostridium clusters IV and XIVa were decreased (P < 0.01) in pigs consuming 63% compared with 0%, 20%, and 28% amylose.

CONCLUSION

Increasing dietary amylose in pigs immediately postweaning stimulated hindgut fermentation and Bifidobacteria spp., thereby manipulating the gut environment, but also reduced intake and growth. An optimum dietary amylose concentration should be determined, which would maintain desired growth rate and gut environment in weaned pigs.

Barcoded pyrosequencing-based metagenomic analysis of the faecal microbiome of three purebred pig lines after cohabitation

The microbial communities in the pig gut perform a variety of beneficial functions. Along with host genetics and diet, farm management practices are an important aspect of agricultural animal production that could influence gut microbial diversity. In this study, we used barcoded pyrosequencing of the V1-V3 regions of the 16S ribosomal RNA (rRNA) genes to characterise the faecal microbiome of three common commercial purebred pig lines (Duroc, Landrace and Yorkshire) before and after cohabitation. The diversity of faecal microbiota was characterised by employing phylogenetic, distance-based and multivariate-clustering approaches. Bacterial diversity tended to become more uniform after mixing of the litters. Age-related shifts were also observed at various taxonomic levels, with an increase in the proportion of the phylum Firmicutes and a decrease in Bacteroidetes over time, regardless of the purebred group. Cohabitation had a detectable effect on the microbial shift among purebred pigs. We identified the bacterial genus Parasutterella as having utility in discriminating pigs according to time. Similarly, Dialister and Bacteroides can be used to differentiate the purebred lines used. The microbial communities of the three purebred pigs became more similar after cohabitation, but retained a certain degree of breed specificity, with the microbiota of Landrace and Yorkshire remaining distinct from that of their distant relative, Duroc.

Dietary fibre and crude protein: impact on gastrointestinal microbial fermentation characteristics and host response

The role of the gastrointestinal tract microbiota in animal health and nutrition has become the subject of intensive research. Carbohydrates and crude protein are major components of swine diets and numerous studies have been performed looking at the effect of inclusion of dietary fibre with possible functional properties. In recent years, our understanding of the diversity and functionality of the gastrointestinal tract microbiota has increased further enabling the possibility for their targeted modulation. However, favouring potential beneficial bacteria, inhibiting possible pathogens or promotion of the formation of desired metabolites, is complex and underlies many factors and uncertainties. Approaches targeting this complex ecosystem (and discussed in this review) include the utilisation of fermentable carbohydrates such as resistant starch, cereal 1–3/1–4 β-glucans, arabinoxylans, inulin or other sources from legumes and industrial by-products. In addition, strategies regarding protein level and the protein : carbohydrate ratio are discussed briefly. Results are both promising and sometimes rather disillusioning considering the dietary concentrations needed to show biologically relevant effects. Deriving recommendations for an optimal inclusion rate of dietary fibre for weaning, growing pigs and sows and maximum levels for dietary crude protein may be one of the main challenges in the near future in the swine industry.

Interaction between dietary protein content and the source of carbohydrates along the gastrointestinal tract of weaned piglets

Although fermentable carbohydrates (CHO) can reduce metabolites derived from dietary protein fermentation in the intestine of pigs, the interaction between site of fermentation and substrate availability along the gut is still unclear. The current study aimed at determining the impact of two different sources of carbohydrates in diets with low or very high protein content on microbial metabolite profiles along the gastrointestinal tract of piglets. Thirty-six piglets (n = 6 per group) were fed diets high (26%, HP) or low (18%, LP) in dietary protein and with or without two different sources of carbohydrates (12% sugar beet pulp, SBP, or 8% lignocellulose, LNC) in a 2 × 3 factorial design. After 3 weeks, contents from stomach, jejunum, ileum, caecum, proximal and distal colon were taken and analysed for major bacterial metabolites (D-lactate, L-lactate, short chain fatty acids, ammonia, amines, phenols and indols). Results indicate considerable fermentation of CHO and protein already in the stomach. HP diets increased the formation of ammonia, amines, phenolic and indolic compounds throughout the different parts of the intestine with most pronounced effects in the distal colon. Dietary SBP inclusion in LP diets favoured the formation of cadaverine in the proximal parts of the intestine. SBP mainly increased CHO-derived metabolites such as SCFA and lactate and decreased protein-derived metabolites in the large intestine. Based on metabolite profiles, LNC was partly fermented in the distal large intestine and reduced mainly phenols, indols and cadaverine, but not ammonia. Multivariate analysis confirmed more diet-specific metabolite patterns in the stomach, whereas the CHO addition was the main determinant in the caecum and proximal colon. The protein level mainly influenced the metabolite patterns in the distal colon. The results confirm the importance of CHO source to influence the formation of metabolites derived from protein fermentation along the intestinal tract of the pig.

Caecal fermentation, putrefaction and microbiotas in rats fed milk casein, soy protein or fish meal

To clarify the effect of soy protein (SP) and fish meal (FM), compared to milk casein (MC), on the intestinal environment, we examined caecal environment of rats fed the test diets. Four-week-old rats were fed AIN-76-based diet containing 20 %, w/w MC, SP or FM for 16 days. Caecal organic acids were analysed by HPLC. Caecal putrefactive compounds (indole, phenol, H2S and ammonia) were analysed by colorimetric assays. Caecal microflora was determined by 16S rRNA gene-DGGE and pyrosequencing with bar-coded primers targeting the bacterial 16S rRNA gene. n-Butyric and lactic acid levels were high in rats fed SP and FM, respectively. Butyrate-producing bacteria, such as Oscillibacter, and lactate-producing bacteria, such as Lactobacillus, were detected in each diet group. Also, the putrefactive compound contents were high in rats fed SP and FM. In this study, both DGGE and pyrosequencing analyses were able to evaluate the dynamics of the intestinal microbiota. The results indicate that dietary proteins can alter the intestinal environment, affecting fermentation by the intestinal microbiota and the generation of putrefactive compounds.

Changing dietary calcium-phosphorus level and cereal source selectively alters abundance of bacteria and metabolites in the upper gastrointestinal tracts of weaned pigs

Several dietary ingredients may affect the bacterial community structure and metabolism in the porcine gut and may therefore influence animals' health and performance. This study investigated the effects of cereal source and calcium-phosphorus (CaP) level in the diet on bacterial microbiota and metabolites, nutrient intake, and gut environment in weaned pigs. Pigs (n=8/treatment) were fed wheat-barley- or corn-based diets with an adequate or high CaP level for 14 days. Effects on microbiota in the stomach, ileum, and midcolon were assessed using quantitative PCR. Data showed that Enterobacteriaceae, Campylobacter spp., and Helicobacter spp., which all contain highly immune reactive lipopolysaccharide (LPS), were abundant at all gut sites. Diet effects on bacteria and metabolites were moderate and occurred mainly in the upper gut, whereas no effects on bacteria, fermentation products, and LPS could be observed in the colon. Differences in carbohydrate intake with corn versus wheat-barley diets selectively stimulated Bifidobacterium in the stomach and ileum. There was a growth advantage for a few bacterial groups in the stomach and ileum of pigs fed the high versus adequate CaP level (i.e., gastric Enterobacteriaceae and ileal Enterococcus, Bacteroides-Prevotella-Porphyromonas, and Campylobacter). Interestingly, gastrointestinal pH was not affected by dietary CaP level. The present findings demonstrate the stability of the bacterial community and gut environment toward dietary changes even in young pigs. The results on stimulation of gastric and ileal Bifidobacterium by corn diets may be employed in nutritional strategies to support gut health after weaning.

FLX pyrosequencing analysis of the effects of the brown-algal fermentable polysaccharides alginate and laminaran on rat cecal microbiotas

Edible brown algae are used as major food material in Far East Asian countries, particularly in South Korea and Japan. They contain fermentable dietary fibers, alginic acid (uronic acid polymer) and laminaran (β-1,3-glucan), that are fermented into organic acids by intestinal bacteria. To clarify the effect of edible algae on the intestinal environment, the cecal microbiotas of rats fed diets containing no dietary fiber (control) or 2% (wt/wt) sodium alginate or laminaran for 2 weeks were analyzed using FLX amplicon pyrosequencing with bar-coded primers targeting the bacterial 16S rRNA gene. The most abundant phylum in all groups was Firmicutes. Specifically, Allobaculum was dominant in all diet groups. In addition, Bacteroides capillosus (37.1%) was abundant in the alginate group, while Clostridium ramosum (3.14%) and Parabacteroides distasonis (1.36%) were only detected in the laminaran group. Furthermore, rats fed alginate showed simplified microbiota phylotypes compared with others. With respect to cecal chemical compounds, laminaran increased cecal organic acid levels, particularly propionic acid. Alginate increased total cecal organic acids. Cecal putrefactive compounds, such as indole, H(2)S, and phenol, were decreased by both alginate and laminaran. These results indicate that edible brown algae can alter the intestinal environment, with fermentation by intestinal microbiota.

Modulation of systemic immune responses through commensal gastrointestinal microbiota

Colonization of the gastrointestinal (GI) tract is initiated during birth and continually seeded from the individual's environment. Gastrointestinal microorganisms play a central role in developing and modulating host immune responses and have been the subject of investigation over the last decades. Animal studies have demonstrated the impact of GI tract microbiota on local gastrointestinal immune responses; however, the full spectrum of action of early gastrointestinal tract stimulation and subsequent modulation of systemic immune responses is poorly understood. This study explored the utility of an oral microbial inoculum as a therapeutic tool to affect porcine systemic immune responses. For this study a litter of 12 pigs was split into two groups. One group of pigs was inoculated with a non-pathogenic oral inoculum (modulated), while another group (control) was not. DNA extracted from nasal swabs and fecal samples collected throughout the study was sequenced to determine the effects of the oral inoculation on GI and respiratory microbial communities. The effects of GI microbial modulation on systemic immune responses were evaluated by experimentally infecting with the pathogen Mycoplasma hyopneumoniae. Coughing levels, pathology, toll-like receptors 2 and 6, and cytokine production were measured throughout the study. Sequencing results show a successful modulation of the GI and respiratory microbiomes through oral inoculation. Delayed type hypersensitivity responses were stronger (p = 0.07), and the average coughing levels and respiratory TNF-α variance were significantly lower in the modulated group (p<0.0001 and p = 0.0153, respectively). The M. hyopneumoniae infection study showed beneficial effects of the oral inoculum on systemic immune responses including antibody production, severity of infection and cytokine levels. These results suggest that an oral microbial inoculation can be used to modulate microbial communities, as well as have a beneficial effect on systemic immune responses as demonstrated with M. hyopneumoniae infection.

Fermentable fiber ameliorates fermentable protein-induced changes in microbial ecology, but not the mucosal response, in the colon of piglets

Dietary inclusion of fermentable carbohydrates (fCHO) is reported to reduce large intestinal formation of putatively toxic metabolites derived from fermentable proteins (fCP). However, the influence of diets high in fCP concentration on epithelial response and interaction with fCHO is still unclear. Thirty-two weaned piglets were fed 4 diets in a 2 × 2 factorial design with low fCP/low fCHO [14.5% crude protein (CP)/14.5% total dietary fiber (TDF)]; low fCP/high fCHO (14.8% CP/16.6% TDF); high fCP low fCHO (19.8% CP/14.5% TDF); and high fCP/high fCHO (20.1% CP/18.0% TDF) as dietary treatments. After 21-23 d, pigs were killed and colon digesta and tissue samples analyzed for indices of microbial ecology, tissue expression of genes for cell turnover, cytokines, mucus genes (MUC), and oxidative stress indices. Pig performance was unaffected by diet. fCP increased (P < 0.05) cell counts of clostridia in the Clostridium leptum group and total short and branched chain fatty acids, ammonia, putrescine, histamine, and spermidine concentrations, whereas high fCHO increased (P < 0.05) cell counts of clostridia in the C. leptum and C. coccoides groups, shifted the acetate to propionate ratio toward acetate (P < 0.05), and reduced ammonia and putrescine (P < 0.05). High dietary fCP increased (P < 0.05) expression of PCNA, IL1β, IL10, TGFβ, MUC1, MUC2, and MUC20, irrespective of fCHO concentration. The ratio of glutathione:glutathione disulfide was reduced (P < 0.05) by fCP and the expression of glutathione transferase was reduced by fCHO (P < 0.05). In conclusion, fermentable fiber ameliorates fermentable protein-induced changes in most measures of luminal microbial ecology but not the mucosal response in the large intestine of pigs.

Dose-dependent effects of dietary zinc oxide on bacterial communities and metabolic profiles in the ileum of weaned pigs

Pharmacological levels of zinc oxide (ZnO) can improve the health of weaning piglets and influence the intestinal microbiota. This experiment aimed at studying the dose-response effect of five dietary concentrations of ZnO on small intestinal bacteria and metabolite profiles. Fifteen piglets, weaned at 25 ± 1 days of age, were allocated into five groups according to body weight and litter. Diets were formulated to contain 50 (basal diet), 150, 250, 1000 and 2500 mg zinc/kg by adding analytical-grade (>98% purity) ZnO to the basal diet and fed ad libitum for 14 days after a 7-day adaptation period on the basal diet. Ileal bacterial community profiles were analysed by denaturing gradient gel electrophoresis and selected bacterial groups quantified by real-time PCR. Concentrations of ileal volatile fatty acids (VFA), D- and L-lactate and ammonia were determined. Species richness, Shannon diversity and evenness were significantly higher at high ZnO levels. Quantitative PCR revealed lowest total bacterial counts in the 50 mg/kg group. Increasing ZnO levels led to an increase (p = 0.017) in enterobacteria from log 4.0 cfu/g digesta (50 mg/kg) to log 6.7 cfu/g digesta (2500 mg/kg). Lactic acid bacteria were not influenced (p = 0.687) and clostridial cluster XIVa declined (p = 0.035) at highest ZnO level. Concentration of total, D- and L-lactate and propionate was not affected (p = 0.736, p = 0.290 and p = 0.630), but concentrations of ileal total VFA, acetate and butyrate increased markedly from 50 to 150 mg/kg and decreased with further increasing zinc levels and reached low levels again at 2500 mg/kg (p = 0.048, p = 0.048 and p = 0.097). Ammonia decreased (p < 0.006) with increasing dietary ZnO level. In conclusion, increasing levels of dietary ZnO had strong and dose-dependent effects on ileal bacterial community composition and activity, suggesting taxonomic variation in metabolic response to ZnO.