SCFAs-Induced GLP-1 Secretion Links the Regulation of Gut Microbiome on Hepatic Lipogenesis in Chickens

Glucagon-like peptide-1 analog liraglutide reduces fat deposition in chicken adipocytes

Previously, we reported that glucagon-like peptide-1 (GLP-1) and its analog liraglutide could inhibit fat de novo synthesis in the liver and reduce abdominal fat accumulation in broiler chickens. Nevertheless, the impact of GLP-1 on adipocyte fat deposition remains enigmatic. This study aimed to investigate the effects of GLP-1, via its analog liraglutide, on chicken chicken adipocytes in vitro. Chemical assays, quantitative real-time polymerase chain reaction (qRT-PCR), and western blot were employed to assess the proliferation, differentiation, and fat deposition of chicken adipocytes. Our findings indicated that liraglutide significantly suppressed cell proliferation and promoted preadipocyte differentiation in comparison to the control group. This was evidenced by elevated triglyceride (TG) content and upregulated mRNA expression of lipogenesis-related enzymes, such as acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS), as well as regulators including peroxisome proliferator-activated receptor γ (PPARγ), sterol regulatory element binding protein-1 (SREBP1) and CCAAT/enhancer binding protein α (CEBPα). In mature adipocytes, liraglutide attenuated fat deposition by inhibiting fat de novo synthesis, evidenced by decreased mRNA expression of ACC, FAS, PPARγ, C/EBPα, and SREBP1, and concurrent upregulation of phosphorylated AMP-activated protein kinase (p-AMPK) and phosphorylated ACC (p-ACC). This resulted in reduced accumulation of lipid droplets and TG content in mature adipocytes. Collectively, our findings indicate that liraglutide suppresses the proliferation of preadipocytes, enhances their differentiation, and concurrently inhibits de novo lipogenesis in mature adipocytes. This observation offers profound insights into the mechanisms that underlie liraglutide's anti-adipogenic effects, which could have significant implications for the treatment of obesity in broiler chickens.

Huanglian-banxia promotes gastric motility of diabetic rats by modulating brain-gut neurotransmitters through MAPK signaling pathway

BACKGROUND

Gastric motility disorder is an increasingly common problem among people with diabetes. Neurotransmitters have been recognized as critical regulators in the process of gastric motility. Previous study has shown that herb pair huanglian-banxia (HL-BX) can improve gastric motility, but the underlying mechanism is still unclear. The aim of this study was to further investigate the role of HL-BX in modulating brain-gut neurotransmission to promote gastric motility in diabetic rats, and to explore its possible mechanism.

METHODS

The diabetic rats were divided into five groups. Gastric emptying rate, intestinal propulsion rate, body weight, and average food intake were determined. Substance P (SP), 5- hydroxytryptamine (5-HT), and glucagon-like peptide -1 (GLP-1) in the serum were measured by enzyme-linked immunosorbent assay. Dopamine (DA) and norepinephrine (NE) in the brain were analyzed by high-pressure liquid chromatography with a fluorescence detector. Protein expression of the tissues in the stomach and brain was determined by Western blot.

KEY RESULTS

HL-BX reduced average food intake significantly, increased body weight, and improved gastric emptying rate and intestinal propulsion rate. HL-BX administration caused a significant increase in SP, GLP-1, and 5-HT, but a significant decrease in DA and NE. Interestingly, HL-BX regulated simultaneously the different expressions of MAPK and its downstream p70S6K/S6 signaling pathway in the stomach and brain. Moreover, berberine exhibited a similar effect to HL-BX.

CONCLUSIONS

These results indicated that HL-BX promoted gastric motility by regulating brain-gut neurotransmitters through the MAPK signaling pathway. HL-BX and MAPK provide a potential therapeutic option for the treatment of gastroparesis.

Nutrition at the Intersection between Gut Microbiota Eubiosis and Effective Management of Type 2 Diabetes

Nutrition is one of the most influential environmental factors in both taxonomical shifts in gut microbiota as well as in the development of type 2 diabetes mellitus (T2DM). Emerging evidence has shown that the effects of nutrition on both these parameters is not mutually exclusive and that changes in gut microbiota and related metabolites such as short-chain fatty acids (SCFAs) and branched-chain amino acids (BCAAs) may influence systemic inflammation and signaling pathways that contribute to pathophysiological processes associated with T2DM. With this background, our review highlights the effects of macronutrients, carbohydrates, proteins, and lipids, as well as micronutrients, vitamins, and minerals, on T2DM, specifically through their alterations in gut microbiota and the metabolites they produce. Additionally, we describe the influences of common food groups, which incorporate varying combinations of these macronutrients and micronutrients, on both microbiota and metabolic parameters in the context of diabetes mellitus. Overall, nutrition is one of the first line modifiable therapies in the management of T2DM and a better understanding of the mechanisms by which gut microbiota influence its pathophysiology provides opportunities for optimizing dietary interventions.

Dietary novel alkaline protease from Bacillus licheniformis improves broiler meat nutritional value and modulates intestinal microbiota and metabolites

BACKGROUND

Different types of exogenous protease supplements have a positive impact on animal performance, but their effects on the nutritional value of meat and the gut microbial community of broilers have not been extensively studied. The objective of this investigation was to determine the impact of supplementation with a novel alkaline protease derived from Bacillus licheniformis (at doses of 0, 100, 200, 300, and 400 g/t) on the fatty acid and amino acid profiles, inosine monophosphate (IMP) levels, total volatile basic nitrogen (TVB-N) content found within the breast muscle, as well as the impact on the cecal microbiota and metabolites.

RESULTS

Supplementation with 200-400 g/t of the novel protease resulted in a significant elevation in the concentration of essential amino acids (P < 0.001), flavor amino acids (P < 0.001), and total protein (P = 0.013) within the breast muscle. Results derived from the 16S rRNA sequencing and untargeted metabolomics analysis of the cecal content revealed that the novel protease reshaped the cecal microbial and metabolite profiles. In particular, it led to increased relative abundances of Bacteroides, Lactobacillus, Alistipes, and Eubacterium, while simultaneously causing a reduction in the metabolites of D-lactic acid and malonic acid. Moreover, correlation analyses unveiled significant relationships between distinct microbes and metabolites with the contents of IMP, fatty acids, and amino acids in the broiler's breast muscle.

CONCLUSION

In summary, the novel protease regulated the intestinal microbial community and metabolism, thereby inducing changes in the compositions of fatty acids and amino acids profiles, as well as IMP levels in broiler meat. These alterations significantly contributed to the enhancement of the nutritional value and flavor of the meat.

Impact of obesity in asthma: Possible future therapies

Obesity is one of the factors associated with the severity of asthma. Obesity is associated with aggravation of the pathophysiology of asthma, including exacerbations, airway inflammation, decreased pulmonary function, and airway hyperresponsiveness. The present review addresses the characteristics of asthma with obesity, focusing especially on the heterogeneity caused by the degree of type 2 inflammation, sex differences, the onset of asthma, and race differences. To understand the severity mechanisms in asthma and obesity, such as corticosteroid resistance, fatty acids, gut microbiome, and cytokines, several basic research studies are evaluated. Finally, possible future therapies, including weight reduction, microbiome-targeted therapies, and other molecular targeted therapies are addressed. We believe that the present review will contribute to better understanding of the severity mechanisms and the establishment of novel treatments for severe asthma patients with obesity.

High-fat diet-induced gut microbiota alteration promotes lipogenesis by butyric acid/miR-204/ACSS2 axis in chickens

The gut microbiota is known to have significant involvement in the regulation of lipogenesis and adipogenesis, yet the mechanisms responsible for this relationship remain poorly understood. The current study aims to provide insight into the potential mechanisms by which the gut microbiota modulates lipogenesis in chickens. Using chickens fed with a normal-fat diet (NFD, n = 5) and high-fat diet (HFD, n = 5), we analyzed the correlation between gut microbiota, cecal metabolomics, and lipogenesis by 16s rRNA sequencing, miRNA and mRNA sequencing as well as targeted metabolomics analysis. The potential metabolite/miRNA/mRNA axis regulated by gut microbiota was identified using chickens treated with antibiotics (ABX, n = 5). The possible mechanism of gut microbiota regulating chicken lipogenesis was confirmed by fecal microbiota transplantation (FMT) from chickens fed with NFD to chickens fed with HFD (n = 5). The results showed that HFD significantly altered gut microbiota composition and enhanced chicken lipogenesis, with a significant correlation between 3. Furthermore, HFD significantly altered the hepatic miRNA expression profiles and reduced the abundance of hepatic butyric acid. Procrustes analysis indicated that the HFD-induced dysbiosis of the gut microbiota might affect the expression profiles of hepatic miRNA. Specifically, HFD-induced gut microbiota dysbiosis may reduce the abundance of butyric acid and downregulate the expression of miR-204 in the liver. Multiomics analysis identified ACSS2 as a target gene of miR-204. Gut microbiota depletion by an antibiotic cocktail (ABX) showed a gut microbiota-dependent manner in the abundance of butyric acid and the expression of miR-204/ACSS2, which have been observed to be significantly correlated. Fecal microbiota transplantation from NFD chickens into HFD chickens effectively attenuated the HFD-induced excessive lipogenesis, elevated the abundance of butyric acid and the relative expression of miR-204, and reduced the expression of ACSS2 in the liver. Mechanistically, our results showed that the gut microbiota plays an antiobesity role by regulating the butyric acid/miR-204/ACSS2 axis in chickens. This work contributed to a better understanding of the functions of gut microbiota in regulating chicken lipogenesis.

Short-chain fatty acids in diseases

Short-chain fatty acids (SCFAs) are the main metabolites produced by bacterial fermentation of dietary fibre in the gastrointestinal tract. The absorption of SCFAs is mediated by substrate transporters, such as monocarboxylate transporter 1 and sodium-coupled monocarboxylate transporter 1, which promote cellular metabolism. An increasing number of studies have implicated metabolites produced by microorganisms as crucial executors of diet-based microbial influence on the host. SCFAs are important fuels for intestinal epithelial cells (IECs) and represent a major carbon flux from the diet, that is decomposed by the gut microbiota. SCFAs play a vital role in multiple molecular biological processes, such as promoting the secretion of glucagon-like peptide-1 by IECs to inhibit the elevation of blood glucose, increasing the expression of G protein-coupled receptors such as GPR41 and GPR43, and inhibiting histone deacetylases, which participate in the regulation of the proliferation, differentiation, and function of IECs. SCFAs affect intestinal motility, barrier function, and host metabolism. Furthermore, SCFAs play important regulatory roles in local, intermediate, and peripheral metabolisms. Acetate, propionate, and butyrate are the major SCFAs, they are involved in the regulation of immunity, apoptosis, inflammation, and lipid metabolism. Herein, we review the diverse functional roles of this major class of bacterial metabolites and reflect on their ability to affect intestine, metabolic, and other diseases. Video Abstract.

Short-Chain Fatty Acids Alleviate Vancomycin-Caused Humoral Immunity Attenuation in Rabies-Vaccinated Mice by Promoting the Generation of Plasma Cells via Akt-mTOR Pathway

Mounting evidence suggests that gut microbial composition and its metabolites, including short-chain fatty acids (SCFAs), have beneficial effects in regulating host immunogenicity to vaccines. However, it remains unknown whether and how SCFAs improve the immunogenicity of the rabies vaccine. In this study, we investigated the effect of SCFAs on the immune response to rabies vaccine in vancomycin (Vanco)-treated mice and found that oral gavage with butyrate-producing bacteria (C. butyricum) and butyrate supplementation elevated RABV-specific IgM, IgG, and virus-neutralizing antibodies (VNAs) in Vanco-treated mice. Supplementation with butyrate expanded antigen-specific CD4+ T cells and IFN-γ-secreting cells, augmented germinal center (GC) B cell recruitment, promoted plasma cells (PCs) and RABV-specific antibody-secreting cells (ASCs) generation in Vanco-treated mice. Mechanistically, butyrate enhanced mitochondrial function and activated the Akt-mTOR pathway in primary B cells isolated from Vanco-treated mice, ultimately promoting B lymphocyte-induced maturation protein-1 (Blimp-1) expression and CD138+ PCs generation. These results highlight the important role of butyrate in alleviating Vanco-caused humoral immunity attenuation in rabies-vaccinated mice and maintaining host immune homeostasis. IMPORTANCE The gut microbiome plays many crucial roles in the maintenance of immune homeostasis. Alteration of the gut microbiome and metabolites has been shown to impact vaccine efficacy. SCFAs can act as an energy source for B-cells, thereby promoting both mucosal and systemic immunity in the host by inhibiting HDACs and activation of GPR receptors. This study investigates the impact of orally administered butyrate, an SCFA, on the immunogenicity of rabies vaccines in Vanco-treated mice. The results showed that butyrate ameliorated humoral immunity by facilitating the generation of plasma cells via the Akt-mTOR in Vanco-treated mice. These findings unveil the impact of SCFAs on the immune response of the rabies vaccine and confirm the crucial role of butyrate in regulating immunogenicity to rabies vaccines in antibiotic-treated mice. This study provides a fresh insight into the relationship of microbial metabolites and rabies vaccination.

Clostridium butyricum Reduces Obesity in a Butyrate-Independent Way

Accumulating evidence from recent studies links the gut microbiota to obesity, and microbiome therapy has been examined as a treatment. Clostridium butyricum (C. butyricum), an intestinal symbiont, protects the host from a range of diseases. Studies have shown a negative correlation between the relative abundance of C. butyricum and a predisposition for obesity. However, the physiological function and material basis of C. butyricum for obesity are unclear. Here, five C. butyricum isolates were administered to mice on a high-fat diet (HFD) to determine their anti-obesity effects. All isolates suppressed the formation and inflammation of subcutaneous fat, and the two effective strains considerably reduced weight gain and ameliorated dyslipidemia, hepatic steatosis, and inflammation. These positive effects were not achieved by increasing the concentration of intestinal butyrate, and the effective strains could not be replaced by sodium butyrate (NaB). We also discovered that oral supplementation with the two most effective strains changed the metabolism of tryptophan and purine and altered the composition of the gut microbiota. In summary, C. butyricum improved the metabolic phenotypes under the HFD by controlling the composition of the gut microbiota and modulating intestinal metabolites, thereby demonstrating its ability to fight obesity and providing a theoretical foundation for microbial preparations production.

Osteocalcin and Its Potential Functions for Preventing Fatty Liver Hemorrhagic Syndrome in Poultry

Osteocalcin (OCN) is synthesized and secreted by differentiating osteoblasts. In addition to its role in bone, OCN acts as a hormone in the pancreas, liver, muscle, fat, and other organs to regulate multiple pathophysiological processes including glucose homeostasis and adipic acid metabolism. Fat metabolic disorder, such as excessive fat buildup, is related to non-alcoholic fatty liver disease (NAFLD) in humans. Similarly, fatty liver hemorrhage syndrome (FLHS) is a metabolic disease in laying hens, resulting from lipid accumulation in hepatocytes. FLHS affects hen health with significant impact on poultry egg production. Many studies have proposed that OCN has protective function in mammalian NAFLD, but its function in chicken FLHS and related mechanism have not been completely clarified. Recently, we have revealed that OCN prevents laying hens from FLHS through regulating the JNK pathway, and some pathways related to the disease progression have been identified through both in vivo and vitro investigations. In this view, we discussed the current findings for predicting the strategy for using OCN to prevent or reduce FLHS impact on poultry production.

Comparative Gut Microbiome Differences between High and Low Aortic Arch Calcification Score in Patients with Chronic Diseases

Gut dysbiosis can induce chronic inflammation and contribute to atherosclerosis and vascular calcification. The aortic arch calcification (AoAC) score is a simple, noninvasive, and semiquantitative assessment tool to evaluate vascular calcification on chest radiographs. Few studies have discussed the relationship between gut microbiota and AoAC. Therefore, this study aimed to compare the microbiota composition between patients with chronic diseases and high or low AoAC scores. A total of 186 patients (118 males and 68 females) with chronic diseases, including diabetes mellitus (80.6%), hypertension (75.3%), and chronic kidney disease (48.9%), were enrolled. Gut microbiota in fecal samples were analyzed by sequencing of the 16S rRNA gene, and differences in microbial function were examined. The patients were divided into three groups according to AoAC score, including 103 patients in the low AoAC group (AoAC ≤ 3), 40 patients in the medium AoAC group (3 < AoAC ≤ 6), and 43 patients in the high AoAC group (AoAC > 6). Compared to the low AoAC group, the high AoAC group had a significantly lower microbial species diversity (Chao1 index and Shannon index) and increased microbial dysbiosis index. Beta diversity showed that the microbial community composition was significantly different among the three groups (p = 0.041, weighted UniFrac PCoA). A distinct microbial community structure was found in the patients with a low AoAC, with an increased abundance at the genus level of Agathobacter, Eubacterium coprostanoligenes group, Ruminococcaceae UCG-002, Barnesiella, Butyricimonas, Oscillibacter, Ruminococcaceae DTU089, and Oxalobacter. In addition, there was an increased relative abundance of class Bacilli in the high AoAC group. Our findings support the association between gut dysbiosis and the severity of AoAC in patients with chronic diseases.

Improvement in ovarian function following fecal microbiota transplantation from high-laying rate breeders

The underlying mechanism between the gut microbiota and reproductive function is not yet well-known. This study was conducted to investigate the effect of the administration of fecal microbiota transplantation (FMT) from highly laying rate donors on the cecal microbiota, intestinal health and ovarian function in broiler breeders. A total of 60 broiler breeders (53 wk of age) were selected by their laying rate [high (HP, 90.67 ± 0.69%; n = 10) and low (LP, 70.23 ± 0.87%; n = 20)]. The LP breeders were then be transplanted with fecal microbiota from HP hens (FMTHP; n = 10) or the same dosage of PBS (FMTCON; n = 10) for 28 d. The results revealed that FMT from HP donors increased egg-laying rate and serum hormone levels [17β-estradiol (E2), anti-Müller hormone], also decreased proinflammatory cytokine levels (interleukin-6, interleukin-8, tumor necrosis factor-α) of LP breeders (P < 0.05). The FMTHP group breeders had higher villus height, villus height/crypt depth ratio, and upregulated mRNA expression of jejunum barrier-related gene (ZO-2 and mucin-2) and estrogen, follicle-stimulating hormone (FSH) and anti-Müller hormone (AMH) receptor genes (ESR1, ESR2, FSHR, AMHR) (P < 0.05) than FMTCON group. FMT from HP donors led to higher mRNA expression of Bcl2 and sirtuin1 (SIRT1), while it downregulated the proapoptotic genes (Bax, caspase-3, caspase-8, and caspase-9) mRNA expressions in ovary compared with the FMTCON breeders (P < 0.05), and this pattern was also observed in HP donors. Also, HP breeder had higher observed_species and alpha-diversity indexes (Chao1 and ACE) than FMTCON group, while FMTHP can increase observed_species and alpha-diversity indexes (Chao1 and ACE) than FMTCON group (P < 0.05). The bacteria enrichment of Firmicutes (phylum), Bacteroidetes (phylum), Lactobacillus (genus), Enterococcus (genus), and Bacteroides (genus) were increased by FMTHP treatment. The genera Butyricicoccus, Enterococcus, and Lactobacillus were positively correlated with egg-laying rate. Therefore, cecal microbiomes of breeders with high egg-laying performance have more diverse activities, which may be related to the metabolism and health of the host; and FMT from high-yield donors can increase the hormone secretion, intestinal health, and ovarian function to improve egg-laying performance and the SIRT1-related apoptosis and cytokine signaling pathway were involved in this process.

Effect of substitution of taurine for methionine and additional taurine supplementation on the performance and antioxidative capacity of laying hens

Taurine (TAU), a sulfur-containing amino acid that synthesized from methionine and cystine, plays vital roles in maintenance of redox balance. The effect of substitution of TAU for methionine was evaluated in vivo and in vitro. The effects of replacing methionine with TAU and additional TAU supplementation on the performance and antioxidant capacity of laying hens were evaluated. The in vitro cultured chicken primary hepatocytes and intestinal epithelial cells were further employed. Two hubdred eighty-eight 40-wk-old Isa brown laying hens were divided into 4 groups and subjected one to the following treatments: fed with basal diet with 0.17% crystallized DL-Met (CON), the control diet and replace 25% (21% total Met, 21TAU) or 50% (42% total Met, 42TAU) of crystallized DL-Met with taurine, the control diet supplemented with 0.1% taurine (0.1% TAU). The laying rate, feed intake, egg weight, and feed efficiency were not influenced (P > 0.05) by TAU replacement or additional TAU supplementation. In the liver, 0.1% TAU decreased SOD but increased GSH-Px activity (P < 0.01). In duodenum, 42TAU decreased SOD activity (P < 0.05) while 0.1% TAU decreased GSH level and SOD activity (P < 0.05). In the hepatocytes, TAU treatment decreased (P < 0.05) the MDA and GSH contents, whereas increased SOD and GSH-Px activities (P < 0.05). Meanwhile, TAU treatment decreased (P < 0.05) the protein expression of Nrf2 while increase Keap1 expression. The mRNA expression of Nrf2, SOD1, SOD2, CAT, and GCLC were increased (P < 0.05) and GSR were decreased (P < 0.05) by 0.1% TAU. In the intestinal epithelial cells, TAU treatment decreased (P < 0.05) SOD activity, increased (P < 0.05) CAT activity, and decreased (P < 0.05) the mRNA and protein expression of Nrf2. In summary, partial substitution methionine for taurine (21-42%) has no influence on egg performance of hens. Taurine enhances the antioxidative capacity in hepatocyte but not in the enterocytes and if taurine could offer an improved effect on antioxidant capacity needs to be verified under oxidative stress-challenged conditions.

Polysaccharides influence human health via microbiota-dependent and -independent pathways

Polysaccharides are the most diverse molecules and can be extracted from abundant edible materials. Increasing research has been conducted to clarify the structure and composition of polysaccharides obtained from different materials and their effects on human health. Humans can only directly assimilate very limited polysaccharides, most of which are conveyed to the distal gut and fermented by intestinal microbiota. Therefore, the main mechanism underlying the bioactive effects of polysaccharides on human health involves the interaction between polysaccharides and microbiota. Recently, interest in the role of polysaccharides in gut health, obesity, and related disorders has increased due to the wide range of valuable biological activities of polysaccharides. The known roles include mechanisms that are microbiota-dependent and involve microbiota-derived metabolites and mechanisms that are microbiota-independent. In this review, we discuss the role of polysaccharides in gut health and metabolic diseases and the underlying mechanisms. The findings in this review provide information on functional polysaccharides in edible materials and facilitate dietary recommendations for people with health issues. To uncover the effects of polysaccharides on human health, more clinical trials should be conducted to confirm the therapeutic effects on gut and metabolic disease. Greater attention should be directed toward polysaccharide extraction from by-products or metabolites derived from food processing that are unsuitable for direct consumption, rather than extracting them from edible materials. In this review, we advanced the understanding of the structure and composition of polysaccharides, the mutualistic role of gut microbes, the metabolites from microbiota-fermenting polysaccharides, and the subsequent outcomes in human health and disease. The findings provide insight into the proper application of polysaccharides in improving human health.

Dietary γ-Aminobutyric Acid Supplementation Inhibits High-Fat Diet-Induced Hepatic Steatosis via Modulating Gut Microbiota in Broilers

The present study aims to investigate the effect of γ-aminobutyric acid (GABA) on liver lipid metabolism and on AA broilers. Broilers were divided into three groups and fed with low-fat diets, high-fat diets, and high-fat diets supplemented with GABA. Results showed that GABA supplementation decreased the level of triglyceride (TG) in the serum and liver of broilers fed high-fat diets, accompanied by up-regulated mRNA expression of genes related to lipolysis and β-oxidation in the liver (p < 0.05). Furthermore, GABA supplementation increased liver antioxidant capacity, accompanied by up-regulated mRNA expression of antioxidant genes (p < 0.05). 16S rRNA gene sequencing showed that GABA improved high-fat diet-induced dysbiosis of gut microbiota, increased the relative abundance of Bacteroidetes phylum and Barnesiella genus, and decreased the relative abundance of Firmicutes phylum and Ruminococcus_torques_group and Romboutsia genus (p < 0.05). Moreover, GABA supplementation promoted the production of propionic acid and butyric acid in cecal contents. Correlation analysis further suggested the ratio of Firmicutes/Bacteroidetes negatively correlated with hepatic TG content, and positively correlated with cecal short chain fatty acids content (r > 0.6, p < 0.01). Together, these data suggest that GABA supplementation can inhibit hepatic TG deposition and steatosis via regulating gut microbiota in broilers.

A Novel Bacterium, Butyricimonas virosa, Preventing HFD-Induced Diabetes and Metabolic Disorders in Mice via GLP-1 Receptor

Knowledge of the impact of the gut microbiota on human health has increased, and modulation of the bacterial community is now considered a therapeutic target for various diseases. Certain novel bacterial species have probiotic properties associated with improvement in obesity and related metabolic disorders. The relative abundance of Butyricimonas spp. is correlated with metabolic parameters; however, the physiological role of Butyricimonas in metabolic improvement is unclear. In this study, live and heat-killed Butyricimonas virosa were administered to mice with high-fat diet (HFD)-induced obesity. Both live and heat-killed B. virosa ameliorated HFD-impaired body weight, serum glucose level, insulin resistance, and liver steatosis. Moreover, activation of the glucagon-like peptide-1 receptor (GLP-1R) and peroxisome proliferator-activated receptor α (PPARα) was observed in the liver, and the expression levels of insulin receptor substrate (IRS)-1, IRS-2, Toll-like receptor 5 (TLR5), and zonula occludens-1 (ZO-1) were upregulated in the ileum. Finally, we demonstrated that the effect of B. virosa treatment on glucose regulation may be linked to the upregulation of GLP-1R in the liver and is not a result of colonization of the gut by B. virosa or B. virosa-produced butyrate. Our results provide a rationale for the development of Butyricimonas spp.-based therapeutics and prophylactics for hyperglycemia.

Adiponectin Reduces Lipid Content in Chicken Myoblasts by Activating AMPK Signaling Pathway

Studies in mammals have shown that adiponectin is secreted mainly by adipocytes, and it plays a crucial role in glucose and lipid metabolism in muscles. Clarifying the crosstalk role of adiponectin between adipose tissue and skeletal muscle tissue is very important for internal homeostasis. The glucose and lipid metabolism of chicken is different from that of mammals, and the role of adiponectin in chickens is unclear. Therefore, it is of great significance to study the effect and mechanism of adiponectin on lipid metabolism in chickens. In this study, the regulating effect of adiponectin on lipid metabolism in chicken myoblasts was explored by adding a certain concentration of exogenous recombinant adiponectin. Results showed that adiponectin reduced intracellular lipid content, increasing the mRNA expression of adiponectin receptor and cellular uptake of glucose and fatty acids. In addition, adiponectin activated the 5' adenosine monophosphate activated protein kinase (AMPK) signaling pathway. The above results suggested that adiponectin reduced intracellular lipid content, mainly by binding to adiponectin receptor, activating AMPK pathway, increasing cellular uptake of glucose and fatty acids, and promoting lipid oxidation.

Ileal microbial composition in genetically distinct chicken lines reared under normal or high ambient temperatures

Background

Heat stress (HS) has negative effects on poultry productivity, health and welfare resulting in economic losses. Broiler chickens are particularly susceptible to HS due to their high metabolic rate and rapid growth. The commensal intestinal bacterial populations have an important physiological role in the host and could ameliorate the negative effect of HS on the host. Thus, the aim of this study was to compare changes in the ileal (IL) microbiota in four different broiler lines during HS.

Results

Day-old broiler chicks from Giant Jungle Fowl (JF), Athens Canadian Random Bred (ACRB), 1995 Random Bred (L1995), and Modern Random Bred (L2015) lines were raised under thermoneutral (TN) conditions until day (d) 28. On d 29 birds were subjected to TN (24 °C) or chronic cyclic HS (8 h/d, 36 °C) condition till d 56. On d 56 two birds per pen were euthanized, and IL luminal content (IL-L) and mucosal scrapings (IL-M) were collected for bacterial DNA isolation. Libraries were constructed using V3–V4 16S rRNA primers and sequenced using MiSeq. DNA sequences were analyzed using QIIME2 platform and SILVA 132 database for alpha and beta diversity, and taxonomic composition, respectively. Functional property of microbiota was predicted using the PICRUSt 2 pipeline and illustrated with STAMP software. Shannon index was significantly elevated in IL-M under HS. β-diversity PCoA plots revealed separation of microbial community of L2015-TN from JF-TN, JF-HS, ACRB-TN, and ACRB-HS in the IL-M. PERMANOVA analysis showed a significant difference between microbial community of L1995-HS compared to ACRB-HS and JF-TN, L1995-TN compared to ACRB-HS and JF-TN, L2015-HS compared to ACRB-HS and ACRB-TN, L2015-HS compared to JF-TN, L2015-TN compared to ACRB-HS and JF-TN, and ACRB-HS compared to JF-TN in the IL-L. The impact of HS on microbial composition of IL-M was more prominent compared to IL-L with 12 and 2 taxa showing significantly different relative abundance, respectively. Furthermore, differences in microbiota due to the genetic line were more prominent in IL-M than IL-L with 18 and 8 taxa showing significantly different relative abundance, respectively. Unlike taxonomy, predicted function of microbiota was not affected by HS. Comparison of L2015 with JF or ACRB showed significant changes in predicted function of microbiota in both, IL-M and IL-L. Differences were most prominent between L2015 and JF; while there was no difference between L2015 and L1995.

Conclusions

These data indicate the genetic line × temperature effect on the diversity and composition of IL microbiota. Moreover, the data showcase the effect of host genetics on the composition of IL microbiota and their predicted function. These data are of critical importance for devising nutritional strategies to maintain GIT microbial balance and alleviate the negative effects of HS on broiler chickens’ performance and health.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42523-022-00183-y.

Dietary Beta-Hydroxy-Beta-Methyl Butyrate Supplementation Inhibits Hepatic Fat Deposition via Regulating Gut Microbiota in Broiler Chickens

The present study is aimed to explore the effects of different dietary beta-hydroxy-beta-methyl butyrate (HMB) levels (0, 0.05%, 0.10%, or 0.15%) on liver lipid metabolism on Wenshi broiler chickens. Results showed that HMB reduced the liver weight as well as liver concentrations of triacylglycerol (TG) and total cholesterol (TC) (quadratically, p < 0.05), and the lowest values were observed in the 0.10% HMB group. Meanwhile, HMB supplementation significantly altered the expression levels of key genes related to lipid metabolism in the liver of broiler chickens (p < 0.05). Furthermore, 16S rRNA gene sequencing revealed that HMB supplementation could greatly change the richness, diversity, and composition of the broiler gut microbiota, and the Bacteroidetes relative abundance at the phylum level and the Alistipes relative abundance at the genus level were affected (p < 0.05). Correlation analysis further suggested a strong association between Bacteroidetes relative abundance and lipid metabolism-related parameters (p < 0.05). Together, these data suggest that 0.10% HMB supplementation could inhibit hepatic fat deposition via regulating gut microbiota in broilers.

Butyrate-producing human gut symbiont, Clostridium butyricum, and its role in health and disease

Clostridium butyricum is a butyrate-producing human gut symbiont that has been safely used as a probiotic for decades. C. butyricum strains have been investigated for potential protective or ameliorative effects in a wide range of human diseases, including gut-acquired infection, intestinal injury, irritable bowel syndrome, inflammatory bowel disease, neurodegenerative disease, metabolic disease, and colorectal cancer. In this review we summarize the studies on C. butyricum supplementation with special attention to proposed mechanisms for the associated health benefits and the supporting experimental evidence. These mechanisms center on molecular signals (especially butyrate) as well as immunological signals in the digestive system that cascade well beyond the gut to the liver, adipose tissue, brain, and more. The safety of probiotic C. butyricum strains appears well-established. We identify areas where additional human randomized controlled trials would provide valuable further data related to the strains' utility as an intervention.

Effects of Eimeria tenella Infection on Key Parameters for Feed Efficiency in Broiler Chickens

The purpose of the study was to investigate effects of different inoculation dosages of E. tenella on growth performance, gastrointestinal permeability, oocyst shedding, intestinal morphology, fecal consistency, ileal apparent digestibility, antioxidant capacity, and cecal VFA profile in broiler chickens. Five different dosages (T0: 0, T1: 6250, T2: 12,500, T3: 25,000, and T4: 50,000) of E. tenella oocysts were inoculated via oral gavage to fourteen-day-old broilers. Inoculation of E. tenella linearly increased FCR (p < 0.05), and feed intake was quadratically increased on 6 days post-infection (dpi; p = 0.08) and 7 dpi (p = 0.09). Cecal lesion score of each treatment was T0: 0; T1: 0.39 ± 0.14; T2: 0.93 ± 0.21; T3: 1.25 ± 0.16; and T4: 1.58 ± 0.2. Cecal total VFA production was linearly reduced due to E. tenella infection on 6 dpi (p < 0.01). E. tenella infection deepened cecal crypts depth on 6 dpi (CD; p < 0.05). Gastrointestinal permeability tended to be linearly increased (p = 0.07). E. tenella infection tended to linearly reduce duodenal VH (p = 0.1) and jejunal VH on 9 dpi (p = 0.09). Different dosages of E. tenella modulated the tendency of fecal moisture content and oocyst shedding. Therefore, E. tenella infection impaired feed efficiency and small intestinal health mainly by reducing cecal VFA production and deepening cecal CD in broilers.

Resistant starch: Implications of dietary inclusion on gut health and growth in pigs: a review

Starch from cereal grains, pulse grains, and tubers is a major energy substrate in swine rations constituting up to 55% of the diet. In pigs, starch digestion is initiated by salivary and then pancreatic α-amylase, and has as final step the digestion of disaccharides by the brush-border enzymes in the small intestine that produce monosaccharides (glucose) for absorption. Resistant starch (RS) is the proportion of starch that escapes the enzymatic digestion and absorption in the small intestine. The undigested starch reaches the distal small intestine and hindgut for microbial fermentation, which produces short-chain fatty acids (SCFA) for absorption. SCFA in turn, influence microbial ecology and gut health of pigs. These fermentative metabolites exert their benefits on gut health through promoting growth and proliferation of enterocytes, maintenance of intestinal integrity and thus immunity, and modulation of the microbial community in part by suppressing the growth of pathogenic bacteria while selectively enhancing beneficial microbes. Thus, RS has the potential to confer prebiotic effects and may contribute to the improvement of intestinal health in pigs during the post-weaning period. Despite these benefits to the well-being of pigs, RS has a contradictory effect due to lower energetic efficiency of fermented vs. digested starch absorption products. The varying amount and type of RS interact differently with the digestion process along the gastrointestinal tract affecting its energy efficiency and host physiological responses including feed intake, energy metabolism, and feed efficiency. Results of research indicate that the use of RS as prebiotic may improve gut health and thereby, reduce the incidence of post-weaning diarrhea (PWD) and associated mortality. This review summarizes our current knowledge on the effects of RS on microbial ecology, gut health and growth performance in pigs.

The Role of Short-Chain Fatty Acids of Gut Microbiota Origin in Hypertension

Hypertension is a significant risk factor for cardiovascular and cerebrovascular diseases, and its development involves multiple mechanisms. Gut microbiota has been reported to be closely linked to hypertension. Short-chain fatty acids (SCFAs)-the metabolites of gut microbiota-participate in hypertension development through various pathways, including specific receptors, immune system, autonomic nervous system, metabolic regulation and gene transcription. This article reviews the possible mechanisms of SCFAs in regulating blood pressure and the prospects of SCFAs as a target to prevent and treat hypertension.

Butyric and Citric Acids and Their Salts in Poultry Nutrition: Effects on Gut Health and Intestinal Microbiota

Intestinal dysfunction of farm animals, such as intestinal inflammation and altered gut microbiota, is the critical problem affecting animal welfare, performance and farm profitability. China has prohibited the use of antibiotics to improve feed efficiency and growth performance for farm animals, including poultry, in 2020. With the advantages of maintaining gut homeostasis, enhancing digestion, and absorption and modulating gut microbiota, organic acids are regarded as promising antibiotic alternatives. Butyric and citric acids as presentative organic acids positively impact growth performance, welfare, and intestinal health of livestock mainly by reducing pathogenic bacteria and maintaining the gastrointestinal tract (GIT) pH. This review summarizes the discovery of butyric acid (BA), citric acid (CA) and their salt forms, molecular structure and properties, metabolism, biological functions and their applications in poultry nutrition. The research findings about BA, CA and their salts on rats, pigs and humans are also briefly reviewed. Therefore, this review will fill the knowledge gaps of the scientific community and may be of great interest for poultry nutritionists, researchers and feed manufacturers about these two weak organic acids and their effects on intestinal health and gut microbiota community, with the hope of providing safe, healthy and nutrient-rich poultry products to consumers.

Acetate promotes lipogenesis in adipocytes but not in hepatocytes of chickens

1.The role of acetate in lipogenesis of chickens remains largely unknown. This trial investigated the effect of sodium acetate (SA) on chicken fat metabolism via in vivo and in vitro experiments.2.The results indicated that supplementation of SA (1.0 g/kg feed) showed marginal to moderate stimulation on the area of the abdominal fat cells and triglyceride (TG) content in liver and adipose tissues. It increased the transcription of some genes involved in fat synthesis and deposition, but did not affect free fatty acid receptor 2 (FFAR2) expression in either liver or abdominal fat.3. In cultured hepatocytes treated with 0.01 mM to 5 mM SA, although mRNA levels of ACC1, PPAR, SREBP-1 c, and FFAR2 were upregulated with SA at certain concentrations, TG content and protein expression of lipogenic genes and FFAR2 were not altered at any dosages. In adipogenic differentiation of preadipocytes, high concentrations of SA (5 mM) exhibited significant increments in TG content and accumulated fat droplets, associated with stimulated transcription of FAS, LPL, AD, FABP4, and FFAR2, as well as elevated protein expression of FABP4 and FFAR2.4. The results showed that adipocytes were more sensitive to acetate than hepatocytes in chickens. While acetate played a minor role in hepatic fat metabolism, it promoted lipogenesis in adipocytes via FFAR2 with the involvement of FAS, LPL, and FABP4.

Lacticaseibacillus rhamnosus Reduces the Pathogenicity of Escherichia coli in Chickens

Lacticaseibacillus rhamnosus is a recognized probiotic that is widely used in scientific research and clinical applications. This study found that the Lacticaseibacillus rhamnosus GG (LGG) strain can reduce the adhesion of Escherichia coli (E. coli) to primary chicken intestinal epithelial cells by 75.7% and inhibit 41.7% of the E. coli that adhere to intestinal epithelial cells. Additionally, LGG showed strong inhibitory ability on the growth of E. coli, Staphylococcus aureus, Salmonella Paratyphi B, and Salmonella Enteritidis in vitro. Furthermore, the influence of LGG on the growth performance, intestinal flora, immunity, and disease resistance of chickens was explored. Chickens fed with LGG exhibited increased average daily weight gain and concentrations of sIgA, IgG, and IgM than did controls. After 21 days of feeding, a diet with LGG increased the diversity of intestinal microbiota and maintained intestinal health. Moreover, LGG promoted immunologic barriers by upregulating cytokines and chemokines via the Toll-like receptor. The major pro-inflammatory factors, including Myd88, NF-κB, Il6, and Il8, were upregulated compared to controls. After being challenged with E. coli, the survival rate of chickens fed with LGG was significantly higher than those in the control group, and decreased numbers of E. coli were detected in the heart and lungs of the LGG group. In summary, oral administration of LGG to chickens could improve growth performance, maintain intestinal homeostasis, and enhance innate immune response and disease resistance.

Bacillus amyloliquefaciens ameliorates high-carbohydrate diet-induced metabolic phenotypes by restoration of intestinal acetate-producing bacteria in Nile Tilapia

Poor utilisation efficiency of carbohydrate always leads to metabolic phenotypes in fish. The intestinal microbiota plays an important role in carbohydrate degradation. Whether the intestinal bacteria could alleviate high-carbohydrate diet (HCD)-induced metabolic phenotypes in fish remains unknown. Here, a strain affiliated to Bacillus amyloliquefaciens was isolated from the intestine of Nile tilapia. A basal diet (CON), HCD or HCD supplemented with B. amy SS1 (HCB) was used to feed fish for 10 weeks. The beneficial effects of B. amy SS1 on weight gain and protein accumulation were observed. Fasting glucose and lipid deposition were decreased in the HCB group compared with the HCD group. High-throughput sequencing showed that the abundance of acetate-producing bacteria was increased in the HCB group relative to the HCD group. Gas chromatographic analysis indicated that the concentration of intestinal acetate was increased dramatically in the HCB group compared with that in the HCD group. Glucagon-like peptide-1 was also increased in the intestine and serum of the HCB group. Thus, fish were fed with HCD, HCD supplemented with sodium acetate at 900 mg/kg (HLA), 1800 mg/kg (HMA) or 3600 mg/kg (HHA) diet for 8 weeks, and the HMA and HHA groups mirrored the effects of B. amy SS1. This study revealed that B. amy SS1 could alleviate the metabolic phenotypes caused by HCD by enriching acetate-producing bacteria in fish intestines. Regulating the intestinal microbiota and their metabolites might represent a powerful strategy for fish nutrition modulation and health maintenance in future.

The Gut Microbiome and Ozone-induced Airway Hyperresponsiveness. Mechanisms and Therapeutic Prospects

In recent years, several new asthma therapeutics have been developed. Although many of these agents show promise in treating allergic asthma, they are less effective against nonallergic forms of asthma. The gut microbiome has important roles in human health and disease, and a growing body of evidence indicates a link between the gut microbiome and asthma. Here, we review those data focusing on the role of the microbiome in mouse models of nonallergic asthma including obese asthma and asthma triggered by exposure to air pollutants. We describe the impact of antibiotics, diet, and early life events on airway responses to the air pollutant ozone, including in the setting of obesity. We also review potential mechanisms responsible for gut-lung interactions focusing on bacterial-derived metabolites, the immune system, and hormones. Finally, we discuss future prospects for gut microbiome-targeted therapies such as fecal microbiome transplantation, prebiotics, probiotics, and prudent use of antibiotics. Better understanding of the role of the microbiome in airway responses may lead to exploration of new microbiome-targeted therapies to control asthma, especially nonallergic forms of asthma.

GPCRs get fatty: the role of G protein-coupled receptor signaling in the development and progression of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD), characterized by the abnormal deposition of lipids within the liver not due to alcohol consumption, is a growing epidemic affecting over 30% of the United States population. Both simple fatty liver and its more severe counterpart, nonalcoholic steatohepatitis, represent one of the most common forms of liver disease. Recently, several G protein-coupled receptors have emerged as targets for therapeutic intervention for these disorders. These include those with known hepatic function as well as those involved in global metabolic regulation. In this review, we highlight these emerging therapeutic targets, focusing on several common themes including their activation by microbial metabolites, stimulatory effect on insulin and incretin secretion, and contribution to glucose tolerance. The overlap in ligands, localization, and downstream effects of activation indicate the interdependent nature of these receptors and highlight the importance of this signaling family in the development and prevention of NAFLD.

The Protective Role of Butyrate against Obesity and Obesity-Related Diseases

Worldwide obesity is a public health concern that has reached pandemic levels. Obesity is the major predisposing factor to comorbidities, including type 2 diabetes, cardiovascular diseases, dyslipidemia, and non-alcoholic fatty liver disease. The common forms of obesity are multifactorial and derive from a complex interplay of environmental changes and the individual genetic predisposition. Increasing evidence suggest a pivotal role played by alterations of gut microbiota (GM) that could represent the causative link between environmental factors and onset of obesity. The beneficial effects of GM are mainly mediated by the secretion of various metabolites. Short-chain fatty acids (SCFAs) acetate, propionate and butyrate are small organic metabolites produced by fermentation of dietary fibers and resistant starch with vast beneficial effects in energy metabolism, intestinal homeostasis and immune responses regulation. An aberrant production of SCFAs has emerged in obesity and metabolic diseases. Among SCFAs, butyrate emerged because it might have a potential in alleviating obesity and related comorbidities. Here we reviewed the preclinical and clinical data that contribute to explain the role of butyrate in this context, highlighting its crucial contribute in the diet-GM-host health axis.

Different effects of probiotics and antibiotics on the composition of microbiota, SCFAs concentrations and FFAR2/3 mRNA expression in broiler chickens

AIMS

The aims of this study were to investigate the effects of probiotics and antibiotics on microbial composition, short chain fatty acids (SCFAs) concentration and free fatty acid receptor 2/3 (FFAR2/3) expression in boiler chickens.

METHODS AND RESULTS

A total of 150 1-day-old male broilers were randomly allocated into three groups, control (CON) group, probiotics (PB) group and antibiotics (ATB) group. Results indicated that PB improved the average body weight from 1 to 21 days and feed intake from 21 to 42 days (P < 0·05), while ATB improved the feed efficiency from 1 to 42 days (P < 0·05). Based on 16s rRNA sequencing, PB treatment increased the amount of kingdom bacteria, and the relative abundance of the main bacteria including acetate and butyrate producing bacteria of phylum Firmicutes, family Ruminococcaceae and genus Faecalibacterium. ATB treatment also increased the relative abundance of phylum Firmicutes, family Ruminococcaceae and Lachnospiraceae, however, it introduced some pathogenic bacteria, such as bacteria of family Rikenellaceae and Enterobacteriaceae. Gas chromatography and mass spectrometry (GC-MS) assay revealed that PB increased acetate and butyrate concentrations at both 21 and 42 days, and propionate at 42 days in the colorectum. Moreover qRT-PCR analysis showed PB treatment significantly activated the FFAR2/3 mRNA expressions. On the contrast, ATB treatment lowered the colorectal propionate at 21 days, and decreased acetate, propionate and butyrate concentrations at 42 days, accompanied with decreased FFAR2/3 mRNA expressions.

CONCLUSIONS

Compared to the CON birds, an enriched SCFAs producing bacteria with higher SCFAs contents and activated FFAR2/3 expressions are prominent features of PB birds. However, antibiotics treatment plays the reverse effect compared to PB treatment.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study brings a significant idea that less SCFAs concentration may be another reason why the antibiotics inhibit the immune system development and immunity of the body.

Propionate inhibits fat deposition via affecting feed intake and modulating gut microbiota in broilers

As one of the 3 main short-chain fatty acids, the role of propionate in chicken fat metabolism is largely unknown. In this study, we demonstrated that dietary supplementation of coated sodium propionate (SP) moderately inhibits fat deposition in broiler chickens, as evidenced by the decreased adipocyte mean area (P < 0.01), the lowered triglyceride content in abdominal fat tissue (P < 0.01), and the reduced transcription of several lipogenic genes in liver and abdominal fat tissues (P < 0.05). Surprisingly, the propionate content was not significantly elevated either in serum or in the cecal chyme by SP administration (P > 0.05). However, SP application significantly decreased the average daily feed intake of broilers (P < 0.05). In addition, the composition of the cecal microbial communities was altered, with the ratio of Firmicutes to Bacteroidetes decreasing in particular (P < 0.05). At the genus level, SP application increased the richness of Alistipes, Lactobacillus, and Bifidobacterium, while reduced the abundance of Lachnospiraceae and Helicobacter significantly (P < 0.05). Moreover, in vitro experiments indicated that, although physiological concentrations of propionate (0.01 to 0.1 mmol) upregulated or downregulated the transcription of some fat synthesis-associated genes (P < 0.05), they did not significantly affect the triglyceride accumulation in hepatocytes and adipocytes (P > 0.05). These results suggest that feed supplementation with SP inhibits fat deposition in broilers by reducing feed and caloric intake, but not via direct regulation on hepatic fat synthesis or adipocytic fat deposition. Alteration in the relative populations of the gut microflora suggests that SP may have gut health implications.

Internalization-Dependent Free Fatty Acid Receptor 2 Signaling Is Essential for Propionate-Induced Anorectic Gut Hormone Release

The ability of propionate, a short-chain fatty acid produced from the fermentation of non-digestible carbohydrates in the colon, to stimulate the release of anorectic gut hormones, such as glucagon like peptide-1 (GLP-1), is an attractive approach to enhance appetite regulation, weight management, and glycemic control. Propionate induces GLP-1 release via its G protein-coupled receptor (GPCR), free fatty acid receptor 2 (FFA2), a GPCR that activates Gαi and Gαq/11. However, how pleiotropic GPCR signaling mechanisms in the gut regulates appetite is poorly understood. Here, we identify propionate-mediated G protein signaling is spatially directed within the cell whereby FFA2 is targeted to very early endosomes. Furthermore, propionate activates a Gαi/p38 signaling pathway, which requires receptor internalization and is essential for propionate-induced GLP-1 release in enteroendocrine cells and colonic crypts. Our study reveals that intestinal metabolites engage membrane trafficking pathways and that receptor internalization could orchestrate complex GPCR pathways within the gut.

Influence of level of inclusion of Azolla leaf meal on growth performance, meat quality and skeletal muscle p70S6 kinase α abundance in broiler chickens

The interest in biodiesel production from oil-bearing seeds rather than soybean necessitates the scientific validation of other good quality protein sources that could substitute soybean meal in animal diets, particularly, broiler chickens where soybean meal constitutes a large portion of their diet. Therefore, the present study was conducted to investigate the effect of sun-dried Azolla leaf meal (ALM) as an unconventional dietary protein source in broiler chicken diet on growth performance, meat quality, skeletal muscle cell growth and protein synthesis through regulation of ribosomal protein S6 kinase (p70S6 kinase α). A total of 120 male Ross 308 broiler chicks were randomly allocated to three dietary treatments. Each treatment had four cages (i.e. replicates) with 10 birds/cage. The control group was fed with a corn-soy-based diet, the AZ5 group was supplemented with 5% ALM and the AZ10 group was supplemented with 10% ALM for 37 days. A 5-day trial was also conducted to measure the apparent nutrient digestibility. Growth performance parameters were measured weekly. At the end of the experiment, 12 birds from each group (3/cage) were euthanized and used for samplings. Inclusion of ALM tended to improve BW gain (P = 0.06) and increased feed intake (P < 0.01). Additionally, ALM decreased the percentage of breast meat cooking loss linearly (P < 0.01). In addition, ALM at a dose of 5% increased the production of propionate in the cecum (P = 0.01). Activation of breast muscle p70S6 kinase was higher when ALM was included in a dose-dependent manner (P < 0.01). The inclusion of ALM increased breast meat redness (P < 0.01); however, the lightness was within the normal range in all groups. Findings from our study suggest that ALM could be included in a broiler chicken diet up to 5% without any major negative effect on meat quality or performance, and it regulates muscle protein synthesis through activation of mammalian target of rapamycin/6S kinase signaling.

The Gut Microbiota of Laying Hens and Its Manipulation with Prebiotics and Probiotics To Enhance Gut Health and Food Safety

The microbiota plays a vital role in maintaining gut health and influences the overall performance of chickens. Most gut microbiota-related studies have been performed in broilers, which have different microbial communities compared to those of layers. The normal gut microbiota of laying chickens is dominated by Proteobacteria, Firmicutes, Bacteroidetes, Fusobacteria, and Actinobacteria at the phylum level. The composition of the gut microbiota changes with chicken age, genotype, and production system. The metabolites of gut microbiota, such as short-chain fatty acids, indole, tryptamine, vitamins, and bacteriocins, are involved in host-microbiota cross talk, maintenance of barrier function, and immune homeostasis. Resident gut microbiota members also limit and control the colonization of foodborne pathogens. In-feed supplementations of prebiotics and probiotics strengthen the gut microbiota for improved host performance and colonization resistance to gut pathogens, such as Salmonella and Campylobacter The mechanisms of action of prebiotics and probiotics come through the production of organic acids, activation of the host immune system, and production of antimicrobial agents. Probiotic candidates, including Lactobacillus, Bifidobacterium, Bacillus, Saccharomyces, and Faecalibacterium isolates, have shown promising results toward enhancing food safety and gut health. Additionally, a range of complex carbohydrates, including mannose oligosaccharides, fructo-oligosaccharides, and galacto-oligosaccharides, and inulin are promising candidates for improving gut health. Here, we review the potential roles of prebiotics and probiotics in the reshaping of the gut microbiota of layer chickens to enhance gut health and food safety.

Salmonella Typhimurium infection disrupts but continuous feeding of Bacillus based probiotic restores gut microbiota in infected hens

Background

The gut microbiota plays an important role in the colonisation resistance and invasion of pathogens. Salmonella Typhimurium has the potential to establish a niche by displacing the microbiota in the chicken gut causing continuous faecal shedding that can result in contaminated eggs or egg products. In the current study, we investigated the dynamics of gut microbiota in laying chickens during Salmonella Typhimurium infection. The optimisation of the use of an infeed probiotic supplement for restoration of gut microbial balance and reduction of Salmonella Typhimurium load was also investigated.

Results

Salmonella infection caused dysbiosis by decreasing (FDR < 0.05) the abundance of microbial genera, such as Blautia, Enorma, Faecalibacterium, Shuttleworthia, Sellimonas, Intestinimonas and Subdoligranulum and increasing the abundance of genera such as Butyricicoccus, Erysipelatoclostridium, Oscillibacter and Flavonifractor. The higher Salmonella Typhimurium load resulted in lower (P < 0.05) abundance of genera such as Lactobacillus, Alistipes, Bifidobacterium, Butyricimonas, Faecalibacterium and Romboutsia suggesting Salmonella driven gut microbiota dysbiosis. Higher Salmonella load led to increased abundance of genera such as Caproiciproducens, Acetanaerobacterium, Akkermansia, Erysipelatoclostridium, Eisenbergiella, EscherichiaShigella and Flavonifractor suggesting a positive interaction of these genera with Salmonella in the displaced gut microbiota. Probiotic supplementation improved the gut microbiota by balancing the abundance of most of the genera displaced by the Salmonella challenge with clearer effects observed with continuous supplementation of the probiotic. The levels of acetate and butyrate in the faeces were not affected (P > 0.05) by Salmonella challenge and the butyrate level was increased by the continuous feeding of the probiotic. Probiotic supplementation in Salmonella challenged chickens resulted in higher level of propionate. Continuous probiotic supplementation decreased (P < 0.05) the overall mean load of Salmonella in faeces and had a significant effect on Salmonella load reduction in internal organs.

Conclusions

Salmonella challenge negatively impacts the diversity and abundance of many gut microbial genera involved in important functions such as organic acid and vitamin production. Strategic feeding of a Bacillus based probiotic helps in restoring many of the microbial genera displaced by Salmonella Typhimurium challenge.

Characteristics of the fecal microbiota of high- and low-yield hens and effects of fecal microbiota transplantation on egg production performance

The microbiota that resides in the digestive tract plays pivotal role in maintaining intestinal environmental stability by promoting nutrition digestion and intestinal mucosal immunity. However, whether the intestinal microbiota in laying hens affects egg laying- performance is not known. In this study, 16S rDNA gene sequencing and fecal microbiota transplantation were used to determine the structure of the intestinal microbiota and the effect of the intestinal microbiota on egg production. The results revealed that Firmicutes were dominant in both the H (high egg laying rates) and L (low egg laying rates) groups, while Bacteroides, Actinobacteria and Proteobacteria were significantly enriched in the L group compared to the H group. The laying rates were weakly affected in H hens transplanted with the fecal microbiota from L hens, except for temporary fluctuation, while the egg laying rates were significantly increased in L hens transplanted with the fecal microbiota from H hens. Therefore, we concluded that the population structure of the intestinal microbiota varied between the H and L groups, and the intestinal microbiota of high-yield laying hens had significant effects on low-yield laying hens performance.

The Timing Effects of Soy Protein Intake on Mice Gut Microbiota

Soy protein intake is known to cause microbiota changes. While there are some reports about the effect of soy protein intake on gut microbiota and lipid metabolism, effective timing of soy protein intake has not been investigated. In this study, we examined the effect of soy protein intake timing on microbiota. Mice were fed twice a day, in the morning and evening, to compare the effect of soy protein intake in the morning with that in the evening. Mice were divided into three groups: mice fed only casein protein, mice fed soy protein in the morning, and mice fed soy protein in the evening under high-fat diet conditions. They were kept under the experimental condition for two weeks and were sacrificed afterward. We measured cecal pH and collected cecal contents and feces. Short-chain fatty acids (SCFAs) from cecal contents were measured by gas chromatography. The microbiota was analyzed by sequencing 16S rRNA genes from feces. Soy protein intake whether in the morning or evening led to a greater microbiota diversity and a decrease in cecal pH resulting from SCFA production compared to casein intake. In addition, these effects were relatively stronger by morning soy protein intake. Therefore, soy protein intake in the morning may have relatively stronger effects on microbiota than that in the evening.