The effects of the supplementation of multi-strain probiotics on intestinal microbiota, metabolites and inflammation of young SPF chickens challenged with Salmonella enterica subsp. enterica

The effect of peanut skins as a natural antimicrobial feed additive on ileal and cecal microbiota in broiler chickens inoculated with Salmonella enterica Enteritidis

The consumption of poultry products contaminated with Salmonella species is one of the most common causes of Salmonella infections. In vivo studies demonstrated the potential application of peanut skins (PS) as an antimicrobial poultry feed additive to help mitigate the proliferation of Salmonella in poultry environments. Tons of PS, a waste by-product of the peanut industry, are generated and disposed in U.S. landfills annually. Peanut skins and extracts have been shown to possess antimicrobial and antioxidant properties. Hence, we aimed to determine the effect of PS as a feed additive on the gut microbiota of broilers fed a control or PS supplemented (4% inclusion) diet and inoculated with or without Salmonella enterica Enteritidis (SE). At hatch 160 male broilers were randomly assigned to 4 treatments: 1) CON-control diet without SE, 2) PS-PS diet without SE, 3) CONSE-control diet with SE, 4) PSSE-PS diet with SE. On d 3, birds from CONSE and PSSE treatments were inoculated with 4.2 × 109 CFU/mL SE. At termination (4 wk), 10 birds/treatment were euthanized and ileal and cecal contents were collected for 16S rRNA analysis using standard methodologies. Sequencing data were analyzed using QIIME2. No effect of PS or SE was observed on ileal alpha and beta diversity, while evenness, richness, number of amplicon sequence variants (ASV) and Shannon, as well as beta diversity were significantly (P < 0.05) affected in ceca. Similarly, more differentially abundant taxa between treatment groups were identified in ceca than in ileum. However, more microbiota functional changes, based on the PICRUST2 prediction, were observed in ileum. Overall, relatively minor changes in microbiota were observed during SE infection and PS treatment, suggesting that PS addition may not attenuate the SE proliferation, as shown previously, through modulation of microbiota in gastrointestinal tract. However, while further studies are warranted, these results suggest that PS may potentially serve as a functional feed additive for poultry for improvement of animal health.

Influence of Pediococcus pentosaceus GT001 on Performance, Meat Quality, Immune Function, Antioxidant and Cecum Microbial in Broiler Chickens Challenged by Salmonella typhimurium

This study evaluated the effects of Pediococcus pentosaceus GT001 on Salmonella typhimurium (S. typhimurium)-challenged broiler chickens. Two hundred Ross 708 broiler day-old chicks with comparable weight were distributed at random into four treatments with five replicates and ten chicks per replicate. The following were the treatment groups: (B) basal diet (control); (B + S) basal diet and birds were challenged with S. typhimurium at 1.0 × 107 cfu/g; (B + P) basal diet + Pediococcus pentosaceus GT001 at 4.0 × 108 cfu/g; (B + P + S) basal diet + P. pentosaceus GT001 at 4.0 × 108 cfu/g and birds were challenged with S. typhimurium at 1.0 × 107 cfu/g. There was a significant reduction (p < 0.05) in the body weight of the Salmonella-infected birds compared to the other treatment groups. However, the FCRs of the broilers were comparable among the different treatment groups (p > 0.05). The lipid profile and liver function indices measured were significantly enhanced in the P. pentosaceus GT001-supplemented groups (B + P and B + P + S) compared to the group that was Salmonella-challenged (p < 0.05) but were similar to those in the control group. The serum antioxidant activities, such as the T-AOC, SOD, CAT, GHS-Px and MDA, were significantly improved in the P. pentosaceus GT001-supplemented groups (B + P and B + P + S) (p < 0.05). The MDA was similar in the B + P and B + P + S groups, but both were significantly lower than the control and the Salmonella groups. The administration of P. pentosaceus GT001 enhanced the lipase and amylase levels in both the serum and intestine of the broilers (p < 0.05). The immunoglobin (IgA, IgG, IgM) and cytokine (IL-10 and IL-6) levels in the serum were significantly higher in the B, B + P and B + P + S treatment groups (p < 0.05). The immune-related organs (bursa and spleen) were significantly influenced in the birds fed with P. pentosaceus GT001. No significant variation was noted among all the dietary treatments in terms of the measured meat quality indices. The small intestinal digesta content of the Salmonella load was below a detectable range after 14 days of infection (p < 0.05). No significant differences were observed among the different treatment groups in terms of the breast pH, drip loss and meat color (p > 0.05). The inclusion of P. pentosaceus GT001 also modified the community structure in the cecum. This indicates that it has health benefits and could be incorporated in the broiler diet.

Salmonella spp. in poultry production-A review of the role of interventions along the production continuum

Salmonella is a significant pathogen of human and animal health and poultry are one of the most common sources linked with foodborne illness worldwide. Global production of poultry meat and products has increased significantly over the last decade or more as a result of consumer demand and the changing demographics of the world's population, where poultry meat forms a greater part of the diet. In addition, the relatively fast growth rate of birds which is significantly higher than other meat species also plays a role in how poultry production has intensified. In an effort to meet the greater demand for poultry meat and products, modern poultry production and processing practices have changed and practices to target control and reduction of foodborne pathogens such as Salmonella have been implemented. These strategies are implemented along the continuum from parent and grandparent flocks to breeders, the farm and finished broilers to transport and processing and finally from retail to the consumer. This review focuses on common practices, interventions and strategies that have potential impact for the control of Salmonella along the poultry production continuum from farm to plate.

Recent Trends on Mitigative Effect of Probiotics on Oxidative-Stress-Induced Gut Dysfunction in Broilers under Necrotic Enteritis Challenge: A Review

Gut health includes normal intestinal physiology, complete intestinal epithelial barrier, efficient immune response, sustained inflammatory balance, healthy microbiota, high nutrient absorption efficiency, nutrient metabolism, and energy balance. One of the diseases that causes severe economic losses to farmers is necrotic enteritis, which occurs primarily in the gut and is associated with high mortality rate. Necrotic enteritis (NE) primarily damages the intestinal mucosa, thereby inducing intestinal inflammation and high immune response which diverts nutrients and energy needed for growth to response mediated effects. In the era of antibiotic ban, dietary interventions like microbial therapy (probiotics) to reduce inflammation, paracellular permeability, and promote gut homeostasis may be the best way to reduce broiler production losses. The current review highlights the severity effects of NE; intestinal inflammation, gut lesions, alteration of gut microbiota balance, cell apoptosis, reduced growth performance, and death. These negative effects are consequences of; disrupted intestinal barrier function and villi development, altered expression of tight junction proteins and protein structure, increased translocation of endotoxins and excessive stimulation of proinflammatory cytokines. We further explored the mechanisms by which probiotics mitigate NE challenge and restore the gut integrity of birds under disease stress; synthesis of metabolites and bacteriocins, competitive exclusion of pathogens, upregulation of tight junction proteins and adhesion molecules, increased secretion of intestinal secretory immunoglobulins and enzymes, reduction in pro-inflammatory cytokines and immune response and the increased production of anti-inflammatory cytokines and immune boost via the modulation of the TLR/NF-ĸ pathway. Furthermore, increased beneficial microbes in the gut microbiome improve nutrient utilization, host immunity, and energy metabolism. Probiotics along with biosecurity measures could mitigate the adverse effects of NE in broiler production.

Long-chain glucomannan supplementation modulates immune responsiveness, as well as intestinal microbiota, and impacts infection of broiler chickens with Salmonella enterica serotype Enteritidis

The zoonotic pathogen Salmonella enterica serotype Enteritidis (SE) causes severe disease in young chickens. Restriction on antibiotic use requires alternative SE control strategies such as nutritional solutions to improve the resistance of chickens. In this study, chickens were fed long-chain glucomannan (GM) or standard diet and challenged with SE at seven days of age. During 21 days post-infection (dpi), we determined numbers and responsiveness of natural killer (NK) and T cells in ileum and spleen, and SE-specific antibody titers in serum. Microbiota compositions in ileum and caeca were determined, as well as correlations of these with numbers and function of immune cells. Some of the samples in the control group had numerically higher CFUs than the GM-treated group. In addition, the relative abundance of SE based on DNA assessment was significantly lower at 21 dpi upon GM supplementation. At 3 dpi, numbers of intraepithelial NK cells were significantly higher, while activation of intraepithelial NK cells (7 dpi), numbers of intraepithelial cytotoxic CD8⁺ T cells (14 dpi) and SE-specific antibodies (14 dpi) were numerically higher. Furthermore, relative abundance of the commensal lactic acid bacteria (LAB) significantly increased with GM supplementation post-infection. Higher relative abundance of streptococci was associated with reduced SE in ileal and caecal contents at 21 dpi. Relative abundance of streptococci negatively correlated with SE counts and positively correlated with NK cell activation and SE-specific antibodies, which suggests involvement of the commensal LAB in NK cell responsiveness. These results indicate that GM supplementation modulates the immune system, intestinal microbiota and impacts SE infection of young chickens.

Copper/Zinc-Modified Palygorskite Protects Against Salmonella Typhimurium Infection and Modulates the Intestinal Microbiota in Chickens

Palygorskite (Pal), a clay nanoparticle, has been demonstrated to be a vehicle for drug delivery. Copper has antibacterial properties, and zinc is an essential micronutrient for intestinal health in animals and humans. However, whether copper/zinc-modified Pal (Cu/Zn-Pal) can protect chickens from Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) infection remains unclear. In this study, three complexes (Cu/Zn-Pal-1, Cu/Zn-Pal-2, and Cu/Zn-Pal-3) were prepared, and Cu/Zn-Pal-1 was shown to be the most effective at inhibiting the growth of S. Typhimurium in vitro, whereas natural Pal alone had no inhibitory effect. In vivo, Cu/Zn-Pal-1 reduced S. Typhimurium colonization in the intestine of infected chickens and relieved S. Typhimurium-induced organ and intestinal mucosal barrier damage. Moreover, this reduction in Salmonella load attenuated intestinal inflammation and the oxidative stress response in challenged chickens. Additionally, Cu/Zn-Pal-1 modulated the intestinal microbiota in infected chickens, which was characterized by the reduced abundance of Firmicutes and the increased abundance of Proteobacteria and Bacteroidetes. Our results indicated that the Cu/Zn-Pal-1 complex may be an effective feed supplement for reducing S. Typhimurium colonization of the gut.

Progress on Gut Health Maintenance and Antibiotic Alternatives in Broiler Chicken Production

The perturbation of gut health is a common yet unresolved problem in broiler chicken production. Antibiotics used as growth promoters have remarkably improved the broiler production industry with high feed conversion efficiency and reduced intestinal problems. However, the misuse of antibiotics has also led to the increase in the development of antibiotic resistance and antibiotic residues in the meat. Many countries have enacted laws prohibiting the use of antibiotics in livestock production because of the increasing concerns from the consumers and the public. Consequently, one of the most significant discussions in the poultry industry is currently antibiotic-free livestock production. However, the biggest challenge in animal husbandry globally is the complete removal of antibiotics. The necessity to venture into antibiotic-free production has led researchers to look for alternatives to antibiotics in broiler chicken production. Many strategies can be used to replace the use of antibiotics in broiler farming. In recent years, many studies have been conducted to identify functional feed additives with similar beneficial effects as antibiotic growth promoters. Attention has been focused on prebiotics, probiotics, organic acids, emulsifiers, enzymes, essential oils, tributyrin, and medium-chain fatty acids. In this review, we focused on recent discoveries on gut health maintenance through the use of these functional feed additives as alternatives to antibiotics in the past 10 years to provide novel insights into the design of antibiotic-free feeds.

Biological Function of Short-Chain Fatty Acids and Its Regulation on Intestinal Health of Poultry

Short-chain fatty acids (SCFAs) are metabolites generated by bacterial fermentation of dietary fiber (DF) in the hindgut. SCFAs are mainly composed of acetate, propionate and butyrate. Many studies have shown that SCFAs play a significant role in the regulation of intestinal health in poultry. SCFAs are primarily absorbed from the intestine and used by enterocytes as a key substrate for energy production. SCFAs can also inhibit the invasion and colonization of pathogens by lowering the intestinal pH. Additionally, butyrate inhibits the expression of nitric oxide synthase (NOS), which encodes inducible nitric oxide synthase (iNOS) in intestinal cells via the PPAR-γ pathway. This pathway causes significant reduction of iNOS and nitrate, and inhibits the proliferation of Enterobacteriaceae to maintain overall intestinal homeostasis. SCFAs can enhance the immune response by stimulating cytokine production (e.g. TNF-α, IL-2, IL-6, and IL-10) in the immune cells of the host. Similarly, it has been established that SCFAs promote the differentiation of T cells into T regulatory cells (Tregs) and expansion by binding to receptors, such as Toll-like receptors (TLR) and G protein-coupled receptors (GPRs), on immune cells. SCFAs have been shown to repair intestinal mucosa and alleviate intestinal inflammation by activating GPRs, inhibiting histone deacetylases (HDACs), and downregulating the expression of pro-inflammatory factor genes. Butyrate improves tight-junction-dependent intestinal barrier function by promoting tight junction (TJ) assembly. In recent years, the demand for banning antibiotics has increased in poultry production. Therefore, it is extremely important to maintain the intestinal health and sustainable production of poultry. Taking nutrition strategies is important to regulate SCFA production by supplementing dietary fiber and prebiotics, SCFA-producing bacteria (SPB), and additives in poultry diet. However, excessive SCFAs will lead to the enteritis in poultry production. There may be an optimal level and proportion of SCFAs in poultry intestine, which benefits to gut health of poultry. This review summarizes the biological functions of SCFAs and their role in gut health, as well as nutritional strategies to regulate SCFA production in the poultry gut.

Bacillus subtilis BSH has a protective effect on Salmonella infection by regulating the intestinal flora structure in chickens

Salmonellosis is a worldwide zoonotic disease that poses a serious threat to the reproduction of livestock and poultry and the health of young animals. Probiotics including Bacillus species, have received increasing attention as a substitute for antibiotics. In this study, chicks infected with Salmonella were fed feed supplemented with the BSH to observe the pathological changes in the liver, detect the number of viable bacteria in the liver and spleen, and record the death of the chicks. The results showed that BSH could reduce the pathological changes in the liver and the invasion of Salmonella into the liver and spleen of chicks. In addition, the survival rate of chicks in the BSH experimental group was 60%, while that in the infected control group was 26%, indicating that BSH had a protective effect on chicks infected with Salmonella. Finally, the fecal microflora of 9-day-old chicks was analyzed by 16S rRNA high-throughput sequencing. The results showed that Salmonella infection could cause intestinal flora changes, while BSH could alleviate this change. In addition, BSH also promoted the proliferation of Lactobacillus salivarius in the cecum of chick. This study emphasized that BSH has anti- Salmonella infection effects in chickens and can be used as a candidate microecological preparation strain.

Multi-Strain Probiotics: Synergy among Isolates Enhances Biological Activities

The use of probiotics for health benefits is becoming popular because of the quest for safer products with protective and therapeutic effects against diseases and infectious agents. The emergence and spread of antimicrobial resistance among pathogens had prompted restrictions over the non-therapeutic use of antibiotics for prophylaxis and growth promotion, especially in animal husbandry. While single-strain probiotics are beneficial to health, multi-strain probiotics might be more helpful because of synergy and additive effects among the individual isolates. This article documents the mechanisms by which multi-strain probiotics exert their effects in managing infectious and non-infectious diseases, inhibiting antibiotic-resistant pathogens and health improvement. The administration of multi-strain probiotics was revealed to effectively alleviate bowel tract conditions, such as irritable bowel syndrome, inhibition of pathogens and modulation of the immune system and gut microbiota. Finally, while most of the current research focuses on comparing the effects of multi-strain and single-strain probiotics, there is a dearth of information on the molecular mechanisms of synergy among multi-strain probiotics isolates. This forms a basis for future research in the development of multi-strain probiotics for enhanced health benefits.

Short-term feeding of probiotics and synbiotics modulates caecal microbiota during Salmonella Typhimurium infection but does not reduce shedding and invasion in chickens

Positive modulation of gut microbiota in laying chickens may offer a strategy for reduction of Salmonella Typhimurium shedding and production of safer poultry products. In the current study, the caecal luminal microbiota of laying chicks was studied using 16S rRNA amplicon sequencing on DNA obtained from the chicks that were offered supplementation with commercial probiotics, synbiotics and/or Salmonella Typhimurium challenge. The load of Salmonella Typhimurium in various organs was quantified. Irrespective of the probiotics and synbiotics supplementation and Salmonella Typhimurium challenge, caecal microbiota was dominated by 22 distinct bacterial genera and 14 families that clustered into Actinobacteria, Proteobacteria and Firmicutes at phylum level. Taken together, probiotics and synbiotics supplementation increased (false discovery rate; FDR < 0.05) the abundance of Ruminococcus, Trabulsiella, Bifidobacterium, Holdemania and Oscillospira, indicating their role in maintaining gut health through lowering luminal pH and digestion of complex polysaccharides. Salmonella Typhimurium challenge decreased the abundance of Trabulsiella, Oscillospira, Holdemania, Coprococcus, Bifidobacterium and Lactobacillus and increased Klebsiella and Escherichia, indicating its role in caecal dysbiosis. Although probiotics and synbiotics supplementation positively modulated the caecal microbiota, they were not effective in significantly (P > 0.05) reducing Salmonella Typhimurium load in caecal tissue and invasion into vital organs such as liver and spleen. The early colonisation of laying chick caeca by probiotics and synbiotics had the potential to positively influence luminal microbiota; however, the microbial abundance and diversity were not sufficient to significantly reduce the shedding of Salmonella Typhimurium in faeces or invasion into internal organs during this study.

Effects of multi-strain probiotic supplementation on intestinal microbiota, tight junctions, and inflammation in young broiler chickens challenged with Salmonella enterica subsp. enterica

Objective

This study assessed the effects of probiotics on cecal microbiota, gene expression of intestinal tight junction proteins, and immune response in the cecal tonsil of broiler chickens challenged with Salmonella enterica subsp. enterica.

Methods

One-day-old broiler chickens (n = 240) were randomly allocated to four treatments: negative control (Cont), multi-strain probiotic-treated group (Pro), Salmonella-infected group (Sal), and multi-strain probiotic-treated and Salmonella-infected group (ProSal). All chickens except those in the Cont and Pro groups were gavaged with 1×10⁸ cfu/mL of S. enterica subsp. enterica 4 days after hatching.

Results

Our results indicated that body weight, weight gain, and feed conversion ratio of birds were significantly reduced (p<0.05) by Salmonella challenge. Chickens challenged with Salmonella decreased cecal microbial diversity. Chickens in the Sal group exhibited abundant Proteobacteria than those in the Cont, Pro, and ProSal groups. Salmonella infection downregulated gene expression of Occludin, zonula occludens-1 (ZO1), and Mucin 2 in the jejunum and Occludin and Claudin in the ileum. Moreover, the Sal group increased gene expression of interferon-γ (IFN-γ), interleukin-6 (IL-6), IL-1β, and lipopolysaccharide-induced tumor necrosis factor-alpha factor (LITAF) and reduced levels of transforming growth factor-β4 and IL-10 compared with the other groups (p<0.05). However, chickens receiving probiotic diets increased Lactobacillaceae abundance and reduced Enterobacteriaceae abundance in the ceca. Moreover, supplementation with probiotics increased the mRNA expression of Occludin, ZO1, and Mucin 2 in the ileum (p<0.05). In addition, probiotic supplementation downregulated the mRNA levels of IFN-γ (p<0.05) and LITAF (p = 0.075) and upregulated IL-10 (p = 0.084) expression in the cecal tonsil.

Conclusion

The administration of multi-strain probiotics modulated intestinal microbiota, gene expression of tight junction proteins, and immunomodulatory activity in broiler chickens.