Feeding a Novel Mannan-Rich Yeast Carbohydrate Product Improves Production Performance and Humoral Immunity of Broiler Chickens

The current study examined the benefits of a novel mannan-rich yeast carbohydrate product (YM) on broiler chicken growth performance and immune response against sheep red blood cells (SRBCs). A total of 144 newly hatched male Cornish cross broiler chicks were randomly assigned to four treatments with 12 cages per treatment and three birds per cage. The treatments were (1) control, basal diet; (2) YCW, basal diet + 1 g/kg yeast cell wall; (3) YM1, basal diet + 0.5 g/kg of a novel yeast mannan-rich product (YM); and (4) YM2, basal diet + 1 g/kg YM. Growth performance was measured at 14, 28, and 35 days of age (d). At 26 and 27 d, nine birds per treatment were immunized intravenously with SRBCs, and antibody responses against SRBCs were analyzed through a hemagglutination assay 7 days post-inoculation. Supplementing YM tended to improve broiler chicken weight gain from 29 to 35 d (p = 0.053). An improvement in the feed conversion ratio (FCR) was observed in the birds fed YM diets during 29-35 d and over the entire experimental period (0-35 d; p < 0.05). Furthermore, birds fed YM2 diets had more robust antibody responses against SRBCs than the control birds (p = 0.033). In conclusion, dietary supplementation of YM improved broiler chicken growth performance and antibody response against SRBCs.

Effects of dietary yeast mannan-rich fraction supplementation on growth performance, intestinal morphology, and lymphoid tissue characteristics in weaned piglets challenged with Escherichia Coli F4

We evaluated the effects of supplementing yeast mannan-reach-fraction on growth performance, jejunal morphology and lymphoid tissue characteristics in weaned piglets challenged with E. Coli F4. A total of 20 crossbred piglets were used. At weaning, piglets were assigned at random to one of four groups: piglets challenged and fed the basal diet supplemented with yeast mannan-rich fraction (C-MRF, n = 5); piglets challenged and fed the basal diet (C-BD, n = 5); piglets not challenged and fed the basal diet supplemented with yeast mannan-rich fraction (NC-MRF, n = 5), and piglets not challenged and fed the basal diet (NC-BD). Each dietary treatment had five replicates. On days 4, 5 and 10, piglets were orally challenged with 108 CFU/mL of E. Coli F4. C-MRF piglets had higher BW (p = 0.002; interactive effect) than C-BD piglets. C-MRF piglets had higher (p = 0.02; interactive effect) ADG in comparison with C-BD piglets. C-MRF piglets had higher (p = 0.04; interactive effect) ADFI than C-BD piglets. The diameter of lymphoid follicles was larger (p = 0.010; interactive effect) in the tonsils of C-MRF piglets than C-BD piglets. Lymphoid cells proliferation was greater in the mesenteric lymphnodes and ileum (p = 0.04 and p = 0.03, respectively) of C-MRF piglets. A reduction (p > 0.05) in E. Coli adherence in the ileum of piglets fed MRF was observed. In conclusion, the results of the present study demonstrate that dietary yeast mannan-rich fraction supplementation was effective in protecting weaned piglets against E. Coli F4 challenge.

A Meta-Analysis of the Effects of Dietary Yeast Mannan-Rich Fraction on Broiler Performance and the Implication for Greenhouse Gas Emissions from Chicken Production

Dietary supplementation of yeast-derived mannan-rich fraction (MRF) could improve the gastrointestinal health and production efficiency of broilers, and, consequently, lower the environmental impacts of chicken production. The objective of this meta-analysis was to quantify the retrospective effects of feeding MRF (Actigen®, Alltech Inc., Nicholasville, KY) on the production performance of broilers. The meta-analysis database included 27 studies and consisted of 66 comparisons of MRF-supplemented diets vs. basal (i.e., negative control) and antibiotic-supplemented (i.e., positive control) diets. A total of 34,596 broilers were involved in the comparisons and the average final age of the birds was 35 days. Additionally, the impact of feeding MRF on the carbon footprint (feed and total emission intensities) of chicken production was evaluated using the meta-analysis results of broiler performance (MRF vs. basal diets) to develop a scenario simulation that was analyzed by a life cycle assessment (LCA) model. A database of all trials (MRF vs. basal and antibiotic diets) indicated that feeding MRF increased (p < 0.01) average daily feed intake (ADFI; +3.7%), final body weight (FBW; +3.5%), and average daily gain (ADG; 4.1%) and improved (p < 0.01) feed conversion ratio (FCR; -1.7%) without affecting (p > 0.05) mortality. A subdatabase of MRF vs. basal diets indicated that dietary MRF increased ADFI (+4.5%), FBW (+4.7%), and ADG (+6.3%) and improved FCR (-2.2%) and mortality (-21.1%). For the subdatabase of MRF vs. antibiotic diets, both treatments exhibited equivalent effects (p > 0.05) on broiler performance parameters, suggesting that MRF could be an effective alternative to in-feed antibiotics. Subgroup analysis revealed that different study factors (year of study, breed/strain, production challenges, and MRF feeding duration) influenced the effect of dietary MRF on broiler performance. Simulated life cycle analysis (LCA) indicated that feeding MRF decreased feed and total emission intensities, on average, by -2.4% and -2.1%, respectively. In conclusion, these results demonstrate that dietary MRF is an effective nutritional solution for improving broiler performance, an effective alternative to in-feed antibiotic growth promoters, and reduces the environmental impact of poultry meat production.

Yeast mannan rich fraction positively influences microbiome uniformity, productivity associated taxa, and lay performance

BACKGROUND

Alternatives to antibiotic as growth promoters in agriculture, such as supplemental prebiotics, are required to maintain healthy and high performing animals without directly contributing to antimicrobial resistance bioburden. While the gut microbiota of broiler hens has been well established and successfully correlated to performance, to our knowledge, a study has yet to be completed on the effect of prebiotic supplementation on correlating the mature laying hen productivity and microbiota. This study focused on establishing the impact of a yeast derived prebiotic, mannan rich fraction (MRF), on the cecal microbiota of late laying hens. This study benefitted from large sample sizes so intra- and intergroup variation effects could be statistically accounted for.

RESULTS

Taxonomic richness was significantly greater at all taxonomic ranks and taxonomic evenness was significantly lower for all taxonomic ranks in MRF-supplemented birds (P < 0.005). Use of principal coordinate analyses and principal component analyses found significant variation between treatment groups. When assessed for compositional uniformity (an indicator of flock health), microbiota in MRF-supplemented birds was more uniform than control birds at the species level. From a food safety and animal welfare perspective, Campylobacter jejuni was significantly lower in abundance in MRF-supplemented birds. In this study, species associated with high weight gain (an anticorrelator of performance in laying hens) were significantly lower in abundance in laying hens while health-correlated butyrate and propionate producing species were significantly greater in abundance in MRF-supplemented birds.

CONCLUSIONS

The use of prebiotics may be a key factor in controlling the microbiota balance limiting agri-food chain pathogen persistence and in promoting uniformity. In previous studies, increased α- and β-diversity indices were determinants of pathogen mitigation and performance. MRF-supplemented birds in this study established greater α- and β-diversity indices in post-peak laying hens, greater compositional uniformity across samples, a lower pathogenic bioburden and a greater abundance of correlators of performance.

The Role of Dietary Supplementation of Yeast Cell Walls in Response to a Campylobacter jejuni Inoculation in Broiler Chickens

Controlling Campylobacter jejuni during broiler production is a topic of interest from a public health standpoint, as colonized birds can contaminate poultry products during processing and sicken humans if not properly cooked or handled before consumption. The aim of this study was to evaluate dietary yeast cell wall (YCW) as a potential alternative to antibiotic growth promoters with or without a C. jejuni challenge. A total of 2240 day-old Ross 708 males were randomly assigned within 8 experimental groups with a 4 × 2 factorial design, with 4 diets (negative control [CTL-], positive control [CTL+, bacitracin, 50 g/ ton], YCW constant dose [400 g/ton], and YCW step-down dose [SD, 800, 400, and 200 g/ton in the starter, grower, and finisher periods, respectively]) and with or without a Day-16 C. jejuni oral gavage challenge at a 103-colony-forming-units (CFU)/ml dose. Body weights and feed consumption were measured on Days 0, 14, 28, and 41 to determine broiler performance. Ileum tissue samples were collected from 24 birds per treatment on Days 17 and 24 (1 and 8 days postinoculation [PI]) for relative gene expression (RGE) analysis. Cecal content samples were collected from 24 birds per treatment on Days 24, 34, and 42 for C. jejuni enumeration and prevalence calculation. A total of 80 birds per treatment were processed to determine carcass yield on Day 44, and on Day 45, 16 carcass rinsates per treatment were collected for C. jejuni enumeration and prevalence calculation. The interaction between diet and inoculation did not influence growth performance (P > 0.05). However, a diet effect was observed in the starter period where birds fed SD diet had a lower feed conversion ratio than birds fed CTL- diet (P = 0.0165). Additionally, the treatment of birds inoculated with C. jejuni fed with SD had a trend to a lower feed conversion ratio during the grower period (P = 0.0550). The RGE of interleukin 1β and interleukin 10 was similar in all treatments 1 and 8 days PI. The RGE of avian beta defensin 10 was similar in all treatments on Day 1 PI, but different on Day 8 PI (P = 0.0476). All birds inoculated with C. jejuni had similar CFU per milliliter counts in the cecal contents at Days 24, 34, and 42 (P > 0.05), and all birds inoculated with phosphate-buffered saline were negative for C. jejuni after prevalence testing. After processing 1) carcass yield was similar in all treatments (P > 0.05); 2) C. jejuni-inoculated birds fed CTL- had lower CFU per milliliter counts than birds provided CTL+ and constant-dose diets (P = 0.0383); and 3) all birds inoculated with PBS were negative for Campylobacter. Overall, under the conditions of this study, the addition of YCW during a C. jejuni challenge did not have an impact on growth performance, innate immune response, cecal colonization, carcass yield, or carcass colonization after processing.

Advances in enteropathogen control throughout the meat chicken production chain

Enteropathogens, namely Salmonella and Campylobacter, are a concern in global public health and have been attributed in numerous risk assessments to a poultry source. During the last decade, a large body of research addressing this problem has been published. The literature reviewed contains review articles on certain aspects of poultry production chain; however, in the past decade there has not been a review on the entire chain-farm to fork-of poultry production. For this review, a pool of 514 articles were selected for relevance via a systematic screening process (from >7500 original search articles). These studies identified a diversity of management and intervention strategies for the elimination or reduction of enteropathogens in poultry production. Many studies were laboratory or limited field trials with implementation in true commercial operations being problematic. Entities considering using commercial antienteropathogen products and interventions are advised to perform an internal validation and fit-for-purpose trial as Salmonella and Campylobacter serovars and biovars may have regional diversity. Future research should focus on nonchemical application within the processing plant and how a combination of synergisticinterventions through the production chain may contribute to reducing the overall carcass burden of enteropathogens, coupled with increased consumer education on safe handling and cooking of poultry.

Campylobacter jejuni: targeting host cells, adhesion, invasion, and survival

Campylobacter jejuni, causing strong enteritis, is an unusual bacterium with numerous peculiarities. Chemotactically controlled motility in viscous milieu allows targeted navigation to intestinal mucus and colonization. By phase variation, quorum sensing, extensive O-and N-glycosylation and use of the flagellum as type-3-secretion system C. jejuni adapts effectively to environmental conditions. C. jejuni utilizes proteases to open cell-cell junctions and subsequently transmigrates paracellularly. Fibronectin at the basolateral side of polarized epithelial cells serves as binding site for adhesins CadF and FlpA, leading to intracellular signaling, which again triggers membrane ruffling and reduced host cell migration by focal adhesion. Cell contacts of C. jejuni results in its secretion of invasion antigens, which induce membrane ruffling by paxillin-independent pathway. In addition to fibronectin-binding proteins, other adhesins with other target structures and lectins and their corresponding sugar structures are involved in host-pathogen interaction. Invasion into the intestinal epithelial cell depends on host cell structures. Fibronectin, clathrin, and dynein influence cytoskeletal restructuring, endocytosis, and vesicular transport, through different mechanisms. C. jejuni can persist over a 72-h period in the cell. Campylobacter-containing vacuoles, avoid fusion with lysosomes and enter the perinuclear space via dynein, inducing signaling pathways. Secretion of cytolethal distending toxin directs the cell into programmed cell death, including the pyroptotic release of proinflammatory substances from the destroyed cell compartments. The immune system reacts with an inflammatory cascade by participation of numerous immune cells. The development of autoantibodies, directed not only against lipooligosaccharides, but also against endogenous gangliosides, triggers autoimmune diseases. Lesions of the epithelium result in loss of electrolytes, water, and blood, leading to diarrhea, which flushes out mucus containing C. jejuni. Together with the response of the immune system, this limits infection time. Based on the structural interactions between host cell and bacterium, the numerous virulence mechanisms, signaling, and effects that characterize the infection process of C. jejuni, a wide variety of targets for attenuation of the pathogen can be characterized. The review summarizes strategies of C. jejuni for host-pathogen interaction and should stimulate innovative research towards improved definition of targets for future drug development. KEY POINTS: • Bacterial adhesion of Campylobacter to host cells and invasion into host cells are strictly coordinated processes, which can serve as targets to prevent infection. • Reaction and signalling of host cell depend on the cell type. • Campylobacter virulence factors can be used as targets for development of antivirulence drug compounds.

Effects of dietary yeast cell wall supplementation on growth performance, intestinal Campylobacter jejuni colonization, innate immune response, villus height, crypt depth, and slaughter characteristics of broiler chickens inoculated with Campylobacter jejuni at d 21

A study was conducted to assess the effects of a dietary yeast cell wall (YCW) with and without a Campylobacter jejuni (CJ) challenge. A total of 2,240-day-old Ross 708 males were randomly assigned within 8 treatments with a 4 × 2 factorial design, with 4 diets (negative control, positive control, YCW constant dose (400 g/ton), and YCW step-down dose (800/400/200 g/ton in the starter/grower/finisher diets, respectively) and with and without d 21 CJ oral gavage challenge at 5.2 × 10⁷ CFU/mL. At d 0, 14, 28, and 41 body weights and feed consumption were measured to determine performance. At d 14, 28, and 42, 8 jejunal and ileal histology samples per treatment were collected for villi morphology measurements. At d 22 and 28 (1- and 7-days postinoculation), 24 ileal tissue samples per treatment were collected for relative gene expression analysis. At d 42, 24 cecal content samples per treatment were collected for CJ enumeration. Finally, on d 44, 96 birds per treatment were processed to determine carcass yield and 16 carcass rinses per treatment were collected to determine CJ prevalence after processing. Diet or inoculation did not impact broiler performance (P > 0.05). Limited differences were observed in intestinal morphology, and villus height and crypt depth were different only in the ileum at d 42 (P = 0.0280 and P = 0.0162, respectively). At d 1 postinoculation, differences between treatments inoculated with CJ and PBS were observed in the expression of avian beta defensin 10 (AvBD10), interleukin 1ß (IL-1ß), and interleukin 10 (IL-10) (P < 0.05). At d 7 postinoculation, expression of AvBD10, IL-1ß, and IL-10 was similar among all treatments (P > 0.05). At d 42, all birds, regardless the inoculation, had similar levels of CJ recovered from cecal contents (P > 0.05). After processing, carcass yield and CJ prevalence postchilling was similar in all treatments (P > 0.05). Overall, under the conditions of this study, the addition of YCW during a CJ challenge did not have an impact in growth performance, innate immune response, cecal colonization, carcass yield, or CJ prevalence after processing.

Mannan based prebiotics modulate growth rate and energy phenotype of tetracycline resistant E. coli

Unsustainable antimicrobial use in industrial agriculture has contributed to the rise in antimicrobial resistance and there is an urgent need to find alternative and more sustainable strategies to traditional antimicrobials. Prebiotics, such as mannan-rich fraction (MRF), a cell wall product from Saccharomyces cerevisiae, have demonstrated an ability to alter the growth of antibiotic susceptible and resistant Escherichia coli and improve the efficacy of antibiotics through modulation of cellular activity. In this study the impact of mannan based prebiotics on growth and respiration of E. coli was assessed by observing microbial growth, oxygen consumption rate and extracellular acidification rate in the presence and absence of tetracycline. The findings further demonstrate the capabilities of MRF with respect to improving microbial antibiotic sensitivity, particularly in resistant strains. This potentially enables a more efficient control of resistant pathogens with food safety implications and promotion of more sustainable use of antibiotics in animal production systems.

Yeast Mannan-Rich Fraction Modulates Endogenous Reactive Oxygen Species Generation and Antibiotic Sensitivity in Resistant E. coli

Mannan-rich fraction (MRF) isolated from Saccharomyces cerevisiae has been studied for its beneficial impact on animal intestinal health. Herein, we examined how MRF affected the formation of reactive oxygen species (ROS), impacting antibiotic susceptibility in resistant Escherichia coli through the modulation of bacterial metabolism. The role of MRF in effecting proteomic change was examined using a proteomics-based approach. The results showed that MRF, when combined with bactericidal antibiotic treatment, increased ROS production in resistant E. coli by 59.29 ± 4.03% compared to the control (p ≤ 0.05). We further examined the effect of MRF alone and in combination with antibiotic treatment on E. coli growth and explored how MRF potentiates bacterial susceptibility to antibiotics via proteomic changes in key metabolic pathways. Herein we demonstrated that MRF supplementation in the growth media of ampicillin-resistant E. coli had a significant impact on the normal translational control of the central metabolic pathways, including those involved in the glycolysis-TCA cycle (p ≤ 0.05).

Effect of Mannan-rich fraction supplementation on commercial broiler intestinum tenue and cecum microbiota

BACKGROUND

The broiler gastrointestinal microbiome is a potent flock performance modulator yet may also serve as a reservoir for pathogen entry into the food chain. The goal of this project was to characterise the effect of mannan rich fraction (MRF) supplementation on microbiome diversity and composition of the intestinum tenue and cecum of commercial broilers. This study also aimed to address some of the intrinsic biases that exist in microbiome studies which arise due to the extensive disparity in 16S rRNA gene copy numbers between bacterial species and due to large intersample variation.

RESULTS

We observed a divergent yet rich microbiome structure between different anatomical sites and observed the explicit effect MRF supplementation had on community structure, diversity, and pathogen modulation. Birds supplemented with MRF displayed significantly higher species richness in the cecum and significantly different bacterial community composition in each gastrointestinal (GI) tract section. Supplemented birds had lower levels of the zoonotic pathogens Escherichia coli and Clostridioides difficile across all three intestinum tenue sites highlighting the potential of MRF supplementation in maintaining food chain integrity. Higher levels of probiotic genera (eg. Lactobacillus and Blautia) were also noted in the MRF supplemented birds. Following MRF supplementation, the cecum displayed higher relative abundances of both short chain fatty acid (SFCA) synthesising bacteria and SCFA concentrations.

CONCLUSIONS

Mannan rich fraction addition has been observed to reduce the bioburden of pathogens in broilers and to promote greater intestinal tract microbial biodiversity. This study is the first, to our knowledge, to investigate the effect of mannan-rich fraction supplementation on the microbiome associated with different GI tract anatomical geographies. In addition to this novelty, this study also exploited machine learning and biostatistical techniques to correct the intrinsic biases associated with microbiome community studies to enable a more robust understanding of community structure.

Quantitative Proteomic Analysis Reveals Yeast Cell Wall Products Influence the Serum Proteome Composition of Broiler Chickens

With an ever-growing market and continual financial pressures associated with the prohibition of antibiotic growth promoters, the poultry industry has had to rapidly develop non-antibiotic alternatives to increase production yields. A possible alternative is yeast and its derivatives, such as the yeast cell wall (YCW), which have been proposed to confer selected beneficial effects on the host animal. Here, the effect of YCW supplementation on the broiler chicken was investigated using a quantitative proteomic strategy, whereby serum was obtained from three groups of broilers fed with distinct YCW-based Gut Health Products (GHP) or a control basal diet. Development of a novel reagent enabled application of ProteoMiner™ technology for sample preparation and subsequent comparative quantitative proteomic analysis revealed proteins which showed a significant change in abundance (n = 167 individual proteins; p < 0.05); as well as proteins which were uniquely identified (n = 52) in, or absent (n = 37) from, GHP-fed treatment groups versus controls. An average of 7.1% of proteins showed changes in abundance with GHP supplementation. Several effects of these GHPs including immunostimulation (via elevated complement protein detection), potential alterations in the oxidative status of the animal (e.g., glutathione peroxidase and catalase), stimulation of metabolic processes (e.g., differential abundance of glyceraldehyde-3-phosphate dehydrogenase), as well as evidence of a possible hepatoprotective effect (attenuated levels of serum α-glutathione s-transferase) by one GHP feed supplement, were observed. It is proposed that specific protein detection may be indicative of GHP efficacy to stimulate broiler immune status, i.e., may be biomarkers of GHP efficacy. In summary, this work has developed a novel technology for the preparation of high dynamic range proteomic samples for LC-MS/MS analysis, is part of the growing area of livestock proteomics and, importantly, provides evidential support for beneficial effects that GHP supplementation has on the broiler chicken.

Performance and environmental impact of egg production in response to dietary supplementation of mannan oligosaccharide in laying hens: a meta-analysis

A meta-analysis was conducted to examine the effect of supplementing mannan oligosaccharide (MOS; Bio-Mos, Alltech Inc., Nicholasville, KY) in the diets of laying hens on the performance and environmental impact of egg production. Data on production performance (feed intake, hen-day production [HDP], feed conversion ratio [FCR], and mortality) and egg quality attributes (egg weight, egg mass, and eggshell thickness) were extracted from 18 studies to build a database of comparisons between nonsupplemented diets (control) and diets supplemented with MOS. A total of 4,664 laying hens were involved in the comparisons and the average MOS dosage and age of hens were 0.97 kg/ton and 44 wk, respectively. The dataset was analyzed using the random-effects model to estimate the effect size of MOS supplementation on production performance and egg quality attributes. The impact of feeding MOS on the carbon footprint (feed and total emission intensities) of egg production was evaluated by using the meta-analysis results of production performance to develop a scenario simulation that was analyzed by a life cycle assessment (LCA) model. Overall pooled effect size (raw mean difference) indicated that MOS supplementation did not affect feed intake. In contrast, HDP increased by +1.76% and, FCR and mortality reduced by -26.64 g feed/kg egg and -2.39%, respectively. Dietary MOS did not influence egg weight while egg mass increased (P < 0.01) by +0.95 g/day/hen and eggshell thickness tended to increase (P = 0.07) by +0.05 mm. Subgroup analysis indicated that dietary MOS exhibited consistent improvement on HDP and FCR under several study factors (age of hens, number of hens, production challenges, MOS dosage, and study duration). Additionally, the simulated LCA revealed that supplementing MOS decreased feed and total emission intensities of egg production by -1.3 and -1.5%, respectively. Overall, dietary supplementation of MOS at 1.0 kg/ton improved the production performance of laying hens and reduced the carbon footprint and, therefore, can enhance the sustainability credentials of egg production.

Effect of yeast cell wall supplementation on intestinal integrity, digestive enzyme activity and immune traits of broilers

1. The protective layer formed by intestinal epithelial cells acts as a barrier preventing the adhesion of pathogenic bacteria, aids digestion and passage of nutrients and reduces damage caused from toxins on the gastrointestinal tract. This study was conducted to investigate the effects of a yeast cell wall-based product (YCW), on broiler intestinal integrity, digestive enzyme capacity and immune function.2. A 35-d trial involving 246, one-d-of-hatch male broiler chickens was carried out at a trial facility at Agri-Food Biosciences Institute (AFBI, Belfast, UK). Birds were randomly allocated into 6 pens at day of hatch (41 birds/pen; 123 birds/group). Pens were divided into two groups: (1) basal diet and (2) basal diet that incorporated YCW at the manufacturers' recommended inclusion levels (Alltech Inc., Lexington, Kentucky, USA).3. In this study, YCW supplementation affected broiler intestinal morphology resulting in greater crypt depth, villus height and surface area, goblet cell density and mucus layer thickness and lower muscularis mucosae thickness. The digestive enzymes, maltase, sucrase and alkaline phosphatase, were significantly higher in the YCW supplemented group compared to the control. The expression levels of pro-inflammatory cytokines, IL-1β, IL-12 and IL-18, were significantly lower as was necroptotic cell death in YCW supplemented birds.4. In conclusion, under the conditions of this study, YCW supplementation positively affected intestinal health parameters in broilers following 35-d supplementation.

Assessment of the Effectiveness of Pre-harvest Meat Safety Interventions to Control Foodborne Pathogens in Broilers: a Systematic Review

Purpose of Review

Ensuring broilers’ meat safety is a priority to policy makers, producers, and consumers. This systematic review aims to update the recent knowledge on pre-harvest interventions to control main foodborne pathogens in broilers and to assess their effectiveness.

Recent Findings

A total of 815 studies were retrieved from PubMed® and Web of Science for 13 pathogens. In total, 51 studies regarding Campylobacter spp., Salmonella spp., VTEC, ESBL-AmpC Escherichia coli, and Clostridium perfringens were included in this review.

Summary

Research mostly focused on Salmonella spp. and Campylobacter spp. Biosecurity and management interventions had mixed outcomes, while the effectiveness of feed additives, though intensively researched, remains controversial. Research on other pathogens (i.e. ESBL-AmpC E. coli/Salmonella, and Toxoplasma gondii) was scarce, with publications focusing on epidemiology and/or on source-attribution studies. This is also true regarding research on Listeria monocytogenes, Bacillus cereus, Clostridium botulinum, Clostridium perfringens, and Staphylococcus aureus as these are frequently controlled by post-harvest interventions. Overall, studies on recent developments of novel pathogen-specific immunisation strategies are lacking.

The effect of natural antimicrobials on the Campylobacter coli T6SS+/- during in vitro infection assays and on their ability to adhere to chicken skin and carcasses

Reducing the Campylobacter load on poultry carcasses represents a major tasks for the industry as its ability to reduce their presence is of major interest aiming to increase consumer safety. This study investigated the ability of a mixture of natural antimicrobials (A3001) to reduce the adherence of the T6SS^+/-C. coli isolates (NC1^hcp-, NC2 ^hcp- and NC3 ^hcp+) to chicken neck skin and whole carcasses. Overall, the antimicrobial mixture induced a significant reduction in the capability of our C. coli isolates to colonise the chicken skin (p < 0.05) and carcasses (p < 0.0001) but with a greater effect (≈3 log reduction) on the NC3 isolate. Using the HCT-8 in vitro infection model we also show that at a concentration of 0.5% A3001, the impact on the NC3 isolate is accompanied by the downregulation of the hcp gene (p = 0.0001), and indicator of the T6SS presence. The results described herein also indicated that these isolates are highly resistant to H₂O₂, up to 20 mM, suggesting a high resilience to environmental stresses. In summary our study shows that natural antimicrobials can reduce the ability of T6SS positive chicken C. coli isolates to adhere to chicken skin or to the whole carcass and to infect epithelial cells in vitro and could be considered a potential intervention at processor level.

Effects of a mannan-rich yeast cell wall-derived preparation on cecal concentrations and tissue prevalence of Salmonella Enteritidis in layer chickens

Salmonella Enteritidis (SE) has been the most common Salmonella serotype associated with foodborne infections in the last several years. Dietary applications of yeast-based preparations in feed have shown to reduce Salmonella colonization in chickens augmenting SE control strategies. This study was conducted to evaluate the effects of a mannan-rich yeast cell wall-derived preparation (Actigen^®) administered in feed at a rate of 400 g/ton on SE colonization in the cecum and internal organs of commercial layer chickens. Sixteen week-old layer pullets were orally challenged with a selected nalidixic acid resistant SE strain at a dose of 1.7×10^9 colony forming units (CFU) per bird. SE colonization was assessed by evaluating isolation rates from ovary and pooled liver/spleen samples as well as enumeration of SE in cecal pouches one week post-challenge. Recovery rates of SE from the ovaries of directly challenged birds receiving Actigen^® were significantly lower (P <0.02) than those in directly challenged birds fed an unsupplemented control diet. Recovery rates of SE from pooled liver/spleen samples were not significantly different between Actigen^®-treated pullets and controls (P = 0.22). Using direct plate count methods, cecal SE concentrations were 1 log₁₀ lower (P <0.001) in challenged pullets in the Actigen^®-supplemented group than in the challenged controls. The SE concentration distributions in the ceca were similar in groups testing positive and groups testing negative for SE in the ovaries and liver/spleens tissues. As a result, SE concentrations in the ceca could not be directly related to the occurrence or prevalence of SE in these tissues. In conclusion, Actigen^® supplementation appears to decrease the prevalence of SE in ovarian tissue and concentrations of SE in cecal contents and may be useful as a tool for reducing the risk of eggshell contamination and transovarian transmission of SE in eggs.

The effect of a selected yeast fraction on the prevention of pullorum disease and fowl typhoid in commercial breeder chickens

A selected yeast fraction (SYF) was tested for the purpose of preventing pullorum disease and fowl typhoid in breeder chickens. In a challenge-protection experiment, commercial Three-Yellow breeder chicks were initially divided into groups A, B (challenged, treated), C (challenged, untreated), and D (unchallenged, untreated). The group A diet was supplemented with SYF and group B was supplemented with Acidipure via drinking water. At 7 D, birds of groups A, B, and C were divided into 2 equal subgroups (A1-A2, B1-B2, and C1-C2). Subgroups A1, B1, and C1 were challenged with Salmonella pullorum (SP), while subgroups A2, B2, and C2 were challenged with Salmonella gallinarum (SG). Clinical signs and mortality were recorded daily. At intervals, antibodies against SP and SG were detected by a plate agglutinate test (PAT). At 42 D, all birds were weighed and necropsied, lesions were recorded and challenge pathogens were isolated. Results showed that SP and SG isolation positive rates of groups A1-A2 were significantly lower (P < 0.05) than those of B1-B2 and C1-C2, respectively. The average body weight (BW) of groups A1-A2 was significantly higher (P < 0.05) than that of B1-B2 and C1-C2, respectively. In the field trial, chicks were randomly divided into 3 groups. Group 1 birds were fed a diet supplemented with SYF, group 2 diet was supplemented with Acidipure via drinking water, and group 3 was fed the same but un-supplemented diet as the control group. Antibodies against SP and SG were detected by PAT at 120 D. The antibodies positive rate of group 1 was significantly lower (P < 0.05) than those of groups 2 and 3, while no significant difference (P > 0.05) was found between groups 2 and 3. The results demonstrated that SYF supplementation could significantly decrease SP and SG infection rates, improve the BW of birds challenged with SP and SG, and was more effective than Acidipure via drinking water.