Dietary inclusion of a Saccharomyces cerevisiae metabolite improved reproductive performance but did not affect intestinal permeability in two chicken meat breeder lines

Gastrointestinal dysbiosis is a disturbance in mucosal homeostasis, producing low-grade chronic intestinal inflammation and impaired intestinal barrier function. It is induced by several factors, including nutrition and stress, which are both significant factors when considering current broiler breeder practices. A great grandparent (GGP) chicken meat line was identified displaying clinical signs characteristic of potential dysbiosis, including wet droppings and litter, in addition to reduced reproductive performance when compared to a consistently high performing line. This study aimed to determine whether the reduced reproductive performance observed in these hens was a result of dysbiosis and whether dietary supplementation with a Saccharomyces cerevisiae (SC) fermentation product would alleviate clinical signs. Dietary inclusion of SC did not influence intestinal permeability, WBC differentials, or corticosterone concentration in either the wet litter (WL) or high-performing (HP) breeder lines. Compared to hens from the HP line, WL line hens had a significant increase in intestinal permeability at 26 wk (onset of lay). WL hen heterophil counts were increased markedly at week 26 before declining. At weeks 26, 32, and 37 there were also significant increases in monocytes. Higher plasma corticosterone was also observed in WL hens at 37 wk. No significant differences in heterophil to lymphocyte (H:L) ratios or feather corticosterone were observed between lines. Dietary inclusion of SC supplementation to breeder diets had some benefit in regards to reducing hen mortality, improving egg production and hatchability but only in the WL line. Results from this study did not indicate that hens from the wet litter line were experiencing gut dysbiosis. Chronic intestinal inflammation may be a possible reason for the increase in intestinal permeability. These results do indicate that both breeder lines may be exhibiting physiological stress. Future investigation into the physiology and behavior around point of lay is required to find novel strategies to alleviate this stress and in turn, potentially improve welfare and production outcomes.

Comparison of yeast-derived commercial feed additives on Salmonella Enteritidis survival and microbiota populations in rooster cecal in vitro incubations

Yeast-derived products have become more of an interest in the poultry industry as of late because of their use in modulating the gastrointestinal tract (GIT) microbiome to both improve production parameters and prevent infection. This study aimed to evaluate the effects of various yeast-derived products on Salmonella enterica inoculation in un in vitro rooster cecal incubations and associated effects on the cecal microbiome. Cecal contents were obtained from 53-wk old White Leghorn H & N Nick Chick roosters (n = 3) fed a wheat-based, commercial-type basal diet. Cecal contents were diluted 1:3000 in anaerobic dilution solution (ADS) in an anaerobic chamber, with 20 mL aliquoted to each serum bottle. There were three controls (n = 3): basal diet only, diluted cecal contents only, and basal diet and diluted cecal contents; and five treatments containing the basal diet and diluted cecal contents (n = 3): Citristim® (ADM), ImmunoWall® (ICC), Maxi-Gen Plus® (CBS Bio Platforms), Hilyses® (ICC), and Original XPC® (Diamond V). All treatments were applied at a rate of 2.5 kg/tonne or less. All groups were inoculated with a nalidixic acid-resistant strain of Salmonella Enteritidis at 10^7 CFU/mL and incubated at 37 deg C. Samples were collected at 0, 24, and 48 h for S. Enteritidis enumeration and 16S rDNA microbial sequencing. Salmonella data were log-transformed and analyzed in a two-way ANOVA with means separated using Tukey's HSD (P≤0.05). Genomic DNA was extracted, and resulting libraries were prepared and sequenced using an Illumina MiSeq. Sequencing data were analyzed in QIIME2 (2021.4) with diversity metrics (alpha and beta), and an analysis of the composition of microbiomes (ANCOM) was performed. Main effects were considered significant at P≤0.05, with pairwise differences considered significant at Q≤0.05. There was an interaction of treatment and time on the enumeration of Salmonella where treatments of Citristim, Immunowall, Hilyses, and XPC reduced Salmonella by 1 log CFU/mL compared to the controls. At 48 h, each yeast product treatment reduced Salmonella by 3 log CFU/mL compared to the controls. There was no main effect of treatment on the alpha diversity metrics, richness, or evenness (P > 0.05). Treatment affected the beta diversity, abundance, and phylogenetic differences, but there were no pairwise differences (P>0.05, Q>0.05). Using ANCOM at the genus level, the taxa Synergistes, Alloprevotella, Sutterella, and Megasphaera abundance were significantly different (W = 154,147,145,140, respectively). These results demonstrate the potential of these yeast-derived products to reduce foodborne pathogens, such as Salmonella Enteriditis, in vitro, without negatively disrupting the cecal microbiome.

Research Note: Preliminary assessment of the impact of dietary yeast products on egg production and cecal microbial profiles of laying hens

The objective of the current study was to conduct an initial comparison of commercial yeast products in layer hen diets on egg production parameters and the corresponding impact on the cecal microbiota. A short-term feeding study was conducted with 35 laying hens receiving either a control, or 1 of 4 different yeast fermentation products, Immunowall, Hilyses (both from ICC, São Paulo, Brazil), Citristim (ADM, Decatur, IL), and Maxi-Gen Plus (CBS Bio Platforms, Calgary, Canada) with 7 hens per treatment from 40 to 46 wk of age. At the end of the trial, hens were euthanized, the ceca removed and prepared for denatured gradient gel electrophoresis (DGGE) microbial compositional analyses. Although initial shell weight and shell thickness were similar among the treatment groups, hens fed Hilyses had lower shell weight and thickness at the end of the experiment. The most predominant DGGE bands with the strongest intensity were identified as Lactobacillus species and excised double bands were identified as Bacillus, Clostridium, or Lachnospiraceae. In this short-term feeding trial, the commercial yeast products tested had little effect on egg production and shell quality, and only moderately impacted the composition of mature layer hen cecal microbiota.

Effect of a Saccharomyces cerevisiae Postbiotic Feed Additive on Salmonella Enteritidis Colonization of Cecal and Ovarian Tissues in Directly Challenged and Horizontally Exposed Layer Pullets

Determining the efficacy of feed-additive technologies utilized as pre-harvest food-safety interventions against Salmonella enterica may be influenced by factors including, but not limited to, mechanism of action, experimental design variables, Salmonella serovar(s), exposure dose, route, or duration in both controlled research and real-world field observations. The purpose of this study was to evaluate the dietary inclusion of a Saccharomyces cerevisiae fermentation-derived postbiotic (SCFP) additive (Diamond V, Original XPC®) on the colonization of cecal and ovarian tissues of commercial pullets directly and indirectly exposed to Salmonella Enteritidis (SE). Four hundred and eighty commercial, day-of-age W-36 chicks were randomly allotted to 60 cages per treatment in two identical BSL-2 isolation rooms (Iowa State University) with four birds per cage and fed control (CON) or treatment (TRT) diets for the duration of study. At 16 weeks, two birds per cage were directly challenged via oral gavage with 1.1 × 109 CFU of a nalidixic-acid-resistant SE strain. The remaining two birds in each cage were thus horizontally exposed to the SE challenge. At 3, 7, and 14 days post-challenge (DPC), 20 cages per group were harvested and sampled for SE prevalence and load. No significant differences were observed between groups for SE prevalence in the ceca or ovary tissues of directly challenged birds. For the indirectly exposed cohort, SE cecal prevalence at 7 DPC was significantly lower for TRT (50.0%) vs. CON (72.5%) (p = 0.037) and, likewise, demonstrated significantly lower mean SE cecal load (1.69 Log10) vs. CON (2.83 Log10) (p = 0.005). At 14 DPC, no significant differences were detected but ~10% fewer birds remained positive in the TRT group vs. CON (p > 0.05). These findings suggest that diets supplemented with SCFP postbiotic may be a useful tool for mitigating SE colonization in horizontally exposed pullets and may support pre-harvest food-safety strategies.

Development of an In Vivo Extended-Spectrum Cephalosporin-Resistant Escherichia coli Model in Post-Weaned Pigs and Its Use in Assessment of Dietary Interventions

Current interventions targeting antimicrobial resistance (AMR), a major impact on commercial pork production, focus on reducing the emergence of AMR by minimising antimicrobial usage through antimicrobial stewardship and a range of alternative control methods. Although these strategies require continued advancement, strategies that directly aim to reduce or eliminate existing antimicrobial resistant bacteria, specifically bacteria resistant to critically important antimicrobials (CIAs), need to be investigated and established. This study established an in vivo model for examining the effects of postbiotics, in the form of Lactobacillus acidophilus fermentation products (LFP) and Saccharomyces cerevisiae fermentation products (SFP), on the shedding of extended-spectrum cephalosporin (ESC)-resistant E. coli. The model was successful in demonstrating the presence of ESC-resistant E. coli as evidenced by its detection in 62 of 64 pigs. There was a strong trend (p = 0.065) for the SFP postbiotics to reduce the shedding of ESC-resistant E. coli, indicating positive impacts of this additive on reducing the carriage of bacteria resistant to CIAs. Overall, this in vivo model enables future evaluation of strategies targeting ESC-resistant E. coli while increasing our knowledge on the carriage of ESC-resistant E. coli in pigs.

Effects of a postbiotic, with and without a saponin-based product, on turkey performance

Modern poultry production relies on an ability to prevent and mitigate challenges to bird health, while maintaining a productive bird. A number of different classes of biologics-based feed additives exist, and many have been tested individually for their impacts on poultry health and performance. Fewer studies have examined the combinations of different classes of products. In this study, we examined the use of a well-established postbiotic feed additive (Original XPC, Diamond V) on turkey performance, with and without the addition of a proprietary saponin-based feed additive. This was accomplished in an 18-wk pen trial utilizing 22 pen replicates per treatment across 3 treatments (control, postbiotic, and postbiotic plus saponin). Significant differences in body weight were identified at wk 12 and 15 of age, with the postbiotic plus saponin treatment group resulting in heavier birds at both timepoints. Significant differences in feed conversion ratio were observed from 0 to 18 wk of age, with the postbiotic alone having improved FCR compared with the control group. No significant differences were observed for livability or feed intake. This study demonstrates that a combination of a postbiotic plus saponin may exert additive effects on the growth of the turkey.

Yeast-Derived Products: The Role of Hydrolyzed Yeast and Yeast Culture in Poultry Nutrition—A Review

Simple Summary

Yeast and yeast-derived products are largely employed in animal nutrition to support animals’ health and to improve their performance. Thanks to their components, including mannans, β-glucans, nucleotides, vitamins, and other compounds, yeasts have numerous beneficial effects. Among yeast-derived products, hydrolyzed yeasts and yeast cultures have received less attention, but, although the results are somewhat conflicting, in most of the cases, the available literature shows improved performance and health in poultry. Thus, the aim of this review is to provide an overview of hydrolyzed-yeast and yeast-culture employment in poultry nutrition, exploring their effects on the production performance, immune response, oxidative status, gut health, and nutrient digestibility. A brief description of the main yeast bioactive compounds is also provided.

Abstract

Yeasts are single-cell eukaryotic microorganisms that are largely employed in animal nutrition for their beneficial effects, which are owed to their cellular components and bioactive compounds, among which are mannans, β-glucans, nucleotides, mannan oligosaccharides, and others. While the employment of live yeast cells as probiotics in poultry nutrition has already been largely reviewed, less information is available on yeast-derived products, such as hydrolyzed yeast (HY) and yeast culture (YC). The aim of this review is to provide the reader with an overview of the available body of literature on HY and YC and their effects on poultry. A brief description of the main components of the yeast cell that is considered to be responsible for the beneficial effects on animals’ health is also provided. HY and YC appear to have beneficial effects on the poultry growth and production performance, as well as on the immune response and gut health. Most of the beneficial effects of HY and YC have been attributed to their ability to modulate the gut microbiota, stimulating the growth of beneficial bacteria and reducing pathogen colonization. However, there are still many areas to be investigated to better understand and disentangle the effects and mechanisms of action of HY and YC.

Dietary Inclusion of a Saccharomyces cerevisiae-Derived Postbiotic Is Associated with Lower Salmonella enterica Burden in Broiler Chickens on a Commercial Farm in Honduras

Postbiotic feed additives may aid foodborne pathogen reduction during poultry rearing. The study objective was to evaluate a postbiotic additive in parallel to an industry control diet and the subsequent associated burden of Salmonella enterica on a single, commercial broiler farm in Honduras. Twelve houses were matched and assigned the standard diet (CON) or standard diet plus postbiotic (SCFP). New litter was placed in each house and retained across flock cycles with sampling prior to each chick placement and three consecutive rearing cycles. At ~33–34 days, 25 ceca were collected on-farm from each house, treatment, and cycle. Salmonella prevalence in litter for CON (30.6%) and SCFP (27.8%) were equivalent; however, Salmonella load within positive samples was lower (p = 0.04) for SCFP (3.81 log10 MPN/swab) compared to CON (5.53 log10 MPN/swab). Cecal prevalence of Salmonella was lower (p = 0.0006) in broilers fed SCFP (3.4%) compared to CON (12.2%). Salmonella load within positive ceca were numerically reduced (p = 0.121) by 1.45 log10 MPN/g for SCFP (2.41 log10 MPN/g) over CON (3.86 log10 MPN/g). Estimated burden was lower (p = 0.003) for SCFP flocks (3.80 log10 MPN) compared to CON (7.31 log10 MPN). These data demonstrate the preharvest intervention potential of postbiotics to reduce Salmonella enterica in broiler chickens.

Effect of Feeding a Postbiotic Derived from Saccharomyces cerevisiae Fermentation as a Preharvest Food Safety Hurdle for Reducing Salmonella Enteritidis in the Ceca of Layer Pullets

ABSTRACT

Salmonella Enteritidis is responsible for a significant proportion of foodborne salmonellosis in the United States and continues to be attributable to table eggs despite increased federal oversight. Technologies, including feed additives, continue to be evaluated for preharvest application and their potential food safety benefits. Diamond V Original XPC, a Saccharomyces cerevisiae fermentation-based postbiotic (SCFP), was evaluated for its effectiveness in reducing Salmonella Enteritidis (SE) colonization in young layer pullets. A total of 40 day-old Hy-Line W-36 layer pullets were equally divided and randomly assigned to one of two dietary treatments, with SCFP or without SCFP (PCON), and orally gavaged on day 28 with SE at 106 CFU/mL. Another 20 day-old pullets were fed the same control feed without SCFP and blank inoculated on day 28 with 1 mL of sterile phosphate-buffered saline to serve as a negative control. Qualitative and quantitative analyses of cecal contents for Salmonella were performed for all birds on day 32. The prevalence of SE in the ceca of all directly challenged birds was 100%; however, the SE concentration in birds fed SCFP diet (3.35 log CFU/g) was significantly lower (P < 0.0001) than that of the PCON birds not fed SCFP (4.49 log CFU/g). The proportion of birds with enumerable SE concentrations was lower in SCFP-fed pullets (57.9%) than in the PCON pullets (95.0%). These data suggest that inclusion of SCFP in the diet may aid in the reduction of SE within the ceca of commercial laying hens and could serve as an additional preharvest food safety hurdle.

HIGHLIGHTS

Bacterial meta-analysis of chicken cecal microbiota

Poultry production is an industry that generates 90,000 metric tons of chicken meat worldwide. Thus, optimizing chicken growth and sustainable production is of great importance. A central factor determining not only production parameters, but also stability of the immune system and chicken health, is the diversity and variability of the microbiota present throughout the gastrointestinal tract. To date, several studies have investigated the relationship between bacterial communities and the gut microbiome, with limited data to compare. This study aims to create a bacterial meta-analysis based on studies using amplicon sequencing with Illumina sequencing technologies in order to build a baseline for comparison in future analyses of the cecal bacterial composition in chicken. A systematic literature review was performed (SYRF ID: e84f0468-e418-4eec-9da4-b517f1b4809d. Full project URL: https://app.syrf.org.uk/projects/e84f0468-e418-4eec-9da4-b517f1b4809d/detail). From all the available and analyzed manuscripts only nine contained full raw-sequence data available and the corresponding metadata. A total of 324 samples, comprising three different regions within the 16S rRNA gene, were analyzed. Due to the heterogeneity of the data, each region was analyzed independently and an effort for a joint analysis was performed as well. Taxonomic profiling revealed 11 phyla, with Firmicutes as the most prevalent phylum, followed by Bacteroidetes and Proteobacteria. At genus level, 109 genera were found. Shannon metric for alpha diversity showed that factors like type of chickens (Commercial or experimental) and 16S rRNA gene subregion have negligible effect on diversity. Despite the large number of parameters that were taken into account, the identification of common bacteria showed five genera to be common for all sets in at least 50% of the samples. These genera are highly associated to cellulose degradation and short chain fatty acids synthesis. In general, it was possible to identify some commonalities in the bacterial cecal microbial community despite the extensive variability and factors differing from one study to another.

Growth and humoral immune effects of dietary Original XPC in layer pullets challenged with Mycoplasma gallisepticum

Effects of dietary Original XPC (XPC) in commercial layer pullets challenged with the virulent, low passage R strain of Mycoplasma gallisepticum (R_low MG) were investigated. Hy-Line W-36 pullets sourced from MG-clean breeders were fed a basal diet with or without (CON) XPC (1.25 kg/metric ton) from hatch until 12 wk of age (woa). At 8 and 10 woa, half of the birds in each dietary treatment were challenged with R_low MG. Body weight was recorded at 3, 8, and 12 woa, and ovary, ceca, and bursa weights were recorded at 3 and 12 woa. Blood samples were taken immediately before the initial R_low MG challenge at 8 woa and again at 12 woa to test for IgM and IgG antibody production against MG. All birds were evaluated for MG lesion scores at 12 woa. Regardless of challenge, inclusion of XPC in the diet did not significantly alter BW at 3 or 8 woa or relative organ weights at 3 or 12 woa. However, at 12 woa, BW of XPC-fed birds, regardless of challenge was significantly (P = 0.0038) heavier than CON by 25.7 g. All birds tested negative for MG antibodies before the 8 woa challenge. Respective percentage serum plate agglutination and ELISA positive birds at 12 woa were 0 and 0% (CON, nonchallenged), 1.4 and 0% (XPC, nonchallenged), 100 and 47.2% (CON, challenged), and 100 and 50.0% (XPC, challenged). Diet did not significantly affect ELISA titers, but they were significantly (P < 0.0001) increased due to challenge. Furthermore, lesion scores were significantly higher for R_low MG-challenged birds (P = 0.0012), and dietary treatment with XPC in challenged birds numerically reduced MG lesion scores from 0.278 to 0.194. In conclusion, although dietary XPC did not significantly alter the humoral immune response, antibody titer levels, or severity of MG lesions in layer pullets that were or were not challenged with R_low MG, it led to an increase in their rate of growth through 12 woa.

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

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

A Consistent and Predictable Commercial Broiler Chicken Bacterial Microbiota in Antibiotic-Free Production Displays Strong Correlations with Performance

Defining the baseline bacterial microbiome is critical to understanding its relationship with health and disease. In broiler chickens, the core microbiome and its possible relationships with health and disease have been difficult to define, due to high variability between birds and flocks. Presented here are data from a large, comprehensive microbiota-based study in commercial broilers. The primary goals of this study included understanding what constitutes the core bacterial microbiota in the broiler gastrointestinal, respiratory, and barn environments; how these core players change across age, geography, and time; and which bacterial taxa correlate with enhanced bird performance in antibiotic-free flocks. Using 2,309 samples from 37 different commercial flocks within a vertically integrated broiler system and metadata from these and an additional 512 flocks within that system, the baseline bacterial microbiota was defined using 16S rRNA gene sequencing. The effects of age, sample type, flock, and successive flock cycles were compared, and results indicate a consistent, predictable, age-dependent bacterial microbiota, irrespective of flock. The tracheal bacterial microbiota of broilers was comprehensively defined, and Lactobacillus was the dominant bacterial taxon in the trachea. Numerous bacterial taxa were identified, which were strongly correlated with broiler chicken performance across multiple tissues. While many positively correlated taxa were identified, negatively associated potential pathogens were also identified in the absence of clinical disease, indicating that subclinical dynamics occur that impact performance. Overall, this work provides necessary baseline data for the development of effective antibiotic alternatives, such as probiotics, for sustainable poultry production.IMPORTANCE Multidrug-resistant bacterial pathogens are perhaps the greatest medical challenge we will face in the 21st century and beyond. Antibiotics are necessary in animal production to treat disease. As such, animal production is a contributor to the problem of antibiotic resistance. Efforts are underway to reduce antibiotic use in animal production. However, we are also challenged to feed the world's increasing population, and sustainable meat production is paramount to providing a safe and quality protein source for human consumption. In the absence of antibiotics, alternative approaches are needed to maintain health and prevent disease, and probiotics have great promise as one such approach. This work paves the way for the development of alternative approaches to raising poultry by increasing our understandings of what defines the poultry microbiome and of how it can potentially be modulated to improve animal health and performance.

Comparison of antibiotic supplementation versus a yeast-based prebiotic on the cecal microbiome of commercial broilers

Prebiotics are defined as fermentable food ingredients that selectively stimulate beneficial bacteria in the lower gastrointestinal tract of the host. The purpose of this study was to assess growth performance of broilers and the cecal microbial populations of an antibiotic, BMD50, supplemented birds compared to broiler chickens fed the prebiotic, Biolex^® MB40. Weight response data including feed conversion ratios (FCR), carcasses without giblets (WOG), wing, skin, white meat were collected during processing. Extracted DNA from cecal contents was utilized for microbiome analysis via an Illumina Miseq. In conclusion, white meat yield of Biolex^® MB40 supplemented group exhibited significant improvement compared to both negative control (NC) and BMD50 supplemented groups. In addition, antibiotic significantly decreased level of Lactobacillus in 2 wk compared to other groups. A significantly higher percentage of Campylobacter was observed from the 4 wk old birds treated with antibiotic BMD50 compared to the NC and prebiotic group. Retention of broiler performance and improvement of white meat yield suggest that the prebiotic MB40 appears to be a potential alternative to replace the antibiotic growth promoter.