Effects of yeast cell wall on growth performance, immune responses and intestinal short chain fatty acid concentrations of broilers in an experimental necrotic enteritis model

Colonic bacterial community responding to selenium-enriched yeast supplementation associated with improved gut mucus function in growing-finishing pigs

Selenium-enriched yeast (SeY), a high-quality organic source of selenium, enhances antioxidant activity and intestinal health in swine. This study aims to evaluate the effects of varying dietary SeY levels on intestinal morphology, epithelial mucus production, antioxidant activity, and colonic bacterial communities in growing-finishing pigs. Thirty 90-day-old Duroc×Landrace×Yorkshire growing-finishing pigs (average body weight of 54.37±2.13 kg) were randomly assigned to five treatment groups. The control group (CON) was fed a basal diet, while the other four groups were fed the basal diet supplemented with SeY at 0.3, 1, 3, and 5 mg/kg, respectively, for an 80-day of feeding trial. The results showed that the addition of SeY at 0.3 mg/kg increased villus height, villus height/crypt ratio, and mucus production in the ileum, as evidenced by the increase in goblet cell number and mucus thickness (P < 0.05). Furthermore, 0.3 mg/kg SeY up-regulated the mRNA expression levels of the MUC-1, claudin-1, occludin, and ZO-1 genes (P < 0.05). In contrast, high-dose SeY at 5 mg/kg resulting in damage to mucosal morphology. Ileal antioxidant activity of SOD and GSH-Px, and jejunal mRNA expression of GPX-1 and GPX-4, were higher in response to SeY (P < 0.05). Faecal Se excretion increased in SeY groups in a dose-dependent manner (P < 0.05). SeY led to a significant difference in beta diversity among treatment groups (P = 0.002) and led to a significant decrease in the concentrations of isobutyric and isovaleric acids when compared to the control group (P < 0.05). The acetate, propionate, butyrate, and total short-chain fatty acids were positively correlated with the biomarker genera Agathobacter (SeY at 0.3mg/kg), while isobutyrate and isovalerate were negatively correlated with biomarker genera Lactobacillus (SeY at 0.3mg/kg) (P < 0.05). Faecal accumulation of Se was positively correlated with the biomarker genera Alloprevotella (SeY at 3mg/kg) and Prevotellaceae_UCG-001 (SeY at 5mg/kg) and was negatively correlated with biomarker genera Agathobacter (SeY at 0.3mg/kg), Bacteroides (CON), and Faecalibacterium (CON) (P < 0.05). In conclusion, SeY doses of 0.3 mg/kg have beneficial effects on intestinal health, whereas prolonged SeY doses up to 5 mg/kg may compromise the intestinal mucus function in growing-finishing pigs.

Dietary supplementation of yeast polysaccharides enhance lamb growth performance by improving immune and intestinal barrier function and the abundance of cecal microbiota

Weaning stress can affect the growth performance and intestinal health of lambs. Yeast polysaccharides are green and safe feed additives that have been shown to improve growth performance and intestinal health in other animals. The aim of this study was to explore the effects of dietary yeast polysaccharides on the growth performance and intestinal health of weaned lambs. Twenty-four healthy lambs were randomly divided into four groups and fed different doses of yeast polysaccharides (Y) with a basal diet: 0 g/day (control, C), 0.5 g/day (low dose, LY), 1 g/day (medium dose, MY), and 2 g/day (high dose, HY). Results showed that the MY group had a significantly higher average daily gain and a lower feed-to-gain ratio than the control group. Yeast polysaccharide supplementation significantly increased the immunoglobin G (IgG), immunoglobin A (IgA), and β-defensin contents in serum, as well as the secretory immunoglobulin A (SIgA) content in the intestinal mucosa. It also enhanced intestinal villus development, increased the villus height-to-crypt depth ratio, and upregulated the mRNA and protein expression of Claudin1, Occludin, and ZO1. Cecal microbiota analysis revealed an increased relative abundance of Firmicutes, Ruminococcus, Clostridium, Butyrivibrio and Adlercreutzia, along with elevated volatile fatty acid levels. Taken together, these findings suggest that yeast polysaccharides improve growth performance, immune function and intestinal healthy in weaned lambs. Under the conditions of this experiment, 0.5-1 g/d is the optimal dose for production.

Effects of Dietary Supplementation with Yeast Hydrolysate on Immune Function, Fecal Short Chain Fatty Acids, and Intestinal Health in Cats

Yeast hydrolysate (YH) is rich in amino acids and other nutrients, and as a nutritional supplement it has been widely used in daily nutritional supplements for livestock. However, the role of YH in domestic pets, especially cats, has not yet been determined. The objective of this research was to study the effects of different concentrations of YH on the healthy cats. All cats were randomly divided into four treatments: the control group (T0, n = 6, without YH), treatment 1 (T1, the low concentration group, 0.8% of YH, n = 6), treatment 2 (T2, the middle concentration group, 1.5% of YH, n = 6), and treatment 3 (T3, the high concentration group, 4% of YH, n = 6), and the blood biochemistry, immune indexes and odorous substances in the feces, and microbiome of cats were determined on day 28. Our results showed that YH could increase the immunoglobulin G (IgG) level in the serum (p < 0.01) and reduce 3-methylindole content in the feces (p < 0.01). The acetic acid in the feces of T2 treatment (1.5%YH) was apparently increased compared to the control treatment (p < 0.05). The blood biochemistry indexes were not affected by the YH. Compared to the control group, there was no significant difference in the abundance at the phylum level. On the genus level, the abundance of g_Ruminocococcaceae and g_Lachnospiraceae, the beneficial bacteria in the gut, were decreased in the treatment T3 compared to treatment T1 (p < 0.05), but there was no significance between T1 and T2, which suggested that a high concentration of YH may be negative for gut health. So, the research showed that 1.5% of YH could be the best concentration for the improvement of immunity and gut health for cats.

Effects of graded yeast cell wall supplementation on growth performance, immunity and intestinal development of broiler chickens raised in floor pens for 42 days

This study was conducted to evaluate the effects of dietary supplementation of a novel soluble yeast cell wall (YCW) on growth performance, gut health, intestinal morphology, and immune response in broiler chickens for 42 days. A total of 480 one-day-old Cobb 500 male broilers were randomly assigned to four treatments with six replicates and each replicate of twenty broiler chickens: a control group (CON) without feed additive supplementation, and three groups supplemented with YCW at 0.025 % (YCW1), 0.050 % (YCW2), and 0.100 % (YCW3). Results showed that 0.025 % and 0.100 % YCW supplementation significantly increased (P < 0.05) final body weight (BW) and overall body weight gain (BWG) while reducing overall feed conversion ratio (FCR) compared to the CON group. The YCW supplementation also improved (P < 0.05) the balance of gut microbiota by increasing beneficial bacteria (Lactobacillus) and decreasing Salmonella, a potential foodborne pathogen in humans in the ceca. Although intestinal morphology was not significantly affected, YCW supplementation numerically increased the villus height: crypt depth ratio (VH:CD) compared to the CON group. Furthermore, YCW reduced the mRNA expression of pro-inflammatory cytokines (IL-1β and INF-γ) and tight junction protein claudin-1 (CLDN-1) (P < 0.05), suggesting balanced immune response and improved intestinal barrier function. In conclusion, the supplementation of soluble YCW in broiler diets positively influenced growth performance, gut microbiota composition, and immune response, demonstrating its potential as a viable alternative to antibiotics for improving broilers' health.

Mannan oligosaccharide as an alternative to infeed antibiotics to improve growth performance of broilers: a meta-analysis

1. The purpose of this meta-analysis was to evaluate the effect of mannan oligosaccharide (MOS) as an alternative to antibiotic growth promoters (AGP) on feed intake (FI), body weight gain (BWG), and feed conversion ratio (FCR) of broilers.2. Data from 75,594 broilers were extracted from 17 articles (19 trials) published between January 2010 and March 2023. The main criteria for the publication selection were as follows, at least three treatments applied (negative control group without MOS or AGP versus MOS or AGP supplementation), presence of performance results, and intra-experimental variation associated with the mean of response (such as standard error). Treatments were classified as control, MOS, or AGP, and adjusted means of treatment were compared. Additionally, the average daily gain (ADG) and average daily feed intake (ADFI) of each type of supplementation were calculated relative (Δ) to the control group (ΔADFI and ΔADG) and expressed as a percentage of the difference.3. Broilers receiving a diet supplemented with MOS had a 3.7% better BWG and 3% better FCR compared to the control diet (P < 0.001), but these variables were similar to the group receiving AGP supplementation. No significant difference was detected in FI among treatments (P > 0.050). The relationship between ΔADG and ΔADFI was linear for the MOS and AGP-supplemented group (P < 0.050). The ΔADG of broilers fed diets supplemented with MOS or AGP was 6.4% and 4.54% when ΔADFI was zero, respectively. The ΔADG of MOS increased by 0.58% for every 1% of increasing observed in ΔADFI. The corresponding value for the increased ΔADG for the AGP group was 0.69%.4. The results of this meta-analysis indicated that MOS supplementation is effective in increasing BWG and reducing FCR, similar to broilers fed a diet supplemented with AGP. Therefore, MOS is a safe and sustainable alternative for AGP-free poultry production.

A specific blend of prebiotics and postbiotics improved the gut microbiome of dogs with soft stools in the in vitro Simulator of the Canine Intestinal Microbial Ecosystem

The Simulator of the Canine Intestinal Microbial Ecosystem (SCIME) allows for the study of the long-term effects of food, supplements, or ingredients on the canine gut microbiome in a simulated proximal and distal colon. This model has been used to evaluate the impact of repeated administration of a test product blend composed of a mixture of baobab fruit pulp, acacia gum, heat-killed Lactobacillus helveticus HA-122, and specific fractions of selected inactivated yeast strains (including Saccharomyces cerevisiae AQP 12260 and AQP 12988 and Cyberlindnera jadinii AQP 12549), on the activity and composition of the gut microbiome of canine donors with soft stools. The SCIME colonic reactors were inoculated with fecal material from 3 different canine donors. After 2 d of stabilization, the 8-d parallel control/treatment period was initiated; reactors were fed with SCIME nutritional medium with or without test product. Changes in microbial metabolic activity were assessed by measuring levels of acetate, propionate, butyrate, lactate, branched short-chain fatty acids, and ammonium. Changes in microbial community composition were assessed using 16S-targeted Illumina sequencing. Overall, test product supplementation resulted in increased saccharolytic fermentation, as evidenced by increases in the health-promoting bacterial metabolites such as propionate (donor-dependent), acetate, and butyrate (donor-dependent) as well as increased abundances of several saccharolytic fermenting microbes, including Bifidobacterium. Conversely, proteolytic bacteria like Proteobacteria were reduced with the test product compared to control. Repeated supplementation with the test product was therefore able to induce-in vitro-a positive modulation of the microbiome originated from dogs with soft stools.

Dietary supplementation of prebiotic yeast Saccharomyces cerevisiae cell wall promotes growth performance and intestinal health in broiler chickens challenged with Clostridium perfringens

1. This study evaluated the effectiveness of yeast (Saccharomyces cerevisiae) cell wall (YCW) supplementation on the growth performance, carcase characteristics, serum biomarkers, liver function, ileal histology and microbiota of broiler chickens challenged with Clostridium perfringens (C. perfringens).2. In a 35-d trial, 240 chicks aged 1-d-old were randomly assigned to one of four treatment groups, each with 10 replicates:   control (CON) with no challenge or additives, challenged with C. perfringens (CHAL), CHAL and supplemented with YCW at either 0.25 g/kg (YCW0.25) or 0.5 g/kg (YCW0.5).3. In comparison to CON, the CHAL birds had reduced growth performance, survival rate, dressing percentage, breast meat yield, levels of total protein (TP), globulin (GLO), glucose (GLU), total antioxidant capacity (T-AOC) and total superoxide dismutase (T-SOD), as well as a decreased Lactobacillus population (P < 0.01). Additionally, this group showed elevated levels of glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), and C. perfringens count (P < 0.01). Compared to CHAL, the YCW0.25 or YCW0.5 groups had improved growth performance, survival rate, dressing percentage, breast meat yield, levels of TP, GLO, GLU, and T-AOC, as well as the activities of T-SOD, GOT, and GPT, villus height, villus surface area, villus height to crypt depth ratio, and the populations of both Lactobacillus and C. perfringens; (P < 0.01).4. The data suggested that YCW supplementation at either 0.25 or 0.50 g/kg can restore the growth performance of broiler chickens during a C. perfringens challenge.

Dietary supplementation with probiotics increases growth performance, improves the intestinal mucosal barrier and activates the Wnt/β-catenin pathway activity in chicks

BACKGROUND

Probiotics comprise effective feed additives that can replace antibiotics in animal livestock production. However, mono-strain probiotics appear less effective because of their instability. Therefore, the present study aimed to investigate dietary supplementation with compound probiotics (CPP) on growth performance, diarrhea rate and intestinal mucosal barrier, as well as the possible molecular mechanism, in chicks. In total, 360 1-day-old chicks of the Hy-Line Brown Chicks were randomly divided into the control group (CON, basal diet), chlortetracycline group (500 mg kg^-1 CTC) and compound probiotics group (1000 mg kg^-1 CPP, consisting of Bacillus subtilis, Bacillus licheniformis, Enterococcus faecium and yeast). The experiment period was 56 days.

RESULTS

The results showed that, in comparison with the CON group, CPP significantly increased the average daily feed intake and average daily gain of chicks and reduced diarrhea (P < 0.05). The probiotic group exhibited increased immune organ (i.e. spleen and thymus) mass and increased levels of serum immunoglobulin (Ig)A, IgM and IgG (P < 0.05) compared to the CTC group. In addition, the jejunal mass and morphology were improved in the probiotic group (P < 0.05). Moreover, CPP reinforced jejunal barrier function, as indicated by increased transepithelial electrical resistance, protein expression of occludin and claudin-1, and diamine oxidase levels in the jejunum (P < 0.05). Likewise, enhanced fluorescence signals of proliferating cell nuclear antigen-labeled mitotic cells and villin-labeled absorptive cells in the jejunum (P < 0.05) suggested that CPP promoted intestinal stem cells activity. Mechanistically, the Wnt/β-catenin signaling pathway, including β-catenin, TCF4, c-Myc, cyclin D1 and Lgr5, was amplified in the jejunum by CPP addition (P < 0.05).

CONCLUSION

The present study demonstrated that dietary supplementation with CPP reinforced the jejunal epithelial integrity by activating Wnt/β-catenin signaling and enhanced immune function in chicks. © 2023 Society of Chemical Industry.

Dietary yeast cell wall enhanced intestinal health of broiler chickens by modulating intestinal integrity, immune responses, and microbiota

This study was conducted to determine the effects of dietary yeast cell wall (YCW) on growth performance, intestinal health, and immune responses of broiler chickens. In a randomized completely block design (block: initial body weight), a total of 800 broilers (Ross 308; 45.18 ± 3.13 g of initial body weight) were assigned to 2 dietary treatments (40 birds/pen; 10 replicates/treatment) and fed for 5 wk: 1) a basal broiler diet based on corn-soybean meal (CON) and 2) CON + 0.05% dietary YCW. Growth performance was measured at intervals in 3 phase feed program. On the final day of the study, one bird per pen was randomly selected and euthanized for sample collection. Broilers fed YCW had decreased (P < 0.05) feed conversion ratio during the grower phase compared with those fed CON. The YCW increased (P < 0.05) villus height to crypt depth ratio in the duodenum, jejunum, and ileum compared with the CON. In addition, the YCW tended to higher (P < 0.10) number of goblet cells in the duodenum than in the CON. Broilers fed YCW had increased (P < 0.05) serum TGF- β1, ileal gene expression of the claudin family, and relative abundance of Lactobacillus, Prevotella, and Enterococcus compared with the CON, but decreased serum TNF-α (P < 0.05), IL-1β (P < 0.05), and IL-6 (P < 0.10), ileal gene expression of IL-6 (P < 0.05), and relative abundance of Clostridium (P < 0.05). The present study demonstrated that the addition of dietary YCW in broiler diets enhanced the intestinal health of broiler chickens and may be associated with modulated intestinal morphology and integrity by upregulating tight junction-related protein gene expression and modifying the ileal microbiota. In addition, dietary YCW modulated immune responses and inflammatory cytokine gene expression in the ileum.

Early-life β-glucan exposure enhances disease resilience of broiler chickens to a natural Clostridium perfringens infection

Necrotic enteritis (NE) is an economically important disease in poultry. Colonization by the opportunistic pathogen C. perfringens occurs early after hatch and induces host immune tolerance, which allows it to persist as part of the bird's commensal microflora. β-glucan, a yeast cell wall component, is well characterized for its immunomodulatory capacity, and is a strong driver of innate immune memory. In this study, we assessed the effectiveness of β-glucan to reduce severity of NE, when co-administered with heat-killed C. perfringens via intra-abdominal route at day 1 of age. We found that this early-life exposure in the presence of β-glucan did not reduce intestinal C. perfringens loads or lesion severity during a subsequent NE outbreak. However, it improved ileal morphology, prevented liver and spleen weight decline, and preserved feed efficiency in challenged birds. Molecular analyses revealed metabolic changes consistent with innate immune memory. Together, our results suggest that β-glucan can reduce the negative impacts of NE by influencing the context in which C. perfringens is first encountered.

Potential Probiotics Role in Excluding Antibiotic Resistance

Background. Antibiotic supplementation in feed has been continued for the previous 60 years as therapeutic use. They can improve the growth performance and feed efficiency in the chicken flock. A favorable production scenario could favor intestinal microbiota interacting with antibiotic growth promoters and alter the gut bacterial composition. Antibiotic growth promoters did not show any beneficial effect on intestinal microbes. Scope and Approach. Suitable and direct influence of growth promoters are owed to antimicrobial activities that reduce the conflict between host and intestinal microbes. Unnecessary use of antibiotics leads to resistance in microbes, and moreover, the genes can relocate to microbes including Campylobacter and Salmonella, resulting in a great risk of food poisoning. Key Findings and Conclusions. This is a reason to find alternative dietary supplements that can facilitate production, growth performance, favorable pH, and modulate gut microbial function. Therefore, this review focus on different nutritional components and immune genes used in the poultry industry to replace antibiotics, their influence on the intestinal microbiota, and how to facilitate intestinal immunity to overcome antibiotic resistance in chicken.

Impact of a Natural Fusarial Multi-Mycotoxin Challenge on Broiler Chickens and Mitigation Properties Provided by a Yeast Cell Wall Extract and a Postbiotic Yeast Cell Wall-Based Blend

Yeast cell wall-based preparations have shown efficacy against Aspergillus-based toxins but have lower impact against type-B trichothecenes. Presently, we investigated a combination of deoxynivalenol (DON), T-2 toxin (T2) and zearalenone (ZEA), and the effect of a yeast cell wall extract (YCWE) and a post-biotic yeast cell wall-based blend (PYCW) with the objectives of preventing mycotoxins’ negative effects in commercial broilers. A total of 720 one-day-old male Cobb broilers were randomly allocated to: (1) control diet, (aflatoxins 6 µg/kg; cyclopiazonic acid 15 µg/kg; fusaric acid 25 µg/kg; fumonisin B1 310 µg/kg); (2) Diet1 + 0.2% YCWE; (3) Diet1 + 0.2% PYCW; (4) Contaminated diet (3.0 mg/kg DON; 2.17 mg/kg 3-acetyldeoxynivalenol; 104 g/kg T2; 79 g/kg ZEA); (5) Diet4 + 0.2% YCWE; and (6) Diet4 + 0.2% PYCW. Naturally contaminated diets adversely affected performance, serum biochemistry, liver function, immune response, altered cecal SCFA goblet cell count and architecture of intestinal villi. These adverse effects were reduced in birds fed PYCW and to a lesser extent YCWE, indicating protection against toxic assault. PYCW yielded better production performance and stimulated liver function, with higher response to NDV and IBV vaccination. Furthermore, mycotoxins were found to affect production outputs when evaluated with the European poultry production efficiency factor compared to control or YCWE and PYCW supplemented treatments. Taken together, YCWE, when complemented with nutritional add-ons (PYCW), could potentiate the remediation of the negative effects from a multi mycotoxins dietary challenge in broiler birds.

Effects of dietary glucose oxidase on growth performance and intestinal health of AA broilers challenged by Clostridium perfringens

Arbor Acre (AA) broilers were used as the research object to investigate whether glucose oxidase (GOD) has preventive and relieving effects on necrotic enteritis. The experiment was designed as a factorial arrangement of 2 dietary treatments × 2 infection states. Chickens were fed a basal diet or a diet with 150 U/kg GOD, and were challenged with Clostridium perfringens (Cp) or sterile culture medium. In our study, Cp challenge led to intestinal injury, as evidenced by reducing the average daily gain and the average daily feed intake of AA broilers of 14 to 21 d (P < 0.05), increasing the intestinal jejunal lesion score (P < 0.05), reducing the jejunal villi height and villi height/crypt depth (P < 0.05), upregulating the mRNA expression levels jejunal IFN-γ (P < 0.05). The dietary GOD had no significant effects on the growth performance of each growth period, but significantly decreased the ileal pH, increased the height of villi and the ratio of villi height to crypt depth (P < 0.05) and the expression levels of Occludin and Zonula occludens-1 (ZO-1) at d 21. Moreover, dietary GOD and the Cp challenge significantly altered the composition of 21-d ileal microbiota. The Cp challenge decreased the relative abundance of genus Lactobacillus (P = 0.057), and increased the relative abundance of genus Romboutsia (P < 0.05) and genus Veillonella (P = 0.088). The dietary GOD tended to increase the relative abundance of genus Helicobacter (P = 0.066) and decrease the relative abundance of genus Streptococcus (P = 0.071). This study has shown that the supplementation of GOD could promote the integrity of intestinal barrier and the balance of ileal microbiota, but the effects of GOD on NE broilers and its application in actual production need to be further confirmed.

Compound Probiotics Improve Body Growth Performance by Enhancing Intestinal Development of Broilers with Subclinical Necrotic Enteritis

The aim of this study is to explore whether or not the combined application of BS15 and H2 is capable to have a more effective control effect on SNE in broilers. A total of 240 1-day-old female chickens were randomly divided into 5 groups: (a) basal diet in negative control group (NC group); (b) basal diet + SNE infection (coccidiosis vaccine + CP) (PC group); (c) basal diet + SNE infection + H2 pre-treatment (BT group); (d) basal diet + SNE infection + BS15 pre-treatment (LT group); and (e) basal diet + SNE infection + H2 pre-treatment + BS15 pre-treatment (MT group). The results showed the MT group had the most positive effect on inhibiting the negative effect of growth performance at 42 days of age. In the detection of the NC, PC, and MT group indicators at 28 days of age, we found that MT group significantly promoted ileum tissue development of broilers, and the ileum of broilers in the MT group formed a flora structure different from NC and PC, although it was found that the MT group had no effect on the butyrate level in the cecum, but it could affect the serum immune level, such as significantly reducing the level of pro-inflammatory cytokine IL-8 and increasing the content of immunoglobulin IgM and IgG. In conclusion, the composite preparation of Lactobacillus johnsonii BS15 and Bacillus licheniformis H2 could effectively improve the growth performance against SNE broilers, which is possibly caused by the improvement of the immune levels, the reduction of inflammation levels, and the promotion of the intestinal development.

Role of Yeast and Yeast-Derived Products as Feed Additives in Broiler Nutrition

Antibiotic resistance is looming problem in broiler production globally and there has been an increasing interest to look for sustainable alternatives to antibiotics. Yeast and its derived products are recognized as potential feed additives because of their beneficial impacts on poultry. Particularly, yeast exhibited positive effects on the humoral immunity by increasing serum immunoglobulin (Ig) A levels. Moreover, yeast and its products showed immune adjuvant-like properties that helped the broilers chicken to develop faster and stronger innate immune response under pathogenic challenges. Use of yeast and its products as prebiotic/probiotic improves the gut architecture mainly by improving the gut development and gut microbiome, reduction in colonization of pathogens through competitive exclusion, binding of toxins and enhancing digestion and absorption of nutrients. These unique properties of yeast and yeast products enhance animal welfare and productivity; warrant them to be used as a promising feed additive. This article, therefore, provides insights into the functional role of yeast and its products in the broiler diets and highlights its importance as a commercially viable alternative of synthetic antibiotic growth promoters in the broiler feed industry.

Centennial Review: Recent developments in host-pathogen interactions during necrotic enteritis in poultry

Necrotic enteritis (NE) is a significant enteric disease in commercial poultry with considerable economic effect on profitability manifested by an estimated $6 billion in annual losses to the global industry. NE presents a unique challenge, being a complex enteric disease that often leads to either clinical (acute) or subclinical (chronic) form. The latter typically results in poor performance (reduced feed intake, weight gain and eventually higher feed conversion ratio [FCR]) with low mortality rates, and represents the greatest economic impact on poultry production. The use of antibiotic growth promoters (AGPs) has been an effective tool in protecting birds from enteric diseases by maintaining enteric health and modifying gut microbiota, thus improving broilers’ production efficiency and overall health. The removal of AGPs presented the poultry industry with several challenges, including reduced bird health and immunity as well as questioning the safety of poultry products. Consequently, research on antibiotic alternatives that can support gut health was intensified. Probiotics, prebiotics, essential oils, and organic acids were among various additives that have been tested for their efficacy against NE with some being effective but not to the level of AGPs. The focus of this review is on the relationship between NE pathogenesis, microbiome, and host immune responses, along with references to recent reviews addressing production aspects of NE. With a comprehensive understanding of these dynamic changes, new and programmed strategies could be developed to make use of the current products more effectively or build a stepping stone toward the development of a new generation of supplements.

Structure, preparation, modification, and bioactivities of β-glucan and mannan from yeast cell wall: A review

In order to solve the antibiotic resistance, the research on antibiotic substitutes has received an extensive attention. Many studies have shown that β-glucan and mannan from yeast cell wall have the potential to replace antibiotics for the prevention and treatment of animal diseases, thereby reducing the development and spread of antibiotic-resistant bacterial pathogens. β-Glucan and mannan had a variety of biological functions, including improving the intestinal environment, stimulating innate and acquired immunity, adsorbing mycotoxins, enhancing antioxidant capacity, and so on. The biological activities of β-glucan and mannan can be improved by chemically modifying its primary structure or reducing molecular weight. In this paper, the structure, preparation, modification, and biological activities of β-glucan and mannan were reviewed, which provided future perspectives of β-glucan and mannan.

Necrotic enteritis challenge regulates peroxisome proliferator-1 activated receptors signaling and β-oxidation pathways in broiler chickens

Necrotic enteritis (NE) is an important enteric disease in poultry and has become a major concern in poultry production in the post-antibiotic era. The infection with NE can damage the intestinal mucosa of the birds leading to impaired health and, thus, productivity. To gain a better understanding of how NE impacts the gut function of infected broilers, global mRNA sequencing (RNA-seq) was performed in the jejunum tissue of NE challenged and non-challenged broilers to identify the pathways and genes affected by this disease. Briefly, to induce NE, birds in the challenge group were inoculated with 1 mL of Eimeria species on day 9 followed by 1 mL of approximately 10⁸ CFU/mL of a NetB producing Clostridium perfringens on days 14 and 15. On day 16, 2 birds in each treatment were randomly selected and euthanized and the whole intestinal tract was evaluated for lesion scores. Duodenum tissue samples from one of the euthanized birds of each replicate (n = 4) was used for histology, and the jejunum tissue for RNA extraction. RNA-seq analysis was performed with an Illumina RNA HiSeq 2000 sequencer. The differentially expressed genes (DEG) were identified and functional analysis was performed in DAVID to find protein–protein interactions (PPI). At a false discovery rate threshold <0.05, a total of 377 DEG (207 upregulated and 170 downregulated) DEG were identified. Pathway enrichment analysis revealed that DEG were considerably enriched in peroxisome proliferator-activated receptors (PPAR) signaling (P < 0.01) and β-oxidation pathways (P < 0.05). The DEG were mostly related to fatty acid metabolism and degradation (cluster of differentiation 36 [CD36], acyl-CoA synthetase bubblegum family member-1 [ACSBG1], fatty acid-binding protein-1 and -2 [FABP1] and [FABP2]; and acyl-coenzyme A synthetase-1 [ACSL1]), bile acid production and transportation (acyl-CoA oxidase-2 [ACOX2], apical sodium–bile acid transporter [ASBT]) and essential genes in the immune system (interferon-, [IFN-γ], LCK proto-oncogene, Src family tyrosine kinase [LCK], zeta chain of T cell receptor associated protein kinase 70 kDa [ZAP70], and aconitate decarboxylase 1 [ACOD1]). Our data revealed that pathways related to fatty acid digestion were significantly compromised which thereby could have affected metabolic and immune responses in NE infected birds.

Yeast cell wall product enhanced intestinal IgA response and changed cecum microflora species after oral vaccination in chickens

The study was designed to explore the effect of a commercial yeast cell wall product (YP) on chicken intestinal IgA response and cecum microbiome after oral vaccination. Chickens were fed with YP during the experiments and orally immunized with live Newcastle disease virus (NDV) vaccine at 2 wk of age. Then, the animals were sacrificed, and samples were collected to measure the indicators of hemagglutination inhibition (HI), IgA response, IgA + cells, and cecum microbiome populations. The results showed that supplement of YP significantly enhanced serum NDV HI titer, intestinal NDV-specific secretory IgA, and intestinal IgA + cells. The sequencing results revealed that obviously increased relative abundance of Ruminococcaceae and decreased population of Bacteroidaceae in cecum were found in YP group. In summary, YP supplementation in diet enhanced intestinal IgA response to NDV vaccination by oral route and modulated the cecum microbiota to the advantage of the host in chickens.

Prospects of yeast based feed additives in poultry nutrition: Potential effects and applications

Yeast and its derivatives are extensively utilized as feed additives in poultry industry owing to their desirable health and growth promoting effects. Exhaustive number of studies had reported positive effects of yeast based additives on growth, meat quality, immunity, antioxidant status, and gastrointestinal functions in poultry birds. Owing to their prebiotic/probiotic properties, they also play significant role in gut development and modulation of gut microbiome by favouring beneficial microbes while reducing colonization of pathogenic microbes by competitive exclusion. They also possess effective potential for binding of dietary toxins in addition to improving digestion and utilization of nutrients. Moreover, yeast based additives have exhibited desirable effects on humoral immunity by increasing serum immunoglobulin (Ig) A levels. These additives have been also used as immune adjuvants to boost innate immune response under any pathogenic challenges in birds. Due to their diverse biological activities, yeast products are potentially capable for immune hemostasis by mediating balance between pro- and anti-inflammatory activities. These unique properties of yeast based products make them promising feed additive to promote health and productivity leading to efficient poultry production. Yeast can be supplemented in poultry diets @ 5.0–10.0 g/kg of feed. Numerous studies had reported significant improvement in body weight gain (3 to 8%) and FCR (1.6 to 12%) in broilers in response to supplementation of yeast based additives. Moreover, yeast supplementation also improved hemoglobin (Hb g/dl) levels up to 2.59 to 6.62%, total protein (>0.69%) while reducing serum cholesterol (mg/dl) up to 3.68 to 13.38%. Despite the potential properties and beneficial effects, use of yeast and its derivatives as feed additives in poultry industry is not matching its inherent potential due to many reasons. This review aims to highlight the importance and potential role of yeast and its products as natural growth promoter to replace in feed antibiotics to address the issues of antibiotic residues and microbial resistance. This article provides insights on functional role of yeast based additives in poultry diets and their importance as commercially viable alternatives of antibiotic growth promoters in poultry feed industry.

Dietary supplementation of yeast cell wall improves the gastrointestinal development of weaned calves

The purpose of this study was to investigate the potential benefits of yeast cell wall (YCW) on the gastrointestinal development of weaned calves. Twenty healthy Holstein male calves (BW = 92 ± 8.29 kg and 60 ± 5 d of age) were randomly allocated into 2 groups: CON with no YCW, and YCW (accounted for 0.16% of the basal diet). The dietary concentrate-to-roughage ratio was 40:60. All the calves were fed regularly twice a day at 09:00 and 16:00 and had free access to water. The experiment lasted for 60 d. The results showed that calves fed YCW showed higher (P < 0.05) length, width, and surface area of papillae in the ventral sac of the rumen as compared to CON. For the dorsal sac of the rumen, the muscularis thickness was thicker (P < 0.05) in the YCW group when compared with CON group. The villus height of YCW calves was higher (P < 0.05) than that of CON in the ileum. Calves supplemented with YCW also showed a higher (P < 0.05) villus height-to-crypt depth ratio in the ileum. The YCW calves exhibited a greater (P < 0.05) thickness of the wall in the duodenum and jejunum. Calves supplemented with YCW improved (P < 0.05) the claudin 1 mRNA expression in the ileum and occludin mRNA expression in the jejunum and ileum. The YCW increased (P < 0.05) the contents of secretory immunoglobulin A in the jejunum and ileum of calves. In conclusion, dietary supplementation with YCW could improve the gastrointestinal development of weaned calves.

Effect of dietary supplementation with yeast cell wall extracts on performance and gut response in broiler chickens

Background

The dietary supplementation of yeast cell wall extracts (YCW) has been found to reduce pathogenic bacteria load, promote immunoglobulin production, prevent diseases by pro-inflammatory responses, and alter gut microbiota composition. This study evaluated growth and slaughter results, health, gut morphology, immune status and gut transcriptome of 576 male chickens fed two diets, i.e. C (control) or Y (with 250-500 g/t of YCW fractions according to the growth period). At 21 and 42 d the jejunum of 12 chickens per diet were sampled and stained with hematoxylin/eosin for morphometric evaluation, with Alcian-PAS for goblet cells, and antibodies against CD3+ intraepithelial T-cells and CD45+ intraepithelial leukocytes. The jejunum sampled at 42 d were also used for whole-transcriptome profiling.

Results

Dietary YCW supplementation did not affect final live weight, whereas it decreased feed intake (114 to 111 g/d; P ≤ 0.10) and improved feed conversion (1.74 to 1.70; P ≤ 0.01). Regarding the gut, YCW supplementation tended to increase villi height (P = 0.07); it also increased the number of goblet cells and reduced the density of CD45+ cells compared to diet C (P < 0.001). In the gut transcriptome, four genes were expressed more in broilers fed diet Y compared to diet C, i.e. cytochrome P450, family 2, subfamily C, polypeptide 23b (CYP2C23B), tetratricopeptide repeat domain 9 (TTC9), basic helix-loop-helix family member e41 (BHLHE41), and the metalloreductase STEAP4. Only one gene set (HES_PATHWAY) was significantly enriched among the transcripts more expressed in broilers fed diet Y. However, a total of 41 gene sets were significantly over-represented among genes up-regulated in control broilers. Notably, several enriched gene sets are implicated in immune functions and related to NF-κB signaling, apoptosis, and interferon signals.

Conclusions

The dietary YCW supplementation improved broiler growth performance, increased gut glycoconjugate secretion and reduced the inflammatory status together with differences in the gut transcriptome, which can be considered useful to improve animal welfare and health under the challenging conditions of intensive rearing systems in broiler chickens.

Modulation of SBD-1 expression by Saccharomyces cerevisiae cell wall components in ovine ruminal epithelial cells

The ovine rumen is an immune interface with the external environment, participating in host defence responses. Ovine ruminal epithelial cells (ORECs) not only have a physical barrier function, but also secrete sheep β-defensin-1 (SBD-1), which plays a key role in innate and adaptive immunity. Prebiotics are potential alternatives to infeed antibiotics. Saccharomyces cerevisiae cell wall (S.c.CW) is rich in prebiotics, which play roles in improving the growth performance of animals and regulating immunity. Here, we investigated whether S.c.CW induces SBD-1 expression in ORECs, as well as the underlying mechanism. The regulatory mechanisms of S.c.CW-induced up-regulation of SBD-1 were determined using quantitative real-time PCR, enzyme-linked immunosorbent assay, and western blotting. S.c.CW significantly increased the expression of Toll-like receptor 2 (TLR2) and nuclear factor-kappa B (NF-κB), but had no effect on TLR4 expression. TLR2, MyD88, and NF-κB inhibition attenuated the induction of SBD-1 expression by S.c.CW. However, TLR4 inhibition only resulted in attenuated SBD-1 mRNA, having no effect on SBD-1 protein expression. Thus, we conclude that S.c.CW can induce SBD-1 expression and that this induction is regulated by the TLR2-MyD88-NF-κB pathway.

Utility of Feed Enzymes and Yeast Derivatives in Ameliorating Deleterious Effects of Coccidiosis on Intestinal Health and Function in Broiler Chickens

Coccidiosis induced necrotic lesions impair digestive capacity and barrier function in concurrence with increased risks for secondary bacterial infections. The industry has been successful in controlling coccidiosis with anticoccidials and vaccination. However, concerns over Eimeria species resistant to anticoccidials, gaps in vaccination and restriction on antibiotics is stimulating research and application of alternative and/or complimentary strategies for coccidiosis control. The aim of this paper is to appraise literature on the utility of feed enzymes and yeast derivatives in modulating coccidiosis. Feed enzymes can complement endogenous enzymes (protease, amylase, and lipase) that may become insufficient in coccidiosis afflicted birds. Coccidiosis in the upper small intestine creates conditions that enhances efficacy of phytase and there are reports indicating supplemental phytase can mitigate the negative impact of coccidiosis on bone quality. Increase in intestinal short chain fatty acids due supplemental fiber degrading enzymes has been linked with reduced survivability of Eimeria. There is evidence whole yeast (live or dead) and derivatives can modulate coccidiosis. Immunomudulation properties of the yeast derivatives have been shown to enhance cellular and humoral immunity in Eimeria challenge models which is critical for effectiveness of coccidial vaccination. Moreover, yeast nucleotides have been shown to be beneficial in stimulating healing of intestinal mucosal surface. Other novel work has shown that certain yeast cells can produce derivatives with anticoccidial compounds effective in attenuating oocysts shedding. Yeast cell surface has also been shown to be an effective oral Eimeria vaccine delivery vehicle. Overall, while further refinement research is warranted to address inconsistencies in responses and commercial application, there is evidence feed enzymes and yeast derivatives could complement strategies for maintaining intestinal function to bolster growth performance in broilers compromised with coccidiosis. However, broilers receive diets containing several feed additives with distinct mode of actions and yet there is dearth of empirical data on the expected responses.Future evaluations should consider combinations of additives to document animal responses and potential synergies.

Effect of supplemental yeast cell walls on growth performance, gut mucosal glutathione pathway, proteolytic enzymes and transporters in growing broiler chickens

This study aimed to investigate the effect of supplemental yeast cell walls (YCW) on growth performance, gut mucosal glutathione pathway, proteolytic enzymes, and transporters in broiler chickens from 1 to 21 d of age. One-day-old broiler chickens (n = 480) were randomly allocated to 4 treatments with 6 replicates of 20 chicks each for diets containing YCW at 0, 0.5, 1.0, and 1.5 g/kg. The results showed that YCW supplementation increased (P < 0.05) ADFI and ADG by 15.3% and 16.0%, respectively, and the 2 higher doses of YCW had greater effects (P < 0.05) than the lower dose. For the glutathione pathway in the duodenal mucosa, the levels of reduced glutathione and glutathione reductase in the YCW treatments were increased (P < 0.05) by 15.6% and 17.4%, respectively, but glutathione S-transferases was not affected. Similarly, the YCW increased (P < 0.05) the mucosal activities of trypsin, dipeptidyl, and leucine aminopeptidase by 12.4%, 5.5%, and 17.3%, respectively, and the mRNA profiles of neutral, cationic, and oligopeptide transporters by 62.5%, 69.1%, and 11.5%, respectively. The YCW also increased (P < 0.05) the concentrations of Thr, Met, Ile, Leu, Lys, Arg, and Tyr in the blood by 8.8% to 39.2%. Additionally, the ADFI, ADG, reduced glutathione, trypsin, dipeptidyl aminopeptidase, leucine aminopeptidase, and cationic amino acid transporter increased linearly and quadratically (P < 0.05) with YCW supplementation. The results suggest that YCW supplementation can beneficially modulate intestinal glutathione pathway, proteolytic enzyme activity, and nutrient transport in growing animals.

Eubiotics for Food Security at Farm Level: Yeast Cell Wall Products and Their Antimicrobial Potential Against Pathogenic Bacteria

The population increase in the last century was the first cause of the industrialization of animal productions, together with the necessity to satisfy the high food demand and the lack of space and land for the husbandry practices. As a consequence, the farmers moved from extensive to intensive agricultural systems and introduced new practices, such as the administration of antimicrobial drugs. Antibiotics were then used as growth promoters and for disease prevention. The uncontrolled and continuous use of antibiotics contributed to the spread of antibiotic resistance in animals, and this had adverse impacts on human health. This emergence led the European Union, in 2003, to ban the marketing and use of antibiotics as growth promoters, and for prophylaxis purposes from January 2006. This ban caused problems in farms, due to the decrease in animal performances (weight gain, feed conversion ratio, reproduction, etc.), and the rise in the incidence of certain diseases, such as those induced by Clostridium perfringens, Salmonella, Escherichia coli, and Listeria monocytogenes. The economic losses due to the ban increased the interest in researching alternative strategies for the prophylaxis of infectious diseases and for health and growth promotion, such as feed additives. Yeast-based materials, such as cell wall extract, represent promising alternatives to antibiotics, on the base of their prebiotic activity and their claimed capacity to bind enteropathogenic bacteria. Several authors reported examples of the effectiveness of yeast cell wall products in adsorbing bacteria, but there is a lack of knowledge on the mechanisms involved in this interaction. The purpose of this review is to provide an overview of the current approaches used for the control of pathogenic bacteria in feed, with a particular focus on the use of yeast-derived materials proposed to control zoonoses at farm level, and on their effect on animal health.