Effects of yeast cell walls on performance and immune responses of cyclosporine A-treated, immunosuppressed broiler chickens

Dietary Kluyveromyces marxianus hydrolysate alters humoral immunity, jejunal morphology, cecal microbiota and metabolic pathways in broiler chickens raised under a high stocking density

This study investigated the impact of dietary supplementation with hydrolyzed yeast (Kluyveromyces marxianus) on growth performance, humoral immunity, jejunal morphology, cecal microbiota and metabolic pathways in broilers raised at 45 kg/m2. A total of 1,176 mixed sex 1-day-old Ross 308 broilers were distributed into 42 pens and randomly assigned to either the control group, the control + 250 g hydrolyzed yeast (HY)/ton, 250HY group, or the control + 500 g HY/ton, 500HY group for 42 d. HY did not affect growth performance. However, HY reduced (P < 0.05) mortality at 25 to 35 d. Dietary HY lowered the heterophil/lymphocyte ratio and enhanced the villus height/crypt depth ratio and Newcastle disease titer (P < 0.05). Compared with HY250 and the control, HY500 upregulated (P < 0.05) IL-10. HY enhanced the α diversity, inferring the richness and evenness of the ceca microbiota. HY500 had greater β diversity than the control (P < 0.05). Six bacterial phyla, namely, Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria, Verrucomicrobia, and Cyanobacteria, were found. The relative abundance of Firmicutes was greater in the HY500 treatment group than in the HY250 and control groups. HY decreased the abundance of Actinobacteria. HY supplementation altered (P < 0.05) the abundance of 8 higher-level taxa consisting of 2 classes (Bacilli and Clostridia), 1 order (Lactobacillales), 1 family (Streptococcaceae), and five genera (Streptococcus, Lachnospiraceae_uc, Akkermansiaceae, PACO01270_g, and LLKB_g). HY500 improved (P < 0.05) the abundance of Bacilli, Clostridia, Lactobacillales, Streptococcaceae, Streptococcus, PACO01270_g, and Lachnospiraceae_uc, while HY250 enhanced (P < 0.05) the abundance of Akkermansiaceae and LLKB_g. HY improved the abundance of Lactobacillus and Akkermansia spp. Minimal set of pathway analyses revealed that compared with the control, both HY250 and HY500 regulated 20 metabolic pathways. These findings suggest that dietary K. marxianus hydrolysate, especially HY500, improved humoral immunity and jejunal morphology and beneficially altered the composition and metabolic pathways of the cecal microbiota in broilers raised at 45 kg/m2.

Supplementation with organic yeast-derived selenium provides immune protection against experimental necrotic enteritis in broiler chickens

Necrotic enteritis (NE) is a potentially fatal poultry disease that causes enormous economic losses in the poultry industry worldwide. The study aimed to evaluate the effects of dietary organic yeast-derived selenium (Se) on immune protection against experimental necrotic enteritis (NE) in commercial broilers. Chickens were fed basal diets supplemented with different Se levels (0.25, 0.50, and 1.00 Se mg/kg). To induce NE, Clostridium perfringens (C. perfringens) was orally administered at 14 days of age post hatch. The results showed that birds fed 0.25 Se mg/kg exhibited significantly increased body weight gain compared with the non-supplemented/infected birds. There were no significant differences in gut lesions between the Se-supplemented groups and the non-supplemented group. The antibody levels against α-toxin and NetB toxin increased with the increase between 0.25 Se mg/kg and 0.50 Se mg/kg. In the jejunal scrapings and spleen, the Se-supplementation groups up-regulated the transcripts for pro-inflammatory cytokines IL-1β, IL-6, IL-8, iNOS, and LITAF and avian β-defensin 6, 8, and 13 (AvBD6, 8 and 13). In conclusion, supplementation with organic yeast-derived Se alleviates the negative consequences and provides beneficial protection against experimental NE.

Effects of rearing system and antibiotic treatment on immune function, gut microbiota and metabolites of broiler chickens

BACKGROUND

In China, cage systems with a high space utilization have gradually replaced ground litter systems, but the disease incidence of chickens in cages is higher. Broilers in the ground litter pens may be stimulated by more environmental microbes during the growth process and show strong immune function and status, but knowledge of which microbes and their metabolites play an immunomodulatory role is still limited. This study aimed to explore the differences and correlations in the immune function, gut microbiota and metabolites and the importance of gut microbiota of broilers raised in cages and ground litter pens.

METHODS

The experiment involved a 2 × 2 factorial arrangement, with rearing systems (cages or ground litter pens) and antibiotic treatment (with or without broad-spectrum antibiotics in drinking water) as factors.

RESULTS

The results showed that, compared with the cage group, the ground litter broilers had stronger nonspecific immune function (Macrophages% and NO in blood), humoral immune function (IgG in blood, LPS stimulation index in ileum) and cellular immune function (T%, Tc%, ConA stimulation index and cytokines in blood). Antibiotic (ABX) treatment significantly reduced nonspecific immune function (Macrophages% and NO in blood, iNOS and Mucin2 mRNA expression in ileum), humoral immune function (IgG in blood and sIgA in ileum) and cellular immune function (T% and cytokines in blood, Th and Tc ratio, TLRs and cytokines mRNA expression in ileum). Furthermore, the ground litter broilers had higher α diversity of microbiota in ileum. The relative abundance of Staphylococcus, Jeotgalicoccus, Jeotgalibaca and Pediococcus in the ileum of ground litter broilers were higher. ABX treatment significantly reduced the α diversity of ileal microbiota, with less Chloroplast and Mitochondria. In addition, the levels of acetic acid, isobutyric acid, kynurenic acid and allolithocholic acid in the ileum of ground litter broilers were higher. Spearman correlation analysis showed that Jeotgalibaca, Pediococcus, acetic acid, kynurenic acid and allolithocholic acid were related to the immune function.

CONCLUSIONS

There were more potential pathogens, litter breeding bacteria, short-chain fatty acids, kynurenine, allolithocholic acid and tryptophan metabolites in the ileum of broilers in ground litter pens, which may be the reason for its stronger immune function and status.

Enzymatically treated yeast bolstered growth performance of broiler chicks from young broiler breeders linked to improved indices of intestinal function, integrity, and immunity

Older breeder chicks (OBC) are heavier and robust at hatch than younger breeder chicks (YBC). However, the implications of broiler breeder age on chick intestinal function and the role of functional feedstuffs are unexplored. We evaluated the effects of broiler breeder age and the impact of feeding YBC enzymatically treated yeast on growth, nutrient utilization, and indices of intestinal function. Fertile Ross 708 eggs: 2,250 (56.5 ± 3.4g) from 30-wk-old (YBC) and 550 (64.2 ± 4.2 g) from 47-wk-old (OBC) were hatched and placed in 48 pens (44 chicks/pen) containing equal males and females for growth and intestinal function evaluation and 36 cages (5 chicks/cage) for metabolizable energy (AME). Five corn and soybean meal-based diets were formulated to contain 0, 0.05, 0.10, 0.20, and 0.40% HY40 for a 3-phase feeding program (starter: days 0–10, grower: days 11–24, and finisher; days 25–42). Grower phase diets also contained a 0.3% TiO₂ indigestible marker. The diets were allocated within YBC in a completely randomized block design (n = 8 for pens; n = 6 for cages). The OBC were fed a 0% yeast diet. Feed and water were provided freely; BW and feed intake were monitored, and excreta samples were collected on days 17 to 21 for apparent retention (AR). Birds were necropsied for plasma, jejunal tissues, organs weight, and ceca digesta. The OBC were heavier (P < 0.01) than YBC at hatch. Final BW of OBC and YBC fed, ≥0.10% yeast, was similar (P > 0.05). The OBC had similar FCR (P > 0.05) to YBC fed 0 to 0.10% yeast but higher (P = 0.003) than for YBC fed ≥0.20% yeast. Jejunal villi height to crypt depth ratio (VCR) and IgA were higher in OBC than 0% yeast (P = 0.01). Yeast increased VCR, bursa weight, jejunal, and plasma IgA (P = 0.01). The YBC fed ≥0.10% yeast had higher (P < 0.05) AR of crude protein, and gross energy than OBC and YBC fed 0 or 0.05% yeast. In conclusion, yeast improved YBC performance to the level of OBC linked to improved intestinal function, integrity, and immunity.

Comparison and Correlation Analysis of Immune Function and Gut Microbiota of Broiler Chickens Raised in Double-Layer Cages and Litter Floor Pens

This study aimed to compare the immune function and gut microbiota between double-layer caged and litter floor pen-raised broiler chickens. Eighty meaty male chicks were selected and divided into cage group and litter floor group, with 20 replicates in each group. The broilers were raised in the same chicken house. The rearing density of the two rearing systems was same. The broilers were sampled on days 13 and 34. The results showed that compared with the cage group, the litter floor broilers had worse growth performance (23.24% increase in feed conversion ratio) in the early stage; better slaughter performance at day 42; stronger peripheral immune function (including higher lysozyme activity, T-cell ratio, Th-cell ratio, Tc-cell ratio, CD4/CD8, IL-10, B-cell ratio, IgG and IgA levels; and spleen immune-related gene expression); and stronger intestinal immune function (including higher ileum CD80, AvBD2, Mucin2, NF-κB, IL-8, IFN-γ/IL-4, and IgA mRNA expression levels and ileal mucosa sIgA levels). Compared with the cage group, the alpha diversity of ileum microbiota of the litter floor broilers was higher, and the relative abundance levels of litter breeding bacteria (Facklamia, Globicatella, and Jeotgalicoccus) and potential pathogenic bacteria (Streptococcus and Staphylococcus) were higher (P < 0.05). Through Spearman correlation analysis, it was found that enriched microbes in the ileum of litter floor broilers were positively correlated with immune function. In summary, compared with cage broilers, litter floor broilers had more potential pathogenic bacteria and litter breeding bacteria in the ileum, which may be one of the important reasons for the stronger immune function status. IMPORTANCE In China, the three-dimensional rearing system (cage) for broilers has gradually become a trend. In production, it was found that the incidence of disease in broiler chickens raised in cage systems was significantly higher than that of ground litter. Given that broilers raised on ground litter systems may be exposed to more environmental microbes, it is important to understand whether the rearing environment affects the function and status of the host immune system by altering the gut microbiota. In this study, rearing environment-derived gut microbes associated with stronger immune function in ground litter broilers were provided, which will provide new insights into strategies to target gut microbes to promote immune function and status in broilers raised in cages.

Effects of Dietary Astragalus Polysaccharide Supplementation on the Th17/Treg Balance and the Gut Microbiota of Broiler Chickens Challenged With Necrotic Enteritis

This study aimed to investigate the effects of dietary astragalus polysaccharide (APS) supplementation on the immune function, gut microbiota and metabolism of broiler chickens challenged with necrotic enteritis (NE). Two hundred forty Arbor Acres broiler chicks (one day old) were randomly assigned using a 2 × 2 factorial arrangement into two groups fed different levels of dietary APS (0 or 200 ppm of diet) and two disease challenge groups (control or NE challenged). The results showed that NE infection significantly increased FCR, mortality rate, Th17/Treg (Th17 cells% in blood and ileum, Th17/Treg, IL-17 and IL-17/IL-10 in blood), NO, lysozyme activity and IL-1β in blood, intestinal immune cell proportion and activity (Tc%, Treg% and monocyte phagocytic activity in ileum), intestinal inflammatory cytokines (TLR2, NF-κB, TNF-α and IL- 6) gene expression levels, and the number of Clostridium perfringens in cecum. NE infection significantly reduced body weight gain, thymus index, lymphocyte proliferation activity in blood and ileum, villus height and V/C in jejunum, Th cells% and Mucin2 gene expression in ileum. Dietary APS supplementation significantly increased body weight, feed intake, proportion of immune cells (T cells in blood and Tc, Treg in ileum), lymphocyte proliferation activity, V/C in jejunum, and ZO-1 gene expression in ileum. Dietary APS supplementation significantly reduced FCR and mortality rate, Th17/Treg, Th17%, intestinal pathology scores, intestinal inflammatory cytokine gene expression levels, and the number of Clostridium perfringens in cecum. In addition, broilers challenged with NE significantly increased Staphylococcus and Turicibacter and reduced α diversity of microbiota in ileum. Dietary APS supplementation significantly increased α diversity, Romboutsia, Halomonas, propionic acid, butyric acid, formononetin, taurine, cholic acid and equol and downregulated uric acid, L-arginine and serotonin in ileum. Spearman’s correlation analysis revealed that Romboutsia, Turicibacter, Staphylocpccus, Halomonas, Streptococcus, Escherichia-Shigella, Prevotella, uric acid, L-arginine, jerivne, sodium cholate and cholic acid were related to inflammation and Th17/Treg balance. In conclusion, APS alleviated intestinal inflammation in broilers challenged with NE probably by regulating intestinal immune, Th17/Treg balance, as well as intestinal microbiota and metabolites.

Effects of yeast hydrolysate on growth performance, serum parameters, carcass traits, meat quality and antioxidant status of broiler chickens

BACKGROUND

Yeast hydrolysate (YH) has multiple salutary biological activities. Nevertheless, the application of YH in broiler production is limited. This study was conducted to evaluate the protective effects of YH derived from Saccharomyces cerevisiae by exploring growth performance, serum parameters, organs relative weight, carcass traits, meat quality and antioxidant status of broilers.

RESULTS

Supplementing YH linearly and quadratically improved (P < 0.05) body weight gain and gain-to-feed ratio compared to that in the control group. Triglycerides, low-density lipoprotein cholesterol and total cholesterol in serum, the decline in pH and cooking loss of breast muscle, and malonaldehyde concentration in serum and liver were decreased linearly and/or quadratically by YH (P < 0.05), whereas high-density lipoprotein cholesterol in serum, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in serum, GSH-Px activity in liver, glutathione content in serum and liver, eviscerated yield rate and chest muscle yield, and the relative weight of spleen and liver were linearly and/or quadratically increased (P < 0.05). Moreover, YH enhanced the mRNA levels of nuclear factor erythroid 2-related factor 2, heme oxygennase-1 (HO-1), GSH-Px1 and SOD1 (linear and/or quadratic, P < 0.05).

CONCLUSION

Dietary YH beneficially affected growth performance, serum parameters, organ relative weight, carcass traits, meat quality and antioxidant status in broilers, indicating its potential application as a promising feed additive in broiler production. © 2021 Society of Chemical Industry.

Mycotoxins binder supplementation alleviates aflatoxin B1 toxic effects on the immune response and intestinal barrier function in broilers

This experiment was conducted to evaluate whether a commercial mycotoxins-binder, XL, could effectively attenuate the negative effects of Aflatoxin B₁ (AFB₁) on growth performance, immunological function, and intestinal health in birds. Two hundred forty 1-day-old Arbor Acres broiler chickens were randomly divided into 4 treatments using a 2 × 2 factorial randomized design with 2 levels of dietary mycotoxins binder (0 or 2g /kg) and 2 AFB₁ supplemented levels (0 or 200 μg/kg) from 0 to 42 d. Results showed that AFB₁ exposure impaired growth performance by decreasing BWG in 1–21 d and 1–42 d, decreasing FI in 1–21 d, increasing FCR in 1–21 d and 1–42 d (P < 0.05). Broilers fed AFB₁- contaminated diet impaired the immune function, as evident by decreasing IgA contents, Newcastle disease antibody titers in serum, and sIgA contents of jejunal mucosa at 21 d (P < 0.05). On the other hand, AFB₁ challenge significantly increased the gene expression of proinflammatory factors in spleen at 21 d and liver at 42 d, and significantly decreased claudin-1 expression at 42 d and occludin expression at 21 d, and increased claudin-2 at 21 d in jejunum of broiler chickens (P < 0.05) compared to the basal diet group. Dietary XL supplementation significantly decreased the gene expression of IL-6 in spleen at 21 d and IL-1β in liver at 42 d, cytochrome P450 3A4 (CYP3A4) expression in liver at 21 d of broilers (P < 0.05) compared with the nonsupplemented birds, regardless of AFB₁ challenged or not. Inclusion of 2 g/kg XL increased serum ALB at 42 d, IgM and IgA at 42 d, Newcastle disease antibody titer level at 35 d (P < 0.05). Dietary XL addition enhanced intestinal barrier function by increasing the expression of claudin-1 at 21 d and Occludin at 42 d (P < 0.05) in jejunum. Conclusively, 2 g/kg mycotoxins-binder can relieve the toxic effect of AFB₁ on broilers.

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.

Effects of age on immune function in broiler chickens

BACKGROUND

There are many diseases in poultry, many of which are caused by poor immune function. It is not clear how cytokines and various immune cell functions change with age in modern broilers. The purpose of this study was to explore the patterns of development of the immunity of the broiler chickens in cage.

RESULTS

The results showed that there were 3 development patterns of immunity in the broiler chickens. The first pattern was Down-Up. Cytokines and some immune indicators first decreased and then increased, and the lowest levels of immunity basically occurred from d 6 to 13. The second pattern was Up-Down, and from d 30 to 34, the highest levels of non-specific cellular immunity components, such as the peripheral blood mononuclear macrophage ratio, specific cellular immunity components, such as the peripheral blood helper T (Th) cell ratio and T cell and B cell proliferation activity, and mucosal immunity components, such as the ileal CD4, TGF-β1 and IgA mRNA levels, were observed. The third pattern was Up-Up, and the levels of the non-specific cellular immunity components, such as the serum nitric oxide (NO), C3 and C4 levels, the specific cellular immunity components, such as the spleen index, peripheral blood IL-2, IFN-γ/IL-4, cytotoxic T (Tc) cell ratio, and splenic NF-κB mRNA levels, the humoral immunity components, such as the serum IgG level, the mucosal immunity components, such as the ileal MHC-II, CD3d, TCRβ subunit, TCRζ subunit, IFN-γ, pIgR mRNA and ileal mucosa sIgA levels, were continuing to increase from d 1 to 34.

CONCLUSIONS

It could be concluded that the immune system and its function have not developed well in the broiler chickens d 6 to 13 and that the immune system does not mature until d 30 to 34 in the broiler chickens in cages. It is necessary to enhance the immune function of the broiler chickens through nutritional measures from d 1 to 30.

Protective effect of Polygonatum sibiricum polysaccharide on cyclophosphamide-induced immunosuppression in chickens

The purpose of the study was to evaluate the protective effects of polygonatum sibiricum polysaccharide (PP), an important component of rhizome polygonatum, on cyclophosphamide (CY) induced immunosuppressed chickens. Four hundred and eighty one-day-old Erlang mountainous chickens were randomly allocated into four treatments. The main factors consisted of dietary supplement (PP at 0 or 800 mg/kg of diet) and immunosuppressive challenge (birds challenged with CY or treated with sterile saline). The results showed that PP enhanced chickens' growth performance via elevating daily weight gain (DWG), serum protein production, and decreasing feed conversion ratio (FCR). Moreover, physical measurements revealed that PP accelerated recovery of relative weights of immune organs and maintained their structure and function. Biochemical analysis indicated that PP significantly stimulated immunoglobulin and antioxidant indexes in serum, and improved the proliferation of peripheral blood T lymphocytes. In addition, PP promoted immune organs cells to enter into S and G₂/M phases as well as inhibited the apoptosis in the spleen, thymus, and bursa of Fabricius. PP up regulated the expression of IL-2, IL-6 and IFN-γ genes. Therefore, PP performs a profile in antagonizing Cy-induced immunosuppression in chickens, and it seems that PP can be used as a potential immunostimulant agent.

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.

Effect of Yeast Culture (Saccharomyces cerevisiae) on Broilers: A Preliminary Study on the Effective Components of Yeast Culture

Simple Summary

The value of yeast culture (YC) as alternative feed additives in poultry farming has been proven. YC is a nutrient-rich and complex micro-ecological fermentation product containing various metabolites. However, the major or specific effective components of YC and their importance in poultry farming are unknown. Herein, we screened the “effective ingredients” of YCs obtained from different fermentation times based on metabolomics and animal feeding experiments. Glycine, fructose, inositol, galactose, and sucrose were identified as potential effective metabolites in YCs. These findings provide an important basis for objective, accurate, and quick evaluation of the quality of YC products, as well as a scientific understanding of their functions.

Abstract

This study was aimed at determining the effective ingredients of yeast culture (YC) for animal breeding. First, the contents of YCs obtained from various fermentation times were detected using gas-chromatography. A total of 85 compounds were identified. Next, 336 Arbor Acres (AA) broilers were randomly divided into seven experimental groups and fed a basal diet, diets supplemented with YCs obtained at various fermentation times, or SZ1 (a commercial YC product). A significant increase in body weight gain (BWG) and a significant decrease in feed conversion ratio (FCR) of AA broiler chicks were observed with YC supplementation. Additionally, most of blood and immunological indices were improved with YC supplementation. According to the production performance and the results of multivariate analysis, glycine, fructose, inositol, galactose, and sucrose were found as the potential effective compounds of YC and were involved in metabolic pathways including glycine, serine, and threonine metabolism. Supplementation with diets based on combinations of effective compounds improved weight gain, feed efficiency, serum immunoglobulin A, and immunoglobulin G, but decreased blood urea concentration. These findings suggest YCs as effective and harmless feed additives with improved nutritional properties for broiler chicks.

Effects of dietary Enterococcus faecium NCIMB 11181 supplementation on growth performance and cellular and humoral immune responses in broiler chickens

This study evaluated the effects of dietary Enterococcus faecium NCIMB 11181 on growth performance and immune response in broiler chickens. A total of 360 1-day-old Arbor Acres male birds were randomly assigned to 4 treatments that administered different dosages of E. faecium (0, 5 × 107, 1 × 108, and 2 × 108 CFU E. faecium/kg diet). The results revealed that average daily gain (ADG) changed quadratically, while feed conversion rate (FCR) increased linearly from day 22 to 35 and day 1 to 35 (P < 0.05). Supplementation of E. faecium at 5 × 107CFU/kg diet resulted in increased ADG (P < 0.05) compared with the other groups. Birds fed with 2 × 108 CFU/kg E. faecium exhibited increased peripheral blood lymphocyte proliferation in response to concanavalin A (Con A) (P < 0.05) at day 35 and enhanced skin responses following phytohemagglutinin (PHA) injection (P < 0.05) at 12 h. Serum lysozyme activity at day 21 increased linearly with dietary E. faecium concentration (P < 0.05), the highest activity was observed in the 1 × 108 and the 2 × 108 CFU E. faecium groups (P < 0.01). Serum levels of proinflammatory cytokines IL-1β, IL-2, IL-6, IFN-γ, and anti-inflammatory IL-4, IL-10 changed linearly or quadratically both at the initial and final phases (P < 0.05). In addition, BSA antibody titers were significantly increased following both primary and secondary inoculation when birds were fed with 1 × 108 or 2 × 108 CFU/kg E. faecium (P < 0.05). In comparison with other groups, birds received 5 × 107 CFU E. faecium exhibited the highest levels of serum IgG (P < 0.05) at day 35. Together, our results revealed that broiler diet supplemented with 5 × 107 CFU/kg E. faecium NCIMB 11181 was appropriate in relation to growth performance under normal conditions. Upon administration with higher dosages of E. faecium NCIMB 11181, obvious immune-stimulatory effects were observed following both cell-mediated and humoral immunity.

Effect of yeast-derived products and distillers dried grains with solubles (DDGS) on antibody-mediated immune response and gene expression of pattern recognition receptors and cytokines in broiler chickens immunized with T-cell dependent antigens

This study evaluated the effect of yeast-derived products on innate and antibody mediated immune response in broiler chickens following immunization with sheep red blood cells (SRBC) and bovine serum albumin (BSA). One-day-old male broiler chickens (Ross-308) were randomly assigned to 6 dietary treatments of 9 replicate cages of 5 birds each per treatment. Dietary treatments consisted of a Control diet without antibiotic, and diets containing 11 mg/kg of virginiamycin, 0.25% of yeast cell wall (YCW), 0.2% of a commercial product Maxi-Gen Plus containing processed yeast and nucleotides, 0.05% of nucleotides, or a diet containing 10% of DDGS. On days 21 and 28 post-hatching, 5 birds per treatment were immunized intramuscularly with both SRBC and BSA. One week after each immunization, blood samples were collected. Serum samples were analyzed by hemagglutination test for antibody response to SRBC, and by ELISA for serum IgM and IgG response to BSA. On d 35, 5 birds per treatment were euthanized and the tissue samples from the cecal tonsils were collected to assess the gene expression of toll-like receptors TLR2b, TLR4, and TLR21, monocyte mannose receptor (MMR), and cytokines IL-10, IL-13, IL-4, IL-12p35, and IFN-γ. The results for gene expression analysis demonstrated that the diet supplemented with YCW increased the expression of TLR2b and T-helper type 2 cytokines IL-10, IL-4, and IL-13 relative to the Control; and the expression of TLR4 and IL-13 was upregulated in the nucleotide-containing diet. However, the diets containing antibiotics or Maxi-Gen Plus downregulated the expression of IFN-γ compared to the control. The primary antibody response to SRBC was not affected by diets. However, the diet containing YCW increased the secondary antibody response to SRBC compared to the antibiotic treatment. Neither primary nor secondary IgG and IgM response against BSA were affected by diets. In conclusion, supplementation of the diet with YCW stimulated Th2 cell-mediated immune response indicating the immunomodulatory activities of these products following immunization with non-inflammatory antigens.