Direct enhancement of the phagocytic and bactericidal capability of abdominal macrophage of chicks by beta-1,3-1,6-glucan

Immunopotentiating effect of lentinan on chicks and its inhibitory effect on Marek's disease virus infection

Marek's disease virus (MDV) is a significant tumorigenic virus that causes severe immunosuppression in chickens. Lentinan (LNT) is an immunomodulator containing β-glucans and is widely used in areas such as antiviral, anticancer, and immune regulation. To investigate the immunomodulatory effects of LNT on specific pathogen-free (SPF) chicks and its potential to inhibit MDV infection, we conducted an MDV challenge experiment and observed the immune-enhancing effect of LNT on SPF chicks. The results showed that LNT promoted the growth and development of SPF chicks and induced the upregulation of cytokines such as Mx protein, interferon-γ (INF-γ), tumor necrosis factor-α (TNF-α), and interleukin-2 (IL-2). The specific gravity of CD4+ T-lymphocytes and CD8+ T-lymphocytes and their ratios were also significantly upregulated. Prophylactic use of LNT inhibited MDV replication in lymphocytes, liver, and spleen. It also alleviated MDV-induced weight loss and hepatosplenomegaly in SPF chicks. The present study confirms that LNT can enhance the levels of innate and cellular immunity in SPF chicks and contributes to the inhibition of MDV replication in vivo and mitigation of immune organ damage in chicks due to MDV infection. This provides an adjunctive measure for better control of MDV infection.

Effects of β-glucan on Salmonella enterica serovar Typhimurium swine colonization and microbiota alterations

BACKGROUND

The 2017 Veterinary Feed Directive eliminated the use of medically important antibiotics for growth promotion of food animals; thus, alternative growth promoters are highly desirable by food animal producers to enhance animal health and reduce pathogen colonization, including the human foodborne pathogen Salmonella. β(1-3)(1-6)-D-glucan (β-glucan) is a soluble fiber with prebiotic characteristics; it has been shown to modulate immune and intestinal functions that strengthen swine resistance to health challenges such as bacterial infections when supplemented in the diets of growing pigs. The current study evaluated the effects of a β-glucan product on gut microbial community structure as well as Salmonella shedding and intestinal colonization.

RESULTS

Five-week-old pigs were fed a β-glucan amended diet at 500 g/ton (n = 13) or a non-amended control diet (n = 14) for three weeks, followed by inoculation of the 27 pigs with 1 × 10⁹ colony forming units of Salmonella enterica serovar Typhimurium strain UK1. While remaining on the respective diets, fecal samples collected at 2, 4, 7, and 16 days post-inoculation (dpi) were similar for Salmonella shedding counts between the two diets. At 16 dpi, Salmonella counts were significantly lower in the cecal contents of the β-glucan-fed pigs (P = 0.0339) and a trend towards a reduction was observed in the Peyer's patches region of the ileum (P = 0.0790) compared to the control pigs. Pigs fed β-glucan for three weeks exhibited an increase in members of the Clostridia class in their fecal microbial communities, and after inoculation with Salmonella, several potentially beneficial microorganisms were enriched in the microbiota of β-glucan-fed pigs (Lactobacillus, Ruminococcaceae, Prevotellaceae, Veillonellaceae, Bifidobacterium and Olsenella).

CONCLUSION

Administration of β-glucan altered the swine gut microbiome and reduced Salmonella colonization in the cecal contents.

Effect of 1,3-Beta Glucans Dietary Addition on the Growth, Intestinal Histology, Blood Biochemical Parameters, Immune Response, and Immune Expression of CD3 and CD20 in Broiler Chickens

This experiment evaluated the impact of the dietary addition of 1,3-β-glucans (GLU) on broiler chickens’ growth, intestinal histology, blood biochemical parameters, and immunity. Two hundred three-day-old male broilers (Ross 308) (97.93 ± 0.19 g/chick) were randomly assigned into four treatments with five replicates, each containing ten birds, in a complete randomized design. The four treatments were formulated with 0, 50, 100, and 150 mg 1,3-β-glucans kg−1 in broiler chicken diets. During the study, no significant impacts (p > 0.05) were observed in weight gain and feed conversion ratio (FCR) between treatment groups. Based on the results of total body weight gain and FCR, the optimal level of 1,3-β-glucan is 120 mg Kg−1. The intestinal histomorphology was improved by GLU supplementation, as indicated by increased villi height and villi height to crypt depth ratio (p < 0.01). All levels of supplemental β-1,3 glucan decreased the serum total cholesterol (TC), triglyceride levels, and low-density lipoprotein cholesterol (LDL-C) (p < 0.05). The serum levels of growth hormones (GH), triiodothyronine (T3), and thyroxine (T4) were increased in GLU-supplemented groups (p < 0.05). The serum immune indices (lysozyme activity, interleukin 10 (IL10), complement 3 (C3), and total protein levels) were increased in the GLU-supplemented groups (p < 0.05). Dietary GLU up-regulated the immunoexpression of CD3 (T-cell marker) and CD20 (B-cell marker) in the spleen of birds (p < 0.01). It can be concluded that 1,3-β-glucan can be added to broiler chicken diets for improving the development and integrity of the intestine and enhancing the bird’s immune status. The optimal level for 1,3-β-glucan dietary supplementation was 120 mg Kg−1. Dietary 1,3-β-glucan has a hypolipidemic effect and improves the hormonal profile of birds without affecting their growth rate.

Yeast β-Glucan Altered Intestinal Microbiome and Metabolome in Older Hens

The prebiotics- and probiotics-mediated positive modulation of the gut microbiota composition is considered a useful approach to improve gut health and food safety in chickens. This study explored the effects of yeast β-glucan (YG) supplementation on intestinal microbiome and metabolites profiles as well as mucosal immunity in older hens. A total of 256 43-week-old hens were randomly assigned to two treatments, with 0 and 200 mg/kg of YG. Results revealed YG-induced downregulation of toll-like receptors (TLRs) and cytokine gene expression in the ileum without any effect on the intestinal barrier. 16S rRNA analysis claimed that YG altered α- and β-diversity and enriched the relative abundance of class Bacilli, orders Lactobacillales and Enterobacteriales, families Lactobacillaceae and Enterobacteriaceae, genera Lactobacillus and Escherichia–Shigella, and species uncultured bacterium-Lactobacillus. Significant downregulation of cutin and suberin, wax biosynthesis, atrazine degradation, vitamin B6 metabolism, phosphotransferase system (PTS), steroid degradation, biosynthesis of unsaturated fatty acids, aminobenzoate degradation and quorum sensing and upregulation of ascorbate and aldarate metabolism, C5-branched dibasic acid metabolism, glyoxylate and dicarboxylate metabolism, pentose and glucuronate interconversions, steroid biosynthesis, carotenoid biosynthesis, porphyrin and chlorophyll metabolism, sesquiterpenoid and triterpenoid biosynthesis, lysine degradation, and ubiquinone and other terpenoid-quinone biosyntheses were observed in YG-treated hens, as substantiated by the findings of untargeted metabolomics analysis. Overall, YG manifests prebiotic properties by altering gut microbiome and metabolite profiles and can downregulate the intestinal mucosal immune response of breeder hens.

Review: β-glucans as Effective Antibiotic Alternatives in Poultry

The occurrence of microbial challenges in commercial poultry farming causes significant economic losses. Antibiotics have been used to control diseases involving bacterial infection in poultry. As the incidence of antibiotic resistance turns out to be a serious problem, there is increased pressure on producers to reduce antibiotic use. With the reduced availability of antibiotics, poultry producers are looking for feed additives to stimulate the immune system of the chicken to resist microbial infection. Some β-glucans have been shown to improve gut health, to increase the flow of new immunocytes, increase macrophage function, stimulate phagocytosis, affect intestinal morphology, enhance goblet cell number and mucin-2 production, induce the increased expression of intestinal tight-junctions, and function as effective anti-inflammatory immunomodulators in poultry. As a result, β-glucans may provide a new tool for producers trying to reduce or eliminate the use of antibiotics in fowl diets. The specific activity of each β-glucan subtype still needs to be investigated. Upon knowledge, optimal β-glucan mixtures may be implemented in order to obtain optimal growth performance, exert anti-inflammatory and immunomodulatory activity, and optimized intestinal morphology and histology responses in poultry. This review provides an extensive overview of the current use of β glucans as additives and putative use as antibiotic alternative in poultry.

The Modulating Effect of Dietary Beta-Glucan Supplementation on Expression of Immune Response Genes of Broilers during a Coccidiosis Challenge

Simple Summary

Avian coccidiosis is the leading parasitic disease in the poultry industry and means to control its damages continue to be explored. This study evaluated the feeding effects of a yeast-derived β-glucan on expression of immune response genes in the spleen, thymus, and bursa of commercial broiler chickens during an Eimeria challenge. The study consisted of two dietary treatments (0% or 0.1% β-glucan) each with or without a coccidiosis challenge. There were significant effects from dietary β-glucan, Eimeria challenge, and their interaction for several gene targets in the spleen, thymus, and bursa on days 10 and 14 of age. Based on the current results, supplementation of dietary β-glucan in Eimeria-challenged birds enhanced and modulated the expression of immune response genes during coccidiosis.

Abstract

This study investigated the effects of a yeast-derived β-glucan (Auxoferm YGT) supplementation on mRNA expression of immune response genes in the spleen, thymus, and bursa of broiler chickens during a mixed Eimeria infection. Day (d)-old chicks (n = 1440) were fed diets containing 0% or 0.1% YGT. On d 8 post-hatch, half the replicate pens (n = 8) were challenged with a mixed inoculum of E. acervulina, E. maxima, and E. tenella. On d 10 and d 14 post-hatch, the spleen, thymus, and bursa were collected to evaluate mRNA abundance by quantitative real-time PCR. Data were analyzed using PROC GLIMMIX model (2-way interaction) and differences were established by LS-MEANS with significance reported at p ≤ 0.05. In spleen tissues at d 10, expression of interleukin (IL)-10 and inducible nitric oxide synthase (iNOS) were elevated in both 0.1% YGT-fed challenged and non-challenged birds. In thymus tissues at d 14, expression of IL-10, IL-17F, interferon (IFN)-γ, iNOS, and macrophage migration inhibitory factor (MIF) were elevated in challenged birds fed 0.1% YGT. In bursal tissues at d 10 and d 14, expression of IL-10, IFN-γ, iNOS (d 10 only), and MIF were elevated in 0.1% YGT-fed challenged and non-challenged birds. Dietary β-glucan supplementation to chicken diets modulated their immune response to the Eimeria challenge.

β-glucan administration improves growth performance and gut health in New Zealand White and APRI rabbits with different breed responses

This study investigated the effects of oral administration of β-glucan 1,3 (pharmaceutical grade 10%) on growth performance and carcass traits in two breeds of weanling rabbits adapted to survive in Egypt, New Zealand White (NZW) and Animal Production Research Institute (APRI) rabbits, with special attention to relative mRNA expression of interleukins and antioxidant enzyme genes, biochemical, and histological alterations. Oral administration of β-glucan with doses 0.25 and 0.5 ml per one-liter of drinking water significantly accelerated body weight gain (BWG) in both rabbits’ breeds, reduced total feed consumption (FC), and reduced feed conversion ratio (FCR), especially the 0.5 ml per one-liter dose in both rabbit breeds. There are remarkable differences in all the growth performance traits due to breed effect. The interaction effect between β-glucan and breed significantly improved BWG, FC, and FCR. There were non-significant differences in all carcass traits studied due to oral administration of β-glucan with both doses, except in dressing percentages. The highest of the dressing percentages were observed at doses 0.25 ml per one-liter (51%) and 0.5 ml per one-liter (52%) compared with control (50%). Our findings show significant variations in the final BW, total daily gain, feed consumption, and total feed conversion ratio between NZW and APRI rabbits. Absence of significant differences in the hot carcass weight and dressing percentage between the genetic groups had been reported in this study. Supplementing NZW and APRI rabbits with β-glucan increased blood total protein and globulin. The duodenal villi dimensions, splenic lymphoid diameter, muscular fiber diameter, and muscular glycogen areas were significantly increased by β-glucan administration. Expression of intestinal interleukin-18 (IL-18) in NZW rabbits treated with 0.25 and 0.5 doses of β-glucan was significantly upregulated and enhanced the immune response. β-glucan upregulated the expression of intestinal occludin mRNA particularly at dose 0.5 β-glucan as well as upregulated intestinal superoxide dismutase 1 (SOD1) and glutathione peroxidase 1 (GPx1), which modulates anti-inflammatory and antioxidant properties. In conclusion, oral administration of β-glucan at a dose of 0.25 or 0.5 ml per one-liter drinking water provided beneficial effects in the growth performance and health status of rabbits.

Effects of dietary supplementation with different levels and molecular weights of fungal β-glucan on performances, health and meat quality in broilers

Objective

To investigate the effects of dietary supplementation with different levels and molecular weights of fungal β-glucan on productive performances, health, carcass traits and meat quality in broilers.

Methods

Two hundred and ten of one-day-old chicks with equal sex were assigned to seven experimental groups in 2×4 factorial arrangement. These groups were supplemented with (0, 10, 30 and 60 ppm) of molecular weight 1-3, 1-6 β-glucan (low or high). High molecular weight β-glucan (H: 943 kDa) was obtained from Ophiocordyceps dipterigena BCC 2073, whereas H with -Irradiation treatment was performed to achieve low molecular weight β-glucan (L: 8 kDa).

Results

There was no statistical significance in productive performances, apparent digestibility and interaction between fixed factors along 42 days of experiment (P>0.05). A higher caecal amylase activity was present in the group that received L, while there was a dramatic decrease in H and the control groups, respectively (P<0.05). The increase of supplemental dose increased caecal amylase activity (P<0.05). Immunomodulatory effects from L was revealed by the marked increase of phagocytic activity, relative weight of thymus and bursa of fabricius (P<0.05). Similarly, the additive dose at 30 ppm provided the same results, whereas the only significant difference with supplementation at 60 ppm was an increase in phagocytic activity (P<0.05). Interestingly, villi height of broilers fed L was higher than other groups (P<0.05). The treatments did not influence haematology, blood chemistry, antibody production level against vaccination, carcass traits and meat quality (P>0.05).

Conclusion

The supplementation of L at 30 ppm was suggested to achieve benefits of immune modulation without adverse effects on other parameters.

Effects of beta-1,3-glucan (AletaTM) on vaccination response in broiler chickens

This 42-day study evaluated the effects of dietary supplementation with β-1,3-glucan (Aleta™) on the vaccination response to Newcastle disease virus (NDV), avian infectious bronchitis virus (IBV), and infectious bursal disease (IBD) in a non-challenged environment. This trial included 600 chicks (all vaccinated with IBD at the hatchery) which were assigned to 1 of 3 treatments: vaccination (NDV, IBV), no vaccination, or vaccination combined with feed supplemented with Aleta (100 g/MT of feed). The vaccination with Aleta treatment group showed a trend for improved FCR that was not statistically significant. Control birds that were not vaccinated for IBV had significantly lower IBV titers on day 21 compared to birds that were vaccinated (both with and without Aleta). Surprisingly, there was significant separation among treatment groups for NDV titer levels, especially on day 21, where birds vaccinated and supplemented with Aleta had significantly higher titer levels compared to vaccination alone or no vaccination at all. Critically, only 14% of the birds receiving the vaccine plus Aleta had titer levels below the critical titer threshold for immunity compared to 28% of the birds receiving the vaccine alone and 40% of the unvaccinated birds. This suggests that Aleta supplementation may help to improve the vaccination response by birds, especially for NDV.

β-Glucan successfully stimulated the immune system in different jawed vertebrate species

Several reports have shown the positive effects of β-glucans on the immune. Howeverthese studies have a broad experimental design including β-glucans compounds. Consequently, a study using the same β-glucan molecule, administration route and experimental design is needed to compare the effects of β-glucan across vertebrate species. For this end, during 28 days we fed four different vertebrate species: mice, dogs, piglets and chicks, with two β-glucan molecules (BG01 and BG02). We measured the serum interleukin 2 as an indicator of innate immune response, the neutrophils and monocytes phagocytosis index as a cellular response and antibody formation as an adaptive response. The results clearly showed that the different β-glucan molecules exhibited biologically differently behaviors, but both molecules stimulate the immune system in a similar pattern in these four species. This finding suggests that vertebrates shared similar mechanisms/patterns in recognizing the β-glucans and confirms the benefits of β-glucans across different vertebrate species.

Debaryomyces hansenii CBS 8339 β-glucan enhances immune responses and down-stream gene signaling pathways in goat peripheral blood leukocytes

Debaryomyces hansenii-derived β-glucan has shown immunostimulant effect on aquaculture species and recently on goat peripheral blood leukocytes. Moreover, the marine yeast D. hansenii CBS 8339 has demonstrated to enhance fish immune response. Nonetheless, the associated immune signaling pathways induced by β-glucan from this marine yeast have not been characterized yet. This study described the effects of β-glucan from D. hansenii CBS 8339 against challenge with Escherichia coli and activation of possible mechanisms on goat peripheral blood leukocytes. The proton nuclear magnetic resonance spectra showed that D. hansenii had β-(1,3)(1,6)-glucan. The phagocytic ability enhanced after E. coli challenge, and nitric oxide production increased before and after challenge in leukocytes stimulated with D. hansenii β-glucan. In addition, an early gene expression stimulation was found related to β-glucan recognition by TLR2 and Dectin-1 receptors, intracellular regulation by Syk, TRAF6, MyD88 and transcription factor NFκB, and effector functions of pro-inflammatory cytokine, such as IL-1β and TNF-α. Interestingly, simulation with D. hansenii-derived β-glucan increased leukocyte viability after E. coli challenge. In conclusion, β-glucan from D. hansenii CBS 8339 reduced cytotoxic effects of E. coli and modulated signaling pathways and innate immune response in goat peripheral blood leukocytes.

Integration of genome wide association studies and whole genome sequencing provides novel insights into fat deposition in chicken

Excessive fat deposition is a negative factor for poultry production because it reduces feed efficiency, increases the cost of meat production and is a health concern for consumers. We genotyped 497 birds from a Brazilian F₂ Chicken Resource Population, using a high-density SNP array (600 K), to estimate the genomic heritability of fat deposition related traits and to identify genomic regions and positional candidate genes (PCGs) associated with these traits. Selection signature regions, haplotype blocks and SNP data from a previous whole genome sequencing study in the founders of this chicken F2 population were used to refine the list of PCGs and to identify potential causative SNPs. We obtained high genomic heritabilities (0.43-0.56) and identified 22 unique QTLs for abdominal fat and carcass fat content traits. These QTLs harbored 26 PCGs involved in biological processes such as fat cell differentiation, insulin and triglyceride levels, and lipid biosynthetic process. Three of these 26 PCGs were located within haplotype blocks there were associated with fat traits, five overlapped with selection signature regions, and 12 contained predicted deleterious variants. The identified QTLs, PCGs and potentially causative SNPs provide new insights into the genetic control of fat deposition and can lead to improved accuracy of selection to reduce excessive fat deposition in chickens.

The impact of β-glucans on performance and response of broiler chickens during a coccidiosis challenge

Coccidiosis is a costly parasitic disease to the poultry industry with multiple prevention methods being explored to control its impact. This study evaluated the feeding effects of β-glucans on performance and responses of chickens during a coccidiosis challenge. Cobb 500 male broilers (n = 1280) were assigned to 1 of 8 treatment groups (8 replicate pens; 20 birds/pen) in a 2 × 4 factorial arrangement, including non-infected and Eimeria-infected birds fed for 28 d a control diet, control + BG (150 g/MT Algamune 50), control + BGZn (100 g/MT Algamune 50 Zn), and control + 0.01% Salinomycin (Sal). On d15, birds in the challenge groups received a mixed Eimeria inoculum. Birds and feed were weighed weekly on a per pen basis to evaluate body weight gain (BWG), feed intake (FI), and feed conversion ratios (FCR). Lesion scores were assessed 6 d post infection (d21) on 3 birds per pen. Performance data were subjected to ANOVA and differences were established using the LS-MEANS statement with significance reported at P ≤ 0.05. There were minor differences in lesion scores among the dietary treatments in the infected groups with reduced duodenal and cecal scores in the Sal group compared to the BGZn and BG groups, respectively. The coccidiosis challenge main effect resulted in a significant reduction in 0-28 d BW and FI. Dietary treatment resulted in non-significant effect on BWG, but Sal addition resulted in increased FI. A significant diet X challenge interaction resulted in higher FCR in the Eimeria-challenged birds supplemented with Sal and BGZn in comparison to the other challenged groups, likely due to reduced mortality in the challenged Sal and BGZn groups. Body composition analysis at d28 revealed that the Eimeria challenge reduced both fat and lean tissue contents, where the β-glucans and Sal birds had lower fat percent than control birds.

Decreased testosterone levels after caponization leads to abdominal fat deposition in chickens

BACKGROUND

Caponization results in reduced androgen levels, which leads to abdominal fat accumulation in capons. In this study, we sought to understand the molecular mechanisms behind this fat accumulation.

RESULTS

Abdominal fat (AF) content increased significantly (P < 0.05) and serum and AF testosterone levels decreased significantly (P < 0.05 or P < 0.01) after caponization. In AF tissue, 90 differentially expressed genes related to lipid metabolism were screened by gene expression profiling in caponized and sham-treated chickens. Among these, six representative genes were significantly up-regulated (APOA1, SCD, FABP7, RXRG, and FADS2) or down-regulated (FABP3) (P < 0.05 or P < 0.01) and were strongly associated with the PPAR pathway. In addition, cell junction pathways were also enriched. In vitro, Fat content was significantly lower in cells treated with testosterone compared with control cells (P < 0.01), and mRNA levels of RXRG, FABP7, and FABP3 changed accordingly, confirming the effect of testosterone on fat deposition.

CONCLUSIONS

The results of this study indicate that testosterone reduction likely regulates gene expression through PPAR and cell junction pathways resulting in increased fat accumulation. These results provide increase our understanding of the biological mechanisms by which caponization induces greater fat accumulation.

Salmonella Serovars and Vaccination Effect on the Immune Responses of Male and Female Layers

Salmonella Enteritidis, S. Gallinarum and S. Pullorum are common serovars to infect poultry and cause diseases differently. The antibody production and cellular immune responses of male and female layers were evaluated before and after inoculation. Before inoculation, S. Gallinarum and S. Pullorum could survive and grow in 10% sera from 6-week-old layers, and S. Enteritidis and E. coli were completely eliminated. The weights of the male and female layers were increased the lowest by inoculation with S. Gallinarum, followed by S. Pullorum, and S. Enteritidis. Inoculation with S. Enteritidis, S. Gallinarum and S. Pullorum increased the antibody titer in the males depending on the serovars and maintained same higher antibody level in females. Furthermore, an increased anti-Salmonella IgG titer was associated with bactericidal ability and the level was reduced by serovars and complemente. Despite the vaccination and serovars, the male layers expressed more IgG2a than IgG1, indicating preferential activation of the Th1 pathway. The inoculation number affected the expression level of IFN-γ and IL-12 in the blood not in the secretion of the peripheral blood mononucleated cells (PBMCs) and more inoculations increased the expression of both cytokines. Inoculation increased more reactive oxygen species (ROS) production in polymorphonuclear (PMN) cells, not the PBMCs. ROS production was greater in cells from the males than from the females and greater in the cells treated with S. Enteritidis than S. Gallinarum and S. Pullorum. These three serovars and their vaccinations differed in sera killing and immune responses.

Effect of Dietary Beta-Glucan on the Performance of Broilers and the Quality of Broiler Breast Meat

A total of 400, one day-old commercial broiler chicks were divided into five diet groups (negative control, positive control group with 55 ppm Zn-bacitracin, 15 ppm β-glucan, 30 ppm β-glucan, and 60 ppm β-glucan) and fed for six weeks. Ten broilers were allotted to each of 40 floor pens. Eight floor pens were randomly assigned to one of the 5 diets. Each diet was fed to the broilers for 6 weeks with free access to water and diet. The survival rate, growth rate, feed efficiency, and feed conversion rate of the broilers were calculated. At the end of the feeding trial, the birds were slaughtered, breast muscles deboned, and quality parameters of the breast meat during storage were determined. The high level of dietary β-glucan (60 ppm) showed better feed conversion ratio and survival rate than the negative control. The survival rate of 60 ppm β-glucan-treated group was the same as that of the antibiotic-treated group, which showed the highest survival rate among the treatments. There was no significant difference in carcass yield, water holding capacity, pH, color, and 2-thiobarbituric acid reactive substances values of chicken breast meat among the 5 treatment groups. Supplementation of 60 ppm β-glucan to broiler diet improved the survival rate and feed conversion rate of broilers to the same level as 55 ppm Zn-bacitracin group. The result indicated that use of β-glucan (60 ppm) can be a potential alternative to antibiotics to improve the survival and performance of broilers. However, dietary β-glucan showed no effects on the quality parameters of chicken breast meat.

Yeast β-d-glucans induced antimicrobial peptide expressions against Salmonella infection in broiler chickens

The present study was designed to investigate the effects of yeast β-d-glucans (YG) on gene expression of endogenous β-defensins (AvBDs), cathelicidins (Cath) and liver-expressed antimicrobial peptide-2 (LEAP-2) in broilers challenged with Salmonella enteritidis (SE). 240 day-old Cobb male broilers were randomly assigned to 2×2 factorial arrangements of treatments with two levels of dietary YG (0 or 200mg/kg in diet) and two levels of SE challenge (0 or 1×10(9) SE at 7-9 days of age). The results showed SE infection reduced growth performance,and increased salmonella cecal colonization and internal organs invasion, increased concentration of intestinal specific IgA and serum specific IgG antibody, as compared to uninfected birds. SE challenge differentially regulated AvBDs, Caths and LEAP-2 gene expression in the jejunum and spleen of broiler chickens during the infection period. However, YG supplementation inhibited the growth depression by SE challenge, and further increased level of serum specific IgG and intestinal specific IgA antibody. Higher level of salmonella colonization and internal organs invasion in the SE-infected birds were reduced by YG. SE-induced differentially expression patterns of AMPs genes was inhibited or changed by YG. Results indicated YG enhance chicken's resistance to salmonella infection.

Barley β-glucan in poultry diets

There has been an increased interest in the use of immunomodulators as substitutes for antibiotics in food animal production. Beta-glucans from yeast and fungi may be ideal substitutes because of their positive effects on the avian immune system without adversely affecting poultry performance. Barley β-glucans, however, have not shown this potential due to the adverse effects dietary inclusion of barley has on poultry performance.

β(1-3)(1-6)-D-glucans modulate immune status in pigs: potential importance for efficiency of commercial farming

BACKGROUND

In face of the challenge of the emergent diseases and the current efforts of the governments to create conditions to ban growth-promoting antibiotics and to improve efficiency of the commercial farming, new opportunities are created for natural, highly effective and cost affordable immunomodulators; able to induce and enhance resistance against diseases and to reduce farming-related stress. Supplementation of animal feed with β(1-3)(1-6)-D-glucans has been repeatedly shown to modulate the immune system ant to influence growth characteristics of farmed animals.

MATERIALS AND METHODS

In our study we focused on evaluation of effects of an insoluble, fungi-derived β(1-3)(1-6)-D-glucan as dietary supplement in piglets. We measured the growth, phagocytosis of peripheral blood cells and interleukin 2 (IL-2) and tumor necrosis factor alpha (TNF-α) production after feeding with 15 mg of glucan/kg/day.

CONCLUSIONS

Following supplementation, β(1-3)(1-6)-D-glucan has been shown to stimulate growth, phagocytic activity, and IL-2 production. In addition, it significantly lowered the cortisol and TNF-α levels after lipopolysaccharide (LPS) challenge.

β-1,3/1,6-Glucan alleviated intestinal mucosal barrier impairment of broiler chickens challenged with Salmonella enterica serovar Typhimurium

This study investigated the protective effect of β-1,3/1,6-glucan on gut morphology, intestinal epithelial tight junctions, and bacterial translocation of broiler chickens challenged with Salmonella enterica serovar Typhimurium. Ninety Salmonella-free Arbor Acre male broiler chickens were randomly divided into 3 groups: negative control group (NC), Salmonella Typhimurium-infected positive group (PC), and the Salmonella Typhimurium-infected group with dietary 100 mg/kg of β-1,3/1,6-glucan supplementation (T) to determine the effect of β-1,3/1,6-glucan on intestinal barrier function. Salmonella Typhimurium challenge alone significantly decreased villus height (P < 0.001), villus height/crypt depth ratio (P < 0.05), and the number of goblet cells (P < 0.001) in the jejunum at 14 d postinfection (dpi), but significantly increased the number of intestinal secretory IgA (sIgA)-expressing cells at 14 dpi (P < 0.01) and total sIgA levels in the jejunum at 7 (P < 0.05) and 14 dpi (P < 0.01) compared with the unchallenged birds (NC). Dietary β-1,3/1,6-glucan supplementation not only significantly increased villus height, villus height/crypt depth ratio, and the number of goblet cells (P < 0.01), but also increased the number of sIgA-expressing cells (P < 0.05) and sIgA content in the jejunum at 14 dpi (P < 0.01) in birds challenged with Salmonella Typhimurium in comparison with Salmonella Typhimurium challenge alone. β-1,3/1,6-Glucan addition had significant inhibitory effects (P < 0.05) on cecal Salmonella colonization levels and liver Salmonella invasion of the Salmonella Typhimurium-infected birds compared with the PC group. Intestinal tight junction proteins claudin-1, claudin-4, and occludin mRNA expression in the jejunum at 14 dpi was significantly decreased by Salmonella Typhimurium challenge alone (P < 0.01) compared with that of the NC group, whereas β-1,3/1,6-glucan supplementation significantly increased claudin-1 and occludin mRNA expression (P < 0.01) at 14 dpi in the jejunum of the Salmonella Typhimurium-infected birds in comparison with the PC group. Our results indicate that dietary β-1,3/1,6-glucan can alleviate intestinal mucosal barrier impairment in broiler chickens challenged with Salmonella Typhimurium.

Effects of dietary β-(1,3)(1,6)-D-glucan supplementation on growth performance, intestinal morphology and haemato-immunological profile of mirror carp (Cyprinus carpio L.)

In recent years, aquaculture research has focused on probiotics, prebiotics, and β-glucans, in order to improve health status and growth performance. Information regarding the effects of β-glucan on growth performance and intestinal immunity of mirror carp (Cyprinus carpio L.) is scarce. An experiment was therefore conducted to investigate the effects of a yeast β-glucan preparation (MacroGard(®) ) on growth performance, intestinal morphology and haemato-immunological indices of mirror carp. Carp (initial weight 11.1 ± 0.0 g) were fed highly purified diets supplemented with 0% (control), 0.1%, 1% or 2% MacroGard(®) for 8 weeks. Fish fed diets containing 1% and 2% MacroGard(®) showed significant improvements in weight gain, specific growth rate and feed conversion ratio compared to fish fed both the control and the 0.1% MacroGard(®) containing diet. Histological appraisal of the intestine showed a significantly higher infiltration of leucocytes into the epithelial layer of fish fed diets supplemented with 1% and 2% MacroGard(®) in the anterior intestine compared to fish fed the control and 0.1% MacroGard(®) diet. This effect was not observed in the posterior intestine. There were no significant differences in the intestinal absorptive surface area and number of goblet cells in either intestinal region. At the end of the experiment, the haematological status of the fish was examined. Compared to control fed fish, the haematocrit value was significantly elevated in fish fed the 2% MacroGard(®) diet. Furthermore, the blood monocyte fraction was significantly higher in fish fed the 1% and 2% MacroGard(®) diets. No significant changes were observed in the other blood parameters assessed. The present study shows that high dietary β-glucan inclusion increases growth performance without detrimental effects on the health indicators assessed. Increased intraepithelial leucocytes in the anterior intestine may indicate a localized immune response; no detrimental effects on intestinal morphology were observed.

Laminarin, a soluble beta-glucan, inhibits macrophage phagocytosis of zymosan but has no effect on lipopolysaccharide mediated augmentation of phagocytosis

Phagocytosis is a fundamental aspect of innate resistance against microbes, including fungi. In this study we investigated the significance of beta-glucan on the surfaces of zymosan particles, derived from Saccharomyces cerevisiae, during phagocytosis by RAW 264.7 macrophages. Phagocytosis was assessed in vitro by macrophage exposure to zymosan particles followed by cell staining and light microscopy. Macrophage ingestion of zymosan was dependent on cellular recognition of the particles' beta-glucans since laminarin, a soluble beta-glucan, inhibited phagocytosis in a concentration dependent manner when added to cell cultures. In contrast, the presence of another carbohydrate, mannan, had no effect on zymosan phagocytosis by cells. In addition we showed that LPS and dexamethasone had opposing effects on phagocytosis of zymosan. LPS significantly augmented ingestion while in contrast dexamethasone, like laminarin, suppressed it. The LPS-enhanced ingestion of zymosan was insensitive to the presence of laminarin in cell cultures, however dexamethasone partially ameliorated the effects of LPS on phagocytosis. Our findings confirm beta-glucan as an important ligand identified by macrophages and required for zymosan phagocytosis in naïve cells, but not in cells previously exposed to LPS.

Immune responses to dietary beta-glucan in broiler chicks during an Eimeria challenge

Escalating consumer concerns regarding pathogen resistance have placed the poultry industry under mounting pressure to eliminate the use of chemotherapeutic agents as feed additives. One possible alternative receiving increased attention is the use of immunomodulators such as β-glucan. A study was conducted to investigate the effects of a yeast-derived β-glucan (Auxoferm YGT) on broiler chick performance, lesion scores, and immune-related gene expression during a mixed Eimeria infection. Day-old chicks were fed diets containing 0, 0.02, or 0.1% YGT. On d 8 posthatch, one-half of the replicate pens were challenged with a mixed inoculum of Eimeria acervulina, Eimeria maxima, and Eimeria tenella. Measurements were taken and samples collected on d 4, 10, 14, and 21 posthatch. Dietary supplementation had no effect on performance or mortality. On d 14, 3 birds per pen (n = 24/treatment) were scored for intestinal coccidia lesions. Gross lesion severity was significantly reduced in birds supplemented with 0.1% YGT. On d 10, inducible nitric oxide synthase (iNOS) expression was downregulated in the jejunum of challenged birds fed 0.1% YGT. Expression of iNOS in the ileum was downregulated in the nonchallenged birds, but upregulated in the challenged birds fed 0.1% YGT on d 14. Interleukin (IL)-18 was upregulated in the jejunum of 0.1% YGT-treated birds. Interferon (IFN)-γ expression was decreased in challenged and nonchallenged birds fed 0.1% YGT. The IL-4 expression was downregulated in the nonchallenged birds with 0.1% YGT diet supplementation. The IL-13 and mucin-1 levels were also reduced due to β-glucan supplementation. Mucin-2 expression was increased in the nonchallenged birds, but decreased in the infected birds fed 0.1% YGT. These results suggest that although Auxoferm YGT at doses of 0.02 and 0.1% does not influence performance, it significantly reduces lesion severity and is capable of altering immune-related gene expression profiles, favoring an enhanced T helper type-1 cell response during coccidiosis.

Differential splenic cytokine responses to dietary immune modulation by diverse chicken lines

Nutritional modulation of the immune system is an often exploited but poorly characterized process. In chickens and other food production animals, dietary enhancement of the immune response is an attractive alternative to antimicrobial use. A yeast cell wall component, beta-1,3/1,6-glucan, augments the response to disease in poultry and other species; however, the mechanism of action is not clear. Ascorbic acid and corticosterone are better characterized immunomodulators. In chickens, the spleen acts both as reservoir and activation site for leukocytes and, therefore, splenic gene expression reflects systemic immune function. To determine effects of genetic line and dietary immunomodulators, chickens of outbred broiler and inbred Leghorn and Fayoumi lines were fed either a basal diet or an experimental diet containing beta-glucans, ascorbic acid, or corticosterone from 56 to 77 d of age. Spleens were harvested, mRNA was isolated, and expression of interleukin (IL)-4, IL-6, IL-18, macrophage inflammatory protein-1beta, interferon-gamma, and phosphoinositide 3-kinase p110gamma transcripts was measured by quantitative reverse transcription PCR. Effects of diet, genetic line, sex, and diet x genetic line interaction on weight gain and gene expression were analyzed. At 1, 2, and 3 wk after starting the diet treatments, birds fed the corticosterone diet had gained less weight compared with birds fed the other diets (P < 0.001). Sex affected expression of IL-18 (P = 0.010), with higher levels in males. There was a significant interaction between genetic line and diet on expression of IL-4, IL-6, and IL-18 (P = 0.021, 0.006, and 0.026, respectively). Broiler line gene expression did not change in response to the experimental diet. Splenic expression of IL-6 was higher in Leghorns fed the basal or ascorbic acid diets, rather than the beta-glucan or corticosterone diets, whereas the opposite relationship was observed in the Fayoumi line. Expression of IL-4 and IL-18 responded to diet only within the Fayoumi line. The differential splenic expression of birds from diverse genetic lines in response to nutritional immunomodulation emphasizes the need for further study of this process.

Performance and immune responses to dietary beta-glucan in broiler chicks

During the first week posthatch, the avian immune system is immature and inefficient at protecting chicks from invading pathogens. Among immunomodulators, beta-glucans are known as biological response modifiers due to their ability to activate the immune system. Current research suggests that beta-glucans may enhance avian immunity; however, very little is known about their influence on regulation of immune function. A study was performed to evaluate the effects of dietary beta-glucan on growth performance, immune organ weights, peripheral blood cell profiles, and immune-related gene expression in the intestine. One-day-old chicks were fed a diet containing 0, 0.02, or 0.1% yeast beta-glucan (n = 30/treatment). On d 7 and 14 posthatch, body and relative immune organ weights were measured and small intestinal sections were collected to evaluate gene expression by quantitative real-time PCR. Peripheral blood samples were also collected to determine heterophil:lymphocyte ratios. Supplementation of beta-glucan did not significantly affect BW gains, and no significant differences were observed among groups for relative immune organ weights or heterophil:lymphocyte ratios. Compared with controls, expression of interleukin (IL)-8 was downregulated in the beta-glucan-treated groups on d 7 and 14. On d 14, beta-glucan inclusion resulted in increased inducible nitric oxide synthase expression. Expression of IL-18 was upregulated on d 7 but reduced on d 14 due to beta-glucan supplementation. On d 7, interferon-gamma and IL-4 expression decreased in the beta-glucan-treated groups. However, on d 14, IL-4 expression was upregulated in the supplemented groups. Intestinal expression of IL-13 was also downregulated in the beta-glucan-treated birds on d 7. These results suggest that dietary inclusion of beta-glucans altered the cytokine-chemokine balance; however, it did not elicit a robust immune response in the absence of a challenge, resulting in no deleterious effects on performance.

Bacterial clearance, heterophil function, and hematological parameters of transport-stressed turkey poults supplemented with dietary yeast extract

Yeast extracts (YE) contain biological response modifiers that may be useful as alternatives to antibiotics for controlling pathogens in poultry production and mitigating the deleterious effects of production stressors. The objective of the present study was to determine the ability of a commercial dietary YE (Alphamune) to modulate the immune response in male turkey poults challenged with Escherichia coli and subjected to transport stress. Alphamune was added to turkey poult diets at 0, 500, or 1,000 g/ton. Poults were challenged by air sac injection with 60 cfu of E. coli at 1 wk of age. At 3 wk of age, these challenged birds were subjected to transport stress and birds were bled and necropsied the following morning. Blood cell numbers and percentages, hematological parameters, and clinical chemistry values were determined. Oxidative burst activity of isolated heterophils was measured using stimulation with phorbol myristate acetate and a 2',7'-dichlorofluorescein diacetate assay. Data were analyzed using GLM and least squares means procedures of the SAS program. The numbers and percentages of heterophils in peripheral blood were increased and their oxidative burst activity was stimulated by YE. The stress challenge dramatically increased oxidative burst and this increase was significantly modulated by YE treatment. Serum levels of calcium, phosphorus, and triglycerides were decreased and uric acid levels, erythrocyte numbers, hemoglobin, and hematocrit were increased by YE supplementation. Bacteria were isolated from the air sac and liver of a lower percentage of birds provided with YE. These results suggest that dietary YE has potential as a nonantibiotic alternative for decreasing bacterial pathogens in turkey production.