Feeding strategy and prebiotic supplementation: Effects on immune responses and gut health in the early life stage of broiler chickens

This study aimed to investigate the effects of early or late feeding strategies and prebiotic, on immune responses and gut health during the early life stage of broiler chickens. A total of 240 day-old male broiler chicks were used in a 2 × 3 factorial arrangement of treatments that comprised 2 feeding strategies (early or late) and 3 levels of prebiotic (0, recommended dosage or three times the recommended dosage) in a completely randomized design with 4 pen replicates and 10 broilers per each. Compared to broiler chickens that had early access to feed, delayed access to feed resulted in an increased population of Escherichia coli and a decreased population of Lactobacillus spp. and Bifidobacterium spp. in the ileum (P < 0.05). Additionally, delayed access to feed led to a decrease in villus height, crypt depth, villus height: villus width ratio, goblet cell density, and mucin 2 gene expression in the ileum (P < 0.05). The supplementation of prebiotics in both the late and early feeding strategy groups resulted in increased villus height, crypt depth, goblet cell density, mucin 2 gene expression, and antibodies against Infectious Bursal Disease (IBD). Additionally, it led to an improvement in the foot web thickness index (P < 0.05). Furthermore, it resulted in a significant decrease in the population of Escherichia coli, while the populations of Lactobacillus spp. and Bifidobacterium spp. in the ileum were significantly increased (P < 0.05). Therefore, this study suggests that incorporating prebiotics in the starter diet can effectively enhance immune responses and promote gut health, regardless of the feeding strategy (early or late). In conclusion, this study demonstrates the potential benefits of incorporating prebiotics into poultry diets to alleviate the detrimental effects of delayed access to feed and improve gut health during the early life stage of broiler chickens.

Carvacrol attenuated lipopolysaccharide-induced intestinal injury by down-regulating TLRs gene expression and regulating the gut microbiota in rabbit

Carvacrol (CAR) is a plant extract that has been reported to enhance antioxidant activity in animals. However, the effect of CAR on the intestinal health of rabbits is poorly understood. Here, we investigated whether CAR exerts protective effects on the intestinal health of rabbits following lipopolysaccharide (LPS) challenge and whether these effects were mediated via the reduction of intestinal inflammation and the regulation of the intestinal flora. Intestinal damage was assessed in LPS-challenged rabbits treated or not with CAR. The serum levels of inflammatory factors were assessed by enzyme-linked immunosorbent assay. Histopathological changes in the ileum and cecum were examined using hematoxylin and eosin staining. The relative gene expression levels of inflammatory factors and tight junction proteins in the rabbit cecum were determined by qRT-PCR. High-throughput sequencing analysis of the microbial 16S rRNA gene was performed using the Illumina NovaSeq Platform. The results showed that CAR can prevent intestinal inflammation and damage as well as mitigate gut dysbiosis in rabbits following LPS challenge. Our study provides a theoretical reference for the application of dietary CAR in rabbit production.

The anticoccidial effect of alcoholic extract of Citrullus colocynthis fruit and Juglans regia peel‌ in experimentally infected domestic chicken

One of the main illnesses within the poultry industry is coccidiosis. Anticoccidial medicines applied in the poultry industry show many shortcomings and new control measures are necessary. The current research aimed to study the effect of extract of Citrullus colocynthis and Juglans regia peel on growth performance, gut bacteria, Haematological, Anticoccidial Index (ACI), and Optimum Anticoccidial Activity (OAA) of coccidiosis-infected domestic chicken. The maximum weight gain was observed in the groups treated with 0.001% and 0.01% C. colocynthis extract. Moreover, 0.01% C. colocynthis extract treatment increased two factors of ACI and OAA by 121.42 and 109, respectively, which were higher than commercial anticoccidial (Sulfaclozine). The extract of C. colocynthis fruit and J. regia peel decreased monocytes and eosinophils haematological factors and increased basophils in birds infected with Eimeria. Both extracts modulated intestinal microbiome haematological factors in birds infected with Eimeria, while J. regia peel extract had better performance than C. colocynthis fruit extract. These results indicate that used C. colocynthis and J. regia extracts have an anti-coccidial effect and the potential to control Eimeria infection.

Glycerol monolaurate attenuated immunological stress and intestinal mucosal injury by regulating the gut microbiota and activating AMPK/Nrf2 signaling pathway in lipopolysaccharide-challenged broilers

This study was conducted to investigate the effects of glycerol monolaurate (GML) on lipopolysaccharide (LPS)-induced immunological stress and intestinal mucosal injury in broilers and its underlying mechanisms. A total of 144 one-d-old Arbor Acres broilers were allocated to a 2 × 2 factorial arrangement involving dietary treatment (0 or 1,200 mg/kg dietary GML) and LPS challenge (injected with saline or Escherichia coli LPS on d 16, 18, and 20). Samples were collected on d 21. The results revealed that dietary GML augmented serum immunoglobulin A (P = 0.009) and immunoglobulin G (P < 0.001) levels in challenged birds. Dietary GML normalized LPS-induced variations in serum interleukin-6, interferon-gamma, and LPS levels (P < 0.05), jejunal villus height (P = 0.030), and gene expression of interleukin-6, macrophage inflammatory protein-3 alpha, Toll-like receptor 4, nuclear factor kappa-B, caspase-1, tight junction proteins, adenosine monophosphate-activated protein kinase alpha 1 (AMPKα1), nuclear factor-erythroid 2-related factor 2 (Nrf2), and superoxide dismutase-1 (P < 0.05). GML supplementation ameliorated LPS-induced peroxidation by reducing malondialdehyde content and increasing antioxidant enzyme activity (P < 0.05). Dietary GML enhanced the abundances of Anaerostipes, Pseudoflavonifractor, and Gordonibacter and reduced the proportion of Phascolarctobacterium in challenged birds. Dietary GML was positively correlated with alterations in antioxidant enzyme activities and AMPKα1, Nrf2, and zonula occludens-1 expressions. The genera Anaerostipes, Lachnospira, Gordonibacter, Lachnospira, Marvinbryantia, Peptococcus, and Pseudoflavonifractor were linked to attenuated inflammation and improved antioxidant capacity of challenged birds. In conclusion, dietary GML alleviated LPS-induced immunological stress and intestinal injury of broilers by suppressing inflammation and oxidative stress. Dietary GML regulated cecal microbiota and activated the AMPK/Nrf2 pathway in LPS-challenged broilers.

A Proteolytic Enzyme Treatment to Improve Ulva laetevirens and Solieria chordalis Seaweed Co-Product Digestibility, Performance and Health in Broilers

To explore the potential use of seaweed co-products for broiler diets, this study investigates whether an enzyme treatment of seaweed co-products improves performance, in vivo digestibility and health in broilers. In total, 360 Ross 308 male broilers were fed one of 5 experimental diets: a basal diet, or a basal diet including the U. laetevirens or S. chordalis co-product, with or without proteolytic enzyme treatment of the seaweed, using 6 replicate pens of 12 birds each. The starter (d 0–13) and grower (d 14–21) diet contained 5 and 10% (w/w) seaweed product, respectively. A general linear model with contrast statements was used after model assumptions and goodness of fit were evaluated through normal distribution of residuals. Inclusion of seaweed in the broiler diets increased body weight gain (+14%; P = 0.002), and feed intake (+12%; P = 0.001) in the third week of the experiment. Birds fed the U. laetevirens compared to the S. chordalis diets had a higher body weight gain (+11%; P = 0.007), and a lower feed conversion ratio (FCR; -7%; P < 0.001). Seaweed inclusion reduced apparent pre-cecal digestibility of all nutrients (P < 0.05). Birds fed U. laetevirens vs. S. chordalis diets had a 10% reduced villus length (P < 0.001). Enzymatic treatment reduced the digestibility of most nutrients, and increased crypt depth in birds fed the U. laetevirens diets, whereas the opposite was observed for the birds fed the S. chordalis diets (Seaweed × Enzyme P = 0.035). Untreated vs. treated seaweed in the diets led to lower (−60%) plasma Interleukin-13 levels (P = 0.035). In conclusion, the proteolytic enzyme treatment of the seaweed co-products did not improve performance nor health-related parameters, and reduced digestibility of the diets. Dietary inclusion of U. laetevirens co-products did improve performance based on growth and FCR, whereas inclusion of S. chordalis did not. Inclusion of U. laetevirens in broiler diets slightly reduced duodenal villus length and crypt depth. The inflammation response was strongly reduced, specifically in birds fed the untreated U. laetevirens diet, making the U. laetevirens co-product of interest for future research.

Potential Replacements for Antibiotic Growth Promoters in Poultry: Interactions at the Gut Level and Their Impact on Host Immunity

The chicken gastrointestinal tract (GIT) has a complex, biodiverse microbial community of ~ 9 million bacterial genes plus archaea and fungi that links the host diet to its health. This microbial population contributes to host physiology through metabolite signaling while also providing local and systemic nutrients to multiple organ systems. In a homeostatic state, the host-microbial interaction is symbiotic; however, physiological issues are associated with dysregulated microbiota. Manipulating the microbiota is a therapeutic option, and the concept of adding beneficial bacteria to the intestine has led to probiotic and prebiotic development. The gut microbiome is readily changeable by diet, antibiotics, pathogenic infections, and host- and environmental-dependent events. The intestine performs key roles of nutrient absorption, tolerance of beneficial microbiota, yet responding to undesirable microbes or microbial products and preventing translocation to sterile body compartments. During homeostasis, the immune system is actively preventing or modulating the response to known or innocuous antigens. Manipulating the microbiota through nutrition, modulating host immunity, preventing pathogen colonization, or improving intestinal barrier function has led to novel methods to prevent disease, but also resulted in improved body weight, feed conversion, and carcass yield in poultry. This review highlights the importance of adding different feed additives to the diets of poultry in order to manipulate and enhance health and productivity of flocks.

Glycerol Monolaurate Ameliorated Intestinal Barrier and Immunity in Broilers by Regulating Intestinal Inflammation, Antioxidant Balance, and Intestinal Microbiota

This study was conducted to investigate the impact of glycerol monolaurate (GML) on performance, immunity, intestinal barrier, and cecal microbiota in broiler chicks. A total of 360 one-day-old broilers (Arbor Acres) with an average weight of 45.7 g were randomly allocated to five dietary groups as follows: basal diet and basal diets complemented with 300, 600, 900, or 1200 mg/kg GML. Samples were collected at 7 and 14 days of age. Results revealed that feed intake increased (P < 0.05) after 900 and 1200 mg/kg GML were administered during the entire 14-day experiment period. Dietary GML decreased (P < 0.05) crypt depth and increased the villus height-to-crypt depth ratio of the jejunum. In the serum and jejunum, supplementation with more than 600 mg/kg GML reduced (P < 0.05) interleukin-1β, tumor necrosis factor-α, and malondialdehyde levels and increased (P < 0.05) the levels of immunoglobulin G, jejunal mucin 2, total antioxidant capacity, and total superoxide dismutase. GML down-regulate (P < 0.05) jejunal interleukin-1β and interferon-γ expression and increased (P < 0.05) the mRNA level of zonula occludens 1 and occludin. A reduced (P < 0.05) expression of toll-like receptor 4 and nuclear factor kappa-B was shown in GML-treated groups. In addition, GML modulated the composition of the cecal microbiota of the broilers, improved (P < 0.05) microbial diversity, and increased (P < 0.05) the abundance of butyrate-producing bacteria. Spearman’s correlation analysis revealed that the genera Barnesiella, Coprobacter, Lachnospiraceae, Faecalibacterium, Bacteroides, Odoriacter, and Parabacteroides were related to inflammation and intestinal integrity. In conclusion, GML ameliorated intestinal morphology and barrier function in broiler chicks probably by regulating intestinal immune and antioxidant balance, as well as intestinal microbiota.

Xylanase impact beyond performance: A microbiome approach in laying hens

Anti-nutritional compounds such as non-starch polysaccharides (NSP) are present in viscous cereals used in feed for poultry. Therefore, exogenous carbohydrases are commonly added to monogastric feed to degrade these NSP. Our hypothesis is that xylanase not only improves laying hen performance and digestibility, but also induces a significant shift in microbial composition within the intestinal tract and thereby might exert a prebiotic effect. In this context, a better understanding on whether and how the chicken gut microbial population can be modulated by xylanase is required. To do so, the effects of dietary supplementation of xylanase on performance, apparent total tract digestibility (ATTD) and cecal microbiome in laying hens were evaluated in the present study. A total of 96 HiSex laying hens were used in this experiment (3 diets and 16 replicates of 2 hens). Xylanase was added to the diets at concentrations of 0, 45,000 (15 g/t Xygest^TM HT) and 90,000 U/kg (30 g/t Xygest HT). The diets were based on wheat (~55%), soybean and sunflower meal. The lowest dosage, 45,000 U/kg, significantly increased average egg weight and improved feed efficiency compared to the control treatment (P<0.05). Egg quality parameters were significantly improved in the experiment in response to the xylanase addition. For example, during the last 28 days of the trial, birds receiving the 45,000 U/kg and the 90,000 U/kg treatments exhibited an increase in Haugh units and albumin heights (P<0.05). Compared with the control, the ATTD of organic matter and crude protein were drastically improved in the 45,000 U/kg treatment group (P<0.05). Furthermore, gross energy and the ATTD of crude fat were improved significantly for birds fed 90,000 U/kg group compared to the control. Importantly, 16S rRNA gene analysis revealed that xylanase at 45,000 U/kg dosage can exert a change in the cecal microbiome. A significant increase in beneficial bacteria (Bacilli class; Enterococcaceae and Lactobacillales orders; Merdibacter, Enterococcus and Nocardiopsis genera; Enterococcus casseliflavus species) was documented when adding 45,000 U/kg xylanase to the diet of laying hens. In conclusion, dietary supplementation of xylanase 45,000 U/kg significantly improved laying hen performance and digestibility. Furthermore, microbiome data suggest that xylanase modulates the laying hen bacterial population beneficially, thus potentially exerting a prebiotic effect.

Mandated restrictions on the use of medically important antibiotics in broiler chicken production in Canada: implications, emerging challenges, and opportunities for bolstering gastrointestinal function and health– A review

Chicken Farmers of Canada has been progressively phasing out prophylactic use of antibiotics in broiler chicken production. Consequently, hatcheries, veterinarians, and nutritionists have been mandated to contend with less reliance on use of preventive antibiotics. A topical concern is the increased risk of proliferation of enteric pathogens leading to poor performance, increased mortality and compromised welfare. Moreover, the gut harbors several taxa such as Campylobacter and Salmonella capable of causing significant illnesses in humans via contaminated poultry products. This has created opportunity for research and development of dietary strategies designed to modulate gastrointestinal environment for enhanced performance and food safety. Albeit with inconsistent responses, literature data suggests that dietary strategies such as feed enzymes, probiotics/prebiotics and phytogenic feed additives can bolster gut health and function in broiler chickens. However, much of the efficacy data was generated at controlled research settings that vary significantly with the complex commercial broiler production operations due to variation in dietary, health and environmental conditions. This review will summarize implications of mandated restrictions on the preventative use of antibiotics and emerging Canadian broiler production programs to meet processor specifications. Challenges and opportunities for integrating alternative dietary strategies in commercial broiler production settings will be highlighted.

Cinnamon bark oil and coconut oil emulsions modified small intestinal motility and barrier function in laying hens in an ex vivo experiment

1. Plant extracts and oils are supplemented in diets for chickens due to their antimicrobial capacities; however, little information exists whether they influence intestinal motility and barrier function.2. The present study aimed to determine the effect of increasing levels of cinnamon bark oil (CBO; 0%, 0.038%, 0.076% and 0.151%) and coconut oil emulsions prepared with soy and sunflower lecithin on the contractile function of enteric wall muscles in the jejunum and ileum and jejunal barrier function in laying hens.3. For testing muscle contraction, mid-jejunal and ileal segments (n = 4 each per hen) from four laying hens were placed in a longitudinal orientation into isolated organ baths filled with Krebs buffer and fastened to force transducers. Muscle segments were induced to contract with acetylcholine and the effects of the oil emulsions on contraction were measured.4. For barrier function, distal jejunal pieces were stripped of serosa before mounting into Ussing chambers and recording changes in short-circuit current (I_SC) and transepithelial tissue conductivity (G_T) before and after addition of the respective emulsion.5. The CBO decreased the muscle tone, representing a relaxation of on average 36.2% and 42.6% for the jejunum and ileum, respectively, compared to before the addition (P < 0.001). Moreover, CBO linearly decreased the I_SC and G_T of the jejunal mucosa, indicating a greater absorption of anions and increased barrier function (P < 0.001). Only the coconut oil-sunflower lecithin emulsion relaxed the muscles, whereas both coconut oil-lecithin emulsions increased the I_SC but reduced the G_T of the jejunal mucosa, which suggested an increased cation absorption and decreased paracellular permeability, respectively (P < 0.05).6. In conclusion, CBO and coconut oil-lecithin emulsions showed the potential to increase jejunal barrier function, whereas CBO may be more efficacious to slow down digesta passage in the small intestine.

Water amino acid-chelated trace mineral supplementation decreases circulating and intestinal HSP70 and proinflammatory cytokine gene expression in heat-stressed broiler chickens

Heat stress (HS) is a financial and physiological burden on the poultry industry and the mitigation of the adverse effects of HS is vital to poultry production sustainability. The purpose of this study was, therefore, to determine the effects of an amino acid-chelated trace mineral supplement on growth performance, stress and inflammatory markers, and meat quality in heat-stressed broilers. One day-old Cobb 500 male broilers (n = 480) were allocated into 12 environmental chambers (24 floor pens) and divided into two groups: one group supplemented with amino acid-chelated trace mineral in drinking water and one control group. On day 28, birds were subjected to chronic heat stress (HS, 2 wk, 35 °C and 20% to 30% RH) or maintained at thermoneutral condition (TN, 24 °C) in a 2 × 2 factorial design. Feed intake (FI), water consumption, and body weight were recorded. At day 42, serum fluorescein isothiocyanate dextran (FITC-D) levels, blood gas, electrolyte, and stress markers were measured. Jejunum samples were collected to measure gene expression of stress, inflammation, and tight junction proteins. The rest of the birds were processed to evaluate carcass traits. HS resulted in an increase in core body temperature, which increased water intake and decreased FI, body weight, and feed efficiency (P < 0.05). HS reduced carcass yield and the weight of all parts (P < 0.05). HS significantly increased levels of circulating corticosterone (CORT), heat shock protein 70 (HSP70), interleukin 18 (IL-18), tumor necrosis factor alpha, C-reactive protein, and nucleotide-binding oligomerization domain leucine-rich repeat and pyrin domain-containing 3 expression. HS significantly increased serum FITC-D levels and the expression of HSP70 and IL-18 in the jejunum. Although it did not affect the growth performance, amino acid-chelated trace mineral supplementation reversed the effect of HS by reducing CORT and FITC-D levels and the expression of stress and proinflammatory cytokines in the circulation and the jejunum. However, it upregulated these parameters in birds maintained under TN conditions. Together, these data indicate that the amino acid-chelated trace mineral might alleviate stress and inflammation and improve gut integrity in heat-stressed but not thermoneutral broilers.

The effects of feeding yeast bioactives to broiler breeders and/or their offspring on growth performance, gut development, and immune function in broiler chickens challenged with Eimeria

Yeast bioactives (YB) may stimulate broiler breeders (BB) to increase deposition of immunoglobulins (Ig) in eggs. We investigated the effects of feeding YB (mixture of derivatives from whole yeast subjected to enzymatic hydrolysis) to BB and/or their offspring on growth performance, gut development, and immune function in broiler chickens challenged with Eimeria. The BB (Ross 708 ♀ and Ross ♂) were assigned to 2 groups (60 ♀ and 10 ♂) and fed basal or basal diet supplemented with 500 g of YB/Mt. A total of 250 fertile eggs per treatment were collected, incubated, hatched, and sexed. Additional egg samples were analyzed for IgA and IgY contents. A total of 160 broiler chicks (80 ♀ and 80 ♂) from each breeder experimental group were placed in cages based on sex and BW resulting in 32 cages for each BB treatment group. Cages (16 per BB treatment group) were allocated to basal broiler chick diet or basal diet supplemented with 500 g of YB/Mt. On day 9, half of each BB by broiler chick dietary treatments was challenged with 1 mL of Eimeria culture (100,000 oocysts of Eimeria acervulina and 25,000 oocysts of Eimeria maxima). On day 14, all birds were necropsied for intestinal lesion scores and samples. Feeding YB to BB increased (P < 0.05) IgA concentration in egg yolk. Eimeria challenge decreased (P < 0.05) pancreas weight, jejunal villus height (VH), and growth performance but increased spleen weight, intestinal mass and jejunal mucosa IgA concentration. Independent of Eimeria challenge, feeding YB to BB and/or to chicks resulted in higher (P < 0.001) jejunal VH compared with feeding it to BB only or not at all. In conclusion, Eimeria challenge reduced growth performance and had negative effects on indices of intestinal function and health. Feeding YB to BB increased deposition of IgA in hatching eggs and improved jejunal VH independent of Eimeria challenge when fed to BB and/or to broiler chicks.

Prebiotics and the poultry gastrointestinal tract microbiome

Feed additives that can modulate the poultry gastrointestinal tract and provide benefit to bird performance and health have recently received more interest for commercial applications. Such feed supplements offer an economic advantage because they may directly benefit poultry producers by either decreasing mortality rates of farm animals, increasing bird growth rates, or improve feed efficieny. They can also limit foodborne pathogen establishment in bird flocks by modifying the gastrointestinal microbial population. Prebiotics are known as non-digestible carbohydrates that selectively stimulate the growth of beneficial bacteria, thus improving the overall health of the host. Once prebiotics are introduced to the host, 2 major modes of action can potentially occur. Initially, the corresponding prebiotic reaches the intestine of the chicken without being digested in the upper part of the gastrointestinal tract but are selectively utilized by certain bacteria considered beneficial to the host. Secondly, other gut activities occur due to the presence of the prebiotic, including generation of short-chain fatty acids and lactic acid as microbial fermentation products, a decreased rate of pathogen colonization, and potential bird health benefits. In the current review, the effect of prebiotics on the gastrointestinal tract microbiome will be discussed as well as future directions for further research.

Dietary Factors as Triggers of Low-Grade Chronic Intestinal Inflammation in Poultry

Inflammation is the reaction of the immune system to an injury; it is aimed at the recovery and repair of damaged tissue. The inflammatory response can be beneficial to the animal since it will reestablish tissue homeostasis if well regulated. However, if it is not controlled, inflammation might lead to a chronic response with a subsequent loss of tissue function. The intestine is constantly exposed to a number of environmental triggers that stimulate inflammation and lead to a reduction in performance. The diet and dietary components constitute consistent inflammatory triggers in poultry. Dietary components, such as anti-nutritional compounds, oxidized lipids, mycotoxins, and excess of soluble fiber or protein, are all capable of inducing a low-grade inflammatory response in the intestine of broilers throughout a 5-week grow-out period. We hypothesized that dietary factor-induced chronic intestinal inflammation is a key driver of the lower performance and higher incidence of intestinal problems observed in poultry production. Therefore, this review was aimed at exploring feed-induced chronic inflammation in poultry, the constituents of the diet that might act as inflammatory triggers and the possible effects of chronic intestinal inflammation on the poultry industry.

The Role of Housing Environment and Dietary Protein Source on the Gut Microbiota of Chicken

Simple Summary

The gut microbiota—the community of microorganisms that colonize the gut—is now recognized as a key regulator of immune activity, metabolism, and welfare in all vertebrates, including poultry. The diet and environment can both influence the gut microbiota, but the extent of these changes is unclear in poultry, where diets and environments are important management tools. As the majority of U.S. egg production (>90%) has pledged to move to cage-free egg production by 2025, it is necessary to understand how much the diet and the rearing environment contribute to gut microbiota composition and function, and ultimately to health and production traits of chicken. We addressed this unknown by analyzing the gut microbiota community of laying hens with both the housing environment and diet as variables. We compared conventional cage systems against cage-free systems. In both environments, hens were fed a standard soy-based diet, versus an alternate soy-free diet. We found that cage-free environments generated higher gut microbiota diversity, and that the diet had a relatively lower effect on changing the gut microbiota. Our results highlight the difficulty of promoting consistent, beneficial gut microbiota across production systems or diet variations in commercial poultry conditions.

Abstract

The gut microbiota of chicken has received much attention due to its importance for bird health, food safety, and performance. In the United States, the impending transition to cage-free housing environments has raised many questions about its consequences for poultry health, productivity, and welfare. Therefore, we investigated how housing environments and feed composition affect the poultry gut microbiome. Such data is necessary to inform the design of production systems that promote health and food safety. In this study, we investigated the cecal microbiome of both caged and cage-free laying hens that were fed either an industry-standard soy-based versus a soy-free diet. Caged hens were housed in standard industry-style layer cages with one bird per cage, and cage-free hens were housed in a poultry barn with an outdoor enclosed yard with multiple hens per pen. Our study showed significant differences in the gut microbiota between cage-free and caged environments. Cage free housing generated higher diversity compared to caged housing. Furthermore, we observed a synergistic interaction of soy-based feed in cage-free housing, as the cage-free soy group showed the highest alpha diversity, whereas the caged-soy group showed the lowest diversity overall.

Can dietary zinc diminish the impact of necrotic enteritis on growth performance of broiler chickens by modulating the intestinal immune-system and microbiota?

The objective of this study was to compare the effects of inorganic and proteinate Zn in chickens challenged with coccidia and Clostridium perfringens. A 3 × 2 factorial design was used, with 3 dietary formulations (0 or 90 mg/kg supplemental Zn from ZnSO4 or Zn proteinate, with or without challenge). On day 14, challenged birds were orally gavaged with approx. 5,000 Eimeria maxima sporulated oocysts, and on day 19 to 21 with C. perfringens (108 CFU/D). Productive performance was assessed at day 21 and 28. At 21 D, necrotic enteritis (NE) lesion severity, intestinal permeability, gene expression, and ileal and cecal microbiota were evaluated. An interaction of Zn source by challenge was observed for lesion score and mortality, wherein Zn supplementation decreased the degree of NE lesions (P = 0.02) and mortality due to NE (P = 0.008). In the jejunum, an interaction of Zn source by challenge was observed for the expression of IL-8 (P = 0.001) and INF-γ (P = 0.03), wherein the NE challenge upregulated their expression, but not in the Zn proteinate supplemented birds. Zn proteinate supplementation downregulated iNOS vs. ZnSO4 supplemented birds (P = 0.0003), and supplemental Zn downregulated TLR-2 (P = 0.05) and ZnT5 (P = 0.04), regardless of the source. In the ileal microbiota, Zn proteinate supplementation decreased the frequency of Lactobacillus (P = 0.01), and the challenge increased Enterobacteriaceae (P = 0.01). Dietary Zn decreased NE lesion severity and mortality due to NE; Zn proteinate led to lower expression of IL-8 and INF-γ in challenged birds which may be an indicative of a lessened inflammatory response.

Modulation of the Immune Response to Improve Health and Reduce Foodborne Pathogens in Poultry

Salmonella and Campylobacter are the two leading causes of bacterial-induced foodborne illness in the US. Food production animals including cattle, swine, and chickens are transmission sources for both pathogens. The number of Salmonella outbreaks attributed to poultry has decreased. However, the same cannot be said for Campylobacter where 50⁻70% of human cases result from poultry products. The poultry industry selects heavily on performance traits which adversely affects immune competence. Despite increasing demand for poultry, regulations and public outcry resulted in the ban of antibiotic growth promoters, pressuring the industry to find alternatives to manage flock health. One approach is to incorporate a program that naturally enhances/modulates the bird's immune response. Immunomodulation of the immune system can be achieved using a targeted dietary supplementation and/or feed additive to alter immune function. Science-based modulation of the immune system targets ways to reduce inflammation, boost a weakened response, manage gut health, and provide an alternative approach to prevent disease and control foodborne pathogens when conventional methods are not efficacious or not available. The role of immunomodulation is just one aspect of an integrated, coordinated approach to produce healthy birds that are also safe and wholesome products for consumers.

Inflammation: friend or foe for animal production?

Inflammation is an essential immune response that seeks to contain microbial infection and repair damaged tissue. Increased pro-inflammatory mediators have been associated with enhanced resistance to a range of important poultry and pig pathogens. However, inflammation may also have undesirable consequences, including potentially exacerbating tissue damage and diverting nutrients away from productive purposes. The negative effects of inflammation have led to the active pursuit of anti-inflammatory feed additives and/or strategies. These approaches may, however, impair the ability of an animal to respond appropriately and effectively to the array of pathogens that are likely to be encountered in commercial production, and specifically young animals who may be particularly reliant on innate immune responses. Thus, promoting an animal's capacity to mount a rapid, acute inflammatory response to control and contain the infection and the timely transition to anti-inflammatory, tissue repair processes, and a homeostatic state are suggested as the optimum scenario to maintain an animal's resistance to pathogens and minimize non-productive nutrient losses. Important future studies will help to unravel the trade-offs, and relevant metabolic pathways, between robust immune defense and optimum productive performance, and thus provide real insight into methods to appropriately influence this relationship.

Gut immunity: its development and reasons and opportunities for modulation in monogastric production animals

The intestine performs the critical roles of nutrient acquisition, tolerance of innocuous and beneficial microorganisms, while retaining the ability to respond appropriately to undesirable microbes or microbial products and preventing their translocation to more sterile body compartments. Various components contribute to antimicrobial defenses in the intestine. The mucus layer(s), antimicrobial peptides and IgA provide the first line of defense, and seek to trap and facilitate the removal of invading microbes. If breached, invading microbes next encounter a single layer of epithelial cells and, below this, the lamina propria with its associated immune cells. The gut immune system has developmental stages, and studies from different species demonstrate that innate capability develops earlier than acquired. In addition, various factors may influence the developmental process; for example, the composition and activity of the gut microbiota, antimicrobials, maternally derived antibodies, host genetics, and various stressors (e.g. feed deprivation). Therefore, it is clear that particularly younger (meat-producing) animals are reliant on innate immune responses (as well as passive immunity) for a considerable period of their productive life, and thus focusing on modulating appropriate innate responses should be an intervention priority. The gut microbiota is probably the most influential factor for immune development and capability. Interventions (e.g. probiotics, prebiotics, antibodies, etc.) that appropriately modulate the composition or activity of the intestinal microbiota can play an important role in shaping the desired functionality of the innate (and acquired) response. In addition, innate immune mediators, such as toll-like receptor agonists, cytokines, etc., may provide more specific ways to suitably modulate the response. A better understanding of mucosal immunology, signaling pathways, and processes, etc., will provide even more precise methods in the future to boost innate immune capability and minimize any associated (e.g. nutrient) costs. This will provide the livestock industry with more effective options to promote robust and efficient productivity.