Necrotic enteritis in broilers: an updated review on the pathogenesis

Effect of stimbiotic on growth performance, nutrient digestibility, oocyst shedding, blood profiles, and intestinal microbiota in necrotic enteritis-challenged broiler

This experiment was conducted to investigate the effect of stimbiotic (STB) in broilers with necrotic enteritis (NE). A total of 180 one-day-old Arbor Acres (initial body weight of 34.81 ± 1.04 g) were used in this experiment for 32 days. All broilers were randomly allocated into six treatments, and each experimental group had 10 replicate cages with three broilers per cage. The experiment was conducted in a 2 × 3 factorial design consisting of two levels of challenge (challenge and non-challenge) and three levels of STB (0, 0.05, and 0.1%). The NE challenge significantly decreased (P < 0.05) growth performance, heterophil levels in blood, and intestinal lesion scores compared to the non-challenge group. Supplementation of 0.05% STB significantly decreased (P < 0.05) feed conversion ratio and the number of oocysts per gram of feces compared to the supplementation of 0 and 0.1% STB. At the genus level, the supplementation of 0.05% STB significantly decreased (P < 0.05) the abundance of Enterobacterales compared to the other groups on d 32. In conclusion, supplementation with 0.05% STB in a diet could positively regulate the fecal microflora and alleviate the decline in growth performance and nutrient digestibility caused by NE.

Alternative to antimicrobial growth promoters in the diets of broilers challenged with subclinical necrotic enteritis

Necrotic enteritis (NE) is a disease of worldwide distribution, which affects young broilers and causes economic losses on a scale of 6 billion dollars per year. For decades, NE was controlled in poultry flocks by dietary administration of low doses of antimicrobial growth promoters (AGPs). However, an increase in NE incidence was noted after the AGP ban. This study aimed to compare the effect of an antibiotic (Enramycin) diet to a combination of sodium butyrate, hydrolyzed yeast, and zinc proteinate (ViligenTM) on broiler diets regarding performance, blood parameters, intestinal permeability, morphology and lesions, and carcass yield of broilers challenged with Eimeria spp. and Clostridium perfringens to simulate subclinical necrotic enteritis. A total of 1,150 one-day-old male broiler chickens with an initial average weight of 43.9 ± 0.65 g were allocated to 50 experimental pens. Animals were divided into 5 groups: Negative control (NC) without additives; Positive control (PC) with 0.12 g/ton of Enramycin (8%); V500, V1000, and V1500 with the addition of 500, 1.000, and 1.500 g/ton of Viligen, respectively. All animals were challenged by Eimeria spp. at 7 d of age and by C. perfringens at 17, 18, and 19 d for induction of subclinical NE. The broilers fed with all concentrations of Viligen showed similar performance, blood parameters, intestinal permeability, and carcass yield compared to PC broilers. However, NC broilers showed higher FCR compared to PC broilers from 1 to 33 d (1.42 vs. 1.39) (P = 0.048) and from 1 to 42 d (1.51 vs. 1.49) (P < 0.001). V1500 broilers had fewer intestinal lesions at 28 d when compared to the PC treatment (P < 0.05) and showed that higher Viligen inclusion resulted in lower intestinal damage. At 21 d, the V500 group showed higher intestinal morphology characteristics (VH:VD 4.9 vs. 3.5) compared to the PC treatment (P < 0.001). Thus, in this study, the dietary addition of Viligen to broilers challenged by an experimental model of subclinical NE resulted in lower intestinal damage and similar performance to that obtained by the addition of Enramycin.

The anticoccidial effects of probiotics and prebiotics on the live coccidia vaccine and the subsequent influence on poultry performance post-challenge with mixed Eimeria species

Live vaccines containing Eimeria oocysts are commercially available to protect against avian coccidiosis. Additionally, probiotics (PRO) and prebiotics (PRE) improve the poultry productivity and health and can be used as anticoccidial substitutes. However, the impact of PRO and PRE on reproductive potential, lesion score, intestinal health, and immunization outcomes of the live coccidia vaccines has not received adequate attention. Five groups of unsexed 1-day-old broiler chicks were used as follows: negative control (NC); challenged control (CC); vaccinated and challenged (VC); vaccinated, PRO-treated, and challenged (V-PRO); and vaccinated, PRE-treated, and challenged (V-PRE). At 21 d post-vaccination (pv), the vaccine increased the count of cecal anaerobes (P ≤ 0.05) and coliforms (P > 0.05) as well as harmed body weight gain (WG) (P ≤ 0.05), cecal lactic acid bacteria (P ≤ 0.05), and plasma carotenoid level (P > 0.05). None of the additives decreased oocyst shedding after vaccination, although they lowered the middle intestine and cecal lesion scores (P > 0.05). Compared to VC (2.68 ± 0.12) and V-PRE (2.66 ± 0.05), the V-PRO group showed an improved carotenoid level pv (2.96 ± 0.05) (P ≤ 0.05). V-PRE exhibited higher WG (822.95 ± 18.25) (P > 0.05) and FI (1153.01 ± 10.02) (P ≤ 0.05) than VC (781.86 ± 25.16 and 1109.85 ± 33.68) and V-PRO pv (787.61 ± 19.92 and 1077.43 ± 15.99). Following the homologous coccidia challenge, coccidia-vaccinated broilers adminstered the PRO or PRE continued to exhibit protection levels comparable to those received the vaccine alone. During 2 weeks post-challenge, VC, V-PRO and V-PRE improved bird performance and reduced oocyst shedding and lesion scores compared to CC. Ultimately, PRO and PRE treatments did not significantly reverse the reduction in growth performance in broiler chickens vaccinated against coccidia during the 1st three weeks of age.

Combined Effect of Nigella sativa and Kefir on the Live Performance and Health of Broiler Chickens Affected by Necrotic Enteritis

Coccidiosis and necrotic enteritis (NE) are prevalent poultry ailments worldwide, leading to decreased live performance and elevated mortality rates without antibiotic usage. This study evaluated Nigella sativa (black cumin) seeds (BCS) and kefir as alternatives to antibiotics for broilers. An in vivo study over a 28-day period, using 384 Cobb 500 male broilers organized into six treatment groups as part of a completely randomized block experimental design was conducted. Each treatment group included eight replicates, with each replicate containing eight birds. The treatments included positive control, negative control, antibiotic control, 5% BCS in feed, 20% kefir in drinking water, and a combination of 5% BCS and 20% kefir. NE was induced in broilers by administering ~5000 oocysts of Eimeria maxima orally on day 14, followed by inoculation with about 108 CFU/mL of Clostridium perfringens (Cp) (strain Cp#4) on days 19, 20, and 21. Live performance metrics including feed intake, body weight gain, and feed conversion were assessed in broilers. Additionally, NE disease outcomes such as lesion scores, mortality rates, and Cp populations in cecum were determined during the study. The BCS, kefir, and the combination had no detrimental effect on broiler live performance. BCS-treated and combination groups had lower NE scores (p > 0.05) in comparison to the positive control and exhibited no significant difference (p > 0.05) from antibiotic control. Additionally, treatment groups and antibiotic control were not significantly different (p > 0.05) in mortality, whereas the BCS and kefir combination significantly reduced (p < 0.05) mortality to 14.1% compared to 31.3% for the positive control. C. perfringens vegetative cells significantly decreased (p < 0.05) in treatments with BCS, kefir, and their combination on days 22 and 28 compared to the positive control. On day 22, Cp sores were significantly lower (p < 0.05) for the kefir and combination treatments compared to the positive control. In conclusion, BCS and kefir successfully reduced C. perfringens infection and mortality without any detrimental impact on broiler live performance with the combined treatment being the most effective. These results suggest that BCS and kefir could serve as potential alternatives to antibiotics in managing NE.

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.

Mechanisms of intestinal epithelial cell damage by Clostridiumperfringens

Clostridium perfringens, a Gram-positive bacterium, causes intestinal diseases in humans and livestock through its toxins, related to alpha toxin (CPA), beta toxin (CPB), C. perfringens enterotoxin (CPE), epsilon toxin (ETX), Iota toxin (ITX), and necrotic enteritis B-like toxin (NetB). These toxins disrupt intestinal barrier, leading to various cell death mechanisms such as necrosis, apoptosis, and necroptosis. Additionally, non-toxin factors like adhesins and degradative enzymes contribute to virulence by enhancing colonization and survival of C. perfringens. A vicious cycle of intestinal barrier breach, misregulated cell death, and subsequent inflammation is at the heart of chronic inflammatory and infectious gastrointestinal diseases. Understanding these mechanisms is essential for developing targeted therapies against C. perfringens-associated intestinal diseases.

The Effects of Bacillus amyloliquefaciens SC06 on Behavior and Brain Function in Broilers Infected by Clostridium perfringens

Poultry studies conducted on Clostridium perfringens (CP) mainly focus on the effects of intestinal health and productive performance. Notably, the probiotic Bacillus amyloliquefaciens SC06 (BaSC06) is known to play a role in preventing bacterial infection. However, whether CP could induce the changes in brain function and behaviors and whether BaSC06 could play roles in these parameters is yet to be reported. The aim of this study was to evaluate the effects of BaSC06 on stress-related behaviors and gene expression, as well as the brain morphology and mRNA sequence of the hypothalamus in broiler chickens. A total of 288 one-day-old chicks were randomly divided into four groups: (1) a control group with no treatment administered or infection; (2) birds treated with the BaSC06 group; (3) a CP group; and (4) a BaSC06 plus CP (Ba_CP) group. The results showed that stress and fear-related behaviors were significantly induced by a CP infection and decreased due to the treatment of BaSC06. CP infection caused pathological damage to the pia and cortex of the brain, while BaSC06 showed a protective effect. CP significantly inhibited hypothalamic GABA and promoted HTR1A gene expression, while BaSC06 promoted GABA and decreased HTR1A gene expression. The different genes were nearly found between the comparisons of control vs. Ba group and Ba vs. CP group, while there were a great number of different genes between the comparisons of control vs. Ba_CP as well as CP vs. Ba_CP. Several different gene expression pathways were found that were related to disease, energy metabolism, and nervous system development. Our results will help to promote poultry welfare and health, as well as provide insights into probiotics to replace antibiotics and reduce resistance in the chicken industry.

Ex vivo pharmacokinetic/pharmacodynamic of hexahydrocolupulone against Clostridium perfringens in broiler chickens

The economic impact of necrotizing enteritis (NE) resulting from Clostridium perfringens infection has been significant within the broiler industry. This study primarily investigated the antibacterial efficacy of hexahydrocolupulone against C. perfringens, and its pharmacokinetics within the ileal contents of broiler chickens. Additionally, a dosing regimen was developed based on the pharmacokinetic/pharmacodynamic (PK/PD) model specific to broiler chickens. Results of the study indicated that the minimum inhibitory concentration (MIC) of hexahydrocolupulone against C. perfringens ranged from 2 mg/L to 16 mg/L in MH broth. However, in ileal content, the MIC ranged from 8 mg/L to 64 mg/L. The mutation prevention concentration (MPC) in the culture medium was found to be 128 mg/L. After oral administration of hexahydrocolupulone at a single dosage of 10-40 mg/kg bodyweight, the peak concentration (Cmax), maximum concentration time (Tmax), and area under the concentration-time curve (AUC) in ileal content of broiler chickens were 291.42-3519.50 μg/g, 1-1.5 h, and 478.99-3121.41 μg h/g, respectively. By integrating the in vivo PK and ex vivo PD data, the AUC0-24h/MIC values required for achieving bacteriostatic, bactericidal, and bacterial eradication effects were determined to be 36.79, 52.67, and 62.71 h, respectively. A dosage regimen of 32.9 mg/kg at 24 h intervals for a duration of 3 days would yield therapeutic efficacy in broiler chickens against C. perfringens, provided that the MIC below 4 mg/L.

Effects of phytase supplementation on broilers fed with calcium and phosphorus-reduced diets, challenged with Eimeria maxima and Eimeria acervulina: influence on growth performance, body composition, bone health, and intestinal integrity

An experiment was conducted to evaluate the effects of phytase in calcium (Ca) and available phosphorous (avP)-reduced diet on growth performance, body composition, bone health, and intestinal integrity of broilers challenged with Eimeria maxima and Eimeria acervulina. A total of 672 14-day-old male broilers were allocated to a 2 × 4 factorial arrangement with 6 replicates per treatment and 14 birds per replicate. Two factors were Eimeria challenge and 4 dietary treatments: 1) a positive control (PC; 0.84% Ca and 0.42% avP); 2) a negative control (NC; 0.74% Ca and 0.27% avP); 3) NC + 500 FTU/Kg of phytase (NC + 500PHY); and 4) NC + 1,500 FTU/Kg of phytase (NC + 1500PHY). On d 14, birds in the Eimeria-challenged groups received a solution containing 15,000 sporulated oocysts of E. maxima and 75,000 sporulated oocysts of E. acervulina via oral gavage. At 5 d postinoculation (DPI), the challenged birds showed a higher (P < 0.01) FITC-d level than the unchallenged birds. While the permeability of the NC group did not differ from the PC group, the phytase supplementation groups (NC + 500PHY and NC + 1500PHY) showed lower (P < 0.05) serum FITC-d levels compared to the NC group. Interaction effects (P < 0.05) of Eimeria challenge and dietary treatments on feed intake (FI), mucin-2 (MUC2) gene expression, bone ash concentration, and mineral apposition rate (MAR) were observed. On 0 to 6 and 0 to 9 DPI, Eimeria challenge decreased (P < 0.01) body weight (BW), body weight gain (BWG), FI, bone mineral density (BMD), bone mineral content (BMC), bone area, fat free bone weight (FFBW), bone ash weight, bone ash percentage and bone ash concentration; and it showed a higher FCR (P < 0.01) compared to the unchallenged group. The reduction Ca and avP in the diet (NC) did not exert adverse effects on all parameters in birds, and supplementing phytase at levels of 500 or 1,500 FTU/Kg improved body composition, bone mineralization, and intestinal permeability, with the higher dose of 1,500 FTU/Kg showing more pronounced enhancements. There was an observed increase in FI (P < 0.01) when phytase was supplemented at 1,500 FTU/Kg during 0 to 6 DPI. In conclusion, results from the current study suggest that dietary nutrients, such as Ca and avP, can be moderately reduced with the supplementation of phytase, particularly in birds infected with Eimeria spp., which has the potential to save feed cost without compromising growth performance, bone health, and intestinal integrity of broilers.

Exploring the predictive power of jejunal microbiome composition in clinical and subclinical necrotic enteritis caused by Clostridium perfringens: insights from a broiler chicken model

BACKGROUND

Necrotic enteritis (NE) is a severe intestinal infection that affects both humans and poultry. It is caused by the bacterium Clostridium perfringens (CP), but the precise mechanisms underlying the disease pathogenesis remain elusive. This study aims to develop an NE broiler chicken model, explore the impact of the microbiome on NE pathogenesis, and study the virulence of CP isolates with different toxin gene combinations.

METHODS

This study established an animal disease model for NE in broiler chickens. The methodology encompassed inducing abrupt protein changes and immunosuppression in the first experiment, and in the second, challenging chickens with CP isolates containing various toxin genes. NE was evaluated through gross and histopathological scoring of the jejunum. Subsequently, jejunal contents were collected from these birds for microbiome analysis via 16S rRNA amplicon sequencing, followed by sequence analysis to investigate microbial diversity and abundance, employing different bioinformatic approaches.

RESULTS

Our findings reveal that CP infection, combined with an abrupt increase in dietary protein concentration and/or infection with the immunosuppressive variant infectious bursal disease virus (vIBDV), predisposed birds to NE development. We observed a significant decrease (p < 0.0001) in the abundance of Lactobacillus and Romboutsia genera in the jejunum, accompanied by a notable increase (p < 0.0001) in Clostridium and Escherichia. Jejunal microbial dysbiosis and severe NE lesions were particularly evident in birds infected with CP isolates containing cpa, netB, tpeL, and cpb2 toxin genes, compared to CP isolates with other toxin gene combinations. Notably, birds that did not develop clinical or subclinical NE following CP infection exhibited a significantly higher (p < 0.0001) level of Romboutsia. These findings shed light on the complex interplay between CP infection, the gut microbiome, and NE pathogenesis in broiler chickens.

CONCLUSION

Our study establishes that dysbiosis within the jejunal microbiome serves as a reliable biomarker for detecting subclinical and clinical NE in broiler chicken models. Additionally, we identify the potential of the genera Romboutsia and Lactobacillus as promising candidates for probiotic development, offering effective alternatives to antibiotics in NE prevention and control.

Evaluation of Natural Antimicrobial Substances Blend as a Replacement for Antibiotic Growth Promoters in Broiler Chickens: Enhancing Growth and Managing Intestinal Bacterial Diseases

In recent years, commercial use of antibiotic growth promoter (AGP) has restrictions due to drug resistance against intestinal pathogenic bacteria: Escherichia coli, Salmonella, and Clostridium perfringens. Currently there is no single non-antibiotic treatment approach that is effective against intestinal illnesses in broiler chicken. Hence, present study aimed to analyze efficacy of blend of natural antimicrobial substances (probiotics, prebiotics, organic acids, and essential oils blend named as AGPR) as replacers of AGPs (BMD and CTC) for promoting growth and controlling bacterial diseases in aforementioned three microbes challenged broiler chickens. Effects of treatments (5) and microbes (3) on growth and health performances in experimental birds were analyzed using two factorial ANOVA. Health performance like pathogen loads, morbidity and mortality was considerably reduced by AGPR. Similarly small intestine villi morphometry, nutrition utilization, serum immune response, and carcass yield, was improved significantly by AGPR equivalent to AGPs. Further, growth performance like body weight gain, feed efficiency was also improved by AGPR compared to control but, non-significantly. Among three microbes, E. coli infections had higher morbidity and mortality rates. It was concluded that AGPR blend could be used to improve growth and control the intestinal bacterial infections in broiler chickens as an alternative for AGPs.

Postbiotic as Novel Alternative Agent or Adjuvant for the Common Antibiotic Utilized in the Food Industry

BACKGROUND

Antibiotic resistance is a serious public health problem as it causes previously manageable diseases to become deadly infections that can cause serious disability or even death. Scientists are creating novel approaches and procedures that are essential for the treatment of infections and limiting the improper use of antibiotics in an effort to counter this rising risk.

OBJECTIVES

With a focus on the numerous postbiotic metabolites formed from the beneficial gut microorganisms, their potential antimicrobial actions, and recent associated advancements in the food and medical areas, this review presents an overview of the emerging ways to prevent antibiotic resistance.

RESULTS

Presently, scientific literature confirms that plant-derived antimicrobials, RNA therapy, fecal microbiota transplantation, vaccines, nanoantibiotics, haemofiltration, predatory bacteria, immunotherapeutics, quorum-sensing inhibitors, phage therapies, and probiotics can be considered natural and efficient antibiotic alternative candidates. The investigations on appropriate probiotic strains have led to the characterization of specific metabolic byproducts of probiotics named postbiotics. Based on preclinical and clinical studies, postbiotics with their unique characteristics in terms of clinical (safe origin, without the potential spread of antibiotic resistance genes, unique and multiple antimicrobial action mechanisms), technological (stability and feasibility of largescale production), and economic (low production costs) aspects can be used as a novel alternative agent or adjuvant for the common antibiotics utilized in the production of animal-based foods.

CONCLUSION

Postbiotic constituents may be a new approach for utilization in the pharmaceutical and food sectors for developing therapeutic treatments. Further metabolomics investigations are required to describe novel postbiotics and clinical trials are also required to define the sufficient dose and optimum administration frequency of postbiotics.

Effects of Lactobacillus plantarum HW1 on Growth Performance, Intestinal Immune Response, Barrier Function, and Cecal Microflora of Broilers with Necrotic Enteritis

The purpose of the study was to investigate the effects of Lactobacillus plantarum HW1 on growth performance, intestinal immune response, barrier function, and cecal microflora of broilers with necrotic enteritis. In total, 180 one-day-old male Cobb 500 broilers were randomly allocated into three groups comprising a non-infected control (NC) group, basal diet + necrotic enteritis challenge (NE) group, and basal diet + 4 × 106 CFU/g Lactobacillus plantarum HW1 + necrotic enteritis challenge (HW1) group. Broilers in the NE and HW1 groups were orally given sporulated coccidian oocysts at day 14 and Clostridium perfringens from days 19 to 21. The results showed that the HW1 treatment increased (p < 0.05) the average daily gain of broilers from days 15 to 28 and from days 0 to 28 compared with the NE group. Moreover, the HW1 treatment decreased (p < 0.05) the oocysts per gram of excreta, intestinal lesion scores, ileal interleukin (IL) 1β and tumor necrosis factor α levels, and serum D-lactic acid and diamine oxidase levels, while increasing (p < 0.05) the ileal IL-10 level, thymus index, and protein expressions of ileal occludin and ZO-1. Additionally, the HW1 treatment decreased (p < 0.05) the jejunal and ileal villus height, jejunal villus height/crypt depth value, and cecal harmful bacterial counts (Clostridium perfringens, Salmonella, Escherichia coli, and Staphylococcus aureus), and increased (p < 0.05) the cecal Lactobacillus count. In conclusion, dietary supplementation with 4 × 106 CFU/g Lactobacillus plantarum HW1 could relieve necrotic enteritis infection-induced intestinal injury and improve growth performance in broilers by improving intestinal barrier function and regulating intestinal microbiology.

Molecular and cellular characterization of immunity conferred by lactobacilli against necrotic enteritis in chickens

Necrotic enteritis is an important enteric disease of poultry that can be controlled with in-feed antibiotics. However, with the concerns over antimicrobial resistance, there is an increased interest in the use of alternatives. Probiotics are one of the alternatives that have gained considerable attention due to their antimicrobial and immunomodulatory activities. Therefore, in the present study, we evaluated the effects of two different Lactobacillus species alone or as a cocktail on prevention of necrotic enteritis. Day-old male broiler chickens were divided into five groups and on days 1, 8, 15, and 22, birds in groups 2 and 3 received 1×108 colony forming units (CFU) of L. johnsonii and L. reuteri, respectively. Group 4 received probiotic cocktails containing both bacteria (108 CFU/bird) and the negative and positive control groups did not receive any lactobacilli. Starting on day 23 post-hatch, birds in all groups (except the negative control group) were orally challenged twice per day with 3×108 CFU of a pathogenic C. perfringens strain for 3 days. Tissue and cecal samples were collected before and after challenge to assess gene expression, lymphocyte subsets determination, and microbiome analysis. On day 26 of age, lesion scoring was performed. The results demonstrated that the group that received the lactobacilli cocktail had significantly reduced lesion scores compared to the positive control group. In addition, the expression of interleukin (IL)-12 in the jejunum and CXC motif chemokine ligand 8 (CXCL8), IL-13, and IL-17 in the ileum were downregulated in the group that received the lactobacilli cocktail when compared to the positive control. Treating chickens with the lactobacilli cocktail prior to challenge enhanced the percentage of CD3-CD8+ cells and Bu-1+IgY+ B cells in the ileum and increased the frequency of monocyte/macrophages, CD3-CD8+ cells, Bu-1+IgM+, and Bu-1+IgY+ B cells in the jejunum. Treatment with the lactobacilli cocktail reduced the relative expression of Gamma-Protobacteria and Firmicutes compared to the positive control group. In conclusion, the results presented here suggest that treatment with the lactobacilli cocktail containing L. johnsonii and L. reuteri reduced necrotic enteritis lesions in the small intestine of chickens, possibly through the modulation of immune responses.

The protective effects of Bacillus licheniformis against inflammatory responses and intestinal barrier damage in broilers with necrotic enteritis induced by Clostridium perfringens

BACKGROUND

Bacillus licheniformis is a gram-positive bacterium that has strong environmental adaptability and can improve the growth performance, immunity, and antioxidant function of broilers. The current study aimed to elucidate the protective capability of B. licheniformis against inflammatory responses and intestinal barrier damage in broilers with necrotic enteritis (NE) induced by Clostridium perfringens (CP).

RESULTS

The results showed that B. licheniformis enhanced the final body weight in broilers compared with that of broilers in the CP group after the stress of infection (P < 0.05). Bacillus licheniformis reversed the decreased levels of serum and jejunum mucosa immunoglobulins and anti-inflammatory cytokines, reduced the values of villus height and the ratio of villus height to crypt depth, and mitigated the increased levels of serum d-lactic acid and diamine oxidase in CP-challenged broilers (P < 0.05). Moreover, B. licheniformis modulated the expression levels of genes involved in the TLR4/NF-κB signalling pathway, the NLRP3 inflammasome activation pathway, and the sirt 1/Parkin signalling pathway in CP-challenged broilers. Compared with the CP challenge group, the B. licheniformis-treated group exhibited reduced abundance values of Shuttleworthia and Alistipes and enhanced abundance values of Parabacteroides in the caecal contents (P < 0.05).

CONCLUSION

Bacillus licheniformis improved the final body weight and alleviated the inflammatory response and intestinal barrier function damage in birds with NE induced by CP by maintaining intestinal physiological function, enhancing immunity, regulating inflammatory cytokine secretion, modulating the mitophagy response, and increasing the abundance of beneficial intestinal flora. © 2023 Society of Chemical Industry.

The fecal biomarker ovotransferrin associates with broiler performance under field conditions

Broilers often suffer from subclinical intestinal health problems of ill-defined etiology, which have a negative impact on performance. Macroscopic and microscopic evaluations can be used to monitor intestinal health, but because these are subjective and time-consuming, respectively, objective and easy-to-measure biomarkers are urgently needed. Fecal biomarkers can potentially be used as noninvasive, objective measures to evaluate gut health in broilers. The aim of the current study was to evaluate ovotransferrin (OVT) as a biomarker in fecal/colonic samples derived from broilers from 27 industrial farms by investigating associations between OVT, broiler performance and gut histology parameters. Eight chickens per farm were randomly selected, weighed and euthanized on d 28 of the production round. A duodenal section was collected to measure the intestinal villus structure (villus length, crypt depth) and the inflammatory status of the gut (CD3+ T-lymphocytes area percentage). The coefficient of variation for the OVT (between farms; 83.45%, within farms; 95.13%) was high compared to the villus length (between farms; 10.91%, within farms; 15.48%), crypt depth (between farms; 15.91%, within farms; 14.10%), villus-to-crypt ratio (between farms; 22.08%, within farms; 20.53%), and CD3+ (between farms; 36.38%, within farms; 26.13%). At farm level, colonic OVT was significantly associated with the average slaughter weight (P = 0.005), daily weight gain (P = 0.007) and the European production index (EPI) (P = 0.009). At broiler level, significant associations were found between colonic OVT and the villus length (P = 0.044) and between the colonic OVT and villus-to-crypt ratio (P = 0.050). These results thus show that quantifying OVT in colon can have merit for evaluation of intestinal health in broilers under field conditions.

Evaluation of the Immunoprotective Capacity of Five Vaccine Candidate Proteins against Avian Necrotic Enteritis and Impact on the Caecal Microbiota of Vaccinated Birds

Avian necrotic enteritis is an enteric disease of broiler chickens caused by certain pathogenic strains of Clostridium perfringens in combination with predisposing factors. A vaccine offering complete protection against the disease has not yet been commercialized. In a previous study, we produced five recombinant proteins predicted to be surface-exposed and unique to necrotic enteritis-causing C. perfringens and the immunogenicity of these potential vaccine candidates was assessed in broiler chickens. In the current work, the relative contribution of the antibodies raised by these putative antigens to protect broiler chickens was evaluated using an experimental necrotic enteritis induction model. Additionally, the link between the immune response elicited and the gut microbiota profiles in immunized birds subjected to infection with virulent C. perfringens was studied. The ELISA results showed that the IgY antibody titers in vaccinated birds on days 21 and 33 were significantly higher than those on days 7 and 14 and those in birds receiving the adjuvant alone, while the relative contribution of the specific immunity attributed to these antibodies could not be precisely determined using this experimental necrotic enteritis induction model. In addition, 16S rRNA gene amplicon sequencing showed that immunization of birds with recombinant proteins had a low impact on the chicken caecal microbiota.

A comprehensive review of the applications of bacteriophage-derived endolysins for foodborne bacterial pathogens and food safety: recent advances, challenges, and future perspective

Foodborne diseases are caused by food contaminated by pathogenic bacteria such as Escherichia coli, Salmonella, Staphylococcus aureus, Listeria monocytogenes, Campylobacter, and Clostridium, a critical threat to human health. As a novel antibacterial agent against foodborne pathogens, endolysins are peptidoglycan hydrolases encoded by bacteriophages that lyse bacterial cells by targeting their cell wall, notably in Gram-positive bacteria due to their naturally exposed peptidoglycan layer. These lytic enzymes have gained scientists' interest in recent years due to their selectivity, mode of action, engineering potential, and lack of resistance mechanisms. The use of endolysins for food safety has undergone significant improvements, which are summarized and discussed in this review. Endolysins can remove bacterial biofilms of foodborne pathogens and their cell wall-binding domain can be employed as a tool for quick detection of foodborne pathogens. We explained the applications of endolysin for eliminating pathogenic bacteria in livestock and various food matrices, as well as the limitations and challenges in use as a dietary supplement. We also highlight the novel techniques of the development of engineering endolysin for targeting Gram-negative bacterial pathogens. In conclusion, endolysin is safe and effective against foodborne pathogens and has no adverse effect on human cells and beneficial microbiota. As a result, endolysin could be employed as a functional bio-preservative agent to improve food stability and safety and maintain the natural taste of food quality.

Effect of synbiotic supplementation on production performance and severity of necrotic enteritis in broilers during an experimental necrotic enteritis challenge

To evaluate the efficacy of synbiotic during a necrotic enteritis (NE) infection, a total of 360 day-old chicks were randomly assigned into 4 experimental groups in a 2 × 2 factorial setup: control, challenge, synbiotic (1 g/kg), and challenge + synbiotic, with 6 replicates. NE was induced by gavaging 1 × 104Eimeria maxima oocysts and 1 × 108 CFU/mL of Clostridium perfringens on d 14 (D14) and D19, 20, and 21, respectively. At D35, the NE challenge decreased the BW gain (P < 0.001) and increased feed conversion ratio (P = 0.03), whereas synbiotic supplementation decreased the feed intake (P = 0.04). At D21, NE challenge increased gut permeability (P < 0.001), decreased regulatory T cells (Tregs) in the cecal tonsil (CT) (P = 0.02), increased Tregs in the spleen (P = 0.02), decreased nitric oxide (NO) production in the spleen (P = 0.04) and decreased IL-10 expression in CT (P = 0.02), whereas synbiotic supplementation increased CD4+:CD8+ T cells in the spleen (P < 0.001) and decreased interferon (IFN)-γ expression in the jejunum (P = 0.07), however, synbiotic supplementation during NE challenge decreased mid-gut lesion score (P < 0.001), increased CD4+:CD8+ T cells in CT and decreased IgA production in bile (P < 0.001), compared to the control group. At D28, synbiotic supplementation decreased CD4+:CD8+ T cells in CT (P < 0.001), whereas synbiotic supplementation during NE challenge decreased Tregs in CT (P < 0.001) and increased NO production in the spleen (P = 0.04), compared to the control group. At D35, the NE challenge decreased CD4+:CD8+ T cells in the spleen (P = 0.03), decreased IgA production in bile (P = 0.02), decreased IL-10 expression in CT (P = 0.04), and decreased IL-10 (P = 0.009), IFN-γ (P = 0.03) and inducible nitric oxide synthase (P = 0.02) expression in the jejunum, whereas synbiotic supplementation increased Tregs in the spleen (P = 0.04), compared to control group. Synbiotic supplementation during the NE challenge decreased both IL-1β (P = 0.02) and IFN-γ (P = 0.001) expression in CT, compared to the control group. It can be concluded that synbiotic supplementation increases production performance by decreasing mid-gut lesions and enhancing protective immunity against NE, and efficiency of synbiotic could be improved by blending additional probiotics and prebiotics.

Genome characteristics of the optrA-positive Clostridium perfringens strain QHY-2 carrying a novel plasmid type

Clostridium perfringens is a bacterial species of importance to both public and animal health. The gene optrA is the first gene that confers resistance to the tedizolid, a last-resort antimicrobial agent in human medicine. Herein, we whole-genome sequenced and analyzed one optrA-positive C. perfringens strain QHY-2 from Tibetan sheep in Qinghai province and identified one optrA plasmid pQHY-2. The plasmid shared similar structure with the optrA-positive plasmids p2C45 and p21-D-5b previously identified in C. perfringens, demonstrating the potential horizontal transmission of the optrA plasmids among C. perfringens strains. Annotation of the optrA-positive plasmids showed optrA and erm(A) located on a segment flanked by IS element IS1216E, and fexA, optrA, and erm(A) located on a segment flanked by IS element ISVlu1, which revealed the possible dissemination mechanism. Additionally, a Tn6218-like transposon carrying aac(6')-aph(2″) and erm(B) was also detected on pQHY-2, demonstrating the transposition of Tn6218 and spread of antibiotic resistance among Clostridium bacteria. Molecular analysis indicated the optrA-positive plasmids belonged to a plasmid type distinct from the pCW3-like plasmids, pCP13-like plasmids, or pIP404-like plasmids. Further structure analysis showed they might be formed by inserting segments into plasmid pCPCPI53k-r1_1, which coexist with two pCW3-like plasmids and one pCP13-like plasmid in C. perfringens strain CPI 53k-r1 isolated from a healthy human in Finland. IMPORTANCE Antimicrobial resistance is now a global concern posing threats to food safety and public health. The pCW3-like plasmids can encode several main toxin genes and three antibiotic resistance genes (ARGs), including tetA(P), tetB(P), and erm(B), which used to be considered as the main carrier of ARGs in Clostridium perfringens. In this study, we found the optrA plasmids, which belonged to a novel plasmid type, could also harbor many other ARGs, indicating this type of plasmid might be the potential repository of ARGs in C. perfringens. Additionally, this type of plasmid could coexist with the pCW3-like plasmids and pCP13-like plasmids that encoded toxin genes associated with gastrointestinal diseases, which showed the potential threat to public health.

The effects of protease, xylanase, and xylo-oligosaccharides on growth performance, nutrient utilization, short-chain fatty acids, and microbiota in Eimeria-challenged broiler chickens fed low-protein diet

A total of 392 Cobb 500 off-sex male broiler chicks were used in a 21-day experiment to study the effect of protease, xylanase, and xylo-oligosaccharides (XOS) on improving growth performance, nutrient utilization (ileal digestibility and total tract retention), gene expression of nutrient transporters, cecal short-chain fatty acids (SCFAs), and microbiota profile of broilers challenged with Eimeria spp. Chicks at 0-day old were allocated to 8 treatments in a 4 × 2 factorial arrangement: 1) corn-soybean meal diet with no enzyme (Con); 2) Con plus 0.2 g/kg protease alone (PRO); 3) Con plus 0.2 g/kg protease combined with 0.1 g/kg xylanase (PRO + XYL); or 4) Con plus 0.5 g/kg xylo-oligosaccharides (XOS); with or without Eimeria challenge. The 4 diets were formulated to be marginally low in crude protein (183 g/kg). Challenged groups were inoculated with a solution containing E. maxima, E. acervulina, and E. tenella oocysts on d 15. Eimeria depressed (P < 0.01) growth performance and nutrient utilization. Supplemental protease improved (P < 0.05) body weight gain and feed intake in the prechallenge phase (d 0-15) but had no effect during the infection period (d 15-21). There was no interaction between infection and feed supplementation for nutrient utilization. The supplementations of either PRO or XOS alone increased (P < 0.01) total tract retention of Ca and tended (P < 0.1) to improve total tract retention of N, P, AME, and AMEn. Eimeria decreased (P < 0.05) expressions of GLUT2, GLUT5, PepT1, ATP2B1, CaSR, Calbidin D28K, NPT2, and ZnT1 but increased (P < 0.01) expression of GLUT1. XOS supplementation increased (P < 0.05) ATP2B1 expression. Protease decreased (P < 0.05) isobutyrate concentration in unchallenged treatments but not in challenged treatments. Eimeria decreased (P < 0.01) cecal saccharolytic SCFAs acetate and propionate but increased (P < 0.01) branched-chain fatty acid isovalerate. The supplementation of PRO + XYL or XOS increased (P < 0.05) cecal butyrate or decreased cecal isobutyrate concentrations, respectively. PRO + XYL and XOS decreased cecal protein levels in unchallenged birds but not challenged ones. Eimeria challenge significantly (P < 0.05) decreased the microbial richness (Observed features) and diversity (Shannon index and phylogenetic diversity) and changed the microbial composition by reducing the abundance of certain bacteria, such as Ruminococcus torques, and increasing the abundance of others, such as Anaerostipes. In contrast, none of the additives had any significant effect on the cecal microbial composition. In conclusion, PRO or XOS supplementation individually improved nutrient utilization. All the additives decreased the cecal content of branched-chain fatty acids, consistent with decreased cecal N concentration, although the effects were more pronounced in unchallenged birds. In addition, none of the feed additives impacted the Eimeria-induced microbial perturbation.

Inclusion of Quillaja Saponin Clarity Q Manages Growth Performance, Immune Response, and Nutrient Transport of Broilers during Subclinical Necrotic Enteritis

Necrotic enteritis (NE) is an intestinal disease that results in poor performance, inefficient nutrient absorption, and has a devastating economic impact on poultry production. This study evaluated the effects of a saponin-based product (Clarity Q, CQ) during an NE challenge. A total of 1200 male chicks were randomly assigned to four dietary treatments (10 pens/treatment; 30 birds/pen): treatment 1 (NC), a non-medicated corn-soybean basal diet; treatment 2 (PC), NC + 50 g/metric ton (MT) of bacitracin methylene disalicylate (BMD); and treatments 3 (CQ15) and 4 (CQ30), NC + 15 and 30 g/MT, respectively. On the day (d) of placement, birds were challenged by a coccidia vaccine to induce NE. On d 8, 14, 28, and 42, performance parameters were measured. On d 8, three birds/pen were necropsied for NE lesions. On d 8 and d 14, jejunum samples from one bird/pen were collected for mRNA abundance of tight junction proteins and nutrient transporter genes. Data were analyzed in JMP (JMP Pro, 16), and significance (p ≤ 0.05) between treatments was identified by Fisher's least significant difference (LSD) test. Compared to PC and NC, CQ15 had higher average daily gain (ADG), while CQ30 had lower average daily feed intake (ADFI) and feed conversion ratio (FCR). NE lesions in the duodenum were lower in CQ15 compared to all other treatments. On d 8, mRNA abundance of CLDN1, CLDN5, AMPK, PepT2, GLUT2, and EAAT3 were significantly greater in CQ30 (p < 0.05) compared to both PC and NC. On d 14, mRNA abundance of ZO2 and PepT2 was significantly lower in PC when compared to all treatments, while that of ANXA1, JAM3, and GLUT5 was comparable to CQ15. In summary, adding Clarity Q to broiler diets has the potential to alleviate adverse effects caused by this enteric disease by improving performance, reducing intestinal lesions, and positively modulating the mRNA abundance of various tight junction proteins and key nutrient transporters during peak NE infection.

Recent Trends on Mitigative Effect of Probiotics on Oxidative-Stress-Induced Gut Dysfunction in Broilers under Necrotic Enteritis Challenge: A Review

Gut health includes normal intestinal physiology, complete intestinal epithelial barrier, efficient immune response, sustained inflammatory balance, healthy microbiota, high nutrient absorption efficiency, nutrient metabolism, and energy balance. One of the diseases that causes severe economic losses to farmers is necrotic enteritis, which occurs primarily in the gut and is associated with high mortality rate. Necrotic enteritis (NE) primarily damages the intestinal mucosa, thereby inducing intestinal inflammation and high immune response which diverts nutrients and energy needed for growth to response mediated effects. In the era of antibiotic ban, dietary interventions like microbial therapy (probiotics) to reduce inflammation, paracellular permeability, and promote gut homeostasis may be the best way to reduce broiler production losses. The current review highlights the severity effects of NE; intestinal inflammation, gut lesions, alteration of gut microbiota balance, cell apoptosis, reduced growth performance, and death. These negative effects are consequences of; disrupted intestinal barrier function and villi development, altered expression of tight junction proteins and protein structure, increased translocation of endotoxins and excessive stimulation of proinflammatory cytokines. We further explored the mechanisms by which probiotics mitigate NE challenge and restore the gut integrity of birds under disease stress; synthesis of metabolites and bacteriocins, competitive exclusion of pathogens, upregulation of tight junction proteins and adhesion molecules, increased secretion of intestinal secretory immunoglobulins and enzymes, reduction in pro-inflammatory cytokines and immune response and the increased production of anti-inflammatory cytokines and immune boost via the modulation of the TLR/NF-ĸ pathway. Furthermore, increased beneficial microbes in the gut microbiome improve nutrient utilization, host immunity, and energy metabolism. Probiotics along with biosecurity measures could mitigate the adverse effects of NE in broiler production.

Mucosal and systemic lymphoid immune responses against Clostridium perfringens strains with variable virulence in the production of necrotic enteritis in broiler chickens

Necrotic enteritis (NE), caused by Clostridium perfringens, is an economically important disease of chickens. Although NE pathogenesis is moderately well studied, the host immune responses against C. perfringens are poorly understood. The present study used an experimental NE model to characterize lymphoid immune responses in the caecal tonsils (CT), bursa of Fabricius, Harderian gland (HG) and spleen tissues of broiler chickens infected with four netB+ C. perfringens strains (CP1, CP5, CP18, and CP26), of which CP18 and CP26 strains also carried the tpeL gene. The gross and histopathological lesions in chickens revealed CP5 to be avirulent, while CP1, CP18, and CP26 strains were virulent with CP26 being "very virulent". Gene expression analysis showed that, while the virulent strains induced a significantly upregulated expression of pro-inflammatory IL-1β gene in CT, the CP26-infected birds had significantly higher CT transcription of IFNγ and IL-6 pro-inflammatory genes compared to CP5-infected or uninfected chickens. Furthermore, CP26 infection also led to significantly increased bursal and HG expression of the anti-inflammatory/regulatory genes, IL-10 or TGFβ, compared to control, CP5 and CP1 groups. Additionally, the splenic pro- and anti-inflammatory transcriptional changes were observed only in the CP26-infected chickens. An antibody-mediated response, as characterized by increased IL-4 and/or IL-13 transcription and elevated IgM levels in birds infected with virulent strains, particularly in the CP26-infected group compared to uninfected controls, was also evident. Collectively, our findings suggest that lymphoid immune responses during NE in chickens are spatially regulated such that the inflammatory responses against C. perfringens depend on the virulence of the strain.

Bacillus subtilis DSM29784 attenuates Clostridium perfringens-induced intestinal damage of broilers by modulating intestinal microbiota and the metabolome

Necrotic enteritis (NE), especially subclinical NE (SNE), without clinical symptoms, in chicks has become one of the most threatening problems to the poultry industry. Therefore, increasing attention has been focused on the research and application of effective probiotic strains as an alternative to antibiotics to prevent SNE in broilers. In the present study, we evaluated the effects of Bacillus subtilis DSM29784 (BS) on the prevention of subclinical necrotic enteritis (SNE) in broilers. A total of 480 1-day-old broiler chickens were randomly assigned to four dietary treatments, each with six replicates pens of twenty birds for 63 d. The negative (Ctr group) and positive (SNE group) groups were only fed a basal diet, while the two treatment groups received basal diets supplemented with BS (1 × 109 colony-forming units BS/kg) (BS group) and 10mg/kg enramycin (ER group), respectively. On days 15, birds except those in the Ctr group were challenged with 20-fold dose coccidiosis vaccine, and then with 1 ml of C. perfringens (2 × 108) at days 18 to 21 for SNE induction. BS, similar to ER, effectively attenuated CP-induced poor growth performance. Moreover, BS pretreatment increased villi height, claudin-1 expression, maltase activity, and immunoglobulin abundance, while decreasing lesional scores, as well as mucosal IFN-γ and TNF-α concentrations. In addition, BS pretreatment increased the relative abundance of beneficial bacteria and decreased that of pathogenic species; many lipid metabolites were enriched in the cecum of treated chickens. These results suggest that BS potentially provides active ingredients that may serve as an antibiotic substitute, effectively preventing SNE-induced growth decline by enhancing intestinal health in broilers.

Dietary 1,3-β-Glucans Affect Growth, Breast Muscle Composition, Antioxidant Activity, Inflammatory Response, and Economic Efficiency in Broiler Chickens

Recently, researchers have been intensively looking for novel, safe antibiotic alternatives because of the prevalence of many clinical and subclinical diseases affecting bird flocks and the risks of using antibiotics in subtherapeutic doses as feed additives. The present study intended to evaluate the potential use of 1,3-β-glucans (GLC) as antibiotic alternative growth promotors and assessed the effect of their dietary inclusion on the growth performance, carcass traits, chemical composition of breast muscles, economic efficiency, blood biochemical parameters, liver histopathology, antioxidant activity, and the proinflammatory response of broiler chickens. This study used 200 three-day-old ROSS broiler chickens (50 chicks/group, 10 chicks/replicate, with an average body weight of 98.71 ± 0.17 g/chick). They were assigned to four experimental groups with four dietary levels of GLC, namely 0, 50, 100, and 150 mg kg−1, for a 35-day feeding period. Birds fed diets containing GLC showed an identical different growth rate to the control group. However, the total feed intake (TFI) increased quadratically in the GLC50 and GLC100 groups as compared to that in the control group. GLC addition had no significant effect on the weights of internal and immune organs, except for a decrease in bursal weight in the GLC150 group (p = 0.01). Dietary GLC addition increased the feed cost and total cost at 50 and 100 mg kg−1 doses. The percentages of n-3 and n-6 PUFA in the breast muscle of broiler chickens fed GLC-supplemented diets increased linearly in a dose-dependent manner (p < 0.01). The serum alanine aminotransferase (ALT) level and the uric acid level were quadratically increased in the GLC150 group. The serum levels of total antioxidant capacity, catalase, superoxide dismutase, interleukin-1β, and interferon-gamma linearly increased, while the MDA level decreased in the GLC-fed groups in a dose-dependent manner. Normal histological characterization of different liver structures in the different groups with moderate round cells was noted as a natural immune response around the hepatic portal area. The different experimental groups showed an average percentage of positive immunostaining to the proinflammatory marker transforming growth factor-beta with an increase in the dose of GLC addition. The results suggest that GLC up to 100 mg kg−1 concentration can be used as a feed additive in the diets of broiler chickens and shows no adverse effects on their growth, dressing percentage, and internal organs. GLC addition in diets improves the antioxidant activity and immune response in birds. GLC help enrich the breast muscle with n-3 and n-6 polyunsaturated fatty acids.

Efficacy of Antibiotic and Non-antibiotic Interventions in Preventing and Treating Necrotic Enteritis in Broiler Chickens: A Systematic Review

The objective of this systematic review was to compare the efficacy of antibiotic and non-antibiotic alternatives in the prevention and treatment of necrotic enteritis (NE) in broiler chickens. In vivo experimental and observational studies that compared the administration of non-antibiotic compounds with antibiotics to prevent or treat NE in broiler chickens and that evaluated mortality and/or clinical or subclinical NE outcome measures were eligible. Four electronic databases were searched in December 2019 and updated in October 2021. Retrieved studies were evaluated in two phases: abstract and design screening. Data were then extracted from included studies. Risk of bias was assessed by outcome following the Cochrane Risk of Bias 2.0 tool. A meta-analysis was not conducted due to heterogeneity across interventions and outcomes. The non-antibiotic and antibiotic groups were compared at the outcome level for individual studies using the mean difference and 95% confidence interval (CI) calculated post hoc from raw data. In total, 1282 studies were originally identified, and 40 were included in the final review. The overall risk of bias for the 89 outcomes was either "high" (n = 34) or "some concerns" (n = 55). Individual study comparisons showed a beneficial trend toward the antibiotic group for reduced mortality, NE lesion scores (overall, jejunum, and ileum), Clostridium perfringens counts, and for most histologic measurements (duodenum, jejunum, and ileum villi height, and jejunum and ileum crypt depth). The non-antibiotic groups showed a beneficial trend for NE duodenum lesion scores and duodenum crypt depth measurements. Based on this review, there is a trend that mostly favors antibiotic compounds in preventing and/or treating NE, but the evidence also suggests no difference when comparing them with non-antibiotic alternatives. Studies assessing this research question were heterogeneous in their intervention conditions and outcomes measured, and there were key aspects of the experimental design not reported in some of the studies.

Citric Acid and Magnolol Ameliorate Clostridium perfringens Challenge in Broiler Chickens

Clostridium perfringens (C. perfringens) is a common pathogenic bacterium implicated in the enteric diseases of animals. Each year, the disease is responsible for billions of dollars of losses worldwide. The development of new phytomedicines as alternatives to antibiotics is becoming a new hotspot for treating such diseases. Citric acid (CA) and magnolol (MA) have been shown to have antibacterial, antioxidant, and growth-promoting properties. Here, the bacteriostatic effects of combinations of CA and MA against C. perfringens were investigated, together with their effects on yellow-hair chickens challenged with C. perfringens. It was found that the optimal CA:MA ratio was 50:3, with a dose of 265 μg/mL significantly inhibiting C. perfringens growth, and 530 μg/mL causing significant damage to the bacterial cell morphology. In animal experiments, C. perfringens challenge reduced the growth, damaged the intestinal structure, activated inflammatory signaling, impaired antioxidant capacity, and perturbed the intestinal flora. These effects were alleviated by combined CA-MA treatment. The CA-MA combination was found to inhibit the TLR/Myd88/NF-κB and Nrf-2/HO-1 signaling pathways. In conclusion, the results suggest the potential of combined CA-MA treatment in alleviating C. perfringens challenge by inhibiting the growth of C. perfringens and affecting the TLR/MyD88/NF-κB and Nrf-2/HO-1 signaling pathways.

A Broad-Spectrum Phage Endolysin (LysCP28) Able to Remove Biofilms and Inactivate Clostridium perfringens Strains

Clostridium perfringens is a gram-positive, anaerobic, spore-forming bacterium capable of producing four major toxins which cause disease symptoms and pathogenesis in humans and animals. C. perfringens strains carrying enterotoxins can cause food poisoning in humans and are associated with meat consumption. An endolysin, named LysCP28, is encoded by orf28 from C. perfringens bacteriophage BG3P. This protein has an N-terminal glycosyl-hydrolase domain (lysozyme) and a C-terminal SH3 domain. Purified LysCP28 (38.8 kDa) exhibited a broad spectrum of lytic activity against C. perfringens strains (77 of 96 or 80.21%), including A, B, C, and D types, isolated from different sources. Moreover, LysCP28 (10 μg/mL) showed high antimicrobial activity and was able to lyse 2 × 10⁷ CFU/mL C. perfringens ATCC 13124 and C. perfringens J21 (animal origin) within 2 h. Necessary due to this pathogenic bacterium's ability to form biofilms, LysCP28 (18.7 μg/mL) was successfully evaluated as an antibiofilm agent in both biofilm removal and formation inhibition. Finally, to confirm the efficacy of LysCP28 in a food matrix, duck meat was contaminated with C. perfringens and treated with endolysin (100 µg/mL and 50 µg/mL), which reduced viable bacteria by 3.2 and 3.08 units-log, respectively, in 48 h at 4 °C. Overall, the endolysin LysCP28 could potentially be used as a biopreservative to reduce C. perfringens contamination during food processing.

Cannabidiol and Nano-Selenium Increase Microvascularization and Reduce Degenerative Changes in Superficial Breast Muscle in C. perfringens-Infected Chickens

Here, we demonstrated the potential of Cannabis-derived cannabidiol (CBD) and nanosized selenium (nano-Se) for the modulation of microvascularization and muscle fiber lesions in superficial breast muscle in C. perfringens-challenged chickens. The administration of CBD resulted in a decreased number of atrophic fibers (3.13 vs. 1.13/1.5 mm²) compared with the control, whereas nano-Se or both substances resulted in a decreased split fiber number (4.13 vs. 1.55/1.5 mm²) and in a lower number of necrotic myofibers (2.38 vs. 0.69/1.5 mm²) in breast muscle than the positive control. There was a significantly higher number of capillary vessels in chickens in the CBD+Nano-Se group than in the control and positive control groups (1.31 vs. 0.97 and 0.98, respectively). Feeding birds experimental diets lowered the activity of DNA damage repair enzymes, including 3,N4-ethenodeoxycytosine (by 39.6%), 1,N6-ethenodeoxyadenosine (by 37.5%), 8-oxo-guanine (by 36.2%), formamidopyrimidine (fapy)-DNA glycosylase (by 56.2%) and human alkyl adenine DNA glycosylase (by 40.2%) in the ileal mucosa, but it did not compromise the blood mitochondrial oxygen consumption rate (-2.67 OD/min on average). These findings indicate a potential link between gut mucosa condition and histopathological changes in superficial pectoral muscle under induced inflammation and show the ameliorative effect of CBD and nano-Se in this cross-talk due to their protection from mucosal DNA damage.

Spray-dried porcine plasma enhances feed efficiency, intestinal integrity, and immune response of broilers challenged with necrotic enteritis

Re-emergence of enteric diseases in the postantibiotic era has imposed severe loss to the poultry industry leading to the urgent need for appropriate additives to maintain gut health. Recently, more attention has been paid to animal plasma due to its high concentrations of active components such as albumins and globulins. The objective of this study was to evaluate the effects of spray-dried porcine plasma (SDP) supplementation during the starter phase (d 0-10) on growth performance, intestine health, and immune response of broilers under necrotic enteritis (NE) challenge. A total of 720 day-old male broiler parental line chicks (Ross 308) were randomly assigned to a 2 (NE challenge: no, yes) × 2 (SDP: 0, 2%) factorial arrangement with 12 replications of 15 chicks each. To induce NE, birds were inoculated with live Eimeria vaccine on d 9 and Clostridium perfringens on d 14. The body weight of birds and feed consumption were measured per pen on d 8, 10, 24, and 29 to calculate performance parameters. On d 16, three birds per pen were sampled to analyse the intestinal lesion score, gut permeability, villi morphology, relative weight of organs, and immune response. Results showed that SDP improved (P < 0.001) FCR in the pre-challenge phase (d 0-8). The results indicated that supplementing SDP lowered (P < 0.01) FCR at the end of the experiment (d 29). Dietary SDP decreased (P < 0.05) the concentration of FITC-d in serum samples of challenged broilers, although it did not affect the intestinal morphology and lesion score. Birds fed with SDP had a higher (P < 0.05) relative weight of bursa (g/kg live body weight) compared to non-supplemented birds. Supplementing SDP reduced the concentration of interleukin-6 (P < 0.05) and α-1 acid glycoprotein (P = 0.051) in serum samples of broilers. In conclusion, supplementation of SDP in the starter phase enhanced feed efficiency and gut integrity in NE challenged broilers, possibly through manipulating the immune response, while further studies targeting intestinal microflora and key genes are required to explore the mode of action.

Production systems and important antimicrobial resistant-pathogenic bacteria in poultry: a review

Economic losses and market constraints caused by bacterial diseases such as colibacillosis due to avian pathogenic Escherichia coli and necrotic enteritis due to Clostridium perfringens remain major problems for poultry producers, despite substantial efforts in prevention and control. Antibiotics have been used not only for the treatment and prevention of such diseases, but also for growth promotion. Consequently, these practices have been linked to the selection and spread of antimicrobial resistant bacteria which constitute a significant global threat to humans, animals, and the environment. To break down the antimicrobial resistance (AMR), poultry producers are restricting the antimicrobial use (AMU) while adopting the antibiotic-free (ABF) and organic production practices to satisfy consumers' demands. However, it is not well understood how ABF and organic poultry production practices influence AMR profiles in the poultry gut microbiome. Various Gram-negative (Salmonella enterica serovars, Campylobacter jejuni/coli, E. coli) and Gram-positive (Enterococcus spp., Staphylococcus spp. and C. perfringens) bacteria harboring multiple AMR determinants have been reported in poultry including organically- and ABF-raised chickens. In this review, we discussed major poultry production systems (conventional, ABF and organic) and their impacts on AMR in some potential pathogenic Gram-negative and Gram-positive bacteria which could allow identifying issues and opportunities to develop efficient and safe production practices in controlling pathogens.

Characterization and evaluation of Colombian propolis on the intestinal integrity of broilers

Nutritional additives such as propolis seek to improve intestinal health as an alternative to the global ban on in-feed antibiotics used as growth promoters (AGP). The objective of this study was to evaluate the effect of propolis supplementation in diet of broilers. Four hundred and fifty straight-run Ross 308 AP broilers were fed with a basal diet (BD) throughout the whole experimental period. Birds were randomly distributed into 5 groups at d 14: negative control without antibiotics nor propolis (AGP-), positive control 500 ppm of Zinc Bacitracin as growth promoter (AGP+), and 3 groups supplemented with 150, 300, and 450 ppm of propolis. Every group included 6 replicates of 15 birds each. Propolis concentration was increased from d 22 to 42, in experimental groups to 300, 600, and 900 ppm of propolis, and 10% of raw soybean was included as a challenge in all groups during the same period. Analysis of productive parameters, intestinal morphometry, and relative quantification of genes associated with epithelial integrity by qPCR were performed at 21 and 42 d. The groups with the greatest weights were those that consumed diets including 150 (21 d) and 900 ppm (42 d) of propolis compared with all treatments. The lowest score of ISI was found at 300 (21 d) and 600 ppm (42 d). A lower degree of injury in digestive system was seen with the inclusion of 300 ppm (21 d) and 900 ppm (42 d). Up-regulation of zonula occludens-1 (ZO-1) was observed in jejunum of broilers supplemented with 150 and 300 ppm at 21 d. Up-regulation of ZO-1 and TGF-β was also evidenced in ileum at all propolis inclusion levels at 42-day-old compared to AGP+ and AGP-. The beneficial effects were evidenced at inclusion levels of 150 ppm in the starter and 900 ppm in the finisher. According to the results, the Colombian propolis inclusion can improve productive performance, physiological parameters, and gene expression associated with intestinal integrity.

Effects of challenge with Clostridium perfringens, Eimeria and both on ileal microbiota of yellow feather broilers

In the poultry industry worldwide, Clostridium perfringens has been causing major economic loss as it can cause necrotic enteritis (NE). The coccidial infection has been considered as the most important predisposing factor of NE caused by C. perfringens. In this study, we aimed to advance our knowledge on ileal microbiota of yellow feather broilers under C. perfringens and/or Eimeria challenge. Total of 80 healthy day old yellow feather broilers were randomly assigned to four groups including: Control, C. perfringens challenge group (C. Per), Eimeria challenge group (Cocc), and C. perfringens plus Eimeria challenge group (Comb). On day 14, the Cocc and Comb group broilers were orally gavaged 1 ml PBS solution containing 25,000 oocysts of Eimeria brunetti and 25,000 oocysts of Eimeria maxima. Starting on day 17, the C. Per and Comb group broilers were orally gavaged 10 mL of C. perfringens per bird (4 × 107 CFU/mL, ATCC® 13124™ Strain) every day for 6 days. 16S rRNA gene sequencing was performed on extracted DNA of ileal digesta samples. The results showed that C. perfringens alone did not affect the alpha diversity of ileal microbiome in yellow feather broilers but co-infection with Eimeria significantly decreased the diversity of ileal microbiota. C. perfringens and Eimeria challenge also decreased the relative abundance of beneficial bacteria including Bacteroidetes at the phylum level and Faecalibacterium at the genus level. At the species level, the relative abundance of Candidatus Arthromitus was significantly decreased in the Eimeria challenged groups. This microbial shift information of ileal microbiota under C. Perfringens and Eimeria challenge provide important reference data for the development of therapeutic approaches to necrotic enteritis in yellow-feather broiler chickens.

Comparative efficacy of tannin-free grain sorghum varieties for the control of necrotic enteritis caused by Clostridium perfringens in broiler chickens

A 28-day battery cage study was conducted to test the efficacy of tannin-free grain sorghum varieties fed to Cobb 500 male broiler chickens (n = 512) and challenged with Eimeria maxima (EM) and Clostridium perfringens (CP). Birds were fed 1 of 8 treatments (corn, red/bronze, white/tan, or U.S. No. 2 sorghum) and were grouped by challenge method (challenged with EM/CP or unchallenged). On d 14, birds in the challenge group were orally inoculated with ∼5,000 oocysts of EM, and on d 19, 20, and 21, birds were given a broth culture of CP with ∼10⁸ CFU/mL once daily. On d 21, three birds were scored for the degree/presence of necrotic enteritis (NE) lesions. Birds and feed were group weighed (d 0, 14, 21, and 28) to calculate average feed intake (FI), body weight gain (BWG), and adjusted feed conversion ratio (AdjFCR). Intestinal integrity was assessed through histological analysis of intestinal tissues, and change in transcriptome was determined using mRNA-sequencing on intestinal mucosa. Relative concentrations of secondary metabolites in grain sorghum were determined by LC-MS/MS analysis. Data were analyzed as a 2-way ANOVA with factors of treatment, challenge and their interaction. Regardless of challenge from 14 to 21 d, birds on the corn, white/tan, and U.S. No. 2 treatments were more efficient than those fed red/bronze treatment (P = 0.0026). From 14 to 28 d, BWG was significantly higher for the white/tan treatment (P = 0.024) compared to the red/bronze treatment. At 21 d, a significant interaction was observed for lesion score (P = 0.0001) in which, challenged birds fed red/bronze and white/tan treatments had reduced intestinal lesions compared to U.S. No. 2 and corn treatments. No differences among treatments were observed in jejunum morphology, but differential expression analysis showed an upregulation in defense response to bacteria and biotic stress in the challenged red/bronze treatment compared to the challenged corn. This study demonstrated improved gut health and minimal impact on growth and efficiency of broilers fed select grain sorghum varieties when challenged with EM/CP.

Antimicrobial monoglycerides for swine and poultry applications

The development of natural, broadly acting antimicrobial solutions to combat viral and bacterial pathogens is a high priority for the livestock industry. Herein, we cover the latest progress in utilizing lipid-based monoglycerides as feed additives to address some of the biggest challenges in animal agriculture. The current industry needs for effective antimicrobial strategies are introduced before discussing why medium-chain monoglycerides are a promising solution due to attractive molecular features and biological functions. We then critically analyze recent application examples in which case monoglycerides demonstrated superior activity to prevent feed transmission of viruses in swine and to mitigate bacterial infections in poultry along with gut microbiome modulation capabilities. Future innovation strategies are also suggested to expand the range of application possibilities and to enable new monoglyceride delivery options.

Necrotic Enteritis in Broiler Chickens: A Review on the Pathogen, Pathogenesis, and Prevention

Clostridium perfringens type A and C are the primary etiological agents associated with necrotic enteritis (NE) in poultry. The predisposing factors implicated in the incidence of NE changes the physical properties of the gut, immunological status of birds, and disrupt the gut microbial homeostasis, causing an over-proliferation of C. perfringens. The principal virulence factors contributing to the pathogenesis of NE are the α-toxin, β-toxin, and NetB toxin. The immune response to NE in poultry is mediated by the Th1 pathway or cytotoxic T-lymphocytes. C. perfringens type A and C are also pathogenic in humans, and hence are of public health significance. C. perfringens intoxications are the third most common bacterial foodborne disease after Salmonella and Campylobacter. The restrictions on the use of antibiotics led to an increased incidence of NE in poultry. Hence, it is essential to develop alternative strategies to keep the prevalence of NE under check. The control strategies rely principally on the positive modulation of host immune response, nutritional manipulation, and pathogen reduction. Current knowledge on the etiology, pathogenesis, predisposing factors, immune response, effect on the gut microbial homeostasis, and preventative strategies of NE in this post-antibiotic era is addressed in this review.

Supplemental Enzyme and Probiotics on the Growth Performance and Nutrient Digestibility of Broilers Fed with a Newly Harvested Corn Diet

A new grain phenomenon happens in newly harvested corn because of its high content of anti-nutritional factors (ANFs), which can cause low nutrient digestibility and diarrhea in animals. Enzymes and probiotics have been shown to relieve the negative effect of ANFs for animals. The purpose of this study was to investigate the effect of enzymes and probiotics on the performance and nutrient digestibility of broilers, fed with newly harvested corn diets. A total of 624 Arbor Acres Plus male broiler chickens were randomly divided into eight treatment groups (A: normal corn diet, CT: newly harvested corn diet, DE: newly harvested corn diet + glucoamylase, PT: newly harvested corn diet + protease, XL: newly harvested corn diet + xylanase, BCC: newly harvested corn diet + Pediococcus acidilactici BCC-1, DE + PT: newly harvested corn diet + glucoamylase + protease, XL + BCC: newly harvested corn diet + xylanase + Pediococcus acidilactici BCC-1). Each group was divided into six replicates, with 13 birds each. On day 21, growth performance, nutrient digestibility, and digestive enzyme activity were measured. Compared with the normal corn diet (PC), the newly harvested corn diet (NC) produced shorter digesta emptying time (p = 0.015) and increased visual fecal water content (p = 0.002) of broilers, however, there was no effect on performance. Compared to the newly harvested corn diet (NC), supplemental enzyme of DE increased the activity of chymotrypsin (p = 0.016), however, no differences in the digestibility of three kinds of organic matter, digesta emptying time, visual fecal water content, or performance were found. Supplemental protease (PT) significantly increased digesta emptying time (p = 0.004) and decreased the activity of maltase (p = 0.007). However, it had no effect on the digestibility of three kinds of organic matter or the performance of broilers. Supplemental xylanase (XL) decreased the activity of amylase (p = 0.006) and maltase (p < 0.001); however, it had no effect on digesta emptying time, visual fecal water content, the digestibility of three kinds of organic matter, or performance of broilers. Supplemental DE, combined with PT (DE + PT), increased the digesta emptying time (p = 0.016) while decreasing the visual fecal water content (p = 0.011), and the activity of amylase (p = 0.011), lipase (p = 0.021), and maltase (p < 0.001), however, there was no effect on performance. Supplemental BCC individually decreased the activity of amylase (p = 0.024) and maltase (p < 0.001), however, it increased the activity of trypsin (p < 0.001) and tended to improve feed conversion ratio (FCR) (p = 0.081). Supplemental BCC-1, combined with XL (XL + BCC), increased the activity of trypsin (p = 0.001) but decreased the activity of amylase (p = 0.013), lipase (p = 0.019), and maltase (p < 0.001). Pediococcus acidilactici BCC-1 (109 cfu/kg), protease (800,000 U/g) individually, or protease (800,000 U/g) in combination with glucoamylase (800,000 U/g) were supplemented in newly harvested corn diets for growing broilers. Hence, this study mainly explores the alleviation effect of enzyme and probiotics on the negative phenomenon caused by the utilization of newly harvested corn in broilers and provides a better solution for the utilization of newly harvested corn in production practice.

Does supplementing β-mannanase modulate the feed-induced immune response and gastrointestinal ecology in poultry and pigs? An appraisal

The provision of adequate and balanced nutrients is critical for efficient and profitable animal protein production. However, non-nutritive components in feedstuffs can elicit responses that can negatively impact nutrient utilization efficiency. For example, dietary β-mannans are recognizable by cell surface mannose receptors are pivotal for diverse cellular functions. This review will evaluate the physiological implications of dietary native β-mannans, the utility of supplemental feed β-mannanase in hydrolyzing β-mannans, and subsequent metabolic responses. Dietary native β-mannans have been implicated in inadvertent stimulation of immune response through a phenomenon called the feed-induced immune response (FIIR), that has been associated with intestinal inflammation and depression in animal performance. Supplemental β-mannanase blunted the FIIR by hydrolyzing native β-mannans to smaller fragments with a reduced ability to stimulate the innate immune system as indicated by the modulation of oxidative stress, mucosal permeability, and blood concentration of acute phase proteins and immunoglobulins in broilers and piglet models. Moreover, β-mannanase hydrolysis of native β-mannans to mannooligosaccharides (MOS) impacted gastrointestinal microbial ecology. Indeed, β-mannanase-derived MOS reduced the concentration of pathogenic bacteria such as Escherichia coli and Salmonella and increased the production of short-chain fatty acids in gastrointestinal tracts of various animal models. Consequently, by hydrolyzing native β-mannans, supplemental β-mannanase may have nutritional, metabolic, and microbial ecology benefits. In summary, integrating multi-functional feed additives such as β-mannanase into feeding programs for monogastric animals will be critical for efficient and sustainable animal protein production in the context of evolving challenges such as the mandated elimination of use of antibiotics for growth promotion.

A mixture of organic acids and thymol protects primary chicken intestinal epithelial cells from Clostridium perfringens infection in vitro

Necrotic enteritis causes economic losses estimated to be up to 6 billion US dollars per year. Clinical and subclinical infections in poultry are also both correlated with decreased growth and feed efficiency. Moreover, in a context of increased antibiotic resistance, feed additives with enhanced antimicrobial properties are a useful and increasingly needed strategy. In this study, the protective effects of a blend of thymol and organic acids against the effects of Clostridium perfringens type A (CP) on chicken intestinal epithelial cells were investigated and compared to bacitracin, a widely used antibiotic in poultry production. Primary chicken intestinal epithelial cells were challenged with CP for a total time of 3 h to assess the beneficial effect of 2 doses of citric acid, dodecanoic acid, and thymol-containing blend, and compare them with bacitracin. During the challenge, different parameters were recorded, such as transepithelial electrical resistance, cell viability, mRNA expression, and reactive oxygen species production. CP induced inflammation with cytokine production and loss of epithelial barrier integrity. It was also able to induce reactive oxygen species production and increase the caspase expression leading to cellular death. The high dose of the blend acted similarly to bacitracin, preventing the disruptive effects of CP and inducing also an increase in zonula occludens-1 mRNA expression. The low dose only partially prevented the disruptive effects of CP but successfully reduced the associated inflammation. This study shows that the usage of thymol combined with 2 organic acids can protect primary chicken intestinal epithelial cells from CP-induced damages creating a valid candidate to substitute or adjuvate the antibiotic treatment against necrotic enteritis.

Therapeutic effect of heat-killed Lactobacillus plantarum L-137 on the gut health and growth of broilers

Although some studies on the effects of para-probiotics on the immune system and intestinal health have been conducted independently of research on antibiotics ass growth promoters. This study investigated the effects of heat-killed Lactobacillus plantarumL-137 (L-137) and antibiotics as preventive and/or therapeutic substances for broilers against subclinical necrotic enteritis caused by Clostridium perfringens (CP). In total, 300 1-day-old broilers (46.13 ± 1.38 g) were randomly stocked at 10 birds pen^-1 in five replicates and divided into six groups, namely T1 and T2, positive and negative control of CP challenge; T3 and T4, prevention with basal diet plus 10 and 50 mg/kg L-137; T5 and T6, prevention and treatment with basal diet plus 50 mg/kg of L-137 and bacitracin at 50 ppm, respectively. Broilers administered L-137 in T4, T5 and bacitracin in T6 showed an improved (p < 0.05) villus height/crypt depth ratio than control groups, suggesting that it might significantly boost growth performance. In contrast to bacitracin, a high dosage of L-137 significantly increased (p < 0.05) the spleen index value and the cytokine levels, as well as the expression of intestinal β-defensin genes on day 28. During the 42-day production period, broilers in T4 and T5 showed a significantly enhanced (p < 0.05) expression of cytokines, AvBD-1 and AvBD-7 on day 42 compared to the control and bacitracin groups. In particular, broilers given the L-137 diets demonstrated no cumulative mortality following CP exposure, compared to a 2% mortality in T6. Our findings provide insight into eco-friendly alternatives to antibiotics for maximizing growth performance, feed efficiency and long-term disease protection in chickens; however, this has to be proven in larger-scale commercial experiments.

Comparative efficacy of postbiotic, probiotic, and antibiotic against necrotic enteritis in broiler chickens

Prevention of necrotic enteritis (NE), caused by Clostridium perfringens (C. perfringens), is one of the most important goals to improve the profitability of broiler chickens. This work aimed to compare the efficacy of 2 antibiotic alternatives including a postbiotic (dry feed additive and aqueous nonviable Lactobacillus (L.) species fermentation) and a probiotic (dry feed additive and aqueous Bacillus (B.) subtilis and B. lischeniformis mixture) with an antibiotic (amoxicillin in water) against NE. Four hundred, day-old broiler chicks were divided into 8 equal groups (Gs), n = 50 each (5 replicates; 10 each). Chickens of G1 (postbiotic dry-feed additive), G2 (postbiotic and antibiotic in drinking water), G3 (postbiotic dry and aqueous), G4 (probiotic dry-feed additive), G5 (probiotic and antibiotic in drinking water), G6 (probiotic dry and aqueous), and G7 (nontreated) were orally inoculated with a toxigenic C. perfringens type A on the d 19 to 21 of age and predisposed with 3X coccidial vaccine for induction of NE. However, chickens of G8 were kept nontreated or challenged. The severity of NE signs was markedly decreased in G3 in comparison with other challenged treatment groups, and the mortality rates were 22%, 10%, 16%, 22%, 12%, 20%, and 36% in Gs 1, 2, 3, 4, 5, 6, and 7, respectively. The best significant (P ≤ 0.05) feed conversion ratio was detected in G3 (1.51), G6 (1.54), and G2 and G8 (1.61). In addition, the European production efficiency factor was significantly (P ≤ 0.05) improved in G3 (279.33) and G2 (266.67), but it was decreased in G7 (177.33) when compared with G8 (339.33). An improvement in intestinal and hepatic pathology and liver function tests, as well as a significant (P ≤ 0.05) decrease in bacterial counts were observed in Gs 2, 5, 3, 6, 1, and 4, respectively in comparison with G7. Immunologically, the highest significant (P ≤ 0.05) hemagglutination inhibition antibody titers for Newcastle disease virus vaccine were in Gs 1 and 3 (6.4 log2). In conclusion, the combined feed and water postbiotic treatment demonstrated promising results in ameliorating the severity of NE and improving the hepatic and the immune status of broiler chickens when compared with the commonly used probiotic and antibiotic.

Increased arginine, lysine, and methionine levels can improve the performance, gut integrity and immune status of turkeys but the effect is interactive and depends on challenge conditions

Arginine (Arg), lysine (Lys), and methionine (Met) can be used to support the health status of turkeys. The present study investigated selected performance, gut integrity, and immunological parameters in turkeys reared in optimal or challenge conditions. The experiment lasted for 28 days, and it had a completely randomized 2 × 3 factorial design with two levels of dietary Arg, Lys and Met (high or low) and challenge with Clostridium perfringens (C. perfringens), Escherichia coli lipopolysaccharide (LPS) or no challenge (placebo). Increased dietary levels of Arg, Lys and Met had a beneficial effect on turkey performance and immunological parameters, and it improved selected indicators responsible for maintaining gut integrity in different challenge conditions. Under optimal conditions (with no challenge), high ArgLysMet diets did not compromise bird performance and they improved selected performance parameters in challenged birds. The immune system of turkeys was not excessively stimulated by high ArgLysMet diets, which did not disrupt the redox balance and had no negative effect on gut integrity. High ArgLysMet diets increased the expression levels of selected genes encoding nutrient transporters and tight junction proteins. However, the influence exerted by different dietary inclusion levels of Arg, Lys and Met on gut integrity was largely determined by the stressor (C. perfringens vs. LPS). Further studies are required to investigate the role of Arg, Lys and Met levels in the diet on the immune response, gut function and performance of turkeys in different challenge conditions.

Subclinical Doses of Combined Fumonisins and Deoxynivalenol Predispose Clostridium perfringens–Inoculated Broilers to Necrotic Enteritis

Fumonisins (FB) and deoxynivalenol (DON) are mycotoxins which may predispose broiler chickens to necrotic enteritis (NE). The objective of this study was to identify the effects of subclinical doses of combined FB and DON on NE. A total of 480 day-old male broiler chicks were divided into four treatment groups; 1) control group (basal diet + Clostridium perfringens); 2) necrotic enteritis group (basal diet + Eimeria maxima + C. perfringens); 3) FB + DON group (basal diet + 3 mg/kg FB + 4 mg/kg DON + C. perfringens); and 4) FB + DON + NE group (basal diet + 3 mg/kg FB + 4 mg/kg DON + E. maxima + C. perfringens). Birds in NE and FB + DON + NE groups received 2.5 × 10³E. maxima on day 14. All birds were inoculated with C. perfringens on days 19, 20, and 21. On day 35, birds in the NE, FB + DON, and FB + DON + NE groups had 242, 84, and 339 g lower BWG and a 19-, 2-, and 22-point increase in FCR respectively, than in the control group. Subclinical doses of FB + DON increased (p < 0.05) the NE lesion scores compared to the control group on day 21. On day 21, birds in the NE, FB + DON, and FB + DON + NE groups had increased (p < 0.05) serum FITC-D, lower (p < 0.05) jejunal tight junction protein mRNA, and increased (p < 0.05) cecal tonsil IL-1 mRNA compared to control group. On day 21, birds in the NE group had decreased (p < 0.05) villi height to crypt depth ratio compared to the control group and the presence of FB + DON in NE-induced birds further decreased the villi height to crypt depth ratio. Birds in the NE, FB + DON, and FB + DON + NE groups had increased (p < 0.05) C. perfringens, lower (p < 0.05) Lactobacillus loads in the cecal content, and a lower (p < 0.05) CD8⁺: CD4⁺ cell ratio in the cecal tonsils compared to the control group. It can be concluded that subclinical doses of combined FB and DON predispose C. perfringens-inoculated birds to NE, and the presence of FB + DON in NE-induced birds exacerbated the severity of NE.

Anticoccidial Vaccination Is Associated with Improved Intestinal Health in Organic Chickens

Simple Summary

In recent years, the number of organic chicken farms has increased. Chickens can be infected by single-cell parasites, coccidia, which cause lesions in the lining of the intestine leading to poor growth and sometimes death (coccidiosis). This infection can also lead to overgrowth in the intestine of a bacterium, Clostridium perfringens, that may cause further damage (necrotic enteritis). Prevention is often achieved by adding substances in the feed that will slow down the development of parasites and bacteria, but this is not allowed in organic farming. The aim of this study was to investigate if vaccination against coccidia can prevent these diseases in organic chickens. Vaccinated chickens developed milder gut lesions, had fewer and less damaging C. perfringens, and had similar or higher body weight compared to unvaccinated chickens six weeks after vaccination. No deaths from coccidiosis or necrotic enteritis occurred among vaccinated chickens while some unvaccinated chickens died from these diseases. We conclude that vaccination against coccidia benefits organic chickens. This study provides knowledge supporting further development of the organic chicken industry. The results are also of relevance to the management of coccidiosis and necrotic enteritis in conventional broilers.

Abstract

Eimeria spp. and Clostridium perfringens (CP) are pathogens associated with coccidiosis and necrotic enteritis (NE) in broiler chickens. In this study we evaluated the effect of anticoccidial vaccination on intestinal health in clinically healthy organic Ross 308 chickens. On each of two farms, one unvaccinated flock (A1 and B1) was compared to one vaccinated flock (A2 and B2) until ten weeks of age (WOA). Faecal oocysts were counted weekly, and species were identified by PCR (ITS-1 gene). Lesion scoring, CP quantification and PCR targeting the CP NetB toxin gene were performed at three, four, and six WOA and chickens were weighed. Necropsies were performed on randomly selected chickens to identify coccidiosis/NE. Oocyst shedding peaked at three WOA in all flocks. Later oocyst shedding (E. tenella/E. maxima) in unvaccinated flocks at 5–7 WOA coincided with coccidiosis/NE. Although results differed somewhat between farms, vaccination was associated with lower intestinal lesion scores, reduced caecal CP counts, lower proportions of netB-positive CP, lower body weight at three–four WOA, and similar or slightly increased body weight at six WOA. In conclusion, the intestinal health of organic broilers can benefit from anticoccidial vaccination when oocyst exposure levels are high.

Effect of Porcine Clostridium perfringens on Intestinal Barrier, Immunity, and Quantitative Analysis of Intestinal Bacterial Communities in Mice

Clostridium perfringens (C. perfringens) is one of the main pathogens which can cause a range of histotoxic and enteric diseases in humans or animals (pigs, or broilers). The Centers for Disease Control and Prevention (CDC) estimates these bacteria cause nearly 1 million illnesses in the United States every year. For animal husbandry, necrotizing enteritis caused by C. perfringens can cost the global livestock industry between $2 billion and $6 billion per year. C. perfringens-infected animals can be isolated for its identification and pathology. A suitable animal model is one of the essential conditions for studying the disease pathogenesis. In previous studies, mice have been used as subjects for a variety of Clostridium perfringens toxicity tests. Thus, this study was designed to build a mouse model infected porcine C. perfringens which was isolated from the C.perfringens-infected pigs. A total of 32 6-week-old male C57BL/6 mice were randomly divided into four groups. Control group was orally administrated with PBS (200 μL) on day 0. Low group, Medium group, and High group were gavaged with 200 ul of PBS resuspension containing 8.0 × 10⁷ CFU, 4.0 × 10⁸ CFU, and 2.0 × 10⁹ CFU, respectively. We examined growth performance, immune status, intestinal barrier integrity, apoptosis-related genes expression, and copies of C. perfringens in mice. The results showed that the growth performance declined and intestinal structure was seriously damaged in High group. Meanwhile, pro-inflammatory factors (IL-1β, TNF-α, and IL-6) were significantly increased (P < 0.05) in High group compared to other groups. The tight junctions and pro-apoptosis related genes' expression significantly decreased (P < 0.05) in High group, and high dose caused a disruption of intestinal villi integrity and tissue injury in the jejunum of mice. In addition, the enumerations of C. perfringens, Escherichia coli, and Lactobacillus explained why the gut of High group mice was seriously damaged, because the C. perfringens and Escherichia coli significantly enriched (P < 0.05), and Lactobacillus dramatically decreased (P < 0.05). Overall, our results provide an experimental and theoretical basis for understanding the pathogenesis and exploring the effects of porcine C. perfringens on mice.

Lighting program as a management tool for broilers raised without antibiotics - impact on productivity and welfare

1. This study investigated the impact of photoperiod on the productivity and welfare of broilers reared without antibiotics (RWA).2. A total of 8,064 mixed sex Ross 308 broilers were allocated to two trials. Lighting treatments were 14L:10D, 17L:7D, 20L:4D or 23L:1D.3. Significance defined when P≤0.05 and trends noted when P≤0.10. Highest body weights and feed consumption were found in the 4D treatment. Longer dark periods resulted in improved feed conversion. Uniformity was improved with 1D.4. Heterophil/lymphocyte ratios were highest in birds reared on 1D. Longer photoperiods negatively impacted gait and footpad scores. Birds spent more time performing feeding behaviours under longer photoperiods. Birds reared under 1 and 10D spent more time standing while those under 4 and 7D spent more time preening. Birds raised on 4D spent more time environmental pecking, while object pecking occurred more under 10D. Condemnations were lowest in birds reared under 7D.5. In conclusion, rearing RWA broilers on longer photoperiods negatively impacted welfare, as indicated by poorer mobility, higher stress, more severe footpad lesions and altered behaviour.

Vaccines Using Clostridium perfringens Sporulation Proteins Reduce Necrotic Enteritis in Chickens

Clostridium perfringens is the prevalent enteric pathogen in humans and animals including chickens, and it remains largely elusive on the mechanism of C. perfringens-induced enteritis because of limited animal models available. In this study, we investigated the role of C. perfringens sporulation proteins as vaccine candidates in chickens to reduce necrotic enteritis (NE). C. perfringens soluble proteins of vegetative cells (CP-super1 and CP-super2) and spores (CP-spor-super1 and CP-spor-super2) were prepared, and cell and chicken experiments were conducted. We found that deoxycholic acid reduced C. perfringens invasion and sporulation using the Eimeria maxima and C. perfringens co-infection necrotic enteritis (NE) model. C. perfringens enterotoxin (CPE) was detected in the CP-spor-super1&2. CP-spor-super1 or 2 induced cell death in mouse epithelial CMT-93 and macrophage Raw 264.7 cells. CP-spor-super1 or 2 also induced inflammatory gene expression and necrosis in the Raw cells. Birds immunized with CP-spor-super1 or 2 were resistant to C. perfringens-induced severe clinical NE on histopathology and body weight gain loss. CP-spor-super1 vaccine reduced NE-induced proinflammatory Ifnγ gene expression as well as C. perfringens luminal colonization and tissue invasion in the small intestine. Together, this study showed that CP-spor-super vaccines reduced NE histopathology and productivity loss.

Riboflavin and Bacillus subtilis effects on growth performance and woody-breast of Ross 708 broilers with or without Eimeria spp. challenge

This study was conducted to assess the effects of the dietary supplementation of riboflavin (as a bile salt hydrolase [BSH] inhibitor) and Bacillus subtilis on growth performance and woody breast of male broilers challenged with Eimeria spp. Intestinal bacteria, including supplemented probiotics, can produce BSH enzymes that deconjugate conjugated bile salts and reduce fat digestion. A 3 × 2 × 2 (riboflavin × Bacillus subtilis × Eimeria spp. challenge) factorial arrangement of treatments in randomized complete block design was used. On d 14, birds were gavaged with 20× doses of commercial cocci vaccine (Coccivac^R-B52, Merck Animal Health, Omaha, NE). Dietary treatment of riboflavin and B. subtilis did not affect body weight (BW), body weight gain (BWG), and feed conversion (FCR) d 0 to 14 and overall d 0 to 41. Eimeria spp challenge reduced BWG, feed intake (FI), and increased FCR between d 14 to 28, but increased BWG and lowered FCR between d 28 to 35. There were no effects of the Eimeria spp. challenge on the overall d 0 to 41 FCR and FI, but BWG was reduced. Eimeria spp. challenge increased the abdominal fat pad weight and slight woody breast incidences on processed birds on d 42. Dietary inclusion of B. subtilis and riboflavin at tested levels did not help birds to mitigate the negative impact of Eimeria spp. challenge to enhance the growth performance.