Effects of Bacillus subtilis and coccidial vaccination on cecal microbial diversity and composition of Eimeria-challenged male broilers

Exploring the interplay between Eimeria spp. infection and the host: understanding the dynamics of gut barrier function

Coccidiosis is a global disease caused by protozoans, typically including Eimeria spp., which pose a significant threat to the normal growth and development of young animals. Coccidiosis affects mainly the gut, where parasite proliferation occurs. The intestinal barrier, which consists of chemical, mechanical, biological, and immune defences, plays a crucial role in protecting the host against pathogens, xenobiotics, and toxins present in the gastrointestinal tract. When animals ingest sporulated Eimeria spp. oocysts, these parasites primarily reproduce in the intestinal tract, causing damage to the structure and function of the intestine. This disruption of intestinal homeostasis adversely affects animal health. Numerous studies have also revealed that Eimeria-infected animals experience slower bone growth rates, inferior meat quality, reduced egg production and quality, as well as impaired growth and development. Therefore, the purpose of this review is to examine the underlying mechanisms through which Eimeria spp. regulate intestinal damage and disturb the balance of the internal environment. Specifically, this review will focus on their effects on the structural basis of the host intestine's chemical, mechanical, biological and immune barriers. This understanding is crucial for the development of effective drugs to prevent the invasion of Eimeria spp. into the intestine, which is of paramount importance for maintaining host health.

Alternatives to antibiotics against coccidiosis for poultry production: the relationship between immunity and coccidiosis management – a comprehensive review

Avian coccidiosis is a protozoan infection caused by numerous Eimeria parasitic species and mainly affects the bird’s gastrointestinal tract and results in a reduction of the bird ‘ability to absorb nutrients, slower growth, with a higher mortality rate. According to recent research, immune-based treatments, such as dietary immunomodulating feed additives and recombinant vaccines, can help the hosts protect themselves from intracellular parasites and reduce inflammatory reactions caused by parasites. Coccidiosis control in the post-antiparasitic stage requires thoroughly investigation of the intricate relationships between the parasites, host defense system, enteroendocrine system, and gut microbiome contributing to coccidian infections. To produce a vaccine, it is crucial to explore the defense mechanism of the intestine’s immune machinery and to identify many effector molecules that act against intracellular parasites. Due to the massive usage of chemical anticoccidial drugs, coccidiosis developed resistant against most commonly used anticoccidials; therefore, numerous researches focused on the usage of safe natural anticoccidials such as probiotics, prebiotics, organic acids, and essential oils to counteract such resistance problem. This review describes how host immunity responds to coccidial infection in chickens and the use of some nonantiparasitic safe natural alternative controls to counter the disease. It would throw the light on the possibility of developing effective therapies against Eimeria to alleviate the detrimental effects of avian coccidiosis.

Impact of commercial gut health interventions on caecal metagenome and broiler performance

BACKGROUND

Maintaining gut health is a persistent and unresolved challenge in the poultry industry. Given the critical role of gut health in chicken performance and welfare, there is a pressing need to identify effective gut health intervention (GHI) strategies to ensure optimal outcomes in poultry farming. In this study, across three broiler production cycles, we compared the metagenomes and performance of broilers provided with ionophores (as the control group) against birds subjected to five different GHI combinations involving vaccination, probiotics, prebiotics, essential oils, and reduction of ionophore use.

RESULTS

Using a binning strategy, 84 (≥ 75% completeness, ≤ 5% contamination) metagenome-assembled genomes (MAGs) from 118 caecal samples were recovered and annotated for their metabolic potential. The majority of these (n = 52, 61%) had a differential response across all cohorts and are associated with the performance parameter - European poultry efficiency factor (EPEF). The control group exhibited the highest EPEF, followed closely by the cohort where probiotics are used in conjunction with vaccination. The use of probiotics B, a commercial Bacillus strain-based formulation, was determined to contribute to the superior performance of birds. GHI supplementation generally affected the abundance of microbial enzymes relating to carbohydrate and protein digestion and metabolic pathways relating to energy, nucleotide synthesis, short-chain fatty acid synthesis, and drug-transport systems. These shifts are hypothesised to differentiate performance among groups and cycles, highlighting the beneficial role of several bacteria, including Rikenella microfusus and UBA7160 species.

CONCLUSIONS

All GHIs are shown to be effective methods for gut microbial modulation, with varying influences on MAG diversity, composition, and microbial functions. These metagenomic insights greatly enhance our understanding of microbiota-related metabolic pathways, enabling us to devise strategies against enteric pathogens related to poultry products and presenting new opportunities to improve overall poultry performance and health. Video Abstract.

Effects of dietary Bacillus subtilis 14823 on growth performance, gut barrier integrity and inflammatory response of broilers raised in a stressful tropical environment

Heat stress (HS) has become a major concern for the poultry industry in many countries. HS impacts gut health by causing damaged mucosal microstructures, increased oxidative stress, weakened immunity, and heightened permeability to toxins and poultry pathogens. We investigated the potential benefits to broiler chickens subjected to HS of dietary supplementation with Bacillus subtilis 14823. Growth performance, gut barrier integrity, and expressions of inflammatory cytokines were analyzed. The results indicated that dietary supplementation with B. subtilis spores at concentrations of 1 × 106 CFU/g of feed (BS6 group) and 1 × 107 CFU/g of feed (BS7 group) improved body weight and body weight gain during d 0-42 (P < 0.05), while the feed intake of the BS7 group was highest (P < 0.05). Additionally, the BS6 group showed a better feed conversion ratio than the control (CON) group (P < 0.05). The BS7 group showed the lowest serum fluorescein isothiocyanate-dextran levels (P < 0.05), and both the BS6 and BS7 groups showed lower corticosterone levels than the CON group (P < 0.05). Additionally, both the BS6 and BS7 groups demonstrated increased villi height and villus height/crypt depth ratio, along with decreased crypt depth in the duodenum and ileum (P < 0.05). However, only the BS7 group exhibited greater improvements than the CON group in the jejunum at d 35. Furthermore, at d 14 and 35, mRNA expressions of occludin, claudin-1, and tight junction protein-1 in the jejunum were upregulated (P < 0.05), and expression levels of five inflammatory cytokine genes were downregulated in the ileum (P < 0.05). Our findings provide new insights and evidence supporting the application of B. subtilis 14823 for enhancing growth performance, gut barrier integrity, and modulating inflammatory cytokines in broilers.

Alterations in Ileal Microbiota and Fecal Metabolite Profiles of Chickens with Immunity to Eimeria mitis

Coccidiosis, caused by different species of Eimeria parasites, is an economically important disease in poultry and livestock worldwide. This study aimed to investigate the changes in the ileal microbiota and fecal metabolites in chickens after repeated infections with low-dose E. mitis. The chickens developed solid immunity against a high dose of E. mitis infection after repeated infections with low-dose E. mitis. The composition of the ileal microbiota and the metabonomics of the Eimeria-immunized group and the control group were detected using 16S rRNA sequencing and liquid chromatography-mass spectrometry (LC-MS). The relative abundance of Neisseria, Erysipelotrichaceae, Incertae sedis, Coprobacter, Capnocytophaga, Bifidobacterium, and the Ruminococcus torques group declined in the Eimeria-immunized chickens, whereas Alloprevotella, Staphylococcus, Haemophilus, and Streptococcus increased. Furthermore, 286 differential metabolites (including N-undecylbenzenesulfonic acid, 1,25-dihydroxyvitamin D3, gluconic acid, isoleucylproline, proline, and 1-kestose) and 19 significantly altered metabolic pathways (including galactose metabolism, ABC transporters, starch and sucrose metabolism, the ErbB signaling pathway, and the MAPK signaling pathway) were identified between the Eimeria-immunized group and the control group. These discoveries will help us learn more about the composition and dynamics of the gut microbiota as well as the metabolic changes in chickens infected with Eimeria spp.

Effects of Eimeria challenge on growth performance, intestine integrity, and cecal microbial diversity and composition of yellow broilers

The invasion of Eimeria causes damage to the intestinal barrier, nutrient leakage, and microbial imbalance in poultry. We aimed to investigate the effects of Eimeria infection on growth performance, intestinal integrity, and cecal microbial diversity and composition of yellow broilers. A total of 180 male yellow broilers were randomly divided into an unchallenged control and an Eimeria challenge treatment group within 18 floor pens (10 chicks/pen, 9 replicate pens/group). On day 10, 90 chicks received a cocktail of E. maxima, E. acervulina, and E. tenella oocysts (105/chick) to induce coccidial infection, and the other 90 received an aliquot of PBS. The Eimeria challenge resulted in increased bird feed consumption and FCR from day 11 to 21 (all P < 0.01). Higher fecal Eimeria counts, duodenal, jejunal, and cecal lesions were observed in the challenge group on day 12, 15, 15, 18 respectively (all P < 0.05). Furthermore, the infected birds had larger livers and small intestines, deeper villus crypt, and decreased expression of Claudin-1 on day 21 (all P < 0.05). The 16S rRNA sequencing indicated that alpha diversity (Sobs, Shannon, Simpson, Ace, or Chao) of cecal microbials was not affected by Eimeria challenge (all P > 0.05). However, the PCoA and LEfSe analyses indicated that the Eimeria challenge altered microbial distribution by decreasing the abundance of Firmicutes and enriching the abundance of Proteobacteria at the phylum level. At the genus level, Clostridia vadin BB60 and Lachnospiraceae NK4A136 group were reduced, while Escherichia-Shigella were enriched in the challenged yellow broilers (all P < 0.05). Correlation analyses demonstrated that the birds with higher Lachonospiraceae NK4A136 group and Clostridia vadin BB60, and lower Escherichia-Shigella in their cecal content gained more BW and reached a lower FCR from day 11 to 21 (all P < 0.05). In conclusion, Eimeria infection compromised feed efficiency of yellow broilers by damaging intestinal barrier and shifting cecal microbiota towards colonizers associated with poor performance. Restoring the dysbiotic microbiome could be a potential strategy for improving feed efficiency in yellow broilers under coccidial challenge.

Intestinal Microbiome Profiles in Broiler Chickens Raised with Different Probiotic Strains

The composition of the intestinal microbiota can influence the metabolism and overall functioning of avian organisms. Therefore, the objective of this study was to evaluate the effect of three different probiotics and an antibiotic on the microbiomes of 1.400 male Cobb® broiler raised for 42 days. The experiment was conducted with the following treatments: positive control diet (basal diet + antibiotic); negative control diet (basal diet without antibiotic and without probiotic); basal diet + Normal Avian Gut Flora (NAGF); basal diet + multiple colonizing strain probiotics (MCSPs); and basal diet + non-colonizing single strain probiotics (NCSSPs). The antibiotic (enramycin-antibiotic growth promoter) and probiotics were administered orally during all experiment (1 to 42 days), mixed with broiler feed. To determine the composition of the microbiota, five samples of ileal digesta were collected from 42-day-old chickens of each experimental group. The alpha and beta diversity of the ileal microbiota showed differences between the groups. MCSPs presented greater richness and uniformity compared to the positive control, negative control, and NCSSPs treatments, while the negative control exhibited greater homogeneity among samples than NCSSPs. MCSPs also showed a higher abundance of the genus Enterococcus. There were differences between the groups for low-abundance taxa (<0.5%), with NAGF showing higher levels of Delftia, Brevibacterium, and Bulleidia. In contrast, NCSSPs had a higher abundance of Ochrobactrum, Rhodoplanes, and Nitrospira. It was concluded that the treatments analyzed in this study induced modulations in the ileal microbiota of the chickens examined.

Effects of monensin sodium and live attenuated oocyst vaccine as coccidiosis management programs on productive performance, bone quality and mineral utilisation in broiler chickens

1. The following study was conducted to evaluate the influence of coccidiosis vaccine-induced metabolic stress on the utilisation of minerals in broilers. The starter, grower and finisher phase diets, including macro- and micro minerals at the recommended levels for the breed standards, were fed to chickens between 1 and 39 d of age.2. A total of 486, one-d-old male broilers were randomly distributed into three coccidiosis management programs (CMP) with six replications each. The CMP comprised: monensin sodium (MON), coccidiosis vaccine (VAC), not treated with MON or VAC (CNT).3. No significant differences between CMP were observed for body weight and weight gain among treatments. When compared to the CNT, the VAC program increased feed intake (P < 0.05) between d 1 to 13 and 14 to 26, while FCR worsened in the latter (P < 0.05) and the former (P = 0.05) periods.4. For birds in the MON and VAC programs, tibia bone length at d 13 and bone diameter at d 39 were both enhanced (P < 0.05). Meat yield characteristics were comparable among the CMP.5. Faeces of VAC birds had a lower (P < 0.05) dry matter and ash content than those in CNT program. CMP had no effect on serum or bone mineral concentrations at any point in time. For minerals, Mg, Na, and K faecal excretion was reduced (P < 0.01) as a result of the VAC program at d 13 with a trend at d 26.6. Compared to the CNT, the VAC program decreased the percentage ratio of drip loss (P = 0.08), water holding capacity (P < 0.01) and cooking loss (P < 0.01) in breast meat.7. Overall, the results showed that current broiler industry practices are capable of meeting the mineral needs of broilers vaccinated against coccidiosis.

Dietary Bacillus spp. supplementation to both sow and progenies improved post-weaning growth rate, gut function, and reduce the pro-inflammatory cytokine production in weaners challenged with Escherichia coli K88

BACKGROUND

The use of probiotics (PRO) in late gestation sow and their impact on progenies' performance during the post-weaning stage has received more attention from the researchers recently. This study aimed to analyze the effect of probiotic mixture (Bacillus subtilis and Bacillus licheniformis) on both sow and offspring's performance.

METHODS

First experiment (Exp.1) was conducted from the 100th day of gestation through to post-weaning. A total of twenty sows and their litters were assigned to one of two dietary treatments, Control (CON) based diet and PRO- CON+ 0.05% probiotic mixture. Dietary treatments were arranged in a split-plot pattern with sow and weaner treatment (CON and PRO diet) as the main and sub plot. Exp.2. E. coli challenge study was carried out two weeks after weaning with 40 piglets. Dietary treatments remained same while all pigs were orally administered with a 1.5 ml suspension of 1010 CFU of K88 strain of E. coli per ml.

RESULT

PRO group sow showed significantly decreased backfat thickness difference and body weight difference after farrowing and at the end of weaning d21. The nutrient digestibility of PRO group sows was significantly higher at the end of weaning. Moreover, piglets born from PRO group sow showed higher weaning weight and tend to increase average daily gain at the end of d21. The addition of mixed probiotic in sow and weaner diet had suppressed the production of TNF-α and interleukin-6 in E. coli challenged pigs. The phyla Firmicutes and Bacteroidetes in E. coli -challenged pigs were highly abundant while, the relative abundance of clostridium_sensu_stricto_1 at genus level was significantly reduced by the inclusion of probiotic in both the sow and weaner diet. Also, taxonomic distribution analysis showed significantly lower prevalence of Clostridium and Brachyspira and higher prevalence of Lactobacilli in E. coli-challenged pigs that were born from PRO group sow and fed CON and PRO weaner diet.

CONCLUSION

This study reveals that the inclusion of 0.05% mixed probiotics (Bacillus spp.) to both sow and their progenies diet would be more beneficial to enhance the post-weaning growth rate, gut health, and immune status of E. coli challenged pigs.

Management and control of coccidiosis in poultry - A review

Poultry coccidiosis is an intestinal infection caused by an intracellular parasitic protozoan of the genus Eimeria. Coccidia-induced gastrointestinal inflammation results in large economic losses, hence finding methods to decrease its prevalence is critical for industry participants and academic researchers. It has been demonstrated that coccidiosis can be effectively controlled and managed by employing anticoccidial chemical compounds. However, as a result of their extensive use, anticoccidial drug resistance in Eimeria species has raised concerns. Phytochemical/herbal medicines (Artemisia annua, Bidens pilosa, and garlic) seem to be a promising strategy for preventing coccidiosis, in accordance with the "anticoccidial chemical-free" standards. The impact of herbal supplements on poultry coccidiosis is based on the reduction of oocyst output by preventing the proliferation and growth of Eimeria species in chicken gastrointestinal tissues and lowering intestinal permeability via increased epithelial turnover. This review provides a thorough up-to-date assessment of the state of the art and technologies in the prevention and treatment of coccidiosis in chickens, including the most used phytochemical medications, their mode of action, and the applicable legal framework in the European Union.

Efficacy of Bacillus subtilis to replace in-feed antibiotics of broiler chickens under necrotic enteritis-challenged experiments: a systematic review and meta-analysis

Necrotic enteritis (NE) and coccidiosis are among the most prevalent infectious diseases in broiler chickens, contributing to large profitability losses. Bacillus subtilis is a promising direct-fed probiotic to counter various pathogens infection in broiler chickens. Here, we performed a meta-analysis to investigate the effects of B. subtilis on broiler chickens performance. A total of 28 studies were selected according to a PRISMA checklist. Random-effect model and mixed-effect model of meta-analysis were fitted to estimate the overall effects of B. subtilis (BS) treatment compared to either the control group (CON) or NE-infected group (NEinf) as a baseline. Hedges' g effect size and its variance were used as estimators of standardized mean difference (SMD) calculation where the results were presented at a 95% confidence interval (95% CI) of the SMD. Overall, NEinf broiler chickens depressed (P < 0.01) body weight (BW), average daily gain (ADG), and feed intake, and elevated (P < 0.01) feed conversion ratio (FCR). Treatment with BS improved ADG and final BW of NEinf with no difference (P = 0.15) between BS and antibiotics (AB), indicating that they had comparable efficacy to treat NE in broiler chickens. BS supplemented to uninfected CON (BSS) improved (P < 0.01) final BW, ADG, and FCR. Compared to CON, BS, and AB failed to recover the FCR but these treatments decreased (P < 0.01) FCR when compared to the NEinf group with similar efficacy (P = 0.97). As expected, NEinf birds had a higher mortality rate (P < 0.01) and higher lesion score (P < 0.01) compared to CON, and treatment using AB and BS successfully decreased (P < 0.01) the mortality rate and lesion score. Compared to BS, AB was more effective to lower (P = 0.01) mortality rate, but comparable (P = 0.65) to minimize lesion score. To conclude, B. subtilis could be an effective natural additive to replace in-feed antibiotics in broiler chickens challenged with C. perfringens. However, the efficacy to reduce mortality rate was better with antibiotics treatment.

A meta-analysis of the effect of Eimeria spp. and/or Clostridium perfringens infection on the microbiota of broiler chickens

Coccidiosis in chickens is caused by Eimeria spp. The infection provides a growth advantage to Clostridium perfringens (CP), frequently leading to necrotic enteritis. One approach to alleviate the negative impacts of the diseases is to improve the bacterial composition in chickens, and many experiments investigating chicken enteric health in recent years include the characterization of the bacterial microbiota. This meta-analysis synthesized the data of studies investigating the intestinal microbiota after infection with coccidia and/or CP to provide a basis for future research. Inclusion criteria were that experiments contained a group infected with one or both pathogens and an uninfected control group, the use of 16SrRNA Illumina sequencing and the availability of raw data. A total of 17 studies could be included. Meta-analyses of 3 different data sets were performed: 1 on data of 9 experiments on chickens infected with coccidia only; the second on data of 4 studies on chickens infected with CP only; the third on raw data of 8 experiments with chickens infected with coccidia and CP. The meta-analysis of relative abundance and alpha diversity of the data sets was performed in R using the SIAMCAT and metafor packages. The number of families of interest identified by the analyses of experiments with infection with coccidia only, CP only and the combined infection were 23, 2, and 29, respectively. There was an overlap of 13 families identified by analyses of experiments with infection with coccidia only and of experiments with the combined infections. Machine learning was not able to find a model to predict changes of the microbiota in either 1 of the 3 analyses. Meta-analyses of functional profiles showed a more uniform reaction to the infections with the relative abundance of many pathways significantly altered. Alpha diversity was not affected by infection with either pathogen or the combination. In conclusion, the heterogeneity of these microbiota studies makes recognizing common trends difficult, although it seems that coccidia infection affects the microbiota more than an infection with CP. Future studies should focus on the bacterial functions that are changed due to these infections using metagenome techniques.

Mechanisms and applications of probiotics in prevention and treatment of swine diseases

Probiotics can improve animal health by regulating intestinal flora balance, improving the structure of the intestinal mucosa, and enhancing intestinal barrier function. At present, the use of probiotics has been a research hotspot in prevention and treatment of different diseases at home and abroad. This review has summarized the researchers and applications of probiotics in prevention and treatment of swine diseases, and elaborated the relevant mechanisms of probiotics, which aims to provide a reference for probiotics better applications to the prevention and treatment of swine diseases.

Effects of a Dietary Multi-Strain Probiotic and Vaccination with a Live Anticoccidial Vaccine on Growth Performance and Haematological, Biochemical and Redox Status Indicators of Broiler Chickens

A total of 256 male Ross 308 chickens were assigned to four treatments in a 2 × 2 factorial design with two levels of the anticoccidial vaccine (ACV) Livacox T (none or 1 × dose) with or without dietary supplementation with the probiotic Protexin^® (P). The growth performance parameters for the test periods (1-21, 22-42, and 1-42 d) and oocyst per gram (OPG) at weekly intervals were analysed. Blood samples were collected at 16 post-vaccination (pv) days to measure selected haematological, biochemical, redox, and immunological parameters. ACV administration worsened the performance parameters of the chickens for 1-21 d pv, while supplementation with P reduced this negative effect with a significant improvement in 1-21 d body weight gain and feed conversion ratio. ACV administration increased % phagocytic cells (%PC), phagocytic index (PI), respiratory burst activity, proportion of monocytes, and activities of aspartate aminotransferase (AST) and lactate dehydrogenase, while it decreased the catalase activity and concentration of malondialdehyde and peroxides. The dietary administration of P significantly increased counts of red blood cells and white blood cells and increased %PC and PI, while it decreased the heterophil proportion, heterophil/lymphocyte ratio (p = 0.059), and alanine aminotransferase and AST activities. The oocyst counts were comparable in all sampling periods, except on 14 d pv, as supplementation with P significantly decreased 14 d OPG, thus indicating a positive influence of P on immunity development. In conclusion, dietary supplementation with P led to improved performance, better immunity, and benefits in health status in broilers vaccinated with the ACV, without interfering with the circulating vaccine strains.

Chicken Gut Microbiota Responses to Dietary Bacillus subtilis Probiotic in the Presence and Absence of Eimeria Infection

Coccidiosis is a well-known poultry disease that causes the severe destruction of the intestinal tract, resulting in reduced growth performance and immunity, disrupted gut homeostasis and perturbed gut microbiota. Supplementation of probiotics were explored to play a key role in improving growth performance, enhancing innate and adaptive immunity, maintaining gut homeostasis and modulating gut microbiota during enteric infection. This study was therefore designed to investigate the chicken gut whole microbiota responses to Bacillus subtilis (B. subtilis) probiotic feeding in the presence as well as absence of Eimeria infection. For that purpose, 84 newly hatched chicks were assigned into four groups, including (1) non-treated non-challenged control group (CG - ET), (2) non-treated challenged control group (CG + ET), (3) B. subtilis-fed non-challenged group (BS - ET) and (4) B. subtilis-fed challenged group (BS + ET). CG + ET and BS + ET groups were challenged with Eimeria tenella (E. tenella) on 21 day of housing. Our results for Alpha diversity revealed that chickens in both infected groups (CG + ET and BS + ET) had lowest indexes of Ace, Chao 1 and Shannon, while highest indexes of Simpson were found in comparison to non-challenged groups (CG - ET and BS - ET). Firmicutes was the most affected phylum in all experimental groups following Proteobacteria and Bacteroidota, which showed increased abundance in both non-challenged groups, whereas Proteobacteria and Bacteroidota affected both challenged groups. The linear discriminant analysis effect size method (lEfSe) analysis revealed that compared to the CG + ET group, supplementation of probiotic in the presence of Eimeria infection increased the abundance of some commensal genera, included Clostridium sensu stricto 1, Corynebacterium, Enterococcus, Romboutsia, Subdoligranulum, Bacillus, Turicibacter and Weissella, with roles in butyrate production, anti-inflammation, metabolic reactions and the modulation of protective pathways against pathogens. Collectively, these findings evidenced that supplementation of B. subtilis probiotic was positively influenced with commensal genera, thereby alleviating the Eimeria-induced intestinal disruption.

Caecal microbiota composition of experimental inbred MHC-B lines infected with IBV differs according to genetics and vaccination

Interactions between the gut microbiota and the immune system may be involved in vaccine and infection responses. In the present study, we studied the interactions between caecal microbiota composition and parameters describing the immune response in six experimental inbred chicken lines harboring different MHC haplotypes. Animals were challenge-infected with the infectious bronchitis virus (IBV), and half of them were previously vaccinated against this pathogen. We explored to what extent the gut microbiota composition and the genetic line could be related to the immune response, evaluated through flow cytometry. To do so, we characterized the caecal bacterial communities with a 16S rRNA gene amplicon sequencing approach performed one week after the IBV infectious challenge. We observed significant effects of both the vaccination and the genetic line on the microbiota after the challenge infection with IBV, with a lower bacterial richness in vaccinated chickens. We also observed dissimilar caecal community profiles among the different lines, and between the vaccinated and non-vaccinated animals. The effect of vaccination was similar in all the lines, with a reduced abundance of OTU from the Ruminococcacea UCG-014 and Faecalibacterium genera, and an increased abundance of OTU from the Eisenbergiella genus. The main association between the caecal microbiota and the immune phenotypes involved TCR_ϒδ expression on TCR_ϒδ⁺ T cells. This phenotype was negatively associated with OTU from the Escherichia-Shigella genus that were also less abundant in the lines with the highest responses to the vaccine. We proved that the caecal microbiota composition is associated with the IBV vaccine response level in inbred chicken lines, and that the TCR_ϒδ⁺ T cells (judged by TCR_ϒδ expression) may be an important component involved in this interaction, especially with bacteria from the Escherichia-Shigella genus. We hypothesized that bacteria from the Escherichia-Shigella genus increased the systemic level of bacterial lipid antigens, which subsequently mitigated poultry γδ T cells.

Effects of dietary bacitracin or Bacillus subtilis on the woody breast myopathy-associated gut microbiome of Eimeria spp. challenged and unchallenged broilers

Study suggested that dysbiosis of the gut microbiota may affect the etiology of woody breast (WB). In the current study, the cecal microbiota and WB in chickens fed three different diets were investigated. A total of 504 male chicks were used in a randomized complete block design with a 3 (Diet) × 2 (Challenge) factorial arrangement of treatments with 6 replicates per treatment, 6 treatments per block, and 14 birds per treatment. The experimental diets were a control diet (corn-soybean meal basal diet), an antibiotic diet (basal diet + 6.075 mg bacitracin/kg feed), and a probiotic diet (basal diet + 2.2 × 10⁸ CFU Bacillus subtilis PB6/kg feed). On d 14, birds that were assigned to the challenge treatment received a 20 × live cocci vaccine. On d 41, breast muscle hardness in live birds was palpated and grouped into normal (NB) and WB phenotypes. Cecal contents were collected and their bacterial compositions were analyzed and compared. The genomic DNA of the cecal contents was extracted and the V3 and V4 regions of 16S rRNA gene were amplified and sequenced via an Illumina MiSeq platform. There were no differences (P > 0.05) in Shannon and Chao 1 indexes between the challenges, diets, and phenotypes (NB vs. WB). However, there was a difference (P = 0.001) in the beta diversity of the samples between the challenged and nonchallenged groups. Relative bacterial abundance differed (false discovery rate, FDR < 0.05) between the challenge treatments, but there were no significant differences (FDR > 0.05) among the three diets or two phenotypes. Predicted energy metabolism, nucleotide metabolism, and amino acid and coenzyme biosynthesis activities only differed (q-value < 0.05) between challenged and nonchallenged groups. The cocci challenge altered the gut microbial composition on Butyricicoccus pullicaecorum, Sporobacter termitidis, and Subdoligranulum variabile, but the dietary antibiotic and probiotic treatments did not impact gut microbial composition. No strong association was found between WB myopathy and gut microbial composition in this study.

Understanding the interactions between Eimeria infection and gut microbiota, towards the control of chicken coccidiosis: a review

The gastrointestinal tract in poultry harbours a diverse microbial community that serves a crucial role in digestion and protection. Disruption of the gut environment due to Eimeria spp. parasite infection causes an imbalance in intestinal homeostasis, driving the increment of pathogens such as Clostridium species. Coccidiosis infection affects the composition and integrity of gut microbiota, resulting in elevated susceptibility to diseases that pose a serious threat to the overall health and productivity of chickens. Anticoccidial drugs have proven effective in curbing coccidiosis but with concerning drawbacks like drug resistance and drug residues in meat. The exploration of natural alternative strategies such as probiotics and phytochemicals is significant in controlling coccidiosis through modification and restoration of gut microbiota, without inducing drug resistance. Understanding the interaction between Eimeria parasites and gut microbiota is crucial for the control and prevention of coccidiosis, and the development of novel alternative treatments.

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

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

Transcriptome Analysis Revealed Ameliorative Effects of Bacillus Based Probiotic on Immunity, Gut Barrier System, and Metabolism of Chicken under an Experimentally Induced Eimeria tenella Infection

In this study, we performed transcriptome analysis in the cecum tissues of negative control untreated non-challenged (NC), positive control untreated challenged (PC), and Bacillus subtilis (B. subtilis) fed challenged chickens (BS + ET) in order to examine the underlying potential therapeutic mechanisms of Bacillus based probiotic feeding under an experimental Eimeria tenella (E. tenella) infection. Our results for clinical parameters showed that birds in probiotic diet decreased the bloody diarrhea scores, oocyst shedding, and lesion scores compared to positive control birds. RNA-sequencing (RNA-seq) analysis revealed that in total, 2509 up-regulated and 2465 down-regulated differentially expressed genes (DEGs) were detected in the PC group versus NC group comparison. In the comparison of BS + ET group versus PC group, a total of 784 up-regulated and 493 down-regulated DEGs were found. Among them, several DEGs encoding proteins involved in immunity, gut barrier integrity, homeostasis, and metabolism were up-regulated by the treatment of probiotic. Functional analysis of DEGs also revealed that some gene ontology (GO) terms related with immunity, metabolism and cellular development were significantly affected by the exposure of probiotic. Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis showed that the DEGs in the cecum of B. subtilis-fed challenged group were mainly participated in the pathways related with immunity and gut barrier integrity, included mitogen-activated protein kinase (MAPK) signaling pathway, toll-like receptor (TLR) signaling pathway, extracellular matrix (ECM)–receptor interaction, tight junction, and so on. Taken together, these results suggest that Bacillus based probiotic modulate the immunity, maintain gut homeostasis as well as barrier system and improve chicken metabolism during E. tenella infection.

Combination of Bacillus licheniformis and Salinomycin: Effect on the Growth Performance and GIT Microbial Populations of Broiler Chickens

Simple Summary

The beneficial effects of Bacillus spp. probiotic preparations used for poultry are well-documented and characterized by growth performance improvement and positive modulation of gastrointestinal tract (GIT) microbiota. Moreover, the favorable influence of salinomycin has been frequently studied as an ionophore coccidiostat, as well as an antimicrobial agent. However, limited data are available in terms of the parallel usage of both Bacillus licheniformis DSM 28710 and salinomycin in poultry diets. From a practical point of view, evaluating the potential interactions between this species and agent is crucial to assess their parallel usage, and the current study confirmed the positive effect of their mixture on the modulation of pH value in the crop and ceca, as well as the GIT microbiota, especially in the jejunum and ceca. Additionally, the results obtained in this study show positive effects of B. licheniformis on the growth performance, as well as the influence of both experimental factors used separately in the case of GIT microbiota modulations.

Abstract

The aim of the study was to investigate the effect of Bacillus licheniformis and salinomycin supplementation in broiler diets as individual factors or in combination on the growth performance, GIT morphometry, and microbiota populations. Four hundred one-day-old Ross 308 chicks were randomly distributed to four dietary treatments (10 replicates, 10 birds each). The following treatments were applied: NC—no additives; NC + SAL—salinomycin addition (60 mg/kg diet), NC + PRO—B. licheniformis DSM 28710 preparation (1.6 × 10⁹ CFU/kg; 500 mg/kg diet), and NC + SAL + PRO—combination of salinomycin and B. licheniformis. Probiotic administration resulted in improvement (p < 0.05) of the performance parameters, including body weight gain (1–10 d, and 11–22 d) and feed conversion ratio (11–22 d, 1–36 d). An interaction (p < 0.05) between experimental factors was observed in terms of lower pH values in the crop (tendency, p = 0.053) and ceca. Both factors lowered the alpha diversity and Enterobacteriaceae and promoted Bacillaceae communities in the jejunum (p < 0.05). Interactions were also observed in terms of reducing Clostridiaceae in the ceca. In conclusion, the combined use of B. licheniformis and salinomycin in broilers’ diets had beneficial effects.

Effects of Dietary Direct Fed Microbial Supplementation on Performance, Intestinal Morphology and Immune Response of Broiler Chickens Challenged With Coccidiosis

Poultry coccidiosis is a costly intestinal disease that leads to considerable tissue damage, inefficient nutrient absorption, increased mortality, and predisposition to secondary infections. This study evaluated the effects of a direct feed microbial (DFM) dietary additive on performance, intestinal morphology, and immune response of broilers during a mixed coccidiosis challenge. In total, 840 Cobb500 male broilers were randomly allocated to 3 treatments (7 replicates, 40 birds/pen) including negative control (NC) fed basal diet; positive control (PC) fed basal diet with coccidiosis challenge; and DFM supplemented diet, with coccidiosis challenge. At 15 days of age, all birds except for the NC treatment were orally gavaged with live oocysts of a commercial vaccine. On d 21 (6 days post challenge), 4 birds/pen were randomly selected and euthanized for scoring of coccidia-caused lesions in the duodenum, jejunum, and ceca. Body weight gain (BWG), feed intake (FI), and feed conversion ratio (FCR) were recorded on d 7, 14, 28, and 42. Jejunal and ileal tissue samples were taken for histomorphological assessment from 2 birds/pen on d 21. Ileal samples were also taken for mRNA expression analysis on d 14 and d 21. The DFM birds had significantly greater BWG than PC birds during d 0-21 (P < 0.05). No differences were observed among the treatment groups in terms of FI and FCR. Dietary DFM supplementation significantly reduced lesion scores in the duodenum and jejunum when compared with PC group (P < 0.05). The coccidia challenge significantly reduced (P < 0.05) ileal villus height when compared to the non-challenged group on d 21. Conversely, dietary DFM supplementation alleviated the negative effects of coccidiosis by increasing ileal villus area on d 21 (P < 0.05). The challenged birds had significantly greater expression of IFN-γ and IL-1β in the ileum on d 21. Based on these findings, dietary DFM supplementation may help restore broiler performance during the starter and early grower periods during coccidiosis, likely by maintaining gut integrity via improving intestinal morphology and also by reducing disease severity as manifested by lower lesion scores.