Bacterial Population Changes in the Ceca of Young Chickens Infected with Eimeria tenella

Necrotic enteritis in broiler chickens: disease characteristics and prevention using organic antibiotic alternatives – a comprehensive review

In line with the substantial increase in the broiler industry worldwide, Clostridium perfringens-induced necrotic enteritis (NE) became a continuous challenge leading to high economic losses, especially after banning antimicrobial growth promoters in feeds by many countries. The disease is distributed worldwide in either clinical or subclinical form, causing a reduction in body weight or body weight gain and the feed conversion ratio, impairing the European Broiler Index or European Production Efficiency Factor. There are several predisposing factors in the development of NE. Clinical signs varied from inapparent signs in case of subclinical infection (clostridiosis) to obvious enteric signs (morbidity), followed by an increase in mortality level (clostridiosis or clinical infection). Clinical and laboratory diagnoses are based on case history, clinical signs, gross and histopathological lesions, pathogenic agent identification, serological testing, and molecular identification. Drinking water treatment is the most common route for the administration of several antibiotics, such as penicillin, bacitracin, and lincomycin. Strict hygienic management practices in the farm, careful selection of feed ingredients for ration formulation, and use of alternative antibiotic feed additives are all important in maintaining broiler efficiency and help increase the profitability of broiler production. The current review highlights NE caused by C. perfringens and explains the advances in the understanding of C. perfringens virulence factors involved in the pathogenesis of NE with special emphasis on the use of available antibiotic alternatives such as herbal extracts and essential oils as well as vaccines for the control and prevention of NE in broiler chickens.

Influence of Eimeria spp. Infection on Chicken Jejunal Microbiota and the Efficacy of Two Alternative Products Against the Infection

Eimeria spp. are important intestinal pathogens of chickens (Gallus gallus domesticus). Anticoccidial feed additives, chemicals, and ionophores have traditionally been used to control Eimeria infections in broiler production. Thus, the trend toward antibiotic-free and organic production requires new approaches to coccidiosis prevention. Two not mutually exclusive methods are the use of plant extracts with antiparasitic activity and manipulation of the intestinal microbiota by pre- and probiotics. In the present study, birds were inoculated with a combination of Eimeria acervulina, Eimeria maxima, and Eimeria tenella. We profiled the jejunal microbiome at multiple time points postinfection to investigate the changes in jejunum microbiota and to identify the time point of the maximum difference between infected and noninfected birds. Additionally, we assessed the anticoccidial effects of two anecdotal treatment methods, green tea and apple cider vinegar, as well as amprolium. Green tea and apple cider vinegar had no effect on oocyst shedding, but green tea reduced the mild unspecific lesions in coccidia-infected birds; there was no influence on unspecific lesions in uninfected controls. Jejunal contents were collected on the day of the infection and 1, 2, 4, 6, 10, and 14 days postinfection (dpi) for investigation of the intestinal microbiota by 16S ribosomal (r)RNA gene sequencing. Comparison of the untreated-uninfected and the untreated-infected groups showed a maximum community dissimilarity of 10 dpi. From 4 days after infection, Clostridiales were significantly enriched at the expense of Lactobacillales in infected compared with uninfected birds. Interestingly, treatment with green tea prevented proliferation of Clostridiales induced by the coccidia and increased the relative abundance of Melainabacteria.

Interactions Between Parasites and the Bacterial Microbiota of Chickens

Except for the important role coccidia have as predisposing factors of necrotic enteritis, the role parasites play in the dynamics of a healthy microbiota of chickens is not well explored. This review describes the interactions of relevant intestinal parasites of chickens with bacteria. Infection with Eimeria spp. favor the growth of Clostridium perfringens and suppress the growth of many other bacteria by increasing viscosity and passage time of the ingesta, and by causing lesions to the intestinal mucosa that improve the availability of nutrients for C. perfringens. Conversely, there are indications that bacteria influence the course of disease after infections with Eimeria spp. Not much is known about intestinal cryptosporidiosis in chickens, but results in mice show that the intestinal microbiota induces some resistance against infection with Cryptosporidium parvum and that the innate immune response triggered by infections with cryptosporidia might have an effect on other intestinal microbes. Histomonas meleagridis depend on bacteria in vitro, and in vivo it will cause lesions in chickens only in the presence of bacteria. Blastocystis spp. are very common in chickens, but there is no information about interactions with bacteria. In humans, there is evidence of the correlation of the detection of Blastocystis and changes in the intestinal microbiota. There are indications of interactions between Ascaridia galli and various bacteria in chickens and Ascaridia spp. of mammals are known to produce various types of antimicrobial molecules. However, often the underlying mechanisms of these interactions between parasites and bacteria remain unknown and only correlations but not causation can be established.

Intercurrent coccidiosis and necrotic enteritis of chickens: rational, integrated disease management by maintenance of gut integrity

Coccidiosis and necrotic enteritis (NE) are globally common, sometimes intercurrent, diseases of poultry. The risk of NE, due to the Gram-positive bacterium Clostridium perfringens, has increased in recent years because of the voluntary or legally required withdrawal of the use of certain in-feed antibiotic growth promoters with anticlostridial activity. In-feed ionophorous anticoccidial drugs incidentally also possess anticlostridial activity. Such ionophores, although not banned, are usually precluded when live anticoccidial vaccines are used, potentially increasing yet further the risk of NE. This review provides information for the design of rational, integrated management strategies for the prevention and control of coccidiosis and NE in chickens by maintaining gut integrity. Because of differences in local availability of feed ingredients and national legislations regarding antibiotic growth promoters and anticoccidial vaccine licensing, no universal strategy is applicable. The diseases and their interactions are described under the headings of forms of disease, diagnosis, sources of infection, pathophysiological effects, predisposing factors, and control methods. Elements of gut integrity, which influences host predisposition and clinical responses to disease, include physical development, immune competence, gut enzyme activity, mucin production, gut flora and epithelial damage. Experimental studies of coccidiosis and NE are compared, and where possible reconciled, with field observations. Gaps in knowledge and necessary further experiments are identified. Insights are provided regarding interactions between coccidiosis, NE, and the use of live anticoccidial vaccines. Recent changes in NE prevalence in commercial flocks, and their possible causes, are discussed. The necessarily wide range of topics reviewed emphasizes the enormous complexity of this disease combination, and indicates the importance of a multidisciplinary approach in order to reduce its harmful impact on the world's poultry industry.

Origins of coccidiosis research in the fowl--the first fifty years

In 1910, H. B. Fantham described the life cycle of a coccidian parasite in birds. Fantham was a parasitologist at Cambridge University in the United Kingdom working for an enquiry into diseases affecting the red grouse. Despite the growing importance of the poultry industry and the realization that coccidiosis was an important disease of the fowl, little further work was carried out in the United Kingdom until coccidiosis research was initiated at the Veterinary Laboratory, Weybridge almost 30 yr later. Further progress depended upon research carried out at academic and agricultural institutions in the United States. E. E. Tyzzer at Harvard University provided the solid foundation upon which our present knowledge of coccidiosis, and the species of Eimeria involved in the disease, is based. Agricultural experiment stations (AESs) throughout the nation played an important role in communicating advances to the agricultural community. W. T. Johnson at Western Washington and, subsequently, Oregon AES made significant contributions to our understanding of the disease, as did C. A. Herrick and coworkers at Wisconsin AES, J. P. Delaplane and coworkers at Rhode Island AES, and P. P. Levine at Cornell University.

The effect of added complex carbohydrates or added dietary fiber on necrotic enteritis lesions in broiler chickens

Two trials utilizing two corn diets and four wheat diets were conducted. In Trial 2, all chicks were crop-infused at 9 d of age with Eimeria acervulina. In both trials, a broth culture of Clostridium perfringens was mixed with the diets for 3 consecutive d. Necrotic enteritis lesion scores were lowest in chickens consuming the corn diet with no C. perfringens and highest in chickens fed the wheat diets with C. perfringens. Chickens consuming a wheat diet with no added complex carbohydrates or added fiber exhibited the highest lesion score. Chickens on wheat diets with 4% new, ground, pine shavings had intestinal lesion scores intermediate to those of chickens that consumed the wheat or corn diets. Chickens consuming corn diets yielded the lowest lesion scores. Chickens provided diets containing either guar gum or pectin were not fully consumed and thus probably reduced the number of challenge organisms ingested.

Coccidial infections and gut microflora

Oral inoculations of sporulated oocysts of Eimeria acervulina, E. necatrix, E. brunetti, E. tenella, or none were given to five groups of 4-wk-old chicks. Fecal samples were taken at 1, 3, 5, 6, 7, 8, 11, 14, and 21 days postinoculation and total fecal aerobe, total fecal anaerobe, fecal lactobacilli, and fecal coliform concentrations were enumerated. Fecal aerobe concentrations increased 10-fold during the period from 3 to 8 days postinoculation. Fecal anaerobe concentrations had small increases from 3 to 6 days. Fecal lactobacilli concentrations increased with E. necatrix and E. brunetti infections but decreased with E. tenella infections. Fecal coliform concentrations increased most with the duodenal infections and increased less with posterior tract infections.

Monensin, Eimeria tenella infection, and effects on the bacterial populations in the ceca of gnotobiotic chickens

Bacteria-free chicks in separate plastic film isolators were inoculated orally with single species of bacteria. Within an isolator, half the birds were fed unmedicated feed and half received feed containing 100 ppm monensin. With clostridium perfringens as the established species of monoflora, bacterial counts from the duodenum were 10(4) times lower and counts from the ceca were three times lower in monensin-fed birds compared to unmedicated birds. Infection with Eimeria tenella stimulated an eight-fold increase in the numbers of C. perfringens in the ceca of unmedicated birds but no increase in monensin-fed birds. With Bacteroides sp. or Streptococcus faecalis as monoflora, there was no difference in the cecal or duodenal populations between medicated and unmedicated birds uninfected with coccidia. In contrast to C. perfringens, populations of Bacteroides sp. and S. faecalis in the ceca decreased five to 100-fold in both medicated and unmedicated chicks after infection with E. tenella. Duodenal populations of C. perfringens, Bacteroides sp., and S. faecalis were unaffected by the coccidial infection.

Studies on the relationship between intestinal flora and cecal coccidiosis in chicken

The bacteriological and histopathological changes in the ceca of young chickens after being infected with sporulated oocysts of Eimeria tenella were investigated. Lactobacilli and bifidobacteria showed remarkable decrease in number on the 5th day after infection, when shizont and gametocyate came to appear, and destruction of mucosa along with severe haemorrhaging was noticed. Other predominant bacteria like bacteroidaceae, catenabacteria and peptostreptococci showed only moderate and temporal decrease in number during the infection. Clostridium perfringens prolifereated after the 5th day post infection following the decline of lactobacilli and bifidobacteria. Proliferation of clostridia was so intense that the number was almost million times greater than that of the uninfected chicken at its peak on the 7th day after infection. Enterobacteria also showed a moderate but persistent increase in number. Most bacteria came to the normal population on the 10th day after infection. As for lactobacilli, bifidobacteria, clostridia and enterobacteria, the disturbances were still noticeable on the 17th day after injection. Antagonism between proliferated bacteria (clostridia and enterobacteria) and lactic acid bacteria (lactobacilli and bifidobacteria) whose intensity is suppose to be related to the cecal mucosa is suggested during cecal coccidiosis in chickens.

Reduction of Clostridium perfringens by feed additive antibiotics in the ceca of chickens infected with Eimeria tenella

Two experiments were performed ot investigate the effect of feed additive antibiotics on Clostridium perfringens and Enterobacteriaceae in the ceca of chickens infected with Eimeria tenella. In the first experiment, chickens were continuously fed rations containing thiopeptin, 2 mg./kg.; bacitracin, 20 mg./kg.; penicillin, 12 mg./kg.; or chlortetracycline, 22 mg./kg. One day after antibiotic feed was given, each bird received an oral inoculation of 30,000 E. tenella oocysts. The growth of C. perfringens was stimulated by the infection in unmedicated chickens. Dietary thiopeptin, bacitracin, penicillin, or chlortetracycline suppressed the number of C. perfringens recovered 5 and 7 days after infection. Enterobacteriaceae were increased by the infection, but dietary antibiotics did not reduce the increase. In the second experiment, chickens were given feed containing amprolium plus ethopabate, 125 plus 8 mg./kg., and a combination of the coccidiostat and one of 4 antibiotics: thiopeptin, bacitracin, penicillin, or chlortetracycline. Birds were each given an oral inoculation of 30,000 coccidiostat-resistant E. tenella oocysts. Infection resulted in an increase of C. perfringens in the unmedicated control and the coccidiostat-treated groups. Dietary thiopeptin, bacitracin, penicillin, or chlortetracycline reduced the number of C. perfringens found 5 and 7 days after infection. Counts of Enterobacteriaceae were increased by the infection, but dietary antibiotics did not suppress the increased counts. In both experiments, dietary administration of antibiotics did not reduce gross cecal lesions.

Effect of feed additive antibiotics on chickens infected with Eimeria tenella

Six experiments were carried out to study the effect of feed additive antibiotics on body weight, mortality and oocyst production in chickens infected with coccidiostat-susceptible or -resistant strain of E. tenella. Levels of antibiotic and coccidiostat in fed (mg./kg.) were: thiopeptin, 2; zinc bacitracin, 20; penicillin, 12; chlortetracycline, 22; amprolium plus ethopabate, 125 plus 8; clopidol, 125. All experiments included 7 groups; 2 of these groups were uninfected and infected controls, and the 5 remaining groups were all infected and given diet containing antibiotic, amprolium plus ethopabate, antibiotic and amprolium plus ethopabate, clopidol, or antibiotic and clopidol. Chickens in each group were fed respective diet beginning one day prior to coccidia exposure. In two experiments, infection with a coccidiostat-susceptible strain resulted in severe clinical coccidiosis in chickens on the basal ration and on thiopeptin-diet, but dietary thiopeptin prompted recovery of body weight. In one experiment where chickens were infected with a strain resistant to amprolium plus ethopabate and clopidol, birds on dietary thiopeptin attained higher body weight than birds on the basal ration. In three experiments when a strain resistant to amprolium plus ethopabate was inoculated, birds given the basal ration, bacitracin, penicillin, chlortetracycline, or amprolium plus ethopabate diet developed cecal coccidiosis. Chickens on ration containing antibiotic alone attained higher body weight than chickens on the basal ration. Combination of antibiotic and amprolium plus ethopabate resulted in higher weight attained than amprolium plus ethopabate alone. Clopidol suppressed development of coccidiosis, and the combination of antibiotic and clopidol resulted in higher gains than in clopidol alone.