The influence of diet on necrotic enteritis in broiler chickens.

Necrotic enteritis was reproduced in broiler chickens by mixing cultures of Clostridium perfringens in the feed. Mortality due to necrotic enteritis was higher among chickens fed rations based on wheat, rye, barley, and oat groats than among chickens fed corn-based rations. Addition of pentosanase to a wheat-based diet did not affect the level of mortality due to necrotic enteritis. Addition of pectin and guar gum to different rations severely reduced growth rate and eliminated necrotic enteritis from test birds. Addition of glucose to a corn-based diet caused a small increase in mortality due to necrotic enteritis.     

Comparative effect of dietary supplements on the performance and severity of experimental Eimeria tenella infection in broiler chickens

Tropical Animal Health and Production - This study evaluated the productive and reproductive performance of Charolais cows with different body mass index (BMI) at calving and the development of...     

Optimized necrotic enteritis model producing clinical and subclinical infection of Clostridium perfringens in broiler chickens

In this study we assessed the roles of Eimeria infection and dietary manipulation (feeding a diet with a high level of fishmeal) in an Australian necrotic enteritis (NE) challenge model in broiler chickens. An experiment was designed to test the hypothesis that Eimeria infection and dietary manipulation, i.e., inclusion of fishmeal in the diet, are necessary to induce NE experimentally. The results showed that the combination of Eimeria administration and fishmeal feeding had a significant effect on induction of clinical and subclinical Clostridium perfringens infection. The majority of the mortality that occurred during the second week of the trial was due to an NE outbreak following the C. perfringens challenge. The mortality rate of the birds was 12.00% for the high-fishmeal (HFM; 500 g/kg) group and 9.33% for the low-fishmeal (LFM; 250 g/kg) group when the birds were subjected to C. perfringens and Eimeria. Fishmeal alone did not induce significant mortality in birds challenged only with C. perfringens but showed a significantly higher C. perfringens count than the non-fishmeal (NFM) control group. Eimeria administration had a significant effect on NE-related mortality but did not have an effect on the C. perfringens count. In accordance with the time course of bird mortality, it can be determined that of the 3 successive days of oral gavage with C. perfringens, the first inoculation was essential for inducing NE, but the third had no additional effect on NE-related mortality. Also, reducing the fishmeal level from 500 to 250 g/kg had no negative impact on the reproducibility of the model. It may be concluded that NE can be consistently induced under experimental conditions by feeding broilers a diet containing 250 g/kg fishmeal, using a single inoculation with low numbers of Eimeria, administering one or two oral C. perfringens inoculations, and maintaining appropriate ambient temperatures and diets.     

Live attenuated vaccine-based control of necrotic enteritis of broiler chickens

A vaccine for necrotic enteritis (NE) of chickens would reduce the current need to prevent or treat the disease in broiler chickens with antimicrobial drugs. The objective of this study was to understand aspects of immunity to the disease. The first experiment examined the virulence of six strains of Clostridium perfringens isolated from cases of NE in broiler chickens. Using a 5-day experimental oral infection of 2-week-old broiler chickens, four of the six strains were found to be virulent. Pulsed-field gel electrophoresis and PCR showed that virulence was not associated with a plasmid encoding the beta2 toxin gene, cpb2, since this was present in virulent and one of the two avirulent strains. In the second experiment, two virulent and one avirulent strains were tested for their ability to immunize ("infection-immunization") chickens through the oral route. The procedure used experimental infection for 5 days followed by bacitracin treatment for 9 days, and then re-challenge 2 days later with a virulent strain, CP4. Infection-immunization with the virulent isolates protected chickens from subsequent virulent challenge, whereas the infection-immunization with the avirulent isolate did not. In a third experiment, two of four alpha-toxin-negative mutants of CP4 protected birds from experimental NE after oral immunization. These two mutants were also attenuated for virulence. We conclude that it is possible to immunize chickens successfully against NE and that immunogen(s) other than alpha-toxin are important in protective immunity against oral infection.     

Perturbations of the ileal mycobiota by necrotic enteritis in broiler chickensOA

Background: Intestinal microbiota is critical for maintaining animal health and homeostasis. However, involvement of the fungal community, also known as the mycobiota, in animal health and disease is poorly understood. This study was aimed to examine the association between the intestinal mycobiota and the severity of necrotic enteritis(NE), an economically significant poultry disease.Methods: A total of 90 day-of-hatch Cobb broilers were infected with Eimeria maxima on d 10, followed by an oral...     

Efficacy of narasin in the prevention of necrotic enteritis in broiler chickens

The efficacy of narasin in the control of necrotic enteritis (NE) was investigated in a floor pen study of 2000 broiler chickens using a Clostridium perfringens feed inoculum challenge model. Treatments were 1) nonmedicated, nonchallenged; 2) nonmedicated, challenged; 3) narasin, nonchallenged; 4) narasin, challenged. Narasin was administered at 70 ppm in the feed from day 0 to trial termination on day 41. Challenge inoculum contained approximately 1 x 10(8) colony-forming units CP/ml and was administered from day 14 to day 16. In the unmedicated groups, challenged birds had significantly (P < 0.05) lower mean body weight and reduced feed efficiency at day 21 and significantly (P < 0.01) higher cumulative NE mortality at day 41 compared with unchallenged. Similarly, among unmedicated birds, those challenged had a significantly (P < 0.01) higher mean NE score on day 17 and significantly (P < 0.05) higher mean huddling scores on days 15-17 than unchallenged. Among challenged birds, those fed narasin had significantly (P < 0.05) higher mean body weight and improved feed efficiency at days 21 and 41 and significantly (P < 0.01) lower cumulative NE mortality at day 41 than unmedicated. Similarly, among challenged birds, those receiving narasin had a lower mean NE score on day 17 (P > 0.05) and significantly (P < 0.05) lower huddling scores on days 16 and 17 than unmedicated. Coccidiosis lesion scores were zero for birds euthanatized from all treatment groups on day 17, suggesting that the beneficial effects of narasin were not due to prevention of coccidiosis. This study thus provides evidence that narasin is effective in the prevention of necrotic enteritis in broiler chickens.     

The successful experimental induction of necrotic enteritis in chickens by Clostridium perfringens: a critical review

Necrotic enteritis (NE) is one of the most important enteric diseases in poultry and is a high cost to the industry worldwide. It is caused by avian-specific, Necrotic Enteritis Beta toxin (NetB)-producing, strains of Clostridium perfringens that also possess in common other virulence-associated genes. In Europe the disease incidence has increased since the ban on in-feed “growth promoting” antibiotics. Because of this, many recent studies of NE have focused on finding different ways to control the disease, and on understanding its pathogenesis. Frustratingly, reproduction of the disease has proven impossible for some researchers. This review describes and discusses factors known to be important in reproducing the disease experimentally, as well as other considerations in reproducing the disease. The critical bacterial factor is the use of virulent, netB-positive, strains; virulence can be enhanced by using tpeL- positive strains and by the use of young rather than old broth cultures to increase toxin expression. Intestinal damaging factors, notably the use of concurrent or preceding coccidial infection, or administration of coccidial vaccines, combined with netB-positive C. perfringens administration, can also be used to induce NE. Nutritional factors, particularly feeding high percentage of cereals containing non-starch polysaccharides (NSP) (wheat, rye, and barley) enhance disease by increasing digesta viscosity, mucus production and bacterial growth. Animal proteins, especially fish meal, enhance C. perfringens proliferation and toxin production. Other factors are discussed that may affect outcome but for which evidence of their importance is lacking. The review compares the different challenge approaches; depending on the aim of particular studies, the different critical factors can be adjusted to affect the severity of the lesions induced. A standardized scoring system is proposed for international adoption based on gross rather than histopathological lesions; if universally adopted this will allow better comparison between studies done by different researchers. Also a scoring system is provided to assist decisions on humane euthanasia of sick birds.     

影响鸡坏死性肠炎病例复制的关键因素

坏死性肠炎(necrotic enteritis,NE)是家禽中最重要的肠道疫病之一,呈世界性流行,严重危害养鸡业发展。人工复制鸡坏死性肠炎病例是研究该病发病机制及筛选有效药物的重要手段,然而在实际试验过程中,通常受实验动物、感染菌株、诱导病原等多方面因素影响而难以成功复制病例。鉴于此,现综述了影响鸡坏死性肠炎病例成功复制的关键因素,包括攻毒使用的实验动物、菌株毒素、菌株培养条件、诱导病因等,同时探讨了如何通过调整这些因素来改善人工复制鸡坏死性肠炎病例的严重程度,分析了鸡坏死性肠炎病例的病变评分系统,以期为鸡坏死性肠炎的实验室研究及综合防控提供理论基础。     

Eimeria brunetti and Eimeria necatrix in chickens of Argentina and confirmation of seven species of Eimeria

Ten poultry farms (broiler breeder pullets, layer pullets, and broilers) in the provinces of Entre Rios and Buenos Aires in Argentina were examined for presence of Eimeria spp. Litter samples obtained from flocks 7-11 wk old were taken to the laboratory for oocyst counting and sporulation, then concentrated for inoculation into coccidia-free chickens. Species were identified by prepatent period, oocyst size, location and appearance of lesions in the intestine, microscopic examination of mucosal smears, and histology (to confirm Eimeria brunetti). On this basis, Eimeria praecox was found in two samples, Eimeria mitis in two, Eimeria acervulina in nine, Eimeria maxima in seven, Eimeria necatrix in three, Eimeria tenella in seven, and E. brunetti in four. These results confirm the presence of all seven recognized species of Eimeria in chickens in the Republic of Argentina.     

Towards the control of necrotic enteritis in broiler chickens with in-feed antibiotics phasing-out worldwide

Poultry production has undergone a substantial increase compared to the livestock industries since 1970.However, the industry worldwide is now facing challenges with the removal of in-feed antibiotics completely or gradually, as the once well-controlled poultry diseases have re-emerged to cause tremendous loss of production. Necrotic enteritis(NE) is one of the most important diseases which costs the industry over two billion dollars annually. In this paper, we review the progress on the etiology of NE and its control through dietary modifications, pre-and probiotics, short chain fatty acids, and vaccination. The other likely measures resulted in the most advances in the toxin characterization are also discussed. Vaccine strategies may have greater potential for the control of NE mainly due to clearer etiology of NE having been elucidated in recent years with the identification of necrotic enteritis toxin B-like(NetB) toxin. Therefore, the use of alternatives to in-feed antibiotics with a better understanding of the relationship between nutrition and NE, and limiting exposure to infectious agents through biosecurity and vaccination, might be a tool to reduce the incidence of NE and to improve gut health in the absence of in-feed antibiotics. More importantly, the combinations of different measures may achieve greater protection of birds against the disease. Among all the alternatives investigated, prebiotics, organic acids and vaccination have shown improved gastrointestinal health and thus, have potential for the control of NE.     

Molecular detection and characterization of Clostridium perfringens toxin genes causing necrotic enteritis in broiler chickens

Tropical Animal Health and Production - A total of 464 samples comprising of cloacal swabs from necrotic enteritis suspected live birds (191), intestinal scrapings from dead birds with symptoms of...     

Fumonisins affect the intestinal microbial homeostasis in broiler chickens,predisposing to necrotic enteritis

Fumonisins (FBs) are mycotoxins produced by Fusarium fungi. This study aimed to investigate the effect of these feed contaminants on the intestinal morphology and microbiota composition, and to evaluate whether FBs predispose broilers to necrotic enteritis. One-day-old broiler chicks were divided into a group fed a control diet, and a group fed a FBs contaminated diet (18.6 mg FB1+FB2/kg feed). A significant increase in the plasma sphinganine/sphingosine ratio in the FBs-treated group (0.21 ± 0.016) compared to the control (0.14 ± 0.014) indicated disturbance of the sphingolipid biosynthesis. Furthermore, villus height and crypt depth of the ileum was significantly reduced by FBs. Denaturing gradient gel electrophoresis showed a shift in the microbiota composition in the ileum in the FBs group compared to the control. A reduced presence of low-GC containing operational taxonomic units in ileal digesta of birds exposed to FBs was demonstrated, and identified as a reduced abundance of Candidatus Savagella and Lactobaccilus spp. Quantification of total Clostridium perfringens in these ileal samples, previous to experimental infection, using cpa gene (alpha toxin) quantification by qPCR showed an increase in C. perfringens in chickens fed a FBs contaminated diet compared to control (7.5 ± 0.30 versus 6.3 ± 0.24 log10 copies/g intestinal content). After C. perfringens challenge, a higher percentage of birds developed subclinical necrotic enteritis in the group fed a FBs contaminated diet as compared to the control (44.9 ± 2.22% versus 29.8 ± 5.46%).

Electronic supplementary material

The online version of this article (doi:10.1186/s13567-015-0234-8) contains supplementary material, which is available to authorized users.     

Interaction of aflatoxin with Eimeria tenella infection and monensin in young broiler chickens.

Young broiler chicks inoculated with Eimeria tenella and given a diet containing 2.5 mug aflatoxin/g had significantly higher mortality than birds with aflatoxicosis or coccidiosis alone or uninoculated controls. This effect was seen even when a light coccidial infection alone did not increase mortality or cause weight depression. In addition this higher mortality with the combination began earleir and occurred at a higher rate than did mortality from aflatoxin or cecal coccidiosis alone. Dietary monensin sodium (99 umg/g) did not completely prevent mortality and weight depression when aflatoxin and E. tenella were in combination. Aflatoxin and E. tenella singly significantly depressed three-week body weights; however, the depression was most severe when the two were in combination. Both dietary aflatoxin and E. tenella significantly reduced hemoglobin, packed cell volume, and plasma pigmentation, and in combination resulted in more severely reduced hemoglobin, packed cell volume, and plasma pigmentation. Coccidial lesion scores were significantly less for the combination of E. tenella and aflatoxicosis than for coccidiosis alone. This atypical response of the ceca to E. tenella in the presence of dietary aflatoxin was characterized by less distended ceca, very little coagulated blood in the ceca, and apparently more profuse cecal hemorrhage.     

Effects of Bacillus coagulans supplementation on the growth performance and gut health of broiler chickens with Clostridium perfringens-induced necrotic enteritis

Background: The poultry industry is in need of effective antibiotic alternatives to control outbreaks of necrotic enteritis(NE) due to Clostridium perfringens.Methods: This study was conducted to investigate the effects of feeding Bacil us coagulans on the growth performance and gut health of broiler chickens with C. perfringens-induced NE. Two hundred and forty 1-day-old broiler chicks were randomly assigned to a 2 × 2 factorial arrangement with two dietary B. coagulans levels(0 or 4 × 109 CFU/kg of diet) and two disease chal enge statuses(control or NE chal enged).Results: NE-induced reduction in body weight gain was relieved by the addition of B. coagulans into broiler diets compared with the NE-infected birds. NE infection damaged intestinal morphological structure, promoted intestinal C.perfringens growth and liver invasion, and enhanced anti-C. perfringens specific sI gA concentrations in the gut and specific IgG levels in serum compared with the uninfected birds. NE infection significantly(P 0.05) decreased mucin-2(at 14 d post-infection(DPI), tol-like receptor 2(TLR2, at 7 and 14 DPI), TLR4(at 7 and 14 DPI), tumor necrosis factor super family15(TNFSF15, at 7 and 14 DPI), lysozyme(LYZ, at 14 DPI) and fowlicidin-2(at 7 and 14 DPI) mR NA levels, whereas it dramatical y(P = 0.001) increased IFN-γ mR NA levels at 7 DPI. However, chal enged birds fed diets supplemented with B.coagulans showed a significant(P 0.01) decrease in gut lesion scores, decreased C. perfringens numbers in the cecum and liver, and an increase in fowlicidin-2 mR NA levels in compared with the uninfected birds. In addition, compared with the non-supplemented group, dietary inclusion of B. coagulans improved intestinal barrier structure, further increased specific sI gA levels and alkaline phosphatase(IAP) activity in the jejunum, enhanced the expression of jejunum lysozyme mR NA, and inhibited the growth, colonization, and invasion of C. perfringens; in contrast, it reduced serum-specific IgG concentrations and jejunum IFN-γ mR NA levels.Conclusion: These results indicated that dietary B. coagulans supplementation appeared to be effective in preventing the occurrence and reducing the severity of C. perfringens-induced NE in broiler chickens.     

Influence of reticuloendotheliosis on the severity of Eimeria tenella infection in broiler chickens

Broiler chickens free of maternal immunity to reticuloendotheliosis virus (REV) were used in the experiment. Two groups of 25 chickens were inoculated with REV at one day of age. One of these groups and another group of 25 chickens were inoculated with Eimeria tenella sporulated oocysts at 7 days of age. Chickens inoculated with E. tenella showed bloody diarrhoea from 12 to 14 days of age. Six out of 25 chickens died (P less than 0.05) at 13 and 14 days of age in the dual infected group. At 14 days of age, when chickens were killed, the lesion score in the combined infection group, was statistically different from that in the chickens inoculated with E. tenella alone. Also the weights of the bursa of Fabricius and thymus were lower in the two REV infected groups than in the controls. Although REV infection alone adversely affected the weight gain and feed conversion, with combined infection this effect was much greater. Following REV inoculation most of the chickens showed feathering defects and all the examined chickens were viraemic at 21 days of age. At the same age, all but one chicken failed to show precipitating antigenaemia and about one-half of these chickens showed a very low serum neutralisation titre. None of these chickens showed precipitating antibodies.     

一起杂交肉鸡坏死性肠炎的诊治体会

8月份以来,我省平原县某地饲养的杂交肉食鸡出现了以饲料消化不良、粪便变稀、变绿、略带红色或桔红色等特征的疾病,当作大肠杆菌病、球虫病进行治疗,效果较差。后来笔者经过临床剖检及实验室诊断,确定为魏氏梭菌引起的肉鸡坏死性肠炎。现将其诊治过程报道如下。1发病情况山东省平原县的几处养鸡场(户),共发病肉杂鸡9500只,日龄6～20d左右。发病5d内共死亡350只左右,死亡率3.68%。使用环丙沙星、庆大霉素、痢特灵等治疗效果不佳。2临床症状及剖检变化病鸡表现为打喷嚏、甩头、流涕、呼噜,眼睑肿胀,排红色或桔红色粪便,呈现水样腹泻,精神沉郁…