Effect of stress factors on the pathogenesis of necrotic enteritis in broiler chickens

Necrotic enteritis (NE) is described as a disease of high economical impact which affects health and welfare of broilers and may also pose a threat to public health. Therefore any predisposing factor to NE is regarded very important. The effect of stress factors attributed to management practices such as feed deprivation, high stocking density, heat stress, cold stress and vaccination with live attenuated anticoccidial vaccine on the pathogenesis of NE has not been studied adequately. Therefore, the objective of the present study was to validate the effect of the above mentioned management stressors on the pathogenesis of NE by the use of an effective experimental model. For this purpose five experiments were carried out. In each one of the four experiments 240 day old broiler chicks (Cobb 500) were randomly allocated into four experimental groups of 60 broilers each, while in the fifth experiment for the evaluation of vaccination with live attenuated anticoccidial vaccine on the pathogenesis of NE, 300 day old broilers chicken were randomly allocated into five experimental groups of 60 broilers each. Each experimental group consisted of two replicates (subgroups). The experimental period for each experiment was set to 24 days. On day 16, 21, 22, 23 and 24, six birds per subgroup were euthanized. The examinations conducted at each sampling day included the gross lesion scoring of intestine, gizzard and liver, the histopathology of intestine and liver, the flotation of feces, the microscopic examination of wet smears from intestinal mucosa and content, the measurement of pH of intestinal content, the measurement of viscosity of contents of jejunum and ileum, the bacterial cultivation of C. perfringens from liver and swab samples of gizzard, duodenum, jejunum, and ileum and the quantification of C. perfringens in cecum. Moreover, broilers were weighed on day 1, 9, 16, 17 and 21, while feed conversion ratio was calculated for the periods of 10-16 days of age and 17-21 days of age. In order to reproduce the NE, an experimental challenge model using C. perfringens and tenfold dose of a live anticoccidial vaccine was adopted. Experimentally challenged birds were orally infected three times per day with 4x108 cfu C. perfringens for four consecutive days (days 17, 18 19 and 20). The used strain was resistant to rifampicin. For the induction of NE, at day 18 birds were also inoculated orally with tenfold dose of a live anticoccidial vaccine (Paracox TM-5) which consisted of oocysts of E. acervulina, E. maxima, E. mitis and E. tenella. Broilers in all groups were fed a specially formulated three phase ratio (starter 1-9d, grower 10-16d and finisher 17-24d), which included large quantities of wheat, rye and soya. In the finisher ration soya was replaced by fishmeal which acted as predisposing factor of NE. The use of antibiotic growth promoters and anticoccidial drugs was avoided. The aim of the first experiment was to investigate the effect of feed deprivation on the pathogenesis of NE in broiler chickens. The treatment groups used in this experiment were group N served as negative control, group SN where feed deprivation was applied, group P where birds were experimentally challenged with C. perfringens and tenfold dose of a live attenuated anticoccidial vaccine and group SP where birds were both experimentally challenged and suffered starvation. In groups where feed deprivation was applied, the feed was withdrawn at days 16, 17, 18 and 19 for 12 hours daily starting from 21:00 to 09:00. The results of the experiment demonstrated that starvation has a significant protective effect against the experimentally induced NE in broilers, by limiting the C. perfringens caeca counts and reducing the severity of the NE lesions. The objective of second experiment was to assess the influence of high stocking density as a predisposing factor in NE in broiler chickens. The treatment groups used in this experiment were control group N where birds were at normal stocking density (15 birds/m2) and not challenged, group DN where birds were raised at 50% increased stocking density from 1st day (30 birds/m2), group P where birds were raised at standard stocking density and challenged with C. perfringens and with tenfold dose of a live attenuated anticoccidial vaccine and group DP where birds were challenged and raised at increased stocking density as described above. The experiment provides evidence that high stocking density increased the frequency and severity of NE. The purpose of third experiment was to investigate the effects of heat stress on the pathogenesis of NE in broiler chickens. The treatment groups used in this experiment were group N served as negative control, group HN where heat stress (35oC) was applied, group P where birds were experimentally challenged with C. perfringens and with tenfold dose of a live attenuated anticoccidial vaccine, and group HP where birds were both experimentally challenged and suffered heat stress. In groups where heat stress was applied, temperature was increased from 25νC (the recommended temperature for broilers at the respective age) to 35νC at days 16, 17, 18, 19 and 20 for 12 hours daily starting from 21:00 to 09:00h. Heat stress predisposes broilers to the manifestation of NE, because it provokes the occurrence of NE lesions in non challenged birds and also caused further increase of the severity of lesions in challenged birds. The objective of fourth experiment was to assess the influence of cold stress on the pathogenesis of NE in broiler chickens. The treatment groups used in this experiment were group N served as negative control, group CN where cold stress (15 oC) was applied, group P where birds were experimentally challenged with C. perfringens and tenfold dose of a live attenuated anticoccidial vaccine and group CP where birds were both experimentally challenged and suffered cold stress as described above. In groups where cold stress was applied, temperature was decreased from 25νC (the recommended temperature for broilers at the respective age) to 15νC at days 17, 18, 19 and 20 for 12 hours daily starting from 9:00 to 21:00. The experiment provides evidence that cold stress increased severity of subclinical NE. The objective of fifth experiment was to assess the influence of live anticoccidial vaccine on the pathogenesis of NE in broiler chickens and to establish a more efficient experimental model for the reproduction of NE. The treatment groups used in this experiment were group N served as negative control, group PN where birds vaccinated at day 1 with live attenuated anticoccidial vaccine, group P where birds were experimentally challenged with C. perfringens and tenfold dose of a live attenuated anticoccidial vaccine, group M where birds were challenged with C. perfringens and E. maxima and group PM where birds vaccinated at day 1 and were challenged with C. perfringens and E. maxima. The study provides evidence that live anticoccidial vaccine decreased the frequency and severity of experimental NE. Furthermore, the challenge of birds with C. perfringens and E. maxima increased the frequency and aggregated the severity of NE lesions compared to challenge with C. perfringens and tenfold dose of a live anticoccidial vaccine. It is evident from our studies that among the management factors in intensive broiler production systems, high stocking density, heat stress and cold stress pose a significant predisposal role for the induction of NE, while feed deprivation and vaccination against coccidiosis act protectively against it

A Case of Infectious Laryngotracheitis in an Organic Broiler Chicken Farm in Greece

Infectious laryngotracheitis is an economically significant viral disease of chickens, that mainly affects the upper respiratory tract, and is present worldwide. This case reports the first outbreak of infectious laryngotracheitis in a four-week-old organic broiler farm and surrounding flocks in Greece, with typical clinical symptoms and lesions, allegedly provoked by a wild strain of infectious laryngotracheitis virus. Our findings contradict the general perception indicating that the disease appears mainly in older birds and that vaccine strains are the primary cause of infectious laryngotracheitis outbreaks in most continents. A recombinant vectored vaccine was administered, supplementary to biosecurity measures, containing the viral spread. The responsible strain was potentially circulating in the area; therefore, an industry-wide holistic approach was applied, including the vaccination of neighboring broilers and breeders with the same vaccine, the rapid molecular diagnosis of the disease, and strict biosecurity protocols. The results of this holistic effort were effective because, following the application of vaccine and management protocols, manifestations of the disease in regional flocks dropped significantly, and there was no recurrence to date. These findings suggest that vaccination protocols should be modified, especially for organic broilers, to include vaccination against infectious laryngotracheitis

The Effect of Whey on Performance, Gut Health and Bone Morphology Parameters in Broiler Chicks

Whey is a highly nutritious byproduct of the cheese industry that can be used effectively in the animal feed industry. However, the use of whey in poultry diets is limited by its high lactose and mineral contents. The objective of the present study was to evaluate the effect of different concentrations of whey in poultry diets on the performance, intestinal microbiota and physico-chemical parameters of the intestinal ecosystem, as well as on the bone morphology and its strength in broiler chicks. One hundred and twenty-eight, day-old, male broiler chicks were randomly allocated into four treatment groups of 32 chicks each. The treatment groups were: group A, which served as negative control and groups B, C and D, supplemented with 1, 2 and 5% of dietary whey, respectively. Performance of the groups was evaluated throughout the experiment. Following necropsies, the gastrointestinal tract from each bird was removed, divided into its anatomical parts and intestinal samples were taken for microbiological analysis and for pH and viscosity measurement as well. Tibiotarsus was also collected for morphometric analysis and strength evaluation. The statistical analysis of the experimental data revealed that the dietary supplementation of 1 and 2% of whey improved significantly (p ≤ 0.05) the body weight, while the addition of 5% of whey reduced significantly (p ≤ 0.05) the body weight. Furthermore, the addition of 1, 2 and 5% of dietary whey increased significantly (p ≤ 0.05) the pH of jejunum digesta and reduced significantly (p ≤ 0.05) the pH of caecum digesta compared to the control group. The addition of 1 and 2% of whey reduced significantly (p ≤ 0.05) the viscosity in the jejunum and ileum digesta, compared to the addition of 5% of whey which reduced significantly (p ≤ 0.05) the viscosity in jejunum digesta but increased significantly (p ≤ 0.05) the viscosity in ileum digesta. Moreover, the addition of 1, 2 and 5% of dietary whey increased significantly (p ≤ 0.05) the caecal counts of Lactobacillus spp. and Lactococcus lactis, while the addition of 5% of whey reduced significantly (p ≤ 0.05) the tibiotarsus length. It can be concluded that the addition of low quantities of whey up to 2% promoted the performance and gut health of birds, while the addition of higher quantities of whey at the level of 5% had a detrimental effect on the performance and tibiotarsus length

First Detection and Identification of FAdV-8b as the Causative Agent of an Outbreak of Inclusion Body Hepatitis in a Commercial Broiler Farm in Greece

Inclusion body hepatitis (IBH) is an economically important disease of chickens, with a worldwide distribution, caused by Fowl Aviadenoviruses (FAdVs). Currently, the increased number of cases, the virulence of the isolate strains, as well as the lack of cross-species protection highlight that detailed in-field data are fundamental for the development of successful control strategies. This case report provides a detailed clinicopathological investigation of an unusual IBH outbreak in a commercial broiler farm in the region of Macedonia, Greece. The farm consisted of 64,000 birds, originated from the same breeder stock and placed in three different houses (Flock A–C). At 20 days of age, a sudden increase in daily mortality was recorded in Flock A. It is worth mentioning that, although all flocks were serologically (indirect ELISA) and molecularly (RT-PCR) positive for FAdV, the mortality rate, attributed to IBH, was much higher in Flock A compared to others. The clinical manifestation included non-specific symptoms such as depression, inappetence, yellowish mucoid diarrhea, and lack of uniformity. At necropsy, typically, enlarged, pale, and friable livers were dominant, while sporadically lesions were recorded in the pancreas, kidneys, skeletal muscles, and lymphoid organs. The histopathological examination of liver samples showed multifocal inflammation, necrosis, and the presence of basophilic/ eosinophilic inclusion bodies in hepatocytes. In addition, the loss of the architecture of pancreatic lobules and the presence of fibrosis and foci of mononuclear cell aggregates were suggestive of chronic pancreatic inflammation. PCR analysis confirmed the presence of FAdV, belonging to species E, serotype FAdV-8b. Performance and financial calculations revealed that IBH increased Feed Conversion Ratio (FCR), feed cost/chick as well as feed cost/kg live weight, whereas the Livability (%) and the European Production Efficiency Factor (EPEF) were decreased in the most severely affected flocks (Flock A). This study is the first report of the detection and identification of FAdV serotypes associated with IBH in commercial broiler flocks in Greece. However, there is still a lack of information about the circulating FAdV serotypes in the country, and therefore epidemiological studies are needed to establish control strategies for IBH

First Detection and Identification of FAdV-8b as the Causative Agent of an Outbreak of Inclusion Body Hepatitis in a Commercial Broiler Farm in Greece

Inclusion body hepatitis (IBH) is an economically important disease of chickens, with a worldwide distribution, caused by Fowl Aviadenoviruses (FAdVs). Currently, the increased number of cases, the virulence of the isolate strains, as well as the lack of cross-species protection highlight that detailed in-field data are fundamental for the development of successful control strategies. This case report provides a detailed clinicopathological investigation of an unusual IBH outbreak in a commercial broiler farm in the region of Macedonia, Greece. The farm consisted of 64,000 birds, originated from the same breeder stock and placed in three different houses (Flock A–C). At 20 days of age, a sudden increase in daily mortality was recorded in Flock A. It is worth mentioning that, although all flocks were serologically (indirect ELISA) and molecularly (RT-PCR) positive for FAdV, the mortality rate, attributed to IBH, was much higher in Flock A compared to others. The clinical manifestation included non-specific symptoms such as depression, inappetence, yellowish mucoid diarrhea, and lack of uniformity. At necropsy, typically, enlarged, pale, and friable livers were dominant, while sporadically lesions were recorded in the pancreas, kidneys, skeletal muscles, and lymphoid organs. The histopathological examination of liver samples showed multifocal inflammation, necrosis, and the presence of basophilic/ eosinophilic inclusion bodies in hepatocytes. In addition, the loss of the architecture of pancreatic lobules and the presence of fibrosis and foci of mononuclear cell aggregates were suggestive of chronic pancreatic inflammation. PCR analysis confirmed the presence of FAdV, belonging to species E, serotype FAdV-8b. Performance and financial calculations revealed that IBH increased Feed Conversion Ratio (FCR), feed cost/chick as well as feed cost/kg live weight, whereas the Livability (%) and the European Production Efficiency Factor (EPEF) were decreased in the most severely affected flocks (Flock A). This study is the first report of the detection and identification of FAdV serotypes associated with IBH in commercial broiler flocks in Greece. However, there is still a lack of information about the circulating FAdV serotypes in the country, and therefore epidemiological studies are needed to establish control strategies for IBH

Levels of Circulating IgM and IgY Natural Antibodies in Broiler Chicks: Association with Genotype and Farming Systems

Naturally occurring antibodies (NAbs), which are major components of innate immunity, exist in circulation under healthy conditions without prior antigenic stimulation and are able to recognize both self- and non-self-constituents. The present study aimed at identifying potential immunological differences between commercial fast- and slow-growth broilers (n = 555) raised in conventional and free-range systems, respectively, through the use of the specificity, isotypes and levels of circulating NAbs. The possible beneficial effect of oregano-based dietary supplementation was also evaluated. To this end, serum IgM and IgY NAbs against self- (actin and DNA) and non-self- antigens (trinitrophenol and lipopolysaccharide) were measured by ELISA and further correlated with genotype, season and performance. Significantly higher levels of IgM NAbs against all antigens were found in slow-growth compared to fast-growth broilers. IgM NAb levels were also significantly increased in dietarily supplemented slow-growth broilers versus those consuming standard feed. Moreover, significantly elevated levels of anti-DNA IgY NAbs were found in fast-growth compared to slow-growth broilers, whereas the opposite was observed for anti-LPS IgY NAbs. Multivariate linear regression analysis confirmed multiple interactions between NAb levels, genotype, season and performance. Overall, serum NAbs have proven to be valuable innovative immunotools in the poultry industry, efficiently differentiating fast-growing versus slow-growing broilers, and dietary supplementation of plant extracts can enhance natural immunity

A long short-term memory deep learning network for the prediction of epileptic seizures using EEG signals

Summarization: The electroencephalogram (EEG) is the most prominent means to study epilepsy and capture changes in electrical brain activity that could declare an imminent seizure. In this work, Long Short-Term Memory (LSTM) networks are introduced in epileptic seizure prediction using EEG signals, expanding the use of deep learning algorithms with convolutional neural networks (CNN). A pre-analysis is initially performed to find the optimal architecture of the LSTM network by testing several modules and layers of memory units. Based on these results, a two-layer LSTM network is selected to evaluate seizure prediction performance using four different lengths of preictal windows, ranging from 15 min to 2 h. The LSTM model exploits a wide range of features extracted prior to classification, including time and frequency domain features, between EEG channels cross-correlation and graph theoretic features. The evaluation is performed using long-term EEG recordings from the open CHB-MIT Scalp EEG database, suggest that the proposed methodology is able to predict all 185 seizures, providing high rates of seizure prediction sensitivity and low false prediction rates (FPR) of 0.11–0.02 false alarms per hour, depending on the duration of the preictal window. The proposed LSTM-based methodology delivers a significant increase in seizure prediction performance compared to both traditional machine learning techniques and convolutional neural networks that have been previously evaluated in the literature.Presented on: Computers in Biology and Medicin

Discrimination of preictal and interictal brain states from long-term EEG data

Summarization: The discrimination of the preictal state in EEG signals is of great importance in neuroscience and the epileptic seizure prediction field has yet to provide conclusive evidence. In this study, three different classification approaches, including the Repeated Incremental Pruning to Produce Error Reduction (RIPPER) algorithm, Support Vector Machines (SVMs) and Neural Networks (NNs), are investigated for their ability to discriminate preictal from interictal EEG segments. Using public EEG data, a wide range of features is extracted from each segment and then applied to the classifiers. The analysis covers a patient-specific approach, so as to optimize the decision to each patient individually and a patient-independent approach in order to explore a global prediction approach that can discriminate randomly selected preictal and interictal segments from all patients. Overall, the first approach aims at revealing patient-specific epileptic characteristics, whereas the second seeks for potential general preictal-related signs. The results reveal that in the patient-specific case, the SVM classifier exhibits the highest classification accuracy in both preictal and interictal classes reaching 85.75% sensitivity and specificity. As it is expected, the classification performance is lower for the patient-independent case at 68.5%, due to the complicated nature of preictal activity and the variations among patients condition.Παρουσιάστηκε στο: 30th IEEE International Symposium on Computer-Based Medical System