An exploratory study on the prevalence of neoplasms in two strains of laying hens during an extended production cycle.

There is a trend towards extended periods of lay in the laying hen industry. Extended cycles without a moulting stage gives the opportunity to obtain more eggs from a single hen. However, appropriate management and care for older laying hens is needed. In this trial we assessed the prevalence of conditions in old laying hens with a focus on neoplastic diseases. In total 150 ISA Brown and 150 Dekalb white laying hens were selected at 86 weeks of age. Of each hen line, 75 hens were necropsied at 86 weeks of age; the other half were monitored for 44 weeks after which they were necropsied. At week 86, 15.3% of the hens suffered from a neoplasm, ISA Brown being the most affected. During the follow up period, 50 birds died because of a natural cause of which 20 hens showed signs of a neoplasms. At the end of the follow up period, 43% of the hens were affected by a neoplasm. Adenocarcinoma was the most prevalent neoplasm and equally distributed among both hen lines. Leiomyomas were most frequently observed in ISA brown hens. Among causes of death, 19.05% of ISA brown and 20.69% of Dekalb White was attributed to a neoplasm. Furthermore, link with ovarian activity and other pathologies were made with significant correlations between adenocarcinomas and inactive ovaries. In conclusion, this study shows that the prevalence of adenocarcinoma and leiomyoma is a factor to be considered in longer laying cycles with 1/5th of the mortality caused by these processes.RESEARCH HIGHLIGHTSAt 86 weeks of age, the prevalence of neoplasms was 15.3%, mainly in brown hens.At 130 weeks of age, 43% of the hens were affected by a neoplasm.Adenocarcinoma was the most prevalent neoplasm equally distributed among hen lines.Leiomyoma was the second most prevalent neoplasm, mainly found in brown hens.

A case of clubbed down syndrome in broilers.

This study presents a case of clubbed down syndrome in conventional broilers. During the first week of life, severe growth retardation was observed in approximately 25% of the flock. The growth-retarded chicks weighed only 45 g and showed a typical feather disorder which was most apparent on their abdomen and was defined in literature as typical for clubbed down syndrome. Necropsies, histology, biochemical analysis of blood and liver samples, serology and different PCR tests were performed in broilers to assess the aetiology of the clinical signs that were present in the affected broiler farm. Because of the suspicion of a possible link with the broiler-breeder farms, different investigations including serology, PCR and feed analysis were also performed on these farms. The results suggest that an accidentally excessive amount of calcium and iron in the feed of broiler-breeders, 3 weeks prior to first clinical signs in broilers, led to the development of clubbed down in the offspring, because of a relative Zn-deficiency in broiler-breeders and an absolute Zn-deficiency in the hatching eggs that were produced during this period. This appeared to be a reversible process as no clinical signs were observed in younger offspring of these broiler-breeders after they had consumed more of the new batch of feed. A potential involvement of Astrovirus could not be completely ruled out. This study demonstrates the importance of correct mineral concentrations in broiler-breeder feed and the impact it can have on the development of the offspring.

Isolation of Burkholderia pseudomallei from a Pet Green Iguana, Belgium.

We isolated Burkholderia pseudomallei, the causative agent of melioidosis, from liver granulomas of a pet green iguana (Iguana iguana) in Belgium. This case highlights a risk for imported green iguanas acting as a reservoir for introduction of this high-threat, zoonotic pathogen into nonendemic regions.

Efficacy of gamithromycin against Ornithobacterium rhinotracheale in turkey poults pre-infected with avian metapneumovirus.

Ornithobacterium rhinotracheale is an avian respiratory pathogen that affects turkeys. The objective of this study was to evaluate the clinical efficacy of gamithromycin (GAM) against O. rhinotracheale in turkeys. The birds were inoculated oculonasally with 10(8) colony-forming units (cfu) of O. rhinotracheale, preceded by infection with avian metapneumovirus. In addition to a negative (CONTR-) and a positive control group (CONTR+) there were two treated groups administered GAM (6 mg/kg) either subcutaneously (GAM SC) or orally (GAM PO) by administration as a single bolus at one-day post-bacterial infection (p.b.i.). From the start of the avian metapneumovirus infection until the end of the experiment, the turkeys were examined clinically and scored daily. In addition, tracheal swabs were collected at several days p.b.i. Necropsy was performed at 4, 8 and 12 days p.b.i. to evaluate the presence of gross lesions, and to collect trachea and lung tissue samples and air sac swabs for O. rhinotracheale quantification. The clinical score of the GAM SC group showed slightly lower values and birds recovered earlier than those in the GAM PO and CONTR+ groups. O. rhinotracheale cfus were significantly reduced in tracheal swabs of the SC group between 2 and 4 days p.b.i. At necropsy, CONTR+ showed higher O. rhinotracheale cfu in lung tissues compared to the treated groups. Moreover, at 8 days p.b.i. only the lung samples of CONTR+ were positive. In conclusion, the efficacy of GAM against O. rhinotracheale was demonstrated, especially in the lung tissue. However, the PO bolus administration of the commercially available product was not as efficacious as the SC bolus.

Marek's disease virus associated ocular lymphoma in Roulroul partridges (Rollulus rouloul).

Two 1-year old Roulroul partridges (Rollulus rouloul), one male and one female, were presented because of eye problems and anorexia. Twenty of the 30 Roulroul partridges in the owner's collection had already died. The affected birds stopped eating, became thinner, and eventually died. Antibiotic treatment, which started because of the suspicion of a septicaemic process, was unsuccessful. At clinical examination of the two partridges it was found that in both birds, one eye ball was filled with a whitish yellow amorphous material and the other eye ball of the female showed a distinct corneal opacity. Both presented birds were euthanized. Necropsy revealed no significant abnormalities in addition to the eye lesions. Histology and immunohistochemistry of the female's eye revealed an infiltrate of T-lymphocytes corresponding to ocular lymphoma. Herpesvirus genus-specific PCR, followed by Sanger sequencing confirmed the presumptive diagnosis of Marek's disease in both birds. To our knowledge, this is the first confirmed case of infection with Gallid Herpesvirus 2 (Marek's disease virus) in partridges and the first case in this specific species.

Mycoplasma columbinum Isolated From a Racing Pigeon ( Columba livia ) With Arthritis.

A juvenile racing pigeon ( Columba livia ) was presented with drooping of the wing and inability to fly. On physical examination, the right shoulder joint was swollen. The pigeon was euthanatized and submitted for necropsy. An excessive amount of fibrin was present in the canalis triosseus with severe arthritis of the affected shoulder joint. A pure growth of Mycoplasma-like colonies was obtained on microbiological culture of the shoulder joint. A 16S ribosomal RNA gene-specific polymerase chain reaction assay was performed on the isolate and revealed 100% similarity with Mycoplasma columbinum . Although infectious arthritis in homing pigeons is primarily associated with paratyphoid and Streptococcus gallolyticus infection, clinical practitioners should consider the potential role of Mycoplasma columbinum in arthritis in pigeons.

Role of Maternal Antibodies in the Protection of Broiler Chicks against Campylobacter Colonization in the First Weeks of Life.

Thermophilic Campylobacter species are the most common cause of bacterium-mediated diarrheal disease in humans globally. Poultry is considered the most important reservoir of human campylobacteriosis, but so far, no effective countermeasures are in place to prevent the bacterium from colonizing broiler flocks. This study investigated maternal antibodies' potential to offer protection against Campylobacter in broiler chicks via a field trial and an immunization trial. In the field trial, breeder flocks with high and low anti-Campylobacter antibody levels in the yolk were selected based on serological screening. Offspring were subsequently monitored for maternal antibodies and Campylobacter prevalence during early life. Although maternal antibodies declined rapidly in the serum of broilers, offspring from flocks with lower anti-Campylobacter antibody levels seemed to be more susceptible to colonization. In the immunization trial, breeders from a seropositive breeder flock were vaccinated with an experimental bacterin or subunit vaccine. Immunization increased antibody levels in the yolk and consequently in the offspring. Elevated maternal antibody levels were significantly associated with reduced Campylobacter susceptibility in broilers at 2 weeks old but not at 1 and 3 weeks old. Overall, the protective effect of maternal immunity should be cautiously considered in the context of Campylobacter control in broilers. Immunization of breeders may enhance resistance but is not a comprehensive solution.

Clinical efficacy of florfenicol administered in the drinking water against Ornithobacterium rhinotracheale in turkeys housed in different environmental conditions: a pharmacokinetic/pharmacodynamic approach.

In poultry rearing, medicated drinking water is a commonly used administration route, but drug uptake can be affected by many factors. In this study, the influence of two important parameters, the photoperiod and feeding schemes, on florfenicol uptake in turkeys was tested. First, the uptake was determined as the pharmacokinetic/pharmacodynamic profile of florfenicol; and second, we evaluated the clinical efficacy of florfenicol against Ornithobacterium rhinotracheale. Both experiments were conducted during a 5-day treatment of 30 mg/kg body weight florfenicol administered via drinking water and considering different photoperiods and feeding schemes (group 20/4L: photoperiod of 20 h, fed ad libitum; group 16/8L: photoperiod of 16 h, fed ad libitum; group 16/8R: photoperiod of 16 h, fed ad libitum but feed was withdrawn during the dark period and replaced 1 h after lighting). On day 1 of treatment, all groups showed plasma concentrations above the minimum inhibitory concentration (both MIC50 and MIC90, 1 mg/l) of 37.7%, 63.5% and 53.1% of a 24-h interval for 20/4L, 16/8L and 16/8R, respectively. Only in the 16/8L and 16/8R groups was the MIC also exceeded on day 5 (47.9% and 21.5% of a 24-h interval, respectively). In all groups, a clinical improvement could be noticed, resulting in reduction of the clinical score. However, only the 16/8L and 16/8R groups showed significant differences from the control group. The results demonstrated an important influence of the photoperiod on the pharmacokinetics of florfenicol as well as the clinical outcome in an infection model. It can be advised that the photoperiod should be <20 h to have sufficient drug intake. Nevertheless, there was no effect between fed and fasted turkeys for both the pharmacokinetics and the clinical outcome.

Evaluation of a self-amplifying mRNA reporter vaccine in explant models of broiler chickens.

In order to minimize animal loss and economical loss, industrial poultry is heavily vaccinated against infectious agents. mRNA vaccination is an effective vaccination platform, yet little to no comprehensive, comparative studies in avians can be found. Nevertheless, poultry mRNA vaccination could prove to be very interesting due to the relatively low production cost, especially true when using self-amplifying mRNA (saRNA), and their extreme adaptability to new pathogens. The latter could be particularly useful when new pathogens join the stage or new variants arise. As a first step toward the investigation of saRNA vaccines in poultry, this study evaluates a luciferase-encoding saRNA in avian tracheal explants, conjunctival explants, primary chicken cecal cells and 18-day embryonated eggs. Naked saRNA in combination with RNase inhibitor and 2 different lipid-based formulations, that is, ionizable lipid nanoparticles (LNPs) and Lipofectamine Messenger Max, were evaluated. The saRNA-LNP formulation led to the highest bioluminescent signal in the tracheal explants, conjunctival explants and cecal cell cultures. A dose-response experiment with these saRNA-LNPs (33-900 ng/well) in these avian organoids and cells showed a nonlinear dose-response relationship. After in ovo administration, the highest dose of the saRNA-LNPs (5 µg) resulted in a visual expression as a weak bioluminescence signal could be seen. The other delivery approaches did not lead to a visual saRNA expression in the embryos. In conclusion, effective entry of saRNA encapsulated in LNPs followed by successful saRNA translation in poultry was established. Hence, mRNA vaccination in poultry could be possible, but further in vivo testing is needed.

Reducing Campylobacter colonization in broilers by active immunization of naive broiler breeders using a bacterin and subunit vaccine.

Campylobacter is the main cause of human gastroenteritis worldwide, with 50 to 80% of the cases related to consumption of poultry products. Maternal antibodies (MAB) from commercial breeder flocks may protect their progeny against infection during the first few weeks of life. We here studied the prevalence of Campylobacter antibody titers in broiler breeder flocks and to which extent immunization of broiler breeders increases maternal anti-Campylobacter titers in their progeny and protects the offspring against Campylobacter colonization. Two vaccines were used: a bacterin mix of 13 Campylobacter strains and a subunit vaccine comprising 6 immunodominant Campylobacter antigens. All sampled on-farm breeder flocks were positive for anti-Campylobacter antibodies, yet in some breeder flocks only very low titers were detected. Vaccination of SPF broiler breeder flocks with both subunit and bacterin vaccines resulted in a prolonged presence of anti-Campylobacter antibodies in the serum and intestinal mucus of chicks. These bacterin- or subunit vaccine-induced MAB conferred protection against Campylobacter colonization in chicks until 7 and 21 d of age, respectively, but only at a low challenge dose (102.5 cfu). The concentration of MAB in the mucus is probably too low to sufficiently capture Campylobacter when higher challenge doses are used. In conclusion, vaccinating broiler breeders protects their offspring against Campylobacter colonization under low pathogen exposure conditions.

Occurrence of viable Brachyspira spp. on carcasses of spent laying hens from supermarkets.

Brachyspira spp. are frequent inhabitants of the chicken's intestine and some have been associated with enteric disease in humans. We studied contamination with Brachyspira spp. of carcasses of spent laying hens as a possible source of infections for humans and animals that may eat this meat. Eleven batches of hen carcasses, for a total of 110 carcasses, were bought in Belgian supermarkets during 2009-2010. Carcass rinse samples were examined for the presence of Brachyspira. Brachyspira spp. were cultured from some carcass in all batches. Besides presumably non-pathogenic species such as Brachyspira murdochii and Brachyspira innocens, the poultry pathogen Brachyspira intermedia and the poultry and suspected human pathogen Brachyspira pilosicoli were identified in 7/11 and 1/11 carcass batches, respectively, at high numbers, as shown using quantitative polymerase chain reactions. Multilocus sequence typing (MLST) demonstrated the presence of 2 and 13 MLST types of B. pilosicoli and B. intermedia, respectively, with all strains belonging to novel MLST types. The findings show that carcasses of spent laying hens are commonly contaminated with high numbers of Brachyspira spp., including the suspected zoonotic agent B. pilosicoli.

Dose-dependent impact of enrofloxacin on broiler chicken gut resistome is mitigated by synbiotic application.

Fluoroquinolone agents are considered critical for human medicine by the World Health Organization (WHO). However, they are often used for the treatment of avian colibacillosis in poultry production, creating considerable concern regarding the potential spread of fluoroquinolone resistance genes from commensals to pathogens. Therefore, there is a need to understand the impact of fluoroquinolone application on the reservoir of ARGs in poultry gut and devise means to circumvent potential resistome expansion. Building upon a recent dose optimization effort, we used shotgun metagenomics to investigate the time-course change in the cecal microbiome and resistome of broiler chickens receiving an optimized dosage [12.5 mg/kg body weight (bw)/day], with or without synbiotic supplementation (PoultryStar®, BIOMIN GmbH), and a high dosage of enrofloxacin (50 mg/kg bw/day). Compared to the high dose treatment, the low (optimized) dose of enrofloxacin caused the most significant perturbations in the cecal microbiota and resistome of the broiler chickens, demonstrated by a lower cecal microbiota diversity while substantially increasing the antibiotic resistance genes (ARGs) resistome diversity. Withdrawal of antibiotics resulted in a pronounced reduction in ARG diversity. Chickens receiving the synbiotic treatment had the lowest diversity and number of enriched ARGs, suggesting an alleviating impact on the burden of the gut resistome. Some Proteobacteria were significantly increased in the cecal metagenome of chickens receiving enrofloxacin and showed a positive association with increased ARG burden. Differential abundance (DA) analysis revealed a significant increase in the abundance of ARGs encoding resistance to macrolides-lincosamides-streptogramins (MLS), aminoglycosides, and tetracyclines over the period of enrofloxacin application, with the optimized dosage application resulting in a twofold higher number of affected ARG compared to high dosage application. Our results provide novel insights into the dose-dependent effects of clinically important enrofloxacin application in shaping the broiler gut resistome, which was mitigated by a synbiotic application. The contribution to ameliorating the adverse effects of antimicrobial agents, that is, lowering the spread of antimicrobial resistance genes, on the poultry and potentially other livestock gastrointestinal microbiomes and resistomes merits further study.

Broiler Chicken Behavior and Activity Are Affected by Novel Flooring Treatments.

The objective was to determine broiler chicken behavioral differences in response to novel flooring treatments. Broilers (n = 182) were housed in 14 pens (a random subset from a larger-scale study including 42 pens), with 13 birds/pen. One of seven flooring treatments were randomly allocated to 14 pens (2 pens per treatment). The flooring treatments (provided from day 1 {1} or day 29 {29}) included regularly replaced shavings (POS), a mat with 1% povidone-iodine solution (MAT), and the iodine mat placed on a partially slatted floor (SLAT). In addition, a negative control treatment was included with birds kept on used litter from day 1 (NEG). Behavior was recorded in weeks 1, 2, 5, and 6. In week 5, treatments affected the behavioral repertoire (p ≤ 0.035). Birds in POS-1 showed more locomoting, preening and activity overall compared to MAT and/or SLAT treatments. Birds in POS-29 showed more drinking, foraging, preening and overall activity than birds in MAT and/or SLAT treatments. In week 6, birds in the POS-1 treatment spent more time foraging compared to birds in all MAT and SLAT treatments (p ≤ 0.030). In addition, birds in the POS-1 treatment spent more time preening than birds in the MAT-1 treatment (p = 0.046). Our results indicate that access to partially slatted flooring and/or disinfectant mats does not benefit broiler chicken welfare in terms of their ability to express highly motivated behaviors. Access to clean, regularly replaced litter is beneficial for broiler chicken welfare in terms of their ability to express their normal behavioral repertoire.

Enrofloxacin Dose Optimization for the Treatment of Colibacillosis in Broiler Chickens Using a Drinking Behaviour Pharmacokinetic Model.

Enrofloxacin is frequently administered via drinking water for the treatment of colibacillosis in broiler chickens. However, the EMA/CVMP has urged to re-evaluate historically approved doses, especially for antimicrobials administered via drinking water. In response, the objectives of this study were two-fold. First, to evaluate the pharmacokinetics (PK) of enrofloxacin following IV, PO and drinking water administration. Second, to predict the efficacy of a range of doses in the drinking water for the treatment of APEC infections. For the first objective, PK parameters were estimated by fitting a one-compartmental model with a zero-order IV infusion and an oral absorption lag function to the simultaneously modelled IV and PO data. After fixing these parameter values, a drinking behaviour pharmacokinetic (DBPK) model was developed for the description and prediction of drinking water PK profiles by adding three model improvements (different diurnal and nocturnal drinking rates, inter-animal variability in water consumption and taking account of dose non-proportionality). The subsequent simulations and probability of target attainment (PTA) analysis predicted that a dose of 12.5 mg/kg/24 h is efficacious in treating colibacillosis with an MIC up to 0.125 µg/mL (ECOFF), whereas the currently registered dose (10 mg/kg/24 h) reaches a PTA of 66% at ECOFF.

Spontaneous Phage Resistance in Avian Pathogenic Escherichia coli.

Avian pathogenic Escherichia coli (APEC) is one of the most important bacterial pathogens affecting poultry worldwide. The emergence of multidrug-resistant pathogens has renewed the interest in the therapeutic use of bacteriophages (phages). However, a major concern for the successful implementation of phage therapy is the emergence of phage-resistant mutants. The understanding of the phage-host interactions, as well as underlying mechanisms of resistance, have shown to be essential for the development of a successful phage therapy. Here, we demonstrate that the strictly lytic Escherichia phage vB_EcoM-P10 rapidly selected for resistance in the APEC ST95 O1 strain AM621. Whole-genome sequence analysis of 109 spontaneous phage-resistant mutant strains revealed 41 mutants with single-nucleotide polymorphisms (SNPs) in their core genome. In 32 of these, a single SNP was detected while two SNPs were identified in a total of nine strains. In total, 34 unique SNPs were detected. In 42 strains, including 18 strains with SNP(s), gene losses spanning 17 different genes were detected. Affected by genetic changes were genes known to be involved in phage resistance (outer membrane protein A, lipopolysaccharide-, O- antigen-, or cell wall-related genes) as well as genes not previously linked to phage resistance, including two hypothetical genes. In several strains, we did not detect any genetic changes. Infecting phages were not able to overcome the phage resistance in host strains. However, interestingly the initial infection was shown to have a great fitness cost for several mutant strains, with up to ∼65% decrease in overall growth. In conclusion, this study provides valuable insights into the phage-host interaction and phage resistance in APEC. Although acquired resistance to phages is frequently observed in pathogenic E. coli, it may be associated with loss of fitness, which could be exploited in phage therapy.

Classification of In Vitro Phage-Host Population Growth Dynamics.

The therapeutic use of bacteriophages (phage therapy) represents a promising alternative to antibiotics to control bacterial pathogens. However, the understanding of the phage-bacterium interactions and population dynamics seems essential for successful phage therapy implementation. Here, we investigated the effect of three factors: phage species (18 lytic E. coli-infecting phages); bacterial strain (10 APEC strains); and multiplicity of infection (MOI) (MOI 10, 1, and 0.1) on the bacterial growth dynamics. All factors had a significant effect, but the phage appeared to be the most important. The results showed seven distinct growth patterns. The first pattern corresponded to the normal bacterial growth pattern in the absence of a phage. The second pattern was complete bacterial killing. The remaining patterns were in-between, characterised by delayed growth and/or variable killing of the bacterial cells. In conclusion, this study demonstrates that the phage-host dynamics is an important factor in the capacity of a phage to eliminate bacteria. The classified patterns show that this is an essential factor to consider when developing a phage therapy. This methodology can be used to rapidly screen for novel phage candidates for phage therapy. Accordingly, the most promising candidates were phages found in Group 2, characterised by growth dynamics with high bacterial killing.

Persecution of Birds of Prey in Flanders: A Retrospective Study 2011-19.

For decades birds of prey have been under the protection of European law, but deliberate or unintentional killing is still a large-scale problem in Europe. In an effort to monitor illegal practices, the Flemish government established several bird of prey hotlines in 2006. Since then, every suspicious death of a bird of prey has been investigated. This retrospective study reviews the necropsy results of every bird of prey submitted for investigation from January 2011 to December 2019, with a focus on illegal practices. In 36.7% (83/226) of all necropsy cases, an illegal cause of death was found, with poisoning being demonstrated in 88% (73/83) of these cases. Cholinesterase inhibitors were the most commonly used toxins, despite being prohibited in Europe. With a prevalence of 82.5% (260/315) of all cases, the Common Buzzard (Buteo buteo) was the species most submitted for necropsy.

Remedying Contact Dermatitis in Broiler Chickens with Novel Flooring Treatments.

Contact dermatitis (footpad dermatitis (FPD), hock burns, and breast dermatitis) is a welfare issue for broiler chickens, causing pain and behavioral restrictions. Once lesions develop, often nothing is done to remedy the issue for the affected flock. Our objective was to evaluate novel flooring treatments at the flock level by providing preventative and remedial treatments against contact dermatitis, plumage soiling, and gait impairment. Broilers (n = 546) were housed in 42 pens, with 13 birds/pen. The flooring treatments (four) included used litter (NEG), new pine shavings replaced regularly (POS), a mat filled with 1% povidone-iodine solution (MAT), and the iodine mat placed on a slatted floor (SLAT). Flooring treatments were provided from day one of age (preventative approach; PREV) or day 29 (remedial approach; REM). Contact dermatitis, soiling, gait, and weight were recorded weekly (seven birds/pen). Results showed a treatment effect for all measures, dependent on bird age. Overall, the POS treatment resulted in the best welfare outcomes (FPD, hock burns, and gait). The worst contact dermatitis was found in the MAT and SLAT groups. NEG birds showed little contact dermatitis, opposite to expectations. Weights were lower for PREV-POS in week seven only. The treatments with povidone-iodine were deemed ineffective against contact dermatitis. Access to clean litter prevented and remedied contact dermatitis, and a comparable approach may be commercially feasible.

Evaluation of Fluoroquinolone Resistance in Clinical Avian Pathogenic Escherichia coli Isolates from Flanders (Belgium).

Fluoroquinolones are frequently used antimicrobials for the treatment of avian pathogenic Escherichia coli (APEC) infections. However, rapid development and selection of resistance to this class of antimicrobial drugs is a significant problem. The aim of this study was to investigate the occurrence and mechanisms of antimicrobial resistance against enrofloxacin (ENRO) in APEC strains in Flanders, Belgium. One hundred and twenty-five APEC strains from broilers with clinical colibacillosis were collected in Flanders from November 2017 to June 2018. The minimum inhibitory concentration (MIC) of all strains and the mutant prevention concentration (MPC) of a sample of sensitive isolates were determined using a commercial gradient strip test and via the agar dilution method, respectively. Non-wild type (NWT) isolates were further characterized using polymerase chain reaction (PCR), gel electrophoresis and gene sequencing. Forty percent of the APEC strains were NWT according to the epidemiological cut-off (ECOFF) measure (MIC > 0.125 µg/mL). With respect to clinical breakpoints, 21% were clinically intermediate (0.5 ≤ MIC ≤ 1 µg/mL) and 10% were clinically resistant (MIC ≥ 2). The MPC values of the tested strains ranged from 0.064 to 1 µg/mL, resulting in MPC/MIC ratios varying from 4 to 32. The majority (92%) of the NWT strains carried one or two mutations in gyrA. Less than a quarter (22%) manifested amino acid substitutions in the topoisomerase IV parC subunit. Only three of the NWT strains carried a mutation in parE. Plasmid mediated quinolone resistance (PMQR) associated genes were detected in 18% of the NWT strains. In contrast to the relatively large number of NWT strains, only a small percentage of APEC isolates was considered clinically resistant. The most common MPC value for sensitive strains was 0.125 µg/mL. Some isolates showed higher values, producing wide mutant selection windows (MSW). Chromosomal mutations in DNA gyrase and topoisomerase IV were confirmed as the main source of decreased antimicrobial fluoroquinolone susceptibility, de-emphasizing the role of PMQR mechanisms.

Killing individual poultry on-farm-a survey among veterinarians and farmers.

To date, information about reasons to select and kill poultry on-farm and which method veterinarians and poultry producers preferably use is scarce. Little is also known about their knowledge of the legislation regarding on-farm killing methods and of methods alternative to the one(s) they use, as well as their perception of those alternatives. In this study, Flemish poultry veterinarians (n = 13), broiler chicken producers (n = 27), and turkey producers (n = 4) were surveyed on killing methods they currently use in practice and alternative methods, on their opinion about what constitutes an appropriate method for on-farm killing of poultry, and on their reasons for killing. All poultry veterinarians and chicken producers who filled out the survey kill poultry by manual cervical dislocation (CD), whereas some turkey farmers also indicated killing by percussive blow to the head (n = 1) or exsanguination (n = 1). Turkey producers seem to be more inclined not to kill animals with injuries or symptoms of disease as compared to veterinarians or chicken producers, such that moribund turkeys are more likely to remain in the flock. Veterinarians considered the following properties of a killing method important: animal friendliness, applicability inside the stable, a high success rate, and time efficiency. Producers ranked the properties similarly, but for them, ease of performance and cost-efficiency were more important than applicability inside the stable. Producers scored those killing properties rather positively for manual as well as mechanical CD. Veterinarians and chicken producers considered the captive bolt method to be easy to perform, to have a high success rate, to be feasible to perform in the stable, and to be animal-friendly. Turkey producers, however, had doubts about the latter 2 properties. Gas, injection, and electrocution were inferior methods to kill poultry according to producers. In conclusion, manual CD is the most common method for killing broiler chickens and turkeys, and knowledge of, and experience with, alternative methods is very limited, both among veterinarians and producers. Informing them about legislation and training for the use of alternative killing techniques are recommended.