Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) are regarded as the most clinically and economically important avian Mycoplasma species, posing significant challenges to the poultry industry worldwide. In this study, MG and MS antibodies were detected by ELISA in 857 unvaccinated Chinese native chickens from 21 breeder flocks on four multi-age farms. The overall seropositive rates were 86.3% for MG and 98.4% for MS. Offspring from an infected breeder flock were reared under different environmental conditions, and serological monitoring was conducted over a 68-week production cycle. The antibody titers and seropositive rates of both mycoplasmas in birds reared in an isolation room were significantly lower than those in birds reared on the farm after maternal antibodies vanished. By adopting strict biosecurity measures, MG and MS infections were effectively controlled in an offspring flock derived from infected breeders, as evidenced by a substantial decrease in seropositive rates. The results suggested that MG and MS infections were prevalent in the breeder flocks of Chinese native chickens. Horizontal rather than vertical infection was the primary cause of high flock infection levels under field conditions. Strict biosecurity measures could be adopted to initially control MG and MS infections in offspring from the breeder flocks with high infection levels.
Escherichia coli is predominantly an intestinal commensal; however, avian pathogenic E. coli (APEC) causes colibacillosis in poultry. The APEC pathotype lacks a clear genetic definition, further complicated by its opportunistic nature. To compare the genomic characteristics of avian pathogenic and commensal E. coli, isolates from diseased and healthy broiler flocks in Sweden were analysed, collected between 2022 and 2024. Clinical isolates (n=202) were collected at necropsy from 40 flocks during colibacillosis outbreaks, and non-clinical isolates (n=109) were obtained from litter using sock sampling in 60 unaffected flocks. Whole-genome sequencing was performed to determine sequence types (STs), serotypes, phylogroups, virulence-associated genes (VAGs) and to identify ColV plasmids. A five-gene APEC marker panel targeting plasmid-associated virulence genes (iutA, hlyF, iss, iroN and ompT) was used to classify isolates as APEC or non-APEC, and high-risk clones were identified according to the APECtyper scheme. Clinical isolates comprised 22 STs and 25 serotypes and were dominated (59%) by the ST23 O78:H4 clone within phylogroup C. Non-clinical isolates were more diverse (44 STs, 67 serotypes), primarily within phylogroups A (48%) and B1 (33%), with no clone predominating. Clinical isolates carried significantly more VAGs (P<0.001). Overall, 97% of clinical isolates were identified as APEC, all of which carried a ColV plasmid. Among non-clinical isolates, 28% were APEC, of which 80% were ColV-positive. However, clinical APEC isolates carried significantly more ColV-associated virulence gene clusters than non-clinical APEC isolates (P<0.001). Only 5% of non-APEC isolates were ColV-positive. High-risk clones were restricted to clinical APEC isolates (63%). These findings indicate that colibacillosis in Swedish broilers was largely driven by a dominant APEC clone during the study period, highlighting the need for coordinated surveillance and targeted control of high-risk clones. The presence of VAG reservoirs among isolates from unaffected flocks, together with the limitations of marker-based APEC typing, supports integrated frameworks combining lineage, VAG profiles and plasmid content for more reliable APEC identification and pathogenicity assessment.
Reproductive activity imposes significant physiological demands on rams. This study evaluated metabolic and hormonal fluctuations in Sarda rams under semi-extensive management conditions, together with flock reproductive outcomes. Fourteen rams were isolated from ewes, subjected to nutritional flushing, and treated with melatonin implants (3 × 18 mg) before joining the flock. From June to December, body condition score (BCS), non-esterified fatty acids (NEFA), urea, triglycerides, cholesterol, testosterone, faecal thyroid hormone metabolites (FTMs), and faecal corticosteroid metabolites (FCMs) were measured every 45 days. Ewes' pregnancy rates (PRs) and conception dates were determined by ultrasound scanning to estimate flock reproductive performance. BCS declined (p < 0.05) from June (3.11 ± 0.06) to November (2.80 ± 0.06). In November, NEFA, cholesterol and FCMs peaked (p < 0.05), whereas triglycerides and urea reached the lowest levels (p < 0.05). FTMs peaked in June and November (p < 0.05). Testosterone concentrations were three-fold higher in June than the rest of the mating season (p < 0.05), while overall PR was stable. Despite metabolic and endocrine changes in rams, overall flock reproductive performance remained stable. The final stage of mating season may represent a strategic period for targeted management strategies to sustain welfare and long-term performance.
Low-pathogenic avian influenza (LPAI) outbreaks in turkey breeder flocks can significantly impair egg production and impact economic viability, particularly in regions densely populated with swine production. In December 2024, after an egg production drop in one barn of an otherwise normal four-barn, 54 wk-of-age turkey breeder flock in southwestern Ontario, Canada, an H1N2 LPAI strain was detected. Following PCR confirmation, a controlled nonfasted molt was initiated across the four barns to mitigate production losses and facilitate a relatively uniform viral clearance. Diagnostic monitoring included serial PCR and ELISA testing during and after molt. Results indicated rapid horizontal transmission during the molt, with all barns seroconverted by 56 wk of age. The flock achieved negative PCR status by week 60, and subsequent testing confirmed clearance of the pathogen. Postmolt production resumed at acceptable levels, suggesting that facilitated molting may serve as a viable management strategy for LPAI outbreaks in high-value breeder operations. This case highlights the potential role of molting as an adjunct to biosecurity and regulatory measures, though controlled studies are needed to further validate efficacy and further consider welfare implications. Reporte de caso- Muda inducida como estrategia de manejo durante un brote de influenza aviar H1N2 de baja patogenicidad en una parvada de pavos reproductores. Los brotes de influenza aviar de baja patogenicidad (LPAI) en parvadas de pavos reproductores pueden comprometer significativamente la producción de huevo y afectar la viabilidad económica, particularmente en regiones con una alta densidad de producción porcina. En diciembre de 2024, tras una caída en la producción de huevo en una de las casetas de una parvada de pavos reproductores de 54 semanas de edad que, por lo demás, se mantenía en condiciones normales y constaba de cuatro naves, se detectó una cepa de influenza aviar de baja patogenicidad H1N2 en el suroeste de Ontario, Canadá. Tras la confirmación mediante PCR, se inició un proceso de muda controlada sin ayuno en las cuatro casetas con el fin de mitigar las pérdidas de producción y facilitar una eliminación viral relativamente uniforme. El monitoreo diagnóstico incluyó pruebas seriadas de PCR y ELISA tanto durante como después del proceso de muda. Los resultados indicaron una rápida transmisión horizontal durante la muda, observándose seroconversión en todas las casetas para la semana 56 de edad. La parvada alcanzó un estado negativo en las pruebas de PCR para la semana 60, y los análisis posteriores confirmaron la eliminación del patógeno. La producción posterior a la muda se reanudó a niveles aceptables, lo que sugiere que la muda inducida podría constituir una estrategia de manejo viable para los brotes de LPAI en explotaciones de reproductores de alto valor. Este caso pone de relieve el papel potencial de la muda como medida complementaria a las prácticas de bioseguridad y a las normativas sanitarias, si bien se requieren estudios controlados para validar con mayor rigor su eficacia y evaluar más a fondo sus implicaciones en el bienestar animal.
We show that even weak nonreciprocal alignment leads to large-scale structure formation in flocking mixtures. By combining numerical simulations of a binary Vicsek model and the analysis of coarse-grained continuum equations, we demonstrate that nonreciprocity destabilizes the ordered phase formed by mutually aligning or antialigning species in a large part of the phase diagram. For aligning populations, this instability results in one species condensing in a single band that travels within a homogeneous liquid of the other species. When interactions are antialigning, both species self-assemble into polar clusters with large-scale chaotic dynamics. In both cases, the emergence of structures is accompanied by the demixing of the two species, despite the absence of repulsive interactions. Our theoretical analysis allows us to elucidate the origin of the instability, and show that it is generic to nonreciprocal flocks.
The poultry sector of Pakistan plays a significant role in food security, yet faces various challenges including infectious agents. Chicken Anemia Virus (CAV) and Escherichia coli (E. coli) are major pathogens due to their immunosuppressive and opportunistic nature, respectively. Since co-infections can increase disease severity and financial losses in poultry production, the aim of this study was to identify and genetically characterize CAV and E. coli from co-infections in commercial poultry in Lahore, Punjab, Pakistan. A total of 40 samples were collected; bone marrow samples for CAV and liver and spleen tissues for E. coli detection. DNA was extracted using an automated extractor. Polymerase chain reaction targeted VP1 gene of CAV and uspA gene of E. coli. Culture and biochemical tests were also used to identify E. coli isolates prior to PCR. Amplicons were sequenced and analyzed phylogenetically. Descriptive statistics indicated an overall 15% (6/40) co-infection of CAV and E. coli. Co-infections were more frequent in commercial layer flocks compared to broilers and in < 24 days-old chickens compared to > 24 days-old. More co-infections were observed in the Spring than in Winter and Summer, however, no statistically significant association was found. Phylogenetic analysis of VP1 gene of CAV from co-infections showed genetic similarity with strains from Europe, Asia, and South America, while the uspA gene of E. coli showed genetic similarity with isolates from South Asian countries. This study highlights the occurrence of co-infection in commercial poultry flocks in Lahore, with a higher frequency in young layers during the Spring season.
In the present study, we report the detection of a novel infectious bronchitis virus lineage within genotypes GVII (GVII-2) in commercial flocks in China since 2008. Virus strains within this lineage have been isolated from different geographic regions in China. S1 genes of these viruses have an intralineage divergence of 0.2%-4.4% nucleotides and 0.1%-7.5% amino acids. The pairwise distances of nucleotide and amino acid sequences based on the S1 subunit between GVII-2 and the closest GVII-1 were 28.3% -28.8% and 28.1%-28.9%, respectively. Complete genomic sequence analysis of the first detected strain, ck/CH/LAH/08I (LAH/08I), suggested that it is derived from recombination events with a genomic backbone of the GI-19 ck/CH/LGS/08I-like strain and distinct S, 3a, and 5a genes. The GVII-2 strain represents a unique serotype that differs from the GVII-1 I0636/16 strain in the same genotype and its deduced parental virus GI-19 I0305/19. Strain LAH/08I not only showed strong tissue tropism in the kidneys of SPF chickens but also exhibited high replication capacities in the trachea, kidney, digestive tract, and immune system of infected chickens, attributed to its pathogenicity in SPF chickens. Strain LAH/08I also showed tropism in the oviducts and the ability to induce cystic oviduct formation in adult chickens after infection in baby chicks. Un nuevo linaje del virus de la bronquitis infecciosa dentro del genotipo GVII (GVII-2) representa un serotipo único que circula en parvadas avícolas de China. En el presente estudio, informamos de la detección de un nuevo linaje del virus de la bronquitis infecciosa dentro de los genotipos GVII (GVII-2) en parvadas comerciales en China desde 2008. Se han aislado cepas virales de este linaje en diferentes regiones geográficas de China. Los genes S1 de estos virus presentan una divergencia dentro del linaje de entre el 0.2 % y el 4.4 % de nucleótidos y el 0.1 % y el 7.5 % de aminoácidos. Las distancias pareadas de las secuencias de nucleótidos y aminoácidos, basadas en la subunidad S1, entre GVII-2 y el genotipo GVII-1 más cercano fueron del 28.3 % al 28.8 % y del 28.1 % al 28.9 %, respectivamente. El análisis completo de la secuencia genómica de la primera cepa detectada, ck/CH/LAH/08I (LAH/08I), sugirió que se deriva de eventos de recombinación con una estructura genómica de la cepa GI-19 similar al virus ck/CH/LGS/08I y genes S, 3a y 5a distintivos. La cepa GVII-2 representa un serotipo único que difiere de la cepa GVII-1 I0636/16 en el mismo genotipo y del virus parental deducido, cepa GI-19 I0305/19. La cepa LAH/08I no solo mostró un fuerte tropismo tisular en los riñones de pollos libres de patógenos específicos, sino que también exhibió una alta capacidad de replicación en la tráquea, el riñón, el tracto digestivo y el sistema inmune de los pollos infectados, lo que se atribuye a su patogenicidad en pollos libres de patógenos específicos. La cepa LAH/08I también mostró tropismo en los oviductos y la capacidad de inducir la formación de oviductos quísticos en pollos adultos después de la infección en pollitos.
Modelling small bird flights is challenging, as small birds (<20 g) rarely engage in steady-state flights assumed by traditional flight models. Additionally, their flights are difficult to measure in the field owing to the mass of high-resolution GPS loggers and the low resolution in lightweight geolocators. This study aimed to measure and model spontaneous, non-steady-state take-off flights of wild tit species that forage in mixed flocks during winter, despite differences in body sizes and ecological niches. We recorded 1434 spontaneous flights from 49 individuals of great tits (Parus major), blue tits (Cyanistes caeruleus) and marsh tits (Poecile palustris) in the Paridae family using two automated radio frequency identification infrared tunnels. We developed a power margin model to predict in-flight acceleration based on initial velocity, scaled by species-specific wing loading. Lastly, we tested the repeatability of flight metrics to assess whether flight may be interpreted as an individual behavioural trait. We found significant differences in initial velocity and in-flight acceleration between species. The observed difference in the in-flight acceleration aligned with the power margin model prediction. Finally, we found significant individual repeatability in both initial velocity and in-flight acceleration. Our findings suggest that the flight performance of small birds can be consistently measured in the field, modelled beyond steady-state assumptions and interpreted as an individual behavioural trait.
The present study evaluated the effect of intermittent folic acid supplementation administered via drinking water on the productive and reproductive performance of Ross 308 breeder flocks. The experiment was conducted in two houses (A and B). Birds from house A received folic acid supplementation (10 mg/L for 5 consecutive days at selected ages: 27, 31, 35, 39, 43, 47, 51, and 55 weeks), while the birds from control group (house B) received no supplementation. Egg production, body weight of hens and roosters, egg weight, fertility, hatchability, egg quality traits, and early embryonic mortality were analyzed during the laying period (24-56 weeks of age). The results showed a typical breeder pattern of decreasing egg production and hatchability with advancing age, accompanied by an increase in body weight of birds and egg weight in both groups. Folic acid supplementation resulted in variable and inconsistent effects depending on bird age and the analyzed trait. At specific production weeks, improvements in fertility, hatchability, and early embryonic survival were observed in the supplemented group; however, these effects were not consistently maintained throughout the entire experimental period. Moreover, some egg quality traits, including cracked and deformed eggs, showed an unfavorable or variable response to supplementation in certain weeks. Overall, no uniform effect of intermittent folic acid supplementation was observed across all reproductive and production parameters. While some beneficial effects on selected early embryonic development traits were identified, these responses were age-dependent and inconsistent. However, these effects are age-dependent and not consistently expressed throughout the laying period, indicating the need for further research to determine the optimal dose and supplementation scheme under commercial production conditions.
In July 2021, the School of Veterinary Medicine at Amol University of Special Modern Technologies was informed of high mortality within a sheep flock. Out of 200 animals, 24 sheep died within a few days. Due to the rapid deaths, poisoning was initially suspected but ruled out after clinical observation, sampling, and necropsy. A full herd assessment was performed, and blood and fecal samples were collected from lambs and adults for laboratory analysis. Blood samples were drawn via jugular venipuncture; fecal samples were examined using the Modified McMaster technique to detect helminth eggs or protozoan oocysts. For hematological and biochemical evaluation, blood was divided into EDTA and plain tubes. Serum analysis revealed a significant elevation in AST levels, indicating hepatic tissue damage associated with the parenchymal migration of juvenile Fasciola hepatica during acute fascioliasis. Infected sheep showed a marked reduction in serum SOD activity (P<0.001) and a significant increase in MDA levels (P<0.001) compared with non-infected animals, reflecting oxidative stress. These findings suggested that environmental and climatic conditions at the time favored the spread of fascioliasis. Considering the zoonotic potential and widespread occurrence of F. hepatica, effective control and preventive strategies are essential. Recommended measures include wetland drainage, strategic deworming, and controlling snail and slug populations to limit transmission.
Marek's disease (MD) remains a severe economic concern in poultry industry globally despite decades of vaccination strategies. Particularly challenging are viral infections due to Marek's disease virus (MDV) (Gallid alphaherpesvirus 2, GaHV-2) strains that can escape immune defenses in areas that do not have access to molecular surveillance data. This study performed molecular epidemiology of MDV in Iraqi commercial poultry based on extensive characterization of circulating strains, quantification of subclinical infection in vaccinated flocks, and phylogenetic sequencing to determine evolutionary relationships with local isolates. A cross-sectional surveillance on five commercial layer pullet flocks given the CVI988 vaccine took place from March to June 2024. A combined sample of 250 birds (50 birds per flock) was collected from Alrashdia in Baghdad Province. In this study, estimates were made for samples based on 5% expected prevalence, 95% confidence level, and 3% precision. Pulpy feather follicles and tissues were isolated for molecular detection of MDV meq oncogene by PCR amplification with known primers. Sanger sequencing was performed later and phylogenetic reconstruction carried out using the maximum likelihood technique. Prevalence of subclinical MDV was 3.2% (8/250) in surveyed flocks, with significant operational heterogeneity (0%-6%). One flock had an acute clinical outbreak, and 86.7% of birds afflicted during the surveillance period showed paralysis. Molecular analysis revealed genetically homogeneous strain (Iraq/Baghdad/2024) with 99.8% nucleotide identity to Iranian very virulent isolates, with clustering in the very virulent pathotype clade and high bootstrap support (98%). This research describes the circulation of a very virulent, genetically uniform GaHV-2 strain capable of inducing vaccine breakthrough in Iraqi commercial poultry. The phylogenetic proximity to regional isolates suggests transboundary virus movement as a possible route of attack and highlights a gap in the level of molecular surveillance and optimization of Middle Eastern poultry production systems in immunization programs.
Cellulitis in commercially reared broiler chickens is a common cause of condemnation at slaughter. In this retrospective observational study, we aimed to identify parameters in the broiler production chain that could be associated with the condemnation percentage due to dermatitis/cellulitis at meat inspection. Production data were acquired from an industry production database and involved 90 farms and 4697 broiler chicken flocks placed from May 2021 to November 2022. Data were analysed using mixed effect modelling with broiler compartment nested in farm as the random effect. The analyses showed that higher mean age of parent flocks and higher stocking density at placement in combination with age of chicken flocks at slaughter were associated with higher condemnation due to dermatitis/cellulitis. Higher footpad score was associated with lower condemnation due to dermatitis/cellulitis, even at the slaughterhouse which had a higher dermatitis/cellulitis condemnation percentage. In flocks where thinning was practiced, defined as by more than four days between slaughter occasions, there was lower condemnation due to dermatitis/cellulitis. In addition, small broiler compartments, season, feed mills and feed company were associated with the outcome. There was a risk of information bias as multiple stakeholders contributed data. As several parameters were associated with condemnation due to dermatitis/cellulitis the results suggest a multi-factorial preventive approach. Further, the study emphasizes the need for further research to understand how these parameters affect the condemnation due to dermatitis/cellulitis.
Both fear and exploration have been shown to have relationships with animal welfare and animal production. As such, there is an ongoing need to identify the joint effects, including interactions, of current and developing management practices and production systems on fear and exploration in laying hens. This study aimed to investigate relationships between laying hen responses to novelty and humans, and both management and environmental factors in commercial Australian free-range egg farms. This study assessed 64 flocks of laying hens across 3 commercial organisations in Australia. For each flock, behavioural responses towards both a novel object and an unfamiliar human were assessed when the hens were between 30 and 46 weeks of age. Management and environmental data were collected through farm records, interviews with farm managers and weather stations. Data were analysed using generalised linear mixed models. Several key relationships were identified. Despite the breeds being promoted as similar in physical appearance, behavioural characteristics and production values, Hyline brown flocks showed less fear of humans in both the 'shed and 'range' areas and less fear of the novel object in the range compared to the flocks of ISA brown. Hens housed in aviary systems were less fearful of humans based on less avoidance of an unfamiliar human compared to hens housed in flat deck systems. Decreased feeder space per hen was strongly associated with increased fear of the novel object. Random site effects for the hen responses to humans, and random shed effects for the hen response to a novel object when outside, were also detected, highlighting the importance of stockperson attitudes and behaviour which may be influenced by differences in work culture at different sites. Awareness of these relationships could lead to adaptive changes in management practices which result in better outcomes both in terms of hen welfare and productivity.
In most sheep production systems, the ideal scenario is for every ewe to lamb and successfully raise twins. However, selection for increased number of lambs born (NLB) is often accompanied by a higher incidence of triplet and higher-order births, which increases management challenges and producer reluctance to intensify selection for this trait. Therefore, there is a need to identify animals who not only exhibit a high twinning rate, but also canalized reproductive performance, characterized by consistent expression of twin births and reduced variability toward extreme litter sizes. In this context, the double hierarchical generalized linear model (DHGLM) provides a mechanism to evaluate both the mean and the dispersion components of a trait, enabling the evaluation of the heteroskedastic residual variance for each animal, and thereby select animals with lower residual variances. Therefore, the main objectives of this study were to estimate (co)variance components and genetic parameters for the mean and dispersion traits related to number of lambs born and twinning rate and to develop a strategy to identify rams whose daughters consistently produce twins. Data from the US Sheep Experiment Station (USSES; Dubois, ID, USA) Polypay flock recorded from 1999 to 2025 included 8061 litters (3115 dams; 293 sires) and the Rambouillet flock included 5948 litters (2333 dams; 228 sires) recorded from 2005 to 2025. The proportion of twin litters have significantly decreased in the Polypay flock while remaining unchanged (p = 0.13) in the Rambouillet flock. For both breeds, the proportion of single lamb litters have decreased while triplets have increased. For sires with a minimum of 15 daughter litters, the average litter size was 1.53 ± 0.55 for 1-year-old ewes and 2.29 ± 0.75 for mature ewes for the Polypay and 1.24 ± 0.43 for 1-year-old ewes and 1.93 ± 0.64 for mature ewes for the Rambouillet. A DHGLM was used to estimate both the mean and dispersion of the NLB3 considering 3 classes (1, 2 or 3+) and NLB for all classes (1 to 5 for Polypay and 1 to 4 for Rambouillet) traits using the DHGLMF90 package. A bivariate animal model was fitted each for NLB3 and NLB, and their associated dispersions (vNLB3 and vNLB) with contemporary group as a concatenation of ewe age category and birth year fitted as a categorical fixed effect and animal (ewe), permanent environment, and the residual as random effects for a model including data from all ewes (ALL) and excluding phenotypic records from 1-year-old ewes (MATURE). The same mean traits and twinning (TWIN; 1 for non-twins and 2 for twins) were evaluated using a threshold model with the THRGIBBSF90 package. Heritability estimates ranged from 0.024 ± 0.012 for vNLB3 analysed using the DHGLM model to 0.110 ± 0.020 for NLB3 analysed using the threshold model for the ALL Polypay dataset and from 0.016 ± 0.014 for vNLB3 analysed using the DHGLM model to 0.094 ± 0.022 for NLB3 analysed using the threshold model for the MATURE Polypay dataset. For the Rambouillet, heritability estimates ranged from 0.020 ± 0.013 for TWIN analysed using the threshold model to 0.150 ± 0.022 for NLB analysed using the threshold model for the ALL dataset and from 0.021 ± 0.012 for vNLB3 analysed using the DHGLM model to 0.151 ± 0.023 for NLB analysed using the threshold model for the MATURE dataset. The estimated breeding values (EBV) were filtered if lower than the square root of heritability, or the equivalent of a single phenotypic record and correlations of EBV among animals were compared. Correlations among all NLB approaches were high (0.80 to 1.00) for both breeds, indicating high agreement between NLB considering differing numbers of classes and also for different models (DHGLM and threshold). Theoretical accuracies were evaluated for all animals and sires with more than 15 daughter litters. The TWIN trait analysed using a threshold model and the vNLB trait analysed using the DHGLM model were selected to represent twinning rate using the MATURE dataset for both breeds. Of the sires, 9.9% of Polypay and 32.1% of Rambouillet had both positive TWIN EBV and negative vNLB EBV, suggesting that progress can be achieved for both increased twins and canalization of number of lambs born. Extension of twinning rate to national genetic evaluation is warranted to meet the needs of US sheep producers.
Between 2017 and 2019, 10 broiler flocks, with birds exhibiting neck paralysis, nervous tics, and torticollis, were submitted for necropsy and additional tests. These neurologic signs were mostly observed in certified, nonvaccinated broilers (8 of 10), ranging between 45 and 56 days of age. No specific lesions were described at macroscopic examination. Histopathology revealed moderate to severe lymphocytic infiltration of the central nervous system (CNS). In addition, peripheral nerves and visceral organs were commonly affected, although less severely. Immunohistochemistry identified the infiltrating lymphocytes as CD3+ T cells, and Marek's disease (MD) virus was detected by real-time PCR in brain formalin-fixed and paraffin-embedded samples in all flocks. In conclusion, MD is still a concern in France. The occurrence of MD CNS syndromes should be considered in commercial broilers starting from 6 wk of age because these conditions could compromise the health and welfare of affected birds. Poultry veterinarians should be aware of this atypical form of MD to ensure proper diagnosis and assess the impact of the disease, especially in nonvaccinated chicken flocks. Reporte de caso- Enfermedad de Marek en Francia: Diez casos de síndromes del sistema nervioso central. Entre 2017 y 2019, se sometieron a necropsia y pruebas adicionales 10 parvadas de pollos de engorde, con aves que presentaban parálisis de cuello, tics nerviosos y tortícolis. Estos signos neurológicos se observaron principalmente en pollos de engorde certificados y no vacunados (8 de 10), de entre 45 y 56 días de edad. No se describieron lesiones específicas en el examen macroscópico. La histopatología reveló una infiltración linfocítica de moderada a grave del sistema nervioso central (SNC). Además, los nervios periféricos y las vísceras se vieron afectados con frecuencia, aunque de forma menos grave. La inmunohistoquímica identificó los linfocitos infiltrados como células T CD3+, y el virus de la enfermedad de Marek se detectó mediante PCR en tiempo real en muestras de cerebro fijadas en formalina e incluidas en parafina en todas las parvadas. En conclusión, la enfermedad de Marek sigue siendo una preocupación en Francia. Se debe considerar la aparición de síndromes en el sistema nervioso central relacionados con la enfermedad de Marek en pollos de engorde comerciales a partir de las seis semanas de edad, ya que estas afecciones podrían comprometer la salud y el bienestar de las aves afectadas. Los veterinarios avícolas deben conocer esta forma atípica de la enfermedad de Marek para garantizar un diagnóstico adecuado y evaluar el impacto de la enfermedad, especialmente en aves no vacunadas.
Alternative poultry production systems are increasing due to consumer concerns regarding conventional farming practices and the growing demand for more sustainable systems that promote animal welfare. In this context, backyard poultry keeping for hobby or self-consumption purposes has become increasingly common in both rural and urban areas. However, unlike commercial poultry production, these flocks are often managed with limited biosecurity and sanitary measures, and their role in the maintenance and dissemination of antimicrobial-resistant bacteria remains poorly understood. Therefore, this study aimed to characterize the epidemiological situation of antimicrobial resistance (AMR) in backyard poultry farms in eastern Spain using Escherichia coli as an environmental sentinel bacterium. Owners of backyard poultry across eastern Spain were invited to voluntary take. Epidemiological data on flock management and biosecurity practices were collected to evaluate farm biosecurity levels. For E. coli isolation, cloacal swabs were obtained from up to six hens per farm, and two environmental surface wipes were collected from each facility. In total, 33 backyard poultry farms from 24 localities were randomly sampled. The survey revealed a wide range of biosecurity levels, with low (36.4%) and moderate (57.6%) biosecurity levels being the most common. Overall, 246 samples were collected, yielding 216 E. coli isolates, including 168 from animal samples and 48 from environmental samples. Among animal isolates, 95.8% showed resistance to at least one antimicrobial and 73.8% exhibited a multidrug-resistant (MDR) phenotype. Similarly, 97.9% of environmental isolates were resistant and 75% were MDR. The highest resistance rates in animal and environmental isolates were observed for tetracycline (86.9% and 91.7%, respectively) and ampicillin (82.7% and 85.4%, respectively). These findings reveal a high burden of AMR in backyard poultry environments. The limited implementation of biosecurity measures and frequent contact with wildlife and other animals may contribute to this situation. These results emphasize the importance of including backyard poultry systems in AMR surveillance and control programs under a One Health approach.
Phasianus chaphamaparvovirus 1 is a newly recognized pathogen associated with high mortality in young pheasant chicks with significant losses for pheasant breeders. Here we present an outbreak of necrotizing hepatitis with high mortality in a flock of young pheasant chicks in Bosnia and Herzegovina associated with Phasianus chaphamaparvovirus 1 and coccidiosis coinfection. Severe necrotizing hepatitis with characteristic intranuclear inclusion bodies in affected hepatocytes was observed on microscopic examination. In addition, multifocal areas of intestinal mucosal necrosis with numerous developing stages (meronts) of coccidia were present. Phasianus chaphamaparvovirus 1 was detected with qPCR from the livers of diseased birds. Our report represents the first data on the presence of this new virus in pheasant flocks in the Balkan region and suggests that the virus is widespread across Europe. It further supports the inclusion of Chaphamaparvovirus as a differential diagnosis of pheasant mortality outbreaks both in breeding facilities and in the wild. Reporte de caso- Hepatitis necrótica asociada a la coinfección por Phasianus chaphamaparvovirus 1 y coccidiosis en faisanes jóvenes (Phasianus colchicus) en Bosnia y Herzegovina. Phasianus chaphamaparvovirus 1 es un patógeno de reciente reconocimiento asociado a una elevada mortalidad en faisanes jóvenes, lo que conlleva pérdidas significativas para los criadores de esta especie. En el presente trabajo, se describe un brote de hepatitis necrotizante con alta mortalidad en una parvada de faisanes jóvenes en Bosnia y Herzegovina, asociado a una coinfección por Phasianus chaphamaparvovirus 1 y coccidiosis. El examen microscópico reveló una hepatitis necrotizante grave, caracterizada por la presencia de cuerpos de inclusión intranucleares en los hepatocitos afectados. Asimismo, se observaron áreas multifocales de necrosis en la mucosa intestinal, con presencia de numerosos estadios de desarrollo (merontes) de coccidios. La detección de Phasianus chaphamaparvovirus 1 se realizó mediante qPCR a partir de muestras hepáticas de las aves enfermas. Este informe constituye el primer reporte sobre la presencia de este nuevo virus en parvadas de faisanes en la región de los Balcanes, sugiriendo que dicho virus se encuentra ampliamente distribuido por toda Europa. Además, respalda la inclusión de Chaphamaparvovirus como diagnóstico diferencial ante brotes de mortalidad en faisanes, tanto en instalaciones de cría como en poblaciones silvestres.
Outbreaks of avian infectious bronchitis virus (IBV) often occur in vaccinated flocks. The antibody-dependent enhancement (ADE) has been proposed as a potential mechanism underlying coronavirus vaccine failure. However, this hypothesis has yet to be substantiated in flocks. This study demonstrates ADE occurrence in IBV (gamacoronavirus) in vitro and in vivo. Using the SPF chicken host model, primary infection with an O-glycosylation-modified attenuated strain enhanced pathogenesis upon secondary homologous/heterologous virulent challenge, increasing morbidity/mortality (≥30%), pathological lesions, and viral loads. Notably, sequentially attenuated infections also induced ADE, suggesting live attenuated vaccine risks. The immune serum raised against the O-glycosylation-modified attenuated strain was also pre-mixed with the challenge strain, and the mixtures were then inoculated into target cells, non-susceptible macrophage cells, or a co-culture of both cell types. The serum-virus complexes replicated poorly in macrophages, yet immune cells amplified the expression of inflammatory factors and ADE-mediated viral replication in target cells, indicating a significant promoting role of immune cells in this process. The concentrations of complement component C3 and neutralizing antibodies in the immune serum were also measured, and results showed that the induction of this ADE is associated with high complement component C3 and low neutralizing antibody titers. These findings highlight risks for vaccines and antibody-based therapeutic strategies of coronavirus infection.
Methicillin-resistant Staphylococcus aureus (MRSA) is a serious zoonotic pathogen that poses significant threats to both public health and the poultry industry due to its multidrug resistance and virulence. In broiler chickens, MRSA infections are commonly associated with arthritis, resulting in impaired mobility, reduced productivity, and economic losses. This study aimed to investigate the epidemiology, antimicrobial resistance profiles, and genetic determinants of MRSA in broiler chickens presenting with clinical arthritis in the Kafr El-Sheikh Governorate, northern Egypt. In this study, 100 broiler farms were randomly selected from a list provided by the local veterinary authority in Kafr El-Sheikh Governorate. Of these, 20 medium-sized farms (5000-10,000 birds per cycle) had clinically arthritic chickens. A total of 140 synovial fluid samples (six to eight chickens per farm) were aseptically collected from affected birds. The affected farms represented approximately 4.8% of the total broiler farms in the governorate and were distributed across different districts, indicating that MRSA-associated arthritis was not confined to a single locality. Bacterial isolation was performed using selective culture media and confirmed via biochemical tests and PCR targeting the nuc gene. Antimicrobial susceptibility testing was conducted using the Kirby Bauer disk diffusion method against 16 antibiotics following CLSI 2020 guidelines. Molecular screening for resistance and virulence genes (mecA, vanA, hig) was performed by uniplex PCR. Phylogenetic analysis of 16S rRNA sequences was carried out using the Maximum Likelihood method. Clinical signs included joint swelling, deformity, and impaired locomotion. Epidemiological analysis revealed that MRSA-associated arthritis was detected in (3/20) 15% of infected farms, with 7.67 ± 1.53% of birds affected within infected flocks. Staphylococcus aureus was isolated from 60% of footpad abscesses and 65% of hock joint swellings. All isolates were resistant to multiple β-lactam antibiotics, including oxacillin, cefoxitin, penicillin G, and piperacillin. High resistance was also observed to clindamycin, cephradine, and cephalexin. The most effective agents were ampicillin-sulbactam and vancomycin. The mecA and nuc genes were detected in all isolates, and vanA and hig genes were detected in 5% and 25% of isolates, respectively. Phylogenetic analysis confirmed the close genetic relatedness of the local isolate (PQ879639.1) to global S. aureus strains. MRSA is an emerging pathogen in broiler flocks with a marked capacity for antimicrobial resistance and zoonotic transmission. The detection of multidrug-resistant strains carrying key resistance genes highlights the urgent need for enhanced biosecurity, prudent antimicrobial use, and routine monitoring programs to mitigate its impact on poultry and public health. Epidemiología, resistencia antimicrobiana y determinantes genéticos de Staphylococcus aureus resistente a la meticilina (MRSA) en pollos de engorde con artritis. El Staphylococcus aureus resistente a la meticilina (SARM) es un patógeno zoonótico importante que representa una amenaza significativa tanto para la salud pública como para la industria avícola, debido a su multirresistencia a los fármacos y a su virulencia. En los pollos de engorde, las infecciones por el Staphylococcus aureus resistente a la meticilina se asocian comúnmente con artritis, lo que resulta en una movilidad reducida, una menor productividad y pérdidas económicas. El objetivo de este estudio fue investigar la epidemiología, los perfiles de resistencia antimicrobiana y los determinantes genéticos del Staphylococcus aureus resistente a la meticilina en pollos de engorde que presentaban artritis clínica en la Gobernación de Kafr El-Sheikh, en el norte de Egipto. En este estudio, se seleccionaron aleatoriamente 100 granjas de pollos de engorde a partir de una lista proporcionada por la autoridad veterinaria local de la Gobernación de Kafr El-Sheikh. De estas, 20 granjas de tamaño mediano (5,000-10,000 aves por ciclo) albergaban pollos con artritis clínica. Se recolectó asépticamente un total de 140 muestras de líquido sinovial (de seis a ocho pollos por granja) de las aves afectadas. Las granjas afectadas representaron aproximadamente el 4.8 % del total de granjas de pollos de engorde de la gobernación y se distribuían en diferentes distritos, lo que indica que la artritis asociada al Staphylococcus aureus resistente a la meticilina no se limitaba a una sola localidad. El aislamiento bacteriano se realizó utilizando medios de cultivo selectivos y se confirmó mediante pruebas bioquímicas y por PCR dirigida al gene nuc. Las pruebas de susceptibilidad antimicrobiana se llevaron a cabo mediante el método de difusión en disco de Kirby-Bauer frente a 16 antibióticos, siguiendo las directrices del Instituto de Estándares de Laboratorios Clínicos (CLSI) de 2020. La detección molecular de genes de resistencia y virulencia (mecA, vanA, hig) se realizó mediante PCR uniplex. El análisis filogenético de las secuencias de ARNr 16S se efectuó utilizando el método de máxima verosimilitud. Los signos clínicos observados incluyeron inflamación articular, deformidad y dificultad en la locomoción. El análisis epidemiológico reveló que la artritis asociada al Staphylococcus aureus resistente a la meticilina se detectó en el 15% (3/20) de las granjas infectadas, con un 7.67 ± 1.53 % de aves afectadas dentro de los lotes infectados. Se aisló Staphylococcus aureus del 60% de los abscesos en los cojinetes plantares y del 65% de las inflamaciones en las articulaciones del corvejón. Todos los aislados mostraron resistencia a múltiples antibióticos β-lactámicos, incluyendo oxacilina, cefoxitina, penicilina G y piperacilina. También se observó una elevada resistencia a la clindamicina, la cefradina y la cefalexina. Los agentes más eficaces fueron la ampicilina-sulbactam y la vancomicina. Los genes mecA y nuc se detectaron en todos los aislados, mientras que los genes vanA y hig se detectaron en el 5% y el 25% de los aislados, respectivamente. El análisis filogenético confirmó la estrecha relación genética del aislado local (PQ879639.1) con cepas globales de S. aureus. El Staphylococcus aureus resistente a la meticilina es un patógeno emergente en las parvadas de pollos de engorde, con una marcada capacidad de resistencia antimicrobiana y transmisión zoonótica. La detección de cepas multirresistentes portadoras de genes de resistencia clave subraya la urgente necesidad de reforzar la bioseguridad, promover un uso prudente de los antimicrobianos e implementar programas de vigilancia rutinaria para mitigar su impacto en la salud avícola y pública.
The livestock industry faces growing constraints due to antimicrobial resistance, particularly in poultry systems that have historically relied on antibiotic use. These challenges are exacerbated in free-range production, where restrictions on antimicrobial interventions coincide with heightened exposure to infectious diseases, leading to increased mortality and reduced productivity. On-farm disease outbreaks cannot be reproduced in high ethics standards approved animal houses, where they can be modeled to recognize some patterns of pathogen dynamics. While laboratory settings enable rigorous control and monitoring, they lack the environmental, management, production, pathogen pressures and complexity found on industrial farms and therefore cannot realistically recreate disease progression. Here, we present a field study in a layer flock that experienced three disease outbreaks of spotty liver disease (SLD) and fowl cholera (FC). The treatment group was supplemented with a precision biotic, a synthetic glycan product, while weekly performance measures and responses of microbial populations across major gut sections were observed. The precision biotic supplemented birds showed higher cumulative mortality but also higher egg output. However, as this was an unreplicated field study, these differences should be interpreted as descriptive associations. The intestinal microbial community responded differently to supplementation under concurrent environmental and disease pressures. This study provides large-scale field observations during concurrent outbreaks of SLD and FC, offering real-world insights that may inform future controlled studies of disease dynamics and performance management. KEY POINTS: • Free-range systems increase disease risk, reducing health and productivity in layer flocks. • Precision biotics were associated with higher egg output and higher cumulative mortality in hens. • Gut microbiota and liver congestion differed between precision biotic supplemented and control groups.