Search Results (463)

Flapping-wing drones (FWDs), owing to their compact size and operation in cluttered and unsteady airflow environments, encounter significant aerodynamic and stability challenges. Studies of avian flight reveal that falcons and other raptors actively deflect their covert feathers to mitigate gusts and maintain stable flight. Drawing inspiration from this mechanism, this study presents a peregrine falcon-inspired Active Flow Control Unit (AFCU) integrated with a Deep Deterministic Policy Gradient (DDPG)-based deep reinforcement learning (DRL) controller for real-time disturbance attenuation. The AFCU employs mechanical covert feathers (MCFs) that actuate to dissipate gust loads during high wind conditions. A reduced-order bond graph model that encapsulates the nonlinear interaction between the primary wing and the feather-based active flow control surfaces is created which is used as a dynamic training environment for the DDPG agent. Utilizing closed-loop interactions, the successfully obtained learned policy produces optimal actuator forces to reduce feather-displacement error and aerodynamic load variations. The designed controller stabilizes the internally unstable open-loop AFCU, attaining near-zero steady-state error and settling times under 1.6 s for gust magnitudes ranging from 12.5 to 20 m/s. Simulations further illustrate a reduction of up to 50% in gust-induced loads compared to traditional approaches. This integration of bio-inspired design with learning-based active flow control offers a viable avenue for the development of highly adaptive and gust-resilient flapping-wing aerial systems. Full article

Salmonella Enteritidis (SE) infections in poultry threaten animal health and food safety. Antibiotic resistance makes alternative treatments necessary. Bamboo polyphenols (BP), recovered from bamboo vinegar—a byproduct of bamboo carbonization—represent a sustainable and eco-friendly candidate for combating avian salmonellosis. We tested BP against SE using laboratory tests and a chick model. BP showed a minimum inhibitory concentration of 1:256 against SE. We infected chicks with 1.8 × 10⁸ CFU per bird. The results indicated that adding 0.2% (v/v) BP to drinking water demonstrated optimal efficacy for prevention. Adding 0.4% (v/v) BP demonstrated optimal efficacy for treatment. Prophylactic BP administration effectively prevented SE-induced mortality and tissue damage. As a therapeutic agent, BP performed comparably to berberine. BP lowered the bacterial load in organs and increased chick survival to 96%. At the transcriptional level, BP administration downregulated the TLR4/MyD88/NF-κB pathway. It also improved antioxidant levels, strengthened the intestinal barrier, and restored healthy gut bacteria. These results indicate that BP could serve as a potential and sustainable feed additive to reduce SE infection in poultry. Full article

Solitary living is an evolutionarily widespread yet comparatively under-theorized social system, despite its occurrence across diverse animal taxa. Shrikes (family Laniidae) are small predatory passerines that combine raptorial behavior, strong territoriality, and predominantly solitary space use, making them a powerful model for examining the ecology and evolution of solitary living. Here, I synthesize published work on shrike behavioral ecology and explicitly link these traits to the costs and benefits of a solitary lifestyle. I argue that shrikes exemplify how solitary species can offset the absence of social buffering through cognitive innovation, finetuned habitat selection, and flexible yet tightly bounded sociality. I then compare shrike ecology to solitary mammals and reptiles, highlighting convergent patterns in resource dispersion, spatial memory, risk management, and juvenile dispersal. I further examine how anthropogenic pressures, such as habitat fragmentation, climatic instability, and urbanization, interact with solitary life histories and review evidence from management interventions in both European farmland and North American systems that demographic recovery is achievable but remains contingent on addressing broader land-use conflicts and sources of adult mortality. Finally, I outline five interconnected research priorities—spanning cognitive ecology, trophic interactions, movement ecology, genomics, and formal comparative analyses—that would move shrike research from its current observational foundation toward a more experimental, mechanistic, and phylogenetically informed programme. By reframing shrikes as a model taxon for solitary living, this review aims to integrate avian behavioral ecology into broader comparative frameworks of social organization, cognition, and resilience under global change. Full article

Highly pathogenic avian influenza (HPAI) H5N1 clade 2.3.4.4b continues to circulate globally across wild birds, poultry, and an expanding range of mammalian hosts, highlighting the need for antiviral strategies that address the animal–environment–human interface. The influenza A polymerase acidic (PA) endonuclease, a key enzyme in viral transcription, represents a conserved antiviral target across host species. In this study, we present a computational prioritization framework integrating homology modeling, molecular docking, molecular dynamics simulations, and physicochemical filtering to identify candidate PA endonuclease inhibitors relevant to a One Health context. Homology models of contemporary H5N1 clade 2.3.4.4b PA sequences were constructed based on the crystallographic template 6FS8 and used for cross-host docking against a targeted ligand library. Docking analysis identified baloxavir, a reference inhibitor, and entecavir, a nucleoside analog, as compounds of interest, with entecavir demonstrating favorable binding behavior, particularly in the poultry-associated model. Molecular dynamics simulations of the poultry PA–entecavir complex indicated stable interaction over 170 ns, supported by low structural deviation and favorable binding free energy (ΔG ≈ −85 kJ/mol). Physicochemical profiling suggested that entecavir possesses properties such as high polarity and predicted aqueous solubility, which were considered within the translational filtering step of this computational workflow. However, these properties do not establish antiviral efficacy or practical suitability for field use. The study provides a structured framework for integrating cross-host structural analysis with basic translational considerations, supporting the identification of candidate compounds for further biochemical and virological evaluation within the context of H5N1 control. Full article

Birds serve as the primary natural reservoirs for avian influenza viruses (AIVs), harboring nearly all known AIV subtypes. The seasonal migratory movements of wild birds play a significant role in the transmission and dissemination of AIVs. Jianhu Lake in Dali, Yunnan Province, serves as a vital congregation point along avian migratory routes, providing an ideal habitat for birds. In this study, a total of 619 avian samples were collected from the Jianhu area, from which four H6N2 subtype AIV strains were successfully isolated. Among these, A/grey heron/Jianhu/JH-89/2024 (hereafter referred to as JH-89) and A/grey heron/Jianhu/JH-91/2024 (JH-91) were isolated from grey herons (Ardea cinerea); A/mareca penelope/Jianhu/JH-2-11/2025 (JH-2-11) from a Eurasian wigeon (Mareca penelope); and A/duck/Jianhu/JH-1-1/2025 (JH-1-1) from a domestic duck (Anas platyrhynchos domesticus). Genomic analyses revealed that these four H6N2 isolates belong to the Eurasian lineage, with all eight gene segments originating from complex reassortment events among diverse Asian isolates. In vitro assays demonstrated that the representative strain JH-2-11 replicated efficiently in various human- and animal-derived cell lines. In vivo infection models revealed that, without prior adaptation, the JH-2-11 strain successfully infected BALB/c mice, resulting in suppressed body weight gain and severe pathological lesions in the respiratory tract (nasal turbinates, trachea, and lungs), without causing mortality or extrapulmonary dissemination. Collectively, although these H6N2 viruses evolve primarily within avian hosts, they exhibit potential for mammalian adaptation and require continuous epidemiological monitoring. Full article

Multidrug-resistant (MDR) Salmonella enteritidis infections cause high mortality and devastating economic losses in poultry, pose severe threats to animal health and food safety, and create an urgent demand for effective antibiotic alternatives. Herein, we developed a cationic liposome-encapsulated bacteriophage endolysin Lys40 (designated Lys40-Lip), and systematically evaluated its therapeutic efficacy in a chick model challenged with Salmonella enteritidis strain S4. Recombinant Lys40 was encapsulated into cationic liposomes with an encapsulation efficiency (EE) of 34.83%. The resulting Lys40-Lip nanoparticles had a hydrodynamic diameter of 137.3 ± 4.1 nm, a high positive zeta potential of +42.5 ± 0.3 mV, and excellent stability, retaining 78.52% of its initial bactericidal activity after 56 days of storage at 4 °C. Following a three-day oral treatment in Salmonella enteritidis S4-infected chicks, Lys40-Lip significantly increased survival rates in a dose-dependent manner (72.22% to 88.89% for low-to-high dose vs. 44.44% in infected controls, p < 0.05) and reduced ileal Salmonella enteritidis S4 colonization by 28.8% compared to free Lys40. Histopathology revealed Lys40-Lip restored duodenal villus integrity and reduced jejunal and ileal inflammation. Serum cytokine analysis confirmed that Lys40-Lip effectively regulated the host inflammatory response, significantly downregulating the pro-inflammatory cytokines IL-1β and IL-6, and upregulating the anti-inflammatory cytokine IL-10. Crucially, liposomal encapsulation overcame the outer membrane barrier of Gram-negative bacteria via charge-driven fusion mediated by its high positive surface potential (+42.5 ± 0.3 mV), enabling targeted delivery of Lys40 without the need for EDTA or other outer membrane permeabilizers. Lys40-Lip significantly improved the therapeutic outcomes of avian salmonellosis via synergistic direct bactericidal activity, intestinal barrier protection and inflammatory response regulation, offering a promising nanotherapeutic strategy for the control of this disease in veterinary practice. Full article

Currently, the B-cell response patterns induced by viral antigens in avian disease models and their detailed immunological characteristics still require comprehensive elucidation at the single-cell level. In this study, we employed single-cell sequencing (scRNA-seq) and B cell library technology to conduct an in-depth analysis of B cells in the spleens of mice with inactivated duck hepatitis A virus type 1 (DHAV-1) as model antigen. This study aimed to investigate the immunological characteristics of the virus antigen in the mouse model and characteristics of B-Cell Receptors. The results showed that the DHAV-1 group had distinct changes in splenic B cell subset counts, proportions, and intercellular communication. Additionally, an increased trend in communication strength between Gm26917+B and Gm11837+B cells was observed, with enriched expression of C-X-C motif chemokine ligand (CXCL) and lymphotoxin (LT) detected in the DHAV-1 group. Furthermore, the DHAV-1 group exhibited a prominent combination of the IGHV1 family and IGHV3-1/IGHJ3 in the heavy (H) chain variable region. Compared with the CK group (negative control group), the amino acid sequence length and diversity of the CDR3 region in the DHAV-1 group exhibited a decreasing trend. In summary, our findings characterize the immunological features of splenic B cells in mice after immunization with inactivated DHAV-1, and provide a preliminary characterization of DHAV-1-induced B cell transcriptional states and BCR repertoire features, generating testable hypotheses for subsequent mechanistic investigations of B cell-mediated immune responses to viral antigens. Full article

The increasing prevalence of multidrug-resistant (MDR) pathogens, particularly avian pathogenic Escherichia coli (APEC) and methicillin-resistant Staphylococcus aureus (MRSA), poses a severe threat to the breeding industry and human health. To develop novel antibiotic alternatives, we adopted a “converting virulence into therapy” strategy by leveraging the type VI secretion system (T6SS) of the APEC strain ACN17-20. Guided by the structural analysis of T6SS Protein 00145, we rationally designed a series of amphipathic α-helical polypeptides. Among them, polypeptide A7 emerged as a lead candidate, exhibiting potent broad-spectrum antibacterial activity with negligible cytotoxicity against mammalian cells. Mechanistic studies revealed that A7 exerts a rapid bactericidal effect through a dual mode of action: physical disruption of bacterial membrane integrity leading to cytoplasmic leakage, and induction of lethal oxidative stress via reactive oxygen species (ROS) accumulation. Furthermore, A7 demonstrated excellent efficacy in eradicating pre-formed bacterial biofilms, addressing the challenge of persistent infections in breeding environments. In a mouse sepsis model induced by APEC and MRSA, A7 treatment significantly improved survival rates (60–80%), reduced bacterial loads in vital organs, and attenuated the systemic cytokine storm (TNF-α and IL-1β), thereby alleviating immune-mediated tissue damage. In conclusion, this study identifies polypeptide A7 as a safe therapeutic agent with a dual mechanism of action, providing a promising strategy to combat MDR infections and reduce antibiotic dependence. Full article

Highly pathogenic avian influenza virus (HPAIV) H5N1 has been detected in dairy cattle in the United States, with high viral loads observed in milk from infected animals. This raises public health concerns regarding potential transmission through exposure to raw milk. The sale of raw milk via vending machines represents a well-established distribution model in many European countries, including Switzerland. Although a notice must be posted on these milk vending machines stating that it is raw milk, together with appropriate processing instructions (heating to over 70 °C required, storage below 5 °C, consumption within 3 days), these notices are sometimes missing, and consumers often do not follow these guidelines. Over a four-month period, spanning from June 2025 to September 2025, 124 raw milk samples were collected from vending machines across Switzerland. Samples were screened for influenza A using reverse-transcription quantitative PCR (RT-qPCR). No samples tested positive for influenza A virus. The data from this study demonstrate the feasibility of implementing a sampling and detection system for HPAIV H5N1 in direct-to consumer raw milk samples and highlight the currently very low risk of HPAIV in raw milk samples sold via vending machines in Switzerland. Full article

The preservation of rooster semen quality during short-term liquid storage remains a challenge in poultry reproductive biotechnology because sperm cells rapidly lose functional competence under ambient conditions. This deterioration is largely associated with oxidative stress and lipid peroxidation of sperm membranes, which are particularly vulnerable in avian species due to their high polyunsaturated fatty acid content and limited cytoplasmic antioxidant defenses. Selenium is an essential trace element involved in cellular antioxidant protection through its incorporation into several selenoproteins that regulate redox balance and protect cellular structures from oxidative injury. The present study evaluated the effects of selenium methionine supplementation on rooster semen quality during liquid storage at 25 °C. Semen was diluted using a standard poultry semen extender composed of sodium glutamate, glucose, potassium acetate, magnesium acetate, and potassium citrate. Selenium methionine was incorporated into the semen extender at concentrations of 0.5%, 1%, and 2% (w/v) at the time of semen dilution prior to storage. Semen quality was assessed at 0, 4, 8, 12, and 24 h of storage. Functional parameters, including total sperm motility, sperm viability, and dead sperm percentage, together with kinematic variables (VSL, VCL, VAP, ALH, LIN, and STR), were analyzed using computer-assisted sperm analysis (CASA). Structural integrity was evaluated through acrosome and plasma membrane integrity tests, while sperm physiological status and apoptotic progression were assessed using Annexin V-FITC/propidium iodide flow cytometry. Significant effects of storage time, selenium methionine concentration, and their interaction were observed for multiple semen quality parameters (p < 0.05). Among the tested concentrations, supplementation with 0.5% selenium methionine consistently produced the most favorable results, maintaining higher sperm motility, viability, and membrane integrity while reducing dead sperm percentage and apoptotic progression during storage, with protective effects particularly evident at 8, 12, and 24 h compared with the control and higher concentrations. Polynomial contrast analysis indicated predominantly non-linear dose–response relationships, with quadratic and cubic components providing the best model fit (R² = 0.90–0.99; p < 0.0001), suggesting a hormetic antioxidant effect. Overall, these findings indicate that selenium methionine supplementation in semen extender improves the stability of rooster semen during short-term liquid storage at ambient temperature, with 0.5% showing the most consistent protective effects among the concentrations evaluated. Full article

The use of agro-industrial waste to obtain biochar has emerged as an environmentally friendly, low-cost, effective, profitable, and sustainable strategy for the removal of aflatoxin B1 (AFB1), a highly toxic and carcinogenic mycotoxin of importance in poultry production systems because it can cause serious economic losses, affect hatchability, egg production, and the growth of birds, and can cause their death. In this sense, the objective of the present study was to obtain a sustainable and low-cost biochar derived from agro-industrial coconut shell waste (BCS) and evaluate its AFB1 adsorption capacity using a conventional method based on buffer solutions and an in vitro avian digestion model that simulates the conditions of the gastrointestinal tract of the broiler chicken. The results showed that the adsorption capacity of BCS on AFB1 (250 ng/mL) at both pH 5.0 and 1.2 was close to 100%, while at pH 6.8, the adsorption of AFB1 was 86.24%. However, in the in vitro avian digestibility model, the adsorption capacity of BSC on AFB1 was 32.96%, thus highlighting the importance of considering factors that can affect the adsorption capacity of materials before in vivo studies, as this can lead to overestimations of results and, therefore, ineffective treatments or unexpected results in animals. Full article

Urban wetlands are acoustic hotspots where vegetation structure, hydrological dynamics, and anthropogenic noise interact, yet multi-season assessments of how vegetation influences avian soundscapes are limited. This study explored bird soundscape dynamics across forest, open forest grassland, and meadow habitats in Nanjing Xinjizhou National Wetland Park, eastern China, using passive acoustic monitoring during spring and autumn 2023. Twelve sampling points (four per vegetation type) were established, and six acoustic indices were calculated, including the Acoustic Complexity Index (ACI), Acoustic Diversity Index (ADI), Acoustic Evenness Index (AEI), Bioacoustic Index (BIO), Normalized Difference Soundscape Index (NDSI), and Acoustic Entropy Index (H). were calculated from 48-h recordings each season. Random forest models and redundancy analysis assessed the relationships between acoustic indices, fine-scale vegetation parameters (e.g., crown width, tree height, species richness), and anthropogenic factors (e.g., distance to roads/trails, surface hardness). Vegetation structure, particularly crown width, was the primary driver of avian acoustic diversity, with broad-crowned forests consistently exhibiting the highest acoustic complexity. In spring, anthropogenic factors such as trail and road proximity dominated soundscape variation, suppressing biological sounds. In autumn, with reduced human presence, vegetation structure emerged as the dominant factor, while bioacoustic activity remained elevated despite reduced peaks in acoustic complexity. Proximity to roads increased low-frequency (1–2 kHz) noise and suppressed mid-frequency (4–8 kHz) bird vocalizations, but trees with crown widths ≥4 m maintained higher acoustic diversity even near disturbance sources. This study demonstrates that vegetation structure mediates both resource availability and sound propagation, buffering the effects of anthropogenic disturbance in frequency-specific ways. Multi-season sampling is crucial for understanding the dynamic interplay between vegetation phenology and human activity that shapes urban wetland soundscapes. Full article

Radar plays a pivotal role throughout the entire Counter-Unmanned Aerial Vehicle (C-UAV) process, and there is an urgent need for radar technologies capable of effectively detecting and recognizing non-cooperative Unmanned Aerial Vehicles (UAVs). However, the commonly emphasized UAV True Positive Ratio (TPR) fails to adequately reflect radar performance in environments with high bird density. Frequent bird activity leads to numerous false UAV alarms and unreliable recognition results. To address this issue, this paper introduces the concept of UAV Recognition Confidence (URC), a comprehensive metric that quantifies the credibility of UAV recognition by jointly considering recognition performance indicators and environmental factors. Simulations and field measurements employ a bird random walk model and real-time trajectory statistics to represent the dynamic population variations of birds. Both simulation and X-band radar experimental results verify that the proposed URC framework can effectively characterize the recognition capability of radar systems by capturing the complex interactions between the UAV and surrounding avian activities. Full article

Ducks, once considered mere reservoirs, now serve as both victims and amplifiers of persistent highly pathogenic avian influenza (HPAI) virus cycles in wild populations. The molecular pathogenesis of HPAI is shaped by complex, dysregulated molecular networks, necessitating a systems biology approach that integrates computational modeling of host–pathogen interactions. Despite recent advances, a comprehensive understanding of the signaling pathways, molecular mechanisms, and hub genes driving HPAI H5N1 pathogenesis in avian hosts remains incomplete. This study addresses this gap by employing an integrated multi-omics strategy—combining transcriptomic, proteomic, and phosphoproteomic analyses—to map the signaling networks and key host factors involved in HPAI H5N1 infection in duck lung tissue. Our network analysis revealed activation of RIG-I-like receptor, toll-like receptor, NOD-like receptor, NF-κB, and JAK/STAT signaling pathways. Phosphoproteomic profiling independently confirmed the activation of these pathways, supporting the integrated network findings. Key regulatory hub genes identified include STAT1, DDX58 (RIG-I), MYD88, NFKBIA, NFKB1, IRF7, SOCS3, ACTB, TLR4, TLR7, IL-6, CASP1, and CASP8, which form a central hub in duck antiviral immunity. Some of these genes may represent promising targets for therapeutic or vaccine development against avian influenza. Collectively, this work delineates the critical signaling pathways and hub genes underlying HPAI H5N1 pathogenesis in ducks through comprehensive multi-omics integration. Full article

Avian reovirus (ARV) is a ubiquitous pathogen in commercial poultry, traditionally associated with viral arthritis, malabsorption syndrome, and growth retardation. In recent years, the rapid genetic diversification of ARV has raised increasing concerns regarding vaccine mismatch, immune dysregulation, and complex disease outcomes in vaccinated flocks. In this study, an integrated investigation combining large-scale field surveillance, molecular characterization, and controlled animal experiments was conducted to elucidate the epidemiological features of ARV and its impact on heterologous vaccine-induced protection. Epidemiological surveillance revealed widespread ARV circulation in commercial poultry flocks, with marked genetic divergence between contemporary field isolates and classical vaccine strains. Phylogenetic analysis based on the σC gene demonstrated that the majority of circulating strains clustered within emerging genotypes that were genetically distinct from vaccine-related lineages. Using a controlled infection–vaccination–challenge model, prior ARV infection was shown to significantly impair humoral immune responses induced by an inactivated Aviadenovirus hydropericardii (fowl adenovirus serotype 4, FAdV-4) vaccine, as evidenced by reduced FAdV-4-specific antibody levels. Importantly, ARV pre-infection compromised vaccine-mediated protection and was associated with enhanced FAdV-4 pathogenicity following challenge, resulting in increased mortality, aggravated clinical manifestations, and more pronounced pathological lesions. These findings indicate that prior ARV infection is associated with reduced FAdV-4 vaccine-induced humoral responses and partial loss of protective efficacy under controlled experimental conditions. Importantly, this study provides quantitative experimental evidence using a defined infection–vaccination–challenge interference model rather than proposing a previously unrecognized virus-virus interaction. These results underscore the necessity of enhanced ARV surveillance and optimized immunization strategies in modern poultry production systems. Full article