Development and evaluation of a chicken embryo fibroblast cell culture based live attenuated Indian strain duck plague vaccine.

Duck plague (DP) is an acute, contagious and fatal disease, caused by duck enteritis virus (DEV), with worldwide distribution causing several outbreaks and posing severe economic losses. The present study was carried out with a goal of development of a live attenuated cell culture based DP vaccine using an Indian strain of DEV and evaluation of its safety, efficacy along with complete genome analysis. The live attenuated DP vaccine (DPvac/IVRI-19) was developed by serial propagation of a virulent isolate of DEV (DEV/India/IVRI-2016) in the chicken embryo fibroblast (CEF) primary cell culture. Adaptation of DEV in CEF cell culture was indicated by more rapid appearance of cytopathic effects (CPE) and gradual increase of virus titre, which reached up to 107.5 TCID50/mL after 41 passages. The safety, immunogenicity and efficacy of the vaccine were determined by immunization trials in ducklings. The DPvac/IVRI-19 was found to be avirulent and completely safe in the ducklings. Further, the vaccine induced both humoral and cell mediated immune responses and afforded 100% protection against the virulent DEV challenge. A comparison of the whole genome of DPvac/IVRI-19 (MZ911871) and DEV/India/IVRI-2016 (MZ824102) revealed significant number of mutations, which might be associated with viral attenuation. Phylogenetic tree of DEV/India/IVRI-2016 revealed its evolutionary relationship with other DEV isolates, but it formed a separate cluster with certain unique mutations. Thus, with the proven safety and 100% efficacy, the DPvac/IVRI-19 is suitable for large scale production with precisely pure form of vaccine and has potential utility at national and global levels.

Fluctuation of flavor quality in roasted duck: The consequences of raw duck preform's repetitive freeze-thawing.

This study aimed to investigate the changes in flavor quality of roasted duck during repetitive freeze-thawing (FT, -20 ℃ for 24 h, then at 4 ℃ for 24 h for five cycles) of raw duck preforms. HS-SPME/GC-MS analysis showed that more than thirty volatile flavor compounds identified in roasted ducks fluctuated with freeze-thawing of raw duck preforms, while hexanal, nonanal, 1-octen-3-ol, and acetone could as potential flavor markers. Compared with the unfrozen raw duck preforms (FT-0), repetitive freeze-thawing increased the protein/lipid oxidation and cross-linking of raw duck preforms by maintaining the higher carbonyl contents (1.40 âˆ¼ 3.30 nmol/mg), 2-thiobarbituric acid reactive substances (0.25 âˆ¼ 0.51 mg/kg), schiff bases and disulfide bond (19.65 âˆ¼ 30.65 µmol/g), but lower total sulfhydryl (73.37 âˆ¼ 88.94 µmol/g) and tryptophan fluorescence intensity. Moreover, A lower protein band intensity and a transformation from α-helixes to ß-sheets and random coils were observed in FT-3 âˆ¼ FT-5. The obtained results indicated that multiple freeze-thawing (more than two cycles) of raw duck preforms could be detrimental to the flavor quality of the roasted duck due to excessive oxidation and degradation.

Feather corticosterone is lower in translocated and historical populations of the endangered Laysan duck (Anas laysanensis).

Identifying reliable bioindicators of population status is a central goal of conservation physiology. Physiological stress measures are often used as metrics of individual health and can assist in managing endangered species if linked to fitness traits. We analysed feather corticosterone, a cumulative physiological stress metric, of individuals from historical, translocated, and source populations of an endangered endemic Hawaiian bird, the Laysan duck (Anas laysanensis). We hypothesized that feather corticosterone would reflect the improved reproduction and survival rates observed in populations translocated to Midway and Kure Atolls from Laysan Island. We also predicted less physiological stress in historical Laysan birds collected before ecological conditions deteriorated and the population bottleneck. All hypotheses were supported: we found lower feather corticosterone in the translocated populations and historical samples than in those from recent Laysan samples. This suggests that current Laysan birds are experiencing greater physiological stress than historical Laysan and recently translocated birds. Our initial analysis suggests that feather corticosterone may be an indicator of population status and could be used as a non-invasive physiological monitoring tool for this species with further validation. Furthermore, these preliminary results, combined with published demographic data, suggest that current Laysan conditions may not be optimal for this species.

First molecular insights into gastrointestinal helminths of domestic birds in the Caspian Sea Littoral of Iran with an emphasis on the One Health concern.

The current investigation was carried out during the period from July 2022 to March 2023, aiming to investigate the prevalence of gastrointestinal helminths in domestic birds collected from traditional markets in Guilan province. One hundred forty-eight domestic birds, including chickens (Gallus gallus domesticus), domestic ducks (Anas platyrhynchos domesticus), greylag geese (Anser anser), and domestic turkeys (Meleagris gallopavo domesticus) were examined. Totally, 42.56% of the investigated birds were positive for helminthic parasites. Morphological analysis revealed varying infection rates among birds: Echinostoma revolutum (5.40%), Hypoderaeum conoideum (2.02%), Cloacotaenia megalops (0.67%), Hymenolepididae family (4.05%), Ascaridia galli (16.89%), and Heterakis gallinarum (4.72%). The investigation involved molecular analysis of the 18S and ITS1 + 5.8S + ITS2 rRNA gene regions. The findings indicated that the 18S region of nematode isolates exhibited a similarity of 92 to 100% with sequences in the GenBank, whereas trematode and cestode isolates showed a gene similarity ranging from 88 to 99%. The ITS regions of nematode, trematode, and cestode isolates exhibited genetic similarities ranging from 87 to 100%, 73-99%, and 75-99%, respectively. Furthermore, phylogenetic analysis confirmed the categorization of the identified species within the Ascaridiidae, Heterakidae, Hymenolepididae, and Echinostomatidae families, indicating their close affinity with previously documented species. Implementing precise control measures such as consistent monitoring, adequate sanitation protocols, and administering anthelmintic treatments is crucial for effectively managing parasitic infections in free-range and backyard poultry farms. Additionally, conducting further surveys is advisable to assess the impact of these parasites on the health and productivity of poultry in the investigated area.

The novel probiotic preparation based on Lactobacillus spp. mixture on the intestinal bacterial community structure of Cherry Valley duck.

The development and utilization of probiotics have many environmental benefits when they are used to replace antibiotics in animal production. In this study, intestinal lactic acid bacteria were isolated from the intestines of Cherry Valley ducks. Probiotic lactic acid bacterial strains were screened for antibacterial activity and tolerance to produce a Lactobacillus spp. mixture. The effects of the compound on the growth performance and intestinal flora of Cherry Valley ducks were studied. Based on the results of the antibacterial activity and tolerance tests, the highly active strains Lactobacillus casei 1.2435, L. salivarius L621, and L. salivarius L4 from the intestines of Cherry Valley ducks were selected. The optimum ratio of L. casei 1.2435, L. salivarius L621, and L. salivarius L4 was 1:1:2, the amount of inoculum used was 1%, and the fermentation time was 14 h. In vivo experiments showed that compared with the control group, the relative abundances of intestinal Lactobacillus and Blautia were significantly increased in the experimental group fed the lactobacilli compound (P < 0.05); the relative abundances of Parabacteroides, [Ruminococcus]_torques_group, and Enterococcus were significantly reduced (P < 0.05), and the growth and development of the dominant intestinal flora were promoted in the Cherry Valley ducks. This study will provide more opportunities for Cherry Valley ducks to choose microecological agents for green and healthy breeding.

Repeatability and reproducibility of hunter-harvest sampling for avian influenza virus surveillance in Great Britain.

Emerging pathogens can threaten human and animal health, necessitating reliable surveillance schemes to enable preparedness. We evaluated the repeatability and reproducibility of a method developed previously during a single year at one study site. Hunter-harvested ducks and geese were sampled for avian influenza virus at three discrete locations in the UK. H5N1 highly pathogenic avian influenza (HPAIV) was detected in four species (mallard [Anas platyrhynchos], Eurasian teal [Anas crecca], Eurasian wigeon [Mareca penelope] and pink-footed goose [Anser brachyrhynchus]) across all three locations and two non-HPAIV H5N1, influenza A positive detections were made from a mallard and Eurasian wigeon at two locations. Virus was detected within 1-to-4 days of sampling at every location. Application of rapid diagnostic methods to samples collected from hunter-harvested waterfowl offers potential as an early warning system for the surveillance and monitoring of emerging and existing strains of avian influenza A viruses in key avian species.

HSP70 positively regulates translation by interacting with the IRES and stabilizes the viral structural proteins VP1 and VP3 to facilitate duck hepatitis A virus type 1 replication.

The maintenance of viral protein homeostasis depends on the interaction between host cell proteins and viral proteins. As a molecular chaperone, heat shock protein 70 (HSP70) has been shown to play an important role in viral infection. Our results showed that HSP70 can affect translation, replication, assembly, and release during the life cycle of duck hepatitis A virus type 1 (DHAV-1). We demonstrated that HSP70 can regulate viral translation by interacting with the DHAV-1 internal ribosome entry site (IRES). In addition, HSP70 interacts with the viral capsid proteins VP1 and VP3 and promotes their stability by inhibiting proteasomal degradation, thereby facilitating the assembly of DHAV-1 virions. This study demonstrates the specific role of HSP70 in regulating DHAV-1 replication, which are helpful for understanding the pathogenesis of DHAV-1 infection and provide additional information about the role of HSP70 in infection by different kinds of picornaviruses, as well as the interaction between picornaviruses and host cells.

Genome-wide association analysis explores the genetic loci of amino acid content in duck's breast muscle.

BACKGROUND: Amino acids are the basic components of protein and an important index to evaluate meat quality. With the rapid development of genomics, candidate regions and genes affecting amino acid content in livestock and poultry have been gradually revealed. Hence, genome-wide association study (GWAS) can be used to screen candidate loci associated with amino acid content in duck meat. RESULT: In the current study, the content of 16 amino acids was detected in 358 duck breast muscles. The proportion of Glu to the total amino acid content was relatively high, and the proportion was 0.14. However, the proportion of Met content was relatively low, at just 0.03. By comparative analysis, significant differences were found between males and females in 3 amino acids, including Ser, Met, and Phe. In addition, 12 SNPs were significantly correlated with Pro content by GWAS analysis, and these SNPs were annotated by 7 protein-coding genes; 8 significant SNPs were associated with Tyr content, and these SNPs were annotated by 6 protein-coding genes. At the same time, linkage disequilibrium (LD) analysis was performed on these regions with significant signals. The results showed that three SNPs in the 55-56 Mbp region of chromosome 3 were highly correlated with the leader SNP (chr3:55526954) that affected Pro content (r2 > 0.6). Similarly, LD analysis showed that there were three SNPs in the 21.2-21.6 Mbp region of chromosome 13, which were highly correlated with leader SNP (chr13:21421661) (r2 > 0.6). Moreover, Through functional enrichment analysis of all candidate genes. The results of GO enrichment analysis showed that several significant GO items were associated with amino acid transport function, including amino acid transmembrane transport and glutamine transport. The results further indicate that these candidate genes are closely associated with amino acid transport. Among them, key candidate genes include SLC38A1. For KEGG enrichment analysis, CACNA2D3 and CACNA1D genes were covered by significant pathways. CONCLUSION: In this study, GWAS analysis found a total of 28 significant SNPs affecting amino acid content. Through gene annotation, a total of 20 candidate genes were screened. In addition, Through LD analysis and enrichment analysis, we considered that SERAC1, CACNA2D3 and SLC38A1 genes are important candidate genes affecting amino acid content in duck breast muscle.

Genome analysis of gyroviruses identified in waterfowl in Arizona (USA).

Gyroviruses are small single-stranded DNA (ssDNA) viruses that are largely associated with birds. Chicken anemia virus is the most extensively studied gyrovirus due to its disease impact on the poultry industry. However, we know much less about gyroviruses infecting other avian species. To investigate gyroviruses infecting waterfowl, we determined six complete genome sequences that fall into three gyrovirus groups, referred to as waterfowl gyrovirus 1 (n = 3), 2 (n = 2), and 3 (n = 1), in organs from hunter-harvested waterfowl from Arizona (USA). The waterfowl gyrovirus 1 variants were identified in multiple organs of a single American wigeon and represent a tentative new species. The waterfowl gyrovirus 2 variants were identified in the livers of two American wigeons and share >70% VP1 nucleotide sequence identity with gyrovirus 9, previously identified in the spleen of a Brazilian Pekin duck (MT318123) and a human fecal sample (KP742975). Waterfowl gyrovirus 3 was identified in a northern pintail spleen sample, and it shares >73% VP1 nucleotide sequence identity with two gyrovirus 13 sequences previously identified in Brazilian Pekin duck spleens (MT318125 and MT318127). These gyroviruses are the first to be identified in waterfowl in North America, as well as in American wigeons and northern pintails.

E-M349E and NS2A/2B-P1(T) are compensatory mutations of rDTMUV-NS2AB-P1P1'(AA), which regain virus proliferation by enhancing the virus package and restoring NS2A/2B cleavage.

Duck Tembusu virus (DTMUV) belongs to the Flaviviridae family and mainly infects ducks. The genome of DTMUV is translated into a polyprotein, which is further cleaved into several protein by viral NS2B3 protease and host proteases. Crucially, the cleavage of the NS2A/2B precursor during this process is essential for the formation of replication complexes and viral packaging. Previous research has demonstrated that alanine mutations in NS2A/2B (P1P1' (AA)) result in an attenuated strain (rDTMUV-NS2A/2B-P1P1' (AA)) by disrupting NS2A/2B cleavage. In this study, we investigate the effects of the P1P1' (AA) mutation on the viral life cycle and explore compensatory mutations in rDTMUV-NS2A/2B-P1P1' (AA). Infected ducklings exhibit similar body weight gain and viral tissue loads to DTMUV-WT. Compensatory mutations E-M349E and P1(T) emerge, restoring proliferation levels to those of rDTMUV-WT. Specifically, E-M349E enhances viral packaging, while P1(T) reinstates NS2A/2B proteolysis in vitro. Thus, our findings reveal novel compensatory sites capable of restoring the attenuated DTMUV during polyprotein cleavage and packaging.

Whole-genome sequences restore the original classification of dabbling ducks (genus Anas).

Anas, is a genus of dabbling ducks and encompasses a considerable number of species, among which some are the progenitors of domestic ducks. However, the taxonomic position of the Anas genus remains uncertain because several of its species, initially categorized as Anas based on morphological characteristics, were subsequently reclassified and grouped with the South American genus Tachyeres, primarily based on analysis of their mitochondrial gene sequences. Here, we constructed a phylogenetic tree using nine of our recently assembled Anas genomes, two Tachyeres genomes, and one Cairina genome that are publicly available. The results showed that the Northern shoveler (Anas clypeata) and Baikal teal (Anas formosa) clustered with the other Anas species at the whole-genome level rather than with the Steamer ducks (genus Tachyeres). Therefore, we propose to restore the original classification of the Anas genus, which includes the Northern shoveler and Baikal teal species, 47 species in total. Moreover, our study unveiled extensive incomplete lineage sorting and an ancient introgression event from Tachyeres to Anas, which has led to notable phylogenetic incongruence within the Anas genome. This ancient introgression event not only supports the theory that Anas originated in South America but also that it played a significant role in shaping the evolutionary trajectory of Anas, including the domestic duck.

DESCRIPTION OF FEMALE DENDRITOBILHARZIA PULVERULENTA (BRAUN, 1901) SKRJABIN, 1924 FROM TWO NEW AVIAN HOSTS IN NAMIBIA WITH PHYLOGENETIC ANALYSES AND COMMENTS ON SEVERAL TAXONOMICALLY UNCERTAIN AVIAN SCHISTOSOME SEQUENCES.

During a 2021 parasitological survey of birds in the Nyae Nyae-Khaudum Dispersal Area (Kavango-Zambezi Transfrontier Conservation Area, Namibia), we collected 9 specimens of Dendritobilharzia pulverulenta (Braun, 1901) Skrjabin, 1924 infecting the blood (heart lumen) of a white-backed duck, Thalassornis leuconotus (Eyton, 1838) (Anseriformes: Anatidae), and a fulvous whistling duck, Dendrocygna bicolor (Vieillot, 1816) (Anatidae). These flukes were fixed for morphology and preserved for DNA extraction. We assigned our specimens to DendritobilharziaSkrjabin and Zakharow, 1920 because they were strongly dorso-ventrally flattened in both sexes and had an intestinal cyclocoel with a zig-zag common cecum with lateral dendritic ramifications, numerous testes posterior to the cyclocoel and flanking the dendritic ramifications, and a tightly compacted convoluted ovary as well as lacking an oral sucker, ventral sucker, and gynaecophoric canal. Further, our specimens were morphologically identical to previously published descriptions of D. pulverulenta. Sequences of the 28S from our specimens were nearly identical to those identified as D. pulverulenta from North America (New Mexico), and our 28S phylogenetic analysis recovered D. pulverulenta within a polytomy of other Gigantobilharziinae spp. The CO1 phylogenetic analysis recovered a monophyletic Dendritobilharzia and, with low taxon sampling, a monophyletic Gigantobilharzia. This is the first record of a species of Dendritobilharzia infecting these ducks as well as the first record of an adult Dendritobilharzia from sub-Saharan Africa. The original description of adult D. pulverulenta (type locality: northern Sudan) was based on 2 males only, and hence the present study is the first description of female D. pulverulenta from Africa (the continent of the type locality). We reassign 2 Gigantobilharziinae spp. based on morphology and nucleotide evidence: Gigantobilharzia ensenadense (Lorenti, Brant, Gilardoni, Diaz, and Cremonte, 2022) Dutton and Bullard, n. comb., and Gigantobilharzia patagonense (Lorenti, Brant, Gilardoni, Diaz, and Cremonte, 2022) Dutton and Bullard, n. comb. We also comment on several avian schistosome sequences whose identities need confirmation or that likely have been misidentified.

Co-exposure to PVC microplastics and cadmium induces oxidative stress and fibrosis in duck pancreas.

PVC microplastics (PVC-MPs) are environmental pollutants that interact with cadmium (Cd) to exert various biological effects. Ducks belong to the waterfowl family of birds and therefore are at a higher risk of exposure to PVC-MPs and Cd than other animals. However, the effects of co-exposure of ducks to Cd and PVC-MPs are poorly understood. Here, we used Muscovy ducks to establish an in vivo model to explore the effects of co-exposure to 1 mg/L PVC-MPs and 50 mg/kg Cd on duck pancreas. After 2 months of treatment with 50 mg/kg Cd, pancreas weight decreased by 21 %, and the content of amylase and lipase increased by 25 % and 233 %. However, exposure to PVC-MPs did not significantly affect the pancreas. Moreover, co-exposure to PVC-MPs and Cd worsened the reduction of pancreas weight and disruption of pancreas function compared to exposure to either substance alone. Furthermore, our research has revealed that exposure to PVC-MPs or Cd disrupted mitochondrial structure, reduced ATP levels by 10 % and 18 %, inhibited antioxidant enzyme activity, and increased malondialdehyde levels by 153.8 % and 232.5 %. It was found that exposure to either PVC-MPs or Cd can induce inflammation and fibrosis in the duck pancreas. Notably, co-exposure to PVC-MPs and Cd exacerbated inflammation and fibrosis, with the content of IL-1, IL-6, and TNF-α increasing by 169 %, 199 %, and 98 %, compared to Cd exposure alone. The study emphasizes the significance of comprehending the potential hazards linked to exposure to these substances. In conclusion, it presents promising preliminary evidence that PVC-MPs accumulate in duck pancreas, and increase the accumulation of Cd. Co-exposure to PVC-MPs and Cd disrupts the structure and function of mitochondria and promotes the development of pancreas inflammation and fibrosis.

Occludin and collagen IV degradation mediated by the T9SS effector SspA contributes to blood-brain barrier damage in ducks during Riemerella anatipestifer infection.

Riemerella anatipestifer infection is characterized by meningitis with neurological symptoms in ducklings and has adversely affected the poultry industry. R. anatipestifer strains can invade the duck brain to cause meningitis and neurological symptoms, but the underlying mechanism remains unknown. In this study, we showed that obvious clinical symptoms, an increase in blood‒brain barrier (BBB) permeability, and the accumulation of inflammatory cytokines occurred after intravenous infection with the Yb2 strain but not the mutant strain Yb2ΔsspA, indicating that Yb2 infection can lead to cerebrovascular dysfunction and that the type IX secretion system (T9SS) effector SspA plays a critical role in this pathological process. In addition, we showed that Yb2 infection led to rapid degradation of occludin (a tight junction protein) and collagen IV (a basement membrane protein), which contributed to endothelial barrier disruption. The interaction between SspA and occludin was confirmed by coimmunoprecipitation. Furthermore, we found that SspA was the main enzyme mediating occludin and collagen IV degradation. These data indicate that R. anatipestifer SspA mediates occludin and collagen IV degradation, which functions in BBB disruption in R. anatipestifer-infected ducks. These findings establish the molecular mechanisms by which R. anatipestifer targets duckling endothelial cell junctions and provide new perspectives for the treatment and prevention of R. anatipestifer infection.

The impact of micropolymorphism in Anpl-UAA on structural stability and peptide presentation.

Micropolymorphism significantly shapes the peptide-binding characteristics of major histocompatibility complex class I (MHC-I) molecules, affecting the host's resistance to pathogens, which is particularly pronounced in avian species displaying the "minimal essential MHC" expression pattern. In this study, we compared two duck MHC-I alleles, Anpl-UAA*77 and Anpl-UAA*78, that exhibit markedly different peptide binding properties despite their high sequence homology. Through mutagenesis experiments and crystallographic analysis of complexes with the influenza virus-derived peptide AEAIIVAMV (AEV9), we identified a critical role for the residue at position 62 in regulating hydrogen-bonding interactions between the peptide backbone and the peptide-binding groove. This modulation affects the characteristics of the B pocket and the stability of the loop region between the 310 helix and the α1 helix, leading to significant changes in the structure and stability of the peptide-MHC-I complex (pMHC-I). Moreover, the proportion of different residues at position 62 among Anpl-UAAs may reflect the correlation between pAnpl-UAA stability and duck body temperature. This research not only advances our understanding of the Anpl-UAA structure but also deepens our insight into the impact of MHC-I micropolymorphism on peptide binding.

In Ovo Models to Predict Virulence of Highly Pathogenic Avian Influenza H5-Viruses for Chickens and Ducks.

Highly pathogenic avian influenza (HPAI) H5-viruses are circulating in wild birds and are repeatedly introduced to poultry causing outbreaks in the Netherlands since 2014. The largest epizootic ever recorded in Europe was caused by HPAI H5N1 clade 2.3.4.4b viruses in the period 2021-2022. The recent H5-clade 2.3.4.4 viruses were found to differ in their virulence for chickens and ducks. Viruses causing only mild disease may remain undetected, increasing the risk of virus spread to other farms, wild birds and mammals. We developed in ovo models to determine the virulence of HPAI viruses for chickens and ducks, which are fast and have low costs. The virulence of five contemporary H5-viruses was compared studying replication rate, average time to death and virus spread in the embryo. Remarkable differences in virulence were observed between H5-viruses and between poultry species. The H5N1-2021 virus was found to have a fast replication rate in both the chicken and duck in ovo models, but a slower systemic virus dissemination compared to three other H5-clade 2.3.4.4b viruses. The results show the potential of in ovo models to quickly determine the virulence of novel HPAI viruses, and study potential virulence factors which can help to better guide the surveillance in poultry.

Isolation and identification of multidrug resistance bacterial agents implicated in duck enteritis with first record of Salmonella enterica subspecies arizonae in Egypt.

Background: Bacterial infections causing digestive problems are among the most serious threats to Egypt's duck industry, owing to their effects on feed utilization and body weight gain. Aim: As a result, the goal of this study was to identify bacterial pathogens causing enteritis in ducks as well as testing their antimicrobials resistance capabilities. Methods: Forty-two duck flocks from different localities at four Egyptian Governorates (El-Sharkia, El-Gharbia, El-Dakahlia, and El-Qaliobia) have been subjected to clinical and postmortem examination as well as bacterial isolation and identification. The liver samples have been collected aseptically from freshly euthanized ducks for bacterial isolation followed by identification using conventional biochemical tests, VITEK 2 system, and confirmatory polymerase chain reaction (PCR) for detection of the uid A gene (beta-glucuronidase enzyme) of Escherichia coli. In addition, antimicrobial sensitivity testing for the isolates against different antimicrobials by the VITEK 2 system was used. Results: Forty-six positive bacterial isolates were identified using conventional methods and the VITEK 2 system including Staphylococcus spp. (52.17%), E. coli (41.30%), and 2.17% for each of Enterococcus casseli lavus, Salmonella enterica subspecies arizonae, and Enterobacter cloacae. PCR was positive for E. coli uid A gene at 556 bp. The antibiogram patterns of isolated pathogens from naturally infected ducks in our work demonstrated 87% multidrug resistance with varying results against different antimicrobial drugs tested. Such findings supported the fact of the upgrading multidrug resistance of Staphylococci and Enterobacteriacae. Conclusion: The most prevalent bacterial pathogens associated with duck enteritis were Staphylococcus spp. and E. coli with the first report of S. enterica subspecies arizonae causing duck enteritis in Egypt.

Lactobacillus acidophilus and Bacillus subtilis significantly change the growth performance, serum immunity and cecal microbiota of Cherry Valley ducks during the fattening period.

This study explored the effects of a Bacillus subtilis and Lactobacillus acidophilus mixture containing the co-fermented products of the two probiotics on growth performance, serum immunity and cecal microbiota of Cherry Valley ducks. This study included 480 one-day-old Cherry Valley ducks divided into four feeding groups: basal diet (control group) and basal diet supplemented with 300, 500, or 700 mg/kg of the probiotic powder; the ducks were raised for 42 days. Compared with the control group, body weight on day 42 and the average daily gain on days 15-42 significantly increased (p < 0.05), and the feed conversion rate significantly decreased (p < 0.05) in the experimental groups. Furthermore, the serum immunoglobulin (Ig) A, IgG, IgM, and interleukin (IL)-4 levels increased significantly (p < 0.05), and IL-1ß, IL-2, and tumor necrosis factor-α decreased significantly (p < 0.05) in the experimental groups. Finally, Sellimonas, Prevotellaceae NK3B31 group, Lachnospiraceae NK4A136 group and Butyricoccus played an important role in the cecal microbiota of the experimental group. Thus, the probiotic powder has impacts on the growth performance, serum immunity and cecal microbiota of Cherry Valley Ducks.

Impacts of longitudinal water curtain cooling system on transcriptome-related immunity in ducks.

BACKGROUND: The closed poultry houses integrated with a longitudinal water curtain cooling system (LWCCS) are widely used in modern poultry production. This study showed the variations in environmental conditions in closed houses integrated with a longitudinal water curtain cooling system. We evaluated the influence of different environmental conditions on duck growth performance and the transcriptome changes of immune organs, including the bursa of Fabricius and the spleen. RESULT: This study investigated the slaughter indicators and immune organ transcriptomes of 52-day-old Cherry Valley ducks by analyzing the LWCC at different locations (water curtain end, middle position, and fan cooling end). The results showed that the cooling effect of the LWCCS was more evident from 10:00 a.m. -14:00. And from the water curtain end to the fan cooling end, the hourly average temperature differently decreased by 0.310℃, 0.450℃, 0.480℃, 0.520℃, and 0.410℃, respectively (P < 0.05). The daily and hourly average relative humidity decreased from the water curtain end to the fan cooling end, dropping by 7.500% and 8.200%, respectively (P < 0.01). We also observed differences in production performance, such as dressing weight, half-eviscerated weight, skin fat rate, and percentage of abdominal fat (P < 0.01), which may have been caused by environmental conditions. RNA-sequencing (RNA-seq) revealed 211 and 279 differentially expressed genes (DEGs) in the ducks' bursa of Fabricius and spleen compared between the water curtain end and fan cooling end, respectively. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of the two organs showed the DEGs were mainly enriched in cytokine-cytokine receptor interaction, integral component of membrane, Retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs) signaling pathway, etc. Our results implied that full-closed poultry houses integrated with LWCCS could potentially alter micro-environments (water curtain vs. fan cooling), resulting in ducks experiencing various stressful situations that eventually affect their immunity and production performance. CONCLUSION: In this study, our results indicated that uneven distributions of longitudinal environmental factors caused by LWCCS would affect the dressed weight, breast muscle weight, skin fat rate, and other product performance. Moreover, the expression of immune-related genes in the spleen and bursa of ducks could be affected by the LWCCS. This provides a new reference to optimize the use of LWCCS in conjunction with close duck houses in practical production.

Integrating miRNA and full-length transcriptome profiling to elucidate the mechanism of muscle growth in Muscovy ducks reveals key roles for miR-301a-3p/ANKRD1.

BACKGROUND: The popularity of Muscovy ducks is attributed not only to their conformation traits but also to their slightly higher content of breast and leg meat, as well as their stronger-tasting meat compared to that of typical domestic ducks. However, there is a lack of comprehensive systematic research on the development of breast muscle in Muscovy ducks. In addition, since the number of skeletal muscle myofibers is established during the embryonic period, this study conducted a full-length transcriptome sequencing and microRNA sequencing of the breast muscle. Muscovy ducks at four developmental stages, namely Embryonic Day 21 (E21), Embryonic Day 27 (E27), Hatching Day (D0), and Post-hatching Day 7 (D7), were used to isolate total RNA for analysis. RESULTS: A total of 68,161 genes and 472 mature microRNAs were identified. In order to uncover deeper insights into the regulation of mRNA by miRNAs, we conducted an integration of the differentially expressed miRNAs (known as DEMs) with the differentially expressed genes (referred to as DEGs) across various developmental stages. This integration allowed us to make predictions regarding the interactions between miRNAs and mRNA. Through this analysis, we identified a total of 274 DEGs that may serve as potential targets for the 68 DEMs. In the predicted miRNA‒mRNA interaction networks, let-7b, miR-133a-3p, miR-301a-3p, and miR-338-3p were the hub miRNAs. In addition, multiple DEMs also showed predicted target relationships with the DEGs associated with skeletal system development. These identified DEGs and DEMs as well as their predicted interaction networks involved in the regulation of energy homeostasis and muscle development were most likely to play critical roles in facilitating the embryo-to-hatchling transition. A candidate miRNA, miR-301a-3p, exhibited increased expression during the differentiation of satellite cells and was downregulated in the breast muscle tissues of Muscovy ducks at E21 compared to E27. A dual-luciferase reporter assay suggested that the ANKRD1 gene, which encodes a transcription factor, is a direct target of miR-301a-3p. CONCLUSIONS: miR-301a-3p suppressed the posttranscriptional activity of ANKRD1, which is an activator of satellite cell proliferation, as determined with gain- and loss-of-function experiments. miR-301a-3p functions as an inducer of myogenesis by targeting the ANKRD1 gene in Muscovy ducks. These results provide novel insights into the early developmental process of black Muscovy breast muscles and will improve understanding of the underlying molecular mechanisms.