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.

Effects of duck circovirus on immune function and secondary infection of Avian Pathogenic Escherichia coli.

Duck circovirus (DuCV) infection occurs frequently in ducks in China and is generally believed to lead to immunosuppression and secondary infection, though there has been a lack of detailed research and direct evidence. In this study, one-day-old Cherry Valley ducklings were artificially infected with DuCV alone and co-infected with DuCV and Avian Pathogenic Escherichia coli (APEC). The immune indexes at 32 d old were systematically monitored, including immune organ weight, lymphocyte transformation rate, IL-10, IL-12, soluble CD4 (sCD4), soluble CD8 (sCD8), IFN-γ, viral loads in each organ, APEC colonization, and so on. The results showed the development of immune organs in ducklings was affected, resulting in a decrease in the lymphocyte transformation rate (LTR), IL-12, sCD4, sCD8, IFN-γ and an increase in IL-10 content at 8 to 32 d postinfection (dpi). In the detection of virus loads in some organs, it was found that 8 dpi, DuCV existed stably in various organs, suggesting the importance of preventing and controlling the virus in the early stage of culture. The results of exploring the DuCV infection that shows some influence on secondary infection by APEC. The results showed that DuCV infection could significantly enhance the pathogenicity of APEC and the colonization ability of APEC in vivo. DuCV can induce more serious APEC infection in 24 dpi than in 14 dpi. Based on the above results, it can be concluded that DuCV infection will affect the immune system, cause immunosuppression, and lead to more serious secondary infection.

Identification and antiviral effect of Cherry Valley duck IRF4.

Interferon regulatory factor 4 (IRF4) is a multifunctional transcription factor that plays an important regulatory role in the interferon (IFN) signaling. IRF4 participates in the process of antivirus, Th cell differentiation and B cell maturation by regulating the expression of IFN and some lymphokines. In this study, Cherry Valley duck IRF4 (duIRF4) was cloned and its cDNA was analyzed. Expression of duIRF4 in a wide variety of tissues and changes in duIRF4 expression due to viral infection also was detected by quantitative real-time PCR. The results show that duIRF4 contains 1,341 bp of ORF encoding a protein with 446 amino acids and contains 3 domains: DNA-binding domain (DBD), IRF-association domain (IAD) and nuclear localization signal (NLS). Quantitative real-time PCR analysis showed that duIRF4 was evenly expressed in all tissues examined, with the highest expression in the spleen, followed by the bursa of Fabricius, and lower in the skin and brain. In addition, expression of duIRF4 in the brain and spleen was significantly upregulated after being infected by duck plague virus, duck Tembusu virus, and novel duck reovirus. These data suggest that duIRF4 may be involved in innate immune response.

Tissue Specific Transcriptome Changes Upon Influenza A Virus Replication in the Duck.

Ducks are the natural host and reservoir of influenza A virus (IAV), and as such are permissive to viral replication while being unharmed by most strains. It is not known which mechanisms of viral control are globally regulated during infection, and which are specific to tissues during infection. Here we compare transcript expression from tissues from Pekin ducks infected with a recombinant H5N1 strain A/Vietnam 1203/04 (VN1203) or an H5N2 strain A/British Columbia 500/05 using RNA-sequencing analysis and aligning reads to the NCBI assembly ZJU1.0 of the domestic duck (Anas platyrhynchos) genome. Highly pathogenic VN1203 replicated in lungs and showed systemic dissemination, while BC500, like most low pathogenic strains, replicated in the intestines. VN1203 infection induced robust differential expression of genes all three days post infection, while BC500 induced the greatest number of differentially expressed genes on day 2 post infection. While there were many genes globally upregulated in response to either VN1203 or BC500, tissue specific gene expression differences were observed. Lungs of ducks infected with VN1203 and intestines of birds infected with BC500, tissues important in influenza replication, showed highest upregulation of pattern recognition receptors and interferon stimulated genes early in the response. These tissues also appear to have specific downregulation of inflammatory components, with downregulation of distinct sets of proinflammatory cytokines in lung, and downregulation of key components of leukocyte recruitment and complement pathways in intestine. Our results suggest that global and tissue specific regulation patterns help the duck control viral replication as well as limit some inflammatory responses in tissues involved in replication to avoid damage.

Duck Interleukin-22: Identification and Expression Analysis in Riemerella anatipestifer Infection.

Riemerella anatipestifer is one of the most devastating pathogens affecting the global duck farms. Infection is involved in secretion of proinflammatory cytokines, including interleukin- (IL-) 17A. During the immune response to infection, IL-22 and IL-17A are often produced concurrently and at high levels in inflamed tissues. Little is known about duck IL-22 (duIL-22) during R. anatipestifer infection. We describe the characterization of duIL-22 and its mRNA expression analysis in splenic lymphocytes and macrophages treated with heat-killed R. anatipestifer and in the spleens and livers of R. anatipestifer-infected ducks. Full-length cDNA of duIL-22 encoded 197 amino acids. The deduced amino acid sequence of duIL-22 shared a 30.4-40.5% similarity with piscine counterparts, 57.4-60.1% with mammalian homologs, and 93.4% similarity to the chicken. Duck IL-22 mRNA expression level was relatively high in the skin of normal ducks. It was increased in mitogen-stimulated splenic lymphocytes and in killed R. anatipestifer-activated splenic lymphocytes and macrophages. Compared with healthy ducks, IL-22 transcript expression was significantly upregulated in the livers and spleens on days 1 and 4 postinfection, but not on day 7. IL-17A was significantly increased in the spleens only on day 4 postinfection and in the livers at all time points. When splenic lymphocytes were stimulated with heat-killed R. anatipestifer, CD4+ cells predominantly produced IL-22 while IL-17A was expressed both by CD4+ and CD4- cells. These results suggested that IL-22 and IL-17A are likely expressed in different cell types during R. anatipestifer infection.

Characterization of duck IκB kinase ß involved in innate immunity.

IκB kinase ß (IKKß), a catalytic subunit of the IKK complex, is involved in a wide array of biological processes, particularly in inflammation and innate immunity. Although extensive studies have been carried out to explore the roles of mammalian IKKßs in innate immune response, the function of IKKß in avian innate immunity is largely unknown. Here, we cloned and characterized the duck IKKß (duIKKß) gene for the first time. DuIKKß encoded 755 amino acids and displayed high sequence similarity to pseudopodoces and haliaeetus IKKßs. DuIKKß transcripts were widely distributed in all tested tissues, especially with high expression in the thymus and bursa of Fabricius. Overexpression of duIKKß promoted NF-κB activation and initiated the downstream cytokines expression including IFN-ß, ZAP, PKR, IL-8, and CCL5 in duck embryo fibroblasts. Furthermore, knockdown of endogenous duIKKß significantly reduced LPS-, poly(I:C)- or SeV-induced NF-κB activation. Finally, we demonstrated that duIKKß showed antiviral activity against Duck Tembusu virus infection. Our findings provide insights into the roles of duIKKß in avian innate immunity.

Primary Chicken and Duck Endothelial Cells Display a Differential Response to Infection with Highly Pathogenic Avian Influenza Virus.

Highly pathogenic avian influenza viruses (HPAIVs) in gallinaceous poultry are associated with viral infection of the endothelium, the induction of a 'cytokine storm, and severe disease. In contrast, in Pekin ducks, HPAIVs are rarely endothelial tropic, and a cytokine storm is not observed. To date, understanding these species-dependent differences in pathogenesis has been hampered by the absence of a pure culture of duck and chicken endothelial cells. Here, we use our recently established in vitro cultures of duck and chicken aortic endothelial cells to investigate species-dependent differences in the response of endothelial cells to HPAIV H5N1 infection. We demonstrate that chicken and duck endothelial cells display a different transcriptional response to HPAI H5N1 infection in vitro-with chickens displaying a more pro-inflammatory response to infection. As similar observations were recorded following in vitro stimulation with the viral mimetic polyI:C, these findings were not specific to an HPAIV H5N1 infection. However, similar species-dependent differences in the transcriptional response to polyI:C were not observed in avian fibroblasts. Taken together, these data demonstrate that chicken and duck endothelial cells display a different response to HPAIV H5N1 infection, and this may help account for the species-dependent differences observed in inflammation in vivo.

Amelioration of Beta Interferon Inhibition by NS4B Contributes to Attenuating Tembusu Virus Virulence in Ducks.

Our previous studies reported that duck Tembusu virus nonstructural protein 2A (NS2A) is a major inhibitor of the IFNß signaling pathway through competitively binding to STING with TBK1, leading to a reduction in TBK1 phosphorylation. Duck TMUV NS2B3 could cleave and bind STING to subvert the IFNß signaling pathway. Here, we found that overexpression of duck TMUV NS4B could compete with TBK1 in binding to STING, reducing TBK1 phosphorylation and inhibiting the IFNß signaling pathway by using the Dual-Glo® Luciferase Assay System and the NanoBiT protein-protein interaction (PPI) assay. We further identified the E2, M3, G4, W5, K10 and D34 residues in NS4B that were important for its interaction with STING and its inhibition of IFNß induction, which were subsequently introduced into a duck TMUV replicon and an infectious cDNA clone. We found that the NS4B M3A mutant enhanced RNA replication and exhibited significantly higher titer levels than WT at 48-72 hpi but significantly decreased mortality (80%) in duck embryos compared to WT (100%); the NS4B G4A and R36A mutants slightly reduced RNA replication but exhibited the same titer levels as WT. However, the NS4B R36A mutant did not attenuate the virulence in duck embryos, whereas the G4A mutant significantly decreased the mortality (70%) of duck embryos. In addition, the NS4B W5A mutant did not affect viral replication, whereas the D34A mutant slightly reduced RNA replication, and both mutants exhibited significantly lower titer levels than the WT and significantly decreased mortality (90% and 70%, respectively) in duck embryos. Hence, our findings provide new insight into the development of attenuated flaviviruses by targeting the disabling viral strategies used to evade the innate defense mechanisms.

Molecular characterization and functional analysis of duck CCCH-type zinc finger antiviral protein (ZAP).

This is the first study to clone duck CCCH-type zinc finger antiviral protein (duZAP) from Jingjiang duck (Anas platyrhynchos). Full-length duZAP cDNA was 2154 bp and encoded a 717-amino acid polypeptide containing four highly conserved CCCH-type finger motifs, a WWE domain and a poly (ADP-ribose) polymerase (PARP) domain. duZAP was expressed in multiple duck tissues, with the highest mRNA expression in the spleen. Overexpression of duZAP in duck embryo fibroblast cells (DEFs) led to activation of the transcription factors IRF1 and NF-κB, and induction of IFN-ß. Analysis of deletion mutants revealed that both the WWE and PARP domains of duZAP were essential for activating the IFN-ß promoter. Knockdown of duZAP in DEFs significantly reduced poly (I:C)- and duck Tembusu virus (DTMUV)-induced IFN-ß activation. Our findings further the understanding of the role of duZAP in the duck innate immune response.

Influenza A Viruses in Whistling Ducks (Subfamily Dendrocygninae).

As compared to other Anseriformes, data related to influenza A virus (IAV) detection and isolation, and IAV antibody detection in whistling ducks (Dendrocygna spp. and Thalassornis leuconotus; subfamily Dendrocygninae) are limited. To better evaluate the potential role of whistling ducks in the epidemiology of IAV, we (1) conducted surveillance for IAV from black-bellied whistling ducks (BBWD, Dendrocygnaautumnalis) sampled in coastal Louisiana, USA, during February 2018 and 2019, and (2) reviewed the published literature and Influenza Resource Database (IRD) that reported results of IAV surveillance of whistling ducks. In the prospective study, from 166 BBWD sampled, one H10N7 IAV was isolated (0.6% prevalence), and overall blocking enzyme-linked immunosorbent assay (bELISA) antibody seroprevalence was 10%. The literature review included publications and data in the IRD from 1984 to 2020 that reported results from nearly 5000 collected samples. For any given collection, the IAV isolation rate never exceeded 5.5%, and seroprevalence estimates ranged from 0 to 42%. Results from our prospective study in Louisiana are consistent with this historic literature; however, although all data consistently demonstrated a low prevalence of infection, the potential role of this species in the epidemiology of IAV should not be totally discounted. In sum, whistling ducks can be infected with IAV, they represent important species on many areas where waterfowl winter, and their distribution across the globe appears to be changing.

Herd immunity drives the epidemic fadeout of avian cholera in Arctic-nesting seabirds.

Avian cholera, caused by the bacterium Pasteurella multocida, is a common and important infectious disease of wild birds in North America. Between 2005 and 2012, avian cholera caused annual mortality of widely varying magnitudes in Northern common eiders (Somateria mollissima borealis) breeding at the largest colony in the Canadian Arctic, Mitivik Island, Nunavut. Although herd immunity, in which a large proportion of the population acquires immunity to the disease, has been suggested to play a role in epidemic fadeout, immunological studies exploring this hypothesis have been missing. We investigated the role of three potential drivers of fadeout of avian cholera in eiders, including immunity, prevalence of infection, and colony size. Each potential driver was examined in relation to the annual real-time reproductive number (Rt) of P. multocida, previously calculated for eiders at Mitivik Island. Each year, colony size was estimated and eiders were closely monitored, and evaluated for infection and serological status. We demonstrate that acquired immunity approximated using antibody titers to P. multocida in both sexes was likely a key driver for the epidemic fadeout. This study exemplifies the importance of herd immunity in influencing the dynamics and fadeout of epidemics in a wildlife population.

Molecular characterization and functional analysis of duck IKKα.

IκB kinase α (IKKα) is a vital component of the IKK complex, which is involved in innate immune response, inflammation, cell death and proliferation. Although the functional characteristics of IKKα have been extensively studied in mammals and fish, the roles of IKKα in avian remain largely unknown. In this study, we cloned and characterized the duck IKKα (duIKKα) gene for the first time. DuIKKα encoded a protein of 757 amino acid residues and showed high sequence identities with the goose IKKα. The duIKKα was expressed in all tested tissues, and a relatively high expression of duIKKα mRNA was detected in liver and heart. Overexpression of duIKKα dramatically increased NF-κB activity and induced the expression of duck cytokines IFN-ß, IL-1ß, IL-6, IL-8 and RANTES in DEFs. Knockdown of duIKKα by small interfering RNA significantly decreased LPS-, poly(I:C)-, poly(dA:dT)-, duck enteritis virus (DEV)-, or duck Tembusu virus (DTMUV)-induced NF-κB activation. Moreover, duIKKα exhibited antiviral activity against DTMUV infection. These findings provide important insights into the roles of duIKKα in avian innate immunity.

Identification of a linear epitope within domain I of Duck Tembusu virus envelope protein using a novel neutralizing monoclonal antibody.

Duck Tembusu virus (DTMUV) is a newly emerging pathogenic flavivirus that caused severe egg drop syndrome in laying ducks in China since 2010, leading to massive economic losses to the duck industry. Although the DTMUV E protein is considered to be critical in inducing the protective immune response, the functional epitopes within this protein remain largely unknown. In the present study, we isolated a DTMUV neutralizing monoclonal antibody (mAb) 3B8 from DTMUV E-immunized mice. Epitope mapping showed that mAb 3B8 recognized a novel linear epitope FSCLGMQNR located on the extreme N-terminal of the domain I (EDI) of E protein. Sequence alignment and Western blot analyses showed that the epitope is greatly conserved with high DTMUV-specificity. Moreover, upon cloning the heavy and light chain variable region sequences of mAb 3B8, we prepared the single-chain variable antibody fragment (scFv) 3B8 by connecting the two chains via a flexible peptide linker. The recombinant scFv 3B8 exhibited antiviral activity against DTMUV infection in vitro and in vivo. Our results provide valuable implications for the development of DTMUV vaccines and therapeutics.

Duck HMGB2 Mediates Signaling Pathways in the Innate Immunity of Hosts Against Viral Infections.

High-mobility group box 2 (HMGB2) belongs to the HMG-box family that participates in a variety of biologic processes. Recent studies have suggested that HMGB2 plays an important role in the innate immunity of fish. Cherry Valley duck is the main duck bred for meat consumption in China, but there is limited research available on the impact of duck HMGB2 (duHMGB2) in antiviral innate immunity. Here, duHMGB2 genes were first cloned and analyzed from the spleen of Cherry Valley ducks. We show that duHMGB2 is widely distributed in most tissues of healthy ducks, and duHMGB2 was differentially expressed in three organs (the spleen, brain, and lung) of ducks during different viral infections. duHMGB2 is mainly expressed in the nucleus of duck embryo fibroblast (DEF) cells. However, duHMGB2 is released into the cytoplasm after viral infection. DuHMGB2 induced expression of several genes that regulate the immune response. Moreover, duHMGB2 activated and upregulatede transcription factor NF-κB promoter activity. We also used single gene manipulations (knockout or overexpression) to confirm that duHMGB2 can inhibit the replication of duck plague virus, duck Tembusu virus, and the novel duck reovirus in DEF cells. These data show that duHMGB2 can activate the antiviral innate immunity of the host. Thus, duHMGB2 may be considered an immune adjuvant against infectious diseases in duck.

Interleukin-2 shows high adjuvanticity for an inactivated vaccine against duck Tembusu virus disease.

Currently, the widely used vaccine against duck Tembusu virus (DTMUV) disease is inactivated vaccine which, however, facing the limits of large inoculation dose, short immunization period, and incomplete effectiveness. Access to efficient adjuvants aiding for DTMUV inactivated vaccine seems to be of critical importance. Interleukin-2 (IL-2) was reported to induce a persistent expansion of effector T cells and could be a promising molecular adjuvant for many kinds of vaccines. In this study, the efficacy of duck interleukin (dIL)-2 as an adjuvant for a DTMUV inactivated vaccine was evaluated. Fifty-five Pekin ducks were divided into 5 groups and intramuscularly administered with 5 batches of vaccines at 42 D (A: DTUMV + dIL-2; B: 1/2DTUMV + dIL-2; C: DTUMV; D: 1/2DTUMV and E: PBS), respectively, and received the second vaccination 2 wk later. Fifty-six days after immunization, 6 ducks from each group were randomly selected to conduct a challenge protection test. Antibody titers and cytokine responses were detected to assess humoral and cellular immune responses in serum of inoculated ducks by hemagglutination inhibition and ELISA, respectively; virus isolation and RT-PCR method were used in immunity protective test. Our results showed that dIL-2 exerted an enhanced effect on the vaccine while reducing the dose of inoculated antigen highlighting high adjuvanticity of IL-2. The vaccines supplemented with IL-2 induced a higher level of antibodies and higher percentage of inhibition values than inactivated vaccines without IL-2 to a significant extent. The production level of IFN-α, IFN-γ, and IL-6 genes were elevated, enhancing both humoral and cellular responses. Furthermore, it provided higher protection after virus challenge. Therefore, IL-2 can be considered as a potential adjuvant for inactivated vaccine against DTMUV disease.

Effects of glucose oxidase on growth performance, immune function, and intestinal barrier of ducks infected with Escherichia coli O88.

The negative effects of dietary antibiotics have become a widespread concern. It is imperative to search for a new type of green, safe, and efficient feed additive that can replace antibiotics. This study was to investigate the effects of glucose oxidase (GOD) on growth performance, immune function, and intestinal barrier in ducks infected with Escherichia coli O88. First, we established the E. coli challenge model of ducks through a preliminary experiment and then carried out the formal experiment by using 144 1-day-old male lean Peking ducklings (50 ± 2.75 g). All ducks were randomly assigned to 1 of 3 dietary treatment groups of basal diet (control), 30 mg/kg virginiamycin (antibiotic), and 200 U/kg GOD (1,000 U/g). Each group consisted of 6 replications with 8 birds per replicate. At day 7, all ducks were orally administered 0.2 mL E coli O88 (3 × 109 cfu/mL) twice, 8 h apart based on the preliminary experiment. The experiment lasted for 28 d. Dietary supplementation with GOD improved growth performance of ducks infected with E. coli. The GOD increased contents of Ig in plasma and secreted Ig A in jejunal mucosa. The GOD group had lower concentrations of inflammatory cytokines (tumor necrosis factor-α, IL-1ß, and IL-6) and their upstream regulator Toll-like receptor 4 in the jejunum of ducks than the control group. Supplementation with GOD increased villus height and decreased crypt depth in the jejunum. The gene expression of tight junction proteins (zonula occludens-1, claudin-1 and claudin-2) was enhanced by adding GOD. The GOD decreased intestinal permeability by reducing the concentrations of diamine oxidase and D-lactic in plasma of ducks. There were no significant differences in almost all the indices tested between the GOD and the antibiotic groups. In conclusion, supplementation of GOD improved growth performance, immune function, and intestinal barrier of ducks infected with E. coli O88. Glucose oxidase may serve as a promising alternative therapy to antibiotics to relieve or prevent colibacillosis in ducks.

Effects of Achyranthes bidentata polysaccharides on performance, immunity, antioxidant capacity, and meat quality in Pekin ducks.

This study was conducted to evaluate the effects of Achyranthes bidentata polysaccharide (ABP) on growth performance, antioxidant capacity, immune function, relative organ weight, ileal microflora, and meat quality in Pekin ducks. A total of 1,200 female 1-day-old Pekin ducklings (51.2 ± 0.2 g) were blocked based on body weight (BW) and randomly allocated into 3 treatments with 10 replicates of 40 birds each. The experiment lasted for 6 wk, and dietary treatments included corn-soybean meal-based diet supplemented with 0, 0.02, and 0.04% ABP. The supplementation of ABP increased (P < 0.05) body weight gain (BWG) and final BW linearly during day 22 to 42 and day 1 to 42, respectively, but decreased (P < 0.05) feed-to-gain ratio (F/G) linearly during day 22 to 42 and day 1 to 42. The inclusion of ABP increased (P < 0.05) serum superoxide dismutase, glutathione peroxidase, total antioxidative capacity, catalase, complement3, complement4, immunoglobin A, immunoglobin G, interleukin-2, interferon-γ, and tumor necrosis factor-α linearly. The relative weight of breast meat was increased (P < 0.05) linearly, but the relative weight of abdominal fat was decreased (P < 0.05) linearly with the increasing dietary ABP supplementation. The supplementation of ABP increased (P < 0.05) ileal Lactobacilli counts linearly, whereas decreased (P < 0.05) Escherichia coli counts linearly. Taken together, the inclusion of ABP promoted BWG and final BW during day 22 to 42 and the entire experiment, decreased F/G during day 22 to 42 and day 1 to 42, and partially improved antioxidant activities, immunity, and gut microflora in Pekin ducks.

Differences in the growth rate and immune strategies of farmed and wild mallard populations.

Individuals reared in captivity are exposed to distinct selection pressures and evolutionary processes causing genetic and phenotypic divergence from wild populations. Consequently, restocking with farmed individuals may represent a considerable risk for the fitness of free-living populations. Supportive breeding on a massive scale has been established in many European countries to increase hunting opportunities for the most common duck species, the mallard (Anas platyrhynchos). It has previously been shown that mallards from breeding facilities differ genetically from wild populations and there is some indication of morphological differences. Using a common-garden experiment, we tested for differences in growth parameters between free-living populations and individuals from breeding facilities during the first 20 days of post-hatching development, a critical phase for survival in free-living populations. In addition, we compared their immune function by assessing two haematological parameters, H/L ratio and immature erythrocyte frequency, and plasma complement activity. Our data show that farmed ducklings exhibit larger morphological parameters, a higher growth rates, and higher complement activity. In haematological parameters, we observed high dynamic changes in duckling ontogeny in relation to their morphological parameters. In conclusion, our data demonstrate pronounced phenotype divergence between farmed and wild mallard populations that can be genetically determined. We argue that this divergence can directly or indirectly affect fitness of farmed individuals introduced to the breeding population as well as fitness of farmed x wild hybrids.

Effects of pantothenic acid on growth performance and antioxidant status of growing male white Pekin ducks.

An experiment was conducted to investigate the effects of dietary pantothenic acid levels on growth performance, carcass traits, pantothenic acid status, and antioxidant status of male white Pekin ducks from 15 to 42 D of age and to evaluate the requirement of this vitamin for growing ducks. Different levels pantothenic acid (0, 2, 4, 6, 8, and 10 mg/kg) were supplemented to a corn-soy isolate protein basal diet to produce 6 dietary treatments with different analyzed total pantothenic acid levels (4.52, 6.44, 8.37, 9.88, 12.32, and 14.61 mg/kg). A total of 240 15-day-old male white Pekin ducks were allotted to 6 dietary treatments with 8 replicate pens of 5 birds per pen. At 42 D of age, growth performance, carcass traits, tissue pantothenic acid concentrations, and antioxidant status of white Pekin ducks were examined. Significant effects of dietary pantothenic acid on BW, average daily weight gain (ADG), plasma, and liver pantothenic acid concentrations were observed (P < 0.05) but not carcass traits. The growing ducks fed the basal diet without pantothenic acid supplementation had the lowest BW, ADG, plasma, and liver pantothenic acid content among all ducks (P < 0.05). In addition, the ducks fed the basal diet without pantothenic acid supplementation showed the lowest antioxidant capacity indicated by greatest plasma malondialdehyde content and lowest liver total antioxidant capacity (P < 0.05). And, these criteria responded linearly as dietary pantothenic acid levels increased (P < 0.05). These results indicated that dietary pantothenic acid supplementation improved growth performance and antioxidant status of the growing ducks. In accordance with the broken-line model, the pantothenic acid requirements (based on dietary total pantothenic acid) of male white Pekin ducks from 15 to 42 D of age for BW, ADG, and plasma and liver pantothenic acid contents were 10.18, 10.27, 12.06, and 10.79 mg/kg, respectively.

Differently Expression Analysis and Function Prediction of Long Non-coding RNAs in Duck Embryo Fibroblast Cells Infected by Duck Tembusu Virus.

Duck Tembusu virus (DTMUV), the causative agent of egg-drop syndrome, has caused substantial economic losses to duck industry. DTMUV infection leads to profound changes of host cells, including transcriptome and proteome. However, the lncRNA expression profile and the biological function of lncRNA have not been revealed. Therefore, DTMUV was used to inoculate duck embryo fibroblast cells (DEFs) for high-throughput RNA-sequencing (RNA-Seq). The results showed that 34 and 339 differently expressed lncRNAs were, respectively, identified at 12 and 24 h post-infection (hpi). To analyze their biological functions, target genes in cis were searched and the regulatory network was formed. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that the target genes were strongly associated with immune system, signaling molecular and interaction, endocrine system, and signal transduction. The differently expressed lncRNAs were selected and verified by quantitative real-time polymerase chain reaction (RT-qPCR). Our study, for the first time, analyzed a comprehensive lncRNA expression profile in DEFs following DTMUV infection. The analysis provided a view on the important roles of lncRNAs in gene regulation and DTMUV infection.