Zinc glycine chelate ameliorates DSS‑induced intestinal barrier dysfunction via attenuating TLR4/NF‑κB pathway in meat ducks

Background Zinc glycine chelate(Zn-Gly)has anti-inflammation and growth-promoting properties;however,the mechanism of Zn-Gly contribution to gut barrier function in Cherry Valley ducks during intestinal inflammation is unknown.Three-hundred 1-day-old ducks were divided into 5 groups(6 replicates and 10 ducks per replicate)in a completely randomized design:the control and dextran sulfate sodium(DSS)groups were fed a corn-soybean meal basal diet,and experimental groups received supplements of 70,120 or 170 mg/kg Zn in form of Zn-Gly.The DSS and treatment groups were given 2 mL of 0.45 g/mL DSS daily during d 15–21,and the control group received normal saline.The experiment lasted 21 d.Results Compared with DSS group,70,120 and 170 mg/kg Zn significantly increased body weight(BW),villus height and the ratio of villus to crypt,and significantly decreased the crypt depth of jejunum at 21 d.The number of goblet cells in jejunal villi in the Zn-Gly group was significantly increased by periodic acid-Schiff staining.Compared with control,the content of intestinal permeability marker D-lactic acid(D-LA)and fluxes of fluorescein isothiocyanate(FITC-D)in plasma of DSS group significantly increased,and 170 mg/kg Zn supplementation significantly decreased the D-LA content and FITC-D fluxes.Compared with control,contents of plasma,jejunum endotoxin and jejunum pro-inflammatory factors IL-1β,IL-6 and TNF-αwere significantly increased in DSS group,and were significantly decreased by 170 mg/kg Zn supplementation.Dietary Zn significantly increased the contents of anti-inflammatory factors IL-10,IL-22 and sIgA and IgG in jejunum.Real-time PCR and Western blot results showed that 170 mg/kg Zn supplementation significantly increased mRNA expression levels of CLDN-1 and expression of OCLN protein in jejunum,and decreased gene and protein expression of CLDN-2 compared with DSS group.The 120 mg/kg Zn significantly promoted the expressions of IL-22 and IgA.Dietary Zn-Gly supplementation significantly decreased pro-inflammatory genes IL-8 and TNF-αexpression levels and TNF-αprotein expression in jejunum.Additionally,Zn significantly reduced the gene and protein expression of TLR4,MYD88 and NF-κB p65.Conclusions Zn-Gly improved duck BW and alleviated intestinal injury by regulating intestinal morphology,barrier function and gut inflammation-related signal pathways TLR4/MYD88/NF-κB p65.

River width and depth as key factors of diurnal activity energy expenditure allocation for wintering Spot-billed Ducks in the Xin'an River Basin

Rivers are important habitats for wintering waterbirds.However,they are easily influenced by natural and human activities.An important approach for waterbirds to adapt to habitats is adjusting the activity time and energy expenditure allocation of diurnal behavior.The compensatory foraging hypothesis predicts that increased energy expenditure leads to longer foraging time,which in turn increases food intake and helps maintain a constant energy balance.However,it is unclear whether human-disturbed habitats result in increased energy expenditure related to safety or foraging.In this study,the scan sample method was used to observe the diurnal behavior of the wintering Spot-billed Duck(Anas poecilorhyncha) in two rivers in the Xin’an River Basin from October 2021 to March 2022.The allocation of time and energy expenditure for activity in both normal and disturbed environments was calculated.The results showed that foraging accounted for the highest percentage of time and energy expenditure.Additionally,foraging decreased in the disturbed environment than that in the normal environment.Resting behavior showed the opposite trend,while other behaviors were similar in both environments.The total diurnal energy expenditure of ducks in the disturbed environment was greater than that in the normal environment,with decreased foraging and resting time percentage and increased behaviors related to immediate safety(swimming and alert) and comfort.These results oppose the compensatory foraging hypothesis in favor of increased security.The optimal diurnal energy expenditure model included river width and water depth,which had a positive relationship;an increase in either of these two factors resulted in an increase in energy expenditure.This study provides a better understanding of energy allocation strategies underlying the superficial time allocation of wintering waterbirds according to environmental conditions.Exploring these changes can help understand the maximum fitness of wintering waterbirds in response to nature and human influences.

Mobile genetic elements facilitate the transmission of antibiotic resistance genes in multidrug-resistant Enterobacteriaceae from duck farms

Multidrug-resistant(MDR)Enterobacteriaceae critically threaten duck farming and public health.The phenotypes,genotypes,and associated mobile genetic elements(MGEs)of MDR Enterobacteriaceae isolated from 6 duck farms in Zhejiang Province,China,were investigated.A total of 215 isolates were identified as Escherichia coli(64.65%),Klebsiella pneumoniae(12.09%),Proteus mirabilis(10.23%),Salmonella(8.84%),and Enterobacter cloacae(4.19%).Meanwhile,all isolates were resistant to at least two antibiotics.Most isolates carried tet(A)(85.12%),blaTEM(78.60%)and sul1(67.44%)resistance genes.Gene co-occurrence analysis showed that the resistance genes were associated with IS26 and integrons.A conjugative IncFII plasmid pSDM004 containing all the above MGEs was detected in Proteus mirabilis isolate SDM004.This isolate was resistant to 18 antibiotics and carried the blaNDM-5 gene.MGEs,especially plasmids,are the primary antibiotic resistance gene transmission route in duck farms.These findings provide a theoretical basis for the rational use of antibiotics in farms which are substantial for evaluating public health and food safety.

Transcriptome analysis reveals the genetic basis of crest cushion formation in duck

The Chinese crested duck is a unique duck breed having a bulbous feather shape on its duck head.However,the mechanisms involved in its formation and development are unclear.In the present study,RNA sequencing analysis was performed on the crested tissues of 6 Chinese crested ducks and the scalp tissues of 6 cherry valley ducks(CVs)from 2 developmental stages.This study identified 261 differentially expressed genes(DEGs),122 upregulated and 139 downregulated,in the E28 stage and 361 DEGs,154 upregulated and 207 downregulated in the D42 stage between CC and CV ducks.The subsequent results of weighted gene co-expression network analysis(WGCNA)revealed that the turquoise and cyan modules were associated with the crest trait in the D42 stage,meanwhile,the green,brown,and pink modules were associated with the crest trait in the E28 stage.Venn analysis of the DEGs and WGCNA showed that 145 and 45 genes are associated between the D42 and E28 stages,respectively.The expression of WNT16,BMP2,SLC35F2,SLC6A15,APOBEC2,ABHD6,TNNC2,MYL1,and TNNI2 were verified by real-time quantitative PCR.This study provides an approach to reveal the molecular mechanisms underlying the crested trait development.

Effects of Probiotics on Growth Performance and Blood Biochemical Indexes of Cherry Valley Ducks

In order to investigate the effects of probiotics on growth performance, blood biochemical indexes and economic benefits of Cherry Valley ducks, different probiotics were added into the feed of Cherry Valley ducks. Total 240 1-d-old Cherry Valley ducks were selected, and they were randomly divided into 4 groups, including 1 control group and 3 treatment groups. There were 3 replicates for each group and there were 20 ducks for each replicate. The ducks in the control group were fed the basal diet, and the ducks in the 3 treatment groups were fed the basal diet added with Lactobacillus, Bacillus natto and florfenicol, respectively. The test lasted for 42 d. The results showed that the addition of Lactobacillus and Bacillus natto could improve the average daily weight gain and final average weight （P〈0.05） of Cherry Valley ducks, and reduce the glutamic-pyruvic transaminase ac- tivity, alkaline phosphatase activity and serum urinary nitrogen content in duck blood （P〈0.05） and reduce the creatinine content and total cholesterol content in Cherry Valley ducks （P〉0.05）; at the same time, adding probiotics to feed could also in- crease the grass economic benefits of Cherry Valley ducks. In overall, the effects of adding probiotics were better than those of adding antibiotic.

右半结肠癌中p53,ki-67的表达及与分化程度及Ducks分期的关系

目的:研究p53,ki-67在右半结肠癌组织中的表达,初步探讨两者与结肠癌分化程度和Ducks分期的关系方法:统计89例右半结肠癌病人肿瘤p53,ki-67的表达,结合临床病理进行分析。结果:右半结肠癌p53蛋白阳性表达与结肠癌分化程度和Ducks分期有关,ki-67蛋白的表达强度与Ducks分期有关。结论:检测p53、ki-67的表达对临床治疗及预后有一定的指导意义。

Ducks’B期直肠癌淋巴结中的GCCmRNA表达与预后的关系

目的探讨GCCm RNA在Ducks’B期直肠癌淋巴结中表达与预后的关系及能否作为判定淋巴隐匿性转移的有效指标。方法应用RT-PCR检测33例Ducks’B期直肠癌淋巴结中GCCm RNA表达水平,并分析患者的局部复发率、3年无瘤生存率(PFS)、3年总生存率(OS)与不同GCCm RNA表达水平的关系。结果 GCCm RNA阴性组患者的局部复发率和远处转移率更低(P<0.01),无瘤生存率与总生存率更高(P<0.01)。结论 GCCm RNA不同表达状态Ducks’B期直肠癌患者的预后有差异,GCCm RNA可以作为直肠癌淋巴结微转移的有效检测指标,可以作为甄别p N0直肠癌高危患者的可靠分子学指标,有利于高危患者后续辅助治疗的选择。

Nutritional requirements of meat-type and egg-type ducks: what do we know?

The demand for duck meat, duck eggs, and associated products is increasing each year. Classic and modern selection programs have been applied to enhance the economic traits of ducks to satisfy the requirements of consumers and enhance the incomes of producers. The nutritional requirements of unselected ducks may not be adequate, however, to fulfill the potential productivity performance of modern birds, including both meat-type and egg-type ducks. In particular, an imbalanced diet is associated with low productive performance and signs of nutritional deficiency（if insufficient nutrients are supplied）, as well as with high feed costs and manure problems that reflect flock health and welfare（if excessive nutrients are supplied）. Thus, the main aim of this review is to summarize the results of previous studies that estimated the nutrient requirements of meat-type and egg-type ducks in order to evaluate current knowledge and to identify further issues that need to be addressed. In addition,the results obtained in previous studies are compared in order to understand how to lower commercial feed costs,fulfill the genetic potential of selected ducks, protect the environment from pollution, and satisfy the welfare and health needs of ducks.

Tracking domestic ducks:A novel approach for documenting poultry market chains in the context of avian influenza transmission

Agro-ecological conditions associated with the spread and persistence of highly pathogenic avian inlfuenza （HPAI） are not well understood, but the trade of live poultry is suspected to be a major pathway. Although market chains of live bird trade have been studied through indirect means including interviews and questionnaires, direct methods have not been used to identify movements of individual poultry. To bridge the knowledge gap on quantitative movement and transportation of poultry, we introduced a novel approach for applying telemetry to document domestic duck movements from source farms at Poyang Lake, China. We deployed recently developed transmitters that record Global Positioning System （GPS） locations and send them through the Groupe Spécial Mobile （GSM） cellular telephone system. For the ifrst time, we were able to track individually marked ducks from 3 to 396 km from their origin to other farms, distribution facilities, or live bird markets. Our proof of concept test showed that the use of GPS-GSM transmitters may provide di-rect, quantitative information to document the movement of poultry and reveal their market chains. Our ifndings provide an initial indication of the complexity of source-market network connectivity and highlight the great potential for future telemetry studies in poultry network analyses.

Identification of Novel and Differentially Expressed MicroRNAs in the Ovaries of Laying and Non-Laying Ducks

MicroRNAs （miRNAs）, which post-transcriptionally regulate gene expression by binding to the 3′untranslated region of mRNAs to either inhibit or enhance translation, are involved in diverse biological processes. The use of high-throughput Solexa sequencing plays important roles in the discovery of miRNAs. In this study, we used high-throughput Solexa sequencing to identify novel duck miRNAs and compare the miRNA expression profiles in laying and non-laying duck ovaries. Using a bioinformatic analysis, we discovered 86 potential duck miRNAs similar to known chicken miRNAs and 43 unique sequences that matched known miRNAs of other species. We also found that miRNA variations and isoforms were widespread in our two RNA libraries, with most of the variations occurring in the 3′region of the miRNAs. Furthermore, we detected 55 miRNAs that exhibited significant expression differences between laying and non-laying ducks. Gene ontology （GO） and kyoto encyclopedia of genes and genomes （KEGG） enrichment analyses of the potential targets of the differentially expressed miRNAs indicated these miRNAs may play key roles in the egg laying process. Finally, we confirmed the differential expression of 5 miRNAs in the laying and non-laying samples by qRT-PCR. Cumulatively, our work provides the first look at the miRNA expression profile of the duck ovary and provides novel insight into the roles of miRNAs in egg laying and reproduction.

IFN-γ increases efficiency of DNA vaccine in protecting ducks against infection

AIM： To detect the effects of DNA vaccines in combination with duck IFN-γ gene on the protection of ducks against duck hepatitis B virus （DHBV） infection. METHODS： DuIFN-γ cDNA was cloned and expressed in COS-γ cells, and the antiviral activity of DuIFN-γ was detected and neutralized by specific antibodies, Ducks were vaccinated with DHBpreS/S DNA alone or coimmunized with plasmid expressing DuIFN-γ. DuIFN-γ mRNA in peripheral blood mononuclear cells （PBMCs） from immunized ducks was detected by semi-quantitative competitive RT-PCR. Anti-DHBpreS was titrated by enzyme-linked immunosorbent assay （EUSA）. DHBV DNA in sera and liver was detected by Southern blot hybridization, after ducks were challenged with high doses of DHBV. RESULTS： DuIFN-γ expressed by COS-γ was able to protect duck fibroblasts against vesicular stomatitis virus （VSV） infection in a dose-dependent fashion, and anti DuIFN-γ antibodies neutralized the antiviral effects. DuIFN-γ in the supernatant also inhibited the release of DHBV DNA from LMH-D2 cells. When ducks were co-immunized with DNA vaccine expressing DHBpreS/S and DuIFN-γ gene as an adjuvant, the level of DuIFN-γ mRNA in PBMCs was higher than that in ducks vaccinated with DHBpreS/S DNA alone. However, the titer of anti-DHBpreS elicited by DHBpreS/S DNA alone was higher than that co-immunized with DuIFN-γ gene and DHBpreS/S DNA. After being challenged with DHBV at high doses, the load of DHBV in sera dropped faster, and the amount of total DNA and cccDNA in the liver decreased more significantly in the group of ducks co-immunized with DuIFN-γ gene and DHBpreS/S DNA than in other groups.

PCR Detection and Sequence Analysis of Duck Circovirus in Sick Muscovy Ducks

The duck circovirus （DuCV） infection in sick ducks from Fujian Province was investigated. The liver samples of 43 sick Muscovy ducks with infectious serositis were collected from 12 duck farms in Fujian Province Based on the published sequences of DuCV, two primers were designed for the detection of DuCV and four pairs of primers were designed to amplify four overlapping fragments that cover the complete genome of DuCV. The specific PCR products were amplified from positive samples. The fragments were then cloned into pMD18-T vector and sequenced, and the full length genomic sequence of the FJ0601 isolate of DuCV was obtained. PCR analysis showed that the proportion of ducks which were positive for circovirus was 79% and 10 out of the 12 farms were positive. Sequence analysis showed that the complete genome of DuCV-FJ0601 was 1988 bp and possessed features common to the family Circoviridae which included a stem-loop structure and the Rep protein motifs. Homology analysis showed that FJ0601 isolate of DuCV had 97.3%-97.5% nucleotide sequence identity to all the four Taiwan isolates （TC1/2002, TC2/2002, TC3/2002, TC4/2002）, 82.9% identity to the America （33753-52） isolate and 82.3% identity to the Germany isolate. Phylogenetic analysis with Clustal W, however, showed that FJ0601 isolate of DuCV was on a common branch with Taiwan isolates, and Germany and America isolates belonged to the other branch.

Artificial Insemination of Cherry Valley Ducks with Muscovy Ducks

[Objective] To explore artificial insemination technique for production of mule ducks. [Method] Female Cherry Valley ducks were artificially inseminated with semen collected from male Muscovy ducks by massage method and vagina-insemination method to investigate the effects of insemination dose, insemination interval, insemination time and diluents on fertilization rate. [ Result ] The average fertilization rate was only 39.58%, when the female Cherry Valley ducks naturally mated with the male Muscovy ducks. However, it was increased to 74.79% by artificial insemination. The fertilization rate was 75.24% after semen was diluted by PBS buffer, while it was 75.16% after semen was diluted by Lake＇s buffer; however, there was not significant difference between the fertilization rate of the diluted semen and that of fresh semen （74.10%）. After semen was respectively diluted by PBS buffer and Lake＇s buffer and then stored at 5 ℃ for 24 h, the fertilization rate was low, respectively 23.76% and 34133%. [ Conclusion] Artificial insemination technology can reduce insemination dose and increase fertilization rate in production of mule ducks.

Immunogenicity and protective efficacy of DHBV DNA vaccines expressing envelope and capsid fusion proteins in ducks delivered by attenuated Salmonella typhimurium

Duck hepatitis B virus(DHBV) shares many basic characteristics with hepatitis B virus(HBV) and is an attractive model for vaccine development. In this study, DHBV DNA vaccines were designed to express envelope and capsid fusion proteins to enhance the breadth of immune response in ducks. Attenuated Salmonella typhimurium(SL7207) was used as a carrier and adjuvant to boost the magnitude of immune response. Based on this strategy, novel DNA vaccines(SL7207-p VAX1-LC and SL7207-p VAX1-SC) were generated. Growth kinetics, genetic stabilities and relative transcription levels of the L, S and C genes introduced by these vaccine strains were measured before inoculation to guarantee safety and efficacy. The relative transcript levels of the CD4 and CD8 T genes and the antibody levels(Ig Y) in ducks receiving the vaccines were higher than those in single gene delivered groups. Additionally, the copy number of covalently closed circular DNA in hepatocytes after DHBV challenge also provided evidence that our fusion vaccines could enhance the protective efficiency against DHBV infection in ducks.

Systematic analysis of feeding behaviors and their effects on feed efficiency in Pekin ducks

Background： Feeding behavior study is important for animal husbandry and production. However, few studies were conducted on the feeding behavior and their relationship with feeding efficiency in Pekin ducks. In order to investigate the feeding behavior and their relationship with feed efficiency and other economic traits in Pekin ducks, we selected 358 male Pekin ducks and recorded feeding information between 3 to 6 wk of age using automatic electronic feeders, and compared the feeding behavior under different residual feed intake（RFI） levels.Results： We observed that total feed time, daily feed intake and feed intake per meal had strong positive correlations with feed efficiency traits; moreover, strong correlation between feed intake per meal and body weight was found（R=0.32, 0.36）. Daily feeding rate meal and meal duration had weak correlations with feed efficiency（R=0.14~0.15）. The phenotypic correlation of between-meal pauses, with feed efficiency was not observed. When daily changes were analyzed, high RFI ducks had the highest feed consumption over all times, and obvious differences in daily visits were found among different RFI level animals during the middle period; these differences were magnified with age, but there was no difference in daily meal number. Moreover, our data indicate that high RFI birds mainly take their meals at the edge of the population enclosure, where they are more susceptible to environmental interference.Conclusions： Overal, this study suggests that the general feeding behaviors can be accurately measured using automatic electronic feeders and certain feeding behaviors in Pekin ducks are associated with improved feed efficiency.

A New Detecting Method for the Sequence Difference of CHD1 Gene on Sex Chromosomes Z and W in Domesticated Ducks of China

A new method for detecting the sequence differences of duck Chromo-helicase-DNA-Binding 1 （ CHD1 ） genes on sex chromosomes Z and W was established by amplifying DNA fragment length poly morphism, which aimed to solve some technical problems, such as the sex identification with nondamage, the misclassifc rate of artificial sex identification during embryonic period, and the injury caused by anal reversal identification method during neonatal period. The im- proved sex identification method was developed by DNA amplified fragment length polymorphism by using CHD1 gene sequence in bird. The sex identification PCR primers YPF/YPR were used, and the PCR product was cloned, sequenced and blasted; and the effectiveness and accuracy of this method were verified through liv- ing examples. 2% agarose gel electrophoresis was used to distinguish 495 bp CHD1-Z and 351 bp CHD1-W obtained by primer YPF/YPR. The female （ZW） dis- played two visible bands; while male （ZZ） had only one single band. It was proved that this method for detecting the sequence differences of duck CHD1 gene was visual and reliable, and the molecular marker provided was effective and precise in the sex molecular biological identification of domesticated duck in China.

Protective efficacy of an H5/H7 trivalent inactivated vaccine(H5-Re13,H5-Re14, and H7-Re4 strains) in chickens, ducks, and geese against newly detected H5N1, H5N6, H5N8, and H7N9 viruses

Some H5 viruses isolated in poultry or wild birds between 2020 and 2021 were found to be antigenically different from the vaccine strains(H5-Re11 and H5-Re12) used in China. In this study, we generated three new recombinant vaccine seed viruses by using reverse genetics and used them for vaccine production. The vaccine strain H5-Re13 contains the hemagglutinin(HA) and neuraminidase(NA) genes of an H5 N6 virus that bears the clade 2.3.4.4 h HA gene, H5-Re14 contains the HA and NA genes of an H5 N8 virus that bears the clade 2.3.4.4 b HA gene, and H7-Re4 contains the HA and NA genes of H7 N9 virus detected in 2021. We evaluated the protective efficacy of the novel H5/H7 trivalent inactivated vaccine in chickens, ducks, and geese. The inactivated vaccine was immunogenic and induced substantial antibody responses in the birds tested. Three weeks after vaccination, chickens were challenged with five different viruses detected in 2020 and 2021: three viruses(an H5 N1 virus, an H5 N6 virus, and an H5 N8 virus) bearing the clade 2.3.4.4 b HA gene, an H5 N6 virus bearing the clade 2.3.4.4 h HA gene, and an H7 N9 virus. All of the control birds shed high titers of virus and died within 4 days post-challenge, whereas the vaccinated chickens were completely protected from these viruses. Similar protective efficacy against H5 viruses bearing the clade 2.3.4.4 h or 2.3.4.4 b HA gene was observed in ducks and geese. Our study indicates that the newly updated H5/H7 vaccine can provide solid protection against the H5 and H7 N9 viruses that are currently circulating in nature.

Dietary threonine deficiency affects expression of genes involved in lipid metabolism in adipose tissues of Pekin ducks in a genotype-dependent manner

Dietary threonine(Thr) deficiency increases hepatic triglyceride content and reduces sebum and abdominal fat percentages in lean type(LT), but not in fatty type(FT) Pekin ducks. However, the molecular changes regarding the role of Thr in lipid metabolism in LT and FT ducks induced by Thr deficiency remains unknown. This study compared differential expression gene profiles related to lipid metabolism in FT and LT Pekin ducks affected by Thr deficiency. We performed transcriptomic profiling and scanned the gene expression in the liver, sebum, and abdominal fat of Pekin ducks fed either Thr-deficient or Thr-adequate diet for 21 days from 14 to 35 days of age. There were 187, 52, and 50 differentially expressed genes(DEGs) identified in the liver, sebum, and abdominal fat of LT ducks affected by Thr deficiency, of which 12, 9, and 5 genes were involved in lipid metabolism, respectively. Thr deficiency altered the expression of 27, 6, and 3 genes in FT ducks’ liver, sebum, and abdominal fat, respectively. None of the DEGs had a relationship with lipid metabolism in FT ducks. KEGG analysis showed that the DEGs in the LT ducks’ livers were enriched in lipid metabolism pathways(linolenic acid metabolism, glycerophospholipid metabolism, and arachidonic acid metabolism) and amino acid metabolism pathways(biosynthesis of amino acids, phenylalanine metabolism, β-alanine metabolism, and glycine, serine and threonine metabolisms). The DEGs in the sebum and abdominal fat of LT ducks were not enriched in lipid and amino acid metabolic pathways. Additionally, DEGs involved in lipid metabolism were found to be upregulated by Thr deficiency in LT ducks, such as malic enzyme 3(ME3), acyl-Co A synthetase short-chain family member 2(ACSS2) in liver, and lipase member M(LIPM) in sebum. In summary, dietary Thr deficiency regulated the gene expression involved in lipid metabolism in the liver, sebum, and abdominal fat of Pekin ducks in a genotype-dependent manner.

Dietary methionine deficiency stunts growth and increases fat deposition via suppression of fatty acids transportation and hepatic catabolism in Pekin ducks

Background:Although methionine(Met),the first-limiting dietary amino acid,has crucial roles in growth and regulation of lipid metabolism in ducks,mechanisms underlying are not well understood.Therefore,the objective was to use dietary Met deficiency to investigate the involvement of Met in lipid metabolism and fat accumulation of Pekin ducks.Methods:A total of 150 male Pekin ducks(15-d-old,558.5±4.4 g)were allocated into 5 groups(6 replicates with 5 birds each)and fed corn and soybean meal-based diets containing 0.28%,0.35%,0.43%,0.50%,and 0.58%Met,respectively,for 4 weeks.Met-deficient(Met-D,0.28%Met)and Met-adequate(Met-A,0.43%Met)groups were selected for subsequent molecular studies.Serum,liver,and abdominal fat samples were collected to assess the genes and proteins involved in lipid metabolism of Pekin ducks and hepatocytes were cultured in vivo for verification.Results:Dietary Met deficiency caused growth depression and excess fat deposition that were ameliorated by feeding diets with adequate Met.Serum triglyceride and non-esterified fatty acid concentrations increased(P<0.05),whereas serum concentrations of total cholesterol,low density lipoprotein cholesterol,total protein,and albumin decreased(P<0.05)in Met-D ducks compared to those in Met-A ducks.Based on hepatic proteomics analyses,dietary Met deficiency suppressed expression of key proteins related to fatty acid transport,fatty acid oxidation,tricarboxylic acid cycle,glycolysis/gluconeogenesis,ketogenesis,and electron transport chain;selected key proteins had similar expression patterns verified by qRT-PCR and Western blotting,which indicated these processes were likely impaired.In vitro verification with hepatocyte models confirmed albumin expression was diminished by Met deficiency.Additionally,in abdominal fat,dietary Met deficiency increased adipocyte diameter and area(P<0.05),and down-regulated(P<0.05)of lipolytic genes and proteins,suggesting Met deficiency may suppress lipolysis in adipocyte.Conclusion:Taken together,these data demonstrated that dietary Met deficiency in Pekin ducks resulted in stunted growth and excess fat deposition,which may be related to suppression of fatty acids transportation and hepatic catabolism.

Histopathology of Ducks Experimentally Infected with a Highly Pathogenic Avian Influenza Virus,A/duck/Guangdong/220/2004(H5N1)

Ducks inoculated intravenously or via the ocular-nasal-oral-cloacal routes with a highly pathogenic avian influenza virus,A/duck/Guangdong/220/2004(H5N1),developed systemic hyperemia,congestion,hemorrhage,thrombosis and edema in various organs,as well as necrosis or apoptosis in the parenchyma of the heart,liver,spleen,lungs,kidneys,pancreas,brain,thymus and bursa of Fabricius.The main manifestations were angiitis,necrotic pancreatitis,atrophic necrotic thymitis and bursitis Fabricii,splenitis,tracheitis,hemorrhagic bronchointerstitial pneumonia,viral myocarditis,nonsuppurative encephalitis,focal viral hepatitis,ulcerative enteritis,renal tubule interstitial nephritis,and intraglomerular mesangial cell hyperplastic glomerular nephritis.The results demonstrated that the mechanism of pathogenesis involved cellular necrosis and apoptosis,and that death of the ducks was caused by severe pathologic trauma occurring in multiple visceral organs.