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.

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.

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.

Strategies to improve genomic predictions for 35 duck carcass traits in an F2 population

Background Carcass traits are crucial for broiler ducks,but carcass traits can only be measured postmortem.Genomic selection(GS)is an effective approach in animal breeding to improve selection and reduce costs.However,the performance of genomic prediction in duck carcass traits remains largely unknown.Results In this study,we estimated the genetic parameters,performed GS using different models and marker densi-ties,and compared the estimation performance between GS and conventional BLUP on 35 carcass traits in an F2 population of ducks.Most of the cut weight traits and intestine length traits were estimated to be high and moder-ate heritabilities,respectively,while the heritabilities of percentage slaughter traits were dynamic.The reliability of genome prediction using GBLUP increased by an average of 0.06 compared to the conventional BLUP method.The Permutation studies revealed that 50K markers had achieved ideal prediction reliability,while 3K markers still achieved 90.7%predictive capability would further reduce the cost for duck carcass traits.The genomic relationship matrix nor-malized by our true variance method instead of the widely used 2pi(1-pi)could achieve an increase in prediction reliability in most traits.We detected most of the bayesian models had a better performance,especially for BayesN.Compared to GBLUP,BayesN can further improve the predictive reliability with an average of 0.06 for duck carcass traits.Conclusion This study demonstrates genomic selection for duck carcass traits is promising.The genomic prediction can be further improved by modifying the genomic relationship matrix using our proposed true variance method and several Bayesian models.Permutation study provides a theoretical basis for the fact that low-density arrays can be used to reduce genotype costs in duck genome selection.

Inhibitory effect of coriander(Coriandrum sativum L.)extract marinades on the formation of polycyclic aromatic hydrocarbons in roasted duck wings

Coriander(Coriandrum sativum L.)is recognized for its antioxidant property,as a kind of natural phenolic-rich ingredient.Polycyclic aromatic hydrocarbons(PAHs)present a class of heat-driven hazards in foods,especially the processed meat.In this study,the effect of coriander root and leaf extract on the formation and inhibition of PAH8 in roasted duck wings was firstly investigated.Coriander root extract(CRE)and coriander leaf extract(CLE)with five concentration groups(200,400,600,800,1000 mg/L)were prepared respectively to marinate the duck wings.CRE marinade exhibited greater inhibitory effect on PAH8 formation in roasted duck wings that ranged from 65.0%-87.4%.The electron spin resonance study indicated a significantly positive correlation between PAH8 and free radical level,suggesting the participation of radicals in PAHs formation.Also,it was speculated that the inhibitory effect on PAH8 was related to the phenolic compounds identified in coriander marinades.CRE made greater inhibitory effect on the formation of PAH8 and could be considered as a kind of natural source to mitigate PAHs in heat-processed meat products.

FMO3 deficiency of duck leads to decreased lipid deposition and increased antibacterial activity

Background:Most duck eggs possess a fishy odor,indicating that ducks generally exhibit impaired trimethylamine(TMA)metabolism.TMA accumulation is responsible for this unpleasant odor,and TMA metabolism plays an essen-tial role in trimethylaminuria(TMAU),also known as fish odor syndrome.In this study,we focused on the unusual TMA metabolism mechanism in ducks,and further explored the unclear reasons leading to the debilitating TMA metabolism.Methods:To achieve this,transcriptome,proteome,and metagenome analyses were first integrated based on the constructed duck populations with high and low TMA metabolism abilities.Additionally,further experiments were conducted to validate the hypothesis regarding the limited flavin-containing monooxygenase 3(FMO3)metabolism ability of ducks.Results:The study demonstrated that liver FMO3 and cecal microbes,including Akkermansia and Mucispirillum,par-ticipated in TMA metabolism in ducks.The limited oxidation ability of FMO3 explains the weakening of TMA metabo-lism in ducks.Nevertheless,it decreases lipid deposition and increases antibacterial activity,contributing to its survival and reproduction during the evolutionary adaptation process.Conclusions:This study demonstrated the function of FMO3 and intestinal microbes in regulating TMA metabolism and illustrated the biological significance of FMO3 impairment in ducks.

Roast Duck in Zhengzhou

When we talk about roast duck,most of the people would think of Beijing Roast Duck.Yes,Beijing Roast Duck is delicious definitely.However,today I’d like to talk about Zhengzhou Roast Duck,which is in my hometown.The most famous restaurant of roast duck in Zhengzhou is located in Renmin Road.Many people in Zhengzhou and the tourists who come to Zhengzhou would like to taste the roast duck there.

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 effects of the dietary inclusion of partially defatted Hermetia illucens larva meal in Muscovy duck

Background: The present work is aimed at evaluating the effect of different inclusion levels of a partially defatted black soldier fly(Hermetia illucens,L.;HI) larva meal for ducks.A total of 192 female 3-day-old Muscovy ducklings(Cairina moschata domestica,Canedins R71 L White,Grimaud Freres Selection,France) were divided into 4 groups,assigned 4 different dietary treatments(6 replicates/treatment and 8 birds/replicate) and reared from 3 to 50 days of age.HI larva meal was included at increasing levels(0,3%,6% and 9%,HI0,HI3,HI6 and HI9,respectively) in isonitrogenous and isoenergetic diets formulated for 3 feeding phases: starter(3–17 days of age),grower(18–38 days of age) and finisher(39–50 days of age).The growth performance and apparent total tract digestibility were evaluated during the trial using titanium dioxide as an inert marker(0.3% of inclusion).At 51 days of age,two birds per pen were slaughtered and histomorphological investigations were performed.Results: The live weight and average daily gain showed a quadratic response to increasing HI meal in the grower period(minimum corresponding to the HI6 group).No effects of dietary inclusion levels were observed for the daily feed intake or feed conversion ratio.The apparent dry matter and organic matter digestibility were not affected by the dietary treatment.A linear decrease was observed for the crude protein apparent digestibility in the starter period(minimum for the HI9 groups).The ether extract apparent digestibility increased linearly during the grower and finisher periods(minimum for the HI0 group).The morphometric indices were not influenced by the dietary treatments.Conclusions: The inclusion of up to 9% of HI partially defatted larva meal in the diet of ducks did not cause any effect on growth performance,as well as the apparent digestibility.Moreover,dietary HI inclusion preserved the physiological intestinal development.

Performance of a water hyacinth(Eichhornia crassipes)system in the treatment of wastewater from a duck farm and the effects of using water hyacinth as duck feed

Nowadays, intensive breeding of poultry and livestock of large scale has made the treatment of its waste and wastewater an urgent environmental issue, which motivated this study. A wetland of 688 mz was constructed on an egg duck farm, and water hyacinth （Eichhornia crassipes） was chosen as an aquatic plant for the wetland and used as food for duck production. The objectives of this study were to test the role of water hyacinth in purifying nutrient-rich wastewater and its effects on the ducks＇ feed intake, egg laying performance and egg quality. This paper shows that the constructed wetland removed as much as 64.44% of chemical oxygen demand （COD）, 21.78% of total nitrogen （TN） and 23.02% of total phosphorus （TP）. Both dissolved oxygen （DO） and the transparency of the wastewater were remarkably improved, with its transparency 2.5 times higher than that of the untreated wastewater. After the ducks were fed with water hyacinth, the average daily feed intake and the egg-laying ratio in the test group were 5.86% and 9.79% higher, respectively, than in the control group; the differences were both significant at the 0.01 probability level. The egg weight in the test group was 2.36% higher than in the control group （P 〈 0.05）, but the feed conversion ratios were almost the same. The eggshell thickness and strength were among the egg qualities significantly increased in ducks fed with water hyacinth. We concluded that a water hyacinth system was effective for purifying wastewater from an intensive duck farm during the water hyacinth growing season, as harvested water hyacinth had an excellent performance as duck feed. We also discussed the limitations of the experiment.

Cloning and Sequence of Glycoprotein H Gene of Duck Plague Virus

The glycoprotein H （gH） gene homologue of duck plague virus （DPV） was cloned by degenerate polymerase chain reaction （PCR） and sequenced. It was located immediately downstream from the thymidine kinase gene （TK）. In addition, the 3＇-end of the gene homologue to herpesvirus UL21 was located downstream from the gH gene. DPV gH gene open reading frame （ORF） was 2 505 bp in length and its primary translation product was a polypeptide of 834 amino acids long. It possessed several characteristics of membrane glycoproteins, including an N-terminal hydrophobic signal sequence, an external domain containing eight putative N-linked glycosylation sites, a C-terminal transmembrane domain, and a charged cytoplasmic tail. Comparison with other herpesvirus revealed identities of 20.2, 25.1, 23.0, 23.0, 26.5 and 26.0% with the gH counterparts of the human herpesvirus virus 1 （HSV1）, equine herpesvirus 4 （EHV4）, bovine herpesvirus 1 （BHV1）, pseudorabies virus （PRV）, gallid herpesvirus 2 （GHV2） and gallid herpesvirus 3 （GHV3）, respectively.

Cloning of Thymidine Kinase Gene of Duck Plague Virus Using Degenerate PCR

The DNA of duck plague virus （DPV） thymidine kinase （TK） gene was cloned and sequenced from a vaccine virus in the study. Degenerate oligonucleotide primers for the consensus site of herpesvirus UL24, TK, and glycoprotein H（gH） gene were used in the polymerase chain reaction （PCR） to amplify DNA product with 3 741-base-pairs （bp） in size. DNA sequence analysis revealed a 1 077-base-pairs （bp） open reading frame （ORF） encoding a 358 amino acid polypeptide homologous to herpesvirus TK proteins. The predicted TK protein shared 31.2, 41.3, 35.7, 37.4, and 28.4% identity with herpes simplex virus typel, equine herpesvirus type 4, Marek＇s disease virus 2, herpesvirus turkey, and infectious laryngotracheitis virus, respectively. Comparison of the amino acid sequences of other herpesvirus TK proteins showed that these proteins were not conserved on the whole, otherwise the portion of the TK proteins corresponding to the nucleotide binding domain and the nucleoside binding site were highly conserved among herpesvirus. Comparison with the amino acid sequences of the conserved nucleotide and nucleoside binding domains of other eleven herpesvirus TK proteins to the predicted DPV peptide confirmed its identity as the DPV TK protein.

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.

Role of duck plague virus glycoprotein C in viral adsorption:Absence of specific interactions with cell surface heparan sulfate

Many mammalian herpes viruses utilize heparan sulfate （HS） moieties present on cell surface proteoglycans as receptors for cell entry, and this process also requires viral glycoprotein C （gC） homologues. However, our understanding of the role of gC in facilitating attachment of other alpha-herpes viruses such as the duck plague virus （DPV） remains preliminary. To study the role of gC during DPV infection, we used a gC-deleted mutant virus （DPV-AgC-EGFP）. Examination of the viral copy number by real-time PCR, as well as time course studies of viral adsorption and proliferation revealed that gC was involved in the viral binding to the cell surface. The affinity of viral glycoproteins （gB-DPV, gC-DPV, and gE-DPV） to HS was assessed using a prokaryotic expression system and HJTrapTM HeparJn HP column chromatography. In addition, to confirm that gC played a role in the interaction between DPV and HS, viruses were treated with the HS analogue heparin and host cells were treated with its inhibitors heparinase prior to exposure to DPV-△gC-EGFP or wild-type strain Chinese virulent duck plague virus （DPV-CHv）. The effects of heparin and heparinase on virus infectivity demonstrated that function of gC on Viral adsorption is independent of interactions between gC and heparin sulfate on cell surface. All in all, this study demonstrated that the gC of DPV can mediate viral adsorption in an HS-independent manner, which distinguish it from the gC of some other alpha-herpes viruses. Future studies will be required to identify the receptors involved in gC protein binding to cells. This work provides us a foundation for further studies of examining the roles of gC in the adsorption during duck plague virus infection.

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.

Effects of foraging site distances on the intestinal bacterial community compositions of the sympatric wintering Hooded Crane(Grus monacha)and Domestic Duck(Anas platyrhynchos domesticus)

Background:The composition of intestinal microflora in animals is affected by cross-species transmission.In a nature reserve,the foraging sites of waterbirds are relatively fixed,but frequently close to residential areas and can also be visited by domestic fowls.It is easy to result in the trans-species-flock dispersal of gut microbes between the wild birds and domestic fowls.The effects of the variable foraging site distances on the gut microbe structures of the waterbirds and the sympatric domestic fowls are currently unclear,and further research is required to evaluate the impacts of geographic location on cross-infection.Methods:Illumina high-throughput sequencing and bioinformatics analysis software were utilized to compare and analyze the composition of gut microbes from the fecal samples of Hooded Cranes(HC;Grus monacha)and two groups of Domestic Ducks(Anas platyrhynchos domesticus)that foraged at 1 km(ducks in near areas,D-N),and 4 km(ducks in far areas,D-F)away from the habitats of the Hooded Cranes at Shengjin Lake,China.Results:The results showed that there were significant differences in the alpha-diversity of the gut bacteria in the HC,D-N,and D-F samples under the interspecific distance factor.The dominant bacterial phyla,Cyanobacteria and Proteobacteria,showed correlations with distance for each host.The D-N group had more diverse intestinal flora than the D-F,as they were physically closer to the HC and had more indirect contact and cross-transmission of their gut microbes.More potentially pathogenic bacterial sequences,and Operational Taxonomic Units(OTUs)were found in the D-N than in HC and D-F.Conclusions:Hooded Cranes and the Domestic Duck populations at variable distances from the cranes showed significant differences in their intestinal bacteria and potentially pathogenic bacteria.The closer the foraging sites were,the easier the intestinal flora spread across species.The results provide a basis for determining the safe distance between wild birds and domestic fowls in a nature reserve.

Characterization of spoilage bacterial communities in chilled duck meat treated by kojic acid

Chilled duck meat is a popularly consumed meat in China but easily perishes at room/low temperature. Kojic acid is usually used as an antimicrobial. This study investigated the sensory scores, total bacteria number, and total volatile base nitrogen (TVB-N) value of chilled duck meat under kojic acid treatment during storage. The results presented that kojic acid suppressed the growth of spoilage bacteria and prolonged the shelf-life of chilled duck meat by at least two days. In further investigation, the bacterial community composition was explored through high-throughput sequencing. Pseudomonas spp. were the predominant spoilage bacteria after 6-day storage and were significantly suppressed by kojic acid. Besides, Brochothrix showed drug resistance and became the dominant bacteria in the kojic acid treated sample after 6-day storage. In conclusion, kojic acid maintained the sensorial, chemical, and microbial quality of duck meat stored at low temperatures. Meanwhile, kojic acid enriched the bacteria composition and showed strong antimicrobial activity against Pseudomonas spp.

Molecular Cloning of Myostatin Partial cDNA of Beijing Duck and Its Expression in Breast Muscle

In this experiment, 500 bp cDNA of myostatin gene was cloned from a Beijing duck＇s breast, The duck myostatin gene was found to have 98, 96, 95, 88, and 87% sequence similarity at the cDNA level with domestic goose, chicken, domestic pigeon, human, and pig, respectively. The predicted amino acid sequence has an overall similarity with a comparable region of turkey 99%, domestic goose 98%, and chicken 99%. Conserved domains of deduced amino acids showed that it belonged to the TGF-beta family. Myostatin expression in breast muscle was higher at 28, 35, and 42 days than at 7, 14, and 21 days. The pattern of myostatin expression was closely parallel to the trend of breast muscle growth, suggesting that myostatin might play an important role in breast muscle development. It was possible to postulate that myostatin may be a major determinant of muscle mass in breast muscle, as shown in other species.

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.