Muscovy ducks (Cairina moschata) exhibit strong nesting tendencies, which result in reduced egg-laying performance. The research team previously identified differential expression of the Ras homolog family member B (RHOB) gene in the ovaries of Muscovy duck during the nesting and laying periods through RNA-seq and quantitative real-time polymerase chain reaction (qPCR) analysis. This finding suggested that RHOB may be associated with nesting behavior in Muscovy ducks. Previous studies have demonstrated that the nesting behavior of Muscovy ducks is closely associated with the proliferation and apoptosis of their ovarian granulosa cells. It is speculated that RHOB may be involved in the proliferation and apoptosis of Muscovy duck ovarian granulosa cells. This study employed qPCR, immunofluorescence staining, live-cell Caspase3 activity and mitochondrial membrane potential assays, reactive oxygen species (ROS) staining, 5-Ethynyl-2'-deoxyuridine (EdU) staining, cell cycle analysis, cell apoptosis detection and cell counting kit-8 (CCK-8) assays. Our results showed that RHOB inhibited granulosa cell apoptosis and promoted granulosa cell proliferation. Similarly, in a granulosa cell apoptosis model, RHOB was also found to inhibit apoptosis in Muscovy duck granulosa cells. Further studies revealed that RHOB regulates mitochondrial function in granulosa cells. The combined experimental results indicate that RHOB regulates granulosa cell apoptosis in Muscovy duck follicles via the mitochondrial apoptosis pathway. These findings provide an experimental basis and theoretical foundation for the selective breeding of desirable traits in Muscovy ducks, such as low nesting behavior and high egg production.

The intense broody behavior of Muscovy ducks (Cairina moschata) is a substantial negative impact on the efficiency of egg production. Forkhead box O3 (FOXO3) is a key regulator of female reproduction. It can enhance ovarian functions such as ovulation and follicle development. This study aimed to investigate the differential expression of FOXO3 between laying and broody ducks, to characterize its regulatory effects on granulosa cells (GCs) function, and to evaluate its potential as a molecular breeding marker for reducing broodiness. Quantitative real-time PCR (RT-qPCR) analysis demonstrated that FOXO3 expression was significantly higher in ovarian tissues of laying Muscovy ducks (LD) compared to broody Muscovy ducks (BD) (P<0.01). FOXO3 expression was also significantly higher in larger developing follicles (>6 mm) than in follicles measuring 2-6 mm. Enzyme-Linked Immunosorbent Assay (ELISA) results showed that serum prolactin (PRL) levels were significantly higher in BD than in LD group (P<0.01). Functional assays were performed in primary granulosa cells (GCs) using FOXO3 overexpression and siRNA-mediated knockdown. Overexpression of FOXO3 inhibited GCs proliferation, markedly increased the Caspase3, BAX/BCL2 protein ratio (P<0.01), and enhanced cellular apoptosis level (P<0.01). FOXO3 overexpression also significantly increased the autophagy-related proteins LC3 (P<0.01) and Beclin1 (P<0.05), while downregulating hormone‑related genes specifically expressed in GCs (StAR, CYP11A1, FSHR, ESR2, LHR). Further investigation showed that high FOXO3 expression increased AKT1 phosphorylation. Conversely, FOXO3 knockdown downregulated mRNA levels of apoptosis and autophagy‑related genes, including Caspase3, BAX, LC3, Beclin1, and FasL, with corresponding reductions in LC3 (P<0.01) and Beclin1 (P<0.05) protein levels. Hormone‑related genes (CYP11A1, FSHR, ESR2) and p-AKT1 protein levels showed minimal change under low FOXO3 expression. These findings suggest that high levels of FOXO3 increase AKT1 phosphorylation, regulate GCs apoptosis and influence the expressional level of hormone-related genes in Muscovy duck follicles. FOXO3 regulates the GCs apoptosis in follicles, as well as follicular development. This provides novel insights into its role in reducing broody behavior and potential applications in Muscovy duck breeding.

Body size remains a major trait due to its high economic impact for breeding selection. This study was aimed to select high-yielding Jinding ducks based on body size and physiological indicators. A total of 264 Jinding ducks were measured for eleven body size measurements and body weight, as well as seven hormones and four biochemical indicators (high-yielding duck, HYD, n = 132; low-yielding duck, LYD, n = 132). All data were subjected to t-tests and Pearson correlation analysis. The results revealed that HYD exhibited higher levels of gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), progesterone (PROG), testosterone (T), estradiol (E2), glucose (GLU), and triglyceride (TG) (P < 0.01) while lower levels of prolactin (PRL) (P < 0.01) compared with LYD. The HYD showed wider pubic spacing, slender necks, and longer keel bones than LYD (P < 0.01). The HYD also had wider body slope length, half-diving depth, chest depth, chest width, and tibia length (P < 0.05). Thus, based on the significant differences in body size and hormone levels, we further investigated the association between them. The result showed that the pubic spacing and neck length were positively correlated with GnRH, FSH, and PROG (P < 0.01) and negatively correlated with PRL (P < 0.05), while the keel bone length was positively correlated with GnRH, FSH (P < 0.01) and E2, PROG (P < 0.05).The half-diving depth was positively correlated with GnRH, E2 (P < 0.01) and LH, PROG (P < 0.05). This study provided breeding strategies and showed that HYD could be selected by wide pubic spacing, long keel bones and slender necks.

实验旨在探究生长分化因子 9(Growth Differentiation Factor,GDF9)基因对番鸭颗粒细胞的影响,本研究构建了GDF9过表达载体(pEX-2-GDF9)以及干扰GDF9小RNA(siRNA-GDF9-530、siRNA-GDF9-978、siRNA-GDF9-1320),分别转染至原代番鸭颗粒细胞内,通过流式细胞术检测GDF9基因对细胞周期和凋亡的影响;荧光定量PCR技术检测转染后颗粒细胞周期和凋亡相关基因的表达量.结果显示,过表达GDF9基因将番鸭颗粒细胞阻滞在G0/G1 期,S期细胞极显著减少,且Bax基因和Caspase-3基因表达量极显著(或显著)上调,说明过表达GDF9促进了颗粒细胞凋亡;干扰GDF9基因表达后,G0/G1期细胞极显著减少,S期细胞极显著增加,且CDK-2、Bcl-2、CCND1 mRNA极显著上调,CCNE1 mRNA显著上调.综上可知,GDF9基因表达促进颗粒细胞凋亡、抑制细胞周期进程.该结果可为番鸭的卵泡发育机制研究提供理论基础.

In order to analyze the relationship between organic matrix and eggshell properties in Muscovy duck eggshells with different qualities, the organic matrices in the eggshells of normal, pimpled and striped eggs of white-feathered Muscovy ducks were extracted and separated into acid-insoluble, water-insoluble and facultative-soluble matrix (both acid- and water-soluble). There was no significant difference in calcified shell thickness between normal and pimpled eggs. However, the percentages of acid-insoluble matrix and total matrix were significantly higher, and the breaking strength was significantly lower in pimpled eggs than those in normal eggs. In striped eggs, the percentages of acid-insoluble matrix, facultative-soluble matrix and total matrix, calcified shell weight, calcified shell thickness and breaking strength were significantly lower than those in normal eggs. The amount and percentage of 3 organic matrices (water-insoluble matrix, facultative-soluble matrix, and total matrix) were significantly positively correlated with calcified shell thickness in normal eggs rather than striped and pimpled eggs. Our results also demonstrated that there was no linear correlation between the organic components in the 3 Muscovy duck eggshells and the mechanical properties of the eggshells. The lower breaking strength of pimpled eggshells might be due to the unbalanced enrichment of certain proteins, whereas the striped eggs might mainly result from thinner calcified shells and poor balance between different sedimentary layers.

[目的]对番鸭(Cairina moschata)生长分化因子9(growth differentiation factor 9,GDF9)基因进行克隆及结构和功能的预测,并检测其在就巢期和产蛋期番鸭各组织中的表达差异.[方法]以番鸭卵巢组织eDNA为模板,利用快速扩增cDNA末端(rapid-amplification of eDNA ends,RACE)技术对GDF9基因进行扩增和克隆,利用生物信息学软件对GDF9基因的编码序列进行相似性分析和进化树构建,分析其基本理化性质和编码氨基酸序列的结构特征.利用实时荧光定量PCR技术检测就巢期番鸭和产蛋期番鸭各组织中GDF9基因的相对表达量.[结果]GDF9基因CDS区全长1380 bp,编码459个氨基酸;番鸭GDF9基因序列与GenBank已公布的凤头潜鸭、绿头鸭、天鹅、棕硬尾鸭、浙东白鹅、企鹅、鸡、牛、绵羊、猪和小鼠对应序列的相似性依次为98.8％、97.5％、96.4％、95.8％、94.4％、90.2％、87.5％、64.5％、64.2％、63.9％和60.6％.系统进化树结果显示,番鸭与凤头潜鸭和绿头鸭的亲缘关系较近,与小鼠的亲缘关系较远.GDF9蛋白分子质量为52.81 ku,是一种不稳定的碱性亲水膜外蛋白,有1个信号肽,含有45个磷酸化位点,8个O-糖基化位点,3个N-糖基化位点,存在1个转化生长因子-β(TGF-β)结构域;蛋白质的二级结构由无规则卷曲、α-螺旋、T-转角和β-折叠构成,所占比例分别为58.61％、22.22％、16.56％和2.61％.GDF9蛋白三级结构预测结果与二级结构一致.GDF9蛋白可能与BMP15、BMPR1B、BMPR2、TGFBR1、ACVR1B、POF1B、ZP2、ZAR1和MOS蛋白存在相互作用.实时荧光定量PCR结果显示,就巢期和产蛋期番鸭各组织中均有GDF9基因的表达,其中两个时期卵巢中的表达量均最高,且均极显著高于同一时期其他组织基因表达量(P＜0.01).同一组织不同时期相比,就巢期番鸭GDF9基因在脾脏、心脏和肾脏的表达量显著或极显著低于产蛋期(P＜0.05;P＜0.01),在卵巢中的表达量极显著高于产蛋期(P＜0.01),其他组织中的表达量在两个时期间差异均不显著(P＞0.05).[结论]本研究成功克隆番鸭GDF9基因,GDF9基因在番鸭各组织中均有表达,GDF9基因为番鸭产蛋期和就巢期卵巢、心脏、肾脏和脾脏的差异表达基因.该研究为进一步探索番鸭GDF9基因的功能提供了理论依据,也为研究GDF9基因在卵巢发育中的生物学功能及其分子机制奠定基础.

为了探究Struthiocalcin-2(SCA-2)基因在山麻鸭蛋壳形成过程中的作用,试验选择9只产蛋高峰期(30周龄)的健康山麻鸭,采用SMART-RACE方法对山麻鸭SCA-2基因cDNA序列进行克隆,运用生物信息学软件对SCA-2基因编码蛋白质的理化性质、二级和三级结构进行预测及分析,构建SCA-2基因系统进化树;采集试验山麻鸭心脏、肝脏、脾脏、肺脏、肾脏、胸肌、肌胃、下丘脑、垂体、卵巢,以及输卵管的漏斗部、膨大部、峡部和子宫部共14个组织,每3只做一次混样处理,每个组织共3个重复,提取组织RNA,通过实时荧光定量PCR分析SCA-2基因mRNA在上述组织中的相对表达量.结果表明:SCA-2基因的cDNA全长为726 bp,该基因编码蛋白的分子式为C836H1247 N229O247S8,属于不稳定蛋白,其中丝氨酸(12.6％)、亮氨酸(12.0％)、丙氨酸(10.2％)含量较高;蛋白质的二级结构中,α螺旋占23.35％、β折叠占13.77％、无规卷曲占62.87％,且包含信号肽序列,不含跨膜结构;山麻鸭与绿头鸭、凤头潜鸭和棕硬尾鸭的亲缘关系最近;SCA-2基因在山麻鸭14种组织中均有不同程度的表达,其中在输卵管子宫部和峡部组织中的表达量极显著高于卵巢(P＜0.01),明显高于其他组织.说明本试验成功克隆到了 SCA-2基因,该基因可能在山麻鸭蛋壳的形成过程中扮演着重要角色.

实验旨在探究OC-116(Ovocleidin-116)基因在山麻鸭蛋壳形成过程中的作用,应用SMART-RACE技术克隆获得了长度为2129 bp的山麻鸭OC-116基因cDNA全长序列,运用生物信息学软件对该基因和蛋白的特征进行分析,结果显示:该基因编码蛋白的分子式为C2710H4331N865O927S12,属于不稳定蛋白,其编码的蛋白中甘氨酸(16.5％)、丙氨酸(11％)、丝氨酸(10.2％)含量较高.蛋白的二级结构中,α螺旋(Hh)占比0.47％、β折叠(Ee)占比17.64％、无规卷曲(Cc)占比81.89％,且包含肽信号,不含跨膜结构;系统进化树显示山麻鸭与绿头鸭、黑天鹅和棕硬尾鸭的亲缘关系最近;在mRNA的水平上,OC-116基因在山麻鸭14种组织中均有不同程度的表达,其中在垂体、子宫部和峡部中的表达量极显著高于其他组织.子宫部和峡部分别是蛋壳矿化形成和蛋壳膜形成部位,表明OC-116基因在山麻鸭蛋壳的形成过程中扮演着重要的角色.

There are recent reports of the important functions of long noncoding RNAs (lncRNAs) in female reproductive and ovarian development. Studies in which there was characterization of lncRNAs in the ovaries of laying compared with nesting poultry, however, are limited. In this study, RNA libraries were constructed by obtaining sequencing data of ovarian tissues from laying and nesting Muscovy ducks. In the ovarian tissues of Muscovy ducks, a total of 334 differentially abundant mRNA transcripts (DEGs) and 36 differentially abundant lncRNA transcripts were identified in the nesting period, when compared with during the laying period. These results were subsequently validated by qRT-PCR using nine randomly-selected lncRNAs and six randomly-selected DAMTs. Furthermore, the cis- and trans-regulatory target genes of differentially abundant lncRNA transcripts were identified, and lncRNA-gene interaction networks of 34 differentially abundant lncRNAs and 263 DEGs were constructed. A total of 7601 lncRNAs neighboring 10,542 protein-coding genes were identified and found to be enriched in the Wnt signaling pathway and oocyte meiosis pathways associated with follicular development. Overall, only 11 cis-targets and 57 mRNA-mRNA except trans-targets were involved in the lncRNA-gene interaction networks. Based on the interaction networks, nine DEGs were trans-regulated by differentially abundant lncRNAs and 20 differentially abundant lncRNAs were hypothesized to have important functions in the regulation of broodiness in Muscovy ducks. In this study, a predicted interaction network of differentially abundant lncRNAs and DEGs in Muscovy ducks was constructed for the first time leading to an enhanced understanding of lncRNA and gene interactions regulating broodiness.

试验旨在建立番鸭等级前卵泡颗粒细胞的体外培养模型,为研究番鸭的就巢性和提高产蛋性能提供试验基础.在体外分离培养番鸭小黄卵泡颗粒细胞,探究不同的消化酶(12.5 g/mLⅡ型胶原酶、0.1％Ⅱ型胶原酶和0.25％胰蛋白酶)、消化时间(3 min、5 min、8 min、10 min、15 min、20 min、25 min、30 min和40 min)和血清浓度(含0.5％、1％、2.5％、5％和10％ FBS的M199完全培养液)对颗粒细胞增殖的影响,筛选最佳消化体系和培养体系.结果 显示:用0.1％的Ⅱ型胶原酶在37℃、5％ CO2培养箱中消化8～10 min可获得较优的颗粒细胞;对于刚分离到的颗粒细胞用含0.5％ FBS的M199完全培养液先培养24 h后换成无血清的培养液培养,既能维持增殖活性和细胞形态,又能满足后续试验的需要.

Much attention has been paid to the broodiness of the Muscovy duck, but the molecular mechanism of broodiness remains largely unknown. In this study, the ovary tissues of Muscovy ducks during the broody and laying periods were used to investigate differentially expressed proteins (DEPs) by the iTRAQ-based proteomics approach. A total of 335 DEPs were identified, including 139 up-regulated and 196 down-regulated proteins. Six proteins (APOV1, GAL, SAA, GNB5, VLDLR and CDK1) with higher changes in expression were selected, and these proteins are mainly involved in the pathways related to reproductive performance, such as Oocyte meiosis, and PI3K-Akt signaling pathway. Steroid biosynthesis was the most significantly enriched pathway by KEGG pathway enriched analysis. The qRT-PCR analysis was applied to verify the proteomic analysis. Meanwhile, metabolomics analysis found that several important differentially expressed metabolites (DEMs) (7-dehydrodesmosterol, 25-Hydroxyvitamin D3, 7-Dehydrocholesterol, Pregnanolone, Allopregnanolone and estrogen) that were also mainly involved in Steroid biosynthesis, Steroid hormone biosynthesis and Metabolic pathways. Crucially, the changes in the abundance of these metabolites are closely related to the changes in the protein abundance of proteins identified in the same pathway, and it is always the upstream key enzymes that influence the production of downstream metabolites.

为探索番鸭等级前卵泡发育过程中主要生殖激素及卵泡发育的变化规律,试验以同批孵化、饲养条件相同、体况相近的产蛋期番鸭为对象,分别采集小白卵泡(SWF)、大白卵泡(LWF)、小黄卵泡(SYF)、大黄卵泡(LYF).通过组织形态学方法观测卵泡的发育情况,酶联免疫吸附试验(ELISA)测定激素水平.结果表明:在等级前卵泡发育过程中,促卵泡素(FSH)和促黄体素(LH)呈现上升的趋势,且LYF时期浓度最高,差异不显著(P＜0.05);而孕酮(P4)和雌二醇(E2)均呈现下降趋势,从SWF至SYF时期极显著下降(P＜0.01),SYF至LYF时期,下降不显著(P＞0.05).伴随卵泡的发育,颗粒细胞层和卵泡膜层不断增厚,且卵泡膜厚度在LWF至LYF时期增长极显著(P＜0.01).由此可见,FSH、LH、P4、E2在番鸭等级前卵泡发育中起重要作用,且SYF阶段是番鸭等级前卵泡发育的关键阶段.

The green eggshell color produced by ducks is a threshold trait that can be influenced by various factors, such as hereditary, environment and nutrition. The aim of this study was to investigate the genetic regulation of the formation of eggs with green shells in Youxian ducks. We performed integrative analysis of mRNAs and miRNAs expression profiling in the shell gland samples from ducks by RNA-Seq. We found 124 differentially expressed genes that were associated with various pathways, such as the ATP-binding cassette (ABC) transporter and solute carrier supper family pathways. A total of 31 differentially expressed miRNAs were found between ducks laying green eggs and white eggs. KEGG pathway analysis of the predicted miRNA target genes also indicated the functional characteristics of these miRNAs; they were involved in the ABC transporter pathway and the solute carrier (SLC) supper family. Analysis with qRT-PCR was applied to validate the results of global gene expression, which showed a correlation between results obtained by RNA-seq and RT-qPCR. Moreover, a miRNA-mRNA interaction network was established using correlation analysis of differentially expressed mRNA and miRNA. Compared to ducks that lay white eggs, ducks that lay green eggs include six up-regulated miRNAs that had regulatory effects on 35 down-regulated genes, and seven down-regulated miRNAs which influenced 46 up-regulated genes. For example, the ABC transporter pathway could be regulated by expressing gga-miR-144-3p (up-regulated) with ABCG2 (up-regulated) and other miRNAs and genes. This study provides valuable information about mRNA and miRNA regulation in duck shell gland tissues, and provides foundational information for further study on the eggshell color formation and marker-assisted selection for Youxian duck breeding.

表皮生长因子(EGF)是表皮上生长家族的重要调节因子之一,可促进细胞增殖分化、调控细胞的衰老以及诱导肿瘤的发生.在动物卵巢卵泡的研究中发现,EGF可以有效地抑制卵泡细胞的凋亡、促进颗粒细胞的增殖和卵母细胞的成熟,因此近年来受到了越来越多的学者的关注.为了进一步认识EGF基因对各级卵泡的调节作用,文章拟从EGF基因的结构、对卵泡发育的作用机理等角度进行阐述,为研究EGF基因参与调控动物卵泡发育过程的作用机制提供参考.

本试验以金定鸭、褐色菜鸭和攸县麻鸭为素材,在相同的饲养管理和孵化条件下,对3个蛋鸭品种的产蛋性能、青壳率、受精率、受精蛋孵化率和不同阶段体重进行观测.结果表明:3个蛋鸭品种中攸县麻鸭300日龄产蛋量(144个)最高,见蛋日龄(96d)和开产日龄(123d)最早,因此3个蛋鸭品种中以攸县麻鸭产蛋性能最好;褐色菜鸭和攸县麻鸭公、母鸭30日龄体重、开产体重、300日龄蛋重差异均不显著(P＞0.05),由此可见,褐色菜鸭与攸县麻鸭属于同一类型蛋鸭品种.3个蛋鸭各品种的入孵蛋重与出壳重均呈极显著正相关(P＜0.01).

【Objective】 The objective of this experiment is to identify differentially expressed genes of Muscovy Duck broodiness.【Method】cDNA-AFLP approach was employed to analyze genes differentially expressed in broodiness and non-broodiness Muscovy Duck individuals derived from a single RF white feathers line.【Result】 There were 82 differentially expressed bands associated with broodiness behaviors,15 bands of them were subject to sequence analysis.Database searches indicate that 8 cDNA fragments show high homology to known genes,which include some function genes in hypothalamic-pituitary-gonadal axis regulating reproduction,such as GnRH gene and FSH gene.Meanwhile genes were also found in GH-IGF axis,such as GH gene.Other genes participated in signal transduction,transcription,metabolism biological processes,such as superoxide dismutase,keratin related protein,thiocyanate enzyme release S-transferase enzymes etc.Two cDNA fragments show homology to unknown function genes,5 cDNA fragments show no detectable homology to know genes,suggesting that they probably represent novel genes.Three bands selected randomly from them were confirmed by RT-PCR and that result was consistent with the results of cDNA-AFLP.【Conclusion】 The results of this paper uncovered the regulation mode of gene express variation of different Muscovy Duck broodiness traits,and thus further providing the molecular mechanism of broodiness of Muscovy Duck.

促性腺激素释放激素(GnRH)和生长激素(GH)分别是下丘脑-垂体-性腺轴(HPG)与GH/IGF轴分泌的激素,共同参与调控动物的繁殖性能.本研究以白羽番鸭(Cairina moschata)RF系为实验材料,采用PCR-SSCP技术进行基因分型,同时建立适合的线性统计模型,分析基因型与产蛋性能的关联性.结果表明,GnRH基因5’调控区检测到3种基因型AA/AB/BB,经测序比对AA型与BB型相比发生G→A突变,不同基因型与300日龄产蛋数和最大连产天数均显著相关(P＜0.05),与开产日龄无显著相关(P＞0.05); GH基因内含子3检测到3种基因型CC/CD/DD,经测序比对CC型与DD型相比发生A→G突变,不同基因型与最长连产天数显著相关(P＜0.05),与300日龄产蛋数和开产日龄均无显著相关(P＞0.05).两个基因发挥作用的方式主要为加性效应,GnRH基因对300日龄产蛋数和最大连产天数的加性效应值分别为-3.53和-3.33,GH基因对最大连产天数的加性效应值为-2.44.推测GnRH和GH基因是与繁殖主效基因紧密连锁的标记基因.

The cDNA amplified fragment length polymorphism(cDNA-AFLP) analysis system of muscovy duck was established using pituitary as materials.The first single strand cDNA was gained through the reverse transcription from the total RNA.The second strand cDNA was synthesized by using RNase H and DNA polymerase I DNA.Double-stranded cDNA was digested completely after 2 h digestion by EcoRⅠ and MseⅠ step by step,and ligated to two adapters by T4 DNA ligase.The pre-amplification diluted to 40 times for selective amplification.The results of 1% agarose gel electrophoresis and 6% denaturing polyacrylamide gel electrophresis(PAGE) indicated that the RNA extraction,cDNA-AFLP pre-amplification and select-amplification by above procedures were effective.The cDNA-AFLP analysis system was established successfully,which provided platform for molecular mechanism of broodiness of muscovy duck.

自组织映射神经(Self-organizing maps,SOM)网络是一种无监督学习方法,具有良好的自组织、可视化等特性,现已广泛应用于各个领域。本文介绍了SOM网络在基因组序列分析、单核苷酸多态性检测、基因表达数据分析以及蛋白质结构预测和分类中的应用,同时展望了SOM网络在生物信息学中的应用前景。

In this study,Liancheng ducks were used to analyze single nucleotide polymorphism (SNP) in 5′ regulatory region of GnRH gene by PCR-SSCP,and the correlation between the gene and laying traits had been discussed. The result indicated that there were three genotypes (AA,BB,AB) in Liancheng duck and the genotypes showed there was a significant difference in the number of eggs(300 days of age)(P﹤0.05) and no significant difference in age at first egg (P﹥0.05). It implied that GnRH gene could be used as a molecular mark to screen egg number in Liancheng duck.