Application of SNP genetic marker affecting chicken body weight at first egg in genetic breeding of laying hens

Abstract

The application provides application of a SNP genetic marker affecting chicken body weight at the onset of lay in genetic breeding of laying hens, and belongs to the field of animal genetic breeding and biotechnology.The SNP genetic marker affecting chicken body weight at the onset of lay comprises bw1egg_1 and / or bw1egg_2; the Ensembl number of the bw1egg_1 is rs318020581, corresponding to the 76311052th position of the positive strand of chromosome 4 in the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 3rd intron of the gene C1QTNF7, and the base at the position is T or G; the Ensembl number of the bw1egg_2 is rs313708699, corresponding to the 74731889th position of the positive strand of chromosome 4 in the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 8th intron of the gene SLIT2, and the base at the position is T or C.Both the bw1egg_1 and the bw1egg_2 are helpful to genetically improve the body weight at the onset of lay, and when applied to genetic breeding of chickens, are favorable to improving the body weight at the onset of lay of the laying hens and obtaining a laying hen breed with excellent performance in uniformity of the body weight at the onset of lay.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of animal genetics and biotechnology, and particularly relates to application of a SNP genetic marker affecting chicken first-laying body weight in genetic breeding of laying hens. BACKGROUND

[0002] First-laying body weight is a common index for breeding laying hens, which can be used to identify whether the laying hen is sexually mature, measure the uniformity of the population, and predict the egg-laying performance. Studies have shown that there is a clear lower limit for the body weight of poultry, and a female bird below the threshold cannot enter sexual maturity. The first-laying of a chicken is a complex physiological development process, which is not only regulated by external environmental factors such as photoperiod, but also affected by genetic factors. Generally speaking, only by changing the frequency of related genes can we obtain lasting and cumulative progress. In recent years, the GWAS method has been extended to the genetic structure analysis of quantitative traits of laying hens, which is mainly used for the study of egg number, feed utilization efficiency and egg quality, and less used for the analysis of the genetic structure of the first-laying body weight of laying hens. In recent years, the GWAS method has been extended to the genetic structure analysis of quantitative traits of laying hens, which is mainly used for the study of egg number, feed utilization efficiency and egg quality, and less used for the analysis of the genetic structure of the first-laying body weight of laying hens. The first-laying body weight trait is regulated by multiple genes with small effects, and it is difficult to obtain effective progress from the genetic point of view by using conventional breeding methods. Only by clarifying the genetic structure of the first-laying body weight can we achieve the genetic influence on the first-laying body weight.

[0003] Dongxiang green-shell laying hens are originally from Dongxiang County and nearby areas in Jiangxi Province, and are a famous local egg-type chicken breed in China, and also a national geographical indication breed. Dongxiang green-shell laying hens are named for producing green-shell eggs, and have a long history of breeding in rural areas. They have a variety of traits, including black, white, yellow, and mottled feathers, black and white skin, and yellow, white, and purple ear leaves. After selection, Dongxiang green-shell laying hens can be used to construct Suqin green-shell laying hens and Shendan No. 6 green-shell laying hens, and play an important role in the egg market. Systematic study of the genetic structure of the first-laying body weight of Dongxiang green-shell laying hens is of great significance for the development and utilization of Dongxiang green-shell laying hens. The first-laying body weight is a late-life trait of living beings, and can only be measured at the time of first-laying, which increases the cost of breeding for breeding selection. Therefore, it is necessary to find suitable molecular markers to achieve early selection through genetic marker-assisted breeding or genomic selection, so as to quickly obtain genetic progress in the first-laying body weight of laying hens, and thus achieve the purpose of improving the uniformity of the first-laying body weight of laying hens.

[0004] In addition, Dongxiang green-shell laying hens do not perform well in production performance due to not having undergone high-intensity chicken breeding, especially in the coefficient of variation of the first-laying body weight, which is difficult to meet the needs of modern egg production. In order to meet the demand for green-shell eggs in the egg market and to tap the genetic resources of local chicken breeds in China, it is necessary to find new molecular markers to enrich the genetic marker library related to the first-laying body weight of chickens, so as to improve the first-laying body weight of the laying hen population from the genetic point of view. SUMMARY

[0005] In order to genetically improve the egg laying weight of laying hens, the application provides an application of a SNP genetic marker affecting the egg laying weight of chickens in genetic breeding of laying hens, and the SNP genetic markers bw1egg_1 and bw1egg_2 affecting the egg laying weight of chickens are helpful to genetically improve the egg laying weight, and are applied to genetic breeding of chickens, which is beneficial to improve the egg laying weight of laying hens and obtain a laying hen breed with excellent uniformity performance of egg laying weight.

[0006] The application is achieved by the following technical solutions:

[0007] The application provides an application of a SNP genetic marker affecting the egg laying weight of chickens in genetic breeding of laying hens, and the SNP genetic marker affecting the egg laying weight of chickens includes bw1egg_1 and / or bw1egg_2.

[0008] The Ensembl number of the bw1egg_1 is rs318020581, corresponds to the 76311052th position of the positive strand of chromosome 4 in the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI, belongs to the 3rd intron of the gene C1QTNF7, and the base at this position is T or G.

[0009] The Ensembl number of the bw1egg_2 is rs313708699, corresponds to the 74731889th position of the positive strand of chromosome 4 in the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI, belongs to the 8th intron of the gene SLIT2, and the base at this position is T or C.

[0010] Based on the same inventive concept, the application provides an early selection method for the egg laying weight trait of chickens, and the early selection method includes early selection for the egg laying weight trait of chickens based on the genotype of the SNP genetic marker bw1egg_1 and / or bw1egg_2.

[0011] The Ensembl number of the bw1egg_1 is rs318020581, corresponds to the 76311052th position of the positive strand of chromosome 4 in the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI, belongs to the 3rd intron of the gene C1QTNF7, and the base at this position is T or G.

[0012] The Ensembl number of the bw1egg_2 is rs313708699, corresponding to the sequence of the positive strand of chromosome 4 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b published in NCBI, which is the 8th intron of the gene SLIT2, and the base at this position is T or C.

[0013] Further, the early selection method specifically comprises:

[0014] detecting the genotype of the SNP genetic marker bw1egg_1 and / or bw1egg_2 of the test chicken;

[0015] early selecting the first egg weight trait of the test chicken based on the genotype of the bw1egg_1 and / or the bw1egg_2;

[0016] wherein the first egg weight of the individual with the TT genotype of the bw1egg_1 is higher than that of the individual with the TG genotype, and the first egg weight of the individual with the TG genotype is higher than that of the individual with the GG genotype.

[0017] The first egg weight of the individual with the CC genotype of the bw1egg_2 is higher than that of the individual with the TT and CT genotypes.

[0018] Further, the detection of the genotype of the SNP genetic marker bw1egg_1 and / or bw1egg_2 of the test chicken specifically comprises:

[0019] detecting the genotype of the SNP genetic marker bw1egg_1 and / or bw1egg_2 of the test chicken, wherein the method for detecting the genotype of the bw1egg_1 is as follows:

[0020] PCR amplification is performed on the genomic DNA of the test chicken by using Primer_asm1f and Primer_asm1r as primers;

[0021] sequencing the PCR amplification product to obtain the genotype of the test chicken at the position 76311052 of the positive strand of chromosome 4;

[0022] The method for detecting the genotype of the bw1egg_2 is as follows:

[0023] PCR amplification is performed on the genomic DNA of the test chicken by using Primer_asm2f and Primer_asm2r as primers;

[0024] sequencing the PCR amplification product to obtain the genotype of the test chicken at the position 74731889 of the positive strand of chromosome 4;

[0025] The nucleotide sequence of the Primer_asm1f is shown as SEQ ID NO. 1, the nucleotide sequence of the Primer_asm1r is shown as SEQ ID NO. 2; the nucleotide sequence of the Primer_asm2f is shown as SEQ ID NO. 3, and the nucleotide sequence of the Primer_asm2r is shown as SEQ ID NO. 4.

[0026] Further, the chicken to be detected includes Dongxiang green shell laying hen and / or Bailaihang chicken.

[0027] Based on the same inventive concept, the application provides an application of a reagent for detecting a SNP genetic marker affecting the body weight of a chicken at the onset of laying in the genetic breeding of a laying hen, wherein the SNP genetic marker affecting the body weight of a chicken at the onset of laying includes bw1egg_1 and / or bw1egg_2.

[0028] The Ensembl number of the bw1egg_1 is rs318020581, which corresponds to the 76311052th position of the positive strand of chromosome 4 in the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI, and belongs to the 3rd intron of the gene C1QTNF7, wherein the base is T or G.

[0029] The Ensembl number of the bw1egg_2 is rs313708699, which corresponds to the 74731889th position of the positive strand of chromosome 4 in the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI, and belongs to the 8th intron of the gene SLIT2, wherein the base is T or C.

[0030] Further, the reagent for detecting the SNP genetic marker affecting the body weight of a chicken at the onset of laying includes primers for detecting the bw1egg_1 and / or the bw1egg_2, wherein the primers for detecting the bw1egg_1 include Primer_asm1f and Primer_asm1r, and the primers for detecting the bw1egg_2 include Primer_asm2f and Primer_asm2r.

[0031] The nucleotide sequence of the Primer_asm1f is shown as SEQ ID NO. 1, the nucleotide sequence of the Primer_asm1r is shown as SEQ ID NO. 2; the nucleotide sequence of the Primer_asm2f is shown as SEQ ID NO. 3, and the nucleotide sequence of the Primer_asm2r is shown as SEQ ID NO. 4.

[0032] Based on the same inventive concept, the present application provides a kit for detecting SNP genetic markers affecting the body weight of a chicken at the onset of laying, the kit comprising primers for detecting bw1egg_1 and / or bw1egg_2, the primers for detecting bw1egg_1 comprising Primer_asm1f and Primer_asm1r, and the primers for detecting bw1egg_2 comprising Primer_asm2f and Primer_asm2r.

[0033] The nucleotide sequence of the Primer_asm1f is shown as SEQ ID NO. 1, the nucleotide sequence of the Primer_asm1r is shown as SEQ ID NO. 2, the nucleotide sequence of the Primer_asm2f is shown as SEQ ID NO. 3, and the nucleotide sequence of the Primer_asm2r is shown as SEQ ID NO. 4.

[0034] Based on the same inventive concept, the present application provides an application of the kit for detecting SNP genetic markers affecting the body weight of a chicken at the onset of laying in chicken genetic breeding.

[0035] Based on the same inventive concept, the present application also provides an application of SNP genetic markers affecting the body weight of a chicken at the onset of laying in predicting the body weight of a chicken at the onset of laying, the SNP genetic markers affecting the body weight of a chicken at the onset of laying comprising bw1egg_1 and / or bw1egg_2.

[0036] The Ensembl number of the bw1egg_1 is rs318020581, corresponding to the 76311052th position of the positive strand of chromosome 4 in the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 3rd intron of the gene C1QTNF7, and the base at this position is T or G.

[0037] The Ensembl number of the bw1egg_2 is rs313708699, corresponding to the 74731889th position of the positive strand of chromosome 4 in the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 8th intron of the gene SLIT2, and the base at this position is T or C.

[0038] The one or more technical solutions in the embodiments of the present application have at least the following technical effects or advantages:

[0039] The application of the SNP genetic marker affecting the body weight of a chicken at the onset of laying in the genetic breeding of laying hens, the SNP genetic marker affecting the body weight of a chicken at the onset of laying includes bw1egg_1 and bw1egg_2, and both are located on chromosome 4 of a chicken, and both bw1egg_1 and bw1egg_2 are associated with the body weight of a chicken at the onset of laying, and the population with the advantageous genotypes has a higher level of the body weight at the onset of laying, and the application of bw1egg_1 and / or bw1egg_2 in the genetic breeding of a chicken helps to genetically improve the level of the body weight at the onset of laying of a population of laying hens, and further obtain a breed of laying hens with excellent performance in the uniformity of the body weight at the onset of laying. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort.

[0041] Figure 1 Manhattan plot for GWAS analysis of the body weight at the onset of laying of the resource population in Embodiment 2 of the present application;

[0042] Figure 2 QQ plot for GWAS analysis of the body weight at the onset of laying of the resource population in Embodiment 2 of the present application;

[0043] Figure 3 Box plot of the body weight at the onset of laying of individuals with different genotypes in Embodiment 3 of the present application;

[0044] Figure 4 Box plot of the body weight at the onset of laying of individuals with different genotypes in Embodiment 4 of the present application. DETAILED DESCRIPTION

[0045] The advantages and various effects of the present application will be more clearly presented by the following specific embodiments and examples. Those skilled in the art should understand that these specific embodiments and examples are used to illustrate the present application, not to limit the present application.

[0046] Throughout this specification, unless otherwise specifically indicated otherwise, the terms used herein are to be understood as having the meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as generally understood by those skilled in the art to which the present application belongs. If there is a conflict, the present specification takes precedence.

[0047] Unless otherwise specifically indicated, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0048] The application of the SNP genetic marker affecting the body weight of the first egg laying of chickens in the genetic breeding of laying hens will be described in detail below with examples and experimental data.

[0049] Example 1

[0050] Resource population construction

[0051] In order to analyze the genetic structure of egg traits, a laying hen resource population was constructed according to the F2 design. Local chicken breed Dongxiang Green Shell Laying Hen and breeding variety Bailaihang chicken were used as parents, F1 generation was obtained by forward and reverse crossing, and then F2 generation was bred by using F1 as parents. Pedigree information was recorded. The test chickens were individually numbered with wing tags and were raised in single cages in a fully enclosed chicken house. Artificial light was provided for 16 hours during the laying period, and air conditioning and wet curtains were used for cooling. Routine immunization was carried out according to the immunization program formulated by Jiangsu Poultry Research Institute. The feed came from COFCO Corporation, and the components of the laying hen feed included 16.5% crude protein and 11511 kJ / kg feed metabolizable energy. The laying hens were allowed to freely eat and drink, and the feed was supplied by a line car feeder and the manure was cleaned by a chicken manure conveyor belt. The first egg laying weight was determined according to the industry standard of the Ministry of Agriculture and Rural Affairs of the People's Republic of China.

[0052] After preliminary screening of the first egg laying weight data, removing obviously incorrect and repeated data, removing outliers, and arranging into an excel table form, after data cleaning, the resource population F2 generation first egg laying weight data set remained 1512 records, which were used for the next GWAS analysis and to analyze the genetic structure.

[0053] Example 2

[0054] GWAS analysis of first egg laying weight

[0055] The test chickens came from the F2 generation adult hens of the laying hen resource population constructed in Example 1. Blood samples of about 0.5 ml were collected from the wing veins of the test chickens and placed into BD anticoagulant tubes (Suzhou Biodot Medical Instrument Co., Ltd.), and stored at -70℃. Genomic DNA was extracted, and after 0.8% agarose electrophoresis detection and ultraviolet spectrophotometric detection, the DNA samples were diluted to 50±5 ng / μl for gene chip typing.

[0056] Using the Affymetrix gene chip 600K Chicken Genotyping Array was used for genotyping. The data quality control was performed according to the chip instruction, mainly including: quality control before typing by APT software; quality control by PLINK, removing SNP markers with detection rate lower than 0.97, removing SNP markers deviating from Hardy-Weinberg equilibrium; screening SNP by metrics.R, SNP_filter.R and SNP, CR, FLD information analysis; genotype filling by BEAGLE. After quality control, 435867 autosomal SNPs were used for subsequent analysis.

[0057] Before whole genome association analysis, multi-dimensional principal component analysis was performed to eliminate false positives and population structure. The first 5 principal components were added to the genetic model as covariate parameters, and the chicken house effect was placed in the model as a fixed effect. The independent test estimate of each SNP site was calculated by the R script "simpleM" method, and 59308 independent markers were obtained. Using multiple correction, the genome significant threshold was 8.43x10 -7 , and the genome recommended threshold was 1.69x10 -5 . The mixed linear model was used to analyze egg weight, and the significance test P value of each SNP marker was obtained. The matrix expression of the linear model is,

[0058] y = W a + x b + G u + e, wherein y represents the sample phenotype value vector; W represents the covariance matrix; a is the intercept vector; x is the genotype vector of the marker, b is the effect value of the marker; G is the genetic relationship matrix based on the chip, u is the random effect vector (here, the breeding value); and e is the residual.

[0059] After GWAS screening, bw1egg_1 (Table 1) associated with egg weight was obtained. Whole genome association analysis was performed on the egg weight of 1512 chickens, and the results are shown in Figure 1 、 Figure 2 . As shown in Figure 1 (Manhattan plot), there is a genome significant level marker on chicken chromosome 4, and there are 17 SNPs around it that exceed the genome significant level and 29 SNPs that exceed the genome recommended level, which can be used as evidence to support bw1egg_1. The QQ plot further verifies that the GWAS result is reliable. As shown in Figure 2 (QQ plot), most of the SNPs that do not deviate from the diagonal are affected by genetic drift, and the SNPs located in the tail of the QQ plot are affected by artificial selection. The inflation coefficient is calculated to be 0.949. The pedigree genetic relationship matrix is used to analyze the genetic parameters, and the heritability of egg weight is obtained to be 0.686±0.038, wherein the genetic marker bw1egg_1 can explain 4.9% of the phenotype variance, and the genetic marker bw1egg_2 can explain 3.2% of the phenotype variance.

[0060] Table 1 Genetic markers associated with egg weight

[0061]

[0062] Wherein: the marker chromosome physical position reference chicken whole genome (bGalGal1.mat.broiler.GRCg7b).

[0063] Example 3

[0064] Detection and verification of genetic marker bw1egg_1

[0065] The SNP genetic marker is used for candidate gene association analysis of Dongxiang green shell egg chicken- Bailaihang chicken resource population. The specific operation steps are as follows:

[0066] 1) PCR primer: download DNA template sequence information from NCBI website, design PCR amplification primer with primer premier 6.0 software, and the primer information is shown in table 2. PCR primer is synthesized by shanghai shenguo biological engineering co., LTD.

[0067] Table 2 amplification primer for detecting chicken egg weight genetic marker bw1egg_1

[0068]

[0069]

[0070] 2) Genomic DNA extraction: the genomic DNA of 1512 blood samples was extracted by phenol chloroform method, and after detection by ultraviolet spectrophotometer and agarose electrophoresis, PCR amplification was carried out.

[0071] 3) PCR amplification process:

[0072] ① Reaction system: 10 μl system includes 50 ng of identification material DNA template, 10 ng of forward and reverse primers, 5 μl of 2 × power Taq MasterMix, and the rest volume is supplemented with ultrapure water.

[0073] ② Reaction program: first 94℃ denaturation for 30s, 50.5℃ annealing for 30s, 72℃ extension for 30s, a total of 5 cycles; then 94℃ denaturation for 30s, 50.5℃ annealing for 30s, 72℃ extension for 30s, a total of 30 cycles; 72℃ extension for 5min, 4℃ preservation.

[0074] 4) The amplification product is sent to a sequencing company for sequence polymorphism detection.

[0075] The sequence of the amplification fragment is as follows:

[0076] >bw1egg_1

[0077]

[0078] In the sequence, [] indicates mutation sites, parentheses indicate allele variations, and bolding or underlining at the beginning and end of the sequence indicates primer sequences.

[0079] 5) Association analysis: All subjects had genotypes and initial birth weights, and then significance tests were performed. The results are as follows: Figure 3 As shown, the average starting weight of laying hens was 1160.20±118.67g for individuals with the GG genotype, 1200.78±129.45g for individuals with the TG genotype, and 1235.28±131.58g for individuals with the TT genotype. One-way ANOVA showed significant differences in starting weight among the three genotypes (P<0.01). Increasing the frequency of the G allele through genotyping technology can significantly improve the starting weight of laying hens; increasing the frequency of the GG genotype can further improve the uniformity of starting weight.

[0080] Example 4

[0081] Detection and validation of the genetic marker bw1egg_2

[0082] Candidate gene association analysis was performed on the Dongxiang Green-shelled Egg Chicken-Leihun Chicken resource population using the aforementioned SNP genetic markers. The specific steps are as follows:

[0083] 1) PCR primers: DNA template sequence information was downloaded from the NCBI website, and PCR amplification primers were designed using Primer Premier 6.0 software. Primer information is shown in Table 3. PCR primers were synthesized by Sangon Biotech (Shanghai) Co., Ltd.

[0084] Table 3. Amplification primers used to detect the genetic marker bw1egg_2 for chicken laying weight.

[0085]

[0086] 2) Genomic DNA extraction: Genomic DNA was extracted from 1512 blood samples using the phenol-formaldehyde method. After passing the tests by ultraviolet spectrophotometer and agarose electrophoresis, PCR amplification was performed.

[0087] 3) PCR amplification process:

[0088] ① Reaction system: The 10μl system includes 50ng of DNA template for identification, 10ng each of forward and reverse primers, 5μL of 2×power Taq MasterMix, and the remaining volume is made up with ultrapure water.

[0089] (ii) Reaction procedure: first 94°C denaturation for 30 s, 51.4°C annealing for 30 s, 72°C extension for 30 s, for 5 cycles; then 94°C denaturation for 30 s, 51.4°C annealing for 30 s, 72°C extension for 30 s, for 30 cycles; 72°C extension for 5 min, 4°C storage.

[0090] 4) The amplified product was sent to a sequencing company for sequence polymorphism detection.

[0091] The sequence of the amplified fragment is as follows:

[0092] >bw1egg_2

[0093]

[0094] In the sequence, the mutation site is marked with [], the allele variation is in the parentheses, and the primer sequence is shown in bold and underlined at the beginning and end of the sequence.

[0095] 5) Association analysis: the test individuals all have genotypes and open production weight, and then significance test is performed. The results show that the open production weight of the individuals with CC genotype is 1186.28±128.22 g, the open production weight of the individuals with CT genotype is 1150.45±112.65 g, and the open production weight of the individuals with TT genotype is 1165.13±110.51 g. Single factor variance analysis shows that the open production weights corresponding to the three genotypes are significantly different. Through genotyping technology, the C allele frequency can be improved, and the open production weight of laying hens can be significantly improved.

[0096] Finally, it should be noted that the terms "comprising", "including", or any other variant thereof are intended to cover non-exclusive inclusion, so that processes, methods, articles, or equipment including a series of elements not only include those elements, but also include other elements not explicitly listed, or inherent to such processes, methods, articles, or equipment.

[0097] Although the preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to these embodiments once they have the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0098] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. Use of a reagent for detecting a SNP genetic marker that affects the body weight at first egg of a chicken in the genetic breeding of layers, characterized in that, The SNP genetic marker affecting the body weight at first egg of the chicken is bw1egg_1 and / or bw1egg_2; The Ensembl number of the bw1egg_1 is rs318020581, which corresponds to the 76311052th position of the positive strand of chromosome 4 in the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 3rd intron of the gene C1QTNF7, and the base at this position is T or G; The Ensembl number of the bw1egg_2 is rs313708699, which corresponds to the 74731889th position of the positive strand of chromosome 4 in the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 8th intron of the gene SLIT2, and the base at this position is T or C; The chicken breed is Dongxiang Green Shell Laying Chicken and / or Bailaihang Chicken; The genetic breeding of the chicken is the genetic breeding of the chicken on the body weight at first egg trait; The body weight at first egg of the individual with TT genotype of the bw1egg_1 is higher than that of the individual with TG genotype, and the body weight at first egg of the individual with TG genotype is higher than that of the individual with GG genotype; The body weight at first egg of the individual with CC genotype of the bw1egg_2 is higher than that of the individual with TT and CT genotypes.

2. Use according to claim 1, characterized in that, The reagent for detecting the SNP genetic marker affecting the body weight at first egg of the chicken comprises primers for detecting the bw1egg_1 and / or the bw1egg_2, wherein the primers for detecting the bw1egg_1 comprise Primer_asm1 f and Primer_asm1 r, and the primers for detecting the bw1egg_2 comprise Primer_asm2 f and Primer_asm2 r; The nucleotide sequence of the Primer_asm1 f is shown in SEQ ID NO. 1, the nucleotide sequence of the Primer_asm1 r is shown in SEQ ID NO. 2, the nucleotide sequence of the Primer_asm2 f is shown in SEQ ID NO. 3, and the nucleotide sequence of the Primer_asm2 r is shown in SEQ ID NO.

4.

3. A method for early selection of a chicken onset of lay body weight trait, characterized by, The early selection method comprises early selection of the chicken on the body weight at first egg trait based on the genotype of the SNP genetic marker bw1egg_1 and / or bw1egg_2; The Ensembl number of the bw1egg_1 is rs318020581, which corresponds to the 76311052th position of the positive strand of chromosome 4 in the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 3rd intron of the gene C1QTNF7, and the base at this position is T or G; The Ensembl number of the bw1egg_2 is rs313708699, which corresponds to the 74731889th position of the positive strand of chromosome 4 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 8th intron of the gene SLIT2 gene, and the base here is T or C; The chicken breed is Dongxiang green-shelled egg chicken and / or white lai-hang chicken; The initial production body weight of the individual with the TT genotype of the bw1egg_1 is higher than that of the individual with the TG genotype, and the initial production body weight of the individual with the TG genotype is higher than that of the individual with the GG genotype; The initial production body weight of the individual with the CC genotype of the bw1egg_2 is higher than that of the individual with the TT and CT genotypes.

4. The method of early selection for chicken body weight traits at onset of lay according to claim 3, wherein The early selection method specifically comprises: detecting the genotype of the SNP genetic marker bw1egg_1 and / or bw1egg_2 of the to-be-tested chicken; early selecting the initial production body weight trait of the to-be-tested chicken based on the genotype of the bw1egg_1 and / or the bw1egg_2.

5. The method for early selection of chicken body weight traits at onset of lay according to claim 4, wherein The detection of the genotype of the SNP genetic marker bw1egg_1 and / or bw1egg_2 of the to-be-tested chicken specifically comprises: The detection of the genotype of the SNP genetic marker bw1egg_1 and / or bw1egg_2 of the to-be-tested chicken specifically comprises: PCR amplification is performed on the genomic DNA of the to-be-tested chicken by using Primer_asm1 f and Primer_asm1 r as primers; sequencing is performed on the PCR amplification product to obtain the genotype of the 76311052th position of the positive strand of chromosome 4 of the to-be-tested chicken; The detection of the genotype of the SNP genetic marker bw1egg_2 of the to-be-tested chicken specifically comprises: PCR amplification is performed on the genomic DNA of the to-be-tested chicken by using Primer_asm2 f and Primer_asm2 r as primers; sequencing is performed on the PCR amplification product to obtain the genotype of the 74731889th position of the positive strand of chromosome 4 of the to-be-tested chicken; The nucleotide sequence of the Primer_asm1 f is shown in SEQ ID NO. 1, and the nucleotide sequence of the Primer_asm1 r is shown in SEQ ID NO. 2; the nucleotide sequence of the Primer_asm2 f is shown in SEQ ID NO. 3, and the nucleotide sequence of the Primer_asm2 r is shown in SEQ ID NO.

4.

6. Use of a kit for detecting a SNP genetic marker affecting the onset of lay body weight in a chicken for genetic breeding of a chicken, characterized in that, The kit comprises primers for detecting bw1egg_1 and / or bw1egg_2; The Ensembl number of the bw1egg_1 is rs318020581, which corresponds to the 76311052th position of the positive strand of chromosome 4 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 3rd intron of the gene C1QTNF7, and the base here is T or G; The Ensembl number of the bw1egg_2 is rs313708699, which corresponds to the 74731889th position of the positive strand of chromosome 4 in the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI, belongs to the 8th intron of the SLIT2 gene, and the base here is T or C; The primer for detecting the bw1egg_1 includes Primer_asm1 f and Primer_asm1 r, and the primer for detecting the bw1egg_2 includes Primer_asm2f and Primer_asm2r; The nucleotide sequence of the Primer_asm1 f is shown in SEQ ID NO. 1, the nucleotide sequence of the Primer_asm1 r is shown in SEQ ID NO. 2, the nucleotide sequence of the Primer_asm2f is shown in SEQ ID NO. 3, and the nucleotide sequence of the Primer_asm2r is shown in SEQ ID NO. 4; The chicken breed is Dongxiang green shell laying hen and / or Bailaihang chicken; The chicken genetic breeding is the genetic breeding of the chicken on the laying weight trait; The laying weight of the TT genotype individual of the bw1egg_1 is higher than that of the TG genotype individual, and the laying weight of the TG genotype individual is higher than that of the GG genotype individual; The laying weight of the CC genotype individual of the bw1egg_2 is higher than that of the TT and CT genotype individuals.

7. Use of a reagent for detecting a SNP genetic marker that affects the onset body weight in chickens in the prediction of the onset body weight in chickens, characterized in that, The SNP genetic marker affecting the laying weight of the chicken is bw1egg_1 and / or bw1egg_2; The Ensembl number of the bw1egg_1 is rs318020581, which corresponds to the 76311052th position of the positive strand of chromosome 4 in the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI, belongs to the 3rd intron of the C1QTNF7 gene, and the base here is T or G; The Ensembl number of the bw1egg_2 is rs313708699, which corresponds to the 74731889th position of the positive strand of chromosome 4 in the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI, belongs to the 8th intron of the SLIT2 gene, and the base here is T or C; The chicken breed is Dongxiang green shell laying hen and / or Bailaihang chicken; The laying weight of the TT genotype individual of the bw1egg_1 is higher than that of the TG genotype individual, and the laying weight of the TG genotype individual is higher than that of the GG genotype individual; The laying weight of the CC genotype individual of the bw1egg_2 is higher than that of the TT and CT genotype individuals.

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