Application of SNP (Single Nucleotide Polymorphism) genetic marker influencing laying weight in genetic breeding of laying hens

Abstract

The invention provides application of an SNP (Single Nucleotide Polymorphism) genetic marker influencing the laying weight of chickens in genetic breeding of laying hens, and belongs to the technical field of animal genetic breeding and biology. The SNP genetic marker influencing the laying weight of the chickens comprises bw1egg1 and / or bw1egg2; the Ensemb l number of the bw1egg1 is rs318020581, corresponds to the 76311052nd site of a positive-sense strand of a chromosome 4 of a chicken reference genome bGa < 1 > Ga < 1. Mat.broi ler.GRCg7b sequence published in NCBI (National Center of Biotechnology Information) and belongs to the third intron of a gene C1QTNF7, and a basic group in the site is T or G; the Ensemb l of the bw1egg2 is numbered as rs313708699, corresponds to the 74731889 site of a positive-sense strand of a chromosome 4 of a chicken reference genome bGa < 1 > Ga < 1. Mat.broi ler.GRCg7b sequence disclosed in NCBI (National Center of Biotechnology Information), and belongs to the eighth intron of a T2 gene of a gene SLI, and a basic group is T or C at the position. The bw1egg1 and the bw1egg2 are both beneficial to heredity improvement of the first laying weight, the bw1egg1 and the bw1egg2 are applied to genetic breeding of chickens, improvement of the first laying weight of laying hens is facilitated, and a laying hen variety with excellent first laying weight uniformity is obtained.

Description

Technical Field

[0001] The invention belongs to the field of animal genetic breeding and biotechnology, and particularly relates to the application of a SNP genetic marker affecting the initial laying weight of a chicken in the genetic breeding of laying hens. Background Art

[0002] The weight at the beginning of laying is a commonly used indicator for breeding of laying hens. It can be used to identify whether laying hens are sexually mature, measure the uniformity of the group, and predict egg-laying performance. Studies have shown that there is a clear lower limit for poultry weight, and hens below the threshold cannot reach sexual maturity. The beginning of laying in chickens is a complex physiological development process, which is not only regulated by external environmental factors, such as the duration of light, but also affected by genetic factors. Generally speaking, only by genetically changing the frequency of related genes can lasting and cumulative progress be achieved. In recent years, the GWAS method has been extended to the analysis of the genetic structure of quantitative traits in laying hens, mainly used for the study of egg production, feed utilization efficiency, and egg quality. It is rare to use the GWAS method to analyze the genetic structure of laying hens' weight at the beginning of laying. In recent years, the GWAS method has been extended to the analysis of the genetic structure of quantitative traits in laying hens, mainly used for the study of egg production, feed utilization efficiency, and egg quality. It is rare to use the GWAS method to analyze the genetic structure of laying hens' weight at the beginning of laying. The trait of weight at birth is regulated by micro-effect multiple genes. Conventional breeding methods are difficult to make effective progress genetically. The only way to genetically influence weight at birth is to clarify the genetic structure of weight at birth.

[0003] Dongxiang green-shell laying hens are native to Dongxiang County, Jiangxi Province and nearby areas. They are a famous local chicken breed for laying eggs in my country and a national geographical indication variety. Dongxiang green-shell laying hens are named for their green-shell eggs. They have a long history of breeding in rural areas and have many traits. Their feathers are black, white, yellow, and hemp. Their skin color is black or white, and their ear lobes are yellow, white, and purple. After selection and breeding, Dongxiang green-shell laying hens can be used to build the supporting system of Suqin green-shell laying hens and Shendan No. 6 green-shell laying hens, occupying an important position in the laying hen market. Systematic research on the genetic structure of the weight of Dongxiang green-shell laying hens at the beginning of production is of great significance for the development and utilization of Dongxiang green-shell laying hens. The weight at the beginning of production is a late trait of the life body and can only be measured at the beginning of production, which leads to an increase in the feeding cost of breeding and screening. Therefore, it is urgent to find suitable molecular markers to achieve early selection through genetic marker-assisted breeding or genomic selection, so as to quickly obtain the genetic progress of the weight of laying hens at the beginning of production, and then achieve the purpose of improving the uniformity of the weight of laying hens at the beginning of production.

[0004] In addition, Dongxiang green-shell laying hens have not undergone high-intensity breeding, so their production performance is poor, especially the coefficient of variation of their weight at the beginning of laying is large, which makes it difficult to meet the needs of modern laying hen production. In order to meet the demand for green-shell eggs in the egg market and to tap into the genetic resources of local chicken breeds in my country, it is urgent to find new molecular markers and enrich the genetic marker library related to the weight of laying hens, so as to genetically improve the weight of laying hens. Summary of the Invention

[0005] In order to genetically improve the body weight at the onset of lay in laying hens, the present invention provides the application of SNP genetic markers affecting the body weight at the onset of lay in chickens in the genetic breeding of laying hens. The SNP genetic markers bw1egg_1 and bw1egg_2 affecting the body weight at the onset of lay in chickens contribute to genetically improving the body weight at the onset of lay. Applying them to the genetic breeding of chickens is beneficial to improving the body weight at the onset of lay in laying hens and obtaining a laying hen breed with excellent uniformity in body weight at the onset of lay.

[0006] The present invention is achieved through the following technical solutions:

[0007] The present invention provides the application of SNP genetic markers affecting the body weight at the onset of lay in chickens in the genetic breeding of laying hens, and the SNP genetic markers affecting the body weight at the onset of lay in chickens include bw1egg_1 and / or bw1egg_2;

[0008] The Ensembl number of bw1egg_1 is rs318020581, corresponding to the 76311052nd position on the sense strand of chromosome 4 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 3rd intron of gene C1QTNF7, and the base here is T or G;

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

[0010] Based on the same inventive concept, the present invention provides an early selection method for the body weight trait at the onset of lay in chickens, and the early selection method includes early selecting the body weight trait at the onset of lay in chickens based on the genotypes of the SNP genetic markers bw1egg_1 and / or bw1egg_2;

[0011] The Ensembl number of bw1egg_1 is rs318020581, corresponding to the 76311052nd position on the sense strand of chromosome 4 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 3rd intron of gene C1QTNF7, and the base here is T or G;

[0012] The Ensembl ID of bw1egg_2 is rs313708699, corresponding to the 74,731,889th position on the plus strand of chromosome 4 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 8th intron of the gene SLIT2, where the base is T or C.

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

[0014] Detect the genotypes of the SNP genetic markers bw1egg_1 and / or bw1egg_2 in the chicken to be tested;

[0015] Based on the genotypes of bw1egg_1 and / or bw1egg_2, conduct early selection on the age at first egg weight trait of the chicken to be tested;

[0016] Among them, the age at first egg weight of individuals with the TT genotype of bw1egg_1 is higher than that of individuals with the TG genotype, and the age at first egg weight of individuals with the TG genotype is higher than that of individuals with the GG genotype;

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

[0018] Further, detecting the genotypes of the SNP genetic markers bw1egg_1 and / or bw1egg_2 in the chicken to be tested specifically includes:

[0019] Detect the genotypes of the SNP genetic markers bw1egg_1 and / or bw1egg_2 in the chicken to be tested. Among them, the method for detecting the genotype of bw1egg_1 is as follows:

[0020] Using Primer_asm1f and Primer_asm1r as primers, perform PCR amplification on the genomic DNA of the chicken to be tested;

[0021] Sequence the PCR amplification product to obtain the genotype at the 76,311,052nd position on the plus strand of chromosome 4 of the chicken to be tested;

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

[0023] Using Primer_asm2f and Primer_asm2r as primers, perform PCR amplification on the genomic DNA of the chicken to be tested;

[0024] Sequence the PCR amplification product to obtain the genotype at the 74,731,889th position on the plus strand of chromosome 4 of the chicken to be tested;

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

[0026] Furthermore, the breeds of the chickens to be tested include Dongxiang green-shell egg chickens and / or White Leghorn chickens.

[0027] Based on the same inventive concept, the present invention provides the application of reagents for detecting SNP genetic markers affecting the age at first egg weight in genetic breeding of laying hens. The SNP genetic markers affecting the age at first egg weight include bw1egg_1 and / or bw1egg_2;

[0028] The Ensembl ID of bw1egg_1 is rs318020581, corresponding to the 76,311,052nd position on the plus strand of chromosome 4 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 3rd intron of gene C1QTNF7, and the base here is T or G;

[0029] The Ensembl ID of bw1egg_2 is rs313708699, corresponding to the 74,731,889th position on the plus strand of chromosome 4 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 8th intron of gene SLIT2, and the base here is T or C.

[0030] Furthermore, the reagents for detecting SNP genetic markers affecting the age at first egg weight include primers for detecting bw1egg_1 and / or bw1egg_2. The primers for detecting bw1egg_1 include Primer_asm1f and Primer_asm1r, and the primers for detecting bw1egg_2 include Primer_asm2f and Primer_asm2r;

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

[0032] Based on the same inventive concept, the present invention provides a kit for detecting SNP genetic markers affecting the body weight at first egg in chickens. The kit contains primers for detecting bw1egg_1 and / or bw1egg_2. The primers for detecting bw1egg_1 include Primer_asm1f and Primer_asm1r, and the primers for detecting bw1egg_2 include Primer_asm2f and Primer_asm2r;

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

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

[0035] Based on the same inventive concept, the present invention also provides the application of SNP genetic markers affecting the body weight at first egg in predicting the body weight at first egg in chickens. The SNP genetic markers affecting the body weight at first egg include bw1egg_1 and / or bw1egg_2;

[0036] The Ensembl ID of bw1egg_1 is rs318020581, corresponding to the 76311052nd position on the sense strand of chromosome 4 in the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 3rd intron of gene C1QTNF7, and the base here is T or G;

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

[0038] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0039] The application of SNP genetic markers affecting the age at first egg body weight of chickens in the genetic breeding of laying hens. The SNP genetic markers affecting the age at first egg body weight of chickens include bw1egg_1 and bw1egg_2, both of which are located on chicken chromosome 4. Both bw1egg_1 and bw1egg_2 are associated with the age at first egg body weight trait of chickens, and their superior genotype populations have a higher level of age at first egg body weight. Applying bw1egg_1 and / or bw1egg_2 to the genetic breeding of chickens helps to genetically improve the age at first egg body weight level of the laying hen population, and then obtain a laying hen breed with excellent uniformity in age at first egg body weight. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0041] Figure 1 It is the Manhattan plot of the GWAS analysis of the age at first egg body weight of the resource population in Example 2 of the present invention;

[0042] Figure 2 It is the QQ plot of the GWAS analysis of the age at first egg body weight of the resource population in Example 2 of the present invention;

[0043] Figure 3 It is the box plot of the age at first egg body weight of individuals with different genotypes in Example 3 of the present invention;

[0044] Figure 4 It is the box plot of the age at first egg body weight of individuals with different genotypes in Example 4 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] The following will specifically describe the present invention in combination with the specific embodiments and examples, and the advantages and various effects of the present invention will be presented more clearly therefrom. Those skilled in the art should understand that these specific embodiments and examples are used to illustrate the present invention, rather than to limit the present invention.

[0046] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as the general understanding of those skilled in the art to which the present invention belongs. In case of contradiction, this specification shall prevail.

[0047] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through market purchases or can be prepared by existing methods.

[0048] The following will elaborate on the application of the SNP genetic markers affecting the age at first egg body weight of the present application in the genetic breeding of laying hens in combination with examples and experimental data.

[0049] Example 1

[0050] Construction of the resource population

[0051] To analyze the genetic structure of egg-related traits, a laying hen resource population was constructed according to the F2 design. Using the local chicken breed Dongxiang Green-shell Laying Hens and the selected breed White Leghorns as parents, the F1 generation was obtained through reciprocal crosses, and then the F2 generation was bred with the F1 as parents. Pedigree information was recorded. The experimental chickens were individually marked with wing tags and raised in single cages in a fully enclosed chicken house. During the laying period, artificial lighting was supplemented for 16 hours, and the temperature was reduced by fans and wet curtains. Routine immunization was carried out according to the immunization program formulated by the Jiangsu Institute of Poultry Sciences. The feed was from COFCO. The feed components for laying hens included 16.5% crude protein and 11511 kJ / kg of feed metabolic energy. During the laying period, the chickens had free access to food, were supplied with water through nipple drinkers, fed with a traveling feeder, and the chicken manure was removed by a manure conveyor belt. The age at first egg body weight was measured according to the industry standard of the Ministry of Agriculture and Rural Affairs of the People's Republic of China.

[0052] The data of the age at first egg body weight were preliminarily screened. After removing the obviously incorrect and duplicate data, the outliers were removed and organized into an excel table form. After data cleaning, the dataset of the age at first egg body weight of the F2 generation of the resource population remained 1512 records, which were used for the next GWAS analysis and to analyze its genetic structure.

[0053] Example 2

[0054] GWAS analysis of the age at first egg body weight

[0055] The experimental chickens were adult hens of the F2 generation of the laying hen resource population constructed in Example 1. About 0.5 ml of blood samples were collected from the wing veins of the experimental chickens and placed into BD anticoagulation tubes (BD Medical Devices (Suzhou) Co., Ltd.) and stored at -70 °C. Genomic DNA was extracted and detected by 0.8% agarose gel electrophoresis and ultraviolet spectrophotometry. After passing the tests, the DNA samples were diluted to 50 ± 5 ng / μl for genotyping using gene chips.

[0056] Using Affymetrix gene chips Genotyping was performed using the 600K Chicken Genotyping Array. Quality control of the data was carried out according to the chip instruction manual, mainly including: performing quality control before genotyping using the APT software; performing quality control with PLINK, removing SNPs with a detection rate lower than 0.97 and SNPs deviating from the Hardy-Weinberg equilibrium; screening SNPs using metrics.R, SNP_filter.R, and SNP, CR, and FLD information analysis; and performing genotype imputation with BEAGLE. After quality control, 435,867 autosomal SNPs remained for subsequent analysis.

[0057] Before performing the genome-wide association study (GWAS), multi-dimensional principal component analysis was first carried out to eliminate false positives and population structure. The first five principal components were used as covariate parameters and added to the genetic model, and the chicken house effect was placed in the fixed effect of the model. The "simpleM" method in the R script was used to calculate the independent test estimates of each SNPs locus, and 59,308 independent markers were obtained. Using multiple corrections, the genome-wide significant threshold was obtained as 8.43×10 -7 , and the genome-wide suggestive threshold was 1.69×10 -5 . The mixed linear model was used to analyze the body weight at first egg, and the P-values of the significance test for each SNPs marker were obtained. The matrix expression of the linear model is,

[0058] y = Wα + xβ + Gu + ε where y represents the vector of sample phenotypic values; W represents the covariance matrix; α is the intercept vector; x is the genotype vector of the marker, and β is the effect value of the marker; G is the genetic relationship matrix constructed based on the chip, u is the random effect vector (here it is the breeding value); and ε is the residual.

[0059] After screening by GWAS, bw1egg_1 associated with the body weight at first egg was obtained (Table 1). Genome-wide association analysis was performed on the body weight at first egg of 1,512 chickens, and the results are as Figure 1 、 Figure 2 shown. As can be seen from Figure 1 (Manhattan plot), there are markers at the genome-wide significant level on chicken chromosome 4, and there are 17 SNPs around it exceeding the genome-wide significant level and 29 SNPs exceeding the genome-wide suggestive level, which can be used as evidence to support bw1egg_1. The QQ plot further verified the reliability of the GWAS results. As can be seen from Figure 2 (QQ plot), the vast majority of SNPs that do not deviate from the diagonal line are affected by genetic drift, and the SNPs at the tail of the QQ plot are affected by artificial selection. The inflation coefficient was calculated to be 0.949. The genetic parameters were analyzed using the pedigree genetic relationship matrix, and the heritability of the body weight at first egg was obtained as 0.686 ± 0.038. Among them, the bw1egg_1 genetic marker can explain 4.9% of the phenotypic variance, and the bw1egg_2 genetic marker can explain 3.2% of the phenotypic variance.

[0060] Table 1 Genetic markers related to the body weight at first egg

[0061]

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

[0063] Example 3

[0064] Detection and verification of the genetic marker bw1egg_1

[0065] Perform candidate gene association analysis on the Dongxiang green-shelled egg chicken - White Leghorn chicken resource population using the above SNP genetic markers. The specific operation steps are as follows:

[0066] 1) PCR primers: Download the DNA template sequence information from the NCBI website, and design PCR amplification primers using the primer premier 6.0 software. The primer information is shown in Table 2. The PCR primers are synthesized by Sangon Biotech (Shanghai) Co., Ltd.

[0067] Table 2 Amplification primers used to detect the genetic marker bw1egg_1 of the body weight at first egg in chickens

[0068]

[0069]

[0070] 2) Genomic DNA extraction: Extract genomic DNA from 1512 blood samples by the phenol-chloroform method. After being qualified by ultraviolet spectrophotometer detection and agarose gel electrophoresis detection, perform PCR amplification.

[0071] 3) PCR amplification process:

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

[0073] ② Reaction program: First, denature at 94°C for 30 s, anneal at 50.5°C for 30 s, and extend at 72°C for 30 s, for a total of 5 cycles; then denature at 94°C for 30 s, anneal at 50.5°C for 30 s, and extend at 72°C for 30 s, for a total of 30 cycles; extend at 72°C for 5 min and store at 4°C.

[0074] 4) Send the amplification product to a sequencing company for sequence polymorphism detection.

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

[0076] >bw1egg_1

[0077]

[0078] In the sequence, the sites marked with [] are mutation sites, and the allelic variations are in parentheses. The primer sequences are shown in bold and underlined at the beginning and end of the sequence.

[0079] 5) Association analysis: All the tested individuals had genotypes and body weights at first laying. Then, significance tests were performed. The results are as Figure 3 shown. The body weight at first laying of individuals with the GG genotype was 1160.20 ± 118.67 g, that of individuals with the TG genotype was 1200.78 ± 129.45 g, and that of individuals with the TT genotype was 1235.28 ± 131.58 g. One-way ANOVA showed that there were significant differences in the body weights at first laying corresponding to the three genotypes (P < 0.01). By using genotyping technology to increase the frequency of the G allele, the body weight at first laying of laying hens can be significantly improved; by increasing the frequency of the GG genotype, the uniformity of the body weight at first laying of laying hens can be further improved.

[0080] Example 4

[0081] Detection and verification of genetic marker bw1egg_2

[0082] The above SNP genetic marker was used for candidate gene association analysis in the Dongxiang green-shell layer - White Leghorn resource population. The specific operation steps are as follows:

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

[0084] Table 3 Amplification primers for detecting the genetic marker bw1egg_2 of chicken body weight at first laying

[0085]

[0086] 2) Genomic DNA extraction: Genomic DNA of 1512 blood samples was extracted by the phenol-chloroform method. After being qualified by ultraviolet spectrophotometer detection and agarose gel electrophoresis detection, PCR amplification was carried out.

[0087] 3) PCR amplification process:

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

[0089] ② Reaction procedure: First, denature at 94°C for 30 s, anneal at 51.4°C for 30 s, extend at 72°C for 30 s, for a total of 5 cycles; then denature at 94°C for 30 s, anneal at 51.4°C for 30 s, extend at 72 °C for 30 s, for a total of 30 cycles; extend at 72°C for 5 min and store at 4°C.

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

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

[0092] >bw1egg_2

[0093]

[0094] In the sequence, the sites marked with [] are mutation sites, and the allelic variations are in parentheses. The primer sequences are shown in bold and underlined at the beginning and end of the sequence.

[0095] 5) Association analysis: All the subjects had genotypes and body weights at the onset of laying, and then a significance test was conducted. The results showed that the body weights at the onset of laying of individuals with the CC genotype were 1186.28 ± 128.22 g, those with the CT genotype were 1150.45 ± 112.65 g, and those with the TT genotype were 1165.13 ± 110.51 g. One-way ANOVA showed that there were significant differences in the body weights at the onset of laying corresponding to the three genotypes. By using genotyping technology to increase the frequency of the C allele, the body weights at the onset of laying of laying hens can be significantly improved.

[0096] Finally, it should also be noted that the term "comprises", "comprising" or any other variation thereof is intended to cover a non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device.

[0097] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

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

Claims

1. Application of SNP genetic markers affecting the initial laying weight of chickens in laying hen genetic breeding, characterized in that: The SNP genetic markers affecting the chicken's initial laying weight include bw1egg_1 and / or bw1egg_2; The Ensembl number of bw1egg_1 is rs318020581, corresponding 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 third intron of gene C1QTNF7, where the base 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 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 8th intron of the SLIT2 gene, where the base is T or C.

2. A method for early selection of chicken weight traits at the beginning of laying hens, characterized in that: The early selection method comprises performing early selection on the chicken laying weight trait based on the genotype of the SNP genetic marker bw1egg_1 and / or bw1egg_2; The Ensembl number of bw1egg_1 is rs318020581, corresponding 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 third intron of gene C1QTNF7, where the base 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 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 8th intron of the SLIT2 gene, where the base is T or C.

3. The method for early selection of chicken weight traits at the beginning of laying hens according to claim 2, characterized in that: The early selection method specifically includes: Detecting the genotype of the chicken SNP genetic marker bw1egg_1 and / or bw1egg_2 to be tested; Performing early selection on the genotype of the chicken to be tested for the weight trait of the first laying hens based on the genotype of the bw1egg_1 and / or the bw1egg_2; Among them, the first-time calving weight of individuals with TT genotype of bw1egg_1 is higher than that of individuals with TG genotype, and the first-time calving weight of individuals with TG genotype is higher than that of individuals with GG genotype; The initial calving weight of the CC genotype individuals of the bw1egg_2 was higher than that of the TT and CT genotype individuals.

4. The method for early selection of chicken weight traits at the beginning of laying hens according to claim 3, characterized in that: The detecting of the genotype of the chicken SNP genetic marker bw1egg_1 and / or bw1egg_2 specifically comprises: Detect the genotype of the chicken SNP genetic marker bw1egg_1 and / or bw1egg_2 to be tested, wherein the method for detecting the bw1egg_1 genotype is as follows: The genomic DNA of the chicken to be tested was amplified by PCR using Primer_asm1 f and Primer_asm1 r; The PCR amplification product was sequenced to obtain the genotype of position 76311052 of the positive strand of the tested chicken chromosome 4; The method for detecting the bwlegg_2 genotype is as follows: Using Primer_asm2f and Primer_asm2r as primers, PCR amplification was performed on the genomic DNA of the tested chicken; The PCR amplification product was sequenced to obtain the genotype of position 74731889 of the positive strand of the tested chicken chromosome 4; Among them, the nucleotide sequence of Primer_asm1 f is shown as SEQ ID NO.1, and the nucleotide sequence of Primer_asm1 r is shown as SEQ ID NO.2; the nucleotide sequence of Primer_asm2f is shown as SEQ ID NO.3, and the nucleotide sequence of Primer_asm2r is shown as SEQ ID NO.

4.

5. The early selection method for the weight trait of chickens at the beginning of laying hens according to claim 3 or 4, characterized in that: The breeds of chickens to be tested include Dongxiang green-shell laying hens and / or white Leghorn chickens.

6. Application of a reagent for detecting SNP genetic markers affecting the initial laying weight of chickens in laying hen genetic breeding, characterized in that: The SNP genetic markers affecting the chicken's initial laying weight include bw1egg_1 and / or bw1egg_2; The Ensembl number of bw1egg_1 is rs318020581, corresponding 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 third intron of gene C1QTNF7, where the base 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 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 8th intron of the SLIT2 gene, where the base is T or C.

7. The use according to claim 6, characterized in that: The reagent for detecting the SNP genetic marker affecting the weight of chickens at the beginning of laying, comprises primers for detecting bw1egg_1 and / or bw1egg_2, wherein the primers for detecting bw1egg_1 comprise Primer_asm1 f and Primer_asm1 r, and the primers for detecting bw1egg_2 comprise Primer_asm2f and Primer_asm2r; The nucleotide sequence of Primer_asm1 f is shown in SEQ ID NO.1, and the nucleotide sequence of Primer_asm1 r is shown in SEQ ID NO.2; the nucleotide sequence of Primer_asm2f is shown in SEQ ID NO.3, and the nucleotide sequence of Primer_asm2r is shown in SEQ ID NO.

4.

8. A kit for detecting SNP genetic markers that affect the weight of chickens at the beginning of laying, characterized in that: The kit comprises primers for detecting bw1egg_1 and / or bw1egg_2, wherein the primers for detecting bw1egg_1 include Primer_asm1 f and Primer_asm1 r, and the primers for detecting bw1egg_2 include Primer_asm2f and Primer_asm2r; The nucleotide sequence of Primer_asm1 f is shown in SEQ ID NO.1, and the nucleotide sequence of Primer_asm1 r is shown in SEQ ID NO.2; the nucleotide sequence of Primer_asm2f is shown in SEQ ID NO.3, and the nucleotide sequence of Primer_asm2r is shown in SEQ ID NO.

4.

9. Use of the kit as claimed in claim 8 in chicken genetic breeding.

10. Application of SNP genetic markers affecting the first-laying weight of chickens in predicting the first-laying weight of chickens, characterized in that: The SNP genetic markers affecting the chicken's initial laying weight include bw1egg_1 and / or bw1egg_2; The Ensembl number of bw1egg_1 is rs318020581, corresponding 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 third intron of gene C1QTNF7, where the base 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 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI, belonging to the 8th intron of the SLIT2 gene, where the base is T or C.

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