Application of SNP molecular marker affecting age at first egg in layer breeding

Abstract

The application provides application of SNP molecular markers affecting the age of first egg laying of chickens in the breeding of laying hens, belongs to the field of animal genetics and breeding and biotechnology, and the SNP molecular markers affecting the age of first egg laying of chickens include AFE_chr16_1 and / or AFE_chr16_2; the Ensembl number of the AFE_chr16_1 is rs316781747, corresponds to the 2078538th position of the positive strand of the 16th chromosome of the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI, belongs to the 1st intron of the gene TRIM7.2, and the base at the position is G or C; the Ensembl number of the AFE_chr16_2 is rs15788024, corresponds to the 2121574th position of the positive strand of the 16th chromosome of the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI, belongs to the 4th intron of the gene TRIM39.2, and the base at the position is T or C. Both AFE_chr16_1 and AFE_chr16_2 are helpful to genetically make the age of first egg laying of laying hens earlier, and the application of the two in the genetic breeding of chickens is beneficial to shortening the age of first egg laying of laying hens and meeting the demand of the egg market for green-shell egg chicken varieties.

Description

Technical Field

[0001] This invention belongs to the fields of animal genetics and breeding and biotechnology, and specifically relates to the application of SNP molecular markers that affect the age of laying hens in egg-laying hen breeding. Background Technology

[0002] Age at onset of egg production is a commonly used indicator in laying hen breeding. It can be used to determine whether hens are sexually mature, measure flock evenness, and predict egg production performance. Studies have shown that there is a clear lower limit to the age at onset of egg production in poultry; hens below this threshold cannot reach sexual maturity. The onset of egg production in chickens is a complex physiological developmental process, regulated not only by external environmental factors, such as photoperiod, but also by genetic factors. Generally, only by genetically altering the frequencies of relevant genes can lasting, cumulative progress be achieved. In recent years, GWAS methods have been extended to the analysis of the genetic structure of quantitative traits in laying hens, mainly used for studies on egg production, feed utilization efficiency, and egg quality. However, GWAS analysis of the genetic structure of age at onset of egg production is less common. The age at onset trait is regulated by multiple genes with minor effects, and conventional breeding methods are insufficient to achieve effective genetic progress. Only by clarifying the genetic structure of age at onset can we genetically influence it.

[0003] The Dongxiang Green-Shelled Chicken, originating from the area near Dongxiang County, Jiangxi Province, is a well-known local egg-laying chicken breed in my country and a national geographical indication breed. Named for its green-shelled eggs, the Dongxiang Green-Shelled Chicken, after selective breeding, is used to construct the Suqin Green-Shelled Chicken and Shendan No. 6 Green-Shelled Chicken breeding lines, holding an important position in the egg-laying chicken market. A systematic study of the genetic structure of the age at first egg production in the Dongxiang Green-Shelled Chicken is of great significance for its development and utilization. Age at first egg production is a late-life trait, measurable only at the onset of laying, leading to increased feeding costs associated with genetic selection. Therefore, it is urgent to find suitable molecular markers to achieve early selection through marker-assisted breeding or genomic selection, rapidly improving the age at first egg production in laying hens.

[0004] Because Dongxiang green-shelled chickens have not undergone intensive selective breeding, their production performance is poor, especially in terms of late onset of egg production and poor uniformity, making it difficult to meet the needs of modern egg production. To meet the market demand for green-shelled eggs and to explore the genetic resources of local chicken breeds in my country, it is urgent to find new molecular markers to enrich the genetic marker library related to the age at which chickens begin laying, thereby genetically shortening the age at which laying hens begin laying. Summary of the Invention

[0005] To genetically shorten the age at which laying hens begin laying, this invention provides the application of SNP molecular markers that affect the age at which chickens begin laying in laying hen breeding. The SNP molecular markers that affect the age at which chickens begin laying include AFE_chr16_1 and AFE_chr16_2. Both AFE_chr16_1 and AFE_chr16_2 can help to genetically advance the age at which laying hens begin laying. Applying them to chicken genetic breeding is beneficial for shortening the age at which laying hens begin laying.

[0006] This invention is achieved through the following technical solution:

[0007] This invention provides the application of SNP molecular markers that affect the age of laying in chickens in layer hen breeding, wherein the SNP molecular markers that affect the age of laying in chickens include AFE_chr16_1 and / or AFE_chr16_2;

[0008] The Ensembl number of AFE_chr16_1 is rs316781747, which corresponds to position 2078538 on the positive strand of chromosome 16 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI. It belongs to the first intron of the gene TRIM7.2, where the base is G or C.

[0009] The Ensembl number of AFE_chr16_2 is rs15788024, which corresponds to position 2121574 on the positive strand of chromosome 16 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI. It belongs to the 4th intron of the gene TRIM39.2, where the base is T or C.

[0010] Based on the same inventive concept, the present invention provides an early selection method for the age at first laying trait in chickens, the early selection method comprising early selection of the age at first laying trait in chickens based on the genotypes of SNP molecular markers AFE_chr16_1 and / or AFE_chr16_2;

[0011] The Ensembl number of AFE_chr16_1 is rs316781747, which corresponds to position 2078538 on the positive strand of chromosome 16 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI. It belongs to the first intron of the gene TRIM7.2, where the base is G or C.

[0012] The Ensembl number of AFE_chr16_2 is rs15788024, which corresponds to position 2121574 on the positive strand of chromosome 16 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI. It belongs to the 4th intron of the gene TRIM39.2, where the base is T or C.

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

[0014] Detect the genotypes of the SNP molecular markers AFE_chr16_1 and / or AFE_chr16_2 in the test chickens;

[0015] Early selection of the age at first laying trait in the target chickens based on the genotypes of AFE_chr16_1 and / or AFE_chr16_2;

[0016] Among them, the age at onset of labor of individuals with the CC genotype of AFE_chr16_1 is earlier than that of individuals with the GC and GG genotypes;

[0017] The TT genotype individuals of the AFE_chr16_2 strain had an earlier age of onset than the TC and CC genotype individuals.

[0018] Furthermore, the detection of the genotypes of the chicken SNP molecular markers AFE_chr16_1 and / or AFE_chr16_2 specifically includes:

[0019] The genotypes of the SNP molecular markers AFE_chr16_1 and / or AFE_chr16_2 in the target chicken were detected. The method for detecting the AFE_chr16_1 genotype is as follows:

[0020] Using Pr_afe_16_1f and Pr_afe_16_1r as primers, PCR amplification was performed on the genomic DNA of the chickens to be tested.

[0021] The PCR amplification products were sequenced to obtain the genotype at position 2078538 on the positive strand of chromosome 16 of the chicken to be tested.

[0022] The method for detecting the AFE_chr16_2 genotype is as follows:

[0023] Using Pr_afe_16_2f and Pr_afe_16_2r as primers, PCR amplification was performed on the genomic DNA of the chickens to be tested;

[0024] The PCR amplification products were sequenced to obtain the genotype at position 2121574 on the positive strand of chromosome 16 of the chicken to be tested.

[0025] The nucleotide sequence of Pr_afe_16_1f is shown in SEQ ID NO.1, the nucleotide sequence of Pr_afe_16_1r is shown in SEQ ID NO.2, the nucleotide sequence of Pr_afe_16_2f is shown in SEQ ID NO.3, and the nucleotide sequence of Pr_afe_16_2r is shown in SEQ ID NO.4.

[0026] Furthermore, the breeds of chickens to be tested include Dongxiang Green-shelled Egg Chicken and / or White Leghorn Chicken.

[0027] Based on the same inventive concept, the present invention provides the application of a detection reagent for SNP molecular markers affecting the age of laying hens in the genetic breeding of laying hens, wherein the SNP molecular markers affecting the age of laying hens include AFE_chr16_1 and / or AFE_chr16_2.

[0028] The Ensembl number of AFE_chr16_1 is rs316781747, which corresponds to position 2078538 on the positive strand of chromosome 16 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI. It belongs to the first intron of the gene TRIM7.2, where the base is G or C.

[0029] The Ensembl number of AFE_chr16_2 is rs15788024, which corresponds to position 2121574 on the positive strand of chromosome 16 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI. It belongs to the 4th intron of the gene TRIM39.2, where the base is T or C.

[0030] Furthermore, the detection reagent for the SNP molecular markers affecting the age of first laying in chickens includes primers for detecting AFE_chr16_1 and / or AFE_chr16_2, wherein the primers for detecting AFE_chr16_1 include Pr_afe_16_1f and Pr_afe_16_1r, and the primers for detecting AFE_chr16_2 include Pr_afe_16_2f and Pr_afe_16_2r;

[0031] The nucleotide sequence of Pr_afe_16_1f is shown in SEQ ID NO.1, the nucleotide sequence of Pr_afe_16_1r is shown in SEQ ID NO.2, the nucleotide sequence of Pr_afe_16_2f is shown in SEQ ID NO.3, and the nucleotide sequence of Pr_afe_16_2r is shown in SEQ ID NO.4.

[0032] Based on the same inventive concept, the present invention provides a kit for detecting SNP molecular markers that affect the age of first laying in chickens. The kit contains primers for detecting AFE_chr16_1 and / or AFE_chr16_2. The primers for detecting AFE_chr16_1 include Pr_afe_16_1f and Pr_afe_16_1r, and the primers for detecting AFE_chr16_2 include Pr_afe_16_2f and Pr_afe_16_2r.

[0033] The nucleotide sequence of Pr_afe_16_1f is shown in SEQ ID NO.1, the nucleotide sequence of Pr_afe_16_1r is shown in SEQ ID NO.2, the nucleotide sequence of Pr_afe_16_2f is shown in SEQ ID NO.3, and the nucleotide sequence of Pr_afe_16_2r is shown in SEQ ID NO.4.

[0034] Based on the same inventive concept, this invention provides the application of a kit for detecting SNP molecular markers that affect the age of first laying in chickens in chicken genetic breeding.

[0035] Based on the same inventive concept, the present invention provides the application of SNP molecular markers that affect the age of chicken laying in predicting the age of chicken laying, wherein the SNP molecular markers that affect the age of chicken laying include AFE_chr16_1 and / or AFE_chr16_2.

[0036] The Ensembl number of AFE_chr16_1 is rs316781747, which corresponds to position 2078538 on the positive strand of chromosome 16 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI. It belongs to the first intron of the gene TRIM7.2, where the base is G or C.

[0037] The Ensembl number of AFE_chr16_2 is rs15788024, which corresponds to position 2121574 on the positive strand of chromosome 16 of the chicken reference genome bGalGal1.mat.broiler.GRCg7b sequence published in NCBI. It belongs to the 4th intron of the gene TRIM39.2, where the base 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] This invention relates to the application of SNP molecular markers affecting the age of egg production in layer hen breeding. The SNP molecular markers affecting the age of egg production include AFE_chr16_1 and AFE_chr16_2. The dominant genotype populations have an earlier age of egg production. Both AFE_chr16_1 and AFE_chr16_2 can help to advance the age of egg production in layer hens genetically. Applying them to chicken genetic breeding is beneficial to improving the age of egg production in layer hens. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 Manhattan plot of GWAS analysis of the age at which the resource population begins production, Example 2 of this invention;

[0042] Figure 2 This is a GWAS analysis QQ plot of the age at which the resource population begins production in Embodiment 2 of the present invention;

[0043] Figure 3 Box plots of age at first labor for individuals with different genotypes in Example 3 of this invention;

[0044] Figure 4 Box plots showing the age at first labor of individuals with different genotypes in Example 4 of this invention. Detailed Implementation

[0045] The present invention will be described in detail below with reference to specific embodiments and examples, thereby making the advantages and various effects of the present invention more clearly apparent. Those skilled in the art should understand that these specific embodiments and examples are for illustrative purposes only and are not intended to limit the present invention.

[0046] Throughout this specification, unless otherwise specified, the terminology 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 commonly understood by one of ordinary skill in the art to which this invention pertains. In the event of any conflict, this specification shall prevail.

[0047] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0048] The following will provide a detailed description of the application of SNP molecular markers affecting the age of first egg production in laying hen breeding, in conjunction with embodiments and experimental data.

[0049] Example 1

[0050] Resource Group Building

[0051] To analyze the genetic structure of egg production traits, a laying hen resource population was constructed based on the F2 design. The local Dongxiang Green-shelled Chicken and the selectively bred White Leghorn Chicken were used as parents, and the F1 generation was obtained through reciprocal crosses. The F2 generation was then bred using the F1 generation as parents. Pedigree information was recorded. The experimental chickens were individually tagged with wing tags and housed in single cages in a fully enclosed chicken house. Artificial lighting was provided for 16 hours during the laying period, and cooling was achieved using fans and evaporative cooling pads. Routine immunizations were administered according to the immunization program established by the Jiangsu Provincial Poultry Research Institute. Feed was supplied by COFCO, and the laying hen feed composition included 16.5% crude protein and 11511 kJ / kg metabolizable energy. During the laying period, chickens had free access to feed, with water provided by nipple drinkers, feed supplied by a traveling feeder, and manure removed by a manure conveyor belt. The age at first laying of each experimental chicken was recorded.

[0052] The data on age at first egg production was initially screened, removing obvious errors and duplicates, outliers, and compiled into an Excel spreadsheet. The remaining 1512 records in the F2 generation data set of the resource population were analyzed using one-way ANOVA to determine the influence of generation and breed on the experimental data, identifying year and coop effects as factors to be included in the fixed effects. WOMBAT software was used to construct a genetic relationship matrix from the pedigree data, calculating heritability and breeding values. These breeding values ​​were used as pseudo-phenotypic data for the next step of GWAS analysis to analyze the genetic structure of age at first egg production.

[0053] Example 2

[0054] GWAS analysis of age at onset of labor

[0055] The experimental chickens were adult hens from the F2 generation of the laying hen resource population constructed in Example 1. Approximately 0.5 ml of blood was collected from the wing vein of each chicken and placed in a BD anticoagulant tube (Suzhou BD Medical Instruments Co., Ltd.) for storage at -70℃. Genomic DNA was extracted and analyzed by 0.8% agarose gel electrophoresis and ultraviolet spectrophotometry. After passing the analysis, the DNA sample was diluted to 50±5 ng / μl for gene chip typing.

[0056] Using Angfei's gene chip Genotyping was performed using a 600K Chicken Genotyping Array. Data quality control was conducted according to the array's instruction manual, including: pre-genotyping quality control using APT software; PLINK quality control to remove SNPs with a detection rate below 0.97 and those deviating from Hardy-Weinberg equilibrium; SNP screening using metrics.R, SNP_filter.R, and SNP, CR, and FLD information analysis; and genotyping using BEAGLE. After quality control, 435,867 autosomal SNPs remained for subsequent analysis.

[0057] Prior to genome-wide association analysis (GWAS), multidimensional principal component analysis (PCA) was performed to eliminate false positives and assess population structure. The first five principal components were added as covariate parameters to the genetic model, and the chicken coop effect was incorporated into the model as a fixed effect. The independence test estimates for each SNP were calculated using the R script "simpleM" method, yielding 59,308 independent markers. Using multiple correction, the genomic significance threshold was determined to be 8.43 × 10⁻⁶. -7 The suggested threshold for genome sequencing is 1.69 × 10⁻⁶. -5 The age at egg onset was analyzed using a mixed linear model, and the p-values ​​for the significance tests of each SNP marker were obtained. The matrix expression of the linear model is as follows:

[0058] y = Wα + xβ + Gu + ε

[0059] Where y represents the sample phenotypic value vector; W represents the covariance matrix; α is the intercept vector; x is the genotype vector of the label; β is the effect value of the label; G is the genetic relationship matrix constructed based on the microarray; u is the random effect vector (here, the breeding value); and ε is the residual.

[0060] GWAS screening yielded AFE_chr16_1 (Table 1) associated with age at first laying. Genome-wide association analysis was performed on 1512 chickens at age at first laying, and the results are as follows: Figure 1 , Figure 2 As shown. By Figure 1 The Manhattan plot shows a significant genomic marker on chicken chromosome 16, with two SNPs around it exceeding the recommended genomic level, providing evidence for AFE_chr16_1. The QQ plot further validates the reliability of the GWAS results. Figure 2(QQ plot) As can be seen, the vast majority of SNPs that did not deviate from the slant line are affected by genetic drift, while SNPs located at the tail of the QQ plot are affected by artificial selection. The calculated expansion coefficient is 1.016, indicating that there is no obvious population stratification for the age at first fertility trait in the resource population. Genetic parameters were analyzed using the pedigree genetic relationship matrix, and the heritability of age at first fertility was found to be 0.392±0.046, of which the AFE_chr16_1 genetic marker explained 1.14% of the phenotypic variance, and the AFE_chr16_2 genetic marker explained 0.89% of the phenotypic variance.

[0061] Table 1 Genetic markers associated with age at labor

[0062]

[0063] Wherein: the physical location of the marker chromosome is referenced to the whole chicken genome (bGalGal1.mat.broiler.GRCg7b).

[0064] Example 3

[0065] Detection and validation of the genetic marker AFE_chr16_1.

[0066] 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:

[0067] 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 2. PCR primers were synthesized by Sangon Biotech (Shanghai) Co., Ltd.

[0068] Table 2. Amplification primers used to detect the genetic marker AFE_chr16_1 at chicken laying age.

[0069]

[0070] 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.

[0071] 3) PCR amplification process:

[0072] 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.

[0073] ②Reaction procedure: First, denature at 94℃ for 30s, anneal at 55.4℃ for 30s, extend at 72℃ for 30s, for a total of 5 cycles; then, denature at 94℃ for 30s, anneal at 55.4℃ for 30s, extend at 72℃ for 30s, for a total of 30 cycles; extend at 72℃ for 5min, and store at 4℃.

[0074] 4) The amplified products are sent to a sequencing company for sequence polymorphism detection.

[0075] The amplified fragment sequence is shown below:

[0076] >AFE_chr16_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 age at onset, and then significance tests were performed. The results are as follows: Figure 3 As shown, the age at first laying of individuals with the GG genotype was 160.18 ± 10.64 days, that of individuals with the GC genotype was 154.67 ± 10.52 days, and that of individuals with the CC genotype was 152.71 ± 10.59 days. One-way ANOVA showed significant differences in the age at first laying among the three genotypes (P < 0.01). Genotyping techniques, increasing the frequency of the C allele, can shorten the age at first laying in laying hens; increasing the frequency of the CC genotype can further improve the uniformity of the age at first laying in laying hens.

[0080] Example 4

[0081] Detection and validation of the genetic marker AFE_chr16_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: Download DNA template sequence information from the NCBI website and design PCR primers using Primer Premier 6.0 software.

[0084] Amplification primers are shown in Table 3. PCR primers were synthesized by Sangon Biotech (Shanghai) Co., Ltd.

[0085] Table 3. Amplification primers used to detect the genetic marker AFE_chr16_2 at the age of chicken laying.

[0086]

[0087]

[0088] 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.

[0089] 3) PCR amplification process:

[0090] 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.

[0091] ②Reaction procedure: First, denature at 94℃ for 30s, anneal at 54.2℃ for 30s, extend at 72℃ for 30s, for a total of 5 cycles; then, denature at 94℃ for 30s, anneal at 54.2℃ for 30s, extend at 72℃ for 30s, for a total of 30 cycles; extend at 72℃ for 5min, and store at 4℃.

[0092] 4) The amplified products are sent to a sequencing company for sequence polymorphism detection.

[0093] The amplified fragment sequence is shown below:

[0094] >AFE_chr16_2

[0095]

[0096] 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.

[0097] 5) Association Analysis: All tested individuals had genotypes and age at first egg production, and significance tests were performed. Results showed that the age at first egg production for individuals with the CC genotype was 158.50 ± 10.97 days, for those with the TC genotype it was 154.64 ± 10.71 days, and for those with the TT genotype it was 152.93 ± 10.55 days. One-way ANOVA showed significant differences in age at first egg production among the three genotypes. Genotyping techniques, increasing the frequency of the T allele, can shorten the age at first egg production in laying hens, and increasing the frequency of the TT genotype can improve the evenness of age at first egg production.

[0098] Finally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0099] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0100] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. The application of SNP molecular markers affecting the age of first egg production in laying hen breeding, characterized in that, The SNP molecular markers that affect the age of first laying in chickens include AFE_chr16_1 and / or AFE_chr16_2; The Ensembl number of AFE_chr16_1 is rs316781747, which corresponds to position 2078538 on the positive strand of chromosome 16 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI. It belongs to the first intron of the gene TRIM7.2, where the base is G or C. The Ensembl number of AFE_chr16_2 is rs15788024, which corresponds to position 2121574 on the positive strand of chromosome 16 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI. It belongs to the 4th intron of the gene TRIM39.2, where the base is T or C. The aforementioned egg-laying hen breeding refers to the breeding of egg-laying hens with respect to the age at which they begin laying eggs; The age at onset of labor for individuals with the CC genotype of AFE_chr16_1 was earlier than that for individuals with the GC and GG genotypes. The TT genotype individuals of the AFE_chr16_2 strain had an earlier age of onset than the TC and CC genotype individuals.

2. A method for early selection of chickens based on their age at first laying, characterized in that, The early selection method includes early selection of chickens based on the genotype of the SNP molecular markers AFE_chr16_1 or AFE_chr16_2 for the age at first laying trait; The Ensembl number of AFE_chr16_1 is rs316781747, which corresponds to position 2078538 on the positive strand of chromosome 16 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI. It belongs to the first intron of the gene TRIM7.2, where the base is G or C. The Ensembl number of AFE_chr16_2 is rs15788024, which corresponds to position 2121574 on the positive strand of chromosome 16 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI. It belongs to the 4th intron of the gene TRIM39.2, where the base is T or C. Among them, the age at onset of labor of individuals with the CC genotype of AFE_chr16_1 is earlier than that of individuals with the GC and GG genotypes; The TT genotype individuals of the AFE_chr16_2 strain had an earlier age of onset than the TC and CC genotype individuals.

3. The method for early selection of chickens based on their age at first laying, as described in claim 2, is characterized in that... The early selection method specifically includes: Detect the genotype of the SNP molecular markers AFE_chr16_1 or AFE_chr16_2 in the chickens to be tested; Early selection of the age at first laying of chickens is performed based on the genotype of AFE_chr16_1 or AFE_chr16_2.

4. The method for early selection of chickens based on their age at first laying, as described in claim 3, is characterized in that... The detection of the genotype of the chicken SNP molecular markers AFE_chr16_1 or AFE_chr16_2 specifically includes: The genotypes of the SNP molecular markers AFE_chr16_1 or AFE_chr16_2 in the target chicken were detected. The method for detecting the AFE_chr16_1 genotype is as follows: Using Pr_afe_16_1f and Pr_afe_16_1r as primers, PCR amplification was performed on the genomic DNA of the chickens to be tested. The PCR amplification products were sequenced to obtain the genotype at position 2078538 on the positive strand of chromosome 16 of the chicken to be tested. The method for detecting the AFE_chr16_2 genotype is as follows: Using Pr_afe_16_2f and Pr_afe_16_2r as primers, PCR amplification was performed on the genomic DNA of the chickens to be tested; The PCR amplification products were sequenced to obtain the genotype at position 2121574 on the positive strand of chromosome 16 of the chicken to be tested. The nucleotide sequence of Pr_afe_16_1f is shown in SEQ ID NO.1, the nucleotide sequence of Pr_afe_16_1r is shown in SEQ ID NO.2, the nucleotide sequence of Pr_afe_16_2f is shown in SEQ ID NO.3, and the nucleotide sequence of Pr_afe_16_2r is shown in SEQ ID NO.

4.

5. A method for early selection of chickens based on age at first laying, as described in claim 3 or 4, characterized in that, The breeds of chickens to be tested include Dongxiang Green-shelled Egg Chicken and / or White Leghorn Chicken.

6. The application of a detection reagent for SNP molecular markers affecting the age of egg production in laying hen genetic breeding, characterized in that, The SNP molecular markers that affect the age of first laying in chickens include AFE_chr16_1 or AFE_chr16_2; The Ensembl number of AFE_chr16_1 is rs316781747, which corresponds to position 2078538 on the positive strand of chromosome 16 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI. It belongs to the first intron of the gene TRIM7.2, where the base is G or C. The Ensembl number of AFE_chr16_2 is rs15788024, which corresponds to position 2121574 on the positive strand of chromosome 16 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI. It belongs to the 4th intron of the gene TRIM39.2, where the base is T or C. The aforementioned layer hen genetic breeding refers to the genetic breeding of layer hens regarding the trait of age at first egg production; The age at onset of labor for individuals with the CC genotype of AFE_chr16_1 was earlier than that for individuals with the GC and GG genotypes. The TT genotype individuals of the AFE_chr16_2 strain had an earlier age of onset than the TC and CC genotype individuals.

7. The application according to claim 6, characterized in that, The detection reagent for SNP molecular markers affecting the age of first laying in chickens includes primers for detecting AFE_chr16_1 or AFE_chr16_2. The primers for detecting AFE_chr16_1 include Pr_afe_16_1f and Pr_afe_16_1r, and the primers for detecting AFE_chr16_2 include Pr_afe_16_2f and Pr_afe_16_2r. The nucleotide sequence of Pr_afe_16_1f is shown in SEQ ID NO.1, the nucleotide sequence of Pr_afe_16_1r is shown in SEQ ID NO.2, the nucleotide sequence of Pr_afe_16_2f is shown in SEQ ID NO.3, and the nucleotide sequence of Pr_afe_16_2r is shown in SEQ ID NO.

4.

8. The application of a kit for detecting SNP molecular markers affecting the age of first laying in chickens in chicken genetic breeding, characterized in that, The kit contains primers for detecting AFE_chr16_1 or AFE_chr16_2, wherein the primers for detecting AFE_chr16_1 include Pr_afe_16_1f and Pr_afe_16_1r, and the primers for detecting AFE_chr16_2 include Pr_afe_16_2f and Pr_afe_16_2r; The nucleotide sequence of Pr_afe_16_1f is shown in SEQ ID NO.1, the nucleotide sequence of Pr_afe_16_1r is shown in SEQ ID NO.2; the nucleotide sequence of Pr_afe_16_2f is shown in SEQ ID NO.3, and the nucleotide sequence of Pr_afe_16_2r is shown in SEQ ID NO.

4. The chicken genetic breeding mentioned above refers to the genetic breeding of chickens regarding the trait of age at first egg production; The age at onset of labor for individuals with the CC genotype of AFE_chr16_1 was earlier than that for individuals with the GC and GG genotypes. The TT genotype individuals of the AFE_chr16_2 strain had an earlier age of onset than the TC and CC genotype individuals.

9. The application of SNP molecular markers affecting the age of laying in chickens in predicting the age of laying, characterized in that, The SNP molecular markers that affect the age of first laying in chickens include AFE_chr16_1 or AFE_chr16_2; The Ensembl number of AFE_chr16_1 is rs316781747, which corresponds to position 2078538 on the positive strand of chromosome 16 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI. It belongs to the first intron of the gene TRIM7.2, where the base is G or C. The Ensembl number of AFE_chr16_2 is rs15788024, which corresponds to position 2121574 on the positive strand of chromosome 16 of the chicken reference genome bGalGal 1.mat.broiler.GRCg7b sequence published in NCBI. It belongs to the 4th intron of the gene TRIM39.2, where the base is T or C. Among them, the age at onset of labor of individuals with the CC genotype of AFE_chr16_1 is earlier than that of individuals with the GC and GG genotypes; The TT genotype individuals of the AFE_chr16_2 strain had an earlier age of onset than the TC and CC genotype individuals.

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