Use of a SNP molecular marker related to chicken intestinal tract length in chicken genetic breeding

Abstract

The application provides application of a SNP molecular marker related to chicken intestinal tract length in chicken genetic breeding, and belongs to the field of animal genetic breeding and biotechnology.The SNP molecular marker related to chicken intestinal tract length comprises CC_tag1 or CC_tag2, the Ensembl number of the CC_tag1 is rs316174677, corresponds to sequence information of a chicken reference genome bGalGal1.mat.broCCer.GRCg7b version 1 of a No.1 chromosome physical position 167839822, is located in the 18th intron of a gene ZC3H13, and bases at the position are G or T.The SNP molecular marker related to chicken intestinal tract length is helpful to genetically improve the intestinal tract length, is applied to chicken genetic breeding, and is favorable to improving the intestinal tract length and obtaining a better egg-laying chicken breed in nutrition absorption.

Description

Technical Field

[0001] This invention belongs to the fields of animal genetics and breeding and biotechnology, and specifically relates to the application of a SNP molecular marker related to chicken intestinal length in chicken genetics and breeding. Background Technology

[0002] The intestine is the primary organ for nutrient digestion and absorption in laying hens. Previous studies have found that a longer intestine, with more abundant intestinal villi, results in longer food retention time and a larger contact area with the villi, leading to higher digestive and absorptive efficiency. This significantly improves feed utilization and, consequently, egg production performance. Therefore, intestinal length can be used as an important indicator for selecting laying hens and predicting egg production performance.

[0003] However, intestinal length is primarily determined post-slaughter, making conventional breeding methods very difficult. Compared to traditional breeding, molecular selection using trait-related markers can effectively accelerate the breeding process. Therefore, identifying molecular marker sites that influence intestinal length and improving breeding populations is crucial for enhancing the production performance and economic benefits of laying hens. 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, the genetic structure of intestinal length in laying hens is rarely analyzed using GWAS. Intestinal length is regulated by multiple genes with minor effects, and conventional breeding methods struggle to achieve significant genetic progress. Only by clarifying the genetic structure of intestinal length and improving the accuracy of breeding through genomic selection can we genetically influence intestinal length.

[0004] The Dongxiang Green-Shelled Chicken, originating from the area near Dongxiang County, Jiangxi Province, is named for its green-shelled eggs and is a well-known local egg-laying chicken breed in my country. It has a long history of being raised in rural areas. After selective breeding, the Dongxiang Green-Shelled Chicken is used to construct the Suqin Green-Shelled Chicken and Shendan No. 6 Green-Shelled Chicken breeding lines, occupying an important position in the egg-laying chicken market. Systematic research on the genetic structure of intestinal length in the Dongxiang Green-Shelled Chicken is of great significance for the development and utilization of this breed and other egg-laying chicken breeds. However, intestinal length can only be measured after slaughter, which is costly and does not allow for direct selection of individuals. Therefore, it is urgent to find suitable molecular markers to achieve early selection through marker-assisted breeding or genomic selection, in order to quickly obtain genetic progress on intestinal length in egg-laying chickens. Summary of the Invention

[0005] To obtain laying hen breeds with superior intestinal length traits, this invention provides the application of SNP molecular markers related to chicken intestinal length in chicken genetic breeding. These SNP molecular markers help to genetically improve intestinal length, and their application in chicken genetic breeding is beneficial for improving intestinal length and obtaining laying hen breeds with better nutrient absorption.

[0006] This invention is achieved through the following technical solution: This invention provides the application of SNP molecular markers related to chicken intestinal length in chicken genetic breeding. The SNP molecular markers related to chicken intestinal length include CC_tag1 or CC_tag2. The Ensembl number of CC_tag1 is rs316174677, which corresponds to the 167839822nd position of the chicken reference genome bGalGal1.mat.broCCer.GRCg7b version sequence information published by NCBI, located in the 18th intron of gene ZC3H13, where the base is G or T. The Ensembl number of CC_tag2 is rs14915060, which corresponds to position 167845161 on the positive strand of chromosome 1 of the chicken reference genome bGalGal1.mat.broCCer.GRCg7b sequence published in NCBI, where the base is A or G.

[0007] Based on the same inventive concept, the present invention provides an early selection method for the chicken intestinal length trait, the early selection method comprising early selection of the chicken intestinal length trait based on the genotypes of SNP molecular markers CC_tag1 and / or CC_tag2; The Ensembl number of CC_tag1 is rs316174677, which corresponds to the 167839822nd position of the physical location of chromosome 1 in the chicken reference genome bGalGal1.mat.broCCer.GRCg7b version sequence information published by NCBI. It is located in the 18th intron of gene ZC3H13, and the base here is G or T. The Ensembl number of CC_tag2 is rs14915060, which corresponds to position 167845161 on the positive strand of chromosome 1 of the chicken reference genome bGalGal1.mat.broCCer.GRCg7b sequence published in NCBI, where the base is A or G.

[0008] Optionally, the early selection method specifically includes: Detect the genotypes of SNP molecular markers CC_tag1 and / or CC_tag2 in the genome of the chicken to be tested; Early selection of the intestinal length trait to be tested based on the genotypes of CC_tag1 and / or CC_tag2; Among them, the intestinal length of GG individuals of CC_tag1 is greater than that of GT individuals (P<0.01), and the intestinal length of GT genotype individuals is greater than that of TT genotype individuals (P<0.01). The intestinal length of AA individuals in CC_tag2 is greater than that of AG individuals, and the intestinal length of AG genotype individuals is greater than that of GG genotype individuals.

[0009] Optionally, the detection of the genotypes of SNP molecular markers CC_tag1 and / or CC_tag2 in the genome of the chicken to be tested specifically includes: Genotyping of the SNP molecular marker CC_tag1 in the genome of the chicken to be tested: Using Pr_CC1f and Pr_CC1r as primers, PCR amplification was performed on the genomic DNA of the chicken to be tested. The PCR amplification products were sequenced to obtain the genotype at position 167839822 on the positive strand of chromosome 1 of the chicken to be tested; The nucleotide sequence of Pr_CC1f is shown in SEQ ID NO.1, and the nucleotide sequence of Pr_CC1r is shown in SEQ ID NO.2; Alternatively, detect the genotype of the SNP molecular marker CC_tag2 in the genome of the chicken to be tested: Using Pr_CC2f and Pr_CC2r as primers, PCR amplification was performed on the genomic DNA of the chicken to be tested; The PCR amplification products were sequenced to obtain the genotype at position 167845161 on the positive strand of chromosome 1 of the chicken to be tested. The nucleotide sequence of Pr_CC2f is shown in SEQ ID NO.3, and the nucleotide sequence of Pr_CC2r is shown in SEQ ID NO.4.

[0010] Optionally, the breed of chicken to be tested includes Dongxiang Green-shelled Chicken and / or White Leghorn Chicken.

[0011] Based on the same inventive concept, the present invention provides detection primers for SNP molecular markers related to chicken intestinal length, the detection primers including primers for detecting CC_tag1 and / or primers for detecting CC_tag2, the primers for detecting CC_tag1 including Pr_CC1f and Pr_CC1r, the nucleotide sequence of Pr_CC1f is shown in SEQ ID NO.1, and the nucleotide sequence of Pr_CC1r is shown in SEQ ID NO.2; The primers for detecting CC_tag2 include Pr_CC2f and Pr_CC2r, the nucleotide sequence of which is shown in SEQ ID NO.3 and the nucleotide sequence of which is shown in SEQ ID NO.4.

[0012] Based on the same inventive concept, this invention provides the application of detection primers for SNP molecular markers related to chicken intestinal length in chicken genetic breeding.

[0013] Based on the same inventive concept, the present invention provides a detection kit for SNP molecular markers related to chicken intestinal length, the kit comprising the detection primers for the aforementioned SNP molecular markers related to chicken intestinal length.

[0014] Based on the same inventive concept, this invention provides a detection kit for SNP molecular markers related to chicken intestinal length and its application in chicken genetic breeding.

[0015] Based on the same inventive concept, this invention provides the application of SNP molecular markers related to chicken intestinal length in predicting chicken intestinal length. The SNP molecular markers related to chicken intestinal length include CC_tag1 or CC_tag2. The Ensembl number of CC_tag1 is rs316174677, which corresponds to the 167839822nd position of the chicken reference genome bGalGal1.mat.broCCer.GRCg7b version sequence information published by NCBI, located in the 18th intron of gene ZC3H13, where the base is G or T. The Ensembl number of CC_tag2 is rs14915060, which corresponds to position 167845161 on the positive strand of chromosome 1 of the chicken reference genome bGalGal1.mat.broCCer.GRCg7b sequence published in NCBI, where the base is A or G.

[0016] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages: 1. The present invention relates to the application of SNP molecular markers related to chicken intestinal length in chicken genetic breeding. The molecular markers related to chicken intestinal length are CC_tag1 and / or CC_tag2. Chicken populations with dominant genotypes of CC_tag1 and CC_tag2 have longer intestinal lengths. These markers can be applied to chicken genetic breeding or early selection, which helps to genetically select laying hen breeds with better intestinal length, improve the intestinal length and nutrient absorption of laying hens, and accelerate the breeding process.

[0017] 2. This invention relates to the application of SNP molecular markers related to chicken intestinal length in chicken genetic breeding. Dongxiang green-shelled laying hens, due to a lack of intensive selective breeding, exhibit poor production performance. To meet the market demand for green-shelled eggs and to explore local chicken breed genetic resources, this invention provides SNP molecular markers CC_tag1 and CC_tag2 related to chicken intestinal length. These markers help to genetically improve the intestinal length of laying hens. Applying them to chicken genetic breeding can yield laying hen breeds with better nutrient absorption, which is of great significance for the development and utilization of laying hen breeds such as Dongxiang green-shelled laying hens and White Leghorn chickens. Attached Figure Description

[0018] 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.

[0019] Figure 1 Manhattan plot of GWAS analysis of gut length in resource population in Embodiment 2 of the present invention; Figure 2 This is a QQ plot of GWAS analysis of gut length in the resource population in Embodiment 2 of the present invention; Figure 3 Box plots of intestinal length for individuals with different genotypes in Examples 3 and 4 of this invention. Detailed Implementation

[0020] 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.

[0021] 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.

[0022] 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.

[0023] The following will provide a detailed description of the application of a SNP molecular marker related to chicken intestinal length in chicken genetic breeding, in conjunction with embodiments and experimental data.

[0024] Example 1 Resource group building To analyze the genetic structure of laying hens' 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 Institute of Poultry Science. 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. Intestinal length was measured according to the industry standards of the Ministry of Agriculture and Rural Affairs of the People's Republic of China.

[0025] After initial screening of the intestinal length data to remove obviously erroneous and duplicate data, outliers were removed, and the data was compiled into an Excel spreadsheet. Following data cleaning, the F2 generation intestinal length dataset of the resource population contained 1413 records, which were used for the next step of GWAS analysis to determine their genetic structure.

[0026] Example 2 GWAS analysis of intestinal length 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 the experimental chickens and placed in BD anticoagulant tubes (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 genotyping using a gene chip.

[0027] Using Affymetrix gene chip from Affymetrix Axiom 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.

[0028] 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 A mixed linear model was used to analyze the intestinal length of laying hens, and the p-values ​​for the significance test of each SNP were obtained. The matrix expression of the linear model is as follows:

[0029] Where y represents the sample phenotypic value vector; W represents the covariance matrix; α is the intercept vector; x is the marker genotype vector; β is the marker effect value; 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.

[0030] GWAS screening yielded CC_tag1 and CC_tag2 (Table 1) associated with intestinal length. Genome-wide association analysis was performed on the intestinal length of 1413 chickens, and the results are as follows: Figure 1 , Figure 2 As shown. By Figure 1 The Manhattan plot shows that chicken chromosome 1 contains genomically significant markers, with 380 SNPs exceeding genomic significance and 211 SNPs exceeding the suggested genomic level in its vicinity, which can serve as evidence to support CC_tag1 and CC_tag2. The QQ plot further verifies the reliability of the GWAS results.

[0031] Table 1 Molecular markers associated with intestinal length ; Wherein: the physical location of the marker chromosome is referenced to the whole chicken genome (bGalGal1.mat.broiler.GRCg7b).

[0032] Example 3 Detection and validation of the molecular marker CC_tag1 The above-mentioned SNP molecular markers were used to perform candidate gene association analysis on the Dongxiang green-shelled egg-laying chicken-Leihun chicken resource population. The specific operation steps are as follows: 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.

[0033] Table 2. Amplification primers used for detecting the molecular marker CC_tag1 in chicken intestine length. ; 2) Genomic DNA extraction: Genomic DNA was extracted from 1391 blood samples using the phenol-formaldehyde method. After passing the tests by ultraviolet spectrophotometer and agarose electrophoresis, PCR amplification was performed.

[0034] 3) PCR amplification process: ① Reaction system: The 20μl system includes 50ng of DNA template for identification, 10ng each of forward and reverse primers, 10μL of 2×power Taq MasterMix, and the remaining volume is made up with ultrapure water.

[0035] ②Reaction procedure: First, denature at 94℃ for 2 min; then denature at 94℃ for 30 s, anneal at 55.1℃ for 30 s, extend at 72℃ for 30 s, for a total of 30 cycles; extend at 72℃ for 5 min, and store at 4℃.

[0036] 4) The amplified products are sent to a sequencing company for sequence polymorphism detection.

[0037] The amplified fragment sequence is shown below: >CC_tag1 ACATGTGGAGTTTGCCTGAGACTCCTAGCAGAAGAAACTGCATATGCTCAAATGCACATTTCACATGTGGTAACTTTGATGAGCAGGAGACTGCACACATCAAAGGGAAAGTAATGGAGACACTTCAACCTCTCTTTCCT CTGGAGTAAACTCCCCTGCATCTGAGTACACTCAAAACAACACAGAGGAAGTGCTAGAGAGACA[G / T]CTACTATCACCACTCTGCTGAACTTTATGTCTAGAGATGCATGCAAGGACTGCTGAGGTGGTTTCAGGTAAT ATTTTAAACAACCAGGTGAATTCTGCACTGCAGTTCCTGTTACAAGGAATGCTTGATAAGAGCTGTTGAAGTATAAAGCAAAATTAAAGCTTACAGAGAAAACAGCATTGTTCCTACTTTTTCTGTATCAGACAGTTTGCA AGCTCAGGAAGATAAATAGTGTGTTATATCACTTATGGAAATTCCTAGGCATAAGAGCTAAGATTATTTTTTAAACTAGAGAAAAGCAAATACTGCAAAAAAAAACAAAAGAACTGTAAGCCTCACAGAATGCTTACATGA In the sequence, the marked [ ] are mutation sites, where allele variation is represented, and the bolded parts at both ends of the sequence are primer sequences.

[0038] 5) Association analysis: All participants had their genotype and gut length, and then a significance test was performed. The analysis results are as follows: Figure 3 As shown in the left figure, the intestinal length of individuals with the GG genotype was 145.85±13.09 cm, that of individuals with the GT genotype was 140.52±11.92 cm, and that of individuals with the TT genotype was 13.11±12.88 cm. One-way ANOVA showed that the differences in intestinal length among the three genotypes were extremely significant, and pairwise comparisons further confirmed the existence of extremely significant differences in intestinal length. Increasing the frequency of the G allele through genotyping technology can significantly improve the intestinal length of laying hens.

[0039] Example 4 Detection and validation of the molecular marker CC_tag2 The above-mentioned SNP molecular markers were used to perform candidate gene association analysis on the Dongxiang green-shelled egg-laying chicken-Leihun chicken resource population. The specific operation steps are as follows: 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.

[0040] Table 3. Amplification primers used for detecting the molecular marker CC_tag2 in chicken intestine length. ; 2) Genomic DNA extraction: Genomic DNA was extracted from 1391 blood samples using the phenol-formaldehyde method. After passing the tests by ultraviolet spectrophotometer and agarose electrophoresis, PCR amplification was performed.

[0041] 3) PCR amplification process: ① Reaction system: The 20μl system includes 50ng of DNA template for identification, 10ng each of forward and reverse primers, 10μL of 2×power Taq MasterMix, and the remaining volume is made up with ultrapure water.

[0042] ②Reaction procedure: First, denature at 94℃ for 2 min; then denature at 94℃ for 30 s, anneal at 54.6℃ for 30 s, extend at 72℃ for 30 s, for a total of 30 cycles; extend at 72℃ for 5 min, and store at 4℃.

[0043] 4) The amplified products are sent to a sequencing company for sequence polymorphism detection.

[0044] The amplified fragment sequence is shown below: >CC_tag2 ATCTGGAGTGGACCTGACGATCTGATTCAGGAGAACTTCTTCTTGAACTGTGGCTTCTTGAATTCTGACGATCTGAATAAAATAGACAGCAGCTCAGGAAACCATTCTGTTACACCAAACTATTTTAAGGAGTCTGGTATGAAAACTG ATTTCTGAAAAGTATCACCAGAAATTAATAAAAAAAAAATGCAGTCATTTCTTTATAGGAACTACAGAAGTAAATAAATCAATTGTGATTCCTTAGATTTGCAATAAAGATGACATCCATATGCAAT AAAAGTATCCCTATGAAGAATCATGACAGATTTACCTCAGCAAAAACAGCTCCTGAGATCAAAATGGATCCCTTTCCCAGAATGAAGGGACATTTTGCATA[A / G]ATCTCGGAATTTCCACATGAAA ATGAATGTTGATAATTCATTAAAAACATTTTTTTTTTCAATAAAACTAGTTCACTGTTCTGTTAGCAGAAGGATTTTCTTCTTTCAGTTTCATTTGTCCTAGAAATTACTTTATCCTCCAGACAGCACAA ACTGCCAAATCTGACTGAACG In the sequence, the marked [ ] are mutation sites, where allele variation is represented, and the bolded parts at both ends of the sequence are primer sequences.

[0045] 5) Association analysis: All participants had their genotype and gut length, and then a significance test was performed. The analysis results are as follows: Figure 3 As shown in the right figure, the intestinal length of individuals with the AA genotype was 145.76±13.11 cm, that of individuals with the AG genotype was 140.18±12.15 cm, and that of individuals with the GG genotype was 135.34±12.70 cm. One-way ANOVA showed that the differences in intestinal length among the three genotypes were extremely significant, and pairwise comparisons further confirmed the existence of extremely significant differences in intestinal length. Increasing the frequency of the A allele through genotyping technology can significantly improve the intestinal length of laying hens.

[0046] 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.

[0047] 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.

[0048] 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 a SNP molecular marker related to chicken intestinal length in chicken genetic breeding, characterized in that, The SNP molecular markers related to chicken intestinal length include CC_tag1 or CC_tag2. CC_tag1 has an Ensembl number of rs316174677, which corresponds to the 167839822nd position on chromosome 1 of the chicken reference genome bGalGal1.mat.broCCer.GRCg7b version sequence information published by NCBI, located in the 18th intron of gene ZC3H13, where the base is G or T. The Ensembl number of CC_tag2 is rs14915060, which corresponds to position 167845161 on the positive strand of chromosome 1 of the chicken reference genome bGalGal1.mat.broCCer.GRCg7b sequence published in NCBI, where the base is A or G.

2. A method for early selection of chicken intestinal length traits, characterized in that, The early selection method includes early selection of chicken intestinal length traits based on the genotypes of SNP molecular markers CC_tag1 and / or CC_tag2; The Ensembl number of CC_tag1 is rs316174677, which corresponds to the 167839822nd position of the physical location of chromosome 1 in the chicken reference genome bGalGal1.mat.broCCer.GRCg7b version sequence information published by NCBI. It is located in the 18th intron of gene ZC3H13, and the base here is G or T. The Ensembl number of CC_tag2 is rs14915060, which corresponds to position 167845161 on the positive strand of chromosome 1 of the chicken reference genome bGalGal1.mat.broCCer.GRCg7b sequence published in NCBI, where the base is A or G.

3. The method for early selection of chicken intestinal length traits according to claim 2, characterized in that, The early selection method specifically includes: Detect the genotypes of SNP molecular markers CC_tag1 and / or CC_tag2 in the genome of the chicken to be tested; Early selection of the intestinal length trait to be tested based on the genotypes of CC_tag1 and / or CC_tag2; Among them, the intestinal length of the GG individuals of CC_tag1 is greater than that of the GT individuals, and the intestinal length of the GT genotype individuals is greater than that of the TT genotype individuals. The intestinal length of AA individuals in CC_tag2 is greater than that of AG individuals, and the intestinal length of AG genotype individuals is greater than that of GG genotype individuals.

4. The method for early selection of chicken intestinal length traits according to claim 3, characterized in that, The detection of the genotypes of SNP molecular markers CC_tag1 and / or CC_tag2 in the genome of the chicken to be tested specifically includes: Genotyping of the SNP molecular marker CC_tag1 in the genome of the chicken to be tested: Using Pr_CC1f and Pr_CC1r as primers, PCR amplification was performed on the genomic DNA of the chicken to be tested. The PCR amplification products were sequenced to obtain the genotype at position 167839822 on the positive strand of chromosome 1 of the chicken to be tested; The nucleotide sequence of Pr_CC1f is shown in SEQ ID NO.1, and the nucleotide sequence of Pr_CC1r is shown in SEQ ID NO.2; Alternatively, detect the genotype of the SNP molecular marker CC_tag2 in the genome of the chicken to be tested: Using Pr_CC2f and Pr_CC2r as primers, PCR amplification was performed on the genomic DNA of the chicken to be tested; The PCR amplification products were sequenced to obtain the genotype at position 167845161 on the positive strand of chromosome 1 of the chicken to be tested. The nucleotide sequence of Pr_CC2f is shown in SEQ ID NO.3, and the nucleotide sequence of Pr_CC2r is shown in SEQ ID NO.

4.

5. A method for early selection of chicken intestinal length traits according to 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. Primers for detecting SNP molecular markers related to chicken intestinal length, characterized in that, The detection primers include primers for detecting CC_tag1 and / or primers for detecting CC_tag2. The primers for detecting CC_tag1 include Pr_CC1f and Pr_CC1r, the nucleotide sequence of Pr_CC1f is shown in SEQ ID NO.1, and the nucleotide sequence of Pr_CC1r is shown in SEQ ID NO.

2. The primers for detecting CC_tag2 include Pr_CC2f and Pr_CC2r, the nucleotide sequence of which is shown in SEQ ID NO.3 and the nucleotide sequence of which is shown in SEQ ID NO.

4.

7. The application of the primers as described in claim 6 in chicken genetic breeding.

8. A detection kit for SNP molecular markers related to chicken intestinal length, characterized in that, The kit contains the primers as described in claim 6.

9. The application of the kit as described in claim 8 in chicken genetic breeding.

10. The application of SNP molecular markers associated with chicken intestinal length in predicting chicken intestinal length, characterized in that, The SNP molecular markers related to chicken intestinal length include CC_tag1 or CC_tag2. CC_tag1 has an Ensembl number of rs316174677, which corresponds to the 167839822nd position on chromosome 1 of the chicken reference genome bGalGal1.mat.broCCer.GRCg7b version sequence information published by NCBI, located in the 18th intron of gene ZC3H13, where the base is G or T. The Ensembl number of CC_tag2 is rs14915060, which corresponds to position 167845161 on the positive strand of chromosome 1 of the chicken reference genome bGalGal1.mat.broCCer.GRCg7b sequence published in NCBI, where the base is A or G.

Images